  Linux PCMCIA Programmer's Guide
  David Hinds, dahinds@users.sourceforge.net.
  v2.31, 04 May 2002

  This document describes how to write kernel device drivers for the
  Linux PCMCIA Card Services interface.  It also describes how to write
  user-mode utilities for communicating with Card Services.  The latest
  version of this document can always be found at <http://pcmcia-
  cs.sourceforge.net>.
  ______________________________________________________________________

  Table of Contents

  1. Introduction

     1.1 Copyright notice and disclaimer
     1.2 Acknowledgements

  2. Basic Concepts

     2.1 The socket interface
     2.2 The socket controller

  3. Card Services Subfunction Descriptions

     3.1 Client management functions
        3.1.1 RegisterClient
        3.1.2 DeregisterClient
        3.1.3 SetEventMask
        3.1.4 BindDevice
     3.2 Socket state control
        3.2.1 GetStatus
        3.2.2 ResetCard
        3.2.3 SuspendCard
        3.2.4 ResumeCard
        3.2.5 EjectCard
        3.2.6 InsertCard
     3.3 IO card configuration calls
        3.3.1 RequestIO
        3.3.2 ReleaseIO
        3.3.3 RequestIRQ
        3.3.4 ReleaseIRQ
        3.3.5 RequestConfiguration
        3.3.6 ModifyConfiguration
        3.3.7 ReleaseConfiguration
        3.3.8 GetConfigurationInfo
     3.4 Card Information Structure (CIS) calls
        3.4.1 GetFirstTuple, GetNextTuple
        3.4.2 GetTupleData
        3.4.3 ParseTuple
        3.4.4 ValidateCIS
        3.4.5 ReplaceCIS
     3.5 Memory window control
        3.5.1 RequestWindow
        3.5.2 ModifyWindow
        3.5.3 ReleaseWindow
        3.5.4 GetFirstWindow, GetNextWindow
        3.5.5 MapMemPage, GetMemPage
     3.6 Bulk Memory Services
        3.6.1 RegisterMTD
        3.6.2 GetFirstRegion, GetNextRegion
        3.6.3 OpenMemory
        3.6.4 CloseMemory
        3.6.5 ReadMemory, WriteMemory
        3.6.6 RegisterEraseQueue
        3.6.7 DeregisterEraseQueue
        3.6.8 CheckEraseQueue
     3.7 Miscellaneous calls
        3.7.1 GetCardServicesInfo
        3.7.2 AccessConfigurationRegister
        3.7.3 AdjustResourceInfo
        3.7.4 ReportError

  4. Card Information Structure Definitions

     4.1 CIS Tuple Definitions
        4.1.1 CISTPL_CHECKSUM
        4.1.2 CISTPL_LONGLINK_A, CISTPL_LONGLINK_C, CISTPL_LINKTARGET, CISTPL_NOLINK
        4.1.3 CISTPL_LONGLINK_MFC
        4.1.4 CISTPL_DEVICE, CISTPL_DEVICE_A
        4.1.5 CISTPL_VERS_1
        4.1.6 CISTPL_ALTSTR
        4.1.7 CISTPL_JEDEC_C, CISTPL_JEDEC_A
        4.1.8 CISTPL_CONFIG, CISTPL_CONFIG_CB
        4.1.9 CISTPL_BAR
        4.1.10 CISTPL_CFTABLE_ENTRY
        4.1.11 CISTPL_CFTABLE_ENTRY_CB
        4.1.12 CISTPL_MANFID
        4.1.13 CISTPL_FUNCID
        4.1.14 CISTPL_DEVICE_GEO
        4.1.15 CISTPL_VERS_2
        4.1.16 CISTPL_ORG
        4.1.17 CISTPL_FORMAT
     4.2 CIS configuration register definitions
        4.2.1 Configuration Option Register
        4.2.2 Card Configuration and Status Register
        4.2.3 Pin Replacement Register
        4.2.4 Socket and Copy Register
        4.2.5 Extended Status Register
        4.2.6 IO Base and Size Registers

  5. Card Services Event Handling

     5.1 Event handler operations
     5.2 Event descriptions
     5.3 Client driver event handling responsibilities

  6. Memory Technology Drivers

     6.1 MTD request handling
     6.2 MTD helper functions
        6.2.1 MTDRequestWindow, MTDReleaseWindow
        6.2.2 MTDModifyWindow
        6.2.3 MTDSetVpp
        6.2.4 MTDRDYMask

  7. Driver Services Interface

     7.1 Interface to other client drivers
        7.1.1 The dev_link_t structure
        7.1.2 register_pccard_driver
        7.1.3 unregister_pccard_driver
     7.2 The CardBus client interface
        7.2.1 register_driver
        7.2.2 unregister_driver
        7.2.3 The driver_operations entry points
     7.3 Interface to user mode utilities
        7.3.1 Card Services event notifications
        7.3.2 Ioctl descriptions

  8. Anatomy of a Card Services Client Driver

     8.1 Module initialization and cleanup
     8.2 The *_attach() and *_detach() functions
     8.3 The *_config() and *_release() functions
     8.4 The client event handler
     8.5 Locking and synchronization issues
     8.6 Using existing Linux drivers to access PC Card devices

  9. The Socket Driver Layer

     9.1 Card Services entry points for socket drivers
     9.2 Services provided by the socket driver
        9.2.1 SS_InquireSocket
        9.2.2 SS_RegisterCallback
        9.2.3 SS_GetStatus
        9.2.4 SS_GetSocket, SS_SetSocket
        9.2.5 SS_GetIOMap, SS_SetIOMap
        9.2.6 SS_GetMemMap, SS_SetMemMap
        9.2.7 SS_GetBridge, SS_SetBridge
        9.2.8 SS_ProcSetup
     9.3 Supporting unusual socket architectures

  10. Where to Go for More Information

  ______________________________________________________________________

  1.  Introduction

  The Linux kernel PCMCIA system has three main components.  At the
  lowest level are the socket drivers.  Next is the Card Services
  module.  Drivers for specific cards are layered on top of Card
  Services.  One special Card Services client, called Driver Services,
  provides a link betweek user level utility programs and the kernel
  facilities.

  The socket driver layer is loosely based on the Socket Services API.
  There are two socket driver modules.  The tcic module supports the
  Databook TCIC-2 family of host controllers.  The i82365 module
  supports the Intel i82365sl family and various Intel-compatible
  controllers, including Cirrus, VLSI, Ricoh, and Vadem chips.  In
  addition, the i82365 module implements support for CardBus controllers
  that follow the ``Yenta'' register-level specification.

  Card Services is the largest single component of the package.  It
  provides an API somewhat similar to DOS Card Services, adapted to a
  Unix environment.  The Linux implementation was based in part on the
  Solaris interface specification.  It is implemented in the pcmcia_core
  module.  Most version 2.1 features are implemented, with some PC Card
  95 features.

  The Driver Services layer implements a user mode pseudo-device for
  accessing some Card Services functions from utility programs.  It is
  responsible for keeping track of all client drivers, and for matching
  up drivers with physical sockets.  It is implemented in the ds module.

  This document describes the kernel interface to the Card Services and
  Driver Services modules, and the user interface to Driver Services.
  It is intended for use by client device driver developers.  The Linux
  PCMCIA-HOWTO describes how to install and use Linux PCMCIA support.
  It is available from  <http://pcmcia-cs.sourceforge.net>.

  1.1.  Copyright notice and disclaimer

  Copyright (c) 1996-2002 David A. Hinds

  This document may be reproduced or distributed in any form without my
  prior permission.  Modified versions of this document, including
  translations into other languages, may be freely distributed, provided
  that they are clearly identified as such, and this copyright is
  included intact.

  This document may be included in commercial distributions without my
  prior consent.  While it is not required, I would like to be informed
  of such usage.  If you intend to incorporate this document in a
  published work, please contact me to make sure you have the latest
  available version.
  This document is provided ``AS IS'', with no express or implied
  warranties.  Use the information in this document at your own risk.

  1.2.  Acknowledgements

  I'd like to thank all the Linux users who have helped test and debug
  this software, and who have helped with driver development.  I should
  also thank Linus Torvalds, Donald Becker, Alan Cox, and Bjorn Ekwall
  for Linux kernel development help.  I'm especially grateful to Michael
  Bender for many helpful discussions about the Solaris implementation.

  2.  Basic Concepts

  2.1.  The socket interface

  The PC Card bus has two basic operating modes: ``memory-only'' and
  ``memory and IO''.  The first mode was defined by the original Version
  1.0 specification and only supports simple memory cards.  The second
  mode, defined in Version 2.0, redefines a few of the memory card
  control signals to support IO port addressing and IO interrupt
  signalling.

  PC Card devices have two memory spaces: ``attribute memory'' and
  ``common memory''.  The interface can address up to 16MB of each type
  of memory.  Attribute memory is typically used for holding descriptive
  information and configuration registers.  Common memory may include
  the bulk storage of a memory card, or device buffers in the case of IO
  cards.  All cards that are compliant with the version 2.0 PC Card
  specification should have a Card Information Structure (or ``CIS'') in
  attribute memory, which describes the card and how it should be
  configured.

  Separate control signals allow cards to signal their operating status
  to the host.  These signals include card detect, ready/busy, write
  protect, battery low, and battery dead.

  The ``memory and IO'' interface mode allows cards to address up to 64K
  of IO ports.  It also allows cards to signal IO interrupts, and routes
  one card output to the host system's speaker.  In this mode, several
  of the memory card control signals are unavailable because those pins
  are used to carry the extra IO card signals.  On some cards, these
  signals can instead be read from a special configuration register in
  attribute memory, the ``Pin Replacement Register''.

  2.2.  The socket controller

  The socket controller serves as a bridge between PC Card devices and
  the system bus.  There are several varieties of controllers, but all
  share the same basic functionality.  The Socket Services software
  layer takes care of all the details of how to program the host
  controller.

  The socket controller has the job of mapping windows of addresses in
  the host memory and IO spaces to windows of addresses in card space.
  All supported controllers support at least four independent memory
  windows and two IO windows per socket.

  Each memory window is defined by a base address in the host address
  space, a base address in the card address space, and a window size.
  Some controllers differ in their alignment rules for memory windows,
  but all controllers will support windows whose size is at least 4K and
  also a power of two, and where the base address is a multiple of the
  window size.  Each window can be programmed to point to either
  attribute or common memory.

  IO windows differ from memory windows in that host addresses that fall
  within an IO window are not modified before they are passed on to an
  IO card.  Effectively, the base addresses of the window in the host
  and card address spaces are always equal.  IO windows also have no
  alignment or size restrictions; an IO window can start and end on any
  byte boundary in the 64K IO address space.

  The PC Card bus defines a single interrupt signal from the card to the
  controller.  The controller then has the responsibility of steering
  this interrupt to an appropriate interrupt request (``irq'') line.
  All controllers support steering card IO interrupts to essentially any
  free interrupt line.  Because steering happens in the controller, the
  card itself is unaware of which interrupt it uses.

  All PC Card controllers can generate interrupts in response to card
  status changes.  These interrupts are distinct from the IO interrupts
  generated by an IO card, and use a separate interrupt line.  Signals
  that can generate interrupts include card detect, ready/busy, write
  protect, battery low, and battery dead.

  3.  Card Services Subfunction Descriptions

  Card Services calls have the general form:

       #include "cs_types.h"
       #include "cs.h"

       int CardServices(int subfunc, void *arg1, void *arg2, ...);

  Some Card Services functions require additional #include statements.
  The particular subfunction determines the number of expected
  arguments.  A return code of CS_SUCCESS indicates that a call
  succeeded.  Other return codes indicate errors.

  3.1.  Client management functions

  Device drivers that use Card Services functions are called
  ``clients''.  A device driver should use the RegisterClient call to
  get a client handle before using other services.  Most Card Services
  functions will take this client handle as an argument.  Before
  unloading, drivers should also unregister with DeregisterClient.

  3.1.1.  RegisterClient

  int CardServices(RegisterClient, client_handle_t *client, client_reg_t *reg);

  The client_reg_t data structure is given by:

       typedef struct client_reg_t {
               dev_info_t      *dev_info;
               u_int           Attributes;
               u_int           EventMask;
               int             (*event_handler)(event_t event, int priority,
                                                event_callback_args_t *args);
               event_callback_args_t   event_callback_args;
               u_int           Version;
       } client_reg_t;

  RegisterClient establishes a link between a client driver and Card
  Services, and connects the client with an appropriate socket.  The
  dev_info parameter is used by Card Services to match the client with a
  socket and function; this correspondence is normally established by
  Driver Services via a call to BindDevice.  If successful, a client
  handle will be returned in client.

  The following flags can be specified in Attributes:

     INFO_MASTER_CLIENT
        For use only by the Driver Services client.  Among other things,
        specifies that this client should not be automatically unbound
        when a card is ejected from this socket.

     INFO_IO_CLIENT
        Specifies that this client is an IO card driver.

     INFO_MTD_CLIENT
        Specifies that this client is a Memory Technology Driver.

     INFO_MEM_CLIENT
        Specifies that this client is a memory card driver.

     INFO_CARD_SHARE
        Included for compatibility, has no effect.

     INFO_CARD_EXCL
        Included for compatibility, has no effect.

  EventMask specifies what events this client should be notified of.
  The event_handler entry point will be called by Card Services when an
  event in EventMask is processed.  The event_handler_args structure is
  a template for the structure that will be passed to the event handler.
  The Version parameter identifies the Card Services version level that
  this driver expects; it is currently ignored.

  A driver should be prepared to handle Card Services events before
  calling RegisterClient.  This call will always generate a
  CS_REGISTRATION_COMPLETE event, and may also generate an artificial
  CS_CARD_INSERTION event if the socket is currently occupied.

  Return codes:

     CS_OUT_OF_RESOURCE
        An appropriate socket could not be found for this driver.
  3.1.2.  DeregisterClient

       int CardServices(DeregisterClient, client_handle_t client);

  DeregisterClient severs the connection between a client and Card
  Services.  It should be called after the client has freed any
  resources it has allocated.  Once a connection is broken, it cannot be
  reestablished until after another call to BindDevice.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_IN_USE
        The client still has allocated resources, such as IO port
        windows or an interrupt, or the socket configuration is locked.

  3.1.3.  SetEventMask

       int CardServices(SetEventMask, client_handle_t client, eventmask_t *mask);

  The eventmask_t structure is given by:

       typedef struct eventmask_t {
               u_int           Attributes;
               u_int           EventMask;
       } eventmask_t;

  SetEventMask updates the mask that determines which events this client
  will be notified of.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

  3.1.4.  BindDevice

       int CardServices(BindDevice, bind_req_t *req);

  The bind_req structure is given by:

  typedef struct bind_req_t {
          socket_t        Socket;
          u_char          Function;
          dev_info_t      *dev_info;
  } bind_req_t;

  BindDevice associates a device driver with a particular socket.  It is
  normally called by Driver Services after a newly inserted card has
  been identified.  Once a driver has been bound to a socket, it will be
  eligible to register as a client of that socket.  Note that this call
  does not take a client handle as an argument.  This is the only Card
  Services call that takes a socket number as an argument.

  The Function field specifies which function(s) of a multifunction card
  are to be bound to this driver.  Function numbers correspond to
  entries in the card's CISTPL_LONGLINK_MFC tuple.  If Function is set
  to BIND_FN_ALL, the driver will be bound to all card functions.  A
  driver will only be able to access CIS tuples corresponding to
  functions for which it is bound.

  Return codes:

     CS_BAD_SOCKET
        The specified socket number is invalid.

  3.2.  Socket state control

  These functions are more or less concerned with getting and setting
  the current operating state of a socket.  GetStatus returns the
  current socket state.  ResetCard is used to send a hard reset signal
  to a socket.  SuspendCard and ResumeCard can be used to power down and
  power up a socket without releasing the drivers currently bound to
  that socket.  EjectCard and InsertCard essentially mimic real card
  ejection and insertion events.

  3.2.1.  GetStatus

       int CardServices(GetStatus, client_handle_t client, cs_status_t *status);

  The cs_status_t data structure is given by:

       typedef struct cs_status_t {
               u_char          Function;
               u_int           CardState;
               u_int           SocketState;
       } cs_status_t;

  GetStatus returns the current status of a client's socket.  For cards
  that are configured in IO mode, GetStatus uses the Pin Replacement
  Register and Extended Status Register to determine the card status.
  For normal clients, the Function field is ignored, but for clients
  bound with BIND_FN_ALL, this field specifies the function whose
  configuration registers should be used to determine the socket state,
  if the socket is currently configured.  The following flags are
  defined in CardState:

     CS_EVENT_CARD_DETECT
        Specifies that the socket is occupied.

     CS_EVENT_CB_DETECT
        Specifies that the socket is occupied by a CardBus device.

     CS_EVENT_WRITE_PROTECT
        Specifies that the card is currently write protected.

     CS_EVENT_BATTERY_LOW
        Specifies that the card battery is low.

     CS_EVENT_BATTERY_DEAD
        Specifies that the card battery is dead.

     CS_EVENT_READY_CHANGE
        Specifies that the card is ready.

     CS_EVENT_PM_SUSPEND
        Specifies that the socket is suspended.

     CS_EVENT_REQUEST_ATTENTION
        Specifies that the request attention bit in the extended status
        register is set.

     CS_EVENT_CARD_INSERTION
        Specifies that a card insertion event is in progress.  An
        insertion event will be sent to the client when socket setup is
        complete.

     CS_EVENT_3VCARD
        Indicates that the card supports 3.3V operation.

     CS_EVENT_XVCARD
        Indicates that the card supports ``X.X''V operation.  The actual
        voltage is currently undefined in the specification.

  SocketState is currently unused, but in theory, it should latch
  changes in the state of the fields in CardState.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

  3.2.2.  ResetCard

       int CardServices(ResetCard, client_handle_t client);

  ResetCard requests that a client's socket be reset.  When this call is
  made, Card Services sends all clients a CS_EVENT_RESET_REQUEST event.
  If any client rejects the request, Card Services sends the initiating
  client a CS_EVENT_RESET_COMPLETE event with event_callback_args.info
  set to the return code of the client that rejected the request.

  If all clients agree to the request, Card Services sends a
  CS_EVENT_RESET_PHYSICAL event, then resets the socket.  When the
  socket signals that it is ready, a CS_EVENT_CARD_RESET event is
  generated.  Finally, a CS_EVENT_RESET_COMPLETE event is sent to the
  initiating client, with event_callback_args.info set to zero.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_IN_USE
        This socket is currently being reset.

  3.2.3.  SuspendCard

       int CardServices(SuspendCard, client_handle_t client);

  Card Services sends all clients CS_EVENT_PM_SUSPEND events, then shuts
  down and turns off power to the socket.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_IN_USE
        This socket is already suspended.

  3.2.4.  ResumeCard

       int CardServices(ResumeCard, client_handle_t client);

  After restoring power to the socket, Card Services will notify all
  clients with CS_EVENT_PM_RESUME events.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_IN_USE
        This socket is not currently suspended.

  3.2.5.  EjectCard

       int CardServices(EjectCard, client_handle_t client);

  Card Services sends eject events to all clients, then shuts down and
  turns off power to the socket.  All clients except for Driver Services
  will be unlinked from the socket.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

  3.2.6.  InsertCard

       int CardServices(InsertCard, client_handle_t client);

  Card Services sends insertion events to all clients of this socket
  (normally, only Driver Services).

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_IN_USE
        The socket has already been configured.

  3.3.  IO card configuration calls

  The normal order of events is for a driver to reserve IO ports and an
  interrupt line with calls to RequestIO and RequestIRQ, then to call
  RequestConfiguration to actually configure the socket.  If any of
  these calls fails, a driver should be sure to release any resources it
  successfully reserved.

  Multifunction cards can have separate configurations for each card
  function.  However, the configurations do need to be consistent with
  one another.  While each card function has its own set of
  configuration registers, each socket has only a single interrupt line
  and can only map two contiguous ranges of IO ports.

  CardBus cards are configured somewhat differently.  The RequestIO and
  RequestConfiguration calls have similar roles, however, Card Services
  takes responsibility for most of the configuration details, and the
  contents of the request structures are ignored.

  3.3.1.  RequestIO

       int CardServices(RequestIO, client_handle_t client, io_req_t *req);

  The io_req_t data structure is given by:

       typedef struct io_req_t {
               ioaddr_t        BasePort1;
               ioaddr_t        NumPorts1;
               u_int           Attributes1;
               ioaddr_t        BasePort2;
               ioaddr_t        NumPorts2;
               u_int           Attributes2;
               u_int           IOAddrLines;
       } io_req_t;

  RequestIO reserves IO port windows for a card.  BasePort1 specifies
  the base IO port address of the window to be reserved.  If NumPorts2
  is non-zero, a second IO port window will also be reserved.
  IOAddrLines specifies the number of address lines that are actually
  decoded by the card.  The IO port allocation algorithm assumes that
  any alias of the requested address(es) that preserves the lower
  IOAddrLines bits will be acceptable, and will update BasePort1 and
  BasePort2 to reflect the address range(s) actually assigned.

  Prior to release 3.1.4, the IOAddrLines field was ignored.  The
  allocator always tried to assign the exact address range requested,
  unless the base address was zero; in that case, it would assign any
  available window aligned to the nearest power of two larger than the
  window size.  The new allocator verifies that the IOAddrLines
  parameter agrees with the requested window parameters, and defaults to
  the pre-3.1.4 behavior if an inconsistency is found.

  With multifunction cards, this call will allocate IO ports for each
  card function in such a way that all a card's ports can be mapped by
  the two low-level IO port windows associated with each physical
  socket.  For example, if the drivers for a hypothetical four-function
  card each attempt to allocate one IO window of 8 ports, Card Services
  will consolidate these into a single contiguous 32-port block.

  When this function is invoked by a CardBus client, the IO request
  structure is ignored.  Instead, Card Services examines the card and
  allocates any necessary system resources: this includes IO and memory
  space, as well as an interrupt, if needed.  One call will reserve all
  resources needed for all card functions, not just the function of the
  client making the call.

  This call does not actually configure a socket's IO windows: this is
  done by a subsequent call to RequestConfiguration.

  The following flags can be specified in Attributes1 and Attributes2:

     IO_DATA_PATH_WIDTH
        This field may either be IO_DATA_PATH_WIDTH_16 for 16-bit
        access, or IO_DATA_PATH_WIDTH_8 for 8-bit access, or
        IO_DATA_PATH_WIDTH_AUTO to dynamically size the bus based on the
        access size.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_IN_USE
        This socket's IO windows have already been reserved.

     CS_CONFIGURATION_LOCKED
        This socket's configuration has been locked by a call to
        RequestConfiguration.

     CS_BAD_ATTRIBUTE
        An unsupported attribute flag was specified.

     CS_UNSUPPORTED_FUNCTION
        For a CardBus client, this is returned if Card Services was not
        configured with CardBus support.

  3.3.2.  ReleaseIO

       int CardServices(ReleaseIO, client_handle_t client, io_req_t *req);

  ReleaseIO un-reserves IO port windows allocated by a previous call to
  RequestIO.  The req parameter should be the same one passed to
  RequestIO.  If several card functions are sharing a larger IO port
  window, ports released by one function may not become available for
  other uses until all card functions have released their IO ports.

  For a CardBus client, this call releases all system resources
  allocated for this card.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_CONFIGURATION_LOCKED
        This socket's configuration has been locked by a call to
        RequestConfiguration.  The configuration should be released
        before calling ReleaseIO.

     CS_BAD_ARGS
        The parameters in req do not match the parameters passed to
        RequestIO.

  3.3.3.  RequestIRQ

       int CardServices(RequestIRQ, client_handle_t client, irq_req_t *req);

  The irq_req_t structure is given by:

       typedef struct irq_req_t {
               u_int           Attributes;
               u_int           AssignedIRQ;
               u_int           IRQInfo1, IRQInfo2;
               void            *(Handler)(int, struct pt_regs *);
               void            *Instance
       } irq_req_t;

  RequestIRQ reserves an interrupt line for use by a card.  The IRQInfo1
  and IRQInfo2 fields correspond to the interrupt description bytes in a
  CFTABLE_ENTRY tuple.  If IRQ_INFO2_VALID is set in IRQInfo1, then
  IRQInfo2 is a bit-mapped mask of allowed interrupt values.  Each bit
  corresponds to one interrupt line: bit 0 = irq 0, bit 1 = irq 1, etc.
  So, a mask of 0x1100 would mean that interrupts 12 and 8 could be
  used.  If IRQ_INFO2_VALID is not set, IRQInfo1 is just the desired
  interrupt number.  If the call is successful, the reserved interrupt
  is returned in AssignedIRQ.

  If the IRQ_HANDLER_PRESENT flag is set, then this call also specifies
  an interrupt handler to be installed when the interrupt is enabled.
  When RequestConfiguration is called, the handler given by Handler will
  be installed.  For 2.0 and later kernels, the interrupt handler will
  be installed with the device ``instance'' given in Instance.  For
  pre-2.1.60 kernels, the kernel irq2dev_map table will also be updated.
  With multifunction cards, the interrupt will be allocated in shared
  mode, and the handler(s) have responsibility for determining which
  card function(s) require attention when an interrupt is received.  If
  a client instead bypasses Card Services to install its own interrupt
  service routine, it should allocate the interrupt in shared mode if
  this client could be bound to a multifunction card.

  The following flags can be specified in Attributes:

     IRQ_FORCED_PULSE
        Specifies that the interrupt should be configured for pulsed
        mode, rather than the default level mode.

     IRQ_TYPE_TIME
        Specifies that this interrupt can be time-shared with other Card
        Services drivers.  Only one driver should enable the interrupt
        at any time.

     IRQ_FIRST_SHARED
        In conjunction with IRQ_TYPE_TIME, this should be set by the
        first driver requesting a shared interrupt.
     IRQ_HANDLER_PRESENT
        Indicates that the Handler field points to an interrupt service
        routine that should be installed.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_IN_USE
        An interrupt has already been reserved for this socket, or the
        requested interrupt is unavailable.

     CS_CONFIGURATION_LOCKED
        This card function's configuration has been locked by a call to
        RequestConfiguration.

     CS_BAD_ATTRIBUTE
        An unsupported attribute flag was specified.

  3.3.4.  ReleaseIRQ

       int CardServices(ReleaseIRQ, client_handle_t client, irq_req_t *req);

  ReleaseIRQ un-reserves an interrupt assigned by an earlier call to
  RequestIRQ.  The req structure should be the same structure that was
  passed to RequestIRQ.  If a handler was specified in the RequestIRQ
  call, it will be unregistered at this time.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_CONFIGURATION_LOCKED
        This socket's configuration has been locked by a call to
        RequestConfiguration.  The configuration should be released
        before calling ReleaseIRQ.

     CS_BAD_IRQ
        The parameters in req do not match the parameters passed to
        RequestIRQ.

  3.3.5.  RequestConfiguration

       int CardServices(RequestConfiguration, client_handle_t client, config_req_t *req);

  The config_req_t structure is given by:

  typedef struct config_req_t {
          u_int           Attributes;
          u_int           Vcc, Vpp1, Vpp2;
          u_int           IntType;
          u_int           ConfigBase;
          u_char          Status, Pin, Copy, ExtStatus;
          u_char          ConfigIndex;
          u_int           Present;
  } config_req_t;

  RequestConfiguration is responsible for actually configuring a socket.
  This includes setting voltages, setting CIS configuration registers,
  setting up IO port windows, and setting up interrupts.

  IntType specifies the type of interface to use for this card.  It may
  be INT_MEMORY, INT_MEMORY_AND_IO, or INT_CARDBUS.  Voltages are
  specified in units of 1/10 volt.  Currently, Vpp1 must equal Vpp2.

  With multifunction cards, each card function is configured separately.
  Each function has its own set of CIS configuration registers.
  However, all functions must be configured with the same power and
  interface settings.

  When invoked by a CardBus client, most of the request structure is
  ignored, and all card functions will be configured based on data
  collected in a previous RequestIO call.  This includes configuring the
  CardBus bridge, as well as initializing the Command, Base Address, and
  Interrupt Line registers in each card function's configuration space.
  IntType must be set to INT_CARDBUS in this case.

  The following flags can be specified in Attributes.  DMA and speaker
  control are not supported on all systems.

     CONF_ENABLE_IRQ
        Enable the IO interrupt reserved by a previous call to
        RequestIRQ.

     CONF_ENABLE_DMA
        Enable DMA accesses for this socket.

     CONF_ENABLE_SPKR
        Enable speaker output from this socket.

  The Present parameter is a bit map specifying which CIS configuration
  registers are implemented by this card.  ConfigBase gives the offset
  of the configuration registers in attribute memory.  The following
  registers can be specified:

     PRESENT_OPTION
        Specifies that the Configuration Option Register is present.
        The COR register will be set using the ConfigIndex parameter.

     PRESENT_STATUS
        Specifies that the Card Configuration and Status Register is
        present.  The CCSR will be initialized with the Status
        parameter.

     PRESENT_PIN_REPLACE
        Specifies that the Pin Replacement Register is present.  The PRR
        will be initialized with the Pin parameter.

     PRESENT_COPY
        Specifies that the Socket and Copy Register is present.  The SCR
        will be initialized with the Copy parameter.

     PRESENT_EXT_STATUS
        Specifies that the Extended Status Register is present.  The ESR
        will be initialized with the ExtStatus parameter.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_OUT_OF_RESOURCE
        Card Services was unable to allocate a memory window to access
        the card's configuration registers.

     CS_CONFIGURATION_LOCKED
        This card's configuration has already been locked by another
        call to RequestConfiguration.

     CS_BAD_VCC
        The requested Vcc voltage is not supported.

     CS_BAD_VPP
        The requested Vpp1/Vpp2 voltage is not supported.

     CS_UNSUPPORTED_MODE
        A non-CardBus client attempted to configure a CardBus card, or a
        CardBus client attempted to configure a non-CardBus card.

  3.3.6.  ModifyConfiguration

       int CardServices(ModifyConfiguration, client_handle_t client, modconf_t *mod);

  The modconf_t structure is given by:

       typedef struct modconf_t {
               u_int           Attributes;
               u_int           Vcc, Vpp1, Vpp2;
       } modconf_t;

  ModifyConfiguration modifies some attributes of a socket that has been
  configured by a call to RequestConfiguration.

  The following flags can be specified in Attributes:

     CONF_IRQ_CHANGE_VALID
        Indicates that the CONF_ENABLE_IRQ setting should be updated.

     CONF_ENABLE_IRQ
        Specifies that IO interrupts should be enabled for this socket.

     CONF_VCC_CHANGE_VALID
        Indicates that Vcc should be updated.

     CONF_VPP1_CHANGE_VALID
        Indicates that Vpp1 should be updated.

     CONF_VPP2_CHANGE_VALID
        Indicates that Vpp2 should be updated.

  Currently, Vpp1 and Vpp2 must always have the same value.  So, the two
  values must always be changed at the same time.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_CONFIGURATION_LOCKED
        This actually means that this socket has not been locked.

     CS_BAD_VCC
        The requested Vcc voltage is not supported.

     CS_BAD_VPP
        The requested Vpp1/Vpp2 voltage is not supported.

  3.3.7.  ReleaseConfiguration

       int CardServices(ReleaseConfiguration, client_handle_t client, config_req_t *req);

  ReleaseConfiguration un-configures a socket previously set up by a
  call to RequestConfiguration.  The req parameter should be the same
  one used to configure the socket.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid, or the socket is not configured.

  3.3.8.  GetConfigurationInfo

       int CardServices(GetConfigurationInfo, client_handle_t client, config_info_t *config);

  The config_info_t structure is given by:

  typedef struct config_info_t {
          u_char          Function;
          u_int           Attributes;
          u_int           Vcc, Vpp1, Vpp2;
          u_int           IntType;
          u_int           ConfigBase;
          u_char          Status, Pin, Copy, Option, ExtStatus;
          u_int           Present;
          u_int           AssignedIRQ;
          u_int           IRQAttributes;
          ioaddr_t        BasePort1;
          ioaddr_t        NumPorts1;
          u_int           Attributes1;
          ioaddr_t        BasePort2;
          ioaddr_t        NumPorts2;
          u_int           Attributes2;
          u_int           IOAddrLines;
  } config_info_t;

  GetConfigurationInfo returns the current socket configuration as it
  was set up by RequestIO, RequestIRQ, and RequestConfiguration.  Most
  fields will only be filled in if the socket is fully configured; the
  CONF_VALID_CLIENT flag in Attributes indicates this fact.  For normal
  clients bound to a single card function, the Function field is
  ignored, and data for that client's assigned function is returned.
  For clients bound to BIND_FN_ALL, this field specifies which
  function's configuration data should be returned.

  For CardBus cards, the ConfigBase field is set to the card's PCI
  vendor/device ID, and the Option field is set to the CardBus PCI bus
  number.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid, or the socket is not configured.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_CONFIGURATION_LOCKED
        This actually means that the configuration has not been locked.

  3.4.  Card Information Structure (CIS) calls

  The definition of the Card Information Structure (CIS) is the darkest
  chapter of the PC Card standard.  All version 2 compliant cards should
  have a CIS, which describes the card and how it should be configured.
  The CIS is a linked list of ``tuples'' in the card's attribute memory
  space.  Each tuple consists of an identification code, a length byte,
  and a series of data bytes.  The layout of the data bytes for some
  tuple types is absurdly complicated, in an apparent effort to use
  every last bit.

  The ValidateCIS call checks to see if a card has a reasonable CIS.
  The GetFirstTuple and GetNextTuple calls are used to step through CIS
  tuple lists.  GetTupleData extracts data bytes from a tuple.  And
  ParseTuple unpacks most tuple types into more easily used forms.
  Finally, the ReplaceCIS call allows a client to provide Card Services
  with a substitute for the CIS found on the card.

  3.4.1.  GetFirstTuple, GetNextTuple

       #include "cistpl.h"

       int CardServices(GetFirstTuple, client_handle_t client, tuple_t *tuple);
       int CardServices(GetNextTuple, client_handle_t client, tuple_t *tuple);

  The tuple_t data structure is given by:

       typedef struct tuple_t {
               u_int           Attributes;
               cis_data_t      DesiredTuple;
               u_int           Flags;
               cisdata_t       TupleCode;
               u_int           TupleLink;
               cisdata_t       TupleOffset;
               cisdata_t       TupleDataMax;
               cisdata_t       TupleDataLen;
               cisdata_t       *TupleData;
       } tuple_t;

  GetFirstTuple searches a card's CIS for the first tuple code matching
  DesiredTuple.  The special code RETURN_FIRST_TUPLE will match the
  first tuple of any kind.  If successful, TupleCode is set to the code
  of the first matching tuple found, and TupleLink is the address of
  this tuple in attribute memory.

  GetNextTuple is like GetFirstTuple, except that given a tuple_t
  structure returned by a previous call to GetFirstTuple or
  GetNextTuple, it will return the next tuple matching DesiredTuple.

  These functions will automatically traverse any link tuples found in
  the CIS.  For multifunction cards having a CISTPL_LONGLINK_MFC tuple,
  these functions will automatically follow just the CIS chain specific
  to a client driver's assigned function.  If a client was bound to
  BIND_FN_ALL, then all tuples will be returned.

  The following flags can be specified in Attributes:

     TUPLE_RETURN_LINK
        Indicates that link tuples (CISTPL_LONGLINK_A,
        CISTPL_LONGLINK_C, CISTPL_LONGLINK_MFC, CISTPL_NOLINK,
        CISTPL_LINKTARGET) should be returned.  Normally these tuples
        are processed silently.

     TUPLE_RETURN_COMMON
        Indicates that tuples in the ``common'' CIS section of a
        multifunction CIS should be returned.  In the absence of this
        flag, normally, Card Services will only return tuples specific
        to the function bound to the client.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_OUT_OF_RESOURCE
        Card Services was unable to set up a memory window to map the
        card's CIS.

     CS_NO_MORE_ITEMS
        There were no tuples matching DesiredTuple.

  3.4.2.  GetTupleData

       #include "cistpl.h"

       int CardServices(GetTupleData, client_handle_t client, tuple_t *tuple);

  GetTupleData extracts a series of data bytes from the specified tuple,
  which must have been returned by a previous call to GetFirstTuple or
  GetNextTuple.  A maximum of TupleDataMax bytes will be copied into the
  TupleData buffer, starting at an offset of TupleOffset bytes.  The
  number of bytes copied is returned in TupleDataLen.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_OUT_OF_RESOURCE
        Card Services was unable to set up a memory window to map the
        card's CIS.

     CS_NO_MORE_ITEMS
        The tuple does not contain any more data.  TuppleOffset is
        greater than or equal to the length of the tuple.

  3.4.3.  ParseTuple

       #include "cistpl.h"

       int CardServices(ParseTuple, client_handle_t client, tuple_t *tuple, cisparse_t *parse);

  The cisparse_t data structure is given by:

  typedef union cisparse_t {
          cistpl_device_t         device;
          cistpl_checksum_t       checksum;
          cistpl_longlink_t       longlink;
          cistpl_longlink_mfc_t   longlink_mfc;
          cistpl_vers_1_t         version_1;
          cistpl_altstr_t         altstr;
          cistpl_jedec_t          jedec;
          cistpl_manfid_t         manfid;
          cistpl_funcid_t         funcid;
          cistpl_config_t         config;
          cistpl_cftable_entry_t  cftable_entry;
          cistpl_device_geo_t     device_geo;
          cistpl_vers_2_t         version_2;
          cistpl_org_t            org;
          cistpl_format_t         format;
  } cisparse_t;

  ParseTuple interprets tuple data returned by a previous call to
  GetTupleData.  The structure returned depends on the type of the
  parsed tuple.  See the cistpl.h file for these structure definitions;
  some of them are quite complex.

  Return codes:

     CS_BAD_TUPLE
        An error was encounted during parsing of this tuple.  The tuple
        may be incomplete, or may be formatted incorrectly.

     CS_UNSUPPORTED_FUNCTION
        ParseTuple cannot parse the specified tuple type.

  3.4.4.  ValidateCIS

       int CardServices(ValidateCIS, client_handle_t client, cisinfo_t *cisinfo);

  The cisinfo_t structure is given by:

       typedef struct cisinfo_t {
               u_int           Chains;
       } cisinfo_t;

  ValidateCIS attempts to verify that a card has a reasonable Card
  Information Structure.  It returns the number of tuples found in
  Chains.  If the CIS appears to be uninterpretable, Chains will be set
  to 0.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_OUT_OF_RESOURCE
        Card Services was unable to set up a memory window to map the
        card's CIS.

  3.4.5.  ReplaceCIS

       int CardServices(ReplaceCIS, client_handle_t client, cisdump_t *cisinfo);

  The cisdump_t structure is given by:

       typedef struct cisdump_t {
               u_int           Length;
               cisdata_t       Data[CISTPL_MAX_CIS_SIZE];
       } cisinfo_t;

  ReplaceCIS allows a client to pass Card Services a replacement for the
  CIS found on a card.  Its intended application is for cards with
  incomplete or inaccurate CIS information.  If a correct CIS can be
  deduced from other information available for the card, this allows
  that information to be provided to clients in a clean fashion.  The
  alternative is to pollute client source code with fixes targeted for
  each card with a CIS error.  The replacement CIS remains in effect
  until the card is ejected, and all tuple-related services will use the
  replacement instead of the card's actual CIS.

  The Length field gives the number of bytes of CIS data in the Data
  array.  The Data array can be considered to be just the even bytes of
  a card's attribute memory.  It should contain all required features of
  a normal CIS, including an initial CISTPL_DEVICE tuple and a final
  CISTPL_END tuple.  Long links (including CISTPL_LONGLINK_MFC) may be
  used: all target addresses are interpreted in the replacement CIS
  space.  In general, a replacement CIS should also contain the same
  basic identification tuples (CISTPL_MANFID, CISTPL_VERS_1) as the
  original card.

  This service was added in release 3.0.1.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_OUT_OF_RESOURCE
        Card Services was unable to allocate memory to hold the
        replacement CIS.

  3.5.  Memory window control

  Each socket can have up to four active memory windows, mapping
  portions of card memory into the host system address space.  A PC Card
  device can address at most 16MB of both common and attribute memory.
  Windows should typically be sized to a power of two.  Depending on
  socket capabilities, they may need to be aligned on a boundary that is
  a multiple of the window size in both the host and card address
  spaces.

  A memory window is initialized by a call to RequestWindow.  Some
  window attributes can be modified using ModifyWindow.  The segment of
  card memory mapped to the window can be modified using MapMemPage.
  And windows are released with ReleaseWindow.  Unlike almost all other
  Card Services subfunctions, the memory window functions normally act
  on window_handle_t handles, rather than client_handle_t handles.

  3.5.1.  RequestWindow

       int CardServices(RequestWindow, client_handle_t *handle, win_req_t *req);

  The win_req_t structure is given by:

       typedef struct win_req_t {
               u_int           Attributes;
               u_long          Base;
               u_int           Size;
               u_int           AccessSpeed;
       } win_req_t;

  RequestWindow maps a window of card memory into system memory.  On
  entry, the handle parameter should point to a valid client handle.  On
  return, this will be replaced by a window_handle_t handle that should
  be used in subsequent calls to ModifyWindow, MapMemPage, and
  ReleaseWindow.

  The following flags can be specified in Attributes:

     WIN_MEMORY_TYPE
        This field can be either WIN_MEMORY_TYPE_CM for common memory,
        or WIN_MEMORY_TYPE_AM for attribute memory.

     WIN_DATA_WIDTH
        Either WIN_DATA_WIDTH_16 for 16-bit accesses, or
        WIN_DATA_WIDTH_8 for 8-bit access.

     WIN_ENABLE
        If this is set, the window is turned on.

     WIN_USE_WAIT
        Specifies that the controller should observe the card's MWAIT
        signal.

     WIN_MAP_BELOW_1MB
        Requests that the window be mapped below the 1MB address
        boundary.  This may not be possible on some platforms.

     WIN_STRICT_ALIGN
        Requests that the window base be aligned to a multiple of the
        window size.  Added in release 3.1.2.

  Base specifies the base physical address of the window in system
  memory.  If zero, Card Services will set Base to the first available
  window address.  Size specifies the window size in bytes.  If zero,
  Card Services will set Size to the smallest window size supported by
  the host controller.  AccessSpeed specifies the memory access speed,
  in nanoseconds.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_CARD
        The socket assigned to this client is currently vacant.

     CS_BAD_ATTRIBUTE
        An unsupported window attribute was requested.

     CS_OUT_OF_RESOURCE
        The maximum number of memory windows for this socket are already
        being used.

     CS_IN_USE
        RequestWindow was unable to find a free window of system memory.

     CS_BAD_SIZE
        ,

     CS_BAD_BASE
        Either Base or Size does not satisfy the alignment rules for
        this socket.

  3.5.2.  ModifyWindow

       int CardServices(ModifyWindow, window_handle_t handle, modwin_t *mod);

  The modwin_t structure is given by:

       typedef struct modwin_t {
               u_int           Attributes;
               u_int           AccessSpeed;
       } modwin_t;

  ModifyWindow modifies the attributes of a window handle returned by a
  previous call to RequestWindow.  The following attributes can be
  changed:

     WIN_MEMORY_TYPE
        This field can be either WIN_MEMORY_TYPE_CM for common memory,
        or WIN_MEMORY_TYPE_AM for attribute memory.

     WIN_DATA_WIDTH
        Either WIN_DATA_WIDTH_16 for 16-bit accesses, or
        WIN_DATA_WIDTH_8 for 8-bit access.

     WIN_ENABLE
        If this is set, the window is turned on.

  AccessSpeed gives the new memory access speed, in nanoseconds.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid.

  3.5.3.  ReleaseWindow

       int CardServices(ReleaseWindow, window_handle_t handle);

  ReleaseWindow releases a memory window previously allocated with
  RequestWindow.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid.

  3.5.4.  GetFirstWindow, GetNextWindow

       int CardServices(GetFirstWindow, client_handle_t *client, win_req_t *req);
       int CardServices(GetNextWindow, window_handle_t *handle, win_req_t *req);

  These calls sequentially retrieve window configuration information for
  all of a socket's memory windows.  GetFirstWindow replaces the client
  window handle with a memory window handle, which will in turn be
  updated by calls to GetNextWindow.

  These services were added in release 3.1.0.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_MORE_ITEMS
        No more windows ara configured for this socket.

  3.5.5.  MapMemPage, GetMemPage

       int CardServices(MapMemPage, window_handle_t handle, memreq_t *req);
       int CardServices(GetMemPage, window_handle_t handle, memreq_t *req);

  The memreq_t structure is given by:

       typedef struct memreq_t {
               u_int           CardOffset;
               page_t          Page;
       } memreq_t;

  MapMemPage sets the address of card memory that is mapped to the base
  of a memory window to CardOffset.  The window should have been created
  by a call to RequestWindow.  The Page parameter is not implemented in
  this version and should be set to 0.  In turn GetMemPage retrieves the
  current card address mapping for a memory window.

  The GetMemPage service was added in release 3.1.0.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid.

     CS_BAD_PAGE
        The Page value was non-zero.

     CS_BAD_OFFSET
        The requested CardOffset was out of range or did not have proper
        alignment.

  3.6.  Bulk Memory Services

  Bulk memory services provide a higher level interface for accessing
  memory regions than that provided by the memory window services.  A
  client using bulk memory calls does not need to know anything about
  the underlying memory organization or access methods.  The device-
  specific code is packaged into a special Card Services client called a
  Memory Technology Driver.

  3.6.1.  RegisterMTD

       int CardServices(RegisterMTD, client_handle_t handle, mtd_reg_t *reg);

  The mtd_reg_t data structure is given by:

       typedef union mtd_reg_t {
               u_int           Attributes;
               u_int           Offset;
               u_long          MediaID;
       } mtd_reg_t;

  RegisterMTD informs Card Services that this client MTD will handle
  requests for a specified memory region.  The Offset field specifies
  the starting address of the memory region.  The following fields are
  defined in Attributes:

     REGION_TYPE
        Either REGION_TYPE_CM for common memory, or REGION_TYPE_AM for
        attribute memory.

  The MediaID field is recorded by Card Services, and will be passed to
  the MTD as part of any request that references this memory region.

  Once an MTD is bound to a memory region by a call to RegisterMTD, it
  will remain bound until the MTD calls DeregisterClient.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_BAD_OFFSET
        Either the offset does not match a valid memory region for this
        card, or another MTD has already registered for this region.

  3.6.2.  GetFirstRegion, GetNextRegion

       int CardServices(GetFirstRegion, client_handle_t handle, region_info_t *region);
       int CardServices(GetNextRegion, client_handle_t handle, region_info_t *region);

  The region_info_t data structure is given by:

       typedef union region_info_t {
               u_int           Attributes;
               u_int           CardOffset;
               u_int           RegionSize;
               u_int           AccessSpeed;
               u_int           BlockSize;
               u_int           PartMultiple;
               u_char          JedecMfr, JedecInfo;
               memory_handle_t next;
       } region_info_t;

  GetFirstRegion and GetNextRegion summarize the information in a card's
  CISTPL_DEVICE, CISTPL_JEDEC, and CISTPL_DEVICE_GEO tuples.  CardOffset
  gives the starting address of a region. RegionSize gives the length of
  the region in bytes.  AccessSpeed gives the device's cycle time in
  nanoseconds.  BlockSize gives the erase block size in bytes, and
  PartMultiple gives the minimum granularity of partitions on this
  device, in units of BlockSize.  JedecMfr and JedecInfo give the JEDEC
  identification bytes for this region.

  The following fields are defined in Attributes:

     REGION_TYPE
        Either REGION_TYPE_CM for common memory, or REGION_TYPE_AM for
        attribute memory.

  When these calls are made by an MTD client, only regions that have
  been bound to this client through calls to BindMTD will be returned.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_NO_MORE_ITEMS
        No more memory regions are defined.

  3.6.3.  OpenMemory

       int CardServices(OpenMemory, client_handle_t *handle, open_mem_t *req);

  The open_mem_t structure is given by:

       typedef struct open_mem_t {
               u_int           Attributes;
               u_int           Offset;
       } open_mem_t;

  OpenMemory is used to obtain a handle for accessing a memory region
  via the other bulk memory services.  The Offset field specifies the
  base address of the region to be accessed.  If successful, the client
  handle argument is replaced by the new memory handle.

  The following fields are defined in Attributes:

     MEMORY_TYPE
        Either MEMORY_TYPE_CM for common memory, or MEMORY_TYPE_AM for
        attribute memory.

     MEMORY_EXCLUSIVE
        Specifies that this client should have exclusive access to this
        memory region.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid.

     CS_BAD_OFFSET
        Either the offset does not specify a valid region, or the region
        does not have an associated MTD to service bulk memory requests.

  3.6.4.  CloseMemory

       int CardServices(CloseMemory, memory_handle_t handle);

  CloseMemory releases a memory handle returned by a previous call to
  OpenMemory.  A client should release all memory handles before calling
  DeregisterClient.

  Return codes:

     CS_BAD_HANDLE
        The memory handle is invalid.

  3.6.5.  ReadMemory, WriteMemory

       int CardServices(ReadMemory, memory_handle_t handle mem_op_t *req, caddr_t buf);
       int CardServices(WriteMemory, memory_handle_t handle, mem_op_t *req, caddr_t buf);

  The mem_io_t structure is given by:

       typedef struct mem_op_t {
               u_int           Attributes;
               u_int           Offset;
               u_int           Count;
       } mem_op_t;

  ReadMemory and WriteMemory read from and write to a card memory area
  defined by the specified memory handle, returned by a previous call to
  OpenMemory.  The Offset field gives the offset of the operation from
  the start of the card memory region.  The Count field gives the number
  of bytes to be transferred.  The buf field points to a host memory
  buffer to be the destination for a ReadMemory operation, or the source
  for a WriteMemory operation.

  The following fields are defined in Attributes:

     MEM_OP_BUFFER
        Either MEM_OP_BUFFER_USER if the host buffer is in a user memory
        segment, or MEM_OP_BUFFER_KERNEL if the host buffer is in kernel
        memory.

     MEM_OP_DISABLE_ERASE
        Specifies that a card area should not be erased before it is
        written.

     MEM_OP_VERIFY
        Specifies verification of write operations.

  Return codes:

     CS_BAD_HANDLE
        The window handle is invalid.

     CS_BAD_OFFSET
        The specified card offset is beyond the end of the memory
        region.

     CS_BAD_SIZE
        The specified transfer size extends past the end of the memory
        region.

  3.6.6.  RegisterEraseQueue

       int CardServices(RegisterEraseQueue, client_handle_t *handle, eraseq_hdr_t *header);

  The eraseq_hdr_t structure is given by:

       typedef struct erase_queue_header_t {
               int             QueueEntryCount;
               eraseq_entry_t  *QueueEntryArray;
       } eraseq_hdr_t;

  This call registers a queue of erase requests with Card Services.  An
  eraseq_handle_t handle will be returned in *handle.  When this client
  calls CheckEraseQueue, Card Services will scan the queue and begin
  asynchronous processing of any new requests.

  The eraseq_entry_t structure is given by:

       typedef struct eraseq_entry_t {
               memory_handle_t Handle;
               u_char          State;
               u_int           Size;
               u_int           Offset;
               void            *Optional;
       } eraseq_entry_t;

  In an erase queue entry, the Header field should be a memory handle
  returned by a previous call to OpenMemory.  The State field indicates
  the state of the erase request.  The following values are defined:

     ERASE_QUEUED
        Set by the client to indicate that this is a new request.

     ERASE_IDLE
        Set by the client to indicate that this entry is not active.

     ERASE_PASSED
        Set by the MTD to indicate successful completion.

     ERASE_FAILED
        Set by the MTD to indicate that the erase failed.

     ERASE_MEDIA_WRPROT
        Indicates that the region is write protected.

     ERASE_NOT_ERASABLE
        Indicates that this region does not support erase operations.

     ERASE_BAD_OFFSET
        Indicates that the erase does not start on an erase block
        boundary.

     ERASE_BAD_SIZE
        Indicates that the requested erase size is not a multiple of the
        erase block size.

     ERASE_BAD_SOCKET
        Set by the MTD to indicate that there is no card present.

  Additionally, the macro ERASE_IN_PROGRESS() will return a true
  condition for values of State that indicate an erase is being
  processed.

  The Size field gives the size of the erase request in bytes.  The
  Offset field gives the offset from the start of the region.  The size
  and offset should be aligned to erase block boundaries.  The Optional
  field is not used by Card Services and may be used by the client
  driver.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

  3.6.7.  DeregisterEraseQueue

       int CardServices(DeregisterEraseQueue, eraseq_handle_t handle);

  DeregisterEraseQueue frees a queue previously registered by a call to
  RegisterEraseQueue.  If there are any pending requests in the
  specified queue, the call will fail.

  Return codes:

     CS_BAD_HANDLE
        The erase queue handle is invalid.

     CS_BUSY
        The erase queue has erase requests pending.

  3.6.8.  CheckEraseQueue

       int CardServices(CheckEraseQueue, eraseq_handle_t handle);

  This call notifies Card Services that there are new erase requests in
  a queue previously registered with RegisterEraseQueue.

  Typically, a client will initially assign each erase queue entry the
  state value ERASE_IDLE.  When new requests are added to the queue, the
  client will set their states to ERASE_QUEUED, and call
  CheckEraseQueue.  When the client is notified of an erase completion
  event, it will check the state field to determine whether the request
  was successful.

  Return codes:

     CS_BAD_HANDLE
        The erase queue handle is invalid.

  3.7.  Miscellaneous calls

  3.7.1.  GetCardServicesInfo

       int CardServices(GetCardServicesInfo, servinfo_t *info);

  The servinfo_t structure is given by:

       typedef struct servinfo_t {
               char            Signature[2];
               u_int           Count;
               u_int           Revision;
               u_int           CSLevel;
               char            *VendorString;
       } servinfo_t;

  GetCardServicesInfo returns revision information about this version of
  Card Services.  Signature is set to ``CS''.  Count is set to the
  number of sockets currently configured.  Revision is set to the
  revision level of the Card Services package, and CSLevel is set to the
  level of compliance with the PC Card standard.  These are encoded as
  BCD numbers.  VendorString is set to point to an RCS identification
  string.

  This call always succeeds.

  3.7.2.  AccessConfigurationRegister

       #include "cisreg.h"

       int CardServices(AccessConfigurationRegister, client_handle_t handle, conf_reg_t *reg);

  The conf_reg_t structure is given by:
       typedef struct conf_reg_t {
               u_char          Function;
               u_int           Action;
               off_t           Offset;
               u_int           Value;
       } conf_reg_t;

  For normal clients bound to a specific card function, the Function
  field is ignored.  For clients bound to BIND_FN_ALL, this field
  specifies which function's configuration registers should be accessed.

  The Action parameter can be one of the following:

     CS_READ
        Read the specified configuration register and return Value.

     CS_WRITE
        Write Value to the specified configuration register.

  AccessConfigurationRegister either reads or writes the one-byte CIS
  configuration register at offset Offset from the start of the config
  register area.  It can only be used for a socket that has been
  configured with RequestConfiguration.

  The following values for Offset are defined in cistpl.h:

     CISREG_COR
        The Configuration Option Register.

     CISREG_CCSR
        The Card Configuration and Status Register.

     CISREG_PRR
        The Pin Replacement Register.

     CISREG_SCR
        The Socket and Copy Register.

     CISREG_ESR
        The Extended Status Register.

     CISREG_IOBASE0..CISREG_IOBASE3
        The I/O Base Registers.

     CISREG_IOSIZE
        The I/O Size Register.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_BAD_ARGS
        The specified Action is not supported.

     CS_CONFIGURATION_LOCKED
        This actually means that the configuration has not been locked.

     CS_OUT_OF_RESOURCE
        Card Services was unable to allocate a memory window to access
        the card's configuration registers.

  3.7.3.  AdjustResourceInfo

       int CardServices(AdjustResourceInfo, client_handle_t handle, adjust_t *adj);

  The adjust_t structure is given by:

       typedef struct adjust_t {
               u_int           Action;
               u_int           Resource;
               u_int           Attributes;
               union {
                       struct memory {
                               u_long          Base;
                               u_long          Size;
                       } memory;
                       struct io {
                               ioaddr_t        BasePort;
                               ioaddr_t        NumPorts;
                               u_int           IOAddrLines;
                       } io;
                       struct irq {
                               u_int           IRQ;
                       } irq;
               } resource;
       } adjust_t;

  AdjustResourceInfo is used to tell Card Services what resources may or
  may not be allocated by PC Card devices.  The normal Linux resource
  management systems (the *_region calls for IO ports, interrupt
  allocation) are respected by Card Services, but this call gives the
  user another level of control.

  The Action parameter can have the following values:

     ADD_MANAGED_RESOURCE
        Place the specified resource under Card Services control, so
        that it may be allocated by PC Card devices.

     REMOVE_MANAGED_RESOURCE
        Remove the specified resource from Card Services control.

  At initialization time, Card Services assumes that it can use all
  available interrupts, but IO ports and memory regions must be
  explicitly enabled with ADD_MANAGED_RESOURCE.

  The Resource parameter can have the following values:

     RES_MEMORY_RANGE
        Specifies a memory range resource, described by
        adj->resource.memory.

     RES_IO_RANGE
        Specifies an IO port resource, described by adj->resource.io.

     RES_IRQ
        Specifies an interrupt resource, described by adj->resource.irq.

  The following flags may be specified in Attributes:

     RES_RESERVED
        Indicates that the resource should be reserved for PC Card
        devices that specifically request it.  The resource will not be
        allocated for a device that asks Card Services for any available
        location.  This is not implemented yet.

  Return codes:

     CS_UNSUPPORTED_FUNCTION
        The specified Action or Resource is not supported.

     CS_BAD_BASE
        The specified IO address is out of range.

     CS_BAD_SIZE
        The specified memory or IO window size is out of range.

     CS_IN_USE
        The specified interrupt is currently allocated by a Card
        Services client.

  3.7.4.  ReportError

       int CardServices(ReportError, client_handle_t handle, error_info_t *err);

  The error_info_t structure is given by:

       typedef struct error_info_t {
               int             func;
               int             retcode;
       } error_info_t;

  ReportError generates a kernel error message given a Card Services
  function code and its return code.  If the client handle is valid,
  then the error will be prefixed with the client driver's name.  For
  example:

       error_info_t err = { RequestIO, CS_BAD_HANDLE };
       CardServices(ReportError, handle, &err);

  could generate the following message:

       serial_cs: RequestIO: Bad handle

  This call always succeeds.

  4.  Card Information Structure Definitions

  4.1.  CIS Tuple Definitions

  The Card Services ParseTuple function interprets raw CIS tuple data
  from a call to GetTupleData and returns the tuple contents in a form
  dependant on the tuple type.  This section describes the parsed tuple
  contents.

       #include "cistpl.h"

  4.1.1.  CISTPL_CHECKSUM

  The cistpl_checksum_t structure is given by:

       typedef struct cistpl_checksum_t {
               u_short         addr;
               u_short         len;
               u_char          sum;
       } cistpl_checksum_t;

  4.1.2.  CISTPL_NOLINK CISTPL_LONGLINK_A, CISTPL_LONGLINK_C,
  CISTPL_LINKTARGET,

  The cistpl_longlink_t structure is given by:

       typedef struct cistpl_longlink_t {
               u_int           addr;
       } cistpl_longlink_t;

  These tuples are pointers to additional chains of CIS tuples, either
  in attribute or common memory.  Each CIS tuple chain can have at most
  one long link.  CISTPL_LONGLINK_A tuples point to attribute memory,
  and CISTPL_LONGLINK_C tuples point to common memory.  The standard CIS
  chain starting at address 0 in attribute memory has an implied long
  link to address 0 in common memory.  A CISTPL_NOLINK tuple can be used
  to cancel this default link.

  The first tuple of a chain pointed to by a long link must be a
  CISTPL_LINKTARGET.  The CS tuple handling code will automatically
  follow long links and verify link targets; these tuples are normally
  invisible unless the TUPLE_RETURN_LINK attribute is specified in
  GetNextTuple.

  4.1.3.  CISTPL_LONGLINK_MFC

  The cistpl_longlink_mfc_t structure is given by:

       typedef struct cistpl_longlink_mfc_t {
               int     nfn;
               struct {
                       u_char  space;
                       u_int   addr;
               } fn[CISTPL_MAX_FUNCTIONS;
       } cistpl_longlink_mfc_t;

  This tuple identifies a multifunction card, and specifies long link
  pointers to CIS chains specific for each function.  The space field is
  either CISTPL_MFC_ATTR or CISTPL_MFC_COMMON for attribute or common
  memory space.

  4.1.4.  CISTPL_DEVICE, CISTPL_DEVICE_A

  The cistpl_device_t structure is given by:

       typedef struct cistpl_device_t {
               int             ndev;
               struct {
                       u_char          type;
                       u_char          wp;
                       u_int           speed;
                       u_int           size;
               } dev[CISTPL_MAX_DEVICES];
       } cistpl_device_t;

  The CISTPL_DEVICE tuple describes address regions in a card's common
  memory.  The CISTPL_DEVICE_A tuple describes regions in attribute
  memory.  The type flag indicates the type of memory device for this
  region.  The wp flag indicates if this region is write protected.  The
  speed field is in nanoseconds, and size is in bytes.  Address regions
  are assumed to be ordered consecutively starting with address 0.  The
  following device types are defined:

     CISTPL_DTYPE_NULL
        Specifies that there is no device, or a ``hole'' in the card
        address space.

     CISTPL_DTYPE_ROM
        Masked ROM
     CISTPL_DTYPE_OTPROM
        One-type programmable ROM.

     CISTPL_DTYPE_EPROM
        UV erasable PROM.

     CISTPL_DTYPE_EEPROM
        Electrically erasable PROM.

     CISTPL_DTYPE_FLASH
        Flash EPROM.

     CISTPL_DTYPE_SRAM
        Static or non-volatile RAM.

     CISTPL_DTYPE_DRAM
        Dynamic or volatile RAM.

     CISTPL_DTYPE_FUNCSPEC
        Specifies a function-specific device, such as a memory-mapped IO
        device or buffer, as opposed to general purpose storage.

     CISTPL_DTYPE_EXTEND
        Specifies an extended device type.  This type is reserved for
        future use.

  4.1.5.  CISTPL_VERS_1

  The cistpl_vers_1_t structure is given by:

       typedef struct cistpl_vers_1_t {
               u_char          major;
               u_char          minor;
               int             ns;
               int             ofs[CISTPL_VERS_1_MAX_PROD_STRINGS];
               char            str[254];
       } cistpl_vers_1_t;

  The ns field specifies the number of product information strings in
  the tuple.  The string data is contained in the str array.  Each
  string is null terminated, and ofs gives the offset to the start of
  each string.

  4.1.6.  CISTPL_ALTSTR

  The cistpl_altstr_t structure is given by:

       typedef struct cistpl_altstr_t {
               int             ns;
               int             ofs[CISTPL_ALTSTR_MAX_STRINGS];
               char            str[254];
       } cistpl_altstr_t;

  The ns field specifies the number of alternate language strings in the
  tuple.  The string data is contained in the str array.  Each string is
  null terminated, and ofs gives the offset to the start of each string.

  4.1.7.  CISTPL_JEDEC_C, CISTPL_JEDEC_A

  The cistpl_jedec_t structure is given by:

       typedef struct cistpl_jedec_t {
               int             nid;
               struct {
                       u_char  mfr;
                       u_char  info;
               } id[CISTPL_MAX_DEVICES];
       } cistpl_jedec_t;

  JEDEC identifiers describe the specific device type used to implement
  a region of card memory.  The nid field specifies the number of JEDEC
  identifiers in the tuple.  There should be a one-to-one correspondence
  between JEDEC identifiers and device descriptions in the corresponding
  CISTPL_DEVICE tuple.

  4.1.8.  CISTPL_CONFIG, CISTPL_CONFIG_CB

  The cistpl_config_t structure is given by:

       typedef struct cistpl_config_t {
               u_char          last_idx;
               u_int           base;
               u_int           rmask[4];
               u_char          subtuples;
       } cistpl_config_t;

  The last_idx field gives the index of the highest numbered
  configuration table entry.  The base field gives the offset of a
  card's configuration registers in attribute memory.  The rmask array
  is a series of bit masks indicating which configuration registers are
  present.  Bit 0 of rmask[0] is for the COR, bit 1 is for the CCSR, and
  so on.  The subtuples field gives the number of bytes of subtuples
  following the normal tuple contents.

  For CISTPL_CONFIG_CB, rmask is undefined, and base points to the
  CardBus status registers.

  4.1.9.  CISTPL_BAR

  The cistpl_bar_t structure is given by:

  typedef struct cistpl_bar_t {
          u_char          attr;
          u_int           size;
  } cistpl_long_t;

  A CISTPL_BAR tuple describes the characteristics of an address space
  region pointed to by a PCI base address register, for CardBus cards.

  The following bit fields are defined in attr:

     CISTPL_BAR_SPACE
        Identifies the base address register, from 1 to 6.  A value of 7
        describes the card's Extension ROM space.

     CISTPL_BAR_SPACE_IO
        If set, this address register maps IO space (as opposed to
        memory space).

     CISTPL_BAR_PREFETCH
        If set, this region can be prefetched.  controller.

     CISTPL_BAR_CACHEABLE
        If set, this region is cacheable as well as prefetchable.

     CISTPL_BAR_1MEG_MAP
        If set, this region should only be mapped into the first 1MB of
        the host's physical address space.

  4.1.10.  CISTPL_CFTABLE_ENTRY

  The cistpl_cftable_entry_t structure is given by:

       typedef struct cistpl_cftable_entry_t {
               u_char          index;
               u_char          flags;
               u_char          interface;
               cistpl_power_t  vcc, vpp1, vpp2;
               cistpl_timing_t timing;
               cistpl_io_t     io;
               cistpl_irq_t    irq;
               cistpl_mem_t    mem;
               u_char          subtuples;
       } cistpl_cftable_entry_t;

  A CISTPL_CFTABLE_ENTRY structure describes a complete operating mode
  for a card.  Many sections are optional.  The index field gives the
  configuration index for this operating mode; writing this value to the
  card's Configuration Option Register selects this mode.  The following
  fields are defined in flags:

     CISTPL_CFTABLE_DEFAULT
        Specifies that this is the default configuration table entry.

     CISTPL_CFTABLE_BVDS
        Specifies that this configuration implements the BVD1 and BVD2
        signals in the Pin Replacement Register.

     CISTPL_CFTABLE_WP
        Specifies that this configuration implements the write protect
        signal in the Pin Replacement Register.

     CISTPL_CFTABLE_RDYBSY
        Specifies that this configuration implements the Ready/Busy
        signal in the Pin Replacement Register.

     CISTPL_CFTABLE_MWAIT
        Specifies that the WAIT signal should be observed during memory
        access cycles.

     CISTPL_CFTABLE_AUDIO
        Specifies that this configuration generates an audio signal that
        can be routed to the host system speaker.

     CISTPL_CFTABLE_READONLY
        Specifies that the card has a memory region that is read-only in
        this configuration.

     CISTPL_CFTABLE_PWRDOWN
        Specifies that this configuration supports a power down mode,
        via the Card Configuration and Status Register.

  The cistpl_power_t structure is given by:

       typedef struct cistpl_power_t {
               u_char          present;
               u_char          flags;
               u_int           param[7];
       } cistpl_power_t;

  The present field is bit mapped and indicates which parameters are
  present for this power signal.  The following indices are defined:

     CISTPL_POWER_VNOM
        The nominal supply voltage.

     CISTPL_POWER_VMIN
        The minimum supply voltage.

     CISTPL_POWER_VMAX
        The maximum supply voltage.

     CISTPL_POWER_ISTATIC
        The continuous supply current required.

     CISTPL_POWER_IAVG
        The maximum current averaged over one second.

     CISTPL_POWER_IPEAK
        The maximum current averaged over 10 ms.

     CISTPL_POWER_IDOWN
        The current required in power down mode.

  Voltages are given in units of 10 microvolts.  Currents are given in
  units of 100 nanoamperes.

  The cistpl_timing_t structure is given by:

       typedef cistpl_timing_t {
               u_int           wait, waitscale;
               u_int           ready, rdyscale;
               u_int           reserved, rsvscale;
       } cistpl_timing_t;

  Each time consists of a base time in nanoseconds, and a scale
  multiplier.  Unspecified times have values of 0.

  The cistpl_io_t structure is given by:

       typedef struct cistpl_io_t {
               u_char          flags;
               int             nwin;
               struct {
                       u_int           base;
                       u_int           len;
               } win[CISTPL_IO_MAX_WIN;
       } cistpl_io_t;

  The number of IO windows is given by nwin.  Each window is described
  by a base address, base, and a length in bytes, len.  The following
  bit fields are defined in flags:

     CISTPL_IO_LINES_MASK
        The number of IO lines decoded by this card.

     CISTPL_IO_8BIT
        Indicates that the card supports split 8-bit accesses to 16-bit
        IO registers.

     CISTPL_IO_16BIT
        Indicates that the card supports full 16-bit accesses to IO
        registers.

  The cistpl_irq_t structure is given by:

       typedef struct cistpl_irq_t {
               u_int           IRQInfo1;
               u_int           IRQInfo2;
       } cistpl_irq_t;

  The following bit fields are defined in IRQInfo1:

     IRQ_MASK
        A specific interrupt number that this card should use.

     IRQ_NMI_ID, IRQ_IOCK_ID, IRQ_BERR_ID,
        IRQ_VEND_ID" When IRQ_INFO2_VALID is set, these indicate if a
        corresponding special interrupt signal may be assigned to this
        card.  The four flags are for the non-maskable, IO check, bus
        error, and vendor specific interrupts.

     IRQ_INFO2_VALID
        Indicates that IRQInfo2 contains a valid bit mask of allowed
        interrupt request numbers.

     IRQ_LEVEL_ID
        Indicates that the card supports level mode interrupts.

     IRQ_PULSE_ID
        Indicates that the card supports pulse mode interrupts.

     IRQ_SHARE_ID
        Indicates that the card supports sharing interrupts.

  If IRQInfo1 is 0, then no interrupt information is available.

  The cistpl_mem_t structure is given by:

       typedef struct cistpl_mem_t {
               u_char          nwin;
               struct {
                       u_int           len;
                       u_int           card_addr;
                       u_int           host_addr;
               } win[CISTPL_MEM_MAX_WIN;
       } cistpl_mem_t;

  The number of memory windows is given by nwin.  Each window is
  described by an address in the card memory space, card_addr, an
  address in the host memory space, host_addr, and a length in bytes,
  len.  If the host address is 0, the position of the window is
  arbitrary.

  4.1.11.  CISTPL_CFTABLE_ENTRY_CB

  The cistpl_cftable_entry_cb_t structure is given by:

       typedef struct cistpl_cftable_entry_cb_t {
               u_char          index;
               u_char          flags;
               cistpl_power_t  vcc, vpp1, vpp2;
               u_char          io;
               cistpl_irq_t    irq;
               u_char          mem;
               u_char          subtuples;
       } cistpl_cftable_entry_cb_t;

  A CISTPL_CFTABLE_ENTRY_CB structure describes a complete operating
  mode for a CardBus card.  Many fields are identical to corresponding
  fields in CISTPL_CFTABLE_ENTRY.

  The io and mem fields specify which base address registers need to be
  initialized for this configuration.  Bits 1 through 6 correspond to
  the six base address registers, and bit 7 indicates the expansion ROM
  base register.

  4.1.12.  CISTPL_MANFID

  The cistpl_manfid_t structure is given by:

       typedef struct cistpl_manfid_t {
               u_short         manf;
               u_short         card;
       } cistpl_manfid_t;

  The manf field identifies the card manufacturer.  The card field is
  chosen by the vendor and should identify the card type and model.

  4.1.13.  CISTPL_FUNCID

  The cistpl_funcid_t structure is given by:

       typedef struct cistpl_funcid_t {
               u_char          func;
               u_char          sysinit;
       } cistpl_funcid_t;

  The func field identifies the card function.  The sysinit field
  contains several bit-mapped flags describing how the card should be
  configured at boot time.

  The following functions are defined:

     CISTPL_FUNCID_MULTI
        A multi-function card.

     CISTPL_FUNCID_MEMORY
        A simple memory device.

     CISTPL_FUNCID_SERIAL
        A serial port or modem device.

     CISTPL_FUNCID_PARALLEL
        A parallel port device.

     CISTPL_FUNCID_FIXED
        A fixed disk device.

     CISTPL_FUNCID_VIDEO
        A video interface.

     CISTPL_FUNCID_NETWORK
        A network adapter.

     CISTPL_FUNCID_AIMS
        An auto-incrementing mass storage device.

  The following flags are defined in sysinit:

     CISTPL_SYSINIT_POST
        Indicates that the system should attempt to configure this card
        during its power-on initialization.

     CISTPL_SYSINIT_ROM
        Indicates that the card contains a system expansion ROM that
        should be configured at boot time.

  4.1.14.  CISTPL_DEVICE_GEO

  The cistpl_device_geo_t structure is given by:

       typedef struct cistpl_device_geo_t {
               int             ngeo;
               struct {
                       u_char          buswidth;
                       u_int           erase_block;
                       u_int           read_block;
                       u_int           write_block;
                       u_int           partition;
                       u_int           interleave;
               } geo[CISTPL_MAX_DEVICES];
       } cistpl_device_geo_t;

  The erase_block, read_block, and write_block sizes are in units of
  buswidth bytes times interleave.  The partition size is in units of
  erase_block.

  4.1.15.  CISTPL_VERS_2

  The cistpl_vers_2_t structure is given by:

       typedef struct cistpl_vers_2_t {
               u_char          vers;
               u_char          comply;
               u_short         dindex;
               u_char          vspec8, vspec9;
               u_char          nhdr;
               int             vendor, info;
               char            str[244];
       } cistpl_vers_2_t;

  The vers field should always be 0.  The comply field indicates the
  degree of standard compliance and should also be 0.  The dindex field
  reserves the specified number of bytes at the start of common memory.
  The vspec8 and vspec9 fields may contain vendor-specific information.
  The nhdr field gives the number of copies of the CIS that are present
  on this card.  The str array contains two strings: a vendor name, and
  an informational message describing the card.  The offset of the
  vendor string is given by vendor, and the offset of the product info
  string is in info.

  4.1.16.  CISTPL_ORG

  The cistpl_org_t structure is given by:

       typedef struct cistpl_org_t {
               u_char          data_org;
               char            desc[30];

  This tuple describes the data organization of a memory partition.  The
  following values are defined for data_org:

     CISTPL_ORG_FS
        The partition contains a filesystem.

     CISTPL_ORG_APPSPEC
        The partition is in an application specific format.

     CISTPL_ORG_XIP
        The partition follows the Execute-In-Place specification.

  The desc field gives a text description of the data organization.

  4.1.17.  CISTPL_FORMAT

  The cistpl_format_t structure is given by:

       typedef struct cistpl_org_t {
               u_char          type;
               u_char          edc;
               u_int           offset;
               u_int           length;

  This tuple describes the data recording format for a memory region.
  The following values are defined for type:

     CISTPL_FORMAT_DISK
        The partition uses a disk-like format.

     CISTPL_FORMAT_MEM
        The partition uses a memory-like format.

  The following values are defined for edc:

     CISTPL_EDC_NONE
        No error detection code is used.

     CISTPL_EDC_CKSUM
        Each block has a one-byte arithmetic checksum.

     CISTPL_EDC_CRC
        Each block has a two-byte cyclic redundancy check.

     CISTPL_EDC_PCC
        The entire partition has a one-byte checksum.

  The offset field specifies the address of the first data byte, and
  length specifies the total number of data bytes in this partition.

  4.2.  CIS configuration register definitions

  The PC Card standard defines a few standard configuration registers
  located in a card's attribute memory space.  A card's CONFIG tuple
  specifies which of these registers are implemented.  Programs using
  these definitions should include:

       #include "cisreg.h"

  4.2.1.  Configuration Option Register

  This register should be present for virtually all IO cards.  Writing
  to this register selects a configuration table entry and enables a
  card's IO functions.

  The following bit fields are defined:

     COR_CONFIG_MASK
        Specifies the configuration table index describing the card's
        current operating mode.

     COR_LEVEL_REQ
        Specifies that the card should generate level mode (edge-
        triggered) interrupts, the default.

     COR_SOFT_RESET
        Setting this bit performs a ``soft'' reset operation.  Drivers
        should use the ResetCard call to reset a card, rather than
        writing directly to this register.

  4.2.2.  Card Configuration and Status Register

  The following bit fields are defined:

     CCSR_INTR_ACK
        If this bit is set, then the CCSR_INTR_PENDING bit will remain
        set until it is explicitly cleared.
     CCSR_INTR_PENDING
        Signals that the card is currently asserting an interrupt
        request.  This signal may be helpful for supporting interrupt
        sharing.

     CCSR_POWER_DOWN
        Setting this bit signals that the card should enter a power down
        state.

     CCSR_AUDIO_ENA
        Specifies that the card's audio output should be enabled.

     CCSR_IOIS8
        This is used by the host to indicate that it can only perform
        8-bit IO operations and that 16-bit accesses will be carried out
        as two 8-bit accesses.

     CCSR_SIGCHG_ENA
        This indicates to the card that it should use the SIGCHG signal
        to indicate changes in the WP, READY, BVD1, and BVD2 signals.

     CCSR_CHANGED
        This bit signals to the host that one of the signals in the Pin
        Replacement Register has changed state.

  4.2.3.  Pin Replacement Register

  Signals in this register replace signals that are not available when a
  socket is operating in memory and IO mode.  An IO card will normally
  assert the SIGCHG signal to indicate that one of these signals has
  changed state, then a driver can poll this register to find out
  specifically what happened.

  The following bit fields are defined:

     PRR_WP_STATUS
        The current state of the write protect signal.

     PRR_READY_STATUS
        The current state of the ready signal.

     PRR_BVD2_STATUS
        The current state of the battery warn signal.

     PRR_BVD1_STATUS
        The current state of the battery dead signal.

     PRR_WP_EVENT
        Indicates that the write protect signal has changed state since
        the PRR register was last read.

     PRR_READY_EVENT
        Indicates that the ready signal has changed state since the PRR
        register was last read.

     PRR_BVD2_EVENT
        Indicates that the battery warn signal has changed state since
        the PRR register was last read.

     PRR_BVD1_EVENT
        Indicates that the battery dead signal has changed state since
        the PRR register was last read.

  This register can also be written.  In this case, the STATUS bits act
  as a mask; if a STATUS bit is set, the corresponding EVENT bit is
  updated by the write.

  4.2.4.  Socket and Copy Register

  This register is used when several identical cards may be set up to
  share the same range of IO ports, to emulate an ISA bus card that
  would control several devices.  For example, an ISA hard drive
  controller might control several drives, selectable by writing a drive
  number to an IO port.  For several card drives to emulate this
  controller interface, each needs to ``know'' which drive it is, so
  that it can identify which IO operations are intended for it.

  The following bit fields are defined:

     SCR_SOCKET_NUM
        This should indicate the socket number in which the card is
        located.

     SCR_COPY_NUM
        If several identical cards are installed in a system, this field
        should be set to a unique number identifying which of the
        identical cards this is.

  4.2.5.  Extended Status Register

  The following bit fields are defined:

     ESR_REQ_ATTN_ENA
        When set, the CCSR_CHANGED bit will be set when the ESR_REQ_ATTN
        bit is set, possibly generating a status change interrupt.

     ESR_REQ_ATTN
        Signals a card event, such as an incoming call for a modem.

  4.2.6.  IO Base and Size Registers

  For multifunction cards, these registers are used to tell the card how
  the host IO windows have been configured for each card function.
  There are four IO Base registers, from CISREG_IOBASE_0 to
  CISREG_IOBASE_3, for the low-order through high-order bytes of an IO
  address up to 32 bits long.  The CISREG_IOSIZE register is supposed to
  be written as the number of IO ports allocated, minus one.  For MFC-
  compliant cards, Card Services will automatically set all of these
  registers when RequestConfiguration is called.

  5.  Card Services Event Handling

  Card Services events have several sources:

  o  Card status changes reported by the low-level socket drivers.

  o  Artificial events generated by Card Services itself.

  o  Advanced Power Management (APM) events.

  o  Events generated by other Card Services clients.

  Socket driver events may be either interrupt-driven or polled.

  5.1.  Event handler operations

  When Card Services recognizes that an event has occurred, it checks
  the event mask of each client to determine which clients should
  receive an event notification.  When a client registers with Card
  Services, it specifies  an event handler callback function.  This
  handler should have the form:

       int (*event_handler)(event_t event, int priority, event_callback_args_t *args);

  The priority parameter is set to either CS_EVENT_PRI_LOW for ordinary
  events, or CS_EVENT_PRI_HIGH for events that require an immediate
  response.  The only high priority event is CS_EVENT_CARD_REMOVAL.  A
  client event handler should process this event as efficiently as
  possible so that Card Services can quickly notify other clients.

  The event_callback_args_t structure is given by:

       typedef struct event_callback_args_t {
               client_handle_t         client_handle;
               void                    *info;
               void                    *mtdrequest;
               void                    *buffer;
               void                    *misc;
               void                    *client_data;
               struct bus_operations   *bus;
       } event_callback_args_t;

  The client_handle member is set to the handle of the client whose
  socket was responsible for the event.  This is useful if a driver is
  bound to several sockets.  The info field is currently only used to
  return an exit status from a call to ResetCard.  The client_data field
  may be used by a driver to point to a local data structure associated
  with this device.  The remaining fields are currently unused.

  For sockets that do not directly map cards into the host IO and memory
  space, the bus field is a pointer to a table of entry points for IO
  primitives for this socket.

  5.2.  Event descriptions

     CS_EVENT_CARD_INSERTION
        This event signals that a card has been inserted.  If a driver
        is bound to an already occupied socket, Card Services will send
        the driver an artificial insertion event.

     CS_EVENT_CARD_REMOVAL
        This event signals that a card has been removed.  This event
        should be handled with minimum delay so that Card Services can
        notify all clients as quickly as possible.

     CS_EVENT_BATTERY_LOW
        This event signals a change of state of the ``battery low''
        signal.

     CS_EVENT_BATTERY_DEAD
        This event signals a change of state of the ``battery dead''
        signal.

     CS_EVENT_READY_CHANGE
        This event signals a change of state of the ``ready'' signal.

     CS_EVENT_WRITE_PROTECT
        This event signals a change of state of the ``write protect''
        signal.

     CS_EVENT_REGISTRATION_COMPLETE
        This event is sent to a driver after a successful call to
        RegisterClient.

     CS_EVENT_RESET_REQUEST
        This event is sent when a client calls ResetCard.  An event
        handler can veto the reset operation by returning failure.

     CS_EVENT_RESET_PHYSICAL
        This is sent to all clients just before a reset signal is sent
        to a card.

     CS_EVENT_CARD_RESET
        This event signals that a reset operation is finished.  The
        success or failure of the reset should be determined using
        GetStatus.

     CS_EVENT_RESET_COMPLETE
        This event is sent to a client that has called ResetCard to
        signal the end of reset processing.

     CS_EVENT_PM_SUSPEND
        This event signals that Card Services has received either a user
        initiated or APM suspend request.  An event handler can veto the
        suspend by returning failure.

     CS_EVENT_PM_RESUME
        This signals that the system is back on line after a
        suspend/resume cycle.

     CS_EVENT_MTD_REQUEST
        This is used to initiate an MTD memory operation.  A description
        of the request is passed in the mtdrequest field of the callback
        arguments.  A host buffer address may be passed in buffer.

     CS_EVENT_ERASE_COMPLETE
        This is used to signal a client that a queued erase operation
        has completed.  A pointer to the erase queue entry is returned
        in the info field of the callback arguments.

  5.3.  Client driver event handling responsibilities

  A client driver should respond to CS_EVENT_CARD_INSERTION and
  CS_EVENT_CARD_REMOVAL events by configuring and un-configuring the
  socket.  Because card removal is a high priority event, the driver
  should immediately block IO to the socket, perhaps by setting a flag
  in a device structure, and schedule all other shutdown processing to
  happen later using a timer interrupt.

  When a CS_EVENT_PM_RESET_REQUEST event is received, a driver should
  block IO and release a locked socket configuration.  When a
  CS_EVENT_CARD_RESET is received, a driver should restore the socket
  configuration and unblock IO.

  A CS_EVENT_PM_SUSPEND event should be handled somewhat like a
  CS_EVENT_PM_RESET_REQUEST event, in that IO should be blocked and the
  socket configuration should be released.  When a CS_EVENT_PM_RESUME
  event is received, a driver can expect a card to be ready to be
  reconfigured, similar to when a CS_EVENT_CARD_RESET event is received.

  6.  Memory Technology Drivers

  A Memory Technology Driver (``MTD'') is used by Card Services to
  implement bulk memory services for a particular type of memory device.
  An MTD should register as a normal Card Services client with a call to
  RegisterClient.  When it receives a card insertion event, it should
  use GetFirstRegion and GetNextRegion to identify memory regions that
  it will administer.  Then, it should use RegisterMTD to take control
  of these regions.  MTD read, write, copy, and erase requests are
  packaged into CS_EVENT_MTD_REQUEST events by Card Services, and passed
  to the MTD's event handler for processing.

  6.1.  MTD request handling

  An MTD receives requests from Card Services in the form of
  CS_EVENT_MTD_REQUEST events.  Card Services passes a description of
  the request in the mtdrequest field of the event callback arguments.
  For requests that transfer data to or from the host, the host buffer
  address is passed in the buffer field.

  The mtd_request_t structure is given by:

       typedef struct mtd_request_t {
               u_int           SrcCardOffset;
               u_int           DestCardOffset;
               u_int           TransferLength;
               u_int           Function;
               u_long          MediaID;
               u_int           Status;
               u_int           Timeout;
       } mtd_request_t;

  The Function field is bit mapped and describes the action to be
  performed by this request:

     MTD_REQ_ACTION
        Either MTD_REQ_ERASE, MTD_REQ_READ, MTD_REQ_WRITE, or
        MTD_REQ_COPY.
     MTD_REQ_NOERASE
        For a write command that is sized and aligned on erase block
        boundaries, this specifies that no erase should be performed.

     MTD_REQ_VERIFY
        Specifies that writes should be verified.

     MTD_REQ_READY
        Indicates that this request is a retry of a previously request
        that was delayed until the card asserted READY.

     MTD_REQ_TIMEOUT
        Indicates that this request is a retry of a previously request
        that was delayed by a timeout.

     MTD_REQ_FIRST
        Indicates that this request is the first in a series of
        requests.

     MTD_REQ_LAST
        Indicates that this request is the last of a series of requests.

     MTD_REQ_KERNEL
        Indicates that the host buffer for a read or write command is
        located in kernel memory, as opposed to user memory.

  The MediaID field is the value specified in the RegisterMTD request
  for this region.  The Status field is used by the MTD when it is
  unable to satisfy a request because a device is busy.  MTD requests
  normally run without blocking.  If an MTD request would block, it
  should return an error code of CS_BUSY, and set Status to one of the
  have the following values:

     MTD_WAITREQ
        Specifies that the request should be retried after another MTD
        request currently in progress completes.

     MTD_WAITTIMER
        Specifies that the request should be continued after the time
        specified in the timeout field.

     MTD_WAITRDY
        Specifies that the request should be continued when the card
        signals READY, or when the time specified in Timeout elapses,
        whichever happens first.

     MTD_WAITPOWER
        Specifies that the request should be retried after something
        happens that affects power availability to the socket.

  For MTD_WAITTIMER and MTD_WAITRDY, the Timeout field will specify the
  timeout interval in milliseconds.

  6.2.  MTD helper functions

  Since an MTD processes requests generated by Card Services, there may
  be some restrictions on the sorts of Card Services calls that can be
  safely made from the MTD event handler.  The MTD helper functions
  provide a limited set of special services that may be needed by an MTD
  but would be tricky to implement using the normal Card Services calls.
  In the Linux implementation, most CS calls can be safely made from an
  MTD event handler, but the MTD helper interface is included for
  compatibility.
       #include "cs_types.h"
       #include "cs.h"
       #include "bulkmem.h"

       int MTDHelperEntry(int subfunc, void *arg1, void *arg2);

  6.2.1.  MTDRequestWindow, MTDReleaseWindow

       int MTDHelperEntry(MTDRequestWindow, client_handle_t *handle, win_req_t *mod);
       int MTDHelperEntry(MTDReleaseWindow, window_handle_t handle);

  These services are identical to the standard Card Services
  RequestWindow and ReleaseWindow calls.

  6.2.2.  MTDModifyWindow

       int MTDHelperEntry(MTDModifyWindow, memory_handle_t handle, mtd_mod_req_t *mod);

  The mtd_mod_req_t structure is give by:

       typedef struct mtd_mod_req_t {
               u_int           Attributes;
               u_int           AccessSpeed;
               u_int           CardOffset;
       } mtd_mod_req_t;

  MTDModifyWindow is essentially equivalent to using the normal
  ModifyWindow and MapMemPage calls.

  The following flags can be specified in Attributes:

     WIN_MEMORY_TYPE
        Either WIN_MEMORY_TYPE_CM for common memory, or
        WIN_MEMORY_TYPE_AM for attribute memory.

     WIN_USE_WAIT
        Specifies that the controller should observe the card's MWAIT
        signal.

  A window configured with MTDModifyWindow will always be enabled, and
  have a 16 bit data width.

  Return codes:

     CS_BAD_HANDLE
        The memory handle is invalid.

  6.2.3.  MTDSetVpp

       int MTDHelperEntry(MTDSetVpp, client_handle_t client, mtd_vpp_req_t *req);

       typedef struct mtd_vpp_req_t {
               u_char          Vpp1, Vpp2;
       } mtd_vpp_req_t;

  MTDSetVpp changes the programming voltage for a socket.  Vpp1 and Vpp2
  should be given in units of 1/10 volt.  Currently, Vpp1 should always
  equal Vpp2.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

     CS_BAD_VPP
        The specified Vpp is not available, or Vpp1 does not equal Vpp2.

  6.2.4.  MTDRDYMask

       int MTDHelperEntry(MTDRDYMask, client_handle_t client, mtd_rdy_req_t *req);

       typedef struct mtd_rdy_req_t {
               u_int           Mask;
       } mtd_rdy_req_t;

  MTDRDYMask selects whether or not CS_EVENT_READY_CHANGE events will be
  enabled.  The client should already have indicated to Card Services
  that it should receive ready change events, via a call to either
  RegisterClient or SetEventMask.  Ready change events will be enabled
  if the CS_EVENT_READY_CHANGE bit is set in the Mask argument.

  Return codes:

     CS_BAD_HANDLE
        The client handle is invalid.

  7.  Driver Services Interface

  Driver Services provides a link between Card Services client drivers
  and user mode utilities like the cardmgr daemon.  It is a sort of Card
  Services ``super-client''.  Driver Services uses the BindDevice
  function to link other client drivers with their corresponding cards.
  Unlike other clients, Driver Services remains permanently bound to all
  sockets as cards are inserted and removed.

  7.1.  Interface to other client drivers

  Driver Services keeps track of all client drivers that are installed
  and ready to attach to a socket.  Client drivers need to have entry
  points for creating and deleting device ``instances'', where one
  device instance is everything needed to manage one physical card.

  Each client driver is identified by a unique 16-character tag that has
  the special type dev_info_t, defined in cs_types.h.  Each device
  instance is described by a dev_link_t structure.

  7.1.1.  The dev_link_t structure

  The dev_node_t and dev_link_t data structures are given by:

       #include "ds.h"

       typedef struct dev_node_t {
               char                    dev_name[DEV_NAME_LEN];
               u_char                  major, minor;
               struct dev_node_t       *next;
       }

       typedef struct dev_link_t {
               dev_node_t              *dev;
               u_int                   state, open;
               struct wait_queue       *pending
               struct timer_list       release
               client_handle_t         handle;
               io_req_t                io;
               irq_req_t               irq;
               config_req_t            conf;
               window_handle_t         win;
               void                    *priv;
               struct dev_link_t       *next;
       } dev_link_t;

  The dev field of the dev_link_t structure points to a linked list of
  dev_node_t structures.  In dev_node_t, the dev_name field should be
  filled in by the driver with a device file name for accessing this
  device, if appropriate.  For example, the serial_cs driver uses names
  like ``ttyS1''.  The major and minor fields give major and minor
  device numbers for accessing this device.  Driver Services relays
  these fields to user mode programs via the DS_GET_DEVICE_INFO ioctl.

  In dev_link_t, the state field should be used to keep track of the
  current device state.  The following flags are defined:

     DEV_PRESENT
        Indicates that the card is present.  This bit should be set and
        cleared by the driver's event handler in response to card
        insertion and removal events.

     DEV_CONFIG
        Indicates that the card is configured for use.

     DEV_CONFIG_PENDING
        Indicates that configuration is in progress.

     DEV_SUSPEND
        Indicates that the card is suspended.

     DEV_BUSY
        Indicates that an IO operation is in progress.  This bit may be
        used as an interlock to prevent access conflicts.

     DEV_STALE_CONFIG
        For some drivers, when a running card is ejected, the socket
        should not be unconfigured until any devices corresponding to
        this card are closed.  This flag indicates that the socket
        should be unconfigured when the device is closed.

     DEV_STALE_LINK
        A driver instance should not be deleted until all its resources
        are released.  This flag indicates that this driver instance
        should be freed as soon as the socket is unconfigured.

  The open field is a usage count for this device.  The device should
  only be freed when the open count is zero.  The pending field can be
  used to manage a queue of processes waiting to use the device.

  The release field is used to schedule device shutdown processing when
  a card is ejected.  A card removal event needs to be handled at high
  priority, so a driver's event handler will typically deal with an
  eject by resetting the DEV_PRESENT bit in the device state, then
  scheduling the shutdown processing to run at a later time.

  The handle, io, irq, conf, and win fields comprise all the normal data
  structures needed to configure an ordinary PC Card IO device

  The priv field can be used for any sort of private data structure
  needed to manage the device.  The next field can be used to build
  linked lists of dev_link_t structures, for drivers that can handle
  multiple instances.

  7.1.2.  register_pccard_driver

       int register_pccard_driver(dev_info_t *dev_info,
                                  dev_link_t *(*attach)(void),
                                  void (*detach)(dev_link_t *));

  register_pccard_driver informs Driver Services that a client driver is
  present and ready to be bound to sockets.  When Driver Services
  receives a DS_BIND_REQUEST ioctl that matches this driver's dev_info
  string, it will call the driver's attach() entry point.  When it gets
  a DS_UNBIND_REQUEST ioctl, it will call detach().

  7.1.3.  unregister_pccard_driver

       int unregister_pccard_driver(dev_info_t *dev_info);

  This informs Driver Services that it should no longer bind sockets to
  the specified client driver.

  7.2.  The CardBus client interface

  The CardBus card interface is designed to be essentially an extension
  of the PCI bus.  CardBus cards are typically designed using standard
  PCI chip sets.  For simplicity in the client drivers, and maximum code
  sharing with regular kernel PCI drivers, we provide a sort of ``super
  client'' for configuring CardBus cards.  This is implemented in the
  cb_enabler module.

  The cb_enabler module is somewhat similar in philosophy to the Driver
  Services layer for 16-bit cards.  CardBus client drivers register with
  it, and provide a few entry points for handling device setup and
  shutdown, as well as power management handling.  The cb_enabler module
  takes care of configuring the card and fielding Card Services events.
  So, all CardBus-specific code is in the enabler rather than the PCI
  driver.

  It is not mandatory for CardBus clients to use the cb_enabler
  interface.  If a particular client requires more direct control over
  its CardBus configuration than is provided through the cb_enabler
  module, it can register directly with Card Services and perform Card
  Services calls directly, just like a 16-bit client.

  The cb_enabler module has two entry points: register_driver and
  unregister_driver.  At some point, these functions may migrate into
  the kernel: hence the generic names.

  7.2.1.  register_driver

       int register_driver(struct driver_operations *ops);

  The driver_operations structure is given by:

       typedef struct driver_operations {
               char            *name
               dev_node_t      *(*attach) (dev_locator_t *loc);
               void            (*suspend) (dev_node_t *dev);
               void            (*resume) (dev_node_t *dev);
               void            (*detach) (dev_node_t *dev);
       } driver_operations;

  The name field is used by cb_enabler when registering this client with
  Card Services.  The rest of the structure describes a set of event
  handlers for this client.

  The function returns 0 on success, and -1 on failure.

  7.2.2.  unregister_driver

       void unregister_driver(struct driver_operations *ops);

  The ops parameter should be the same structure pointer passed to a
  prior successful call to register_driver.  The client should take care
  to only call this function when no devices are currently being managed
  by this client.

  7.2.3.  The driver_operations entry points

  The attach() entry point is used to configure a single device, given a
  ``device locator'' structure describing where to find it.

  The dev_locator_t structure is given by:

       typedef struct dev_locator_t {
               enum { LOC_ISA, LOC_PCI } bus;
               union {
                       struct {
                               u_short         io_base_1, io_base_2;
                               u_long          mem_base;
                               u_char          irq, dma;
                       } isa;
                       struct {
                               u_char          bus;
                               u_char          devfn;
                       } pci;
               } b;
       } dev_locator_t;

  The attach() function should return either NULL or a valid dev_node_t
  structure describing the new device.  All the other entry points will
  use this pointer to identify the device to be manipulated.  The
  cb_enabler module will invoke the attach() and detach() entry points
  in response to card insertion and removal events.  The suspend() and
  resume() entry points will be called in response to power management
  events.

  There is no way for a driver to refuse a suspend() or detach() event.
  When a detach() event is received, the driver should block any
  subsequent IO to the specified device, but may preserve internal data
  structures until the kernel device is actually closed.

  7.3.  Interface to user mode utilities

  Driver Services creates a pseudo-device for communicating with user
  mode PC Card utilities.  The major number of the device is chosen
  dynamically, and PC Card utilities should read /proc/devices to
  determine it.  Minor device numbers correspond to socket numbers,
  starting with 0.

  Only one process is allowed to open a socket for read/write access.
  Other processes can open the socket in read-only mode.  A read-only
  connection to Driver Services can perform a subset of ioctl calls.  A
  read/write connection can issue all ioctl calls, and can also receive
  Card Services event notifications.

  7.3.1.  Card Services event notifications

  Driver Services implements read() and select() functions for event
  notification.  Reading from a PC Card device returns an unsigned long
  value containing all the events received by Driver Services since the
  previous read().  If no events have been received, the call will block
  until the next event.  A select() call can be used to monitor several
  sockets for new events.

  The following events are monitored by Driver Services:
  CS_EVENT_CARD_INSERTION, CS_EVENT_CARD_REMOVAL,
  CS_EVENT_RESET_PHYSICAL, CS_EVENT_CARD_RESET, and
  CS_EVENT_RESET_COMPLETE.

  7.3.2.  Ioctl descriptions

  Most Driver Services ioctl operations directly map to Card Services
  functions.  An ioctl call has the form:

       int ioctl(int fd, int cmd, ds_ioctl_arg_t *arg);

  The ds_ioctl_arg_t structure is given by:

       typedef union ds_ioctl_arg_t {
               servinfo_t      servinfo;
               adjust_t        adjust;
               config_info_t   config;
               tuple_t         tuple;
               tuple_parse_t   tuple_parse;
               client_req_t    client_req;
               status_t        status;
               conf_reg_t      conf_reg;
               cisinfo_t       cisinfo;
               region_info_t   region;
               bind_info_t     bind_info;
               mtd_info_t      mtd_info;
               cisdump_t       cisdump;
       } ds_ioctl_arg_t;

  The following ioctl commands execute the corresponding Card Services
  function:

     DS_GET_CARD_SERVICES_INFO
        Calls CardServices(GetCardServicesInfo, ..., &arg->servinfo).

     DS_ADJUST_RESOURCE_INFO
        Calls CardServices(AdjustResourceInfo, ..., &arg->adjust).

     DS_GET_CONFIGURATION_INFO
        Calls CardServices(GetConfigurationInfo, ..., &arg->config).

     DS_GET_FIRST_TUPLE
        Calls CardServices(GetFirstTuple, ..., &arg->tuple).

     DS_GET_NEXT_TUPLE
        Calls CardServices(GetNextTuple, ..., &arg->tuple).

     DS_GET_TUPLE_DATA
        Calls CardServices(GetTupleData, ..., &arg->tuple_parse.tuple).
        The tuple data is returned in arg->tuple_parse.data.

     DS_PARSE_TUPLE
        Calls CardServices(ParseTuple, ..., &arg->tuple_parse.tuple,
        &arg->tuple_parse.parse).

     DS_RESET_CARD
        Calls CardServices(ResetCard, ...).

     DS_GET_STATUS
        Calls CardServices(GetStatus, ..., &arg->status).

     DS_ACCESS_CONFIGURATION_REGISTER
        Calls CardServices(AccessConfigurationRegister, ...,
        &arg->conf_reg).

     DS_VALIDATE_CIS
        Calls CardServices(ValidateCIS, ..., &arg->cisinfo).

     DS_SUSPEND_CARD
        Calls CardServices(SuspendCard, ...).

     DS_RESUME_CARD
        Calls CardServices(ResumeCard, ...).

     DS_EJECT_CARD
        Calls CardServices(EjectCard, ...).

     DS_INSERT_CARD
        Calls CardServices(InsertCard, ...).

     DS_GET_FIRST_REGION
        Calls CardServices(GetFirstRegion, ..., &arg->region).

     DS_GET_NEXT_REGION
        Calls CardServices(GetNextRegion, ..., &arg->region).

     DS_REPLACE_CIS
        Calls CardServices(ReplaceCIS, ..., &arg->cisdump).

  The following ioctl commands invoke special Driver Services functions.
  They act on bind_info_t structures:

  typedef struct bind_info_t {
          dev_info_t              dev_info;
          u_char                  function;
          struct dev_info_t       *instance;
          char                    name[DEV_NAME_LEN];
          u_char                  major, minor;
          void                    *next;
  } bind_info_t;

     DS_BIND_REQUEST
        This call connects a socket to a client driver.  The specified
        device ID dev_info is looked up in the list of registered
        drivers.  If this is a multifunction card, the function field
        identifies which card function is being bound.  If found, the
        driver is bound to this socket and function using the BindDevice
        call.  Then, Driver Services calls the client driver's attach()
        entry point to create a device instance.  The new dev_link_t
        pointer is returned in instance.

     DS_GET_DEVICE_INFO
        This call retrieves the dev_name, major, and minor entries from
        the dev_link_t structure pointed to by instance.

     DS_UNBIND_REQUEST
        This call calls the detach() function for the specified driver
        and instance, shutting down this device.

  Finally, the DS_BIND_MTD request takes an argument of type mtd_info_t:

       typedef struct mtd_info_t {
               dev_info_t      dev_info;
               u_int           Attributes;
               u_int           CardOffset;
       } mtd_info_t;

  This call associates an MTD identified by dev_info with a memory
  region described by Attributes and CardOffset, which have the same
  meanings as in the Card Services BindMTD call.

  8.  Anatomy of a Card Services Client Driver

  Each release of the Linux Card Services package comes with a well-
  commented ``dummy'' client driver that should be used as a starting
  point for writing a new driver.  Look for it in clients/dummy_cs.c.
  This is not just a piece of sample code: it is written to function as
  a sort of generic card enabler.  If bound to an IO card, it will read
  the card's CIS and configure the card appropriately, assuming that the
  card's CIS is complete and accurate.

  8.1.  Module initialization and cleanup

  All loadable modules must supply init_module() and cleanup_module()
  functions, which are invoked by the module support code when the
  module is installed and removed.  A client driver's init function
  should register the driver with Driver Services, via the
  register_pccard_driver() call.  The cleanup function should use
  unregister_pccard_driver() to unregister with Driver Services.
  Depending on the driver, the cleanup function may also need to free
  any device structures that still exist at shutdown time.

  8.2.  The *_attach() and *_detach() functions

  The *_attach() entry point is responsible for creating an ``instance''
  of the driver, setting up any data structures needed to manage one
  card.  The *_attach() function should allocate and initialize a
  dev_link_t structure, and call RegisterClient to establish a link with
  Card Services.  It returns a pointer to the new dev_link_t structure,
  or NULL if the new instance could not be created.

  The *_detach() entry point deletes a driver instance created by a
  previous call to *_attach.  It also breaks the link with Card
  Services, using DeregisterClient.

  The *_attach() entry point is called by Driver Services when a card
  has been successfully identified and mapped to a matching driver by a
  DS_BIND_REQUEST ioctl().  The *_detach() entry point is called in
  response to a DS_UNBIND_REQUEST ioctl() call.

  8.3.  The *_config() and *_release() functions

  The *_config() function is called to prepare a card for IO.  Most
  drivers read some configuration details from the card itsef, but most
  have at least some built-in knowledge of how the device should be set
  up.  For example, the serial card driver reads a card's CFTABLE_ENTRY
  tuples to determine appropriate IO port base addresses and
  corresponding configuration indices, but the driver ignores the
  interrupt information in the CIS.  The *_config function will parse
  relevant parts of a card's CIS, then make calls to RequestIO,
  RequestIRQ, and/or RequestWindow, then call RequestConfiguration.

  When a card is successfully configured, the *_config() routine should
  fill in the dev_name, major, and minor fields in the dev_link_t
  structure.  These fields will be returned to user programs by Driver
  Services in response to a DS_GET_DEVICE_INFO ioctl().

  The *_release() function should release any resource allocated by a
  previous call to *_config(), and blank out the device's dev_name
  field.

  The *_config() and *_release functions are normally called in response
  to card status change events or from timer interrupts.  Thus, they
  cannot sleep, and should not call other kernel functions that might
  block.

  8.4.  The client event handler

  The *_event() entry point is called from Card Services to notify a
  driver of card status change events.

  8.5.  Locking and synchronization issues

  A configured socket should only be released when all associated
  devices are closed.  Releasing a socket allows its system resources to
  be allocated for use by another device.  If the released resources are
  reallocated while IO to the original device is still in progress, the
  original driver may interfere with use of the new device.

  A driver instance should only be freed after its corresponding socket
  configuration has been released.  Card Services requires that a client
  explicitly release any allocated resources before a call to
  DeregisterClient will succeed.

  All loadable modules have a ``use count'' that is used by the system
  to determine when it is safe to unload a module.  The convention in
  client drivers is to increment the use count when a device is opened,
  and to decrement the count when a device is closed.  So, a driver can
  be unloaded whenever all associated devices are closed.  in
  particular, a driver can be unloaded even if it is still bound to a
  socket, and the module cleanup code needs to be able to appropriately
  free any such resources that are still allocated.  This should always
  be safe, because if the driver has a use count of zero, all devices
  are closed, which means all active sockets can be released, and all
  device instances can be detached.

  If a driver's *_release() function is called while a device is still
  open, it should set the DEV_STALE_CONFIG flag in the device state, to
  signal that the device should be released when the driver's close()
  function is called.  If *_detach() is called for a configured device,
  the DEV_STALE_LINK flag should be set to signal that the instance
  should be detached when the *_release() function is called.

  8.6.  Using existing Linux drivers to access PC Card devices

  Many of the current client drivers use existing Linux driver code to
  perform device IO operations.  The Card Services client module handles
  card configuration and responds to card status change events, but
  delegates device IO to a compatible driver for a conventional ISA bus
  card.  In some cases, a conventional driver can be used without
  modification.  However, to fully support PC Card features like hot
  swapping and power management, there needs to be some communication
  between the PC Card client code and the device IO code.

  Most Linux drivers expect to probe for devices at boot time, and are
  not designed to handle adding and removing devices.  One side-effect
  of the move towards driver modularization is that it is usually easier
  to adapt a modularized driver to handle removable devices.

  It is important that a device driver be able to recover from having a
  device disappear at an inappropriate time.  At best, the driver should
  check for device presence before attempting any IO operation or before
  handling an IO interrupt.  Loops that check device status should have
  timeouts so they will eventually exit if a device never responds.

  The dummy_cs driver may be useful for loading legacy drivers for
  compatible PC Card devices.  After binding dummy_cs to a card, the
  legacy driver module may be able to detect and communicate with the
  device as if it were not a PC Card.  This arrangement will generally
  not support clean hot swapping or power management functions, however
  it may be useful as a basis for later developing a more full-featured
  client driver.

  9.  The Socket Driver Layer

  In the Linux PCMCIA model, the ``Socket Services'' layer is a private
  API intended only for the use of Card Services.  The API is based
  loosely on the PCMCIA Socket Services specification, but is oriented
  towards support for the common x86 laptop host controller types.

  9.1.  Card Services entry points for socket drivers

  Card Services provides special entry points for registering and
  unregistering socket drivers:

       typedef int (*ss_entry_t)(u_int sock, u_int cmd, void *arg);
       extern int register_ss_entry(int nsock, ss_entry_t entry);
       extern void unregister_ss_entry(ss_entry_t entry);

  The socket driver invokes register_ss_entry with nsock indicating how
  many sockets are owned by this driver, and entry pointing to the
  function that will provide socket services for these sockets.  The
  unregister_ss_entry routine can be safely invoked whenever Card
  Services does not have any callback functions registered for sockets
  owned by this driver.

  9.2.  Services provided by the socket driver

  Socket Services calls have the following form:

       #include "pcmcia/ss.h"

       int (*ss_entry)(u_int sock, int service, void *arg);

  Non-zero return codes indicate that a request failed.

  9.2.1.  SS_InquireSocket

       int (*ss_entry)(u_int sock, SS_InquireSocket, socket_cap_t *cap);

  The socket_cap_t data structure is given by:

       typedef struct socket_cap_t {
               u_int           features;
               u_int           irq_mask;
               u_int           map_size;
               u_char          pci_irq;
               u_char          cardbus;
               struct bus_operations *bus;
       } socket_cap_t;

  The SS_InquireSocket service is used to retrieve socket capabilities.
  The irq_mask field is a bit mask indicating which ISA interrupts can
  be configured for IO cards.  The map_size field gives the address
  granularity of memory windows.  The pci_irq field, if not zero, is the
  PCI interrupt number assigned to this socket.  It is independent of
  irq_mask, and can actually be used in any situation where exactly one
  interrupt is associated with a specific socket.  For CardBus bridges,
  the cardbus field should be non-zero, and gives the PCI bus number of
  the CardBus side of the bridge.

  For sockets that do not directly map cards into the host IO and memory
  space, the bus field is a pointer to a table of entry points for IO
  primitives for this socket.

  The following flags may be specified in features:

     SS_CAP_PAGE_REGS
        Indicates that this socket supports full 32-bit addressing for
        16-bit PC Card memory windows.

     SS_CAP_VIRTUAL_BUS
        Indicates that 16-bit card memory and IO accesses must be
        performed using the bus operations table, rather than using
        native bus operations.

     SS_CAP_MEM_ALIGN
        Indicates that memory windows must be aligned by the window
        size.

     SS_CAP_STATIC_MAP
        Indicates that memory windows are statically mapped at fixed
        locations in the host address space, and cannot be repositioned.

     SS_CAP_PCCARD
        Indicates that this socket supports 16-bit PC cards.

     SS_CAP_CARDBUS
        Indicates that this socket supports 32-bit CardBus cards.

  9.2.2.  SS_RegisterCallback

       int (*ss_entry)(u_int sock, SS_RegisterCallback, ss_callback_t *call);

  The ss_callback_t data structure is given by:

       typedef struct ss_callback_t {
               void            (*handler)(void *info, u_int events);
               void            *info;
       } ss_callback_t;

  The SS_RegisterCallback service sets up a callback function to be
  invoked when the socket driver receives card status change events.  To
  unregister a callback, this function is called with a handler value of
  NULL.  Only one callback function can be registered per socket.
  The handler will be called with the value of info that was passed to
  SS_RegisterCallback for this socket, and with a bit map of events in
  the events parameter.  The following events are defined:

     SS_DETECT
        A card detect change (insertion or removal) has been detected.

     SS_READY
        A memory card's ready signal has changed state.

     SS_BATDEAD
        A memory card has raised the battery-dead signal.

     SS_BATWARN
        A memory card has raised the battery-low signal.

     SS_STSCHG
        An IO card has raised the status change signal.

  9.2.3.  SS_GetStatus

       int (*ss_entry)(u_int sock, SS_GetStatus, u_int *status);

  The SS_GetStatus service returns the current status of this socket.
  The status parameter will be constructed out of the following flags:

     SS_WRPROT
        The card is write-protected.

     SS_BATDEAD
        A memory card has raised the battery-dead signal.

     SS_BATWARN
        A memory card has raised the battery-low signal.

     SS_READY
        A memory card has raised its ready signal.

     SS_DETECT
        A card is present.

     SS_POWERON
        Power has been applied to the socket.

     SS_STSCHG
        An IO card has raised the status change signal.

     SS_CARDBUS
        The socket contains a CardBus card (as opposed to a 16-bit PC
        Card).

     SS_3VCARD
        The card must be operated at no more than 3.3V.

     SS_XVCARD
        The card must be operated at no more than X.XV (not yet
        defined).
  9.2.4.  SS_GetSocket, SS_SetSocket

       int (*ss_entry)(u_int sock, SS_GetSocket, socket_state_t *);
       int (*ss_entry)(u_int sock, SS_SetSocket, socket_state_t *);

  The socket_state_t data structure is given by:

       typedef struct socket_state_t {
               u_int           flags;
               u_int           csc_mask;
               u_char          Vcc, Vpp;
               u_char          io_irq;
       } socket_state_t;

  The csc_mask field indicates which event types should generate card
  status change interrupts.  The following event types can be monitored:

     SS_DETECT
        Card detect changes (insertion or removal).

     SS_READY
        Memory card ready/busy changes.

     SS_BATDEAD
        Memory card battery-dead changes.

     SS_BATWARN
        Memory card battery-low changes.

     SS_STSCHG
        IO card status changes.

  The Vcc and Vpp parameters are in units of 0.1 volts.  If non-zero,
  io_irq specifies an interrupt number to be assigned to the card, in IO
  mode.  The following fields are defined in flags:

     SS_PWR_AUTO
        Indicates that the socket should automatically power up sockets
        at card insertion time, if supported.

     SS_IOCARD
        Indicates that the socket should be configured for ``memory and
        IO'' interface mode, as opposed to simple memory card mode.

     SS_RESET
        Indicates that the card's hardware reset signal should be
        raised.

     SS_SPKR_ENA
        Indicates that speaker output should be enabled for this socket.

     SS_OUTPUT_ENA
        Indicates that data signals to the card should be activated.

  9.2.5.  SS_GetIOMap, SS_SetIOMap

       int (*ss_entry)(u_int sock, SS_GetIOMap, pccard_io_map *);
       int (*ss_entry)(u_int sock, SS_SetIOMap, pccard_io_map *);

  The pccard_io_map data structure is given by:

       typedef struct pccard_io_map {
               u_char          map;
               u_char          flags;
               u_short         speed;
               u_short         start, stop;
       } pccard_io_map;

  The SS_GetIOMap and SS_SetIOMap entries are used to configure IO space
  windows.  IO windows are assumed to not support address translation.
  The Linux Card Services layer assumes that each socket has at least
  two independently configurable IO port windows.

  The map field specifies which IO map should be accessed.  The speed
  field is the map access speed in nanoseconds.  The start and stop
  fields give the lower and upper addresses for the IO map.  The flags
  field is composed of the following:

     MAP_ACTIVE
        Specifies that the address map should be enabled.

     MAP_16BIT
        Specifies that the map should be configured for 16-bit accesses
        (as opposed to 8-bit).

     MAP_AUTOSZ
        Specifies that the map should be configured to auto-size bus
        accesses in response to the card's IOCS16 signal.

     MAP_0WS
        Requests zero wait states, as opposed to standard ISA bus
        timing.

     MAP_WRPROT
        Specifies that the map should be write protected.

     MAP_USE_WAIT
        Specifies that access timing should respect the card's WAIT
        signal.

     MAP_PREFETCH
        Specifies that this map may be configured for prefetching.

  9.2.6.  SS_GetMemMap, SS_SetMemMap

  int (*ss_entry)(u_int sock, SS_GetMemMap, pccard_mem_map *);
  int (*ss_entry)(u_int sock, SS_SetMemMap, pccard_mem_map *);

  The pccard_mem_map data structure is given by:

       typedef struct pccard_mem_map {
               u_char          map;
               u_char          flags;
               u_short         speed;
               u_long          sys_start, sys_stop;
               u_int           card_start;
       } pccard_mem_map;

  The map field specifies the map number.  The speed field specifies an
  access speed in nanoseconds.  The sys_start and sys_stop fields give
  the starting and ending addresses for the window in the host's
  physical address space.  The card_start value specifies the card
  address to be mapped to sys_start.  The Linux Card Services layer
  assumes that each socket has at least four independently configurable
  memory windows.

     MAP_ACTIVE
        Specifies that the address map should be enabled.

     MAP_16BIT
        Specifies that the map should be configured for 16-bit accesses
        (as opposed to 8-bit).

     MAP_AUTOSZ
        Specifies that the map should be configured to auto-size bus
        accesses in response to the card's IOCS16 signal.

     MAP_0WS
        Requests zero wait states, as opposed to standard ISA bus
        timing.

     MAP_WRPROT
        Specifies that the map should be write protected.

     MAP_ATTRIB
        Specifies that the map should be for attribute (as opposed to
        common) memory.

     MAP_USE_WAIT
        Specifies that access timing should respect the card's WAIT
        signal.

  9.2.7.  SS_GetBridge, SS_SetBridge

       int (*ss_entry)(u_int sock, SS_GetBridge, cb_bridge_map *);
       int (*ss_entry)(u_int sock, SS_SetBridge, cb_bridge_map *);

  The cb_bridge_map data structure is given by:

       typedef struct cb_bridge_map {
               u_char          map;
               u_char          flags;
               u_int           start, stop;
       } cb_bridge_map;

  The SS_GetBridge and SS_SetBridge entry points are used for
  configuring bridge address windows for CardBus devices.  They are
  similar to the 16-bit IO and memory map services.  It is assumed that
  each CardBus socket has at least two IO and two memory bridge windows.
  The flags field is composed of:

     MAP_ACTIVE
        Specifies that the address map should be enabled.

     MAP_PREFETCH
        Specifies that this map can be configured for prefetching.

     MAP_IOSPACE
        Specifies that this map should be for IO space (as opposed to
        memory space).

  9.2.8.  SS_ProcSetup

       int (*ss_entry)(u_int sock, SS_ProcSetup, struct proc_dir_entry *base);

  Card Services uses this entry point to give the socket driver a procfs
  directory handle under which it may create status files for a specific
  socket.  It is the socket driver's responsbility to delete any proc
  entries before it is unloaded.

  9.3.  Supporting unusual socket architectures

  The Socket Services interface is oriented towards socket controllers
  that allow PCMCIA cards to be configured to mimic native system
  devices with the same functionality.  The ExCA standard specifies that
  socket controllers should provide two IO and five memory windows per
  socket, which can be independently configured and positioned in the
  host address space and mapped to arbitrary segments of card address
  space.  Some controllers and architectures do not provide this level
  of functionality.  In these situations, Socket Services can
  effectively virtualize the socket interface for client drivers.

  On the client side (including internal Card Services uses), to use the
  virtualized socket interface, code must first specify:

       #include "pcmcia/bus_ops.h"

  All IO operations then need to be replaced with new bus-neutral forms.
  The following functions need to be virtualized:

  o  inb, inw, inl, inw_ns, inl_ns

  o  insb, insw, insl, insw_ns, insl_ns

  o  outb, outw, outl, outw_ns, outl_ns

  o  outsb, outsw, outsl, outsw_ns, outsl_ns

  o  readb, readw, readl, readw_ns, readl_ns

  o  writeb, writew, writel, writew_ns, writel_ns

  o  ioremap, iounmap

  o  memcpy_fromio, memcpy_toio

  o  request_irq, free_irq

  The bus-neutral functions have a prefix of ``bus_'', with a new first
  argument, the bus operations table pointer returned by
  SS_InquireSocket.  For example, inb(port) should be replaced with
  bus_inb(bus, port).

  All the IO primitives are defined as macros that call entry points in
  the bus operations table.  There is not a one-to-one mapping from IO
  primitives to bus operation entry points.

  The bus operations table is defined as:

       typedef struct bus_operations {
               void    *priv;
               u32     (*b_in)(void *bus, u32 port, s32 sz);
               void    (*b_ins)(void *bus, u32 port, void *buf,
                                u32 count, s32 sz);
               void    (*b_out)(void *bus, u32 val, u32 port, s32 sz);
               void    (*b_outs)(void *bus, u32 port, void *buf,
                                 u32 count, s32 sz);
               void    *(*b_ioremap)(void *bus, u_long ofs, u_long sz);
               void    (*b_iounmap)(void *bus, void *addr);
               u32     (*b_read)(void *bus, void *addr, s32 sz);
               void    (*b_write)(void *bus, u32 val, void *addr, s32 sz);
               void    (*b_copy_from)(void *bus, void *d, void *s, u32 count);
               void    (*b_copy_to)(void *bus, void *d, void *s, u32 count);
               int     (*b_request_irq)(void *bus, u_int irq,
                                        void (*handler)(int, void *,
                                                        struct pt_regs *),
                                        u_long flags, const char *device,
                                        void *dev_id);
               void    (*b_free_irq)(void *bus, u_int irq, void *dev_id);
       } bus_operations;

  The priv field can be used for any purpose by the socket driver, for
  instance, to indicate which of several sockets is being addressed.
  The b_in, b_out, b_read, and b_write entry points each support byte,
  word, and dword operations, either byte-swapped or unswapped.  The sz
  parameter is 0, 1, or 2 for byte, word, or dword accesses; -1 and -2
  select word and dword unswapped accesses.

  10.  Where to Go for More Information

  The Linux Kernel Hackers' Guide, written by Michael Johnson, is a good
  source of general information about writing Linux device drivers.  It
  is available from the usual Linux FTP sites, and is included in many
  compilations of Linux documentation.

  The PC Card standard is only available from the PCMCIA association
  itself, and is somewhat expensive for non-members.  The PCMCIA
  association is at  <http://www.pc-card.com>, or:

       Personal Computer Memory Card International Association
       1030 East Duane Avenue, Suite G
       Sunnyvale, CA 94086 USA
       (408) 720-0107, (408) 720-9416 FAX, (408) 720-9388 BBS

  An alternative is the PCMCIA Developer's Guide, by Michael Mori, ISBN
  0-9640342-1-2, available from Sycard Technology, at
  <http://www.sycard.com> or:

       Sycard Technology
       1180-F Miraloma Way
       Sunnyvale, CA 94086 USA
       (408) 749-0130, (408) 749-1323 FAX

  The PCMCIA Software Developer's Handbook by Steven Kipisz, Dana
  Beatty, and Brian Moore includes an overview of the PC Card standard,
  and descriptions of how to write client drivers.  It also includes the
  Linux PCMCIA Programmer's Guide, as an appendix.  It is published by
  Peer-to-Peer Communications, ISBN 1-57398-010-2.

  Larry Levine has written a more general introduction to PCMCIA called
  the PCMCIA Primer.  It is published by M & T Books, ISBN
  1-55828-437-0.

  Programming information for various PC Card host controllers is
  available from the corresponding chip vendors.  Generally, data sheets
  are either available on line or can be ordered from each company's web
  site.  A collection of datasheets can be found at <http:/pcmcia-
  cs.sourceforge.net/specs>.

