interface

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

$Id: INTERFACE,v 1.1.4.1 2001/11/20 14:19:33 kai Exp $

Description of the Interface between Linklevel and Hardwarelevel
  of isdn4linux:


  The Communication between Linklevel (LL) and Hardwarelevel (HL)
  is based on the struct isdn_if (defined in isdnif.h).

  An HL-driver can register itself at LL by calling the function
  register_isdn() with a pointer to that struct. Prior to that, it has
  to preset some of the fields of isdn_if. The LL sets the rest of
  the fields. All further communication is done via callbacks using
  the function-pointers defined in isdn_if.

  Changes/Version numbering:

  During development of the ISDN subsystem, several changes have been
  made to the interface. Before it went into kernel, the package
  had a unique version number. The last version, distributed separately
  was 0.7.4. When the subsystem went into kernel, every functional unit
  got a separate version number. These numbers are shown at initialization,
  separated by slashes:

     c.c/t.t/n.n/p.p/a.a/v.v

  where

   c.c is the revision of the common code.
   t.t is the revision of the tty related code.
   n.n is the revision of the network related code.
   p.p is the revision of the ppp related code.
   a.a is the revision of the audio related code.
   v.v is the revision of the V.110 related code.

  Changes in this document are marked with '***CHANGEx' where x representing
  the version number. If that number starts with 0, it refers to the old,
  separately distributed package. If it starts with one of the letters
  above, it refers to the revision of the corresponding module. 
  ***CHANGEIx refers to the revision number of the isdnif.h  

1. Description of the fields of isdn_if:

  int channels;

    This field has to be set by the HL-driver to the number of channels
    supported prior to calling register_isdn(). Upon return of the call,
    the LL puts an id there, which has to be used by the HL-driver when
    invoking the other callbacks.

  int maxbufsize;

    ***CHANGE0.6: New since this version.

    Also to be preset by the HL-driver. With this value the HL-driver
    tells the LL the maximum size of a data-packet it will accept. 

  unsigned long features;

    To be preset by the HL-driver. Using this field, the HL-driver
    announces the features supported. At the moment this is limited to
    report the supported layer2 and layer3-protocols. For setting this
    field the constants ISDN_FEATURE..., declared in isdnif.h have to be
    used.

    ***CHANGE0.7.1: The line type (1TR6, EDSS1) has to be set.

  unsigned short hl_hdrlen;

    ***CHANGE0.7.4: New field.

    To be preset by the HL-driver, if it supports sk_buff's. The driver
    should put here the amount of additional space needed in sk_buff's for
    its internal purposes. Drivers not supporting sk_buff's should 
    initialize this field to 0.

  void (*rcvcallb_skb)(int, int, struct sk_buff *)

    ***CHANGE0.7.4: New field.

    This field will be set by LL. The HL-driver delivers received data-
    packets by calling this function. Upon calling, the HL-driver must
    already have its private data pulled off the head of the sk_buff.

    Parameter:
      int              driver-Id
      int              Channel-number locally to the driver. (starting with 0)
      struct sk_buff * Pointer to sk_buff, containing received data.

  int (*statcallb)(isdn_ctrl*);

    This field will be set by LL. This function has to be called by the
    HL-driver for signaling status-changes or other events to the LL.

    Parameter:
      isdn_ctrl*

      The struct isdn_ctrl also defined in isdn_if. The exact meanings of its
      fields are described together with the descriptions of the possible
      events. Here is only a short description of the fields:

        driver  = driver Id.
        command = event-type. (one of the constants ISDN_STAT_...)
        arg     = depends on event-type.
        num     = depends on event-type.

    Returnvalue:
      0 on success, else -1

  int (*command)(isdn_ctrl*);

    This field has to be preset by the HL-driver. It points to a function,
    to be called by LL to perform functions like dialing, B-channel
    setup, etc. The exact meaning of the parameters is described with the
    descriptions of the possible commands.

    Parameter:
      isdn_ctrl*
        driver  = driver-Id
        command = command to perform. (one of the constants ISDN_CMD_...)
        arg     = depends on command.
        num     = depends on command.
    
    Returnvalue:
      >=0 on success, else error-code (-ENODEV etc.)

  int (*writebuf_skb)(int, int, int, struct sk_buff *)

    ***CHANGE0.7.4: New field.
    ***CHANGEI.1.21: New field.

    This field has to be preset by the HL-driver. The given function will
    be called by the LL for delivering data to be send via B-Channel.

 
    Parameter:
      int              driver-Id ***CHANGE0.7.4: New parameter.
      int              channel-number locally to the HL-driver. (starts with 0)
      int	       ack ***ChangeI1.21: New parameter
		       If this is !0, the driver has to signal the delivery
		       by sending an ISDN_STAT_BSENT. If this is 0, the driver
		       MUST NOT send an ISDN_STAT_BSENT.
      struct sk_buff * Pointer to sk_buff containing data to be send via
                       B-channel.

    Returnvalue:
      Length of data accepted on success, else error-code (-EINVAL on
      oversized packets etc.)

  int (*writecmd)(u_char*, int, int, int, int);

    This field has to be preset by the HL-driver. The given function will be
    called to perform write-requests on /dev/isdnctrl (i.e. sending commands
    to the card) The data-format is hardware-specific. This function is
    intended for debugging only. It is not necessary for normal operation
    and never will be called by the tty-emulation- or network-code. If
    this function is not supported, the driver has to set NULL here.

    Parameter:
      u_char* pointer to data.
      int     length of data.
      int     flag: 0 = call from within kernel-space. (HL-driver must use
                        memcpy, may NOT use schedule())
                    1 = call from user-space. (HL-driver must use
                        memcpy_fromfs, use of schedule() allowed)
      int     driver-Id.
      int     channel-number locally to the HL-driver. (starts with 0)

***CHANGEI1.14: The driver-Id and channel-number are new since this revision.

    Returnvalue:
      Length of data accepted on success, else error-code (-EINVAL etc.)

  int (*readstat)(u_char*, int, int, int, int);

    This field has to be preset by the HL-driver. The given function will be
    called to perform read-requests on /dev/isdnctrl (i.e. reading replies
    from the card) The data-format is hardware-specific. This function is
    intended for debugging only. It is not necessary for normal operation
    and never will be called by the tty-emulation- or network-code. If
    this function is not supported, the driver has to set NULL here.

    Parameter:
      u_char* pointer to data.
      int     length of data.
      int     flag: 0 = call from within kernel-space. (HL-driver must use
                        memcpy, may NOT use schedule())
                    1 = call from user-space. (HL-driver must use
                        memcpy_fromfs, use of schedule() allowed)
      int     driver-Id.
      int     channel-number locally to the HL-driver. (starts with 0)

***CHANGEI1.14: The driver-Id and channel-number are new since this revision.

    Returnvalue:
      Length of data on success, else error-code (-EINVAL etc.)

  char id[20];
       ***CHANGE0.7: New since this version.

   This string has to be preset by the HL-driver. Its purpose is for
   identification of the driver by the user. Eg.: it is shown in the
   status-info of /dev/isdninfo. Furthermore it is used as Id for binding
   net-interfaces to a specific channel. If a string of length zero is
   given, upon return, isdn4linux will replace it by a generic name. (line0,
   line1 etc.) It is recommended to make this string configurable during
   module-load-time. (copy a global variable to this string.) For doing that,
   modules 1.2.8 or newer are necessary.

2. Description of the commands, a HL-driver has to support:

   All commands will be performed by calling the function command() described
   above from within the LL. The field command of the struct-parameter will
   contain the desired command, the field driver is always set to the
   appropriate driver-Id.

   Until now, the following commands are defined:

***CHANGEI1.34: The parameter "num" has been replaced by a union "parm" containing
                the old "num" and a new setup_type struct used for ISDN_CMD_DIAL
                and ISDN_STAT_ICALL callback.

   ISDN_CMD_IOCTL:

     This command is intended for performing ioctl-calls for configuring
     hardware or similar purposes (setting port-addresses, loading firmware
     etc.) For this purpose, in the LL all ioctl-calls with an argument
     >= IIOCDRVCTL (0x100) will be handed transparently to this
     function after subtracting 0x100 and placing the result in arg.
     Example:
       If a userlevel-program calls ioctl(0x101,...) the function gets
       called with the field command set to 1.

     Parameter:
       driver   = driver-Id.
       command  = ISDN_CMD_IOCTL
       arg      = Original ioctl-cmd - IIOCDRVCTL
       parm.num = first bytes filled with (unsigned long)arg
   
     Returnvalue:
       Depending on driver.

  
  ISDN_CMD_DIAL:

    This command is used to tell the HL-driver it should dial a given
    number.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_DIAL
      arg         = channel-number locally to the driver. (starting with 0)
      
      parm.setup.phone  = An ASCII-String containing the number to dial.
      parm.setup.eazmsn = An ASCII-Sting containing the own EAZ or MSN.
      parm.setup.si1    = The Service-Indicator.
      parm.setup.si2    = Additional Service-Indicator.

                    If the Line has been designed as SPV (a special german
                    feature, meaning semi-leased-line) the phone has to
                    start with an "S".
      ***CHANGE0.6: In previous versions the EAZ has been given in the
                    highbyte of arg.
    ***CHANGE0.7.1: New since this version: ServiceIndicator and AddInfo.

  ISDN_CMD_ACCEPTD:

    With this command, the HL-driver is told to accept a D-Channel-setup.
    (Response to an incoming call)

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_ACCEPTD
      arg         = channel-number locally to the driver. (starting with 0)
      parm        = unused.

  ISDN_CMD_ACCEPTB:

    With this command, the HL-driver is told to perform a B-Channel-setup.
    (after establishing D-Channel-Connection)

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_ACCEPTB
      arg         = channel-number locally to the driver. (starting with 0)
      parm        = unused.

  ISDN_CMD_HANGUP:

    With this command, the HL-driver is told to hangup (B-Channel if
    established first, then D-Channel). This command is also used for
    actively rejecting an incoming call.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_HANGUP
      arg         = channel-number locally to the driver. (starting with 0)
      parm        = unused.

  ISDN_CMD_CLREAZ:

    With this command, the HL-driver is told not to signal incoming
    calls to the LL.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_CLREAZ
      arg         = channel-number locally to the driver. (starting with 0)
      parm        = unused.

  ISDN_CMD_SETEAZ:

    With this command, the HL-driver is told to signal incoming calls for
    the given EAZs/MSNs to the LL.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_SETEAZ
      arg         = channel-number locally to the driver. (starting with 0)
      parm.num    = ASCII-String, containing the desired EAZ's/MSN's
                    (comma-separated). If an empty String is given, the
                    HL-driver should respond to ALL incoming calls,
                    regardless of the destination-address.
      ***CHANGE0.6: New since this version the "empty-string"-feature.

  ISDN_CMD_GETEAZ: (currently unused)

    With this command, the HL-driver is told to report the current setting
    given with ISDN_CMD_SETEAZ.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_GETEAZ
      arg         = channel-number locally to the driver. (starting with 0)
      parm.num    = ASCII-String, containing the current EAZ's/MSN's

  ISDN_CMD_SETSIL: (currently unused)

    With this command, the HL-driver is told to signal only incoming
    calls with the given Service-Indicators.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_SETSIL
      arg         = channel-number locally to the driver. (starting with 0)
      parm.num    = ASCII-String, containing the desired Service-Indicators.

  ISDN_CMD_GETSIL: (currently unused)

    With this command, the HL-driver is told to return the current
    Service-Indicators it will respond to.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_SETSIL
      arg         = channel-number locally to the driver. (starting with 0)
      parm.num    = ASCII-String, containing the current Service-Indicators.

  ISDN_CMD_SETL2:

    With this command, the HL-driver is told to select the given Layer-2-
    protocol. This command is issued by the LL prior to ISDN_CMD_DIAL or
    ISDN_CMD_ACCEPTD.


    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_SETL2
      arg         = channel-number locally to the driver. (starting with 0)
                    logical or'ed with (protocol-Id << 8)
                    protocol-Id is one of the constants ISDN_PROTO_L2...
      parm        = unused.

  ISDN_CMD_GETL2: (currently unused)

    With this command, the HL-driver is told to return the current
    setting of the Layer-2-protocol.

    Parameter:
      driver      = driver-Id.
      command     = ISDN_CMD_GETL2
      arg         = channel-number locally to the driver. (starting with 0)
      parm        = unused.
    Returnvalue:
      current protocol-Id (one of the constants ISDN_L2_PROTO)

  ISDN_CMD_SETL3:

    With this command, the HL-driver is told to select the given Layer-3-
    protocol. This command is issued by the LL prior to ISDN_CMD_DIAL or
    ISDN_CMD_ACCEPTD.