include/linux/ppp_channel.h

   1 #ifndef _PPP_CHANNEL_H_
   2 #define _PPP_CHANNEL_H_
   3 /*
   4  * Definitions for the interface between the generic PPP code
   5  * and a PPP channel.
   6  *
   7  * A PPP channel provides a way for the generic PPP code to send
   8  * and receive packets over some sort of communications medium.
   9  * Packets are stored in sk_buffs and have the 2-byte PPP protocol
  10  * number at the start, but not the address and control bytes.
  11  *
  12  * Copyright 1999 Paul Mackerras.
  13  *
  14  *  This program is free software; you can redistribute it and/or
  15  *  modify it under the terms of the GNU General Public License
  16  *  as published by the Free Software Foundation; either version
  17  *  2 of the License, or (at your option) any later version.
  18  *
  19  * ==FILEVERSION 20000322==
  20  */
  21
  22 #include <linux/list.h>
  23 #include <linux/skbuff.h>
  24 #include <linux/poll.h>
  25
  26 struct ppp_channel;
  27
  28 struct ppp_channel_ops {
  29         /* Send a packet (or multilink fragment) on this channel.
  30            Returns 1 if it was accepted, 0 if not. */
  31         int     (*start_xmit)(struct ppp_channel *, struct sk_buff *);
  32         /* Handle an ioctl call that has come in via /dev/ppp. */
  33         int     (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
  34 };
  35
  36 struct ppp_channel {
  37         void            *private;       /* channel private data */
  38         struct ppp_channel_ops *ops;    /* operations for this channel */
  39         int             mtu;            /* max transmit packet size */
  40         int             hdrlen;         /* amount of headroom channel needs */
  41         void            *ppp;           /* opaque to channel */
  42         /* the following are not used at present */
  43         int             speed;          /* transfer rate (bytes/second) */
  44         int             latency;        /* overhead time in milliseconds */
  45 };
  46
  47 #ifdef __KERNEL__
  48 /* Called by the channel when it can send some more data. */
  49 extern void ppp_output_wakeup(struct ppp_channel *);
  50
  51 /* Called by the channel to process a received PPP packet.
  52    The packet should have just the 2-byte PPP protocol header. */
  53 extern void ppp_input(struct ppp_channel *, struct sk_buff *);
  54
  55 /* Called by the channel when an input error occurs, indicating
  56    that we may have missed a packet. */
  57 extern void ppp_input_error(struct ppp_channel *, int code);
  58
  59 /* Attach a channel to a given PPP unit. */
  60 extern int ppp_register_channel(struct ppp_channel *);
  61
  62 /* Detach a channel from its PPP unit (e.g. on hangup). */
  63 extern void ppp_unregister_channel(struct ppp_channel *);
  64
  65 /* Get the channel number for a channel */
  66 extern int ppp_channel_index(struct ppp_channel *);
  67
  68 /* Get the unit number associated with a channel, or -1 if none */
  69 extern int ppp_unit_number(struct ppp_channel *);
  70
  71 /*
  72  * SMP locking notes:
  73  * The channel code must ensure that when it calls ppp_unregister_channel,
  74  * nothing is executing in any of the procedures above, for that
  75  * channel.  The generic layer will ensure that nothing is executing
  76  * in the start_xmit and ioctl routines for the channel by the time
  77  * that ppp_unregister_channel returns.
  78  */
  79
  80 #endif /* __KERNEL__ */
  81 #endif