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 #include <asm/atomic.h>
  26
  27 struct ppp_channel;
  28
  29 struct ppp_channel_ops {
  30         /* Send a packet (or multilink fragment) on this channel.
  31            Returns 1 if it was accepted, 0 if not. */
  32         int     (*start_xmit)(struct ppp_channel *, struct sk_buff *);
  33         /* Handle an ioctl call that has come in via /dev/ppp. */
  34         int     (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
  35
  36 };
  37
  38 struct ppp_channel {
  39         void            *private;       /* channel private data */
  40         struct ppp_channel_ops *ops;    /* operations for this channel */
  41         int             mtu;            /* max transmit packet size */
  42         int             hdrlen;         /* amount of headroom channel needs */
  43         void            *ppp;           /* opaque to channel */
  44         /* the following are not used at present */
  45         int             speed;          /* transfer rate (bytes/second) */
  46         int             latency;        /* overhead time in milliseconds */
  47 };
  48
  49 #ifdef __KERNEL__
  50 /* Called by the channel when it can send some more data. */
  51 extern void ppp_output_wakeup(struct ppp_channel *);
  52
  53 /* Called by the channel to process a received PPP packet.
  54    The packet should have just the 2-byte PPP protocol header. */
  55 extern void ppp_input(struct ppp_channel *, struct sk_buff *);
  56
  57 /* Called by the channel when an input error occurs, indicating
  58    that we may have missed a packet. */
  59 extern void ppp_input_error(struct ppp_channel *, int code);
  60
  61 /* Attach a channel to a given PPP unit. */
  62 extern int ppp_register_channel(struct ppp_channel *);
  63
  64 /* Detach a channel from its PPP unit (e.g. on hangup). */
  65 extern void ppp_unregister_channel(struct ppp_channel *);
  66
  67 /* Get the channel number for a channel */
  68 extern int ppp_channel_index(struct ppp_channel *);
  69
  70 /* Get the unit number associated with a channel, or -1 if none */
  71 extern int ppp_unit_number(struct ppp_channel *);
  72
  73 /*
  74  * SMP locking notes:
  75  * The channel code must ensure that when it calls ppp_unregister_channel,
  76  * nothing is executing in any of the procedures above, for that
  77  * channel.  The generic layer will ensure that nothing is executing
  78  * in the start_xmit and ioctl routines for the channel by the time
  79  * that ppp_unregister_channel returns.
  80  */
  81
  82 /* The following are temporary compatibility stuff */
  83 ssize_t ppp_channel_read(struct ppp_channel *chan, struct file *file,
  84                          char *buf, size_t count);
  85 ssize_t ppp_channel_write(struct ppp_channel *chan, const char *buf,
  86                           size_t count);
  87 unsigned int ppp_channel_poll(struct ppp_channel *chan, struct file *file,
  88                               poll_table *wait);
  89 int ppp_channel_ioctl(struct ppp_channel *chan, unsigned int cmd,
  90                       unsigned long arg);
  91
  92 #endif /* __KERNEL__ */
  93 #endif