LXR linux/include/linux/ppp

   1/* SPDX-License-Identifier: GPL-2.0-or-later */
   2#ifndef _PPP_CHANNEL_H_
   3#define _PPP_CHANNEL_H_
   4/*
   5 * Definitions for the interface between the generic PPP code
   6 * and a PPP channel.
   7 *
   8 * A PPP channel provides a way for the generic PPP code to send
   9 * and receive packets over some sort of communications medium.
  10 * Packets are stored in sk_buffs and have the 2-byte PPP protocol
  11 * number at the start, but not the address and control bytes.
  12 *
  13 * Copyright 1999 Paul Mackerras.
  14 *
  15 * ==FILEVERSION 20000322==
  16 */
  17
  18#include <linux/list.h>
  19#include <linux/skbuff.h>
  20#include <linux/poll.h>
  21#include <net/net_namespace.h>
  22
  23struct ppp_channel;
  24
  25struct ppp_channel_ops {
  26        /* Send a packet (or multilink fragment) on this channel.
  27           Returns 1 if it was accepted, 0 if not. */
  28        int     (*start_xmit)(struct ppp_channel *, struct sk_buff *);
  29        /* Handle an ioctl call that has come in via /dev/ppp. */
  30        int     (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
  31};
  32
  33struct ppp_channel {
  34        void            *private;       /* channel private data */
  35        const struct ppp_channel_ops *ops; /* operations for this channel */
  36        int             mtu;            /* max transmit packet size */
  37        int             hdrlen;         /* amount of headroom channel needs */
  38        void            *ppp;           /* opaque to channel */
  39        int             speed;          /* transfer rate (bytes/second) */
  40        /* the following is not used at present */
  41        int             latency;        /* overhead time in milliseconds */
  42};
  43
  44#ifdef __KERNEL__
  45/* Called by the channel when it can send some more data. */
  46extern void ppp_output_wakeup(struct ppp_channel *);
  47
  48/* Called by the channel to process a received PPP packet.
  49   The packet should have just the 2-byte PPP protocol header. */
  50extern void ppp_input(struct ppp_channel *, struct sk_buff *);
  51
  52/* Called by the channel when an input error occurs, indicating
  53   that we may have missed a packet. */
  54extern void ppp_input_error(struct ppp_channel *, int code);
  55
  56/* Attach a channel to a given PPP unit in specified net. */
  57extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
  58
  59/* Attach a channel to a given PPP unit. */
  60extern int ppp_register_channel(struct ppp_channel *);
  61
  62/* Detach a channel from its PPP unit (e.g. on hangup). */
  63extern void ppp_unregister_channel(struct ppp_channel *);
  64
  65/* Get the channel number for a channel */
  66extern int ppp_channel_index(struct ppp_channel *);
  67
  68/* Get the unit number associated with a channel, or -1 if none */
  69extern int ppp_unit_number(struct ppp_channel *);
  70
  71/* Get the device name associated with a channel, or NULL if none */
  72extern char *ppp_dev_name(struct ppp_channel *);
  73
  74/*
  75 * SMP locking notes:
  76 * The channel code must ensure that when it calls ppp_unregister_channel,
  77 * nothing is executing in any of the procedures above, for that
  78 * channel.  The generic layer will ensure that nothing is executing
  79 * in the start_xmit and ioctl routines for the channel by the time
  80 * that ppp_unregister_channel returns.
  81 */
  82
  83#endif /* __KERNEL__ */
  84#endif
  85