include/linux/ppp_channel.h

   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
  23 struct ppp_channel;
  24
  25 struct 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         int     (*fill_forward_path)(struct net_device_path_ctx *,
  32                                      struct net_device_path *,
  33                                      const struct ppp_channel *);
  34 };
  35
  36 struct ppp_channel {
  37         void            *private;       /* channel private data */
  38         const 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         int             speed;          /* transfer rate (bytes/second) */
  43         /* the following is not used at present */
  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 in specified net. */
  60 extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
  61
  62 /* Attach a channel to a given PPP unit. */
  63 extern int ppp_register_channel(struct ppp_channel *);
  64
  65 /* Detach a channel from its PPP unit (e.g. on hangup). */
  66 extern void ppp_unregister_channel(struct ppp_channel *);
  67
  68 /* Get the channel number for a channel */
  69 extern int ppp_channel_index(struct ppp_channel *);
  70
  71 /* Get the unit number associated with a channel, or -1 if none */
  72 extern int ppp_unit_number(struct ppp_channel *);
  73
  74 /* Get the device name associated with a channel, or NULL if none */
  75 extern char *ppp_dev_name(struct ppp_channel *);
  76
  77 /*
  78  * SMP locking notes:
  79  * The channel code must ensure that when it calls ppp_unregister_channel,
  80  * nothing is executing in any of the procedures above, for that
  81  * channel.  The generic layer will ensure that nothing is executing
  82  * in the start_xmit and ioctl routines for the channel by the time
  83  * that ppp_unregister_channel returns.
  84  */
  85
  86 #endif /* __KERNEL__ */
  87 #endif