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
26struct ppp_channel;
27
28struct 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
36struct 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. */
49extern 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. */
53extern 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. */
57extern void ppp_input_error(struct ppp_channel *, int code);
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/*
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
82