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 net_device_path;
24struct net_device_path_ctx;
25struct ppp_channel;
26
27struct ppp_channel_ops {
28	/* Send a packet (or multilink fragment) on this channel.
29	   Returns 1 if it was accepted, 0 if not. */
30	int	(*start_xmit)(struct ppp_channel *, struct sk_buff *);
31	/* Handle an ioctl call that has come in via /dev/ppp. */
32	int	(*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
33	int	(*fill_forward_path)(struct net_device_path_ctx *,
34				     struct net_device_path *,
35				     const struct ppp_channel *);
36};
37
38struct ppp_channel {
39	void		*private;	/* channel private data */
40	const 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	int		speed;		/* transfer rate (bytes/second) */
45	/* the following is not used at present */
46	int		latency;	/* overhead time in milliseconds */
47};
48
49#ifdef __KERNEL__
50/* Called by the channel when it can send some more data. */
51extern 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. */
55extern 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. */
59extern void ppp_input_error(struct ppp_channel *, int code);
60
61/* Attach a channel to a given PPP unit in specified net. */
62extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
63
64/* Attach a channel to a given PPP unit. */
65extern int ppp_register_channel(struct ppp_channel *);
66
67/* Detach a channel from its PPP unit (e.g. on hangup). */
68extern void ppp_unregister_channel(struct ppp_channel *);
69
70/* Get the channel number for a channel */
71extern int ppp_channel_index(struct ppp_channel *);
72
73/* Get the unit number associated with a channel, or -1 if none */
74extern int ppp_unit_number(struct ppp_channel *);
75
76/* Get the device name associated with a channel, or NULL if none */
77extern char *ppp_dev_name(struct ppp_channel *);
78
79/*
80 * SMP locking notes:
81 * The channel code must ensure that when it calls ppp_unregister_channel,
82 * nothing is executing in any of the procedures above, for that
83 * channel.  The generic layer will ensure that nothing is executing
84 * in the start_xmit and ioctl routines for the channel by the time
85 * that ppp_unregister_channel returns.
86 */
87
88#endif /* __KERNEL__ */
89#endif
90