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 bool direct_xmit; /* no qdisc, xmit directly */
46};
47
48#ifdef __KERNEL__
49/* Called by the channel when it can send some more data. */
50extern void ppp_output_wakeup(struct ppp_channel *);
51
52/* Called by the channel to process a received PPP packet.
53 The packet should have just the 2-byte PPP protocol header. */
54extern void ppp_input(struct ppp_channel *, struct sk_buff *);
55
56/* Called by the channel when an input error occurs, indicating
57 that we may have missed a packet. */
58extern void ppp_input_error(struct ppp_channel *, int code);
59
60/* Attach a channel to a given PPP unit in specified net. */
61extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
62
63/* Attach a channel to a given PPP unit. */
64extern int ppp_register_channel(struct ppp_channel *);
65
66/* Detach a channel from its PPP unit (e.g. on hangup). */
67extern void ppp_unregister_channel(struct ppp_channel *);
68
69/* Get the channel number for a channel */
70extern int ppp_channel_index(struct ppp_channel *);
71
72/* Get the unit number associated with a channel, or -1 if none */
73extern int ppp_unit_number(struct ppp_channel *);
74
75/* Get the device name associated with a channel, or NULL if none */
76extern char *ppp_dev_name(struct ppp_channel *);
77
78/*
79 * SMP locking notes:
80 * The channel code must ensure that when it calls ppp_unregister_channel,
81 * nothing is executing in any of the procedures above, for that
82 * channel. The generic layer will ensure that nothing is executing
83 * in the start_xmit and ioctl routines for the channel by the time
84 * that ppp_unregister_channel returns.
85 */
86
87#endif /* __KERNEL__ */
88#endif
89