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 net_device_path;
24 struct net_device_path_ctx;
25 struct ppp_channel;
26
27 struct 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
38 struct 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. */
51 extern 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. */
55 extern 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. */
59 extern void ppp_input_error(struct ppp_channel *, int code);
60
61 /* Attach a channel to a given PPP unit in specified net. */
62 extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
63
64 /* Attach a channel to a given PPP unit. */
65 extern int ppp_register_channel(struct ppp_channel *);
66
67 /* Detach a channel from its PPP unit (e.g. on hangup). */
68 extern void ppp_unregister_channel(struct ppp_channel *);
69
70 /* Get the channel number for a channel */
71 extern int ppp_channel_index(struct ppp_channel *);
72
73 /* Get the unit number associated with a channel, or -1 if none */
74 extern int ppp_unit_number(struct ppp_channel *);
75
76 /* Get the device name associated with a channel, or NULL if none */
77 extern 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
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