include/linux/ppp_channel.h

0001 /* SPDX-License-Identifier: GPL-2.0-or-later */
0002 #ifndef _PPP_CHANNEL_H_
0003 #define _PPP_CHANNEL_H_
0004 /*
0005  * Definitions for the interface between the generic PPP code
0006  * and a PPP channel.
0007  *
0008  * A PPP channel provides a way for the generic PPP code to send
0009  * and receive packets over some sort of communications medium.
0010  * Packets are stored in sk_buffs and have the 2-byte PPP protocol
0011  * number at the start, but not the address and control bytes.
0012  *
0013  * Copyright 1999 Paul Mackerras.
0014  *
0015  * ==FILEVERSION 20000322==
0016  */
0017
0018 #include <linux/list.h>
0019 #include <linux/skbuff.h>
0020 #include <linux/poll.h>
0021 #include <net/net_namespace.h>
0022
0023 struct net_device_path;
0024 struct net_device_path_ctx;
0025 struct ppp_channel;
0026
0027 struct ppp_channel_ops {
0028     /* Send a packet (or multilink fragment) on this channel.
0029        Returns 1 if it was accepted, 0 if not. */
0030     int (*start_xmit)(struct ppp_channel *, struct sk_buff *);
0031     /* Handle an ioctl call that has come in via /dev/ppp. */
0032     int (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
0033     int (*fill_forward_path)(struct net_device_path_ctx *,
0034                      struct net_device_path *,
0035                      const struct ppp_channel *);
0036 };
0037
0038 struct ppp_channel {
0039     void        *private;   /* channel private data */
0040     const struct ppp_channel_ops *ops; /* operations for this channel */
0041     int     mtu;        /* max transmit packet size */
0042     int     hdrlen;     /* amount of headroom channel needs */
0043     void        *ppp;       /* opaque to channel */
0044     int     speed;      /* transfer rate (bytes/second) */
0045     /* the following is not used at present */
0046     int     latency;    /* overhead time in milliseconds */
0047 };
0048
0049 #ifdef __KERNEL__
0050 /* Called by the channel when it can send some more data. */
0051 extern void ppp_output_wakeup(struct ppp_channel *);
0052
0053 /* Called by the channel to process a received PPP packet.
0054    The packet should have just the 2-byte PPP protocol header. */
0055 extern void ppp_input(struct ppp_channel *, struct sk_buff *);
0056
0057 /* Called by the channel when an input error occurs, indicating
0058    that we may have missed a packet. */
0059 extern void ppp_input_error(struct ppp_channel *, int code);
0060
0061 /* Attach a channel to a given PPP unit in specified net. */
0062 extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
0063
0064 /* Attach a channel to a given PPP unit. */
0065 extern int ppp_register_channel(struct ppp_channel *);
0066
0067 /* Detach a channel from its PPP unit (e.g. on hangup). */
0068 extern void ppp_unregister_channel(struct ppp_channel *);
0069
0070 /* Get the channel number for a channel */
0071 extern int ppp_channel_index(struct ppp_channel *);
0072
0073 /* Get the unit number associated with a channel, or -1 if none */
0074 extern int ppp_unit_number(struct ppp_channel *);
0075
0076 /* Get the device name associated with a channel, or NULL if none */
0077 extern char *ppp_dev_name(struct ppp_channel *);
0078
0079 /*
0080  * SMP locking notes:
0081  * The channel code must ensure that when it calls ppp_unregister_channel,
0082  * nothing is executing in any of the procedures above, for that
0083  * channel.  The generic layer will ensure that nothing is executing
0084  * in the start_xmit and ioctl routines for the channel by the time
0085  * that ppp_unregister_channel returns.
0086  */
0087
0088 #endif /* __KERNEL__ */
0089 #endif