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422 giacomo 1
#ifndef _PPP_CHANNEL_H_
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#define _PPP_CHANNEL_H_
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/*
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 * Definitions for the interface between the generic PPP code
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 * and a PPP channel.
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 *
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 * A PPP channel provides a way for the generic PPP code to send
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 * and receive packets over some sort of communications medium.
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 * Packets are stored in sk_buffs and have the 2-byte PPP protocol
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 * number at the start, but not the address and control bytes.
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 *
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 * Copyright 1999 Paul Mackerras.
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 *
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 *  This program is free software; you can redistribute it and/or
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 *  modify it under the terms of the GNU General Public License
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 *  as published by the Free Software Foundation; either version
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 *  2 of the License, or (at your option) any later version.
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 *
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 * ==FILEVERSION 20000322==
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 */
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#include <linux/list.h>
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#include <linux/skbuff.h>
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#include <linux/poll.h>
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struct ppp_channel;
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struct ppp_channel_ops {
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        /* Send a packet (or multilink fragment) on this channel.
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           Returns 1 if it was accepted, 0 if not. */
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        int     (*start_xmit)(struct ppp_channel *, struct sk_buff *);
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        /* Handle an ioctl call that has come in via /dev/ppp. */
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        int     (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
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};
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struct ppp_channel {
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        void            *private;       /* channel private data */
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        struct ppp_channel_ops *ops;    /* operations for this channel */
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        int             mtu;            /* max transmit packet size */
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        int             hdrlen;         /* amount of headroom channel needs */
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        void            *ppp;           /* opaque to channel */
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        /* the following are not used at present */
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        int             speed;          /* transfer rate (bytes/second) */
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        int             latency;        /* overhead time in milliseconds */
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};
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#ifdef __KERNEL__
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/* Called by the channel when it can send some more data. */
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extern void ppp_output_wakeup(struct ppp_channel *);
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/* Called by the channel to process a received PPP packet.
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   The packet should have just the 2-byte PPP protocol header. */
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extern void ppp_input(struct ppp_channel *, struct sk_buff *);
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/* Called by the channel when an input error occurs, indicating
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   that we may have missed a packet. */
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extern void ppp_input_error(struct ppp_channel *, int code);
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/* Attach a channel to a given PPP unit. */
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extern int ppp_register_channel(struct ppp_channel *);
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/* Detach a channel from its PPP unit (e.g. on hangup). */
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extern void ppp_unregister_channel(struct ppp_channel *);
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/* Get the channel number for a channel */
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extern int ppp_channel_index(struct ppp_channel *);
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/* Get the unit number associated with a channel, or -1 if none */
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extern int ppp_unit_number(struct ppp_channel *);
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/*
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 * SMP locking notes:
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 * The channel code must ensure that when it calls ppp_unregister_channel,
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 * nothing is executing in any of the procedures above, for that
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 * channel.  The generic layer will ensure that nothing is executing
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 * in the start_xmit and ioctl routines for the channel by the time
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 * that ppp_unregister_channel returns.
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 */
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#endif /* __KERNEL__ */
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#endif