Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  1 #ifndef _PPP_CHANNEL_H_
  2 #define _PPP_CHANNEL_H_
  3 /*
  4  * Definitions for the interface between the generic PPP code
  5  * and a PPP channel.
  6  *
  7  * A PPP channel provides a way for the generic PPP code to send
  8  * and receive packets over some sort of communications medium.
  9  * Packets are stored in sk_buffs and have the 2-byte PPP protocol
 10  * number at the start, but not the address and control bytes.
 11  *
 12  * Copyright 1999 Paul Mackerras.
 13  *
 14  *  This program is free software; you can redistribute it and/or
 15  *  modify it under the terms of the GNU General Public License
 16  *  as published by the Free Software Foundation; either version
 17  *  2 of the License, or (at your option) any later version.
 18  *
 19  * ==FILEVERSION 20000322==
 20  */
 21 
 22 #include <linux/list.h>
 23 #include <linux/skbuff.h>
 24 #include <linux/poll.h>
 25 #include <net/net_namespace.h>
 26 
 27 struct ppp_channel;
 28 
 29 struct ppp_channel_ops {
 30         /* Send a packet (or multilink fragment) on this channel.
 31            Returns 1 if it was accepted, 0 if not. */
 32         int     (*start_xmit)(struct ppp_channel *, struct sk_buff *);
 33         /* Handle an ioctl call that has come in via /dev/ppp. */
 34         int     (*ioctl)(struct ppp_channel *, unsigned int, unsigned long);
 35 };
 36 
 37 struct ppp_channel {
 38         void            *private;       /* channel private data */
 39         struct ppp_channel_ops *ops;    /* operations for this channel */
 40         int             mtu;            /* max transmit packet size */
 41         int             hdrlen;         /* amount of headroom channel needs */
 42         void            *ppp;           /* opaque to channel */
 43         int             speed;          /* transfer rate (bytes/second) */
 44         /* the following is not used at present */
 45         int             latency;        /* overhead time in milliseconds */
 46 };
 47 
 48 #ifdef __KERNEL__
 49 /* Called by the channel when it can send some more data. */
 50 extern 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. */
 54 extern 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. */
 58 extern void ppp_input_error(struct ppp_channel *, int code);
 59 
 60 /* Attach a channel to a given PPP unit in specified net. */
 61 extern int ppp_register_net_channel(struct net *, struct ppp_channel *);
 62 
 63 /* Attach a channel to a given PPP unit. */
 64 extern int ppp_register_channel(struct ppp_channel *);
 65 
 66 /* Detach a channel from its PPP unit (e.g. on hangup). */
 67 extern void ppp_unregister_channel(struct ppp_channel *);
 68 
 69 /* Get the channel number for a channel */
 70 extern int ppp_channel_index(struct ppp_channel *);
 71 
 72 /* Get the unit number associated with a channel, or -1 if none */
 73 extern int ppp_unit_number(struct ppp_channel *);
 74 
 75 /*
 76  * SMP locking notes:
 77  * The channel code must ensure that when it calls ppp_unregister_channel,
 78  * nothing is executing in any of the procedures above, for that
 79  * channel.  The generic layer will ensure that nothing is executing
 80  * in the start_xmit and ioctl routines for the channel by the time
 81  * that ppp_unregister_channel returns.
 82  */
 83 
 84 #endif /* __KERNEL__ */
 85 #endif
 86 
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