linux/include/linux/hdlc.h
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   1/*
   2 * Generic HDLC support routines for Linux
   3 *
   4 * Copyright (C) 1999-2005 Krzysztof Halasa <khc@pm.waw.pl>
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms of version 2 of the GNU General Public License
   8 * as published by the Free Software Foundation.
   9 */
  10
  11#ifndef __HDLC_H
  12#define __HDLC_H
  13
  14
  15#define HDLC_MAX_MTU 1500       /* Ethernet 1500 bytes */
  16#if 0
  17#define HDLC_MAX_MRU (HDLC_MAX_MTU + 10 + 14 + 4) /* for ETH+VLAN over FR */
  18#else
  19#define HDLC_MAX_MRU 1600 /* as required for FR network */
  20#endif
  21
  22
  23#ifdef __KERNEL__
  24
  25#include <linux/skbuff.h>
  26#include <linux/netdevice.h>
  27#include <linux/hdlc/ioctl.h>
  28
  29/* This structure is a private property of HDLC protocols.
  30   Hardware drivers have no interest here */
  31
  32struct hdlc_proto {
  33        int (*open)(struct net_device *dev);
  34        void (*close)(struct net_device *dev);
  35        void (*start)(struct net_device *dev); /* if open & DCD */
  36        void (*stop)(struct net_device *dev); /* if open & !DCD */
  37        void (*detach)(struct net_device *dev);
  38        int (*ioctl)(struct net_device *dev, struct ifreq *ifr);
  39        __be16 (*type_trans)(struct sk_buff *skb, struct net_device *dev);
  40        int (*netif_rx)(struct sk_buff *skb);
  41        netdev_tx_t (*xmit)(struct sk_buff *skb, struct net_device *dev);
  42        struct module *module;
  43        struct hdlc_proto *next; /* next protocol in the list */
  44};
  45
  46
  47/* Pointed to by netdev_priv(dev) */
  48typedef struct hdlc_device {
  49        /* used by HDLC layer to take control over HDLC device from hw driver*/
  50        int (*attach)(struct net_device *dev,
  51                      unsigned short encoding, unsigned short parity);
  52
  53        /* hardware driver must handle this instead of dev->hard_start_xmit */
  54        netdev_tx_t (*xmit)(struct sk_buff *skb, struct net_device *dev);
  55
  56        /* Things below are for HDLC layer internal use only */
  57        const struct hdlc_proto *proto;
  58        int carrier;
  59        int open;
  60        spinlock_t state_lock;
  61        void *state;
  62        void *priv;
  63} hdlc_device;
  64
  65
  66
  67/* Exported from hdlc module */
  68
  69/* Called by hardware driver when a user requests HDLC service */
  70int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);
  71
  72/* Must be used by hardware driver on module startup/exit */
  73#define register_hdlc_device(dev)       register_netdev(dev)
  74void unregister_hdlc_device(struct net_device *dev);
  75
  76
  77void register_hdlc_protocol(struct hdlc_proto *proto);
  78void unregister_hdlc_protocol(struct hdlc_proto *proto);
  79
  80struct net_device *alloc_hdlcdev(void *priv);
  81
  82static inline struct hdlc_device* dev_to_hdlc(struct net_device *dev)
  83{
  84        return netdev_priv(dev);
  85}
  86
  87static __inline__ void debug_frame(const struct sk_buff *skb)
  88{
  89        int i;
  90
  91        for (i=0; i < skb->len; i++) {
  92                if (i == 100) {
  93                        printk("...\n");
  94                        return;
  95                }
  96                printk(" %02X", skb->data[i]);
  97        }
  98        printk("\n");
  99}
 100
 101
 102/* Must be called by hardware driver when HDLC device is being opened */
 103int hdlc_open(struct net_device *dev);
 104/* Must be called by hardware driver when HDLC device is being closed */
 105void hdlc_close(struct net_device *dev);
 106/* May be used by hardware driver */
 107int hdlc_change_mtu(struct net_device *dev, int new_mtu);
 108/* Must be pointed to by hw driver's dev->netdev_ops->ndo_start_xmit */
 109netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev);
 110
 111int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 112                         size_t size);
 113/* May be used by hardware driver to gain control over HDLC device */
 114void detach_hdlc_protocol(struct net_device *dev);
 115
 116static __inline__ __be16 hdlc_type_trans(struct sk_buff *skb,
 117                                         struct net_device *dev)
 118{
 119        hdlc_device *hdlc = dev_to_hdlc(dev);
 120
 121        skb->dev = dev;
 122        skb_reset_mac_header(skb);
 123
 124        if (hdlc->proto->type_trans)
 125                return hdlc->proto->type_trans(skb, dev);
 126        else
 127                return htons(ETH_P_HDLC);
 128}
 129
 130#endif /* __KERNEL */
 131#endif /* __HDLC_H */
 132
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