linux/include/linux/hdlc.h
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   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * Generic HDLC support routines for Linux
   4 *
   5 * Copyright (C) 1999-2005 Krzysztof Halasa <khc@pm.waw.pl>
   6 */
   7#ifndef __HDLC_H
   8#define __HDLC_H
   9
  10
  11#include <linux/skbuff.h>
  12#include <linux/netdevice.h>
  13#include <linux/hdlc/ioctl.h>
  14#include <uapi/linux/hdlc.h>
  15
  16/* This structure is a private property of HDLC protocols.
  17   Hardware drivers have no interest here */
  18
  19struct hdlc_proto {
  20        int (*open)(struct net_device *dev);
  21        void (*close)(struct net_device *dev);
  22        void (*start)(struct net_device *dev); /* if open & DCD */
  23        void (*stop)(struct net_device *dev); /* if open & !DCD */
  24        void (*detach)(struct net_device *dev);
  25        int (*ioctl)(struct net_device *dev, struct ifreq *ifr);
  26        __be16 (*type_trans)(struct sk_buff *skb, struct net_device *dev);
  27        int (*netif_rx)(struct sk_buff *skb);
  28        netdev_tx_t (*xmit)(struct sk_buff *skb, struct net_device *dev);
  29        struct module *module;
  30        struct hdlc_proto *next; /* next protocol in the list */
  31};
  32
  33
  34/* Pointed to by netdev_priv(dev) */
  35typedef struct hdlc_device {
  36        /* used by HDLC layer to take control over HDLC device from hw driver*/
  37        int (*attach)(struct net_device *dev,
  38                      unsigned short encoding, unsigned short parity);
  39
  40        /* hardware driver must handle this instead of dev->hard_start_xmit */
  41        netdev_tx_t (*xmit)(struct sk_buff *skb, struct net_device *dev);
  42
  43        /* Things below are for HDLC layer internal use only */
  44        const struct hdlc_proto *proto;
  45        int carrier;
  46        int open;
  47        spinlock_t state_lock;
  48        void *state;
  49        void *priv;
  50} hdlc_device;
  51
  52
  53
  54/* Exported from hdlc module */
  55
  56/* Called by hardware driver when a user requests HDLC service */
  57int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);
  58
  59/* Must be used by hardware driver on module startup/exit */
  60#define register_hdlc_device(dev)       register_netdev(dev)
  61void unregister_hdlc_device(struct net_device *dev);
  62
  63
  64void register_hdlc_protocol(struct hdlc_proto *proto);
  65void unregister_hdlc_protocol(struct hdlc_proto *proto);
  66
  67struct net_device *alloc_hdlcdev(void *priv);
  68
  69static inline struct hdlc_device* dev_to_hdlc(struct net_device *dev)
  70{
  71        return netdev_priv(dev);
  72}
  73
  74static __inline__ void debug_frame(const struct sk_buff *skb)
  75{
  76        int i;
  77
  78        for (i=0; i < skb->len; i++) {
  79                if (i == 100) {
  80                        printk("...\n");
  81                        return;
  82                }
  83                printk(" %02X", skb->data[i]);
  84        }
  85        printk("\n");
  86}
  87
  88
  89/* Must be called by hardware driver when HDLC device is being opened */
  90int hdlc_open(struct net_device *dev);
  91/* Must be called by hardware driver when HDLC device is being closed */
  92void hdlc_close(struct net_device *dev);
  93/* Must be pointed to by hw driver's dev->netdev_ops->ndo_start_xmit */
  94netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev);
  95
  96int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
  97                         size_t size);
  98/* May be used by hardware driver to gain control over HDLC device */
  99int detach_hdlc_protocol(struct net_device *dev);
 100
 101static __inline__ __be16 hdlc_type_trans(struct sk_buff *skb,
 102                                         struct net_device *dev)
 103{
 104        hdlc_device *hdlc = dev_to_hdlc(dev);
 105
 106        skb->dev = dev;
 107        skb_reset_mac_header(skb);
 108
 109        if (hdlc->proto->type_trans)
 110                return hdlc->proto->type_trans(skb, dev);
 111        else
 112                return htons(ETH_P_HDLC);
 113}
 114
 115#endif /* __HDLC_H */
 116
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