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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 #ifndef __HDLC_H
11 #define __HDLC_H
12 
13 
14 #include <linux/skbuff.h>
15 #include <linux/netdevice.h>
16 #include <linux/hdlc/ioctl.h>
17 #include <uapi/linux/hdlc.h>
18 
19 /* This structure is a private property of HDLC protocols.
20    Hardware drivers have no interest here */
21 
22 struct hdlc_proto {
23 	int (*open)(struct net_device *dev);
24 	void (*close)(struct net_device *dev);
25 	void (*start)(struct net_device *dev); /* if open & DCD */
26 	void (*stop)(struct net_device *dev); /* if open & !DCD */
27 	void (*detach)(struct net_device *dev);
28 	int (*ioctl)(struct net_device *dev, struct ifreq *ifr);
29 	__be16 (*type_trans)(struct sk_buff *skb, struct net_device *dev);
30 	int (*netif_rx)(struct sk_buff *skb);
31 	netdev_tx_t (*xmit)(struct sk_buff *skb, struct net_device *dev);
32 	struct module *module;
33 	struct hdlc_proto *next; /* next protocol in the list */
34 };
35 
36 
37 /* Pointed to by netdev_priv(dev) */
38 typedef struct hdlc_device {
39 	/* used by HDLC layer to take control over HDLC device from hw driver*/
40 	int (*attach)(struct net_device *dev,
41 		      unsigned short encoding, unsigned short parity);
42 
43 	/* hardware driver must handle this instead of dev->hard_start_xmit */
44 	netdev_tx_t (*xmit)(struct sk_buff *skb, struct net_device *dev);
45 
46 	/* Things below are for HDLC layer internal use only */
47 	const struct hdlc_proto *proto;
48 	int carrier;
49 	int open;
50 	spinlock_t state_lock;
51 	void *state;
52 	void *priv;
53 } hdlc_device;
54 
55 
56 
57 /* Exported from hdlc module */
58 
59 /* Called by hardware driver when a user requests HDLC service */
60 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);
61 
62 /* Must be used by hardware driver on module startup/exit */
63 #define register_hdlc_device(dev)	register_netdev(dev)
64 void unregister_hdlc_device(struct net_device *dev);
65 
66 
67 void register_hdlc_protocol(struct hdlc_proto *proto);
68 void unregister_hdlc_protocol(struct hdlc_proto *proto);
69 
70 struct net_device *alloc_hdlcdev(void *priv);
71 
dev_to_hdlc(struct net_device * dev)72 static inline struct hdlc_device* dev_to_hdlc(struct net_device *dev)
73 {
74 	return netdev_priv(dev);
75 }
76 
debug_frame(const struct sk_buff * skb)77 static __inline__ void debug_frame(const struct sk_buff *skb)
78 {
79 	int i;
80 
81 	for (i=0; i < skb->len; i++) {
82 		if (i == 100) {
83 			printk("...\n");
84 			return;
85 		}
86 		printk(" %02X", skb->data[i]);
87 	}
88 	printk("\n");
89 }
90 
91 
92 /* Must be called by hardware driver when HDLC device is being opened */
93 int hdlc_open(struct net_device *dev);
94 /* Must be called by hardware driver when HDLC device is being closed */
95 void hdlc_close(struct net_device *dev);
96 /* May be used by hardware driver */
97 int hdlc_change_mtu(struct net_device *dev, int new_mtu);
98 /* Must be pointed to by hw driver's dev->netdev_ops->ndo_start_xmit */
99 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev);
100 
101 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
102 			 size_t size);
103 /* May be used by hardware driver to gain control over HDLC device */
104 void detach_hdlc_protocol(struct net_device *dev);
105 
hdlc_type_trans(struct sk_buff * skb,struct net_device * dev)106 static __inline__ __be16 hdlc_type_trans(struct sk_buff *skb,
107 					 struct net_device *dev)
108 {
109 	hdlc_device *hdlc = dev_to_hdlc(dev);
110 
111 	skb->dev = dev;
112 	skb_reset_mac_header(skb);
113 
114 	if (hdlc->proto->type_trans)
115 		return hdlc->proto->type_trans(skb, dev);
116 	else
117 		return htons(ETH_P_HDLC);
118 }
119 
120 #endif /* __HDLC_H */
121