drivers/net/wan/hdlc.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Generic HDLC support routines for Linux
  *
  * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
  *
  * Currently supported:
  *	* raw IP-in-HDLC
  *	* Cisco HDLC
  *	* Frame Relay with ANSI or CCITT LMI (both user and network side)
  *	* PPP
  *	* X.25
  *
  * Use sethdlc utility to set line parameters, protocol and PVCs
  *
  * How does it work:
  * - proto->open(), close(), start(), stop() calls are serialized.
  *   The order is: open, [ start, stop ... ] close ...
  * - proto->start() and stop() are called with spin_lock_irq held.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/errno.h>
 #include <linux/hdlc.h>
 #include <linux/if_arp.h>
 #include <linux/inetdevice.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/notifier.h>
 #include <linux/pkt_sched.h>
 #include <linux/poll.h>
 #include <linux/rtnetlink.h>
 #include <linux/skbuff.h>
 #include <linux/slab.h>
 #include <net/net_namespace.h>


 static const char* version = "HDLC support module revision 1.22";

 #undef DEBUG_LINK

 static struct hdlc_proto *first_proto;

 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
 		    struct packet_type *p, struct net_device *orig_dev)
 {
 	struct hdlc_device *hdlc = dev_to_hdlc(dev);

 	if (!net_eq(dev_net(dev), &init_net)) {
 		kfree_skb(skb);
 		return 0;
 	}

 	BUG_ON(!hdlc->proto->netif_rx);
 	return hdlc->proto->netif_rx(skb);
 }

 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);

 	if (hdlc->proto->xmit)
 		return hdlc->proto->xmit(skb, dev);

 	return hdlc->xmit(skb, dev); /* call hardware driver directly */
 }

 static inline void hdlc_proto_start(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);
 	if (hdlc->proto->start)
 		hdlc->proto->start(dev);
 }


 static inline void hdlc_proto_stop(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);
 	if (hdlc->proto->stop)
 		hdlc->proto->stop(dev);
 }


 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
 			     void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 	hdlc_device *hdlc;
 	unsigned long flags;
 	int on;

 	if (!net_eq(dev_net(dev), &init_net))
 		return NOTIFY_DONE;

 	if (!(dev->priv_flags & IFF_WAN_HDLC))
 		return NOTIFY_DONE; /* not an HDLC device */

 	if (event != NETDEV_CHANGE)
 		return NOTIFY_DONE; /* Only interested in carrier changes */

 	on = netif_carrier_ok(dev);

 #ifdef DEBUG_LINK
 	printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 	       dev->name, on);
 #endif

 	hdlc = dev_to_hdlc(dev);
 	spin_lock_irqsave(&hdlc->state_lock, flags);

 	if (hdlc->carrier == on)
 		goto carrier_exit; /* no change in DCD line level */

 	hdlc->carrier = on;

 	if (!hdlc->open)
 		goto carrier_exit;

 	if (hdlc->carrier) {
 		netdev_info(dev, "Carrier detected\n");
 		hdlc_proto_start(dev);
 	} else {
 		netdev_info(dev, "Carrier lost\n");
 		hdlc_proto_stop(dev);
 	}

 carrier_exit:
 	spin_unlock_irqrestore(&hdlc->state_lock, flags);
 	return NOTIFY_DONE;
 }


 /* Must be called by hardware driver when HDLC device is being opened */
 int hdlc_open(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);
 #ifdef DEBUG_LINK
 	printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 	       hdlc->carrier, hdlc->open);
 #endif

 	if (hdlc->proto == NULL)
 		return -ENOSYS;	/* no protocol attached */

 	if (hdlc->proto->open) {
 		int result = hdlc->proto->open(dev);
 		if (result)
 			return result;
 	}

 	spin_lock_irq(&hdlc->state_lock);

 	if (hdlc->carrier) {
 		netdev_info(dev, "Carrier detected\n");
 		hdlc_proto_start(dev);
 	} else
 		netdev_info(dev, "No carrier\n");

 	hdlc->open = 1;

 	spin_unlock_irq(&hdlc->state_lock);
 	return 0;
 }


 /* Must be called by hardware driver when HDLC device is being closed */
 void hdlc_close(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);
 #ifdef DEBUG_LINK
 	printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 	       hdlc->carrier, hdlc->open);
 #endif

 	spin_lock_irq(&hdlc->state_lock);

 	hdlc->open = 0;
 	if (hdlc->carrier)
 		hdlc_proto_stop(dev);

 	spin_unlock_irq(&hdlc->state_lock);

 	if (hdlc->proto->close)
 		hdlc->proto->close(dev);
 }


 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 {
 	struct hdlc_proto *proto = first_proto;
 	int result;

 	if (cmd != SIOCWANDEV)
 		return -EINVAL;

 	if (dev_to_hdlc(dev)->proto) {
 		result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 		if (result != -EINVAL)
 			return result;
 	}

 	/* Not handled by currently attached protocol (if any) */

 	while (proto) {
 		if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 			return result;
 		proto = proto->next;
 	}
 	return -EINVAL;
 }

 static const struct header_ops hdlc_null_ops;

 static void hdlc_setup_dev(struct net_device *dev)
 {
 	/* Re-init all variables changed by HDLC protocol drivers,
 	 * including ether_setup() called from hdlc_raw_eth.c.
 	 */
 	dev->flags		 = IFF_POINTOPOINT | IFF_NOARP;
 	dev->priv_flags		 = IFF_WAN_HDLC;
 	dev->mtu		 = HDLC_MAX_MTU;
 	dev->min_mtu		 = 68;
 	dev->max_mtu		 = HDLC_MAX_MTU;
 	dev->type		 = ARPHRD_RAWHDLC;
 	dev->hard_header_len	 = 16;
 	dev->addr_len		 = 0;
 	dev->header_ops		 = &hdlc_null_ops;
 }

 static void hdlc_setup(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);

 	hdlc_setup_dev(dev);
 	hdlc->carrier = 1;
 	hdlc->open = 0;
 	spin_lock_init(&hdlc->state_lock);
 }

 struct net_device *alloc_hdlcdev(void *priv)
 {
 	struct net_device *dev;
 	dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 			   NET_NAME_UNKNOWN, hdlc_setup);
 	if (dev)
 		dev_to_hdlc(dev)->priv = priv;
 	return dev;
 }

 void unregister_hdlc_device(struct net_device *dev)
 {
 	rtnl_lock();
 	detach_hdlc_protocol(dev);
 	unregister_netdevice(dev);
 	rtnl_unlock();
 }


 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 			 size_t size)
 {
 	int err;

 	err = detach_hdlc_protocol(dev);
 	if (err)
 		return err;

 	if (!try_module_get(proto->module))
 		return -ENOSYS;

 	if (size) {
 		dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 		if (dev_to_hdlc(dev)->state == NULL) {
 			module_put(proto->module);
 			return -ENOBUFS;
 		}
 	}
 	dev_to_hdlc(dev)->proto = proto;

 	return 0;
 }


 int detach_hdlc_protocol(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);
 	int err;

 	if (hdlc->proto) {
 		err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
 		err = notifier_to_errno(err);
 		if (err) {
 			netdev_err(dev, "Refused to change device type\n");
 			return err;
 		}

 		if (hdlc->proto->detach)
 			hdlc->proto->detach(dev);
 		module_put(hdlc->proto->module);
 		hdlc->proto = NULL;
 	}
 	kfree(hdlc->state);
 	hdlc->state = NULL;
 	hdlc_setup_dev(dev);

 	return 0;
 }


 void register_hdlc_protocol(struct hdlc_proto *proto)
 {
 	rtnl_lock();
 	proto->next = first_proto;
 	first_proto = proto;
 	rtnl_unlock();
 }


 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 {
 	struct hdlc_proto **p;

 	rtnl_lock();
 	p = &first_proto;
 	while (*p != proto) {
 		BUG_ON(!*p);
 		p = &((*p)->next);
 	}
 	*p = proto->next;
 	rtnl_unlock();
 }


 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 MODULE_DESCRIPTION("HDLC support module");
 MODULE_LICENSE("GPL v2");

 EXPORT_SYMBOL(hdlc_start_xmit);
 EXPORT_SYMBOL(hdlc_open);
 EXPORT_SYMBOL(hdlc_close);
 EXPORT_SYMBOL(hdlc_ioctl);
 EXPORT_SYMBOL(alloc_hdlcdev);
 EXPORT_SYMBOL(unregister_hdlc_device);
 EXPORT_SYMBOL(register_hdlc_protocol);
 EXPORT_SYMBOL(unregister_hdlc_protocol);
 EXPORT_SYMBOL(attach_hdlc_protocol);
 EXPORT_SYMBOL(detach_hdlc_protocol);

 static struct packet_type hdlc_packet_type __read_mostly = {
 	.type = cpu_to_be16(ETH_P_HDLC),
 	.func = hdlc_rcv,
 };


 static struct notifier_block hdlc_notifier = {
 	.notifier_call = hdlc_device_event,
 };


 static int __init hdlc_module_init(void)
 {
 	int result;

 	pr_info("%s\n", version);
 	if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 		return result;
 	dev_add_pack(&hdlc_packet_type);
 	return 0;
 }


 static void __exit hdlc_module_exit(void)
 {
 	dev_remove_pack(&hdlc_packet_type);
 	unregister_netdevice_notifier(&hdlc_notifier);
 }


 module_init(hdlc_module_init);
 module_exit(hdlc_module_exit);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Generic HDLC support routines for Linux
	*
	* Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
	*
	* Currently supported:
	* * raw IP-in-HDLC
	* * Cisco HDLC
	* * Frame Relay with ANSI or CCITT LMI (both user and network side)
	* * PPP
	* * X.25
	*
	* Use sethdlc utility to set line parameters, protocol and PVCs
	*
	* How does it work:
	* - proto->open(), close(), start(), stop() calls are serialized.
	* The order is: open, [ start, stop ... ] close ...
	* - proto->start() and stop() are called with spin_lock_irq held.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/errno.h>
	#include <linux/hdlc.h>
	#include <linux/if_arp.h>
	#include <linux/inetdevice.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/notifier.h>
	#include <linux/pkt_sched.h>
	#include <linux/poll.h>
	#include <linux/rtnetlink.h>
	#include <linux/skbuff.h>
	#include <linux/slab.h>
	#include <net/net_namespace.h>


	static const char* version = "HDLC support module revision 1.22";

	#undef DEBUG_LINK

	static struct hdlc_proto *first_proto;

	static int hdlc_rcv(struct sk_buff skb, struct net_device dev,
	struct packet_type p, struct net_device orig_dev)
	{
	struct hdlc_device *hdlc = dev_to_hdlc(dev);

	if (!net_eq(dev_net(dev), &init_net)) {
	kfree_skb(skb);
	return 0;
	}

	BUG_ON(!hdlc->proto->netif_rx);
	return hdlc->proto->netif_rx(skb);
	}

	netdev_tx_t hdlc_start_xmit(struct sk_buff skb, struct net_device dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);

	if (hdlc->proto->xmit)
	return hdlc->proto->xmit(skb, dev);

	return hdlc->xmit(skb, dev); /* call hardware driver directly */
	}

	static inline void hdlc_proto_start(struct net_device *dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	if (hdlc->proto->start)
	hdlc->proto->start(dev);
	}



	static inline void hdlc_proto_stop(struct net_device *dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	if (hdlc->proto->stop)
	hdlc->proto->stop(dev);
	}



	static int hdlc_device_event(struct notifier_block *this, unsigned long event,
	void *ptr)
	{
	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
	hdlc_device *hdlc;
	unsigned long flags;
	int on;

	if (!net_eq(dev_net(dev), &init_net))
	return NOTIFY_DONE;

	if (!(dev->priv_flags & IFF_WAN_HDLC))
	return NOTIFY_DONE; /* not an HDLC device */

	if (event != NETDEV_CHANGE)
	return NOTIFY_DONE; /* Only interested in carrier changes */

	on = netif_carrier_ok(dev);

	#ifdef DEBUG_LINK
	printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
	dev->name, on);
	#endif

	hdlc = dev_to_hdlc(dev);
	spin_lock_irqsave(&hdlc->state_lock, flags);

	if (hdlc->carrier == on)
	goto carrier_exit; /* no change in DCD line level */

	hdlc->carrier = on;

	if (!hdlc->open)
	goto carrier_exit;

	if (hdlc->carrier) {
	netdev_info(dev, "Carrier detected\n");
	hdlc_proto_start(dev);
	} else {
	netdev_info(dev, "Carrier lost\n");
	hdlc_proto_stop(dev);
	}

	carrier_exit:
	spin_unlock_irqrestore(&hdlc->state_lock, flags);
	return NOTIFY_DONE;
	}



	/* Must be called by hardware driver when HDLC device is being opened */
	int hdlc_open(struct net_device *dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	#ifdef DEBUG_LINK
	printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
	hdlc->carrier, hdlc->open);
	#endif

	if (hdlc->proto == NULL)
	return -ENOSYS; /* no protocol attached */

	if (hdlc->proto->open) {
	int result = hdlc->proto->open(dev);
	if (result)
	return result;
	}

	spin_lock_irq(&hdlc->state_lock);

	if (hdlc->carrier) {
	netdev_info(dev, "Carrier detected\n");
	hdlc_proto_start(dev);
	} else
	netdev_info(dev, "No carrier\n");

	hdlc->open = 1;

	spin_unlock_irq(&hdlc->state_lock);
	return 0;
	}



	/* Must be called by hardware driver when HDLC device is being closed */
	void hdlc_close(struct net_device *dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	#ifdef DEBUG_LINK
	printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
	hdlc->carrier, hdlc->open);
	#endif

	spin_lock_irq(&hdlc->state_lock);

	hdlc->open = 0;
	if (hdlc->carrier)
	hdlc_proto_stop(dev);

	spin_unlock_irq(&hdlc->state_lock);

	if (hdlc->proto->close)
	hdlc->proto->close(dev);
	}



	int hdlc_ioctl(struct net_device dev, struct ifreq ifr, int cmd)
	{
	struct hdlc_proto *proto = first_proto;
	int result;

	if (cmd != SIOCWANDEV)
	return -EINVAL;

	if (dev_to_hdlc(dev)->proto) {
	result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
	if (result != -EINVAL)
	return result;
	}

	/* Not handled by currently attached protocol (if any) */

	while (proto) {
	if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
	return result;
	proto = proto->next;
	}
	return -EINVAL;
	}

	static const struct header_ops hdlc_null_ops;

	static void hdlc_setup_dev(struct net_device *dev)
	{
	/* Re-init all variables changed by HDLC protocol drivers,
	* including ether_setup() called from hdlc_raw_eth.c.
	*/
	dev->flags = IFF_POINTOPOINT \| IFF_NOARP;
	dev->priv_flags = IFF_WAN_HDLC;
	dev->mtu = HDLC_MAX_MTU;
	dev->min_mtu = 68;
	dev->max_mtu = HDLC_MAX_MTU;
	dev->type = ARPHRD_RAWHDLC;
	dev->hard_header_len = 16;
	dev->addr_len = 0;
	dev->header_ops = &hdlc_null_ops;
	}

	static void hdlc_setup(struct net_device *dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);

	hdlc_setup_dev(dev);
	hdlc->carrier = 1;
	hdlc->open = 0;
	spin_lock_init(&hdlc->state_lock);
	}

	struct net_device alloc_hdlcdev(void priv)
	{
	struct net_device *dev;
	dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
	NET_NAME_UNKNOWN, hdlc_setup);
	if (dev)
	dev_to_hdlc(dev)->priv = priv;
	return dev;
	}

	void unregister_hdlc_device(struct net_device *dev)
	{
	rtnl_lock();
	detach_hdlc_protocol(dev);
	unregister_netdevice(dev);
	rtnl_unlock();
	}



	int attach_hdlc_protocol(struct net_device dev, struct hdlc_proto proto,
	size_t size)
	{
	int err;

	err = detach_hdlc_protocol(dev);
	if (err)
	return err;

	if (!try_module_get(proto->module))
	return -ENOSYS;

	if (size) {
	dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
	if (dev_to_hdlc(dev)->state == NULL) {
	module_put(proto->module);
	return -ENOBUFS;
	}
	}
	dev_to_hdlc(dev)->proto = proto;

	return 0;
	}


	int detach_hdlc_protocol(struct net_device *dev)
	{
	hdlc_device *hdlc = dev_to_hdlc(dev);
	int err;

	if (hdlc->proto) {
	err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
	err = notifier_to_errno(err);
	if (err) {
	netdev_err(dev, "Refused to change device type\n");
	return err;
	}

	if (hdlc->proto->detach)
	hdlc->proto->detach(dev);
	module_put(hdlc->proto->module);
	hdlc->proto = NULL;
	}
	kfree(hdlc->state);
	hdlc->state = NULL;
	hdlc_setup_dev(dev);

	return 0;
	}


	void register_hdlc_protocol(struct hdlc_proto *proto)
	{
	rtnl_lock();
	proto->next = first_proto;
	first_proto = proto;
	rtnl_unlock();
	}


	void unregister_hdlc_protocol(struct hdlc_proto *proto)
	{
	struct hdlc_proto **p;

	rtnl_lock();
	p = &first_proto;
	while (*p != proto) {
	BUG_ON(!*p);
	p = &((*p)->next);
	}
	*p = proto->next;
	rtnl_unlock();
	}



	MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
	MODULE_DESCRIPTION("HDLC support module");
	MODULE_LICENSE("GPL v2");

	EXPORT_SYMBOL(hdlc_start_xmit);
	EXPORT_SYMBOL(hdlc_open);
	EXPORT_SYMBOL(hdlc_close);
	EXPORT_SYMBOL(hdlc_ioctl);
	EXPORT_SYMBOL(alloc_hdlcdev);
	EXPORT_SYMBOL(unregister_hdlc_device);
	EXPORT_SYMBOL(register_hdlc_protocol);
	EXPORT_SYMBOL(unregister_hdlc_protocol);
	EXPORT_SYMBOL(attach_hdlc_protocol);
	EXPORT_SYMBOL(detach_hdlc_protocol);

	static struct packet_type hdlc_packet_type __read_mostly = {
	.type = cpu_to_be16(ETH_P_HDLC),
	.func = hdlc_rcv,
	};


	static struct notifier_block hdlc_notifier = {
	.notifier_call = hdlc_device_event,
	};


	static int __init hdlc_module_init(void)
	{
	int result;

	pr_info("%s\n", version);
	if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
	return result;
	dev_add_pack(&hdlc_packet_type);
	return 0;
	}



	static void __exit hdlc_module_exit(void)
	{
	dev_remove_pack(&hdlc_packet_type);
	unregister_netdevice_notifier(&hdlc_notifier);
	}


	module_init(hdlc_module_init);
	module_exit(hdlc_module_exit);