[PATCH] Modularize generic HDLC

This patch enables building of individual WAN protocol support
routines (parts of generic HDLC) as separate modules.
All protocol-private definitions are moved from hdlc.h file
to protocol drivers. User-space interface and interface
between generic HDLC and underlying low-level HDLC drivers
are unchanged.

Signed-off-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 368 insertions, 0 deletions

diff --git a/drivers/net/wan/hdlc.c b/drivers/net/wan/hdlc.c
new file mode 100644
index 0000000..db354e0
--- /dev/null
+++ b/drivers/net/wan/hdlc.c
@@ -0,0 +1,368 @@
+/*
+ * Generic HDLC support routines for Linux
+ *
+ * Copyright (C) 1999 - 2006 Krzysztof Halasa <khc@pm.waw.pl>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License
+ * as published by the Free Software Foundation.
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/poll.h>
+#include <linux/errno.h>
+#include <linux/if_arp.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/pkt_sched.h>
+#include <linux/inetdevice.h>
+#include <linux/lapb.h>
+#include <linux/rtnetlink.h>
+#include <linux/notifier.h>
+#include <linux/hdlc.h>
+
+
+static const char* version = "HDLC support module revision 1.20";
+
+#undef DEBUG_LINK
+
+static struct hdlc_proto *first_proto = NULL;
+
+
+static int hdlc_change_mtu(struct net_device *dev, int new_mtu)
+{
+	if ((new_mtu < 68) || (new_mtu > HDLC_MAX_MTU))
+		return -EINVAL;
+	dev->mtu = new_mtu;
+	return 0;
+}
+
+
+
+static struct net_device_stats *hdlc_get_stats(struct net_device *dev)
+{
+	return hdlc_stats(dev);
+}
+
+
+
+static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
+		    struct packet_type *p, struct net_device *orig_dev)
+{
+	struct hdlc_device_desc *desc = dev_to_desc(dev);
+	if (desc->netif_rx)
+		return desc->netif_rx(skb);
+
+	desc->stats.rx_dropped++; /* Shouldn't happen */
+	dev_kfree_skb(skb);
+	return NET_RX_DROP;
+}
+
+
+
+static inline void hdlc_proto_start(struct net_device *dev)
+{
+	hdlc_device *hdlc = dev_to_hdlc(dev);
+	if (hdlc->proto->start)
+		return 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)
+		return hdlc->proto->stop(dev);
+}
+
+
+
+static int hdlc_device_event(struct notifier_block *this, unsigned long event,
+			     void *ptr)
+{
+	struct net_device *dev = ptr;
+	hdlc_device *hdlc;
+	unsigned long flags;
+	int on;
+ 
+	if (dev->get_stats != hdlc_get_stats)
+		return NOTIFY_DONE; /* not an HDLC device */
+ 
+	if (event != NETDEV_CHANGE)
+		return NOTIFY_DONE; /* Only interrested 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) {
+		printk(KERN_INFO "%s: Carrier detected\n", dev->name);
+		hdlc_proto_start(dev);
+	} else {
+		printk(KERN_INFO "%s: Carrier lost\n", dev->name);
+		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) {
+		printk(KERN_INFO "%s: Carrier detected\n", dev->name);
+		hdlc_proto_start(dev);
+	} else
+		printk(KERN_INFO "%s: No carrier\n", dev->name);
+
+	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;
+}
+
+void hdlc_setup(struct net_device *dev)
+{
+	hdlc_device *hdlc = dev_to_hdlc(dev);
+
+	dev->get_stats = hdlc_get_stats;
+	dev->change_mtu = hdlc_change_mtu;
+	dev->mtu = HDLC_MAX_MTU;
+
+	dev->type = ARPHRD_RAWHDLC;
+	dev->hard_header_len = 16;
+
+	dev->flags = IFF_POINTOPOINT | IFF_NOARP;
+
+	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_desc) +
+			   sizeof(hdlc_device), "hdlc%d", hdlc_setup);
+	if (dev)
+		dev_to_hdlc(dev)->priv = priv;
+	return dev;
+}
+
+void unregister_hdlc_device(struct net_device *dev)
+{
+	rtnl_lock();
+	unregister_netdevice(dev);
+	detach_hdlc_protocol(dev);
+	rtnl_unlock();
+}
+
+
+
+int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
+			 int (*rx)(struct sk_buff *skb), size_t size)
+{
+	detach_hdlc_protocol(dev);
+
+	if (!try_module_get(proto->module))
+		return -ENOSYS;
+
+	if (size)
+		if ((dev_to_hdlc(dev)->state = kmalloc(size,
+						       GFP_KERNEL)) == NULL) {
+			printk(KERN_WARNING "Memory squeeze on"
+			       " hdlc_proto_attach()\n");
+			module_put(proto->module);
+			return -ENOBUFS;
+		}
+	dev_to_hdlc(dev)->proto = proto;
+	dev_to_desc(dev)->netif_rx = rx;
+	return 0;
+}
+
+
+void detach_hdlc_protocol(struct net_device *dev)
+{
+	hdlc_device *hdlc = dev_to_hdlc(dev);
+
+	if (hdlc->proto) {
+		if (hdlc->proto->detach)
+			hdlc->proto->detach(dev);
+		module_put(hdlc->proto->module);
+		hdlc->proto = NULL;
+	}
+	kfree(hdlc->state);
+	hdlc->state = NULL;
+}
+
+
+void register_hdlc_protocol(struct hdlc_proto *proto)
+{
+	proto->next = first_proto;
+	first_proto = proto;
+}
+
+
+void unregister_hdlc_protocol(struct hdlc_proto *proto)
+{
+	struct hdlc_proto **p = &first_proto;
+	while (*p) {
+		if (*p == proto) {
+			*p = proto->next;
+			return;
+		}
+		p = &((*p)->next);
+	}
+}
+
+
+
+MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
+MODULE_DESCRIPTION("HDLC support module");
+MODULE_LICENSE("GPL v2");
+
+EXPORT_SYMBOL(hdlc_open);
+EXPORT_SYMBOL(hdlc_close);
+EXPORT_SYMBOL(hdlc_ioctl);
+EXPORT_SYMBOL(hdlc_setup);
+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 = {
+	.type = __constant_htons(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;
+
+	printk(KERN_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);