[WATCHDOG] Add several new watchdog drivers from 2.4

drivers/char/watchdog/Kconfig

@@ -283,4 +283,24 @@ config MACHZ_WDT
 	  The module is called machzwd.o.  If you want to compile it as a
 	  module, say M here and read <file:Documentation/modules.txt>.
 
+config W83877F_WDT
+	tristate "W83877F Computer Watchdog"
+	depends on WATCHDOG
+
+config SC520_WDT
+	tristate "AMD Elan SC520 processor Watchdog"
+	depends on WATCHDOG
+
+config ALIM7101_WDT
+	tristate "ALi M7101 PMU Computer Watchdog"
+	depends on WATCHDOG
+
+config SC1200_WDT
+	tristate "National Semiconductor PC87307/PC97307 (ala SC1200) Watchdog"
+	depends on WATCHDOG
+
+config WAFER_WDT
+	tristate "ICP Wafer 5823 Single Board Computer Watchdog"
+	depends on WATCHDOG
+
 endmenu

drivers/char/watchdog/Makefile

@@ -23,3 +23,8 @@ obj-$(CONFIG_MACHZ_WDT) += machzwd.o
 obj-$(CONFIG_SH_WDT) += shwdt.o
 obj-$(CONFIG_EUROTECH_WDT) += eurotechwdt.o
 obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
+obj-$(CONFIG_W83877F_WDT) += w83877f_wdt.o
+obj-$(CONFIG_SC520_WDT) += sc520_wdt.o
+obj-$(CONFIG_ALIM7101_WDT) += alim7101_wdt.o
+obj-$(CONFIG_SC1200_WDT) += sc1200wdt.o
+obj-$(CONFIG_WAFER_WDT) += wafer5823wdt.o

drivers/char/watchdog/alim7101_wdt.c

+/*
+ *	ALi M7101 PMU Computer Watchdog Timer driver for Linux 2.4.x
+ *
+ *	Based on w83877f_wdt.c by Scott Jennings <management@oro.net>
+ *	and the Cobalt kernel WDT timer driver by Tim Hockin
+ *	                                      <thockin@cobaltnet.com>
+ *
+ *	(c)2002 Steve Hill <steve@navaho.co.uk>
+ * 
+ *  Theory of operation:
+ *  A Watchdog Timer (WDT) is a hardware circuit that can 
+ *  reset the computer system in case of a software fault.
+ *  You probably knew that already.
+ *
+ *  Usually a userspace daemon will notify the kernel WDT driver
+ *  via the /proc/watchdog special device file that userspace is
+ *  still alive, at regular intervals.  When such a notification
+ *  occurs, the driver will usually tell the hardware watchdog
+ *  that everything is in order, and that the watchdog should wait
+ *  for yet another little while to reset the system.
+ *  If userspace fails (RAM error, kernel bug, whatever), the
+ *  notifications cease to occur, and the hardware watchdog will
+ *  reset the system (causing a reboot) after the timeout occurs.
+ *
+ *  This WDT driver is different from most other Linux WDT
+ *  drivers in that the driver will ping the watchdog by itself,
+ *  because this particular WDT has a very short timeout (1.6
+ *  seconds) and it would be insane to count on any userspace
+ *  daemon always getting scheduled within that time frame.
+ */
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/sched.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/slab.h>
+#include <linux/ioport.h>
+#include <linux/fcntl.h>
+#include <linux/smp_lock.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+
+#define OUR_NAME "alim7101_wdt"
+
+#define WDT_ENABLE 0x9C
+#define WDT_DISABLE 0x8C
+
+#define ALI_7101_WDT    0x92
+#define ALI_WDT_ARM     0x01
+
+/*
+ * We're going to use a 1 second timeout.
+ * If we reset the watchdog every ~250ms we should be safe.  */
+
+#define WDT_INTERVAL (HZ/4+1)
+
+/*
+ * We must not require too good response from the userspace daemon.
+ * Here we require the userspace daemon to send us a heartbeat
+ * char to /dev/watchdog every 30 seconds.
+ */
+
+#define WDT_HEARTBEAT (HZ * 30)
+
+static void wdt_timer_ping(unsigned long);
+static struct timer_list timer;
+static unsigned long next_heartbeat;
+static unsigned long wdt_is_open;
+static int wdt_expect_close;
+static struct pci_dev *alim7101_pmu;
+
+/*
+ *	Whack the dog
+ */
+
+static void wdt_timer_ping(unsigned long data)
+{
+	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
+	 * we agree to ping the WDT 
+	 */
+	char	tmp;
+
+	if(time_before(jiffies, next_heartbeat)) 
+	{
+		/* Ping the WDT (this is actually a disarm/arm sequence) */
+		pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
+		pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
+		pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp | ALI_WDT_ARM));
+	} else {
+		printk(OUR_NAME ": Heartbeat lost! Will not ping the watchdog\n");
+	}
+	/* Re-set the timer interval */
+	timer.expires = jiffies + WDT_INTERVAL;
+	add_timer(&timer);
+}
+
+/* 
+ * Utility routines
+ */
+
+static void wdt_change(int writeval)
+{
+	char	tmp;
+
+	pci_read_config_byte(alim7101_pmu, 0x92, &tmp);
+	if (writeval == WDT_ENABLE)
+		pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp | ALI_WDT_ARM));
+	else
+		pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, (tmp & ~ALI_WDT_ARM));
+}
+
+static void wdt_startup(void)
+{
+	next_heartbeat = jiffies + WDT_HEARTBEAT;
+
+	/* We must enable before we kick off the timer in case the timer
+	   occurs as we ping it */
+
+	wdt_change(WDT_ENABLE);
+
+	/* Start the timer */
+	timer.expires = jiffies + WDT_INTERVAL;	
+	add_timer(&timer);
+
+
+	printk(OUR_NAME ": Watchdog timer is now enabled.\n");  
+}
+
+static void wdt_turnoff(void)
+{
+	/* Stop the timer */
+	del_timer_sync(&timer);
+	wdt_change(WDT_DISABLE);
+	printk(OUR_NAME ": Watchdog timer is now disabled...\n");
+}
+
+/*
+ * /dev/watchdog handling
+ */
+
+static ssize_t fop_write(struct file * file, const char * buf, size_t count, loff_t * ppos)
+{
+	/* We can't seek */
+	if(ppos != &file->f_pos)
+		return -ESPIPE;
+
+	/* See if we got the magic character */
+	if(count) 
+	{
+		size_t ofs;
+
+		/* note: just in case someone wrote the magic character
+		 * five months ago... */
+		wdt_expect_close = 0;
+
+		/* now scan */
+		for(ofs = 0; ofs != count; ofs++)
+		{
+			char c;
+			if(get_user(c, buf+ofs))
+				return -EFAULT;
+			if(c == 'V')
+				wdt_expect_close = 1;
+		}
+		/* someone wrote to us, we should restart timer */
+		next_heartbeat = jiffies + WDT_HEARTBEAT;
+		return 1;
+	};
+	return 0;
+}
+
+static ssize_t fop_read(struct file * file, char * buf, size_t count, loff_t * ppos)
+{
+	/* No can do */
+	return -EINVAL;
+}
+
+static int fop_open(struct inode * inode, struct file * file)
+{
+	/* Just in case we're already talking to someone... */
+	if(test_and_set_bit(0, &wdt_is_open))
+		return -EBUSY;
+	/* Good, fire up the show */
+	wdt_startup();
+	return 0;
+}
+
+static int fop_close(struct inode * inode, struct file * file)
+{
+#ifdef CONFIG_WDT_NOWAYOUT
+	if(wdt_expect_close)
+		wdt_turnoff();
+	else {
+		printk(OUR_NAME ": device file closed unexpectedly. Will not stop the WDT!\n");
+	}
+#else
+	wdt_turnoff();
+#endif
+	clear_bit(0, &wdt_is_open);
+	return 0;
+}
+
+static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
+{
+	static struct watchdog_info ident=
+	{
+		0,
+		1,
+		"ALiM7101"
+	};
+	
+	switch(cmd)
+	{
+		case WDIOC_GETSUPPORT:
+			return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))?-EFAULT:0;
+		case WDIOC_KEEPALIVE:
+			next_heartbeat = jiffies + WDT_HEARTBEAT;
+			return 0;
+		default:
+			return -ENOTTY;
+	}
+}
+
+static struct file_operations wdt_fops = {
+	.owner=		THIS_MODULE,
+	.llseek=		no_llseek,
+	.read=		fop_read,
+	.write=		fop_write,
+	.open=		fop_open,
+	.release=	fop_close,
+	.ioctl=		fop_ioctl
+};
+
+static struct miscdevice wdt_miscdev = {
+	.minor=WATCHDOG_MINOR,
+	.name="watchdog",
+	.fops=&wdt_fops
+};
+
+/*
+ *	Notifier for system down
+ */
+
+static int wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
+{
+	if (code==SYS_DOWN || code==SYS_HALT) wdt_turnoff();
+	if (code==SYS_RESTART) {
+		/*
+		 * Cobalt devices have no way of rebooting themselves other than
+		 * getting the watchdog to pull reset, so we restart the watchdog on
+		 * reboot with no heartbeat
+		 */
+		wdt_change(WDT_ENABLE);
+		printk(OUR_NAME ": Watchdog timer is now enabled with no heartbeat - should reboot in ~1 second.\n");
+	};
+	return NOTIFY_DONE;
+}
+ 
+/*
+ *	The WDT needs to learn about soft shutdowns in order to
+ *	turn the timebomb registers off. 
+ */
+ 
+static struct notifier_block wdt_notifier=
+{
+	wdt_notify_sys,
+	0,
+	0
+};
+
+static void __exit alim7101_wdt_unload(void)
+{
+	wdt_turnoff();
+	/* Deregister */
+	misc_deregister(&wdt_miscdev);
+	unregister_reboot_notifier(&wdt_notifier);
+}
+
+static int __init alim7101_wdt_init(void)
+{
+	int rc = -EBUSY;
+	struct pci_dev *ali1543_south;
+	char tmp;
+
+	printk(KERN_INFO OUR_NAME ": Steve Hill <steve@navaho.co.uk>.\n");
+	alim7101_pmu = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M7101,NULL);
+	if (!alim7101_pmu) {
+		printk(KERN_INFO OUR_NAME ": ALi M7101 PMU not present - WDT not set\n");
+		return -EBUSY;
+	};
+	
+	/* Set the WDT in the PMU to 1 second */
+	pci_write_config_byte(alim7101_pmu, ALI_7101_WDT, 0x02);
+
+	ali1543_south = pci_find_device(PCI_VENDOR_ID_AL, PCI_DEVICE_ID_AL_M1533, NULL);
+	if (!ali1543_south) {
+		printk(KERN_INFO OUR_NAME ": ALi 1543 South-Bridge not present - WDT not set\n");
+		return -EBUSY;
+	};
+	pci_read_config_byte(ali1543_south, 0x5e, &tmp);
+	if ((tmp & 0x1e) != 0x12) {
+		printk(KERN_INFO OUR_NAME ": ALi 1543 South-Bridge does not have the correct revision number (???1001?) - WDT not set\n");
+		return -EBUSY;
+	};
+
+	init_timer(&timer);
+	timer.function = wdt_timer_ping;
+	timer.data = 1;
+		
+	rc = misc_register(&wdt_miscdev);
+	if (rc)
+		return rc;
+
+	rc = register_reboot_notifier(&wdt_notifier);
+	if (rc) {
+		misc_deregister(&wdt_miscdev);
+		return rc;
+	};
+	
+	printk(KERN_INFO OUR_NAME ": WDT driver for ALi M7101 initialised.\n");
+	return 0;
+}
+
+module_init(alim7101_wdt_init);
+module_exit(alim7101_wdt_unload);
+
+EXPORT_NO_SYMBOLS;
+MODULE_AUTHOR("Steve Hill");
+MODULE_LICENSE("GPL");

drivers/char/watchdog/indydog.c

+/*
+ *	IndyDog	0.2	A Hardware Watchdog Device for SGI IP22
+ *
+ *	(c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, All Rights Reserved.
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *	
+ *	based on softdog.c by Alan Cox <alan@redhat.com>
+ */
+ 
+#include <linux/module.h>
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/smp_lock.h>
+#include <linux/init.h>
+#include <asm/uaccess.h>
+#include <asm/sgi/sgimc.h>
+
+static unsigned long indydog_alive;
+static struct sgimc_misc_ctrl *mcmisc_regs; 
+
+static void indydog_ping()
+{
+	mcmisc_regs->watchdogt = 0;
+}
+
+
+/*
+ *	Allow only one person to hold it open
+ */
+
+static int indydog_open(struct inode *inode, struct file *file)
+{
+	u32 mc_ctrl0;
+	
+	if( test_and_set_bit(0,&indydog_alive) )
+		return -EBUSY;
+#ifdef CONFIG_WATCHDOG_NOWAYOUT
+	MOD_INC_USE_COUNT;
+#endif
+	/*
+	 *	Activate timer
+	 */
+	mcmisc_regs = (struct sgimc_misc_ctrl *)(KSEG1+0x1fa00000);
+
+	mc_ctrl0 = mcmisc_regs->cpuctrl0 | SGIMC_CCTRL0_WDOG;
+	mcmisc_regs->cpuctrl0 = mc_ctrl0;
+	indydog_ping();
+			
+	printk("Started watchdog timer.\n");
+	return 0;
+}
+
+static int indydog_release(struct inode *inode, struct file *file)
+{
+	/*
+	 *	Shut off the timer.
+	 * 	Lock it in if it's a module and we defined ...NOWAYOUT
+	 */
+#ifndef CONFIG_WATCHDOG_NOWAYOUT
+	{
+	u32 mc_ctrl0 = mcmisc_regs->cpuctrl0; 
+	mc_ctrl0 &= ~SGIMC_CCTRL0_WDOG;
+	mcmisc_regs->cpuctrl0 = mc_ctrl0;
+	printk("Stopped watchdog timer.\n");
+	}
+#endif
+	clear_bit(0,&indydog_alive);
+	return 0;
+}
+
+static ssize_t indydog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
+{
+	/*  Can't seek (pwrite) on this device  */
+	if (ppos != &file->f_pos)
+		return -ESPIPE;
+
+	/*
+	 *	Refresh the timer.
+	 */
+	if(len) {
+		indydog_ping();
+		return 1;
+	}
+	return 0;
+}
+
+static int indydog_ioctl(struct inode *inode, struct file *file,
+	unsigned int cmd, unsigned long arg)
+{
+	static struct watchdog_info ident = {
+		identity: "Hardware Watchdog for SGI IP22",
+	};
+	switch (cmd) {
+		default:
+			return -ENOIOCTLCMD;
+		case WDIOC_GETSUPPORT:
+			if(copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
+				return -EFAULT;
+			return 0;
+		case WDIOC_GETSTATUS:
+		case WDIOC_GETBOOTSTATUS:
+			return put_user(0,(int *)arg);
+		case WDIOC_KEEPALIVE:
+			indydog_ping();
+			return 0;
+	}
+}
+
+static struct file_operations indydog_fops = {
+	.owner	= THIS_MODULE,
+	.write	= indydog_write,
+	.ioctl	= indydog_ioctl,
+	.open	= indydog_open,
+	.release= indydog_release,
+};
+
+static struct miscdevice indydog_miscdev = {
+	.minor	= WATCHDOG_MINOR,
+	.name	= "watchdog",
+	.fops	= &indydog_fops,
+};
+
+static const char banner[] __initdata = KERN_INFO "Hardware Watchdog Timer for SGI IP22: 0.2\n";
+
+static int __init watchdog_init(void)
+{
+	int ret;
+
+	ret = misc_register(&indydog_miscdev);
+
+	if (ret)
+		return ret;
+
+	printk(banner);
+
+	return 0;
+}
+
+static void __exit watchdog_exit(void)
+{
+	misc_deregister(&indydog_miscdev);
+}
+
+module_init(watchdog_init);
+module_exit(watchdog_exit);
+MODULE_LICENSE("GPL");

drivers/char/watchdog/sc520_wdt.c

+/*
+ *	AMD Elan SC520 processor Watchdog Timer driver for Linux 2.4.x
+ *
+ *      Based on acquirewdt.c by Alan Cox,
+ *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@ostenfeld.dk>
+ *     
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *	
+ *	The authors do NOT admit liability nor provide warranty for 
+ *	any of this software. This material is provided "AS-IS" in 
+ *      the hope that it may be useful for others.
+ *
+ *	(c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
+ *           9/27 - 2001      [Initial release]
+ *	
+ *	Additional fixes Alan Cox
+ *	-	Fixed formatting
+ *	-	Removed debug printks
+ *	-	Fixed SMP built kernel deadlock
+ *	-	Switched to private locks not lock_kernel
+ *	-	Used ioremap/writew/readw
+ *	-	Added NOWAYOUT support
+ *
+ *  Theory of operation:
+ *  A Watchdog Timer (WDT) is a hardware circuit that can 
+ *  reset the computer system in case of a software fault.
+ *  You probably knew that already.
+ *
+ *  Usually a userspace daemon will notify the kernel WDT driver
+ *  via the /proc/watchdog special device file that userspace is
+ *  still alive, at regular intervals.  When such a notification
+ *  occurs, the driver will usually tell the hardware watchdog
+ *  that everything is in order, and that the watchdog should wait
+ *  for yet another little while to reset the system.
+ *  If userspace fails (RAM error, kernel bug, whatever), the
+ *  notifications cease to occur, and the hardware watchdog will
+ *  reset the system (causing a reboot) after the timeout occurs.
+ *
+ *  This WDT driver is different from most other Linux WDT
+ *  drivers in that the driver will ping the watchdog by itself,
+ *  because this particular WDT has a very short timeout (1.6
+ *  seconds) and it would be insane to count on any userspace
+ *  daemon always getting scheduled within that time frame.
+ *
+ *  This driver uses memory mapped IO, and spinlock.
+ */
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/sched.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/slab.h>
+#include <linux/ioport.h>
+#include <linux/fcntl.h>
+#include <linux/smp_lock.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+
+/*
+ * The SC520 can timeout anywhere from 492us to 32.21s.
+ * If we reset the watchdog every ~250ms we should be safe.
+ */
+
+#define WDT_INTERVAL (HZ/4+1)
+
+/*
+ * We must not require too good response from the userspace daemon.
+ * Here we require the userspace daemon to send us a heartbeat
+ * char to /dev/watchdog every 30 seconds.
+ */
+
+#define WDT_HEARTBEAT (HZ * 30)
+
+/*
+ * AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
+ *
+ *   0: 492us    2: 1.01s    4: 4.03s   6: 16.22s
+ *   1: 503ms    3: 2.01s    5: 8.05s   7: 32.21s
+ */
+
+#define TIMEOUT_EXPONENT ( 1 << 3 )  /* 0x08 = 2.01s */
+
+/* #define MMCR_BASE_DEFAULT 0xfffef000 */
+#define MMCR_BASE_DEFAULT ((__u16 *)0xffffe)
+#define OFFS_WDTMRCTL ((unsigned int)0xcb0)
+#define WDT_ENB 0x8000		/* [15] Watchdog Timer Enable */
+#define WDT_WRST_ENB 0x4000	/* [14] Watchdog Timer Reset Enable */
+
+#define OUR_NAME "sc520_wdt"
+
+#define WRT_DOG(data) *wdtmrctl=data
+
+static __u16 *wdtmrctl;
+
+static void wdt_timer_ping(unsigned long);
+static struct timer_list timer;
+static unsigned long next_heartbeat;
+static unsigned long wdt_is_open;
+static int wdt_expect_close;
+
+static spinlock_t wdt_spinlock;
+/*
+ *	Whack the dog
+ */
+
+static void wdt_timer_ping(unsigned long data)
+{
+	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
+	 * we agree to ping the WDT 
+	 */
+	if(time_before(jiffies, next_heartbeat)) 
+	{
+		/* Ping the WDT */
+		spin_lock(&wdt_spinlock);
+		writew(0xAAAA, wdtmrctl);
+		writew(0x5555, wdtmrctl);
+		spin_unlock(&wdt_spinlock);
+
+		/* Re-set the timer interval */
+		timer.expires = jiffies + WDT_INTERVAL;
+		add_timer(&timer);
+	} else {
+		printk(OUR_NAME ": Heartbeat lost! Will not ping the watchdog\n");
+	}
+}
+
+/* 
+ * Utility routines
+ */
+
+static void wdt_config(int writeval)
+{
+	__u16 dummy;
+	unsigned long flags;
+
+	/* buy some time (ping) */
+	spin_lock_irqsave(&wdt_spinlock, flags);
+	dummy=readw(wdtmrctl);  /* ensure write synchronization */
+	writew(0xAAAA, wdtmrctl);
+	writew(0x5555, wdtmrctl);
+	/* make WDT configuration register writable one time */
+	writew(0x3333, wdtmrctl);
+	writew(0xCCCC, wdtmrctl);
+	/* write WDT configuration register */
+	writew(writeval, wdtmrctl);
+	spin_unlock_irqrestore(&wdt_spinlock, flags);
+}
+
+static void wdt_startup(void)
+{
+	next_heartbeat = jiffies + WDT_HEARTBEAT;
+
+	/* Start the timer */
+	timer.expires = jiffies + WDT_INTERVAL;	
+	add_timer(&timer);
+
+	wdt_config(WDT_ENB | WDT_WRST_ENB | TIMEOUT_EXPONENT);
+	printk(OUR_NAME ": Watchdog timer is now enabled.\n");  
+}
+
+static void wdt_turnoff(void)
+{
+#ifndef CONFIG_WATCHDOG_NOWAYOUT
+	/* Stop the timer */
+	del_timer(&timer);
+	wdt_config(0);
+	printk(OUR_NAME ": Watchdog timer is now disabled...\n");
+#endif
+}
+
+
+/*
+ * /dev/watchdog handling
+ */
+
+static ssize_t fop_write(struct file * file, const char * buf, size_t count, loff_t * ppos)
+{
+	/* We can't seek */
+	if(ppos != &file->f_pos)
+		return -ESPIPE;
+
+	/* See if we got the magic character */
+	if(count) 
+	{
+		size_t ofs;
+
+		/* note: just in case someone wrote the magic character
+		 * five months ago... */
+		wdt_expect_close = 0;
+
+		/* now scan */
+		for(ofs = 0; ofs != count; ofs++) {
+			char c;
+			if (get_user(c, buf + ofs))
+				return -EFAULT;
+			if(c == 'V')
+				wdt_expect_close = 1;
+		}
+
+		/* Well, anyhow someone wrote to us, we should return that favour */
+		next_heartbeat = jiffies + WDT_HEARTBEAT;
+		return 1;
+	}
+	return 0;
+}
+
+static int fop_open(struct inode * inode, struct file * file)
+{
+	switch(minor(inode->i_rdev)) 
+	{
+		case WATCHDOG_MINOR:
+			/* Just in case we're already talking to someone... */
+			if(test_and_set_bit(0, &wdt_is_open))
+				return -EBUSY;
+			/* Good, fire up the show */
+			wdt_startup();
+#ifdef CONFIG_WATCHDOG_NOWAYOUT
+			MOD_INC_USE_COUNT;
+#endif	
+			return 0;
+		default:
+			return -ENODEV;
+	}
+}
+
+static int fop_close(struct inode * inode, struct file * file)
+{
+	if(minor(inode->i_rdev) == WATCHDOG_MINOR) 
+	{
+		if(wdt_expect_close)
+			wdt_turnoff();
+		else {
+			del_timer(&timer);
+			printk(OUR_NAME ": device file closed unexpectedly. Will not stop the WDT!\n");
+		}
+	}
+	clear_bit(0, &wdt_is_open);
+	return 0;
+}
+
+static long long fop_llseek(struct file *file, long long offset, int origin)
+{
+	return -ESPIPE;
+}
+
+static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+	unsigned long arg)
+{
+	static struct watchdog_info ident=
+	{
+		0,
+		1,
+		"SC520"
+	};
+	
+	switch(cmd)
+	{
+		default:
+			return -ENOIOCTLCMD;
+		case WDIOC_GETSUPPORT:
+			return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident))?-EFAULT:0;
+		case WDIOC_KEEPALIVE:
+			next_heartbeat = jiffies + WDT_HEARTBEAT;
+			return 0;
+	}
+}
+
+static struct file_operations wdt_fops = {
+	owner:		THIS_MODULE,
+	llseek:		fop_llseek,
+	write:		fop_write,
+	open:		fop_open,
+	release:	fop_close,
+	ioctl:		fop_ioctl
+};
+
+static struct miscdevice wdt_miscdev = {
+	WATCHDOG_MINOR,
+	"watchdog",
+	&wdt_fops
+};
+
+/*
+ *	Notifier for system down
+ */
+
+static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
+	void *unused)
+{
+	if(code==SYS_DOWN || code==SYS_HALT) 
+		wdt_turnoff();
+	return NOTIFY_DONE;
+}
+ 
+/*
+ *	The WDT needs to learn about soft shutdowns in order to
+ *	turn the timebomb registers off. 
+ */
+ 
+static struct notifier_block wdt_notifier=
+{
+	wdt_notify_sys,
+	0,
+	0
+};
+
+static void __exit sc520_wdt_unload(void)
+{
+	wdt_turnoff();
+
+	/* Deregister */
+	misc_deregister(&wdt_miscdev);
+	iounmap(wdtmrctl);
+	unregister_reboot_notifier(&wdt_notifier);
+}
+
+static int __init sc520_wdt_init(void)
+{
+	int rc = -EBUSY;
+	unsigned long cbar;
+
+	spin_lock_init(&wdt_spinlock);
+
+	init_timer(&timer);
+	timer.function = wdt_timer_ping;
+	timer.data = 0;
+
+	rc = misc_register(&wdt_miscdev);
+	if (rc)
+		goto err_out_region2;
+
+	rc = register_reboot_notifier(&wdt_notifier);
+	if (rc)
+		goto err_out_miscdev;
+
+	/* get the Base Address Register */
+	cbar = inl_p(0xfffc);
+	printk(OUR_NAME ": CBAR: 0x%08lx\n", cbar);
+	/* check if MMCR aliasing bit is set */
+	if (cbar & 0x80000000) {
+		printk(OUR_NAME ": MMCR Aliasing enabled.\n");
+		wdtmrctl = (__u16 *)(cbar & 0x3fffffff);
+	} else {
+		printk(OUR_NAME "!!! WARNING !!!\n"
+		  "\t MMCR Aliasing found NOT enabled!\n"
+		  "\t Using default value of: %p\n"
+		  "\t This has not been tested!\n"
+		  "\t Please email Scott Jennings <smj@oro.net>\n"
+		  "\t  and Bill Jennings <bj@oro.net> if it works!\n"
+		  , MMCR_BASE_DEFAULT
+		  );
+	  wdtmrctl = MMCR_BASE_DEFAULT;
+	}
+
+	wdtmrctl = (__u16 *)((char *)wdtmrctl + OFFS_WDTMRCTL);
+	wdtmrctl = ioremap((unsigned long)wdtmrctl, 2);
+	printk(KERN_INFO OUR_NAME ": WDT driver for SC520 initialised.\n");
+
+	return 0;
+
+err_out_miscdev:
+	misc_deregister(&wdt_miscdev);
+err_out_region2:
+	return rc;
+}
+
+module_init(sc520_wdt_init);
+module_exit(sc520_wdt_unload);
+
+MODULE_AUTHOR("Scott and Bill Jennings");
+MODULE_DESCRIPTION("Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
+MODULE_LICENSE("GPL");
+EXPORT_NO_SYMBOLS;

drivers/char/watchdog/wafer5823wdt.c

+/*
+ *	ICP Wafer 5823 Single Board Computer WDT driver for Linux 2.4.x
+ *      http://www.icpamerica.com/wafer_5823.php
+ *      May also work on other similar models
+ *
+ *	(c) Copyright 2002 Justin Cormack <justin@street-vision.com>
+ *
+ *      Release 0.02
+ *
+ *	Based on advantechwdt.c which is based on wdt.c.
+ *	Original copyright messages:
+ *
+ *	(c) Copyright 1996-1997 Alan Cox <alan@redhat.com>, All Rights Reserved.
+ *				http://www.redhat.com
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ *	
+ *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide 
+ *	warranty for any of this software. This material is provided 
+ *	"AS-IS" and at no charge.	
+ *
+ *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/ioport.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/spinlock.h>
+
+static unsigned long wafwdt_is_open;
+static spinlock_t wafwdt_lock;
+
+/*
+ *	You must set these - there is no sane way to probe for this board.
+ *
+ *      To enable, write the timeout value in seconds (1 to 255) to I/O
+ *      port WDT_START, then read the port to start the watchdog. To pat
+ *      the dog, read port WDT_STOP to stop the timer, then read WDT_START
+ *      to restart it again.
+ */
+
+#define WDT_START 0x443
+#define WDT_STOP 0x843
+
+#define WD_TIMO 60		/* 1 minute */
+static int wd_margin = WD_TIMO;
+
+static void wafwdt_ping(void)
+{
+	/* pat watchdog */
+        spin_lock(&wafwdt_lock);
+	inb_p(WDT_STOP);
+	inb_p(WDT_START);
+        spin_unlock(&wafwdt_lock);
+}
+
+static void wafwdt_start(void)
+{
+	/* start up watchdog */
+	outb_p(wd_margin, WDT_START);
+	inb_p(WDT_START);
+}
+
+static void
+wafwdt_stop(void)
+{
+	/* stop watchdog */
+	inb_p(WDT_STOP);
+}
+
+static ssize_t wafwdt_write(struct file *file, const char *buf, size_t count, loff_t * ppos)
+{
+	/*  Can't seek (pwrite) on this device  */
+	if (ppos != &file->f_pos)
+		return -ESPIPE;
+
+	if (count) {
+		wafwdt_ping();
+		return 1;
+	}
+	return 0;
+}
+
+static int wafwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+	     unsigned long arg)
+{
+	int new_margin;
+	static struct watchdog_info ident = {
+		WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+		1, "Wafer 5823 WDT"
+	};
+	int one=1;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		if (copy_to_user
+		    ((struct watchdog_info *) arg, &ident, sizeof (ident)))
+			return -EFAULT;
+		break;
+
+	case WDIOC_GETSTATUS:
+		if (copy_to_user((int *) arg, &one, sizeof (int)))
+			return -EFAULT;
+		break;
+
+	case WDIOC_KEEPALIVE:
+		wafwdt_ping();
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_margin, (int *)arg))
+			return -EFAULT;
+		if ((new_margin < 1) || (new_margin > 255))
+			return -EINVAL;
+		wd_margin = new_margin;
+		wafwdt_stop();
+		wafwdt_start();
+		/* Fall */
+	case WDIOC_GETTIMEOUT:
+		return put_user(wd_margin, (int *)arg);
+
+	default:
+		return -ENOTTY;
+	}
+	return 0;
+}
+
+static int wafwdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(0, &wafwdt_is_open))
+		return -EBUSY;
+	wafwdt_start();
+	return 0;
+}
+
+static int
+wafwdt_close(struct inode *inode, struct file *file)
+{
+	clear_bit(0, &wafwdt_is_open);
+#ifndef CONFIG_WATCHDOG_NOWAYOUT
+        wafwdt_stop();
+#endif
+	return 0;
+}
+
+/*
+ *	Notifier for system down
+ */
+
+static int wafwdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
+{
+	if (code == SYS_DOWN || code == SYS_HALT) {
+		/* Turn the WDT off */
+		wafwdt_stop();
+	}
+	return NOTIFY_DONE;
+}
+
+/*
+ *	Kernel Interfaces
+ */
+
+static struct file_operations wafwdt_fops = {
+	owner:THIS_MODULE,
+	write:wafwdt_write,
+	ioctl:wafwdt_ioctl,
+	open:wafwdt_open,
+	release:wafwdt_close,
+};
+
+static struct miscdevice wafwdt_miscdev = {
+	WATCHDOG_MINOR,
+	"watchdog",
+	&wafwdt_fops
+};
+
+/*
+ *	The WDT needs to learn about soft shutdowns in order to
+ *	turn the timebomb registers off. 
+ */
+
+static struct notifier_block wafwdt_notifier = {
+	wafwdt_notify_sys,
+	NULL,
+	0
+};
+
+static int __init wafwdt_init(void)
+{
+	printk(KERN_INFO "WDT driver for Wafer 5823 single board computer initialising.\n");
+
+	spin_lock_init(&wafwdt_lock);
+	if(!request_region(WDT_STOP, 1, "Wafer 5823 WDT"))
+		goto error;
+	if(!request_region(WDT_START, 1, "Wafer 5823 WDT"))
+		goto error2;
+	if(misc_register(&wafwdt_miscdev)<0)
+		goto error3;
+	register_reboot_notifier(&wafwdt_notifier);
+	return 0;
+error3:
+	release_region(WDT_START, 1);
+error2:
+	release_region(WDT_STOP, 1);
+error:
+	return -ENODEV;
+}
+
+static void __exit wafwdt_exit(void)
+{
+	misc_deregister(&wafwdt_miscdev);
+	unregister_reboot_notifier(&wafwdt_notifier);
+	release_region(WDT_STOP, 1);
+	release_region(WDT_START, 1);
+}
+
+module_init(wafwdt_init);
+module_exit(wafwdt_exit);
+
+MODULE_AUTHOR("Justin Cormack");
+MODULE_LICENSE("GPL");
+EXPORT_NO_SYMBOLS;
+
+/* end of wafer5823wdt.c */