patch-2.4.19 linux-2.4.19/drivers/char/alim7101_wdt.c

• Lines: 336
• Date: Fri Aug 2 17:39:43 2002
• Orig file: linux-2.4.18/drivers/char/alim7101_wdt.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.18/drivers/char/alim7101_wdt.c linux-2.4.19/drivers/char/alim7101_wdt.c
@@ -0,0 +1,335 @@
+/*
+ *	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++)
+			if(buf[ofs] == '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 = {
+	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();
+	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");