aboutsummaryrefslogtreecommitdiff
path: root/drivers/watchdog/softdog.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/watchdog/softdog.c')
-rw-r--r--drivers/watchdog/softdog.c310
1 files changed, 310 insertions, 0 deletions
diff --git a/drivers/watchdog/softdog.c b/drivers/watchdog/softdog.c
new file mode 100644
index 00000000000..9c369490924
--- /dev/null
+++ b/drivers/watchdog/softdog.c
@@ -0,0 +1,310 @@
+/*
+ * SoftDog 0.07: A Software Watchdog Device
+ *
+ * (c) Copyright 1996 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>
+ *
+ * Software only watchdog driver. Unlike its big brother the WDT501P
+ * driver this won't always recover a failed machine.
+ *
+ * 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
+ * Modularised.
+ * Added soft_margin; use upon insmod to change the timer delay.
+ * NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
+ * minors.
+ *
+ * 19980911 Alan Cox
+ * Made SMP safe for 2.3.x
+ *
+ * 20011127 Joel Becker (jlbec@evilplan.org>
+ * Added soft_noboot; Allows testing the softdog trigger without
+ * requiring a recompile.
+ * Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
+ *
+ * 20020530 Joel Becker <joel.becker@oracle.com>
+ * Added Matt Domsch's nowayout module option.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/timer.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+
+#include <asm/uaccess.h>
+
+#define PFX "SoftDog: "
+
+#define TIMER_MARGIN 60 /* Default is 60 seconds */
+static int soft_margin = TIMER_MARGIN; /* in seconds */
+module_param(soft_margin, int, 0);
+MODULE_PARM_DESC(soft_margin, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+#ifdef ONLY_TESTING
+static int soft_noboot = 1;
+#else
+static int soft_noboot = 0;
+#endif /* ONLY_TESTING */
+
+module_param(soft_noboot, int, 0);
+MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
+
+/*
+ * Our timer
+ */
+
+static void watchdog_fire(unsigned long);
+
+static struct timer_list watchdog_ticktock =
+ TIMER_INITIALIZER(watchdog_fire, 0, 0);
+static unsigned long driver_open, orphan_timer;
+static char expect_close;
+
+
+/*
+ * If the timer expires..
+ */
+
+static void watchdog_fire(unsigned long data)
+{
+ if (test_and_clear_bit(0, &orphan_timer))
+ module_put(THIS_MODULE);
+
+ if (soft_noboot)
+ printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
+ else
+ {
+ printk(KERN_CRIT PFX "Initiating system reboot.\n");
+ emergency_restart();
+ printk(KERN_CRIT PFX "Reboot didn't ?????\n");
+ }
+}
+
+/*
+ * Softdog operations
+ */
+
+static int softdog_keepalive(void)
+{
+ mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
+ return 0;
+}
+
+static int softdog_stop(void)
+{
+ del_timer(&watchdog_ticktock);
+ return 0;
+}
+
+static int softdog_set_heartbeat(int t)
+{
+ if ((t < 0x0001) || (t > 0xFFFF))
+ return -EINVAL;
+
+ soft_margin = t;
+ return 0;
+}
+
+/*
+ * /dev/watchdog handling
+ */
+
+static int softdog_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(0, &driver_open))
+ return -EBUSY;
+ if (!test_and_clear_bit(0, &orphan_timer))
+ __module_get(THIS_MODULE);
+ /*
+ * Activate timer
+ */
+ softdog_keepalive();
+ return nonseekable_open(inode, file);
+}
+
+static int softdog_release(struct inode *inode, struct file *file)
+{
+ /*
+ * Shut off the timer.
+ * Lock it in if it's a module and we set nowayout
+ */
+ if (expect_close == 42) {
+ softdog_stop();
+ module_put(THIS_MODULE);
+ } else {
+ printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
+ set_bit(0, &orphan_timer);
+ softdog_keepalive();
+ }
+ clear_bit(0, &driver_open);
+ expect_close = 0;
+ return 0;
+}
+
+static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
+{
+ /*
+ * Refresh the timer.
+ */
+ if(len) {
+ if (!nowayout) {
+ size_t i;
+
+ /* In case it was set long ago */
+ expect_close = 0;
+
+ for (i = 0; i != len; i++) {
+ char c;
+
+ if (get_user(c, data + i))
+ return -EFAULT;
+ if (c == 'V')
+ expect_close = 42;
+ }
+ }
+ softdog_keepalive();
+ }
+ return len;
+}
+
+static int softdog_ioctl(struct inode *inode, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ void __user *argp = (void __user *)arg;
+ int __user *p = argp;
+ int new_margin;
+ static struct watchdog_info ident = {
+ .options = WDIOF_SETTIMEOUT |
+ WDIOF_KEEPALIVEPING |
+ WDIOF_MAGICCLOSE,
+ .firmware_version = 0,
+ .identity = "Software Watchdog",
+ };
+ switch (cmd) {
+ default:
+ return -ENOTTY;
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp, &ident,
+ sizeof(ident)) ? -EFAULT : 0;
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ return put_user(0, p);
+ case WDIOC_KEEPALIVE:
+ softdog_keepalive();
+ return 0;
+ case WDIOC_SETTIMEOUT:
+ if (get_user(new_margin, p))
+ return -EFAULT;
+ if (softdog_set_heartbeat(new_margin))
+ return -EINVAL;
+ softdog_keepalive();
+ /* Fall */
+ case WDIOC_GETTIMEOUT:
+ return put_user(soft_margin, p);
+ }
+}
+
+/*
+ * Notifier for system down
+ */
+
+static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
+ void *unused)
+{
+ if(code==SYS_DOWN || code==SYS_HALT) {
+ /* Turn the WDT off */
+ softdog_stop();
+ }
+ return NOTIFY_DONE;
+}
+
+/*
+ * Kernel Interfaces
+ */
+
+static const struct file_operations softdog_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = softdog_write,
+ .ioctl = softdog_ioctl,
+ .open = softdog_open,
+ .release = softdog_release,
+};
+
+static struct miscdevice softdog_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &softdog_fops,
+};
+
+static struct notifier_block softdog_notifier = {
+ .notifier_call = softdog_notify_sys,
+};
+
+static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
+
+static int __init watchdog_init(void)
+{
+ int ret;
+
+ /* Check that the soft_margin value is within it's range ; if not reset to the default */
+ if (softdog_set_heartbeat(soft_margin)) {
+ softdog_set_heartbeat(TIMER_MARGIN);
+ printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n",
+ TIMER_MARGIN);
+ }
+
+ ret = register_reboot_notifier(&softdog_notifier);
+ if (ret) {
+ printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
+ ret);
+ return ret;
+ }
+
+ ret = misc_register(&softdog_miscdev);
+ if (ret) {
+ printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
+ WATCHDOG_MINOR, ret);
+ unregister_reboot_notifier(&softdog_notifier);
+ return ret;
+ }
+
+ printk(banner, soft_noboot, soft_margin, nowayout);
+
+ return 0;
+}
+
+static void __exit watchdog_exit(void)
+{
+ misc_deregister(&softdog_miscdev);
+ unregister_reboot_notifier(&softdog_notifier);
+}
+
+module_init(watchdog_init);
+module_exit(watchdog_exit);
+
+MODULE_AUTHOR("Alan Cox");
+MODULE_DESCRIPTION("Software Watchdog Device Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);