patch-2.4.7 linux/drivers/char/w83877f_wdt.c
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- Lines: 348
- Date:
Wed Jul 4 14:41:33 2001
- Orig file:
v2.4.6/linux/drivers/char/w83877f_wdt.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.4.6/linux/drivers/char/w83877f_wdt.c linux/drivers/char/w83877f_wdt.c
@@ -0,0 +1,347 @@
+/*
+ * W83877F Computer 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 <management@oro.net>
+ *
+ * 4/19 - 2001 [Initial revision]
+ *
+ *
+ * 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>
+
+#define OUR_NAME "w83877f_wdt"
+
+#define ENABLE_W83877F_PORT 0x3F0
+#define ENABLE_W83877F 0x87
+#define DISABLE_W83877F 0xAA
+#define WDT_PING 0x443
+#define WDT_REGISTER 0x14
+#define WDT_ENABLE 0x9C
+#define WDT_DISABLE 0x8C
+
+/*
+ * The W83877F seems to be fixed at 1.6s timeout (at least on the
+ * EMACS PC-104 board I'm using). 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 int wdt_is_open;
+static int wdt_expect_close;
+
+/*
+ * 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 by reading from WDT_PING */
+ inb_p(WDT_PING);
+ /* 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_change(int writeval)
+{
+ /* buy some time */
+ inb_p(WDT_PING);
+
+ /* make W83877F available */
+ outb_p(ENABLE_W83877F,ENABLE_W83877F_PORT);
+ outb_p(ENABLE_W83877F,ENABLE_W83877F_PORT);
+
+ /* enable watchdog */
+ outb_p(WDT_REGISTER,ENABLE_W83877F_PORT);
+ outb_p(writeval,ENABLE_W83877F_PORT+1);
+
+ /* lock the W8387FF away */
+ outb_p(DISABLE_W83877F,ENABLE_W83877F_PORT);
+}
+
+static void wdt_startup(void)
+{
+ next_heartbeat = jiffies + WDT_HEARTBEAT;
+
+ /* Start the timer */
+ timer.expires = jiffies + WDT_INTERVAL;
+ add_timer(&timer);
+
+ wdt_change(WDT_ENABLE);
+
+ printk(OUR_NAME ": Watchdog timer is now enabled.\n");
+}
+
+static void wdt_turnoff(void)
+{
+ /* Stop the timer */
+ del_timer(&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)
+{
+ switch(MINOR(inode->i_rdev))
+ {
+ case WATCHDOG_MINOR:
+ /* Just in case we're already talking to someone... */
+ if(wdt_is_open)
+ return -EBUSY;
+ /* Good, fire up the show */
+ wdt_is_open = 1;
+ wdt_startup();
+ return 0;
+
+ default:
+ return -ENODEV;
+ }
+}
+
+static int fop_close(struct inode * inode, struct file * file)
+{
+ lock_kernel();
+ 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");
+ }
+ }
+ wdt_is_open = 0;
+ unlock_kernel();
+ 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,
+ "W83877F"
+ };
+
+ 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,
+ 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();
+ 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 w83877f_wdt_unload(void)
+{
+ wdt_turnoff();
+
+ /* Deregister */
+ misc_deregister(&wdt_miscdev);
+
+ unregister_reboot_notifier(&wdt_notifier);
+ release_region(WDT_PING,1);
+ release_region(ENABLE_W83877F_PORT,2);
+}
+
+static int __init w83877f_wdt_init(void)
+{
+ int rc = -EBUSY;
+
+ if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT"))
+ goto err_out;
+ if (!request_region(WDT_PING, 1, "W8387FF WDT"))
+ goto err_out_region1;
+
+ 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;
+
+ printk(KERN_INFO OUR_NAME ": WDT driver for W83877F initialised.\n");
+
+ return 0;
+
+err_out_miscdev:
+ misc_deregister(&wdt_miscdev);
+err_out_region2:
+ release_region(WDT_PING,1);
+err_out_region1:
+ release_region(ENABLE_W83877F_PORT,2);
+err_out:
+ return rc;
+}
+
+module_init(w83877f_wdt_init);
+module_exit(w83877f_wdt_unload);
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