[PATCH] i8xx_tco.c: arm watchdog only when started

i8xx_tco.c v0.08: only "arm" the watchdog when the watchdog has been
started.  (Kernel Bug 4251: system reset when battery is read and i8xx_tco
driver loaded)

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 28 insertions, 13 deletions

diff --git a/drivers/char/watchdog/i8xx_tco.c b/drivers/char/watchdog/i8xx_tco.c
index f975dab1ddf9..a13395e2c372 100644
--- a/drivers/char/watchdog/i8xx_tco.c
+++ b/drivers/char/watchdog/i8xx_tco.c
@@ -1,5 +1,5 @@
 /*
- *      i8xx_tco 0.07:  TCO timer driver for i8xx chipsets
+ *      i8xx_tco:       TCO timer driver for i8xx chipsets
  *
  *      (c) Copyright 2000 kernel concepts <nils@kernelconcepts.de>, All Rights Reserved.
  *                              http://www.kernelconcepts.de
@@ -63,6 +63,9 @@
  *  20050128 Wim Van Sebroeck <wim@iguana.be>
  *      0.07 Added support for the ICH4-M, ICH6, ICH6R, ICH6-M, ICH6W and ICH6RW
  *           chipsets. Also added support for the "undocumented" ICH7 chipset.
+ *  20050807 Wim Van Sebroeck <wim@iguana.be>
+ *      0.08 Make sure that the watchdog is only "armed" when started.
+ *           (Kernel Bug 4251)
  */
 
 /*
@@ -87,7 +90,7 @@
 #include "i8xx_tco.h"
 
 /* Module and version information */
-#define TCO_VERSION "0.07"
+#define TCO_VERSION "0.08"
 #define TCO_MODULE_NAME "i8xx TCO timer"
 #define TCO_DRIVER_NAME   TCO_MODULE_NAME ", v" TCO_VERSION
 #define PFX TCO_MODULE_NAME ": "
@@ -125,10 +128,18 @@ static int tco_timer_start (void)
         unsigned char val;
 
         spin_lock(&tco_lock);
+
+        /* disable chipset's NO_REBOOT bit */
+        pci_read_config_byte (i8xx_tco_pci, 0xd4, &val);
+        val &= 0xfd;
+        pci_write_config_byte (i8xx_tco_pci, 0xd4, val);
+
+        /* Bit 11: TCO Timer Halt -> 0 = The TCO timer is enabled to count */
         val = inb (TCO1_CNT + 1);
         val &= 0xf7;
         outb (val, TCO1_CNT + 1);
         val = inb (TCO1_CNT + 1);
+
         spin_unlock(&tco_lock);
 
         if (val & 0x08)
@@ -138,13 +149,20 @@ static int tco_timer_start (void)
 
 static int tco_timer_stop (void)
 {
-        unsigned char val;
+        unsigned char val, val1;
 
         spin_lock(&tco_lock);
+        /* Bit 11: TCO Timer Halt -> 1 = The TCO timer is disabled */
         val = inb (TCO1_CNT + 1);
         val |= 0x08;
         outb (val, TCO1_CNT + 1);
         val = inb (TCO1_CNT + 1);
+
+        /* Set the NO_REBOOT bit to prevent later reboots, just for sure */
+        pci_read_config_byte (i8xx_tco_pci, 0xd4, &val1);
+        val1 |= 0x02;
+        pci_write_config_byte (i8xx_tco_pci, 0xd4, val1);
+
         spin_unlock(&tco_lock);
 
         if ((val & 0x08) == 0)
@@ -155,6 +173,7 @@ static int tco_timer_stop (void)
 static int tco_timer_keepalive (void)
 {
         spin_lock(&tco_lock);
+        /* Reload the timer by writing to the TCO Timer Reload register */
         outb (0x01, TCO1_RLD);
         spin_unlock(&tco_lock);
         return 0;
@@ -417,9 +436,8 @@ static unsigned char __init i8xx_tco_getdevice (void)
                         printk (KERN_ERR PFX "failed to get TCOBASE address\n");
                         return 0;
                 }
-                /*
-                 * Check chipset's NO_REBOOT bit
-                 */
+
+                /* Check chipset's NO_REBOOT bit */
                 pci_read_config_byte (i8xx_tco_pci, 0xd4, &val1);
                 if (val1 & 0x02) {
                         val1 &= 0xfd;
@@ -430,6 +448,10 @@ static unsigned char __init i8xx_tco_getdevice (void)
                                 return 0;       /* Cannot reset NO_REBOOT bit */
                         }
                 }
+                /* Disable reboots untill the watchdog starts */
+                val1 |= 0x02;
+                pci_write_config_byte (i8xx_tco_pci, 0xd4, val1);
+
                 /* Set the TCO_EN bit in SMI_EN register */
                 if (!request_region (SMI_EN + 1, 1, "i8xx TCO")) {
                         printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
@@ -505,17 +527,10 @@ out:
 
 static void __exit watchdog_cleanup (void)
 {
-        u8 val;
-
         /* Stop the timer before we leave */
         if (!nowayout)
                 tco_timer_stop ();
 
-        /* Set the NO_REBOOT bit to prevent later reboots, just for sure */
-        pci_read_config_byte (i8xx_tco_pci, 0xd4, &val);
-        val |= 0x02;
-        pci_write_config_byte (i8xx_tco_pci, 0xd4, val);
-
         /* Deregister */
         misc_deregister (&i8xx_tco_miscdev);
         unregister_reboot_notifier(&i8xx_tco_notifier);