[PATCH] Watchdog on MPC85xx SMP system

[Chen Gong]

On Book-E SMP systems each core has its own private watchdog.
If only one watchdog is enabled, when the core that doesn't
enable the watchdog is hung, system can't reset because no
watchdog is running on it. That's bad. It means we must
enable watchdogs on both cores.

We can use smp_call_function() to send appropriate messages to
all the other cores to enable and update the watchdog.

Signed-off-by: Chen Gong <g.chen at freescale.com>
---
Now Tested on MPC8572DS platform.

 drivers/watchdog/booke_wdt.c |   31 +++++++++++++++++++++++--------
 1 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/watchdog/booke_wdt.c b/drivers/watchdog/booke_wdt.c
index d362f5b..8a4e7f0 100644
--- a/drivers/watchdog/booke_wdt.c
+++ b/drivers/watchdog/booke_wdt.c
@@ -1,12 +1,12 @@
 /*
- * drivers/char/watchdog/booke_wdt.c
+ * drivers/watchdog/booke_wdt.c
  *
  * Watchdog timer for PowerPC Book-E systems
  *
  * Author: Matthew McClintock
  * Maintainer: Kumar Gala <galak at kernel.crashing.org>
  *
- * Copyright 2005 Freescale Semiconductor Inc.
+ * Copyright 2005, 2008 Freescale Semiconductor Inc.
  *
  * 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
@@ -16,6 +16,7 @@
 
 #include <linux/module.h>
 #include <linux/fs.h>
+#include <linux/smp.h>
 #include <linux/miscdevice.h>
 #include <linux/notifier.h>
 #include <linux/watchdog.h>
@@ -47,23 +48,31 @@ u32 booke_wdt_period = WDT_PERIOD_DEFAULT;
 #define WDTP(x)		(TCR_WP(x))
 #endif
 
+static DEFINE_SPINLOCK(booke_wdt_lock);
+
+static void __booke_wdt_ping(void *data)
+{
+	mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
+}
+
 /*
  * booke_wdt_ping:
  */
 static __inline__ void booke_wdt_ping(void)
 {
-	mtspr(SPRN_TSR, TSR_ENW|TSR_WIS);
+	smp_call_function(__booke_wdt_ping, NULL, 0, 0);
+	__booke_wdt_ping(NULL);
 }
 
 /*
- * booke_wdt_enable:
+ * __booke_wdt_enable:
  */
-static __inline__ void booke_wdt_enable(void)
+static inline void __booke_wdt_enable(void *data)
 {
 	u32 val;
 
 	/* clear status before enabling watchdog */
-	booke_wdt_ping();
+	__booke_wdt_ping(NULL);
 	val = mfspr(SPRN_TCR);
 	val |= (TCR_WIE|TCR_WRC(WRC_CHIP)|WDTP(booke_wdt_period));
 
@@ -137,12 +146,15 @@ static int booke_wdt_ioctl (struct inode *inode, struct file *file,
  */
 static int booke_wdt_open (struct inode *inode, struct file *file)
 {
+	spin_lock(&booke_wdt_lock);
 	if (booke_wdt_enabled == 0) {
 		booke_wdt_enabled = 1;
-		booke_wdt_enable();
+		__booke_wdt_enable(NULL);
+		smp_call_function(__booke_wdt_enable, NULL, 0, 0);
 		printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 				booke_wdt_period);
 	}
+	spin_unlock(&booke_wdt_lock);
 
 	return nonseekable_open(inode, file);
 }
@@ -183,11 +195,14 @@ static int __init booke_wdt_init(void)
 		return ret;
 	}
 
+	spin_lock(&booke_wdt_lock);
 	if (booke_wdt_enabled == 1) {
 		printk (KERN_INFO "PowerPC Book-E Watchdog Timer Enabled (wdt_period=%d)\n",
 				booke_wdt_period);
-		booke_wdt_enable();
+		__booke_wdt_enable(NULL);
+		smp_call_function(__booke_wdt_enable, NULL, 0, 0);
 	}
+	spin_unlock(&booke_wdt_lock);
 
 	return ret;
 }
-- 
1.5.4