[PATHC V3] 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>
---
Tested on MPC8572DS platform.

 drivers/char/watchdog/booke_wdt.c |   34 +++++++++++++++++++++++++++-------
 1 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/drivers/char/watchdog/booke_wdt.c b/drivers/char/watchdog/booke_wdt.c
index d362f5b..b3a37d0 100644
--- a/drivers/char/watchdog/booke_wdt.c
+++ b/drivers/char/watchdog/booke_wdt.c
@@ -6,7 +6,12 @@
  * Author: Matthew McClintock
  * Maintainer: Kumar Gala <galak at kernel.crashing.org>
  *
- * Copyright 2005 Freescale Semiconductor Inc.
+ * Copyright 2005, 2008 Freescale Semiconductor Inc.
+ *
+ * Changelog:
+ * 	2008-04-28 Chen Gong <g.chen at freescale.com>
+ * 	Add SMP support for MPC85xx system. Tested on
+ * 	MPC8572DS platform
  *
  * 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 +21,7 @@
 
 #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 +53,31 @@ 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 +151,15 @@ 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 +200,14 @@ 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