From 3c7d9c81e1302c244180e62999a08ca95b175cf5 Mon Sep 17 00:00:00 2001
From: Ben Dooks <ben-linux@fluff.org>
Date: Wed, 16 Apr 2008 00:15:20 +0100
Subject: [ARM] 4987/1: S3C24XX: Ensure watchdog reset initiated from cached
 code.

There seems to be some problem with at-least the S3C2440 and
bus traffic during an reset. It is unlikely, but still possible
that the system will hang in such a way that the watchdog cannot
get the system out of the state it is in.

Change to making the code that calls the watchdog reset run from
cached memory so that instruction fetches have quiesced before the
watchdog fires.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
 include/asm-arm/arch-s3c2410/system-reset.h | 64 +++++++++++++++++++++++++++++
 include/asm-arm/arch-s3c2410/system.h       | 46 +--------------------
 2 files changed, 65 insertions(+), 45 deletions(-)
 create mode 100644 include/asm-arm/arch-s3c2410/system-reset.h

(limited to 'include')

diff --git a/include/asm-arm/arch-s3c2410/system-reset.h b/include/asm-arm/arch-s3c2410/system-reset.h
new file mode 100644
index 00000000000..1615bce0c02
--- /dev/null
+++ b/include/asm-arm/arch-s3c2410/system-reset.h
@@ -0,0 +1,64 @@
+/* linux/include/asm-arm/arch-s3c2410/system-reset.h
+ *
+ * Copyright (c) 2008 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * S3C2410 - System define for arch_reset() function
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+
+#include <asm/plat-s3c/regs-watchdog.h>
+#include <asm/arch/regs-clock.h>
+
+#include <linux/clk.h>
+#include <linux/err.h>
+
+extern void (*s3c24xx_reset_hook)(void);
+
+static void
+arch_reset(char mode)
+{
+	struct clk *wdtclk;
+
+	if (mode == 's') {
+		cpu_reset(0);
+	}
+
+	if (s3c24xx_reset_hook)
+		s3c24xx_reset_hook();
+
+	printk("arch_reset: attempting watchdog reset\n");
+
+	__raw_writel(0, S3C2410_WTCON);	  /* disable watchdog, to be safe  */
+
+	wdtclk = clk_get(NULL, "watchdog");
+	if (!IS_ERR(wdtclk)) {
+		clk_enable(wdtclk);
+	} else
+		printk(KERN_WARNING "%s: warning: cannot get watchdog clock\n", __func__);
+
+	/* put initial values into count and data */
+	__raw_writel(0x80, S3C2410_WTCNT);
+	__raw_writel(0x80, S3C2410_WTDAT);
+
+	/* set the watchdog to go and reset... */
+	__raw_writel(S3C2410_WTCON_ENABLE|S3C2410_WTCON_DIV16|S3C2410_WTCON_RSTEN |
+		     S3C2410_WTCON_PRESCALE(0x20), S3C2410_WTCON);
+
+	/* wait for reset to assert... */
+	mdelay(500);
+
+	printk(KERN_ERR "Watchdog reset failed to assert reset\n");
+
+	/* delay to allow the serial port to show the message */
+	mdelay(50);
+
+	/* we'll take a jump through zero as a poor second */
+	cpu_reset(0);
+}
diff --git a/include/asm-arm/arch-s3c2410/system.h b/include/asm-arm/arch-s3c2410/system.h
index 14de4e596f8..ad258085e53 100644
--- a/include/asm-arm/arch-s3c2410/system.h
+++ b/include/asm-arm/arch-s3c2410/system.h
@@ -17,12 +17,8 @@
 #include <asm/arch/idle.h>
 #include <asm/arch/reset.h>
 
-#include <asm/plat-s3c/regs-watchdog.h>
 #include <asm/arch/regs-clock.h>
 
-#include <linux/clk.h>
-#include <linux/err.h>
-
 void (*s3c24xx_idle)(void);
 void (*s3c24xx_reset_hook)(void);
 
@@ -59,44 +55,4 @@ static void arch_idle(void)
 		s3c24xx_default_idle();
 }
 
-static void
-arch_reset(char mode)
-{
-	struct clk *wdtclk;
-
-	if (mode == 's') {
-		cpu_reset(0);
-	}
-
-	if (s3c24xx_reset_hook)
-		s3c24xx_reset_hook();
-
-	printk("arch_reset: attempting watchdog reset\n");
-
-	__raw_writel(0, S3C2410_WTCON);	  /* disable watchdog, to be safe  */
-
-	wdtclk = clk_get(NULL, "watchdog");
-	if (!IS_ERR(wdtclk)) {
-		clk_enable(wdtclk);
-	} else
-		printk(KERN_WARNING "%s: warning: cannot get watchdog clock\n", __func__);
-
-	/* put initial values into count and data */
-	__raw_writel(0x80, S3C2410_WTCNT);
-	__raw_writel(0x80, S3C2410_WTDAT);
-
-	/* set the watchdog to go and reset... */
-	__raw_writel(S3C2410_WTCON_ENABLE|S3C2410_WTCON_DIV16|S3C2410_WTCON_RSTEN |
-		     S3C2410_WTCON_PRESCALE(0x20), S3C2410_WTCON);
-
-	/* wait for reset to assert... */
-	mdelay(500);
-
-	printk(KERN_ERR "Watchdog reset failed to assert reset\n");
-
-	/* delay to allow the serial port to show the message */
-	mdelay(50);
-
-	/* we'll take a jump through zero as a poor second */
-	cpu_reset(0);
-}
+#include <asm/arch/system-reset.h>
-- 
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