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>
---
 arch/arm/plat-s3c24xx/cpu.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'arch/arm/plat-s3c24xx/cpu.c')

diff --git a/arch/arm/plat-s3c24xx/cpu.c b/arch/arm/plat-s3c24xx/cpu.c
index f513ab083b8..f5699cadb0c 100644
--- a/arch/arm/plat-s3c24xx/cpu.c
+++ b/arch/arm/plat-s3c24xx/cpu.c
@@ -28,15 +28,19 @@
 #include <linux/ioport.h>
 #include <linux/serial_core.h>
 #include <linux/platform_device.h>
+#include <linux/delay.h>
 
 #include <asm/hardware.h>
 #include <asm/irq.h>
 #include <asm/io.h>
 #include <asm/delay.h>
+#include <asm/cacheflush.h>
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
 
+#include <asm/arch/system-reset.h>
+
 #include <asm/arch/regs-gpio.h>
 #include <asm/plat-s3c/regs-serial.h>
 
@@ -203,6 +207,27 @@ static unsigned long s3c24xx_read_idcode_v4(void)
 #endif
 }
 
+/* Hook for arm_pm_restart to ensure we execute the reset code
+ * with the caches enabled. It seems at least the S3C2440 has a problem
+ * resetting if there is bus activity interrupted by the reset.
+ */
+static void s3c24xx_pm_restart(char mode)
+{
+	if (mode != 's') {
+		unsigned long flags;
+
+		local_irq_save(flags);
+		__cpuc_flush_kern_all();
+		__cpuc_flush_user_all();
+
+		arch_reset(mode);
+		local_irq_restore(flags);
+	}
+
+	/* fallback, or unhandled */
+	arm_machine_restart(mode);
+}
+
 void __init s3c24xx_init_io(struct map_desc *mach_desc, int size)
 {
 	unsigned long idcode = 0x0;
@@ -230,6 +255,8 @@ void __init s3c24xx_init_io(struct map_desc *mach_desc, int size)
 		panic("Unsupported S3C24XX CPU");
 	}
 
+	arm_pm_restart = s3c24xx_pm_restart;
+
 	(cpu->map_io)(mach_desc, size);
 }
 
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