[ARM PATCH] 2502/1: S3C2410 - watchdog during kernel uncompression

Patch from Ben Dooks

Enable the watchdog at the start of the kernel uncompression
stage, so that if any errors occur before the kernel reaches
the stage where it can start running processes then the system
will be reset.

Signed-off-by: Ben Dooks
Signed-off-by: Russell King

arch/arm/mach-s3c2410/Kconfig

@@ -59,6 +59,26 @@ config CPU_S3C2440
 	help
 	  Support for S3C2440 Samsung Mobile CPU based systems.
 
+comment "S3C2410 Boot"
+
+config S3C2410_BOOT_WATCHDOG
+	bool "S3C2410 Initialisation watchdog"
+	depends on ARCH_S3C2410 && S3C2410_WATCHDOG
+	help
+	  Say y to enable the watchdog during the kernel decompression
+	  stage. If the kernel fails to uncompress, then the watchdog
+	  will trigger a reset and the system should restart.
+
+	  Although this uses the same hardware unit as the kernel watchdog
+	  driver, it is not a replacement for it. If you use this option,
+	  you will have to use the watchdg driver to either stop the timeout
+	  or restart it. If you do not, then your kernel will reboot after
+	  startup.
+
+	  The driver uses a fixed timeout value, so the exact time till the
+	  system resets depends on the value of PCLK. The timeout on an
+	  200MHz s3c2410 should be about 30 seconds.
+
 comment "S3C2410 Setup"
 
 config S3C2410_DMA

include/asm-arm/arch-s3c2410/uncompress.h

@@ -15,6 +15,7 @@
  *  12-Mar-2004 BJD  Updated header protection
  *  12-Oct-2004 BJD  Take account of debug uart configuration
  *  15-Nov-2004 BJD  Fixed uart configuration
+ *  22-Feb-2005 BJD  Added watchdog to uncompress
 */
 
 #ifndef __ASM_ARCH_UNCOMPRESS_H
@@ -25,12 +26,16 @@
 /* defines for UART registers */
 #include "asm/arch/regs-serial.h"
 #include "asm/arch/regs-gpio.h"
+#include "asm/arch/regs-watchdog.h"
 
 #include <asm/arch/map.h>
 
 /* working in physical space... */
 #undef S3C2410_GPIOREG
+#undef S3C2410_WDOGREG
+
 #define S3C2410_GPIOREG(x) ((S3C2410_PA_GPIO + (x)))
+#define S3C2410_WDOGREG(x) ((S3C2410_PA_WATCHDOG + (x)))
 
 /* how many bytes we allow into the FIFO at a time in FIFO mode */
 #define FIFO_MAX	 (14)
@@ -56,21 +61,6 @@ uart_rd(unsigned int reg)
 }
 
 
-/* currently we do not need the watchdog... */
-#define arch_decomp_wdog()
-
-
-static void error(char *err);
-
-static void
-arch_decomp_setup(void)
-{
-	/* we may need to setup the uart(s) here if we are not running
-	 * on an BAST... the BAST will have left the uarts configured
-	 * after calling linux.
-	 */
-}
-
 /* we can deal with the case the UARTs are being run
  * in FIFO mode, so that we don't hold up our execution
  * waiting for tx to happen...
@@ -122,4 +112,47 @@ putstr(const char *ptr)
 	}
 }
 
+/* CONFIG_S3C2410_BOOT_WATCHDOG
+ *
+ * Simple boot-time watchdog setup, to reboot the system if there is
+ * any problem with the boot process
+*/
+
+#ifdef CONFIG_S3C2410_BOOT_WATCHDOG
+
+#define WDOG_COUNT (0xff00)
+
+#define __raw_writel(d,ad) do { *((volatile unsigned int *)(ad)) = (d); } while(0)
+
+static inline void arch_decomp_wdog(void)
+{
+	__raw_writel(WDOG_COUNT, S3C2410_WTCNT);
+}
+
+static void arch_decomp_wdog_start(void)
+{
+	__raw_writel(WDOG_COUNT, S3C2410_WTDAT);
+	__raw_writel(WDOG_COUNT, S3C2410_WTCNT);
+	__raw_writel(S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128 | S3C2410_WTCON_RSTEN | S3C2410_WTCON_PRESCALE(0x40), S3C2410_WTCON);
+}
+
+#else
+#define arch_decomp_wdog_start()
+#define arch_decomp_wdog()
+#endif
+
+static void error(char *err);
+
+static void
+arch_decomp_setup(void)
+{
+	/* we may need to setup the uart(s) here if we are not running
+	 * on an BAST... the BAST will have left the uarts configured
+	 * after calling linux.
+	 */
+
+	arch_decomp_wdog_start();
+}
+
+
 #endif /* __ASM_ARCH_UNCOMPRESS_H */