[ARM] 4907/1: [AT91] SAM9/CAP9 reset reason

The Reset controller on the SAM9/CAP9 processors will store the reason
for the last system reset.
On startup, display this information (wakeup signal, RTT alarm,
watchdog reset, user reset, etc)

Based on patch from David Brownell.

Signed-off-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 74 insertions, 0 deletions

diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index 77d9669810ed..39733b6992aa 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -83,6 +83,79 @@ static inline void sdram_selfrefresh_enable(void)
 #endif
 
 
+/*
+ * Show the reason for the previous system reset.
+ */
+#if defined(AT91_SHDWC)
+
+#include <asm/arch/at91_rstc.h>
+#include <asm/arch/at91_shdwc.h>
+
+static void __init show_reset_status(void)
+{
+	static char reset[] __initdata = "reset";
+
+	static char general[] __initdata = "general";
+	static char wakeup[] __initdata = "wakeup";
+	static char watchdog[] __initdata = "watchdog";
+	static char software[] __initdata = "software";
+	static char user[] __initdata = "user";
+	static char unknown[] __initdata = "unknown";
+
+	static char signal[] __initdata = "signal";
+	static char rtc[] __initdata = "rtc";
+	static char rtt[] __initdata = "rtt";
+	static char restore[] __initdata = "power-restored";
+
+	char *reason, *r2 = reset;
+	u32 reset_type, wake_type;
+
+	reset_type = at91_sys_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
+	wake_type = at91_sys_read(AT91_SHDW_SR);
+
+	switch (reset_type) {
+	case AT91_RSTC_RSTTYP_GENERAL:
+		reason = general;
+		break;
+	case AT91_RSTC_RSTTYP_WAKEUP:
+		/* board-specific code enabled the wakeup sources */
+		reason = wakeup;
+
+		/* "wakeup signal" */
+		if (wake_type & AT91_SHDW_WAKEUP0)
+			r2 = signal;
+		else {
+			r2 = reason;
+			if (wake_type & AT91_SHDW_RTTWK)	/* rtt wakeup */
+				reason = rtt;
+			else if (wake_type & AT91_SHDW_RTCWK)	/* rtc wakeup */
+				reason = rtc;
+			else if (wake_type == 0)	/* power-restored wakeup */
+				reason = restore;
+			else				/* unknown wakeup */
+				reason = unknown;
+		}
+		break;
+	case AT91_RSTC_RSTTYP_WATCHDOG:
+		reason = watchdog;
+		break;
+	case AT91_RSTC_RSTTYP_SOFTWARE:
+		reason = software;
+		break;
+	case AT91_RSTC_RSTTYP_USER:
+		reason = user;
+		break;
+	default:
+		reason = unknown;
+		break;
+	}
+	pr_info("AT91: Starting after %s %s\n", reason, r2);
+}
+#else
+static void __init show_reset_status(void) {}
+#endif
+
+
 static int at91_pm_valid_state(suspend_state_t state)
 {
 	switch (state) {
@@ -294,6 +367,7 @@ static int __init at91_pm_init(void)
 
 	suspend_set_ops(&at91_pm_ops);
 
+	show_reset_status();
 	return 0;
 }
 arch_initcall(at91_pm_init);