ARM i.MX28: change default watchdog reset method

The default setting for the imx28 watchdog is to do a power-off reset. If the
SoC is only powered via battery, then the watchdog powers the chip down, though.
According to the datasheet it should still be possible to execute a proper POR
with battery power, but testing showed otherwise.
When the watchdog power-off reset is disabled, a software reset is executed
instead. This works with and without battery power.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/arm/mach-mxs/soc-imx28.c b/arch/arm/mach-mxs/soc-imx28.c
index a181b759cb..a5f3d685d7 100644
--- a/arch/arm/mach-mxs/soc-imx28.c
+++ b/arch/arm/mach-mxs/soc-imx28.c
@@ -21,6 +21,7 @@
 
 #define HW_CLKCTRL_RESET 0x1e0
 # define HW_CLKCTRL_RESET_CHIP (1 << 1)
+#define HW_CLKCTRL_WDOG_POR_DISABLE (1 << 5)
 
 /* Reset the full i.MX28 SoC via a chipset feature */
 void __noreturn reset_cpu(unsigned long addr)
@@ -35,3 +36,14 @@ void __noreturn reset_cpu(unsigned long addr)
 	/*NOTREACHED*/
 }
 EXPORT_SYMBOL(reset_cpu);
+
+static int imx28_init(void)
+{
+	/*
+	 * The default setting for the WDT is to do a POR. If the SoC is only
+	 * powered via battery, then a WDT reset powers the chip down instead
+	 * of resetting it. Use a software reset only.
+	 */
+	writel(HW_CLKCTRL_WDOG_POR_DISABLE, IMX_CCM_BASE + HW_CLKCTRL_RESET);
+}
+postcore_initcall(imx28_init);