mx6: Disable Power Down Bit of watchdog
On a mx6qsabresd revision C board with rev1.2 mx6q, the system gets resetted
and it is not able to reach the Linux prompt.
Comparing the watchdog behaviour on a revB versus revC board:
- On a mx6qsabresd revB:
U-Boot > reset
resetting ...
U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46)
CPU: Freescale i.MX6Q rev1.1 at 792 MHz
Reset cause: WDOG
...
- On a mx6qsabresd revC:
U-Boot > reset
resetting ...
U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46)
CPU: Freescale i.MX6Q rev1.1 at 792 MHz
Reset cause: POR
So due to revC POR/watchdog circuitry whenever a watchdog occurs, it causes a POR.
Clearing the PDE - Power Down Enable bit of WMCR registers fixes the problem and
is also safe for all mx6 boards.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/cpu/armv7/mx6/soc.c b/arch/arm/cpu/armv7/mx6/soc.c
index a8aad5d..efe4136 100644
--- a/arch/arm/cpu/armv7/mx6/soc.c
+++ b/arch/arm/cpu/armv7/mx6/soc.c
@@ -30,6 +30,7 @@
#include <asm/arch/clock.h>
#include <asm/arch/sys_proto.h>
#include <asm/imx-common/boot_mode.h>
+#include <stdbool.h>
struct scu_regs {
u32 ctrl;
@@ -121,12 +122,23 @@
writel(reg, &anatop->reg_core);
}
+static void imx_set_wdog_powerdown(bool enable)
+{
+ struct wdog_regs *wdog1 = (struct wdog_regs *)WDOG1_BASE_ADDR;
+ struct wdog_regs *wdog2 = (struct wdog_regs *)WDOG2_BASE_ADDR;
+
+ /* Write to the PDE (Power Down Enable) bit */
+ writew(enable, &wdog1->wmcr);
+ writew(enable, &wdog2->wmcr);
+}
+
int arch_cpu_init(void)
{
init_aips();
set_vddsoc(1200); /* Set VDDSOC to 1.2V */
+ imx_set_wdog_powerdown(false); /* Disable PDE bit of WMCR register */
return 0;
}