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>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/arm/include/asm/arch-mx6/imx-regs.h b/arch/arm/include/asm/arch-mx6/imx-regs.h
index 3eb0081ca8..eaa7439486 100644
--- a/arch/arm/include/asm/arch-mx6/imx-regs.h
+++ b/arch/arm/include/asm/arch-mx6/imx-regs.h
@@ -601,5 +601,13 @@ struct iomuxc_base_regs {
 	u32     daisy[104];     /* 0x7b0..94c */
 };
 
+struct wdog_regs {
+	u16	wcr;	/* Control */
+	u16	wsr;	/* Service */
+	u16	wrsr;	/* Reset Status */
+	u16	wicr;	/* Interrupt Control */
+	u16	wmcr;	/* Miscellaneous Control */
+};
+
 #endif /* __ASSEMBLER__*/
 #endif /* __ASM_ARCH_MX6_IMX_REGS_H__ */