[U-Boot] [PATCH v3 2/2] ls102xa: Fix reset hang

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam at freescale.com>

Since commit 623d96e89aca6("imx: wdog: correct wcr register settings")
issuing a 'reset' command causes the system to hang.

Unlike i.MX and Vybrid, the watchdog controller on LS102x is big-endian.

This means that the watchdog on LS1021 has been working by accident as
it does not use the big-endian accessors in drivers/watchdog/imx_watchdog.c.
Commit 623d96e89aca6("imx: wdog: correct wcr register settings") only
revelead the endianness problem on LS102x.

In order to fix the reset hang, introduce a reset_cpu() implementation that 
is specific for ls102x, which accesses the watchdog WCR register in big-endian
format. All that is required to reset LS102x is to clear the SRS bit.

This approach is a temporary workaround to avoid a regression for LS102x
in the 2015.10 release. The proper fix is to make the watchdog driver 
endian-aware, so that it can work for i.MX, Vybrid and LS102x.

Reported-by: Sinan Akman <sinan at writeme.com>
Tested-by: Sinan Akman <sinan at writeme.com>
Reviewed-by: Wolfgang Denk <wd at denx.de>
Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
Changes since v2:
- Explain that this a temporary workaround (Tom)
Changes since v1:
- Do not add duplicate wdog struct (Wolfgang)

 arch/arm/cpu/armv7/ls102xa/cpu.c | 15 +++++++++++++++
 drivers/watchdog/Makefile        |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/arm/cpu/armv7/ls102xa/cpu.c b/arch/arm/cpu/armv7/ls102xa/cpu.c
index 8dd95d9..e2eb5f3 100644
--- a/arch/arm/cpu/armv7/ls102xa/cpu.c
+++ b/arch/arm/cpu/armv7/ls102xa/cpu.c
@@ -13,6 +13,8 @@
 #include <tsec.h>
 #include <netdev.h>
 #include <fsl_esdhc.h>
+#include <config.h>
+#include <fsl_wdog.h>
 
 #include "fsl_epu.h"
 
@@ -354,3 +356,16 @@ void smp_kick_all_cpus(void)
 	asm volatile("sev");
 }
 #endif
+
+void reset_cpu(ulong addr)
+{
+	struct watchdog_regs *wdog = (struct watchdog_regs *)WDOG1_BASE_ADDR;
+
+	clrbits_be16(&wdog->wcr, WCR_SRS);
+
+	while (1) {
+		/*
+		 * Let the watchdog trigger
+		 */
+	}
+}
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 9e9cb55..a007ae8 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -7,7 +7,7 @@
 
 obj-$(CONFIG_AT91SAM9_WATCHDOG) += at91sam9_wdt.o
 obj-$(CONFIG_FTWDT010_WATCHDOG) += ftwdt010_wdt.o
-ifneq (,$(filter $(SOC), mx31 mx35 mx5 mx6 mx7 vf610 ls102xa))
+ifneq (,$(filter $(SOC), mx31 mx35 mx5 mx6 mx7 vf610))
 obj-y += imx_watchdog.o
 endif
 obj-$(CONFIG_S5P)               += s5p_wdt.o
-- 
1.9.1