[U-Boot] [PATCH] imx: save reset cause in 'reset_cause' environment variable

[Eric Nelson]

The cause of a reset is generally useful, and shouldn't be
blindly cleared in the process of displaying it as a part
of the boot announcement.

Stash the string representation in the environment variable
"reset_cause".

The value is stored in hex, and the values may vary with
new silicon. As of this reading the following bitfields
are common to at least i.MX5 and i.MX6 processors:

	bit	meaning
	---	-------
	 0	reset pin or power-on
	 2	reset from csu_reset_b input
	 3	reset from ipp_user_reset_b
	 4	watchdog reset
	 5	JTAG High-Z requested reset
	 6	JTAG software reset
	 16	Warm boot: result of a software initiated boot

Signed-off-by: Eric Nelson <eric.nelson at boundarydevices.com>
---
 arch/arm/imx-common/cpu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/imx-common/cpu.c b/arch/arm/imx-common/cpu.c
index 28ccd29..31d6e61 100644
--- a/arch/arm/imx-common/cpu.c
+++ b/arch/arm/imx-common/cpu.c
@@ -32,6 +32,8 @@ char *get_reset_cause(void)
 	cause = readl(&src_regs->srsr);
 	writel(cause, &src_regs->srsr);
 
+	setenv_hex("reset_cause", cause);
+
 	switch (cause) {
 	case 0x00001:
 	case 0x00011:
-- 
1.9.1