[PATCH v3] mx35: Fix boot ROM hang in internal boot mode

[hjk@linutronix.de (Hans J. Koch)]

If a watchdog reset occurs after booting in internal boot mode, the i.MX35
won't boot anymore. The boot ROM code seems to assume that some clocks are
turned on (they are after a power-on reset). This patch turns on the
necessary clocks.

Signed-off-by: Hans J. Koch <hjk@linutronix.de>
---
 arch/arm/mach-mx3/clock-imx35.c |   20 ++++++++++++++++----
 1 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-mx3/clock-imx35.c b/arch/arm/mach-mx3/clock-imx35.c
index d3af0fd..32adf8d 100644
--- a/arch/arm/mach-mx3/clock-imx35.c
+++ b/arch/arm/mach-mx3/clock-imx35.c
@@ -485,10 +485,10 @@ static struct clk_lookup lookups[] = {
 
 int __init mx35_clocks_init()
 {
-	unsigned int ll = 0;
+	unsigned int cgr2 = 3 << 26, cgr3 = 0;
 
 #if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_ICEDCC)
-	ll = (3 << 16);
+	cgr2 |= 3 << 16;
 #endif
 
 	clkdev_add_table(lookups, ARRAY_SIZE(lookups));
@@ -499,8 +499,20 @@ int __init mx35_clocks_init()
 	__raw_writel((3 << 18), CCM_BASE + CCM_CGR0);
 	__raw_writel((3 << 2) | (3 << 4) | (3 << 6) | (3 << 8) | (3 << 16),
 			CCM_BASE + CCM_CGR1);
-	__raw_writel((3 << 26) | ll, CCM_BASE + CCM_CGR2);
-	__raw_writel(0, CCM_BASE + CCM_CGR3);
+
+	/*
+	 * Check if we came up in internal boot mode. If yes, we need some
+	 * extra clocks turned on, otherwise the MX35 boot ROM code will
+	 * hang after a watchdog reset.
+	 */
+	if (!(__raw_readl(CCM_BASE + CCM_RCSR) & (3 << 10))) {
+		/* Additionally turn on UART1, SCC, and IIM clocks */
+		cgr2 |= 3 << 16 | 3 << 4;
+		cgr3 |= 3 << 2;
+	}
+
+	__raw_writel(cgr2, CCM_BASE + CCM_CGR2);
+	__raw_writel(cgr3, CCM_BASE + CCM_CGR3);
 
 	mxc_timer_init(&gpt_clk,
 			MX35_IO_ADDRESS(MX35_GPT1_BASE_ADDR), MX35_INT_GPT);
-- 
1.7.1