[PATCH linux dev-4.7 v2] ARM: aspeed: witherspoon: Take UART1 out of reset

[Joel Stanley]

This is required so the UART can be used before booting the host.

Signed-off-by: Joel Stanley <joel at jms.id.au>

---
This is a minimal workaround for manufacturing. dev-4.10 will receive a
proper fix.

v2:
 - Make it compile

Signed-off-by: Joel Stanley <joel at jms.id.au>

 arch/arm/mach-aspeed/aspeed.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm/mach-aspeed/aspeed.c b/arch/arm/mach-aspeed/aspeed.c
index 0717181cc890..0d1dded5d91b 100644
--- a/arch/arm/mach-aspeed/aspeed.c
+++ b/arch/arm/mach-aspeed/aspeed.c
@@ -197,6 +197,8 @@ static void __init do_zaius_setup(void)
 
 static void __init do_witherspoon_setup(void)
 {
+	int reg;
+
 	do_common_setup();
 
 	/* Setup PNOR address mapping for 64M flash
@@ -216,6 +218,14 @@ static void __init do_witherspoon_setup(void)
 
 	/* Set SPI1 CE0 decoding window to 0x30000000 */
 	writel(0x68600000, AST_IO(AST_BASE_SPI | 0x30));
+
+        /* Disable default behavior of UART1 being held in reset by LPCRST#.
+         * By releasing UART1 from being controlled by LPC reset, it becomes
+         * immediately available regardless of the host being up.
+         */
+        reg = readl(AST_IO(AST_BASE_LPC | 0x98));
+        /* Clear "Enable UART1 reset source from LPC" */
+        writel(reg & ~BIT(4), AST_IO(AST_BASE_LPC | 0x98));
 }
 
 static void __init do_romulus_setup(void)
-- 
2.11.0