ARM: tegra: Pass uncompress.h UART selection to DEBUG_LL

uncompress.h now saves the selected UART's physical address in Tegra's
IRAM, along with a cookie to indicate validity.

The first time it's run, macro addruart in debug-macro.S looks for this
cookie, and if it's present, uses the UART address stored there. If not,
the static value TEGRA_DEBUG_UART_BASE is used, as was previous behaviour.
The static behaviour will thus be used when not booting using a zImage.

This work was inspired by work by Doug Anderson <dianders@chromium.org>;
see http://lkml.org/lkml/2011/9/26/284. However, this patch relies on
the data passing describe above, rather than duplicating the UART
selection logic in debug-macro.S; the latest selection logic is more
complex due to the need to check reset/clock bits too.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Doug Anderson <dianders@chromium.org>
Acked-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 14 insertions, 1 deletions

diff --git a/arch/arm/mach-tegra/include/mach/uncompress.h b/arch/arm/mach-tegra/include/mach/uncompress.h
index 6c087b6974b2..b066ba0ee3c3 100644
--- a/arch/arm/mach-tegra/include/mach/uncompress.h
+++ b/arch/arm/mach-tegra/include/mach/uncompress.h
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2010 Google, Inc.
  * Copyright (C) 2011 Google, Inc.
- * Copyright (C) 2011 NVIDIA CORPORATION. All Rights Reserved.
+ * Copyright (C) 2011-2012 NVIDIA CORPORATION. All Rights Reserved.
  *
  * Author:
  *	Colin Cross <ccross@google.com>
@@ -30,6 +30,7 @@
 #include <linux/serial_reg.h>
 
 #include <mach/iomap.h>
+#include <mach/irammap.h>
 
 #define DEBUG_UART_SHIFT 2
 
@@ -49,6 +50,17 @@ static inline void flush(void)
 {
 }
 
+static inline void save_uart_address(void)
+{
+	u32 *buf = (u32 *)(TEGRA_IRAM_BASE + TEGRA_IRAM_DEBUG_UART_OFFSET);
+
+	if (uart) {
+		buf[0] = TEGRA_IRAM_DEBUG_UART_COOKIE;
+		buf[1] = (u32)uart;
+	} else
+		buf[0] = 0;
+}
+
 /*
  * Setup before decompression.  This is where we do UART selection for
  * earlyprintk and init the uart_base register.
@@ -125,6 +137,7 @@ static inline void arch_decomp_setup(void)
 	}
 	if (i == ARRAY_SIZE(uarts))
 		uart = (volatile u8 *)TEGRA_DEBUG_UART_BASE;
+	save_uart_address();
 	if (uart == NULL)
 		return;