tegra2: Add arch_cpu_init() to fire up Cortex-A9

We want to move away from a special Tegra2 start-up, and just use
arch_cpu_init() instead. However, if we run board_init_f() from boot
we need to build it for ARMv4T, since the Tegra's AVP start-up CPU
does not support ARMv7.

The effect of this is to do the AVP init earlier, and in
arch_cpu_init(), rather that board_early_init_f().

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/cpu/armv7/tegra2/board.c

@@ -23,6 +23,7 @@
 
 #include <common.h>
 #include <asm/io.h>
+#include "ap20.h"
 #include <asm/arch/sys_proto.h>
 #include <asm/arch/tegra2.h>
 #include <asm/arch/pmc.h>
@@ -86,3 +87,17 @@ int checkboard(void)
 	return 0;
 }
 #endif	/* CONFIG_DISPLAY_BOARDINFO */
+
+#ifdef CONFIG_ARCH_CPU_INIT
+/*
+ * Note this function is executed by the ARM7TDMI AVP. It does not return
+ * in this case. It is also called once the A9 starts up, but does nothing in
+ * that case.
+ */
+int arch_cpu_init(void)
+{
+	/* Fire up the Cortex A9 */
+	tegra2_start();
+	return 0;
+}
+#endif

arch/arm/cpu/armv7/tegra2/config.mk

@@ -26,3 +26,9 @@
 
 # Use ARMv4 for Tegra2 - initial code runs on the AVP, which is an ARM7TDI.
 PLATFORM_CPPFLAGS += -march=armv4
+
+# Tegra has an ARMv4T CPU which runs board_init_f(), so we must build this
+# file with compatible flags
+ifdef CONFIG_TEGRA2
+CFLAGS_arch/arm/lib/board.o += -march=armv4t
+endif

board/nvidia/common/board.c

@@ -125,9 +125,6 @@ int board_early_init_f(void)
 
 	/* Initialize periph GPIOs */
 	gpio_config_uart();
-
-	/* Init UART, scratch regs, and start CPU */
-	tegra2_start();
 	return 0;
 }
 #endif	/* EARLY_INIT */

board/nvidia/common/board.h

@@ -24,7 +24,6 @@
 #ifndef _BOARD_H_
 #define _BOARD_H_
 
-void tegra2_start(void);
 void gpio_config_uart(void);
 int tegra2_mmc_init(int dev_index, int bus_width, int pwr_gpio, int cd_gpio);
 

include/configs/tegra2-common.h

@@ -35,6 +35,7 @@
 
 #define CONFIG_SYS_CACHELINE_SIZE	32
 
+#define CONFIG_ARCH_CPU_INIT		/* Fire up the A9 core */
 #define CONFIG_ENABLE_CORTEXA9		/* enable CPU (A9 complex) */
 
 #include <asm/arch/tegra2.h>		/* get chip and board defs */