ARM: mxs: Get boot mode from OCRAM

Reading the boot mode pins after power-up does not necessarily represent the
boot mode used by the ROM loader. For example the state of a pin may have
changed because a recovery switch which was pressed to enter USB mode is
already released after plugging in USB.

The ROM loader stores the value a fixed address in OCRAM. Use this value
instead of reading the boot map pins.

The GLOBAL_BOOT_MODE_ADDR for i.MX28 is taken from an U-Boot patch for the
MX28EVK:
http://repository.timesys.com/buildsources/u/u-boot/u-boot-2009.08/u-boot-2009.08-mx28-201012211513.patch

Leave the boot mode detection for the i.MX23 untouched. Someone has to test
whether the i.MX ROM loader does also store the boot mode in OCRAM and if the
address match.

This patch superseeds my incorrect patch:
ARM: mxs: get boot mode from OTP
http://patchwork.ozlabs.org/patch/454930/Signed-off-by: NJörg Krause <joerg.krause@embedded.rocks>
Cc: Stefano Babic <sbabic@denx.de>

arch/arm/cpu/arm926ejs/mxs/spl_boot.c

@@ -49,13 +49,6 @@ static const iomux_cfg_t iomux_boot[] = {
 	MX23_PAD_LCD_D03__GPIO_1_3 | MUX_CONFIG_BOOTMODE_PAD,
 	MX23_PAD_LCD_D04__GPIO_1_4 | MUX_CONFIG_BOOTMODE_PAD,
 	MX23_PAD_LCD_D05__GPIO_1_5 | MUX_CONFIG_BOOTMODE_PAD,
-#elif defined(CONFIG_MX28)
-	MX28_PAD_LCD_D00__GPIO_1_0 | MUX_CONFIG_BOOTMODE_PAD,
-	MX28_PAD_LCD_D01__GPIO_1_1 | MUX_CONFIG_BOOTMODE_PAD,
-	MX28_PAD_LCD_D02__GPIO_1_2 | MUX_CONFIG_BOOTMODE_PAD,
-	MX28_PAD_LCD_D03__GPIO_1_3 | MUX_CONFIG_BOOTMODE_PAD,
-	MX28_PAD_LCD_D04__GPIO_1_4 | MUX_CONFIG_BOOTMODE_PAD,
-	MX28_PAD_LCD_D05__GPIO_1_5 | MUX_CONFIG_BOOTMODE_PAD,
 #endif
 };
 
@@ -65,10 +58,10 @@ static uint8_t mxs_get_bootmode_index(void)
 	int i;
 	uint8_t masked;
 
+#if defined(CONFIG_MX23)
 	/* Setup IOMUX of bootmode pads to GPIO */
 	mxs_iomux_setup_multiple_pads(iomux_boot, ARRAY_SIZE(iomux_boot));
 
-#if defined(CONFIG_MX23)
 	/* Setup bootmode pins as GPIO input */
 	gpio_direction_input(MX23_PAD_LCD_D00__GPIO_1_0);
 	gpio_direction_input(MX23_PAD_LCD_D01__GPIO_1_1);
@@ -83,21 +76,11 @@ static uint8_t mxs_get_bootmode_index(void)
 	bootmode |= (gpio_get_value(MX23_PAD_LCD_D03__GPIO_1_3) ? 1 : 0) << 3;
 	bootmode |= (gpio_get_value(MX23_PAD_LCD_D05__GPIO_1_5) ? 1 : 0) << 5;
 #elif defined(CONFIG_MX28)
-	/* Setup bootmode pins as GPIO input */
-	gpio_direction_input(MX28_PAD_LCD_D00__GPIO_1_0);
-	gpio_direction_input(MX28_PAD_LCD_D01__GPIO_1_1);
-	gpio_direction_input(MX28_PAD_LCD_D02__GPIO_1_2);
-	gpio_direction_input(MX28_PAD_LCD_D03__GPIO_1_3);
-	gpio_direction_input(MX28_PAD_LCD_D04__GPIO_1_4);
-	gpio_direction_input(MX28_PAD_LCD_D05__GPIO_1_5);
-
-	/* Read bootmode pads */
-	bootmode |= (gpio_get_value(MX28_PAD_LCD_D00__GPIO_1_0) ? 1 : 0) << 0;
-	bootmode |= (gpio_get_value(MX28_PAD_LCD_D01__GPIO_1_1) ? 1 : 0) << 1;
-	bootmode |= (gpio_get_value(MX28_PAD_LCD_D02__GPIO_1_2) ? 1 : 0) << 2;
-	bootmode |= (gpio_get_value(MX28_PAD_LCD_D03__GPIO_1_3) ? 1 : 0) << 3;
-	bootmode |= (gpio_get_value(MX28_PAD_LCD_D04__GPIO_1_4) ? 1 : 0) << 4;
-	bootmode |= (gpio_get_value(MX28_PAD_LCD_D05__GPIO_1_5) ? 1 : 0) << 5;
+	/* The global boot mode will be detected by ROM code and its value
+	 * is stored at the fixed address 0x00019BF0 in OCRAM.
+	 */
+#define GLOBAL_BOOT_MODE_ADDR 0x00019BF0
+	bootmode = __raw_readl(GLOBAL_BOOT_MODE_ADDR);
 #endif
 
 	for (i = 0; i < ARRAY_SIZE(mxs_boot_modes); i++) {