mx6sabreauto: Add Falcon mode support

Add support for Falcon mode and explain in the README the steps to
boot the kernel directly without loading the full U-Boot.

Signed-off-by: Diego Dorta <diego.dorta@nxp.com>
Acked-by: Fabio Estevam <fabio.estevam@nxp.com>

board/freescale/mx6sabreauto/README

@@ -18,3 +18,65 @@ $ sudo dd if=SPL of=/dev/sdX bs=1K seek=1 && sync
 - Flash the u-boot.img binary into the SD card:
 
 $ sudo dd if=u-boot.img of=/dev/sdX bs=1K seek=69 && sync
+
+Booting via Falcon mode
+-----------------------
+
+Write in mx6sabreauto_defconfig the following define below:
+
+CONFIG_SPL_OS_BOOT=y
+
+In order to build it:
+
+$ make mx6sabreauto_defconfig
+
+$ make
+
+This will generate the SPL image called SPL and the u-boot.img.
+
+- Flash the SPL image into the SD card:
+
+$ sudo dd if=SPL of=/dev/sdb bs=1K seek=1 && sync
+
+- Flash the u-boot.img image into the SD card:
+
+$ sudo dd if=u-boot.img of=/dev/sdb bs=1K seek=69 && sync
+
+Create a FAT16 boot partition to store uImage and the dtb file, then copy the files there:
+
+$ sudo cp uImage /media/boot
+
+$ sudo cp imx6dl-sabreauto.dtb /media/boot
+
+Create a partition for root file system and extract it there:
+
+$ sudo tar xvf rootfs.tar.gz -C /media/root
+
+The SD card must have enough space for raw "args" and "kernel".
+To configure Falcon mode for the first time, on U-Boot do the following commands:
+
+- Load dtb file from boot partition:
+
+# load mmc 0:1 ${fdt_addr} imx6dl-sabreauto.dtb
+
+- Load kernel image from boot partition:
+
+# load mmc 0:1 ${loadaddr} uImage
+
+- Write kernel at 2MB offset:
+
+# mmc write ${loadaddr} 0x1000 0x4000
+
+- Setup kernel bootargs:
+
+# setenv bootargs "console=ttymxc3,115200 root=/dev/mmcblk0p1 rootfstype=ext4 rootwait quiet rw"
+
+- Prepare args:
+
+# spl export fdt ${loadaddr} - ${fdt_addr}
+
+- Write args 1MB data (0x800 sectors) to 1MB offset (0x800 sectors)
+
+# mmc write 18000000 0x800 0x800
+
+- Restart the board and then SPL binary will launch the kernel directly.

board/freescale/mx6sabreauto/mx6sabreauto.c

@@ -745,6 +745,13 @@ int board_ehci_power(int port, int on)
 #include <spl.h>
 #include <libfdt.h>
 
+#ifdef CONFIG_SPL_OS_BOOT
+int spl_start_uboot(void)
+{
+	return 0;
+}
+#endif
+
 static void ccgr_init(void)
 {
 	struct mxc_ccm_reg *ccm = (struct mxc_ccm_reg *)CCM_BASE_ADDR;

include/configs/mx6sabreauto.h

@@ -30,6 +30,20 @@
 
 #include "mx6sabre_common.h"
 
+/* Falcon Mode */
+#ifdef CONFIG_SPL_OS_BOOT
+#define CONFIG_SPL_FS_LOAD_ARGS_NAME	"args"
+#define CONFIG_SPL_FS_LOAD_KERNEL_NAME	"uImage"
+#define CONFIG_CMD_SPL
+#define CONFIG_SYS_SPL_ARGS_ADDR       0x18000000
+#define CONFIG_CMD_SPL_WRITE_SIZE      (128 * SZ_1K)
+
+/* Falcon Mode - MMC support: args@1MB kernel@2MB */
+#define CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR  0x800   /* 1MB */
+#define CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS (CONFIG_CMD_SPL_WRITE_SIZE / 512)
+#define CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR        0x1000  /* 2MB */
+#endif
+
 #ifdef CONFIG_MTD_NOR_FLASH
 #define CONFIG_SYS_FLASH_BASE           WEIM_ARB_BASE_ADDR
 #define CONFIG_SYS_FLASH_SECT_SIZE      (128 * 1024)