[U-Boot] [PATCH v2] imx6: apalis: Make the boot process more generic

[Petr Štetiar]

I'm preparing support for Apalis imx6 boards in OpenWrt and I've ended
up with quite huge patchset against upstream U-Boot 2018.03, so I'm
trying to propose more generic way of boot process handling.

In OpenWrt we usually have kernel, dtbs and U-Boot boot script in boot
partition with ext4fs, so for some use cases it would be handy to be
able to replace some of the files in the boot partion, that's why I've
added write support to the ext4.

I've added `set_blkcnt` environment variable which is needed for every
`mmc write` command as we need to always specify size in block count.
This is copy&pasted from official Toradex's flashing scripts, so all the
credits for this work belongs to them.

Currently the rootfs location is passed via mmcblk number and the
problem with this approach is that the mmcblk number for the boot device
changes depending on the kernel version and imx6 SoC type.  In order to
avoid such issues, use the UUID method to specify the rootfs location.

I've added new boot sequence, where we first try to load and run boot
script defined in the new `script` variable, so the boot process could
be more generic and overridden by the distro. When the boot script isn't
loaded, it will use the previous boot sequence.

For the recovery purposes and better end user experience I've added boot
from SDP as the last boot command if every other boot option fails. I
plan to use SDP as official flashing/recovery procedure in OpenWrt for
Apalis imx6 boards.

I've copy&pasted almost everything from the `f086812a mx6sxsabresd: Use
PARTUUID to specify the rootfs location` commit, so credits for the rest
of this patch belongs to Fabio.

Cc: Stefan Agner <stefan.agner at toradex.com>
Cc: Max Krummenacher <max.krummenacher at toradex.com>
Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 configs/apalis_imx6_defconfig |  2 ++
 include/configs/apalis_imx6.h | 26 +++++++++++++++++++++-----
 2 files changed, 23 insertions(+), 5 deletions(-)

Changes since v1:

  * Made note about ext4 write support more clear
  * I've removed Kconfig variables and all variables which were coupled to the code
  * I've removed the note about backward compatibility from commit message,
    because I've realized, that this changes are not backward compatible,
    because this patch is switching to part UUID, so the distributions would
    need to provide filesystem with part UUID for rootfs.

diff --git a/configs/apalis_imx6_defconfig b/configs/apalis_imx6_defconfig
index 133fc1a..279d39f 100644
--- a/configs/apalis_imx6_defconfig
+++ b/configs/apalis_imx6_defconfig
@@ -39,6 +39,7 @@ CONFIG_CMD_DFU=y
 CONFIG_CMD_GPIO=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
+CONFIG_CMD_PART=y
 CONFIG_CMD_USB=y
 CONFIG_CMD_USB_SDP=y
 CONFIG_CMD_USB_MASS_STORAGE=y
@@ -48,6 +49,7 @@ CONFIG_CMD_PING=y
 CONFIG_CMD_BMP=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_EXT4=y
+CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_FAT=y
 CONFIG_CMD_FS_GENERIC=y
 CONFIG_ENV_IS_IN_MMC=y
diff --git a/include/configs/apalis_imx6.h b/include/configs/apalis_imx6.h
index 135b3c9..3601891 100644
--- a/include/configs/apalis_imx6.h
+++ b/include/configs/apalis_imx6.h
@@ -142,9 +142,9 @@
 	"imx6q-colibri-cam-eval-v3.dtb fat 0 1"
 
 #define EMMC_BOOTCMD \
-	"emmcargs=ip=off root=/dev/mmcblk0p2 rw,noatime rootfstype=ext3 " \
+	"emmcargs=ip=off root=PARTUUID=${uuid} rw,noatime rootfstype=ext3 " \
 		"rootwait\0" \
-	"emmcboot=run setup; " \
+	"emmcboot=run setup; run finduuid;" \
 		"setenv bootargs ${defargs} ${emmcargs} ${setupargs} " \
 		"${vidargs}; echo Booting from internal eMMC chip...; "	\
 		"run emmcdtbload; load mmc 0:1 ${kernel_addr_r} " \
@@ -201,10 +201,17 @@
 #define FDT_FILE "imx6q-apalis_v1_0-eval.dtb"
 #endif
 #define CONFIG_EXTRA_ENV_SETTINGS \
-	"bootcmd=run emmcboot ; echo ; echo emmcboot failed ; " \
+	"script=boot.scr\0" \
+	"finduuid=part uuid mmc 0:2 uuid\0" \
+	"loadbootscript=" \
+		"load mmc 0:1 ${loadaddr} ${script};\0" \
+	"bootscript=echo Running bootscript from mmc ...; " \
+		"source\0" \
+	"bootcmd_default=run emmcboot ; echo ; echo emmcboot failed ; " \
 		"run nfsboot ; echo ; echo nfsboot failed ; " \
 		"usb start ;" \
-		"setenv stdout serial,vga ; setenv stdin serial,usbkbd\0" \
+		"setenv stdout serial,vga ; setenv stdin serial,usbkbd;" \
+		"sdp 0\0" \
 	"boot_file=uImage\0" \
 	"console=ttymxc0\0" \
 	"defargs=enable_wait_mode=off vmalloc=400M\0" \
@@ -232,7 +239,16 @@
 	"vidargs=mxc_hdmi.only_cea=1 " \
 		"video=mxcfb0:dev=hdmi,1920x1080M at 60,if=RGB24 " \
 		"video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off " \
-		"fbmem=32M\0 "
+		"fbmem=32M\0 " \
+	"set_blkcnt=setexpr blkcnt ${filesize} + 0x1ff && setexpr blkcnt ${blkcnt} / 0x200\0"
+
+#define CONFIG_BOOTCOMMAND \
+	   "mmc dev 0;" \
+	   "if run loadbootscript; then " \
+		   "run bootscript; " \
+	   "else " \
+		   "run bootcmd_default; " \
+	   "fi; "
 
 /* Miscellaneous configurable options */
 #undef CONFIG_SYS_CBSIZE
-- 
1.9.1