[PATCH 2/3] board: starqltechn: get board usable - add bootcmd and docs

[sankouski-dzmitry]

From: Dzmitry Sankouski <dsankouski at gmail.com>

U-boot is intended to replace linux kernel in android boot image(ABL), and
it's FIT payload to replace initramfs file. The boot process is similar to
boot image with linux:
- android bootloader (ABL) unpacks android boot image
- ABL sets `linux,initrd-start property` in chosen node in unpacked FDT
- ABL sets x0 register to FDT address, and passes control to u-boot
- u-boot reads x0 register, and stores it in `prevbl_fdt_addr` env variable
- u-boot reads `linux,initrd-start` property,
and stores it in `prevbl_initrd_start_addr`

In this way, u-boot bootcmd relies on `prevbl_initrd_start_addr` env
variable, and boils down to `bootm $prevbl_initrd_start_addr`.
If more control on boot process is desired, pack a boot script in
FIT image, and put it to default configuration

What done:
- strip unneeded config options
- add FIT image support
- increase LMB_MAX_REGIONS, to store all linux dtb reserved memory regions
- add linux kernel image header

Uart driver causes hang, when u-boot is used in android boot image instead
of linux. Temporary disable console driver, until investigated and fixed.

Signed-off-by: sankouski-dzmitry <sankouski.dzmitry at gmail.com>
Cc: Ramon Fried <rfried.dev at gmail.com>
---
 configs/starqltechn_defconfig | 12 ++++++---
 doc/board/qualcomm/sdm845.rst | 47 ++++++++++++++++++++++++++++++++++-
 include/configs/sdm845.h      |  5 ++++
 3 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/configs/starqltechn_defconfig b/configs/starqltechn_defconfig
index f57bb859cc..48b16c1da5 100644
--- a/configs/starqltechn_defconfig
+++ b/configs/starqltechn_defconfig
@@ -2,13 +2,14 @@ CONFIG_ARM=y
 CONFIG_SKIP_LOWLEVEL_INIT=y
 CONFIG_POSITION_INDEPENDENT=y
 CONFIG_ARCH_SNAPDRAGON=y
-CONFIG_SYS_TEXT_BASE=0x80000000
-CONFIG_SYS_MALLOC_LEN=0x81f000
 CONFIG_DEFAULT_DEVICE_TREE="starqltechn"
+CONFIG_BOOTDELAY=0
+CONFIG_FIT=y
+CONFIG_FIT_VERBOSE=y
 CONFIG_TARGET_STARQLTECHN=y
 CONFIG_IDENT_STRING="\nSamsung S9 SM-G9600"
 CONFIG_SYS_LOAD_ADDR=0x80000000
-CONFIG_USE_PREBOOT=y
+CONFIG_LMB_MAX_REGIONS=64
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_GPIO=y
@@ -20,5 +21,8 @@ CONFIG_PM8916_GPIO=y
 CONFIG_PINCTRL=y
 CONFIG_DM_PMIC=y
 CONFIG_PMIC_PM8916=y
-CONFIG_MSM_GENI_SERIAL=y
+CONFIG_REQUIRE_SERIAL_CONSOLE=n
+CONFIG_MSM_GENI_SERIAL=n
 CONFIG_SPMI_MSM=y
+CONFIG_LINUX_KERNEL_IMAGE_HEADER=y
+CONFIG_SAVE_PREV_BL_INITRAMFS_START_ADDR=y
diff --git a/doc/board/qualcomm/sdm845.rst b/doc/board/qualcomm/sdm845.rst
index cd46cbe9cf..b00a30a313 100644
--- a/doc/board/qualcomm/sdm845.rst
+++ b/doc/board/qualcomm/sdm845.rst
@@ -17,7 +17,9 @@ It is loaded as an Android boot image through ABL
 
 Installation
 ------------
-First, setup ``CROSS_COMPILE`` for aarch64. Then, build U-Boot for your board::
+Build
+^^^^^^^^^^^^^^^^^^^^^^^^
+Setup ``CROSS_COMPILE`` for aarch64 and build U-Boot for your board::
 
 	$ export CROSS_COMPILE=<aarch64 toolchain prefix>
 	$ make <your board name here, see Boards section>_defconfig
@@ -25,6 +27,49 @@ First, setup ``CROSS_COMPILE`` for aarch64. Then, build U-Boot for your board::
 
 This will build ``u-boot.bin`` in the configured output directory.
 
+Generate FIT image
+^^^^^^^^^^^^^^^^^^^^^^^^
+See doc/uImage.FIT for more details
+
+Pack android boot image
+^^^^^^^^^^^^^^^^^^^^^^^^
+We'll assemble android boot image with ``u-boot.bin`` instead of linux kernel,
+and FIT image instead of ``initramfs``. Android bootloader expect gzipped kernel
+with appended dtb, so let's mimic linux to satisfy stock bootloader:
+
+- create dump dtb::
+
+	workdir=/tmp/prepare_payload
+	mkdir -p "$workdir"
+	cd "$workdir"
+	mock_dtb="$workdir"/payload_mock.dtb
+
+	dtc -I dts -O dtb -o "$mock_dtb" << EOF
+	/dts-v1/;
+	/ {
+		memory {
+			/* We expect the bootloader to fill in the size */
+			reg = <0 0 0 0>;
+		};
+
+		chosen { };
+	};
+	EOF
+
+- gzip u-boot ``gzip u-boot.bin``
+- append dtb to gzipped u-boot: ``cat u-boot.bin.gz "$mock_dtb" > u-boot.bin.gz-dtb``
+
+Now we've got everything to build android boot image:::
+
+	mkbootimg --base 0x0 --kernel_offset 0x00008000 \
+	--ramdisk_offset 0x02000000 --tags_offset 0x01e00000 \
+	--pagesize 4096 --second_offset 0x00f00000 \
+	--ramdisk "$fit_image" \
+	--kernel u-boot.bin.gz-dtb \
+	-o boot.img
+
+Flash image with your phone's flashing method.
+
 Boards
 ------------
 starqlte
diff --git a/include/configs/sdm845.h b/include/configs/sdm845.h
index af9ba197d4..398986bfcb 100644
--- a/include/configs/sdm845.h
+++ b/include/configs/sdm845.h
@@ -16,6 +16,11 @@
 /* Generic Timer Definitions */
 #define COUNTER_FREQUENCY	19000000
 
+#define CONFIG_EXTRA_ENV_SETTINGS \
+	"bootm_size=0x4000000\0"	\
+	"bootcmd=bootm $prevbl_initrd_start_addr\0"	\
+	"bootm_low=0x80000000\0"
+
 /* Size of malloc() pool */
 #define CONFIG_SYS_BOOTM_LEN	SZ_64M
 
-- 
2.25.1