U-boot is intended to replace linux kernel in android boot image, 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 `abl_fdt_addr` env variable
- u-boot reads `linux,initrd-start` property,
and stores it in `abl_initrd_start_addr`
In this way, u-boot bootcmd relies on `abl_initrd_start_addr` env variable,
and boils down to `bootm $abl_initrd_start_addr`. If more control on
boot process is desired, pack a boot script in FIT image, and put it to
default configuration
Signed-off-by: Dzmitry Sankouski <dsankou...@gmail.com>
Cc: Ramon Fried <rfried....@gmail.com>
Cc: Tom Rini <tr...@konsulko.com>
---
arch/arm/mach-snapdragon/init_sdm845.c | 60 ++++++++++++++++++++----
doc/board/qualcomm/sdm845.rst | 63 +++++++++++++++++++++++++-
include/configs/sdm845.h | 5 ++
3 files changed, 116 insertions(+), 12 deletions(-)
diff --git a/arch/arm/mach-snapdragon/init_sdm845.c
b/arch/arm/mach-snapdragon/init_sdm845.c
index 5f53c21947..6aeaeeb53a 100644
--- a/arch/arm/mach-snapdragon/init_sdm845.c
+++ b/arch/arm/mach-snapdragon/init_sdm845.c
@@ -7,6 +7,7 @@
#include <init.h>
#include <env.h>
+#include <fdtdec.h>
#include <common.h>
#include <asm/system.h>
#include <asm/gpio.h>
@@ -14,6 +15,14 @@
DECLARE_GLOBAL_DATA_PTR;
+static ulong fdt_addr __section(".data");
+
+void save_boot_params(ulong r0)
+{
+ fdt_addr = r0;
+ save_boot_params_ret();
+}
+
int dram_init(void)
{
return fdtdec_setup_mem_size_base();
@@ -29,8 +38,33 @@ __weak int board_init(void)
return 0;
}
-/* Check for vol- and power buttons */
-__weak int misc_init_r(void)
+void set_abl_env(void)
+{
+ const void *fdt_blob;
+ int node, ret;
+ ulong initrd_start_prop;
+
+ ret = env_set_addr("abl_fdt_addr", fdt_addr);
+ if (ret < 0) {
+ printf("Failed to set abl device tree address\n");
+ return;
+ }
+
+ fdt_blob = (void *)fdt_addr;
+ node = fdt_path_offset(fdt_blob, "/chosen");
+ if (!node) {
+ printf("Chosen node not found in device tree at addr: 0x%ll\n",
fdt_addr);
+ return;
+ }
+ initrd_start_prop = fdtdec_get_addr(fdt_blob, node,
"linux,initrd-start");
+ if (!initrd_start_prop) {
+ printf("linux,initrd-start property is not set\n");
+ return;
+ }
+ env_set_addr("abl_initrd_start_addr", initrd_start_prop);
+}
+
+void read_pressed_keys(void)
{
struct udevice *pon;
struct gpio_desc resin;
@@ -39,19 +73,19 @@ __weak int misc_init_r(void)
ret = uclass_get_device_by_name(UCLASS_GPIO, "pm8998_pon@800", &pon);
if (ret < 0) {
printf("Failed to find PMIC pon node. Check device tree\n");
- return 0;
+ return;
}
node = fdt_subnode_offset(gd->fdt_blob, dev_of_offset(pon),
- "key_vol_down");
+ "key_vol_down");
if (node < 0) {
printf("Failed to find key_vol_down node. Check device tree\n");
- return 0;
+ return;
}
if (gpio_request_by_name_nodev(offset_to_ofnode(node), "gpios", 0,
- &resin, 0)) {
+ &resin, 0)) {
printf("Failed to request key_vol_down button.\n");
- return 0;
+ return;
}
if (dm_gpio_get_value(&resin)) {
env_set("key_vol_down", "1");
@@ -64,12 +98,12 @@ __weak int misc_init_r(void)
"key_power");
if (node < 0) {
printf("Failed to find key_power node. Check device tree\n");
- return 0;
+ return;
}
if (gpio_request_by_name_nodev(offset_to_ofnode(node), "gpios", 0,
- &resin, 0)) {
+ &resin, 0)) {
printf("Failed to request key_power button.\n");
- return 0;
+ return;
}
if (dm_gpio_get_value(&resin)) {
env_set("key_power", "1");
@@ -77,6 +111,12 @@ __weak int misc_init_r(void)
} else {
env_set("key_power", "0");
}
+}
+
+__weak int misc_init_r(void)
+{
+ set_abl_env();
+ read_pressed_keys();
return 0;
}
diff --git a/doc/board/qualcomm/sdm845.rst b/doc/board/qualcomm/sdm845.rst
index cd46cbe9cf..e14fd05118 100644
--- a/doc/board/qualcomm/sdm845.rst
+++ b/doc/board/qualcomm/sdm845.rst
@@ -13,11 +13,27 @@ SDM845 - hi-end qualcomm chip, introduced in late 2017.
Mostly used in flagship phones and tablets of 2018.
U-Boot can be used as a replacement for Qualcomm's original ABL (UEFI)
bootloader.
-It is loaded as an Android boot image through ABL
+It's replaces linux kernel in android boot image, and
+it's FIT payload replaces initramfs file. The boot process is similar to
+boot image with linux:
+
+- 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 `abl_fdt_addr` env variable
+- u-boot reads `linux,initrd-start` property,
+and stores it in `abl_initrd_start_addr`
+
+In this way, u-boot bootcmd relies on `abl_initrd_start_addr` env variable,
+and boils down to `bootm $abl_initrd_start_addr`. If more control on
+boot process is desired, pack a boot script in FIT image, and put it to
+default configuration
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 +41,49 @@ 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..cdf0f7e030 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 $abl_initrd_start_addr\0" \
+ "bootm_low=0x80000000\0"
+
/* Size of malloc() pool */
#define CONFIG_SYS_BOOTM_LEN SZ_64M
--
2.20.1
