在 Uboot 當中，一樣要去修改 DDR Size , 避免在Uboot 當中會出現認錯位置的情況。其餘的也是依照不同的開發板，或是你想要的不同功能來去做修改。例如你可能希望在這個階段，你要使用到RMII的功能，那就必須要在Uboot 的設備樹當中正確地去設定。
devtool modify u-boot-stm32mp
這部分是粗略的說明，主要其實我們只需要理解大致上的邏輯，不會真的需要去修改到他
其實當我們進到 uboot 當中 ， 也有非常多指令可以使用 。
例如 mmc list 可以用來查看 emmc ， print env 可以列出環境變數。
uboot bootcmd環境變數儲存了 uboot預設的指令， 啟動時會看到讀秒(大約一秒的時間，這時候按下 enter 就會進到 uboot) ，uboot倒數結束後就會執行bootcmd中的命令。下方是 bootcmd啟動linux的流程：
altbootcmd=run bootcmd
arch=arm
autoload=no
baudrate=115200
board=stm32mp1
board_name=stm32mp157d-robot
boot_a_script=load ${devtype} ${devnum}:${distro_bootpart} ${scriptaddr} ${prefix}${script}; source ${scriptaddr}
boot_device=mmc
boot_efi_binary=
if fdt addr ${fdt_addr_r}; then
bootefi bootmgr ${fdt_addr_r};
else
bootefi bootmgr ${fdtcontroladdr};
fi;
load ${devtype} ${devnum}:${distro_bootpart} ${kernel_addr_r} efi/boot/bootarm.efi;
if fdt addr ${fdt_addr_r}; then
bootefi ${kernel_addr_r} ${fdt_addr_r};
else
bootefi ${kernel_addr_r} ${fdtcontroladdr};
fi
boot_extlinux=sysboot ${devtype} ${devnum}:${distro_bootpart} any ${scriptaddr} ${prefix}${boot_syslinux_conf}
boot_instance=0
boot_m4fw=rproc init; rproc load 0 ${m4fw_addr} ${filesize}; rproc start 0
boot_net_usb_start=true
boot_prefixes=/ /boot/
boot_script_dhcp=boot.scr.uimg
boot_scripts=boot.scr.uimg boot.scr
boot_syslinux_conf=extlinux/extlinux.conf
boot_targets=mmc1 ubifs0 mmc0 mmc2 pxe
bootcmd=run bootcmd_stm32mp
bootcmd_mmc0=devnum=0; run mmc_boot
bootcmd_mmc1=devnum=1; run mmc_boot
bootcmd_mmc2=devnum=2; run mmc_boot
bootcmd_pxe=run boot_net_usb_start; dhcp; if pxe get; then pxe boot; fi
bootcmd_stm32mp=
echo "Boot over ${boot_device}${boot_instance}!";
if test ${boot_device} = serial || test ${boot_device} = usb;then
stm32prog ${boot_device} ${boot_instance};
else
run env_check;
if test ${boot_device} = mmc;then
env set boot_targets "mmc${boot_instance}";
fi;
if test ${boot_device} = nand || test ${boot_device} = spi-nand ;then
env set boot_targets ubifs0;
fi;
if test ${boot_device} = nor;then
env set boot_targets mmc0;
fi;
run distro_bootcmd;
fi;
bootcmd_ubifs0=devnum=0; run ubifs_boot
bootcount=4
bootdelay=1
bootfstype=ext4
cpu=armv7
distro_bootcmd=
for target in ${boot_targets};
do
run bootcmd_${target};
done
efi_dtb_prefixes=/ /dtb/ /dtb/current/
env_check=if env info -p -d -q; then env save; fi
fdt_addr_r=0xc4000000
fdtcontroladdr=f3ae4d20
fdtfile=stm32mp157d-robot.dtb
fdtoverlay_addr_r=0xc4100000
fileaddr=c4100000
filesize=b7f
kernel_addr_r=0xc2000000
load_efi_dtb=load ${devtype} ${devnum}:${distro_bootpart} ${fdt_addr_r} ${prefix}${efi_fdtfile}
loadaddr=0xc2000000
m4fw_addr=0xc2000000
m4fw_name=rproc-m4-fw.elf
mmc_boot=
if mmc dev ${devnum}; then
devtype=mmc;
run scan_dev_for_boot_part;
fi
pxefile_addr_r=0xc4200000
ramdisk_addr_r=0xc4400000
scan_dev_for_boot=
echo Scanning ${devtype} ${devnum}:${distro_bootpart}...;
for prefix in ${boot_prefixes};
do
run scan_dev_for_extlinux;
run scan_dev_for_scripts;
done;
run scan_dev_for_efi;
scan_dev_for_boot_part=
part list ${devtype} ${devnum} -bootable devplist;
env exists devplist || setenv devplist 1;
for distro_bootpart in ${devplist};
do
if fstype ${devtype} ${devnum}:${distro_bootpart} bootfstype; then
run scan_dev_for_boot;
fi;
done;
setenv devplist
scan_dev_for_efi=
setenv efi_fdtfile ${fdtfile};
if test -z "${fdtfile}" -a -n "${soc}"; then
setenv efi_fdtfile ${soc}-${board}${boardver}.dtb;
fi;
for prefix in ${efi_dtb_prefixes};
do
if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${efi_fdtfile}; then
run load_efi_dtb;
fi;
done;
if test -e ${devtype} ${devnum}:${distro_bootpart} efi/boot/bootarm.efi; then
echo Found EFI removable media binary efi/boot/bootarm.efi;
run boot_efi_binary; echo EFI LOAD FAILED: continuing...;
fi;
setenv efi_fdtfile
scan_dev_for_extlinux=
if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${boot_syslinux_conf}; then
echo Found ${prefix}${boot_syslinux_conf};
run boot_extlinux;
echo SCRIPT FAILED: continuing...;
fi
scan_dev_for_scripts=
for script in ${boot_scripts};
do
if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${script}; then
echo Found U-Boot script ${prefix}${script};
run boot_a_script;
echo SCRIPT FAILED: continuing...;
fi;
done
scan_m4fw=
if test -e ${devtype} ${devnum}:${distro_bootpart} ${m4fw_name};then
echo Found M4 FW $m4fw_name;
if load ${devtype} ${devnum}:${distro_bootpart} ${m4fw_addr} ${m4fw_name}; then
run boot_m4fw;
fi;
fi;
scriptaddr=0xc4100000
serial#=003A002B3030511039383538
serverip=192.168.1.1
soc=stm32mp
splashimage=0xc4300000
ubifs_boot=
env exists bootubipart || env set bootubipart UBI;
env exists bootubivol || env set bootubivol boot;
if ubi part ${bootubipart} && ubifsmount ubi${devnum}:${bootubivol}; then
devtype=ubi;
run scan_dev_for_boot;
fi
usb_boot=
usb start;
if usb dev ${devnum}; then
devtype=usb;
run scan_dev_for_boot_part;
fi
vendor=st
Environment size: 4413/8187 bytes
bootcmd=run bootcmd_stm32mp
bootcmd_stm32mp=
echo "Boot over ${boot_device}${boot_instance}!"; # ${boot_device}${boot_instance}: mmc0（sdcard 啟動，通常 mmc0 都會是 SD）
run env_check;
if test ${boot_device} = mmc;then
env set boot_targets "mmc${boot_instance}"; boot_targets mmc0
fi;
run distro_bootcmd;
distro_bootcmd=
for target in ${boot_targets};
do
run bootcmd_${target}; # run bootcmd_mmc0
done
bootcmd_mmc0=
devnum=0; # devnum=0
run mmc_boot
mmc_boot=
if mmc dev ${devnum}; then
devtype=mmc; # devtype=mmc
run scan_dev_for_boot_part;
fi
下方的 scan_dev_for_boot_part 函數就是去檢查mmc0的分區裡面是否有bootfs的分區lable，如果有找到對應的label，就對應上面的4分區，然後會去執行scan_dev_for_boot
scan_dev_for_boot_part=
part list ${devtype} ${devnum} -bootable devplist; #查看 SD的 boot 分區就是 mmc0
env exists devplist || setenv devplist 1;
for distro_bootpart in ${devplist};
do
if fstype ${devtype} ${devnum}:${distro_bootpart} bootfstype; then
run scan_dev_for_boot;
fi;
done;
setenv devplist
下方的函數是去找SD卡boot分割區裡面/ (根目錄) 和 /boot 兩個路徑下是否有extlinux.conf文件，如果找到這個文件就會去執行boot_extlinux。
scan_dev_for_extlinux=
if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${boot_syslinux_conf}; then
(/extlinux/extlinux.conf /boot/extlinux/extlinux.conf)
echo Found ${prefix}${boot_syslinux_conf};
run boot_extlinux;
echo SCRIPT FAILED: continuing...;
fi
boot_extlinux=
sysboot ${devtype} ${devnum}:${distro_bootpart} any ${scriptaddr} ${prefix}${boot_syslinux_conf}
---> sysboot mmc 0：4 any 0xc4100000 (/extlinux/extlinux.conf /boot/extlinux/extlinux.conf)
scan_dev_for_scripts是去尋找SD卡boot分區裡面是否有boot.scr.uimg和boot.scr檔案，假如有的話就會執行boot_a_script
scan_dev_for_scripts=
for script in ${boot_scripts};
do
if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${script}; then # mmc 0:4 (/boot.scr.uimg /boot.scr /boot/boot.scr.uimg /boot/boot.scr)
echo Found U-Boot script ${prefix}${script};
run boot_a_script;
echo SCRIPT FAILED: continuing...;
fi;
done
boot_a_script=
load ${devtype} ${devnum}:${distro_bootpart} ${scriptaddr} ${prefix}${script}; source ${scriptaddr}
---> load mmc 0:4 0xc4100000 (/boot.scr.uimg /boot.scr /boot/boot.scr.uimg /boot/boot.scr)
---> source 0xc4100000
boot.scr.uimg 是一個script， st 在yocto裡有說明boot.scr.uimg可以用mkimage來編譯出來。但通常會自己生成，這部份我們不用自己做。
他的流程大概如下:
memory@80000000 {
device_type = "memory";
reg = <0x0 0x80000000 0x0 0x80000000>;
};
舉個例子，如果說你想要在這邊使用某個 button 的功能，那可以像下方這樣去做設定。
/*
gpio-keys {
compatible = "gpio-keys";
button-user-1 {
label = "User-1";
linux,code = <BTN_1>;
gpios = <&gpiod 5 GPIO_ACTIVE_HIGH>;
status = "okay";
};
button-user-2 {
label = "User-2";
linux,code = <BTN_2>;
gpios = <&gpiog 2 GPIO_ACTIVE_HIGH>;
status = "okay";
};
button-wake-up {
label = "wake-up";
linux,code = <KEY_WAKEUP>;
interrupts-extended = <&optee 0>;
status = "okay";
};
}; */
在當中的gpios就可以去修改為對應的腳位。
以及 GPIO_ACTIVE_HIGH 或者是 GPIO_ACTIVE_LOW，當我們設定成 GPIO_ACTIVE_HIGH 表示在高電位的時候觸發他的功能 (高電位有效)，相反的 GPIO_ACTIVE_LOW 也就是低電位有效。
接著與啟動息息相關的就是 SD 卡與 emmc ， 我們可以在設備樹當中找到 sdemmc1 , sdemmc1 。 分別對應的會是 SD 卡與 emmc ， 假如想要修改的話可以找到像下方的段落，按照對應的屬性去修改。這邊推薦可以看看 ST 官方的 develop package ， 當中會有非常多的 yaml檔用來說明dts的屬性有哪些，以及該如何用。
&sdmmc1 {
pinctrl-names = "default", "opendrain", "sleep";
pinctrl-0 = <&sdmmc1_b4_pins_a>;
pinctrl-1 = <&sdmmc1_b4_od_pins_a>;
pinctrl-2 = <&sdmmc1_b4_sleep_pins_a>;
cd-gpios = <&gpiof 4 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
disable-wp;
st,neg-edge;
bus-width = <4>;
vmmc-supply = <&scmi_vdd_sdcard>;
vqmmc-supply = <&scmi_vddio1>;
sd-uhs-sdr12;
sd-uhs-sdr25;
sd-uhs-sdr50;
sd-uhs-ddr50;
sd-uhs-sdr104;
status = "okay";
};
git add . && git commit -m "test"
devtool finish u-boot-stm32mp /home/ubuntu/stm32mp1/layers/meta-custom # 依照個人修改
bitbake u-boot-stm32mp
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