arch/arm/mach-zynq/slcr.c 通过电阻跳线在寄存器读出启动 bootstrap 状态:
u32 zynq_slcr_get_boot_mode(void)
{
/* Get the bootmode register value */
return readl(&slcr_base->boot_mode);
}
board/xilinx/zynq/board.c 根据读到的启动选项设置环境变量 modeboot:
int board_late_init(void)
{
switch ((zynq_slcr_get_boot_mode()) & ZYNQ_BM_MASK) {
case ZYNQ_BM_NOR:
setenv("modeboot", "norboot");
break;
case ZYNQ_BM_SD:
setenv("modeboot", "sdboot");
break;
case ZYNQ_BM_JTAG:
setenv("modeboot", "jtagboot");
break;
default:
setenv("modeboot", "");
break;
}
return 0;
}
include/configs/zynq-common.h 启动环境变量 preboot
/* enable preboot to be loaded before CONFIG_BOOTDELAY */
#define CONFIG_PREBOOT
include/configs/zynq-common.h 设置其他环境变量, 启动入口是 preboot 这个脚本:
/* Default environment */
#ifndef CONFIG_EXTRA_ENV_SETTINGS
#define CONFIG_EXTRA_ENV_SETTINGS \
"fit_image=fit.itb\0" \
"load_addr=0x2000000\0" \
"fit_size=0x800000\0" \
"flash_off=0x100000\0" \
"nor_flash_off=0xE2100000\0" \
"fdt_high=0x20000000\0" \
"initrd_high=0x20000000\0" \
"loadbootenv_addr=0x2000000\0" \
"bootenv=uEnv.txt\0" \
"bootenv_dev=mmc\0" \
"loadbootenv=load ${bootenv_dev} 0 ${loadbootenv_addr} ${bootenv}\0" \
"importbootenv=echo Importing environment from ${bootenv_dev} ...; " \
"env import -t ${loadbootenv_addr} $filesize\0" \
"bootenv_existence_test=test -e ${bootenv_dev} 0 /${bootenv}\0" \
"setbootenv=if env run bootenv_existence_test; then " \
"if env run loadbootenv; then " \
"env run importbootenv; " \
"fi; " \
"fi; \0" \
"sd_loadbootenv=set bootenv_dev mmc && " \
"run setbootenv \0" \
"usb_loadbootenv=set bootenv_dev usb && usb start && run setbootenv \0" \
"preboot=if test $modeboot = sdboot; then " \
"run sd_loadbootenv; " \
"echo Checking if uenvcmd is set ...; " \
"if test -n $uenvcmd; then " \
"echo Running uenvcmd ...; " \
"run uenvcmd; " \
"fi; " \
"fi; \0" \
"norboot=echo Copying FIT from NOR flash to RAM... && " \
"cp.b ${nor_flash_off} ${load_addr} ${fit_size} && " \
"bootm ${load_addr}\0" \
"sdboot=echo Copying FIT from SD to RAM... && " \
"load mmc 0 ${load_addr} ${fit_image} && " \
"bootm ${load_addr}\0" \
"jtagboot=echo TFTPing FIT to RAM... && " \
"tftpboot ${load_addr} ${fit_image} && " \
"bootm ${load_addr}\0" \
"usbboot=if usb start; then " \
"echo Copying FIT from USB to RAM... && " \
"load usb 0 ${load_addr} ${fit_image} && " \
"bootm ${load_addr}; fi\0" \
DFU_ALT_INFO
#endif
离线
参考这个帖子: https://whycan.cn/t_2297.html
上面有脚本检测到是 sdboot (sd卡启动) 读 首分区的 uEnv.txt, 然后再把这个文件 env import 到到环境变量中去, 完成了从 uEnv.txt 环境配置。
离线
楼主研究的真深 支持下
离线