一、引言
本文整体介绍RK所提供的SDK中，系统整体的启动流程，包含以下三部分
1、boot启动，即MiniLoaderAll.bin和uboot.img启动
2、linux内核启动，即kernel.img的启动
3、android系统的启动，即ramdisk.img、system.img的启动。
本文先来介绍第一部分
二、U-boot配置(详细过程可看我上一篇文章)
1、工具链配置：
Rockchip U-Boot 默认使用 Google Android 系统提供的 GCC ToolChain，在 “U-BOOT/Makefile” 中指定
2、平台配置
平台配置文件位于"U-Boot/configs"目录下 (为rk322xh_box_defconfig)
其中Rockchip相关的以RK开头，并根据产品形态分为 MID 和 BOX 两种配置，Rockchip 芯片平台的配置
主要是芯片类型，Rockchip 一些 Kconfig 的关键配置，采用savedefconfig 模式保存。该选项内的配置会被优先编译成宏定义并在相关的项前面自动添加 CONFIG_，可以在U-BOOT 自动生成的配置文（include/config.h）中看到生成的宏定义，会优先系统的配置文件，可以支配系统的配置文件。
3、系统配置
位于 U-Boot 根目录下的 include\configs 文件夹下，同样以 RK 开头(为rk33plat.h)
平台的配置，根据不同芯片进行一些细节的配置，如内存地址、简配一些功能模块的配置
整体流程
执行
make rk3368_defconfig
make ARCHV=aarch64
会在rk3368_defconfig配置文件中选择芯片系列，生成include/config.h，如下
* Automatically generated - do not edit */
#define CONFIG_RKCHIP_RK322XH 1
#define CONFIG_PRODUCT_BOX 1
#define CONFIG_NORMAL_WORLD 1
#define CONFIG_SECOND_LEVEL_BOOTLOADER 1
#define CONFIG_BAUDRATE 115200
#define CONFIG_BOARDDIR board/rockchip/rk33xx
#include <config_defaults.h>
#include <configs/rk33plat.h>
#include <asm/config.h>
#include <config_fallbacks.h>
#include <config_uncmd_spl.h>
在该文件中调用rk33plat.h 系统配置文件，设置一系列配置。
三、UBOOT启动分析
程序启动是从u-boot/arch/arm/cpu/armv7目录下的start.S文件开始，里面会调用到该目录下的/rk32xx/lowlevel_init.S文件，start.S函数最后调用_main函数，这个在u-boot/arch/arm/lib/crt0.S文件中，里面再调用board_init_f和board_init_r函数，其定义均在u-boot/arch/arm/lib/board.c文件中。
1、board_init_f函数会调用初始化队列里面的函数，如下定义：
ENTRY(_main)
/*
* Set up initial C runtime environment and call board_init_f(0).
*/
#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
ldr sp, =(CONFIG_SPL_STACK)
#else
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
#endif
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
mov r2, sp
sub sp, sp, #GD_SIZE /* allocate one GD above SP */
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
mov r9, sp /* GD is above SP */
mov r1, sp
mov r0, #0
clr_gd:
cmp r1, r2 /* while not at end of GD */
strlo r0, [r1] /* clear 32-bit GD word */
addlo r1, r1, #4 /* move to next */
blo clr_gd
#if defined(CONFIG_SYS_MALLOC_F_LEN) && !defined(CONFIG_SPL_BUILD)
sub sp, sp, #CONFIG_SYS_MALLOC_F_LEN
str sp, [r9, #GD_MALLOC_BASE]
#endif
/* mov r0, #0 not needed due to above code */
bl board_init_f
init_fnc_t *init_sequence[] = {
arch_cpu_init, /* basic arch cpu dependent setup */
mark_bootstage,
#ifdef CONFIG_OF_CONTROL
fdtdec_check_fdt,
#endif
#if defined(CONFIG_BOARD_EARLY_INIT_F)
board_early_init_f,
#endif
timer_init, /* initialize timer */
#ifdef CONFIG_BOARD_POSTCLK_INIT
board_postclk_init,
#endif
#ifdef CONFIG_FSL_ESDHC
get_clocks,
#endif
env_init, /* 设置gd的成员，初始化环境变量 */
init_baudrate, /* 设置波特率 */
serial_init, /* 初始化串口 */
console_init_f, /* 完成第一阶段的控制台初始化 */
display_banner, /* say that we are here */
print_cpuinfo, /* 打印uboot时钟频率信息 */
#if defined(CONFIG_DISPLAY_BOARDINFO)
checkboard, /* display board info */
#endif
#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SYS_I2C)
init_func_i2c,
#endif
dram_init, /* 设置gd->ram_size */
NULL,
};
board_init_r
最后会执行board_init_r 函数，进入uboot命令行，等待输入命令，若无命令输入，则启动内核
下为crt0.S中(_main)的最后一段
/* Set up final (full) environment */
bl c_runtime_cpu_setup /* we still call old routine here */
ldr r0, =__bss_start /* this is auto-relocated! */
ldr r1, =__bss_end /* this is auto-relocated! */
mov r2, #0x00000000 /* prepare zero to clear BSS */
clbss_l:cmp r0, r1 /* while not at end of BSS */
strlo r2, [r0] /* clear 32-bit BSS word */
addlo r0, r0, #4 /* move to next */
blo clbss_l
bl coloured_LED_init
bl red_led_on
/* call board_init_r(gd_t *id, ulong dest_addr) */
mov r0, r9 /* gd_t */
ldr r1, [r9, #GD_RELOCADDR] /* dest_addr */
/* call board_init_r */
ldr pc, =board_init_r /* this is auto-relocated! */
/* we should not return here. */
board_init_r
void board_init_r(gd_t *id, ulong dest_addr)
{
ulong malloc_start;
#if !defined(CONFIG_SYS_NO_FLASH)
ulong flash_size;
#endif
gd->flags |= GD_FLG_RELOC; /* tell others: relocation done */
bootstage_mark_name(BOOTSTAGE_ID_START_UBOOT_R, "board_init_r");
monitor_flash_len = (ulong)&__rel_dyn_end - (ulong)_start;
/* Enable caches */
enable_caches();
debug("monitor flash len: %08lX\n", monitor_flash_len);
board_init(); /* Setup chipselects */
/*
* TODO: printing of the clock inforamtion of the board is now
* implemented as part of bdinfo command. Currently only support for
* davinci SOC's is added. Remove this check once all the board
* implement this.
*/
#ifdef CONFIG_CLOCKS
set_cpu_clk_info(); /* Setup clock information */
#endif
serial_initialize();
#ifndef CONFIG_SKIP_RELOCATE_UBOOT
debug("Now running in RAM - U-Boot at: %08lx\n", dest_addr);
#else
debug("Now running in RAM - U-Boot at: %08lx\n", CONFIG_SYS_SDRAM_BASE);
#endif
#ifdef CONFIG_LOGBUFFER
logbuff_init_ptrs();
#endif
#ifdef CONFIG_POST
post_output_backlog();
#endif
/* The Malloc area is immediately below the monitor copy in DRAM */
malloc_start = dest_addr - TOTAL_MALLOC_LEN;
mem_malloc_init (malloc_start, TOTAL_MALLOC_LEN);
#ifdef CONFIG_ARCH_EARLY_INIT_R
arch_early_init_r();
#endif
power_init_board();
#if !defined(CONFIG_SYS_NO_FLASH)
puts("Flash: ");
flash_size = flash_init();
if (flash_size > 0) {
# ifdef CONFIG_SYS_FLASH_CHECKSUM
print_size(flash_size, "");
/*
* Compute and print flash CRC if flashchecksum is set to 'y'
*
* NOTE: Maybe we should add some WATCHDOG_RESET()? XXX
*/
if (getenv_yesno("flashchecksum") == 1) {
printf(" CRC: %08X", crc32(0,
(const unsigned char *) CONFIG_SYS_FLASH_BASE,
flash_size));
}
putc('\n');
# else /* !CONFIG_SYS_FLASH_CHECKSUM */
print_size(flash_size, "\n");
# endif /* CONFIG_SYS_FLASH_CHECKSUM */
} else {
puts(failed);
hang();
}
#endif
#if defined(CONFIG_CMD_NAND)
puts("NAND: ");
nand_init(); /* go init the NAND */
#endif
#if defined(CONFIG_CMD_ONENAND)
onenand_init();
#endif
#ifdef CONFIG_GENERIC_MMC
puts("MMC: ");
mmc_initialize(gd->bd);
#endif
#ifdef CONFIG_ROCKCHIP
board_storage_init();
#endif
#ifdef CONFIG_CMD_SCSI
puts("SCSI: ");
scsi_init();
#endif
#ifdef CONFIG_HAS_DATAFLASH
AT91F_DataflashInit();
dataflash_print_info();
#endif
/* initialize environment */
if (should_load_env())
env_relocate();
else
set_default_env(NULL);
#if defined(CONFIG_CMD_PCI) || defined(CONFIG_PCI)
arm_pci_init();
#endif
stdio_init(); /* get the devices list going. */
jumptable_init();
#if defined(CONFIG_API)
/* Initialize API */
api_init();
#endif
console_init_r(); /* fully init console as a device */
#ifdef CONFIG_DISPLAY_BOARDINFO_LATE
# ifdef CONFIG_OF_CONTROL
/* Put this here so it appears on the LCD, now it is ready */
display_fdt_model(gd->fdt_blob);
# else
checkboard();
# endif
#endif
#if defined(CONFIG_ARCH_MISC_INIT)
/* miscellaneous arch dependent initialisations */
arch_misc_init();
#endif
#if defined(CONFIG_MISC_INIT_R)
/* miscellaneous platform dependent initialisations */
misc_init_r();
#endif
#ifndef CONFIG_ROCKCHIP
/* set up exceptions */
interrupt_init();
/* enable exceptions */
enable_interrupts();
#endif
/* Initialize from environment */
load_addr = getenv_ulong("loadaddr", 16, load_addr);
#ifdef CONFIG_BOARD_LATE_INIT
board_late_init();
#endif
#ifdef CONFIG_BITBANGMII
bb_miiphy_init();
#endif
#if defined(CONFIG_CMD_NET)
puts("Net: ");
eth_initialize(gd->bd);
#if defined(CONFIG_RESET_PHY_R)
debug("Reset Ethernet PHY\n");
reset_phy();
#endif
#endif
#ifdef CONFIG_POST
post_run(NULL, POST_RAM | post_bootmode_get(0));
#endif
#if defined(CONFIG_PRAM) || defined(CONFIG_LOGBUFFER)
/*
* Export available size of memory for Linux,
* taking into account the protected RAM at top of memory
*/
{
ulong pram = 0;
uchar memsz[32];
#ifdef CONFIG_PRAM
pram = getenv_ulong("pram", 10, CONFIG_PRAM);
#endif
#ifdef CONFIG_LOGBUFFER
#ifndef CONFIG_ALT_LB_ADDR
/* Also take the logbuffer into account (pram is in kB) */
pram += (LOGBUFF_LEN + LOGBUFF_OVERHEAD) / 1024;
#endif
#endif
sprintf((char *)memsz, "%ldk", (gd->ram_size / 1024) - pram);
setenv("mem", (char *)memsz);
}
#endif
/* main_loop() can return to retry autoboot, if so just run it again. */
for (;;) {
main_loop();
}
/* NOTREACHED - no way out of command loop except booting */
}
board_init_r函数里调用了board_init和board_late_init函数，其均定义在u-boot/board/rockchip/rk32xx/rk32xx.c文件：
int board_init(void)
{
/* Set Initial global variables */
gd->bd->bi_arch_number = MACH_TYPE_RK30XX;
gd->bd->bi_boot_params = PHYS_SDRAM_1 + 0x88000;
return 0;
}
int board_late_init(void)
{
debug("board_late_init\n");
load_disk_partitions();
prepare_fdt();
key_init();
#ifdef CONFIG_POWER_RK
pmic_init(0);
fg_init(0); /*fuel gauge init*/
#endif
SecureBootCheck();
//TODO:set those buffers in a better way, and use malloc?
setup_space(gd->arch.rk_extra_buf_addr);
/* after setup space, get id block data first */
get_idblk_data();
if (get_bootloader_ver() == 0) {
printf("\n#Boot ver: %s\n", bootloader_ver);
}
char tmp_buf[30];
if (getSn(tmp_buf)) {
tmp_buf[sizeof(tmp_buf)-1] = 0;
setenv("fbt_sn#", tmp_buf);
}
#ifdef CONFIG_CMD_FASTBOOT
fbt_preboot();
#else
rk_preboot();
#endif
return 0;
}
可见board_late_init函数里完成开发板按键等功能的初始化，key_init()函数在u-boot/board/rockchip/common/rkloader目录下的key.c文件中实现：
void key_init(void)
{
#if (CONFIG_RKCHIPTYPE == CONFIG_RK3036)
RockusbKeyInit(&key_rockusb);
RemotectlInit();
#else
charge_state_gpio.name = "charge_state";
charge_state_gpio.flags = 0;
charge_state_gpio.gpio = ((GPIO_BANK0 << RK_GPIO_BANK_OFFSET) | GPIO_B0);
gpio_direction_input(charge_state_gpio.gpio);
//power_hold_gpio.name
RockusbKeyInit(&key_rockusb);
FastbootKeyInit(&key_fastboot);
RecoveryKeyInit(&key_recovery);
PowerKeyInit();
#endif
}
该文件中还实现按键检测函数checkKey()：
int checkKey(uint32* boot_rockusb, uint32* boot_recovery, uint32* boot_fastboot)
{
*boot_rockusb = 0;
*boot_recovery = 0;
*boot_fastboot = 0;
printf("checkKey\n");
if(GetPortState(&key_rockusb))
{
*boot_rockusb = 1;
//printf("rockusb key is pressed\n");
}
if(GetPortState(&key_recovery))
{
*boot_recovery = 1;
//printf("recovery key is pressed\n");
}
if(GetPortState(&key_fastboot))
{
*boot_fastboot = 1;
//printf("fastboot key is pressed\n");
}
return 0;
}
系统上电时对于recovery按键的识别就在这个函数中。
来源：CSDN
作者：文艺小少年
链接：https://blog.csdn.net/weixin_38019025/article/details/104192849