Am335x u-boot 代码大概流程
在_面之前的流程和u-boot-spl一样，区别在于_main中。
对于u-boot 2016.03来说
ENTRY(_main)
/*
* Set up initial C runtime environment and call board_init_f(0).
*/
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
#endif
mov r0, sp
bl board_init_f_alloc_reserve
mov sp, r0
/* set up gd here, outside any C code */
mov r9, r0
bl board_init_f_init_reserve
mov r0, #0
bl board_init_f
ldr sp, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
#endif
ldr r9, [r9, #GD_BD] /* r9 = gd->bd */
sub r9, r9, #GD_SIZE /* new GD is below bd */
adr lr, here
ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */
add lr, lr, r0
ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
b relocate_code
here:
/*
* now relocate vectors
*/
bl relocate_vectors
/* 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 r3, =__bss_end /* this is auto-relocated! */
mov r1, #0x00000000 /* prepare zero to clear BSS */
subs r2, r3, r0 /* r2 = memset len */
bl memset
/* 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. */
#endif
ENDPROC(_main)
对于函数board_init_f （u-boot-2016.03/common/board_f.c）
1 、计算u-boot镜像的长度
2、内存池的设置
3、控制台log缓存
4、CPU的特殊初始化
5、初始化定时器 ..../arch/arm/cpu/armv7/omap-common/timer.c
6、环境变量初始化
7、a、波特路初始化
b、串口初始化 .../driver/serival/serival-unclass.c
c、控制台初始化 // 可放在板级初始化board_init_f（spl）内，方便调试用
8、打印相关选择项
9、打印CPU信息---speed
10、 a、说明要初始化的dram ../arch/arm/cpu/armv7/am33xx/emif4.c
b、对relcoate 区域规划
c、relcoate 之后 gd成员设置
11、define选择，如果定义了硬件
I2C、SPI，对其进行初始化 u-boot-2016.03/common/board_f.c
对于函数board_init_f （u-boot-2016.03/common/board_r.c）
具体参看此博文
在_面之前的流程和u-boot-spl一样，区别在于_main中。
对于u-boot 2016.03来说
ENTRY(_main)
/*
* Set up initial C runtime environment and call board_init_f(0).
*/
ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
#endif
mov r0, sp
bl board_init_f_alloc_reserve
mov sp, r0
/* set up gd here, outside any C code */
mov r9, r0
bl board_init_f_init_reserve
mov r0, #0
bl board_init_f
ldr sp, [r9, #GD_START_ADDR_SP] /* sp = gd->start_addr_sp */
bic sp, sp, #7 /* 8-byte alignment for ABI compliance */
#endif
ldr r9, [r9, #GD_BD] /* r9 = gd->bd */
sub r9, r9, #GD_SIZE /* new GD is below bd */
adr lr, here
ldr r0, [r9, #GD_RELOC_OFF] /* r0 = gd->reloc_off */
add lr, lr, r0
ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
b relocate_code
here:
/*
* now relocate vectors
*/
bl relocate_vectors
/* 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 r3, =__bss_end /* this is auto-relocated! */
mov r1, #0x00000000 /* prepare zero to clear BSS */
subs r2, r3, r0 /* r2 = memset len */
bl memset
/* 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. */
#endif
ENDPROC(_main)
对于函数board_init_f （u-boot-2016.03/common/board_f.c）
1 、计算u-boot镜像的长度
2、内存池的设置
3、控制台log缓存
4、CPU的特殊初始化
5、初始化定时器 ..../arch/arm/cpu/armv7/omap-common/timer.c
6、环境变量初始化
7、a、波特路初始化
b、串口初始化 .../driver/serival/serival-unclass.c
c、控制台初始化 // 可放在板级初始化board_init_f（spl）内，方便调试用
8、打印相关选择项
9、打印CPU信息---speed
10、 a、说明要初始化的dram ../arch/arm/cpu/armv7/am33xx/emif4.c
b、对relcoate 区域规划
c、relcoate 之后 gd成员设置
11、define选择，如果定义了硬件
I2C、SPI，对其进行初始化 u-boot-2016.03/common/board_f.c
对于函数board_init_f （u-boot-2016.03/common/board_r.c）
具体参看此博文