最近在做一个平台优化系统启动时间的任务,然后根据硬件BLOCK图以及端子配置表,选了一个测试端子,GPIO10,来量测系统时间,uboot 中加了如下代码作为uboot 启动时间点开始代码如下,uboot 启动开始点在start.s中,实现代码 如下: — a/arch/arm/cpu/armv7/start.S +++ b/arch/arm/cpu/armv7/start.S @@ -127,7 +127,7 @@ switch_to_hypervisor_ret: b _do_nonsec_entry 3: @ No STR boot #endif -
bl _gpio_test bl _main — a/common/board_f.c +++ b/common/board_f.c @@ -1073,8 +1073,16 @@ static const init_fnc_t init_sequence_f[] = { NULL, };+#define STA_GPIO0_BASE_TEST 0x48120000 + +void _gpio_test() +{
writel((1 << 10), STA_GPIO0_BASE_TEST + 0x14);//set GPIO_DIRSwritel((1 << 10), STA_GPIO0_BASE_TEST + 0x04);//set GPIO_DATAS +} void board_init_f(ulong boot_flags) {/GPIO_TEST();/ #ifdef CONFIG_SYS_GENERIC_GLOBAL_DATAkernel 中本来打算等GPIO 初始化完了,在init 进程开始前拉一段GPIO,但是考虑到kernel 初始化部分可能也需要占时间,于是在head.s 中加入了一段汇编代码,本来对汇编不熟悉,现学些了下,结果对照datasheet GPIO 的配置,最后设置成功了以此记录下问题,汇编代码如下: diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S index fc6d541549a2…9a81ecc0ff80 100644 — a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -543,6 +543,17 @@ not_relocated: mov r0, #0 mov r1, sp @ malloc space above stack add r2, sp, #0x10000 @ 64k max mov r3, r7 +
ldr r11, =0x48120014 //配置DIR地址 ldr r12,[r11] //读DIR值 orr r12,r12,#0x00000400 //读取值或0x400 str r12, [r11] //设置值写会DIR ldr r11, =0x48120008 //DAT设置同上面 ldr r12,[r11] orr r12,r12,#0x00000400 str r12, [r11] bl decompress_kernel bl cache_clean_flush bl cache_off