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设计原理图：

引脚说明：

1、主要初始化函数位置：

/ptboce/bootable/bootloader/lk/target/M9PLUS_10/init.c

#include 
   
    #define TLMM_VOL_UP_BTN_GPIO    107/* Return 1 if vol_up pressed */int target_volume_up()    //按键上初始化代码{    uint8_t status = 0;    gpio_tlmm_config(TLMM_VOL_UP_BTN_GPIO, 0, GPIO_INPUT, GPIO_PULL_UP, GPIO_2MA, GPIO_ENABLE);    /* Wait for the gpio config to take effect - debounce time */    thread_sleep(10);    /* Get status of GPIO */    status = gpio_status(TLMM_VOL_UP_BTN_GPIO);    /* Active low signal. */    return !status;}/* Return 1 if vol_down pressed */uint32_t target_volume_down() //按键下初始化代码{    /* Volume down button tied in with PMIC RESIN. */    return pm8x41_resin_status();}#if FEATURE_HS_BOOT_SYSTEM_HS/* Return 1 if pwr pressed */uint32_t target_pwr_key() //开关按键初始化代码{    /* Volume down button tied in with PMIC RESIN. */    return pm8x41_get_pwrkey_is_pressed();}#endifstatic void target_keystatus()  //按键总初始化代码{    keys_init();    if(target_volume_down())        keys_post_event(KEY_VOLUMEDOWN, 1);    if(target_volume_up())        keys_post_event(KEY_VOLUMEUP, 1);#if FEATURE_HS_BOOT_SYSTEM_HS    if(target_pwr_key())        keys_post_event(KEY_PWR, 1);#endif}
   

次要代码：

/ptboce/bootable/bootloader/lk/dev/keys/keys.c

static unsigned long key_bitmap[BITMAP_NUM_WORDS(MAX_KEYS)];void keys_init(void){    memset(key_bitmap, 0, sizeof(key_bitmap));}

从初始化代码上看，开关按键和音量下键是M9源码中默认的，不需要去重新定义和配置，直接调用封装好的函数初始化就好了。二音量上键，需要定义一下（GPIO107），并初始化。

2、主要外部调用函数

/bootable/bootloader/lk/dev/pmic/pm8916/pm8916.c

/bootable/bootloader/lk/dev/pmic/pm8916/include/pm8916.h

uint8_t pm_get_power_on_status(void)uint32_t pm_get_chg_voltage()

参考学习：