【高通SDM660平台 Android 10.0】(22) --- Flashlight 及 Kernel Flashlight 代码分析

发布日期：2021-06-29 14:52:19 浏览次数：2 分类：技术文章

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【高通SDM660平台 Android 10.0】22 --- Flashlight 及 Kernel Flashlight 代码分析

原创文章列表：

《》

一、[硬件] 闪光灯硬件原理图

本文以 mm-camera/mm-camera2/media-controller/modules/sensors/configs/sdm660_camera.xml 中的flash 为例，

先来看下原理图：

从原理图中可以看出，闪光灯的电 VDD_FLASH 及开关控制引脚 FLASH_STROBE、FLASH_LED1、FLASH_LED2、FLASH_LED3 都是由 PM660L 来控制的。

其中：

VDD_FLASH ：是主供电

FLASH_STROBE ：手电筒模式时的PWM输出脚

FLASH_LED1、FLASH_LED2、FLASH_LED3 ：闪光灯模式时的PWM输出脚，可以包含单闪、双闪需求

这个是一个方框图，由电池供电，经过升压，接着通过脉宽引脚的高电平来控制LED 的亮暗程度。。

所以整个原理是比较清晰的，代码方面要需对上述引脚做如下控制

闪光灯的上下电

手电筒模式还是闪光灯模式

根据亮度来控制PWM 输出的高电平脉宽占比

二、[vendor] 库文件 lib

从sdm660_camera.xml 中可以看出，<FlashName>pmic</FlashName>，

其代码位于：mm-camera/mm-camera2/media-controller/modules/sensors/flash/libs/pmic/pmic_flash.h，最终编译生成 libflash_pmic.so 库

在其头文件中：

# mm-camera/mm-camera2/media-controller/modules/sensors/flash/libs/pmic/pmic_flash.h#include "flash_lib.h"/* * if flash_driver_type is set to FLASH_DRIVER_DEFAULT * flash specifications are taken from kernel and the flash is driven by kernel. * For other value FLASH_DRIVER_PMIC / FLASH_DRIVER_GPIO * FLASH_DRIVER_I2C all the information like max current * max duration and num of flashes must be provided in this driver. */static flash_lib_t flash_lib_ptr = {
     .flash_name = "pmic",  .flash_driver_type = FLASH_DRIVER_TYPE_DEFAULT,  .main_flash_on_frame_skip = 3,  .main_flash_off_frame_skip = 3,  .torch_on_frame_skip = 2,  .torch_off_frame_skip = 2,};

头文件中主要是定义了在闪光灯打开时，摄像头需要跳过的帧数，及在手机筒打开时需要跳过的帧数。

还是一个比较重要的就是 flash_driver_type，

当 .flash_driver_type = FLASH_DRIVER_TYPE_DEFAULT, 时，闪光灯的相关配置是由kernel 来定义的。

当 .flash_driver_type = FLASH_DRIVER_PMIC, 和其他值时，闪光灯的相关配置需要由本lib 库来定义。

三、[vendor] 通用代码 flash.c 初始化

在前在《》中，我们分析过了，

flash open动作是在 module_sensor_offload_open()中调用打开闪光灯节点的。

flash 初始化是由 module_sensor_offload_init_config() 中来调用的。

void module_sensor_offload_init_config( void* param1,  void* param2,  void* param3 __attribute__((unused)),  					void* param4 __attribute__((unused))){
     // 初始化闪光灯 ，调用 flash_init(),打开闪光灯 lib 库  SLOW("flash subdev id = %d",  status = module_sensor_flash_init(s_bundle);    // 获取使用闪光灯时，跳过的帧数，如果没设置，默认过滤 2 帧  /* Get led frame skip timing parameters */  SENSOR_SUB_MODULE_PROCESS_EVENT(s_bundle, SUB_MODULE_LED_FLASH, LED_FLASH_GET_FRAME_SKIP_TIME_PARAMS, s_bundle, rc);  if (rc < 0) {
       SERR("failed to get led off frame skip time");    s_bundle->main_flash_on_frame_skip = 2;    s_bundle->main_flash_off_frame_skip = 2;    s_bundle->torch_on_frame_skip = 2;    s_bundle->torch_off_frame_skip = 2;  }}

3.1 module_sensor_flash_init()

# mm-camera/mm-camera2/media-controller/modules/sensors/module/module_sensor.cboolean module_sensor_flash_init(module_sensor_bundle_info_t *s_bundle){
     /* Get flash name from camera config read from daemon init */  a_name = s_bundle->sensor_common_info.camera_config.flash_name;  SENSOR_SUB_MODULE_PROCESS_EVENT(s_bundle, SUB_MODULE_LED_FLASH, LED_FLASH_INIT, a_name, rc);  return TRUE;}

可以看出，在 module_sensor_flash_init() 中主要是调用 flash_init() 来做初始化的。

case LED_FLASH_INIT:    rc = flash_init(flash_ctrl, data);    goto flash_process_Exit;

我们来看下 flash_init() 的内容。

根据传递的name ，拼凑lib 库的字符串，此处为 libflash_pmic.so，同步将 pmic_flash.h中的结构体内容保存在 flash_ptr->driver_lib_data 中。

解析 pmic 参数信息，及 flash_driver_type 信息。

配置 I2C 地址信息

解析上下电信息，准备下发到 Kernel 中

下发 CFG_FLASH_INIT 命令到 Kernel 中，相关信息保存在 .flash_init_info 中

static int32_t flash_init(void *ptr, void *data){
     sensor_flash_data_t *flash_ctrl = (sensor_flash_data_t*)ptr;  struct msm_flash_init_info_t flash_init_info;  struct msm_flash_cfg_data_t flash_cfg;  struct msm_camera_i2c_reg_setting_array *flash_init_settings = NULL;  struct msm_sensor_power_setting_array *power_setting_array = NULL;  SDBG("Enter");  /* memset flash init info */  memset(&flash_init_info, 0, sizeof(flash_init_info));  // 1. 根据传递的name ，拼凑lib 库的字符串，此处为 libflash_pmic.so，同步将 pmic_flash.h中的结构体内容保存在 flash_ptr->driver_lib_data 中  /* Load flash library */  rc = flash_load_lib(ptr, name);  // 2. 解析 pmic 参数信息。  flash_update_settings_size(flash_ctrl->driver_lib_data);  // 3. 解析 flash_driver_type 信息  switch (flash_ctrl->driver_lib_data->flash_driver_type) {
       case FLASH_DRIVER_TYPE_PMIC:        flash_init_info.flash_driver_type = FLASH_DRIVER_PMIC;        break;    case FLASH_DRIVER_TYPE_I2C:        flash_init_info.flash_driver_type = FLASH_DRIVER_I2C;        break;    case FLASH_DRIVER_TYPE_GPIO:        flash_init_info.flash_driver_type = FLASH_DRIVER_GPIO;        break;    case FLASH_DRIVER_TYPE_DEFAULT:        flash_init_info.flash_driver_type = FLASH_DRIVER_DEFAULT;        break;  }  // 4. 配置I2C 地址  flash_init_info.slave_addr = flash_ctrl->driver_lib_data->i2c_flash_info.slave_addr;  flash_init_info.i2c_freq_mode = sensor_sdk_util_get_i2c_freq_mode(    			flash_ctrl->driver_lib_data->i2c_flash_info.i2c_freq_mode);    			  // 5. 解析上下电信息，准备下发到 Kernel 中  /* Translate power settings from uspace structure to kernel struct */  power_setting_array = (struct msm_sensor_power_setting_array *)malloc(sizeof(*power_setting_array));  translate_camera_power_setting(power_setting_array,&(flash_ctrl->driver_lib_data->power_setting_array));  /* Translate reg array settings from uspace structure to kernel struct */  flash_init_settings = (struct msm_camera_i2c_reg_setting_array *)malloc(sizeof(*flash_init_settings));  translate_sensor_reg_setting_array(flash_init_settings,   			 &(flash_ctrl->driver_lib_data->i2c_flash_info.flash_init_settings));  flash_init_info.power_setting_array = power_setting_array;  flash_init_info.settings = flash_init_settings;  for (i = 0; i < MAX_LED_TRIGGERS; i++) {
       flash_cfg.flash_current[i] = flash_ctrl->driver_lib_data->max_flash_current[i];    flash_cfg.flash_duration[i] = flash_ctrl->driver_lib_data->max_flash_duration[i];    SLOW("i = %d flash_current = %d flash_duration = %d", i, flash_cfg.flash_current[i], flash_cfg.flash_duration[i]);  }  // 6. 下发 CFG_FLASH_INIT 命令到 Kernel 中，相关信息保存在 .flash_init_info 中  flash_cfg.cfg_type = CFG_FLASH_INIT;  flash_cfg.cfg.flash_init_info = &flash_init_info;  rc = ioctl(flash_ctrl->fd, VIDIOC_MSM_FLASH_CFG, &flash_cfg);  for (i = 0; i < MAX_LED_TRIGGERS; i++) {
       flash_ctrl->flash_max_current[i] = flash_cfg.flash_current[i];    flash_ctrl->flash_max_duration[i] = flash_cfg.flash_duration[i];    SLOW("i = %d flash_max_current = %d flash_max_duration = %d",      			i, flash_ctrl->flash_max_current[i], flash_ctrl->flash_max_duration[i]);  }  SDBG("Exit");  free(power_setting_array);  free(flash_init_settings);  return SENSOR_SUCCESS;}

3.2 flash_process()

flash_process() 是 flashlight 的核心函数

# mm-camera/mm-camera2/media-controller/modules/sensors/flash/module/flash.cstatic int32_t flash_process(void *ctrl, sensor_submodule_event_type_t event, void *data){
     flash_ctrl = (sensor_flash_data_t *)ctrl;  rer = flash_ctrl->rer;  dual_led_setting = &flash_ctrl->dual_led_setting;  /* Initilize to invalid value   * Kernel uses default values if not updated */  cfg.flash_current[0] = default_current;  cfg.flash_current[1] = default_current;  /* Translate reg array settings from uspace structure to kernel struct */  flash_settings = (struct msm_camera_i2c_reg_setting_array *)malloc( sizeof(*flash_settings));  SLOW("event %d", event);  switch (event) {
     case LED_FLASH_GET_MAX_CURRENT: {
   				// 1. 获得闪光灯的最大电流    int32_t ** flash_current = (int32_t **)data;    *flash_current = &(flash_ctrl->flash_max_current[0]);    goto flash_process_Exit;  }  case LED_FLASH_GET_MAX_DURATION: {
   			// 2. 获得双闪的最大电流    uint32_t* flash_duration = (uint32_t*)data;    *flash_duration = flash_ctrl->flash_max_duration[0];    goto flash_process_Exit;  }  case LED_FLASH_SET_CURRENT: {
   					// 3. 设置闪光灯的最大电流    /* Get currents for dual LED */    rc = flash_set_current(data, dual_led_setting);    goto flash_process_Exit;  }  case LED_FLASH_INIT:							// 4. 闪光灯初始化    rc = flash_init(flash_ctrl, data);    goto flash_process_Exit;  case LED_FLASH_SET_RER_CHROMATIX: {
   			// 5. 设置 红眼 chromatix 参数    rer_chromatix = (red_eye_reduction_type *)data;    /* Get (RER) data from chromatix */    rc = flash_rer_set_chromatix(rer, rer_chromatix);    goto flash_process_Exit;  }  case LED_FLASH_GET_RER_PARAMS: {
   				// 6. 获取 红眼 参数    *(int32_t *) data = rer->cfg->red_eye_reduction_led_flash_enable;    goto flash_process_Exit;  }  case LED_FLASH_SET_RER_PARAMS: {
   				// 7. 设置 红眼 参数    mode = (int32_t *)data;    rc = flash_rer_set_parm(rer, *mode);    goto flash_process_Exit;  }  case LED_FLASH_SET_FIRING_POWER:{
   				// 8. 设置电流    flashPower = *(uint8_t *)data;    goto flash_process_Exit;  }  case LED_FLASH_SET_RER_PROCESS: {
   				// 9. 配置红眼处理函数    led_module_params = (module_sensor_params_t *)data;    rc = flash_rer_sequence_process(rer, led_module_params);    goto flash_process_Exit;  }  case LED_FLASH_SET_OFF:						// 10. 关闭闪光灯    SHIGH("Turning off flash");    translate_sensor_reg_setting_array(flash_settings,      &(flash_ctrl->driver_lib_data->i2c_flash_info.flash_off_settings));    cfg.cfg_type = CFG_FLASH_OFF;    cfg.cfg.settings = flash_settings;    break;  case LED_FLASH_SET_TORCH:  case LED_FLASH_SET_PRE_FLASH: {
   				// 11. 开启 手电筒 或 开启预闪，下发参数 CFG_FLASH_LOW    SHIGH("Turning on torch/pre flash");    /* Pre flash mode */    translate_sensor_reg_setting_array(flash_settings,      		&(flash_ctrl->driver_lib_data->i2c_flash_info.flash_low_settings));    cfg.cfg_type = CFG_FLASH_LOW;    cfg.cfg.settings = flash_settings;    if (dual_led_setting->low_setting[0] == 0 && dual_led_setting->low_setting[1] == 0) {
         cfg.flash_current[0] = data ? *(int32_t *)data : default_current;      cfg.flash_current[1] = data ? *(int32_t *)data : default_current;    } else {
         cfg.flash_current[0] = dual_led_setting->low_setting[0];      cfg.flash_current[1] = dual_led_setting->low_setting[1];    }    break;  }  case LED_FLASH_SET_RER_PULSE_FLASH: {
   			// 12. 设置红眼 脉冲 电平    /* RER flash pulses */    translate_sensor_reg_setting_array(flash_settings,      &(flash_ctrl->driver_lib_data->i2c_flash_info.flash_high_settings));    cfg.cfg_type = CFG_FLASH_HIGH;    /* Use chromatix current if exist (set in RER_PROCESS)*/    cfg.flash_current[0] = data ? *(int32_t *)data : default_current;    cfg.flash_current[1] = data ? *(int32_t *)data : default_current;    cfg.cfg.settings = flash_settings;    temp = (dual_led_setting->high_setting[0] + dual_led_setting->high_setting[1]);    if (temp > 0) {
         /* Update with Dual LED current */      cfg.flash_current[0] = (cfg.flash_current[0] * dual_led_setting->high_setting[0]) / temp;      cfg.flash_current[1] = (cfg.flash_current[1] * dual_led_setting->high_setting[1]) / temp;    }    break;  }  case LED_FLASH_SET_MAIN_FLASH: {
   				// 13. 开启主闪    SHIGH("Turning on main flash");    /* Main flash mode */    translate_sensor_reg_setting_array(flash_settings,      		&(flash_ctrl->driver_lib_data->i2c_flash_info.flash_high_settings));    cfg.cfg_type = CFG_FLASH_HIGH;    cfg.cfg.settings = flash_settings;    if (dual_led_setting->high_setting[0] == 0 && dual_led_setting->high_setting[1] == 0) {
         cfg.flash_current[0] = data ? *(int32_t *)data : default_current;      cfg.flash_current[1] = data ? *(int32_t *)data : default_current;    } else {
         cfg.flash_current[0] = dual_led_setting->high_setting[0];      cfg.flash_current[1] = dual_led_setting->high_setting[1];    }    rc = flash_rer_wait_pupil_contract(rer, led_module_params);    break;  }  case LED_FLASH_GET_FRAME_SKIP_TIME_PARAMS:	// 14. 获取 帧数过滤 参数  {
       module_sensor_bundle_info_t* s_bundle = (module_sensor_bundle_info_t*)data;    rc = flash_get_frame_skip_timing_params(s_bundle,flash_ctrl);    goto flash_process_Exit;  }  }  rc = ioctl(flash_ctrl->fd, VIDIOC_MSM_FLASH_CFG, &cfg);flash_process_Exit:  free(flash_settings);  return rc;}

可以看出，操作闪光灯，都是操作 flash_process() 函数，最终都是通过 ioctl 来下发指令和参数的，还是比较好理解的。

接下来我们来看下 Kernel 中的代码。

四、[Kernel] flashlight 驱动

4.1 Kernel probe 初始化 msm_flash_platform_probe()

# msm-4.14/arch/arm64/boot/dts/qcom/sdm660-camera-sensor-mtp.dtsi&soc {
   	led_flash0: qcom,camera-flash@0 {
   		cell-index = <0>;		compatible = "qcom,camera-flash";		qcom,flash-source = <&pm660l_flash0 &pm660l_flash1>;		qcom,torch-source = <&pm660l_torch0 &pm660l_torch1>;		qcom,switch-source = <&pm660l_switch0>;		status = "ok";	};	led_flash1: qcom,camera-flash@1 {
   		cell-index = <1>;		compatible = "qcom,camera-flash";		qcom,flash-source = <&pm660l_flash2>;		qcom,torch-source = <&pm660l_torch2>;		qcom,switch-source = <&pm660l_switch1>;		status = "ok";	};

对应的c 代码位于： msm-4.14/drivers/media/platform/msm/camera_v2/sensor/flash/msm_flash.c

static const struct of_device_id msm_flash_dt_match[] = {
   	{
   .compatible = "qcom,camera-flash", .data = NULL},	{
   }};MODULE_DEVICE_TABLE(of, msm_flash_dt_match);static struct platform_driver msm_flash_platform_driver = {
   	.probe = msm_flash_platform_probe,	.driver = {
   		.name = "qcom,camera-flash",		.owner = THIS_MODULE,		.of_match_table = msm_flash_dt_match,	},};

主要工作流程：

解析dts 信息，包括 cell-index、qcom,cci-master、qcom,switch-source、qcom,flash-source、qcom,max-current、qcom,duration 等。

初始化V4L2 subdev，节点名为 /dev/v4l-subdevX

如果type = FLASH_DRIVER_PMIC，
会对每一个 touch_source 注册为 led 设备，创建一个sys 节点, qcom,led-name = "led:torch_0";

static int32_t msm_flash_platform_probe(struct platform_device *pdev){
   	struct msm_flash_ctrl_t *flash_ctrl = NULL;	struct msm_camera_cci_client *cci_client = NULL;	flash_ctrl = kzalloc(sizeof(struct msm_flash_ctrl_t), GFP_KERNEL);	memset(flash_ctrl, 0, sizeof(struct msm_flash_ctrl_t));	flash_ctrl->pdev = pdev;	// 1. 解析dts 信息，包括 cell-index、qcom,cci-master、	// qcom,switch-source、qcom,flash-source、qcom,max-current、qcom,duration	// qcom,torch-source、qcom,gpio-vana、qcom,gpio-vio、qcom,gpio-vaf、qcom,gpio-vdig、qcom,gpio-reset	// qcom,gpio-standby、qcom,gpio-af-pwdm、qcom,gpio-flash-en、qcom,gpio-flash-reset	rc = msm_flash_get_dt_data(pdev->dev.of_node, flash_ctrl);	// 2. 初始化 V4L2 subdev，节点名为 /dev/v4l-subdevX	flash_ctrl->flash_state = MSM_CAMERA_FLASH_RELEASE;	flash_ctrl->power_info.dev = &flash_ctrl->pdev->dev;	flash_ctrl->flash_device_type = MSM_CAMERA_PLATFORM_DEVICE;	flash_ctrl->flash_mutex = &msm_flash_mutex;	flash_ctrl->flash_i2c_client.i2c_func_tbl = &msm_sensor_cci_func_tbl;	flash_ctrl->flash_i2c_client.cci_client = kzalloc(		sizeof(struct msm_camera_cci_client), GFP_KERNEL);	cci_client = flash_ctrl->flash_i2c_client.cci_client;	cci_client->cci_subdev = msm_cci_get_subdev();	cci_client->cci_i2c_master = flash_ctrl->cci_i2c_master;	/* Initialize sub device */	v4l2_subdev_init(&flash_ctrl->msm_sd.sd, &msm_flash_subdev_ops);	v4l2_set_subdevdata(&flash_ctrl->msm_sd.sd, flash_ctrl);	flash_ctrl->msm_sd.sd.internal_ops = &msm_flash_internal_ops;	flash_ctrl->msm_sd.sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;	snprintf(flash_ctrl->msm_sd.sd.name, ARRAY_SIZE(flash_ctrl->msm_sd.sd.name),"msm_camera_flash");	media_entity_pads_init(&flash_ctrl->msm_sd.sd.entity, 0, NULL);	flash_ctrl->msm_sd.sd.entity.function = MSM_CAMERA_SUBDEV_FLASH;	flash_ctrl->msm_sd.close_seq = MSM_SD_CLOSE_2ND_CATEGORY | 0x1;	msm_sd_register(&flash_ctrl->msm_sd);	CDBG("%s:%d flash sd name = %s", __func__, __LINE__,		flash_ctrl->msm_sd.sd.entity.name);	msm_cam_copy_v4l2_subdev_fops(&msm_flash_v4l2_subdev_fops);#ifdef CONFIG_COMPAT	msm_flash_v4l2_subdev_fops.compat_ioctl32 =		msm_flash_subdev_fops_ioctl;#endif	flash_ctrl->msm_sd.sd.devnode->fops = &msm_flash_v4l2_subdev_fops;	// 3. 如果 type = FLASH_DRIVER_PMIC，	// 会对每一个 touch_source 注册为 led 设备，创建一个sys 节点, qcom,led-name = "led:torch_0";	if (flash_ctrl->flash_driver_type == FLASH_DRIVER_PMIC)		rc = msm_torch_create_classdev(pdev, flash_ctrl);		=========>			for (i = 0; i < fctrl->torch_num_sources; i++) {
   			if (fctrl->torch_trigger[i]) {
   				led_classdev_register(&pdev->dev, &msm_torch_led[i]);					----->						ret = led_add_brightness_hw_changed(led_cdev);						led_update_brightness(led_cdev);						led_init_core(led_cdev);						led_trigger_set_default(led_cdev);			}		<=========	CDBG("probe success\n");	return rc;}

好了，probe 流程，到这就完了，很常规的解析节点，注册V4L2，注册LED 设备，没啥好说的。

接下来，我们来看下上层操作闪光灯时，下发的一些指令是怎么跑的。

4.2 CFG_FLASH_INIT 初始化闪光灯

在闪光灯代码中，主要包括如下五种 ioctrl 指令：

enum msm_flash_cfg_type_t {
   	CFG_FLASH_INIT,		// 初始化	CFG_FLASH_RELEASE,	// 释放	CFG_FLASH_OFF,		// 关闭	CFG_FLASH_LOW,		// 手电筒 或 预闪	CFG_FLASH_HIGH,		// 主闪};

接下来，看下 init 做了什么事：

static int32_t msm_flash_config(struct msm_flash_ctrl_t *flash_ctrl, void *argp){
   	switch (flash_data->cfg_type) {
   	case CFG_FLASH_INIT:		rc = msm_flash_init_prepare(flash_ctrl, flash_data);		break;	}	rc = msm_flash_prepare(flash_ctrl);}

在 msm_flash_init_prepare() 中主要是，保存闪光灯电流参数，及保存上层下发的所有参数

static int32_t msm_flash_init_prepare(struct msm_flash_ctrl_t *flash_ctrl,	struct msm_flash_cfg_data_t *flash_data){
   	struct msm_flash_cfg_data_t flash_data_k;	struct msm_flash_init_info_t flash_init_info;	int32_t i = 0;	flash_data_k.cfg_type = flash_data->cfg_type;	for (i = 0; i < MAX_LED_TRIGGERS; i++) {
   		flash_data_k.flash_current[i] = flash_data->flash_current[i];		flash_data_k.flash_duration[i] = flash_data->flash_duration[i];	}	flash_data_k.cfg.flash_init_info = &flash_init_info;	if (copy_from_user(&flash_init_info,(void __user *)(flash_data->cfg.flash_init_info),		sizeof(struct msm_flash_init_info_t))) {
   		pr_err("%s copy_from_user failed %d\n",__func__, __LINE__);		return -EFAULT;	}	return msm_flash_init(flash_ctrl, &flash_data_k);}

接着调用 msm_flash_init()，

在函数中，通过 camera_flash_init() 函数来下发参数，初始化 flash_state = MSM_CAMERA_FLASH_INIT。

# msm-4.14/drivers/media/platform/msm/camera_v2/sensor/flash/msm_flash.cstatic int32_t msm_flash_init(struct msm_flash_ctrl_t *flash_ctrl,struct msm_flash_cfg_data_t *flash_data){
   	uint32_t i = 0;	int32_t rc = -EFAULT;	enum msm_flash_driver_type flash_driver_type = FLASH_DRIVER_DEFAULT;	CDBG("Enter");	if (flash_data->cfg.flash_init_info->flash_driver_type == FLASH_DRIVER_DEFAULT) {
   		flash_driver_type = flash_ctrl->flash_driver_type;		for (i = 0; i < MAX_LED_TRIGGERS; i++) {
   			flash_data->flash_current[i] = flash_ctrl->flash_max_current[i];			flash_data->flash_duration[i] = flash_ctrl->flash_max_duration[i];		}	} else if (flash_data->cfg.flash_init_info->flash_driver_type == flash_ctrl->flash_driver_type) {
   		flash_driver_type = flash_ctrl->flash_driver_type;		for (i = 0; i < MAX_LED_TRIGGERS; i++) {
   			flash_ctrl->flash_max_current[i] = flash_data->flash_current[i];			flash_ctrl->flash_max_duration[i] = flash_data->flash_duration[i];		}	}	for (i = 0; i < ARRAY_SIZE(flash_table); i++) {
   		if (flash_driver_type == flash_table[i]->flash_driver_type) {
   			flash_ctrl->func_tbl = &flash_table[i]->func_tbl;			rc = 0;		}	}	if (flash_ctrl->func_tbl->camera_flash_init) {
   		rc = flash_ctrl->func_tbl->camera_flash_init(flash_ctrl, flash_data);	}	flash_ctrl->flash_state = MSM_CAMERA_FLASH_INIT;	CDBG("Exit");	return 0;}

camera_flash_init定义如下：

可以看出，当使和pmic 时，是不需要进行 camera_flash_init() 的，函数为空。

如果走的是 gpio ，就会开始关闭所有的gpio，详细可以自行分析 msm_flash_gpio_init()。

如果 i2c ，则会初始化上电，然后通过 i2c 定义闪光灯相关的配置。

#msm-4.14/drivers/media/platform/msm/camera_v2/sensor/flash/msm_flash.c static struct msm_flash_table msm_pmic_flash_table = {
   	.flash_driver_type = FLASH_DRIVER_PMIC,	.func_tbl = {
   		.camera_flash_init = NULL,		.camera_flash_release = msm_flash_release,		.camera_flash_off = msm_flash_off,		.camera_flash_low = msm_flash_low,		.camera_flash_high = msm_flash_high,		.camera_flash_query_current = msm_flash_query_current,	},};static struct msm_flash_table msm_gpio_flash_table = {
   	.flash_driver_type = FLASH_DRIVER_GPIO,	.func_tbl = {
   		.camera_flash_init = msm_flash_gpio_init,		.camera_flash_release = msm_flash_release,		.camera_flash_off = msm_flash_off,		.camera_flash_low = msm_flash_low,		.camera_flash_high = msm_flash_high,		.camera_flash_query_current = NULL,	},};static struct msm_flash_table msm_i2c_flash_table = {
   	.flash_driver_type = FLASH_DRIVER_I2C,	.func_tbl = {
   		.camera_flash_init = msm_flash_i2c_init,		.camera_flash_release = msm_flash_i2c_release,		.camera_flash_off = msm_flash_i2c_write_setting_array,		.camera_flash_low = msm_flash_i2c_write_setting_array,		.camera_flash_high = msm_flash_i2c_write_setting_array,		.camera_flash_query_current = NULL,	},};

最终，还会调用 rc = msm_flash_prepare(flash_ctrl);

switch_trigger 对应的就是 dts 中的 qcom,switch-source = <&pm660l_switch0>;

其内容如下：

pm660l_switch0: qcom,led_switch_0 {
   				label = "switch";				qcom,led-name = "led:switch_0";				qcom,led-mask = <3>;				qcom,default-led-trigger = "switch0_trigger";			};

我们来看下 msm_flash_prepare 的代码，在代码中，就是通过 switch 进行上电。

static int32_t msm_flash_prepare(struct msm_flash_ctrl_t *flash_ctrl){
   	if (flash_ctrl->switch_trigger == NULL) {
   		pr_err("%s:%d Invalid argument\n",__func__, __LINE__);		return -EINVAL;	}	// 1. 上电	if (flash_ctrl->flash_state == MSM_CAMERA_FLASH_INIT &&		flash_ctrl->is_regulator_enabled == 0) {
   		ret = qpnp_flash_led_prepare(flash_ctrl->switch_trigger, ENABLE_REGULATOR, NULL);		flash_ctrl->is_regulator_enabled = 1;	} else if (flash_ctrl->flash_state == MSM_CAMERA_FLASH_RELEASE &&		flash_ctrl->is_regulator_enabled) {
   		ret = qpnp_flash_led_prepare(flash_ctrl->switch_trigger,DISABLE_REGULATOR, NULL);		flash_ctrl->is_regulator_enabled = 0;	}	CDBG("%s:%d:Exit\n", __func__, __LINE__);	return ret;}

看下 qpnp_flash_led_prepare() 代码：

有关 led 子系统的代码，可以分析下 msm-4.14/drivers/leds/leds-qpnp-flash-v2.c，有机会我们后面分析，

今天主要分析闪光灯的流程，点到为止，不然篇幅会太长了。

int qpnp_flash_led_prepare(struct led_trigger *trig, int options,int *max_current){
   	// 通过 led:switch_0 名字，找到 led dev设备	led_cdev = trigger_to_lcdev(trig);	// 上电	rc = qpnp_flash_led_regulator_control(led_cdev, options, max_current);	return rc;}

4.3 CFG_FLASH_LOW 开启手电筒或开启预闪

static int32_t msm_flash_config(struct msm_flash_ctrl_t *flash_ctrl, void *argp){
   case CFG_FLASH_LOW:		if ((flash_ctrl->flash_state == MSM_CAMERA_FLASH_OFF) || (flash_ctrl->flash_state == MSM_CAMERA_FLASH_INIT)) {
   			rc = flash_ctrl->func_tbl->camera_flash_low(flash_ctrl, flash_data);		}		break;}

接下来，我们进入 msm_flash_low() 函数看下，

通过 led_trigger_event() 来点亮。

static int32_t msm_flash_low(struct msm_flash_ctrl_t *flash_ctrl,struct msm_flash_cfg_data_t *flash_data){
   	CDBG("Enter\n");	/* Turn off flash triggers */	for (i = 0; i < flash_ctrl->flash_num_sources; i++)		if (flash_ctrl->flash_trigger[i])			led_trigger_event(flash_ctrl->flash_trigger[i], 0);	/* Turn on flash triggers */	for (i = 0; i < flash_ctrl->torch_num_sources; i++) {
   		if (flash_ctrl->torch_trigger[i]) {
   			max_current = flash_ctrl->torch_max_current[i];			if (flash_data->flash_current[i] >= 0 && flash_data->flash_current[i] < max_current) {
   				curr = flash_data->flash_current[i];			} else {
   				curr = flash_ctrl->torch_op_current[i];				pr_debug("LED current clamped to %d\n", curr);			}			CDBG("low_flash_current[%d] = %d", i, curr);			led_trigger_event(flash_ctrl->torch_trigger[i], curr);		}	}	if (flash_ctrl->switch_trigger)		led_trigger_event(flash_ctrl->switch_trigger, 1);	CDBG("Exit\n");	return 0;}

4.4 CFG_FLASH_OFF 关闭闪光灯

case CFG_FLASH_OFF:		rc = flash_ctrl->func_tbl->camera_flash_off(flash_ctrl, flash_data);

很好理解，通过 led_trigger_event() 来触发关闭

static int32_t msm_flash_off(struct msm_flash_ctrl_t *flash_ctrl,struct msm_flash_cfg_data_t *flash_data){
   	int32_t i = 0;	CDBG("Enter\n");	for (i = 0; i < flash_ctrl->flash_num_sources; i++)		if (flash_ctrl->flash_trigger[i])			led_trigger_event(flash_ctrl->flash_trigger[i], 0);	for (i = 0; i < flash_ctrl->torch_num_sources; i++)		if (flash_ctrl->torch_trigger[i])			led_trigger_event(flash_ctrl->torch_trigger[i], 0);				if (flash_ctrl->switch_trigger)		led_trigger_event(flash_ctrl->switch_trigger, 0);	CDBG("Exit\n");	return 0;}

4.5 CFG_FLASH_HIGH 开启主闪

case CFG_FLASH_HIGH:		rc = flash_ctrl->func_tbl->camera_flash_high(flash_ctrl, flash_data);

static int32_t msm_flash_high( struct msm_flash_ctrl_t *flash_ctrl, struct msm_flash_cfg_data_t *flash_data){
   	/* Turn off torch triggers */	for (i = 0; i < flash_ctrl->torch_num_sources; i++)		if (flash_ctrl->torch_trigger[i])			led_trigger_event(flash_ctrl->torch_trigger[i], 0);	/* Turn on flash triggers */	for (i = 0; i < flash_ctrl->flash_num_sources; i++) {
   		if (flash_ctrl->flash_trigger[i]) {
   			max_current = flash_ctrl->flash_max_current[i];			if (flash_data->flash_current[i] >= 0 && flash_data->flash_current[i] < max_current) {
   				curr = flash_data->flash_current[i];			} else {
   				curr = flash_ctrl->flash_op_current[i];				pr_debug("LED flash_current[%d] clamped %d\n", i, curr);			}			CDBG("high_flash_current[%d] = %d", i, curr);			led_trigger_event(flash_ctrl->flash_trigger[i], curr);		}	}	if (flash_ctrl->switch_trigger)		led_trigger_event(flash_ctrl->switch_trigger, 1);	return 0;}

好啦，闪光灯代码，就先看到这里，前面逻辑还是比较好理解的，

后面到了kernel 层，主要就是led 子系统的工作了，由它来实现点亮和关闭灯。

后面有时间，我们再来单独分析下，LED 子系统。

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