一.主要文件

kernel-4.19/drivers/misc/mediatek/imgsensor/src/common/v1/imgsensor_hw.c

1.1 主要函数

imgsensor_hw.c共计就四个函数：

imgsensor_hw_init
imgsensor_hw_power
imgsensor_hw_power_sequence
imgsensor_hw_release_all

看名字就可以知道函数实现的功能。

1.2 上电相关的结构体

pdev[IMGSENSOR_HW_ID_MAX_NUM]这个结构体指针数组用来保存控制上电方式的设备（gpio/regulator）和控制时钟相关的设备，这个结构主要保存了一些函数指针，用来调用设备的init、set等方法。

sensor_pwr[IMGSENSOR_SENSOR_IDX_MAX_NUM]用来保存上电方式和上电顺序等信息，这是一个数组，可以保存多个sensor的信息。
ppwr_info保存pin的信息，比如状态，延迟等，指针类型，通过加减操作移动到下一个位置，和数组差不多，能保存多个pin。
id[]数组用来保存每个pin的上电方式。

二.上电流程

2.1 imgsensor_hw_init()

在probe()函数中已经初始化上电所需要的信息，用到了imgsensor_hw_init()函数：

enum IMGSENSOR_RETURN imgsensor_hw_init(struct IMGSENSOR_HW *phw) {struct IMGSENSOR_HW_SENSOR_POWER *psensor_pwr;struct IMGSENSOR_HW_CFG *pcust_pwr_cfg;struct IMGSENSOR_HW_CUSTOM_POWER_INFO *ppwr_info;int i, j;char str_prop_name[LENGTH_FOR_SNPRINTF];//LENGTH_FOR_SNPRINTF 256struct device_node *of_node= of_find_compatible_node(NULL, NULL, "mediatek,camera_hw");/* 初始化pdev数组，绑定上电和时钟控制设备 */for (i = 0; i < IMGSENSOR_HW_ID_MAX_NUM; i++) {//IMGSENSOR_HW_ID_MAX_NUM 3if (hw_open[i] != NULL)(hw_open[i])(&phw->pdev[i]);if (phw->pdev[i]->init != NULL)(phw->pdev[i]->init)(phw->pdev[i]->pinstance);}for (i = 0; i < IMGSENSOR_SENSOR_IDX_MAX_NUM; i++) {//IMGSENSOR_SENSOR_IDX_MAX_NUM 3psensor_pwr = &phw->sensor_pwr[i];pcust_pwr_cfg = imgsensor_custom_config;while (pcust_pwr_cfg->sensor_idx != i &&pcust_pwr_cfg->sensor_idx != IMGSENSOR_SENSOR_IDX_NONE)//IMGSENSOR_SENSOR_IDX_NONE 6pcust_pwr_cfg++;if (pcust_pwr_cfg->sensor_idx == IMGSENSOR_SENSOR_IDX_NONE)continue;ppwr_info = pcust_pwr_cfg->pwr_info;while (ppwr_info->pin != IMGSENSOR_HW_PIN_NONE) {//IMGSENSOR_HW_PIN_NONE 0for (j = 0; j < IMGSENSOR_HW_ID_MAX_NUM; j++)//IMGSENSOR_HW_ID_MAX_NUM 3if (ppwr_info->id == phw->pdev[j]->id)break;psensor_pwr->id[ppwr_info->pin] = j;ppwr_info++;}}/* 读设备树，? */for (i = 0; i < IMGSENSOR_SENSOR_IDX_MAX_NUM; i++) {memset(str_prop_name, 0, sizeof(str_prop_name));snprintf(str_prop_name,sizeof(str_prop_name),"cam%d_%s",i,"enable_sensor");if (of_property_read_string(of_node,str_prop_name,&phw->enable_sensor_by_index[i]) < 0) {pr_info("Property cust-sensor not defined\n");phw->enable_sensor_by_index[i] = NULL;}}return IMGSENSOR_RETURN_SUCCESS;
}

分析这个函数，依次做了下面这些事：

1.第一个for循环初始化了pdev数组，绑定上电和时钟控制设备。程序中hw_open数组定义如下：

enum IMGSENSOR_RETURN
(*hw_open[IMGSENSOR_HW_ID_MAX_NUM])(struct IMGSENSOR_HW_DEVICE **) = {imgsensor_hw_regulator_open,imgsensor_hw_gpio_open,imgsensor_hw_mclk_open
};

也就是保存了三个函数指针，调用这三个函数就可以初始化pdev数组，例如imgsensor_hw_regulator_open()函数定义如下：

static struct IMGSENSOR_HW_DEVICE device = {.pinstance = (void *) &reg_instance,.init      = regulator_init,.set       = regulator_set,.release   = regulator_release,.id        = IMGSENSOR_HW_ID_REGULATOR
};enum IMGSENSOR_RETURN imgsensor_hw_regulator_open(struct IMGSENSOR_HW_DEVICE **pdevice) {*pdevice = &device;return IMGSENSOR_RETURN_SUCCESS;
}

可以看到就是绑定了一些操作函数，通过对某个pin脚调用set函数就可以完成对它的上电操作。

2.第二个for循环是为sensor设置上电顺序，前面提到的enum IMGSENSOR_HW_ID id[IMGSENSOR_HW_PIN_MAX_NUM]数组就保存了当前sensor引脚的上电方式。

分析代码，这里有一个数组imgsensor_custom_config[ ]，它的作用是配置sensor每个引脚的上电方式，在imgsensor_cfg_table.c中：

struct IMGSENSOR_HW_CFG imgsensor_custom_config[] = {{IMGSENSOR_SENSOR_IDX_MAIN,//sensor_idIMGSENSOR_I2C_DEV_0,//sensor_i2c dev{           //上电方式                                      pin脚{IMGSENSOR_HW_ID_MCLK, IMGSENSOR_HW_PIN_MCLK},{IMGSENSOR_HW_ID_REGULATOR, IMGSENSOR_HW_PIN_AVDD},{IMGSENSOR_HW_ID_REGULATOR, IMGSENSOR_HW_PIN_DOVDD},{IMGSENSOR_HW_ID_GPIO,      IMGSENSOR_HW_PIN_DVDD},{IMGSENSOR_HW_ID_GPIO, IMGSENSOR_HW_PIN_PDN},{IMGSENSOR_HW_ID_GPIO, IMGSENSOR_HW_PIN_RST},{IMGSENSOR_HW_ID_NONE, IMGSENSOR_HW_PIN_NONE},},},/* 省略部分代码 */
};

首先通过第一个while循环将sensorid和当前要操作的sensor对应起来，然后通过第二个while循环来拿到imgsensor_custom_config[]中的上电方式，将这个上电方式与一开始初始化的pdev中的设备对应起来，得到pdev对应设备的索引 j ，最后通过赋值操作把上电方式和引脚保存到enum IMGSENSOR_HW_ID id[IMGSENSOR_HW_PIN_MAX_NUM]这个数组中，匹配结果如下：

3.最后一个for循环读设备树，读到的是sensor的名字，在后面imgsensor_hw_power()函数会进行字符串匹配验证，这里的作用以后在探究。

2.2imgsensor_hw_power()

就是用来上电的函数：

enum IMGSENSOR_RETURN imgsensor_hw_power(struct IMGSENSOR_HW *phw,struct IMGSENSOR_SENSOR *psensor,char *curr_sensor_name,enum IMGSENSOR_HW_POWER_STATUS pwr_status) {enum IMGSENSOR_SENSOR_IDX sensor_idx = psensor->inst.sensor_idx;char str_index[LENGTH_FOR_SNPRINTF];int ret = 0;pr_info("sensor_idx %d, power %d curr_sensor_name %s, enable list %s\n",sensor_idx,pwr_status,curr_sensor_name,phw->enable_sensor_by_index[(uint32_t) sensor_idx] == NULL? "NULL": phw->enable_sensor_by_index[(uint32_t) sensor_idx]);if (phw->enable_sensor_by_index[(uint32_t) sensor_idx] &&!strstr(phw->enable_sensor_by_index[(uint32_t) sensor_idx], curr_sensor_name))return IMGSENSOR_RETURN_ERROR;ret = snprintf(str_index, sizeof(str_index), "%d", sensor_idx);if (ret == 0) {pr_info("Error! snprintf allocate 0");ret = IMGSENSOR_RETURN_ERROR;return ret;}imgsensor_hw_power_sequence(phw,sensor_idx,pwr_status,platform_power_sequence,str_index);imgsensor_hw_power_sequence(phw,sensor_idx,pwr_status,sensor_power_sequence,curr_sensor_name);return IMGSENSOR_RETURN_SUCCESS;
}

这个函数主要就调用了imgsensor_hw_power_sequence(),这里调用了两次，主要是第四个参数不同，platform_power_sequence[]配置的是平台上电顺序，sensor_power_sequence[]配置的是sensor上电顺序，它们都在imgsensor_cfg_table.c中。在某个sensor上电的时候会匹配上其中一种进行上电。

2.3 imgsensor_hw_power_sequence()

static enum IMGSENSOR_RETURN imgsensor_hw_power_sequence(struct IMGSENSOR_HW *phw,enum IMGSENSOR_SENSOR_IDX sensor_idx,enum IMGSENSOR_HW_POWER_STATUS pwr_status,struct IMGSENSOR_HW_POWER_SEQ *ppower_sequence,char *pcurr_idx) {struct IMGSENSOR_HW_SENSOR_POWER *psensor_pwr =&phw->sensor_pwr[sensor_idx];struct IMGSENSOR_HW_POWER_SEQ *ppwr_seq = ppower_sequence;struct IMGSENSOR_HW_POWER_INFO *ppwr_info;struct IMGSENSOR_HW_DEVICE *pdev;int pin_cnt = 0;/* 匹配上电的方式，是platform还是sensor */while (ppwr_seq < ppower_sequence + IMGSENSOR_HW_SENSOR_MAX_NUM &&ppwr_seq->name != NULL) {if (!strcmp(ppwr_seq->name, PLATFORM_POWER_SEQ_NAME)) {if (sensor_idx == ppwr_seq->_idx)break;} else {if (!strcmp(ppwr_seq->name, pcurr_idx))break;}ppwr_seq++;}if (ppwr_seq->name == NULL) {return IMGSENSOR_RETURN_ERROR;}ppwr_info = ppwr_seq->pwr_info;/* 依次为pin上电 */while (ppwr_info->pin != IMGSENSOR_HW_PIN_NONE &&ppwr_info < ppwr_seq->pwr_info + IMGSENSOR_HW_POWER_INFO_MAX) {if (pwr_status == IMGSENSOR_HW_POWER_STATUS_ON &&ppwr_info->pin != IMGSENSOR_HW_PIN_UNDEF) {/* 匹配上电的设备，是gpio还是regulator等等 */pdev = phw->pdev[psensor_pwr->id[ppwr_info->pin]];if (pdev->set != NULL)/* 调用设备的set()进行上电 */pdev->set(pdev->pinstance,sensor_idx,ppwr_info->pin,ppwr_info->pin_state_on);mdelay(ppwr_info->pin_on_delay);}ppwr_info++;pin_cnt++;}/* 下电方式类似 */if (pwr_status == IMGSENSOR_HW_POWER_STATUS_OFF) {while (pin_cnt) {ppwr_info--;pin_cnt--;if (ppwr_info->pin != IMGSENSOR_HW_PIN_UNDEF) {pdev =phw->pdev[psensor_pwr->id[ppwr_info->pin]];mdelay(ppwr_info->pin_on_delay);if (pdev->set != NULL)pdev->set(pdev->pinstance,sensor_idx,ppwr_info->pin,ppwr_info->pin_state_off);}}}/* wait for power stable */if (pwr_status == IMGSENSOR_HW_POWER_STATUS_ON)mdelay(5);return IMGSENSOR_RETURN_SUCCESS;
}

这里匹配上电的设备就用到了上面那个id[]数组，通过pin的序号拿到其上电所需要的对应的设备，然后set即可完成上电。

暂时写到这里，别的后面在写，希望大家提出意见，共同学习。

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