一、概序：
前文已經介紹了camera驅動部分的内容Camera４ MTK camera驅動結構介紹，這裡在回顧下之前的架構圖，
這篇主要介紹紅框部分的内容：
imgsensor起到承上啟下的作用，在系統起來時會建立整個camera驅動運作的環境，其中主要的
檔案和函數如下框圖所示，先裝置挂載時會調用注冊platform裝置platform_driver_register，在比對成
功後會調用probe函數進行初始相關的裝置：
其中camera的三路電壓的上電方式可以通過GPIO來控制，也可以通過PMIC(REGULATOR)的方式來
進行控制，在imgsensor_hw中通過不同的pdev資訊，調用不同的set函數。涉及的檔案路徑：
kernel-4.9/drivers/misc/mediatek/imgsensor/src/common/v1/imgsensor.c
kernel-4.9/drivers/misc/mediatek/imgsensor/src/common/v1/imgsensor_hw.c
kernel-4.9/drivers/misc/mediatek/imgsensor/src/mt6765/camera_hw/regulator/regulator.c
kernel-4.9/drivers/misc/mediatek/imgsensor/src/mt6765/camera_hw/gpio/gpio.c
二、上電相關的結構體之間的聯系：
（1）IMGSENSOR_HW結構體：
IMGSENSOR_HW結構體包含了pdev(gpio/regulator)的裝置結構體和上電時序相關的結構體：
（2）上電時序控制相關：
上電方式控制：GPIO?REGULATOR?
上電時序控制結構體：
三、系統初始化：
１、裝置加載：
imgsensor和其他的驅動子產品相同，也是通過module_init來初始化子產品，在init中注冊platform總線驅動，
進而需要對應的platform_driver結構體資訊：
static const struct of_device_id gimgsensor_of_device_id[] = {
{ .compatible = "mediatek,camera_hw", },
{}
};
static struct platform_driver gimgsensor_platform_driver = {
.probe = imgsensor_probe,
.remove = imgsensor_remove,
.suspend = imgsensor_suspend,
.resume = imgsensor_resume,
.driver = {
.name = "image_sensor",
.owner = THIS_MODULE,
#ifdef CONFIG_OF
.of_match_table = gimgsensor_of_device_id,
#endif
}
};
當gimgsensor_of_device_id的資訊在dts中match上以後回執行到對應的probe函數，probe中主要注冊
了sensordrv的字元裝置和初始化imgsensor的硬體資訊(時鐘及上電)：
static int imgsensor_probe(struct platform_device *pdev)
{
/* Register char driver */
imgsensor_driver_register();
gpimgsensor_hw_platform_device = pdev;
imgsensor_clk_init(&pgimgsensor->clk);
imgsensor_hw_init(&pgimgsensor->hw);
imgsensor_i2c_create();
imgsensor_proc_init();
atomic_set(&pgimgsensor->imgsensor_open_cnt, 0);
return 0;
}
2、imgsensor_driver_register建立字元裝置：
//字元裝置的file_operation結構體
static const struct file_operations gimgsensor_file_operations = {
.owner = THIS_MODULE,
.open = imgsensor_open,
.release = imgsensor_release,
.unlocked_ioctl = imgsensor_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = imgsensor_compat_ioctl
#endif
};
static inline int imgsensor_driver_register(void){
//配置設定一個裝置号和nanme
alloc_chrdev_region(&dev_no, 0, 1, IMGSENSOR_DEV_NAME)
/* Allocate driver */
gpimgsensor_cdev = cdev_alloc();
/* Attatch file operation. */
cdev_init(gpimgsensor_cdev, &gimgsensor_file_operations);
/* Add to system */
cdev_add(gpimgsensor_cdev, dev_no, 1);
gpimgsensor_class = class_create(THIS_MODULE, "sensordrv");
device_create(gpimgsensor_class, NULL, dev_no, NULL, IMGSENSOR_DEV_NAME);
}
3、imgsensor_clk_init 時鐘初始化：
enum IMGSENSOR_RETURN imgsensor_clk_init(struct IMGSENSOR_CLK *pclk)
{
int i;
struct platform_device *pplatform_dev = gpimgsensor_hw_platform_device;
/* get all possible using clocks */
for (i = 0; i < IMGSENSOR_CCF_MAX_NUM; i++)
pclk->imgsensor_ccf[i] =
devm_clk_get(&pplatform_dev->dev, gimgsensor_mclk_name[i]);
return IMGSENSOR_RETURN_SUCCESS;
}
4、imgsensor_hw_init電壓初始化：
（１）依次調用GPIO/REGULATOR/MCLK的init接口；
（2）解析出imgsensor_custom_config，擷取到對應sensor的對應管腳(DVDD/AVDD...)的上電方式（GPIO/REGULATOR）;
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];
struct device_node *of_node
= of_find_compatible_node(NULL, NULL, "mediatek,camera_hw");
//依次調用GPIO/REGULATOR/MCLK的init接口；
for (i = 0; i < IMGSENSOR_HW_ID_MAX_NUM; i++) {
if (hw_open[i] != NULL)
(hw_open[i])(&phw->pdev[i]);
if (phw->pdev[i]->init != NULL)
(phw->pdev[i]->init)(phw->pdev[i]->pinstance);
}
//解析出imgsensor_custom_config
for (i = 0; i < IMGSENSOR_SENSOR_IDX_MAX_NUM; i++) {
psensor_pwr = &phw->sensor_pwr[i];
pcust_pwr_cfg = imgsensor_custom_config;//上電時序
while (pcust_pwr_cfg->sensor_idx != i)
pcust_pwr_cfg++;
//退出循環
if (pcust_pwr_cfg->sensor_idx == IMGSENSOR_SENSOR_IDX_NONE)
continue;
//ppwr_info對應{IMGSENSOR_HW_ID_GPIO, IMGSENSOR_HW_PIN_AVDD}
ppwr_info = pcust_pwr_cfg->pwr_info;
while (ppwr_info->pin != IMGSENSOR_HW_PIN_NONE) {
//查詢imgsensor_custom_config中ID_PIN 是否在GPIO/REGULATOR/Mclk中?
for (j = 0; j < IMGSENSOR_HW_ID_MAX_NUM; j++){
if (ppwr_info->id == phw->pdev[j]->id)
break;
}
//将對應sensor的對應PIN(DVDD/AVDD...)設定為系統的ID_PIN(GPIO/REGULATOR/MCKL)
psensor_pwr->id[ppwr_info->pin] = j;
ppwr_info++;
}
}
//判斷dts中是否設定對應的index為對應的name,如:cam3_enable_sensor = "gc2375hmain3_mipi_raw";
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;
}
5、imgsensor_i2c_create I2C裝置初始化：
enum IMGSENSOR_RETURN imgsensor_i2c_create(void)
{
int i;
for (i = 0; i < IMGSENSOR_I2C_DEV_MAX_NUM; i++)
i2c_add_driver(&gi2c_driver[i]);
return IMGSENSOR_RETURN_SUCCESS;
}
6、具體類型的上電介紹（以pmic控制的regulator方式為例）
前面imgsensor_hw_init中有去調用imgsensor_hw_regulator_open和regulator_init：
（1）傳入對應的裝置的device結構體：
static struct IMGSENSOR_HW_DEVICE device = {
.pinstance = (void *)®_instance,
.init = regulator_init,//開機初始化時調用
.set = regulator_set,//在上電設定電壓時會調用
.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;
}
（2）調用對應的init進行初始化：
因為MTK 平台的PMIC上電是通過統一的REGULATOR進行統一管理的，每一種上電方式需要申請對應type
的regulator控制的結構體，才可以來進行設定：
enum REGULATOR_TYPE {
REGULATOR_TYPE_VCAMA,
REGULATOR_TYPE_VCAMD,
REGULATOR_TYPE_VCAMIO,
REGULATOR_TYPE_MAX_NUM
};
static enum IMGSENSOR_RETURN regulator_init(void *pinstance)
{
struct REGULATOR *preg = (struct REGULATOR *)pinstance;
struct device *pdevice;
struct device_node *pof_node;
int j, i;
char str_regulator_name[LENGTH_FOR_SNPRINTF];
pdevice = gimgsensor_device;
for (j = IMGSENSOR_SENSOR_IDX_MIN_NUM;j < IMGSENSOR_SENSOR_IDX_MAX_NUM;j++) {
for (i = 0; i < REGULATOR_TYPE_MAX_NUM; i++) {
snprintf(str_regulator_name,
sizeof(str_regulator_name),
"cam%d_%s", j,
regulator_control[i].pregulator_type);
preg->pregulator[j][i] =
regulator_get(pdevice, str_regulator_name);
if (preg->pregulator[j][i] == NULL)
pr_err("regulator[%d][%d] %s fail!\n",
j, i, str_regulator_name);
atomic_set(&preg->enable_cnt[j][i], 0);
}
}
pdevice->of_node = pof_node;
imgsensor_oc_init();
return IMGSENSOR_RETURN_SUCCESS;
}
到這裡imgsensor部分的内容還有對上(hal層)承接的ioctl相關的内容沒有介紹，這部分的内容會在後續的
整個系統調用流程中進行梳理。
作者：frank_zyp
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