MTK6580（Android6.0)-camera 驱动分析

一、MTK6580 平台 Camera 驱动整体框架

mtk平台三大件调试中，camera的调试难度最大，问题也就最多，为此特地分析了一下整个camera驱动部分

实现过程，以下为camera驱动框架序列图：

      

从图中可以看出，整个框架分为三个部分hal部分逻辑调用，kernel层的通用驱动sensorlist.c 和具体IC的驱动

xxxx_mipi_raw.c，kernel起来后不会直接去访问硬件sensor,而是会注册相关的驱动，之后Android系统起来后

会启动相关的服务如：camera_service，在camera服务中会直接去访问hal,kernel驱动，进而操作camera。

为此本文也穿插了部分hal层的调用,至于camera_service后面章节会继续补充。

二、 Camera 驱动的具体实现

========================HAL 层部分初始调用========================
文件：vendor/mediatek/proprietary/hardware/mtkcam/common/module_hal/devicemgr/CamDeviceManagerBase.cpp

int32_tCamDeviceManagerBase::getNumberOfDevices(){...        mi4DeviceNum = enumDeviceLocked();    ...}

文件：vendor/mediatek/proprietary/hardware/mtkcam/legacy/platform/mt6580/devicemgr/CamDeviceManagerImp.cpp

int32_tCamDeviceManagerImp::enumDeviceLocked(){...//------------------------------------------------------------------------------#if '1'==MTKCAM_HAVE_SENSOR_HAL    //    IHalSensorList*const pHalSensorList = IHalSensorList::get();    size_t const sensorNum = pHalSensorList->searchSensors();#endif...    return  i4DeviceNum;}

文件：vendor/mediatek/proprietary/hardware/mtkcam/legacy/platform/mt6580/hal/sensor/HalSensorList.cpp

MUINTHalSensorList::searchSensors(){    Mutex::Autolock _l(mEnumSensorMutex);    //    MY_LOGD("searchSensors");    return  enumerateSensor_Locked();}

文件：vendor/mediatek/proprietary/hardware/mtkcam/legacy/platform/mt6580/hal/sensor/HalSensorList.enumList.cpp

MUINTHalSensorList::enumerateSensor_Locked(){....    MUINT halSensorDev = SENSOR_DEV_NONE;    NSFeature::SensorInfoBase* pSensorInfo ;    SensorDrv *const pSensorDrv = SensorDrv::get();    SeninfDrv *const pSeninfDrv = SeninfDrv::createInstance();    int const iSensorsList = pSensorDrv->impSearchSensor(NULL);....}

文件：vendor/mediatek/proprietary/hardware/mtkcam/legacy/platform/mt6580/hal/sensor/imgsensor_drv.cpp

MINT32ImgSensorDrv::impSearchSensor(pfExIdChk pExIdChkCbf){....    GetSensorInitFuncList(&m_pstSensorInitFunc);    LOG_MSG("SENSOR search start \n");    sprintf(cBuf,"/dev/%s",CAMERA_HW_DEVNAME);    m_fdSensor = ::open(cBuf, O_RDWR);......        for (i = 0; i < MAX_NUM_OF_SUPPORT_SENSOR; i++) {....            err = ioctl(m_fdSensor, KDIMGSENSORIOC_X_SET_DRIVER,&id[KDIMGSENSOR_INVOKE_DRIVER_0] );...            err = ioctl(m_fdSensor, KDIMGSENSORIOC_T_CHECK_IS_ALIVE);......}

GetSensorInitFuncList的实现
文件：vendor/mediatek/proprietary/custom/mt6580/hal/imgsensor_src/sensorlist.cpp

UINT32 GetSensorInitFuncList(MSDK_SENSOR_INIT_FUNCTION_STRUCT **ppSensorList){    if (NULL == ppSensorList) {        ALOGE("ERROR: NULL pSensorList\n");        return MHAL_UNKNOWN_ERROR;    }    *ppSensorList = &SensorList[0];    return MHAL_NO_ERROR;} 

Sensor 列表的定义如下：

MSDK_SENSOR_INIT_FUNCTION_STRUCT SensorList[] ={//xc add camera start#if defined(GC2365MIPI_RAW)    RAW_INFO(GC2365MIPI_SENSOR_ID, SENSOR_DRVNAME_GC2365MIPI_RAW, NULL),#endif#if defined(GC2355_MIPI_RAW_BAIKANG_M8112)    RAW_INFO(GC2355_SENSOR_ID, SENSOR_DRVNAME_GC2355_MIPI_RAW,NULL),#endif....}

获取sensor列表后，紧接着通过：
err = ioctl(m_fdSensor, KDIMGSENSORIOC_X_SET_DRIVER,&id[KDIMGSENSOR_INVOKE_DRIVER_0] );
err = ioctl(m_fdSensor, KDIMGSENSORIOC_T_CHECK_IS_ALIVE);
访问kernel层的数据
====================== Kernel 层驱动的实现 ========================
1. 针对前后摄注册platform 设备和驱动
文件：kernel-3.18/drivers/misc/mediatek/imgsensor/src/mt6580/kd_sensorlist.c

static int __init CAMERA_HW_i2C_init(void){....if (platform_driver_register(&g_stCAMERA_HW_Driver)) //注册主摄platform 驱动if (platform_driver_register(&g_stCAMERA_HW_Driver2)) //注册副摄platform 驱动....return 0;}

主摄平台驱动的定义：

#ifdef CONFIG_OFstatic const struct of_device_id CAMERA_HW_of_ids[] = {{.compatible = "mediatek,camera_hw",},  //主摄匹配规则{}};#endifstatic struct platform_driver g_stCAMERA_HW_Driver = {.probe = CAMERA_HW_probe,.remove = CAMERA_HW_remove,.suspend = CAMERA_HW_suspend,.resume = CAMERA_HW_resume,.driver = {   .name = "image_sensor",   .owner = THIS_MODULE,#ifdef CONFIG_OF   .of_match_table = CAMERA_HW_of_ids,#endif   }};

副摄平台驱动的定义：

#ifdef CONFIG_OFstatic const struct of_device_id CAMERA_HW2_of_ids[] = {{.compatible = "mediatek,camera_hw2",},//副摄匹配规则{}};#endifstatic struct platform_driver g_stCAMERA_HW_Driver2 = {.probe = CAMERA_HW_probe2,.remove = CAMERA_HW_remove2,.suspend = CAMERA_HW_suspend2,.resume = CAMERA_HW_resume2,.driver = {   .name = "image_sensor_bus2",   .owner = THIS_MODULE,#ifdef CONFIG_OF   .of_match_table = CAMERA_HW2_of_ids,#endif}};

主副摄cam在dts中定义设备信息：

kd_camera_hw1:kd_camera_hw1@15008000 {compatible = "mediatek,camera_hw"; //这里必须和主摄一致reg = <0x15008000 0x1000>;  /* SENINF_ADDR */vcama-supply = <&mt_pmic_vcama_ldo_reg>;vcamd-supply = <&mt_pmic_vcamd_ldo_reg>;vcamaf-supply = <&mt_pmic_vcamaf_ldo_reg>;vcamio-supply = <&mt_pmic_vcamio_ldo_reg>;};kd_camera_hw2:kd_camera_hw2@15008000 {compatible = "mediatek,camera_hw2"; //这里必须和副摄一致reg = <0x15008000 0x1000>;  /* SENINF_ADDR */};

       当内核启动后，会解析dts编译生成的dtb文件，注册里面定义的device,如果和驱动中定义id一致，则挂载启动。

上面注册了两个platform 驱动g_stCAMERA_HW_Driver，g_stCAMERA_HW_Driver2，如果匹配成功会调用各自的

probe函数CAMERA_HW_probe，CAMERA_HW_probe2

2. 平台probe 函数的实现
主摄probe，CAMERA_HW_probe的实现如下：

static int CAMERA_HW_probe(struct platform_device *pdev){#if !defined(CONFIG_MTK_LEGACY)mtkcam_gpio_init(pdev);    mtkcam_pin_mux_init(pdev);#endifreturn i2c_add_driver(&CAMERA_HW_i2c_driver);}

副摄probe，CAMERA_HW_probe的实现如下：

static int CAMERA_HW_probe2(struct platform_device *pdev){return i2c_add_driver(&CAMERA_HW_i2c_driver2);}

从上可以看出在main/sub 的平台probe中分别注册了各自的i2c驱动CAMERA_HW_i2c_driver，
CAMERA_HW_i2c_driver2，main sensor 的CAMERA_HW_i2c_driver定义如下：

#ifdef CONFIG_OFstatic const struct of_device_id CAMERA_HW_i2c_of_ids[] = {    { .compatible = "mediatek,camera_main", },{}};#endifstruct i2c_driver CAMERA_HW_i2c_driver = {.probe = CAMERA_HW_i2c_probe,.remove = CAMERA_HW_i2c_remove,.driver = {   .name = CAMERA_HW_DRVNAME1,   .owner = THIS_MODULE,#ifdef CONFIG_OF   .of_match_table = CAMERA_HW_i2c_of_ids,#endif   },.id_table = CAMERA_HW_i2c_id,};sub sensor 的CAMERA_HW_i2c_driver定义如下：#ifdef CONFIG_OF    static const struct of_device_id CAMERA_HW2_i2c_driver_of_ids[] = {{ .compatible = "mediatek,camera_sub", },{}    };#endifstruct i2c_driver CAMERA_HW_i2c_driver2 = {    .probe = CAMERA_HW_i2c_probe2,    .remove = CAMERA_HW_i2c_remove2,    .driver = {    .name = CAMERA_HW_DRVNAME2,    .owner = THIS_MODULE,#ifdef CONFIG_OF    .of_match_table = CAMERA_HW2_i2c_driver_of_ids,#endif   },.id_table = CAMERA_HW_i2c_id2,};

对应main/sub camera i2c 设备dts定义如下
文件：kernel-3.18/arch/arm/boot/dts/cust_i2c.dtsi

&i2c0 {camera_main@10 {compatible = "mediatek,camera_main"; //和 CAMERA_HW_i2c_driver定义的一致reg = <0x10>;};camera_main_af@0c {compatible = "mediatek,camera_main_af";reg = <0x0c>;};camera_sub@3c {compatible = "mediatek,camera_sub"; //和CAMERA_HW_i2c_driver2定义的一致reg = <0x3c>;};};

3. I2c probe的实现

从上可以看出main/sub sensor在各自的平台probe中，注册了i2c_driver,当各自的i2c_driver和设备匹配

（如何匹配本章不作分析）成功后，会调用各自的i2c_probe函数。main sensor 的probe函数
CAMERA_HW_i2c_probe：

static int CAMERA_HW_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id){...../* Register char driver */i4RetValue = RegisterCAMERA_HWCharDrv();.....return 0;}

sub sensor 的probe函数CAMERA_HW_i2c_probe2：

static int CAMERA_HW_i2c_probe2(struct i2c_client *client, const struct i2c_device_id *id){...../* Register char driver */i4RetValue = RegisterCAMERA_HWCharDrv2();.....}

       从上可以看出main/sub 在各自的i2cprobe中，通过该调用RegisterCAMERA_HWCharDrv，RegisterCAMERA_HWCharDrv2注册了字符设备。各自注册cdev函数实现如下：

static inline int RegisterCAMERA_HWCharDrv(void)//main sensor 注册cdev{...../* Attatch file operation. */cdev_init(g_pCAMERA_HW_CharDrv, &g_stCAMERA_HW_fops); //初始化字符设备/* Add to system */cdev_add(g_pCAMERA_HW_CharDrv, g_CAMERA_HWdevno, 1) //注册到内核//创建目录 /sys/class/sensordrv/sensor_class = class_create(THIS_MODULE, "sensordrv"); //创建目录/sys/class/sensordrv/kd_camera_hw sensor_device = device_create(sensor_class, NULL, g_CAMERA_HWdevno, NULL, CAMERA_HW_DRVNAME1); ....return 0;}static inline int RegisterCAMERA_HWCharDrv2(void)//sub sensor 注册cdev{..../* Attatch file operation. */cdev_init(g_pCAMERA_HW_CharDrv2, &g_stCAMERA_HW_fops0);//初始化字符设备 /* Add to system */cdev_add(g_pCAMERA_HW_CharDrv2, g_CAMERA_HWdevno2, 1));//注册到内核//创建目录 /sys/class/sensordrv2/sensor2_class = class_create(THIS_MODULE, "sensordrv2");//创建目录/sys/class/sensordrv2/kd_camera_hw_bus2sensor_device2 = device_create(sensor2_class, NULL, g_CAMERA_HWdevno2, NULL, CAMERA_HW_DRVNAME2);....return 0;}main/sub 创建各自的字符设备过程中绑定各自的fops,g_stCAMERA_HW_fops和g_stCAMERA_HW_fops0他们各自定义如下static const struct file_operations g_stCAMERA_HW_fops = { //main sensor fops.owner = THIS_MODULE,.open = CAMERA_HW_Open,.release = CAMERA_HW_Release,.unlocked_ioctl = CAMERA_HW_Ioctl,#ifdef CONFIG_COMPAT.compat_ioctl = CAMERA_HW_Ioctl_Compat,#endif};static const struct file_operations g_stCAMERA_HW_fops0 = { //sub sensor fops.owner = THIS_MODULE,.open = CAMERA_HW_Open2,.release = CAMERA_HW_Release2,.unlocked_ioctl = CAMERA_HW_Ioctl,#ifdef CONFIG_COMPAT.compat_ioctl = CAMERA_HW_Ioctl_Compat,#endif};

从上可以看出各自的fops指定了相同的Iioctl函数，意味着上层操作main/sub sensor 只需要对应一个底层

的ioctl即可，至于sensor的区分可以借助idx,后面会讲到

/******************************************************************************** CAMERA_HW_Ioctl********************************************************************************/static long CAMERA_HW_Ioctl(struct file *a_pstFile,    unsigned int a_u4Command, unsigned long a_u4Param){...pIdx = (u32 *) pBuff;switch (a_u4Command) {...case KDIMGSENSORIOC_X_SET_DRIVER:i4RetValue = kdSetDriver((unsigned int *)pBuff);break;case KDIMGSENSORIOC_X_FEATURECONCTROL:i4RetValue = adopt_CAMERA_HW_FeatureControl(pBuff);break;case KDIMGSENSORIOC_T_CHECK_IS_ALIVE:i4RetValue = adopt_CAMERA_HW_CheckIsAlive();break;....default:PK_DBG("No such command\n");i4RetValue = -EPERM;break;}.....}

这里ioctl和上层一一对应，上层要控制caemra 只需要传入相应的cmd和data而已

============================== HAL 调用Kernel 层驱动的逻辑 ========================
       前面介绍了HAL层调用ioctl 和 kernel层注册驱动，接下来继续分析，HAL层调用后驱动具体的实现流程。
4. ioctl 底层的实现
4.1先来看ioctl(m_fdSensor, KDIMGSENSORIOC_X_SET_DRIVER,&id[KDIMGSENSOR_INVOKE_DRIVER_0] );
当KDIMGSENSORIOC_X_SET_DRIVER被传下时，会调用kernel层的kdSetDriver接口

int kdSetDriver(unsigned int *pDrvIndex){...kdGetSensorInitFuncList(&pSensorList))   //获得sensor初始化列表for (i = KDIMGSENSOR_INVOKE_DRIVER_0; i < KDIMGSENSOR_MAX_INVOKE_DRIVERS; i++) {....pSensorList[drvIdx[i]].SensorInit(&g_pInvokeSensorFunc[i]); //获取各个cam驱动中Init函数入口....}return 0;}

kdGetSensorInitFuncList的实现：

UINT32 kdGetSensorInitFuncList(ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT **ppSensorList){if (NULL == ppSensorList) {PK_ERR("[kdGetSensorInitFuncList]ERROR: NULL ppSensorList\n");return 1;}*ppSensorList = &kdSensorList[0];  //获取sensorlist数组首地址return 0;}/* kdGetSensorInitFuncList() */

kdSensorList定义如下：
文件：kernel-3.18/drivers/misc/mediatek/imgsensor/src/mt6580/kd_sensorlist.h

ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT kdSensorList[MAX_NUM_OF_SUPPORT_SENSOR+1] ={....#if defined(SUB_GC2355_MIPI_RAW)    {GC2355S_SENSOR_ID, SENSOR_DRVNAME_GC2355S_MIPI_RAW,Sub_GC2355_MIPI_RAW_SensorInit},#endif....}

获取列表之后紧接着调用各自的Init函数,这里以GC2355为例

UINT32 GC2235MIPI_RAW_SensorInit(PSENSOR_FUNCTION_STRUCT *pfFunc){/* To Do : Check Sensor status here */if (pfFunc!=NULL)*pfFunc=&sensor_func;return ERROR_NONE;}/*GC2235MIPI_RAW_SensorInit*/

     丛中可以看出，gc2355的Init函数地址传给了pfFunc，也就是时候，后面在通用驱动可以直接凭借

pfun指针调用sensorlist中的驱动
4.2 再来看ioctl(m_fdSensor, KDIMGSENSORIOC_T_CHECK_IS_ALIVE);

当KDIMGSENSORIOC_T_CHECK_IS_ALIVE被传下时，会调用kernel层的adopt_CAMERA_HW_Feature

Control接口

static inline int adopt_CAMERA_HW_CheckIsAlive(void){..../* power on sensor */kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM *) g_invokeSocketIdx, g_invokeSensorNameStr,true, CAMERA_HW_DRVNAME1);....if (g_pSensorFunc) {for (i = KDIMGSENSOR_INVOKE_DRIVER_0; i < KDIMGSENSOR_MAX_INVOKE_DRIVERS; i++) {if (DUAL_CAMERA_NONE_SENSOR != g_invokeSocketIdx[i]) {err =    g_pSensorFunc->SensorFeatureControl(g_invokeSocketIdx[i],SENSOR_FEATURE_CHECK_SENSOR_ID,(MUINT8 *) &sensorID,&retLen);if (sensorID == 0) {/* not implement this feature ID */PK_DBG    (" Not implement!!, use old open function to check\n");err = ERROR_SENSOR_CONNECT_FAIL;} else if (sensorID == 0xFFFFFFFF) {/* fail to open the sensor */PK_DBG(" No Sensor Found");err = ERROR_SENSOR_CONNECT_FAIL;} else {PK_INF(" Sensor found ID = 0x%x\n", sensorID);snprintf(mtk_ccm_name, sizeof(mtk_ccm_name), "%s CAM[%d]:%s;", mtk_ccm_name, g_invokeSocketIdx[i], g_invokeSensorNameStr[i]);psensorResolution[0] = &sensorResolution[0];psensorResolution[1] = &sensorResolution[1];// don't care of the resultg_pSensorFunc->SensorGetResolution(psensorResolution);if(g_invokeSocketIdx[i] == DUAL_CAMERA_MAIN_SENSOR)curr_sensor_id = 0;else if(g_invokeSocketIdx[i] == DUAL_CAMERA_SUB_SENSOR)curr_sensor_id = 1;/* fill the cam infos with name/width/height */snprintf(g_cam_infos, sizeof(g_cam_infos),"%s CAM[%d]:%s,Width:%d, Height:%d;",g_cam_infos, g_invokeSocketIdx[i], g_invokeSensorNameStr[i],sensorResolution[curr_sensor_id].SensorFullWidth, sensorResolution[curr_sensor_id].SensorFullHeight);err = ERROR_NONE;}if (ERROR_NONE != err) {PK_DBG    ("ERROR:adopt_CAMERA_HW_CheckIsAlive(), No imgsensor alive\n");}}}} else {PK_DBG("ERROR:NULL g_pSensorFunc\n");}}/* adopt_CAMERA_HW_Open() */

这个函数非常重要，它主要进行了以下几个动作，
1）通过kdModulePowerOn给Sensor上电
2）通过SensorFeatureControl读取SensorID 
先看kdModulePowerOn的实现

intkdModulePowerOn(CAMERA_DUAL_CAMERA_SENSOR_ENUM socketIdx[KDIMGSENSOR_MAX_INVOKE_DRIVERS],char sensorNameStr[KDIMGSENSOR_MAX_INVOKE_DRIVERS][32], BOOL On, char *mode_name){MINT32 ret = ERROR_NONE;u32 i = 0;for (i = KDIMGSENSOR_INVOKE_DRIVER_0; i < KDIMGSENSOR_MAX_INVOKE_DRIVERS; i++) {if (g_bEnableDriver[i]) {/* PK_XLOG_INFO("[%s][%d][%d][%s][%s]\r\n",__FUNCTION__,g_bEnableDriver[i],socketIdx[i],sensorNameStr[i],mode_name); */#ifndef CONFIG_FPGA_EARLY_PORTINGret = _kdCISModulePowerOn(socketIdx[i], sensorNameStr[i], On, mode_name);#endifif (ERROR_NONE != ret) {PK_ERR("[%s]", __func__);return ret;}}}return ERROR_NONE;}

在kdModulePowerOn中又调用_kdCISModulePowerOn

int _kdCISModulePowerOn(CAMERA_DUAL_CAMERA_SENSOR_ENUM SensorIdx, char *currSensorName, BOOL On,char *mode_name){....ret = kdCISModulePowerOn(SensorIdx, currSensorName, On, mode_name);....return ret;}

在_kdCISModulePowerOn又调用kdCISModulePowerOn函数
文件：kernel-3.18/drivers/misc/mediatek/imgsensor/src/mt6580/camera_hw/kd_camera_hw.c
//改函数为上下电函数，通过传入BOOL值来判断上/下电

int kdCISModulePowerOn(CAMERA_DUAL_CAMERA_SENSOR_ENUM SensorIdx, char *currSensorName, BOOL On,       char *mode_name){u32 pinSetIdx = 0;/* default main sensor */#define IDX_PS_CMRST 0#define IDX_PS_CMPDN 4#define IDX_PS_MODE 1#define IDX_PS_ON   2#define IDX_PS_OFF  3#define VOL_2800 2800000#define VOL_1800 1800000#define VOL_1500 1500000#define VOL_1200 1200000#define VOL_1000 1000000u32 pinSet[3][8] = {/* for main sensor */{/* The reset pin of main sensor uses GPIO10 of mt6306, please call mt6306 API to set */ CAMERA_CMRST_PIN, CAMERA_CMRST_PIN_M_GPIO,/* mode */ GPIO_OUT_ONE,/* ON state */ GPIO_OUT_ZERO,/* OFF state */ CAMERA_CMPDN_PIN, CAMERA_CMPDN_PIN_M_GPIO, GPIO_OUT_ONE, GPIO_OUT_ZERO, },/* for sub sensor */{ CAMERA_CMRST1_PIN, CAMERA_CMRST1_PIN_M_GPIO, GPIO_OUT_ONE, GPIO_OUT_ZERO, CAMERA_CMPDN1_PIN, CAMERA_CMPDN1_PIN_M_GPIO, GPIO_OUT_ONE, GPIO_OUT_ZERO, },/* for main_2 sensor */{ GPIO_CAMERA_INVALID, GPIO_CAMERA_INVALID,/* mode */ GPIO_OUT_ONE,/* ON state */ GPIO_OUT_ZERO,/* OFF state */ GPIO_CAMERA_INVALID, GPIO_CAMERA_INVALID, GPIO_OUT_ONE, GPIO_OUT_ZERO, }};if (DUAL_CAMERA_MAIN_SENSOR == SensorIdx)pinSetIdx = 0;else if (DUAL_CAMERA_SUB_SENSOR == SensorIdx)pinSetIdx = 1;else if (DUAL_CAMERA_MAIN_2_SENSOR == SensorIdx)pinSetIdx = 2;/* power ON */if (On) {#if 0ISP_MCLK1_EN(1);ISP_MCLK2_EN(1);ISP_MCLK3_EN(1);#elseif (pinSetIdx == 0)ISP_MCLK1_EN(1);else if (pinSetIdx == 1)ISP_MCLK2_EN(1);#endifprintk("fangkuiccm %d ,currSensorName = %s pinSetIdx = %d ",__LINE__,currSensorName,pinSetIdx );//通过DriverName来区分SensorIC    if (currSensorName && (0 == strcmp(SENSOR_DRVNAME_GC2355_MIPI_RAW, currSensorName))) {/* First Power Pin low and Reset Pin Low */if (GPIO_CAMERA_INVALID != pinSet[pinSetIdx][IDX_PS_CMPDN])mtkcam_gpio_set(pinSetIdx, CAMPDN,pinSet[pinSetIdx][IDX_PS_CMPDN + IDX_PS_OFF]);if (GPIO_CAMERA_INVALID != pinSet[pinSetIdx][IDX_PS_CMRST])mtkcam_gpio_set(pinSetIdx, CAMRST,pinSet[pinSetIdx][IDX_PS_CMRST + IDX_PS_OFF]);mdelay(50);/* VCAM_A */if (TRUE != _hwPowerOn(VCAMA, VOL_2800)) {PK_DBG    ("[CAMERA SENSOR] Fail to enable analog power (VCAM_A),power id = %d\n",     VCAMA);goto _kdCISModulePowerOn_exit_;}mdelay(10);/* VCAM_IO */if (TRUE != _hwPowerOn(VCAMIO, VOL_1800)) {PK_DBG    ("[CAMERA SENSOR] Fail to enable IO power (VCAM_IO),power id = %d\n",     VCAMIO);goto _kdCISModulePowerOn_exit_;}mdelay(10);if (TRUE != _hwPowerOn(VCAMD, VOL_1500)) {PK_DBG    ("[CAMERA SENSOR] Fail to enable digital power (VCAM_D),power id = %d\n",     VCAMD);goto _kdCISModulePowerOn_exit_;}mdelay(10);/* AF_VCC */if (TRUE != _hwPowerOn(VCAMAF, VOL_2800)) {PK_DBG    ("[CAMERA SENSOR] Fail to enable analog power (VCAM_AF),power id = %d\n",     VCAMAF);goto _kdCISModulePowerOn_exit_;}mdelay(50);if (GPIO_CAMERA_INVALID != pinSet[pinSetIdx][IDX_PS_CMRST]) {mtkcam_gpio_set(pinSetIdx, CAMRST,pinSet[pinSetIdx][IDX_PS_CMRST + IDX_PS_OFF]);mdelay(5);mtkcam_gpio_set(pinSetIdx, CAMRST,pinSet[pinSetIdx][IDX_PS_CMRST + IDX_PS_ON]);}mdelay(5);/* enable active sensor */if (GPIO_CAMERA_INVALID != pinSet[pinSetIdx][IDX_PS_CMPDN]) {mtkcam_gpio_set(pinSetIdx, CAMPDN,pinSet[pinSetIdx][IDX_PS_CMPDN + IDX_PS_ON]);mdelay(5);mtkcam_gpio_set(pinSetIdx, CAMPDN,pinSet[pinSetIdx][IDX_PS_CMPDN + IDX_PS_OFF]);}mdelay(5);}     }else{ //poweroff if (currSensorName   //上完电就要下电不然会造成漏电，最终会影响手机功耗   && (0 == strcmp(SENSOR_DRVNAME_GC2355_MIPI_RAW, currSensorName))) {#if 0mt_set_gpio_mode(GPIO_SPI_MOSI_PIN, GPIO_MODE_00);mt_set_gpio_dir(GPIO_SPI_MOSI_PIN, GPIO_DIR_OUT);mt_set_gpio_out(GPIO_SPI_MOSI_PIN, GPIO_OUT_ONE);#endif/* First Power Pin low and Reset Pin Low */if (GPIO_CAMERA_INVALID != pinSet[pinSetIdx][IDX_PS_CMPDN]) {if (mt_set_gpio_mode    (pinSet[pinSetIdx][IDX_PS_CMPDN],     pinSet[pinSetIdx][IDX_PS_CMPDN + IDX_PS_MODE])) {PK_DBG("[CAMERA LENS] set gpio mode failed!! (CMPDN)\n");}if (mt_set_gpio_dir(pinSet[pinSetIdx][IDX_PS_CMPDN], GPIO_DIR_OUT)) {PK_DBG("[CAMERA LENS] set gpio dir failed!! (CMPDN)\n");}if (mt_set_gpio_out    (pinSet[pinSetIdx][IDX_PS_CMPDN],     pinSet[pinSetIdx][IDX_PS_CMPDN + IDX_PS_OFF])) {PK_DBG("[CAMERA LENS] set gpio failed!! (CMPDN)\n");}}}}

上电操作完成后，紧接着读取SensorID，通用驱动使用SensorFeatureControl来读取ID如：
 g_pSensorFunc->SensorFeatureControl(g_invokeSocketIdx[i],
SENSOR_FEATURE_CHECK_SENSOR_ID,
(MUINT8 *) &sensorID,
&retLen);
这步操作会调用GC2355中的feature_control函数如下：
文件：kernel-3.18/drivers/misc/mediatek/imgsensor/src/mt6580/gc2355_mipi_raw/gc2355mipi_Sensor.c

static kal_uint32 feature_control(MSDK_SENSOR_FEATURE_ENUM feature_id,                             UINT8 *feature_para,UINT32 *feature_para_len){....    LOG_INF("feature_id = %d\n", feature_id);    switch (feature_id) {....        case SENSOR_FEATURE_CHECK_SENSOR_ID:            get_imgsensor_id(feature_return_para_32);            break;....        default:            break;    }    return ERROR_NONE;}    

优化传入的cmd为SENSOR_FEATURE_CHECK_SENSOR_ID，则会调用feature_control中的

get_imgsensor_id再看get_imgsensor_id的实现

static kal_uint32 get_imgsensor_id(UINT32 *sensor_id){    kal_uint8 i = 0;    kal_uint8 retry = 2;    //sensor have two i2c address 0x6c 0x6d & 0x21 0x20, we should detect the module used i2c address    while (imgsensor_info.i2c_addr_table[i] != 0xff) {        spin_lock(&imgsensor_drv_lock);        imgsensor.i2c_write_id = imgsensor_info.i2c_addr_table[i];        spin_unlock(&imgsensor_drv_lock);        do {            *sensor_id = return_sensor_id(); //return_sensor_id读取IC的ID            if (*sensor_id == imgsensor_info.sensor_id) {                LOG_INF("i2c write id: 0x%x, sensor id: 0x%x\n", imgsensor.i2c_write_id,*sensor_id);                return ERROR_NONE;            }            LOG_INF("Read sensor id fail, write id: 0x%x, id: 0x%x\n", imgsensor.i2c_write_id,*sensor_id);            retry--;        } while(retry > 0);        i++;        retry = 2;    }....    return ERROR_NONE;}

再看return_sensor_id的实现

static kal_uint32 return_sensor_id(void){    return ((read_cmos_sensor(0xf0) << 8) | read_cmos_sensor(0xf1));}static kal_uint16 read_cmos_sensor(kal_uint32 addr){kal_uint16 get_byte=0;char pu_send_cmd[1] = {(char)(addr & 0xFF) };iReadRegI2C(pu_send_cmd, 1, (u8*)&get_byte, 1, imgsensor.i2c_write_id);return get_byte;}

文件：kernel-3.18/drivers/misc/mediatek/imgsensor/src/mt6580/kd_sensorlist.c

int iReadRegI2C(u8 *a_pSendData, u16 a_sizeSendData, u8 *a_pRecvData, u16 a_sizeRecvData,u16 i2cId){int i4RetValue = 0;if (gI2CBusNum == SUPPORT_I2C_BUS_NUM1) {spin_lock(&kdsensor_drv_lock);g_pstI2Cclient->addr = (i2cId >> 1);g_pstI2Cclient->ext_flag = (g_pstI2Cclient->ext_flag) & (~I2C_DMA_FLAG);/* Remove i2c ack error log during search sensor *//* PK_ERR("g_pstI2Cclient->ext_flag: %d", g_IsSearchSensor); */if (g_IsSearchSensor == 1) {g_pstI2Cclient->ext_flag = (g_pstI2Cclient->ext_flag) | I2C_A_FILTER_MSG;} else {g_pstI2Cclient->ext_flag = (g_pstI2Cclient->ext_flag) & (~I2C_A_FILTER_MSG);}spin_unlock(&kdsensor_drv_lock);/*  */i4RetValue = i2c_master_send(g_pstI2Cclient, a_pSendData, a_sizeSendData);if (i4RetValue != a_sizeSendData) {PK_ERR("[CAMERA SENSOR] I2C send failed!!, Addr = 0x%x\n", a_pSendData[0]);return -1;}i4RetValue = i2c_master_recv(g_pstI2Cclient, (char *)a_pRecvData, a_sizeRecvData);if (i4RetValue != a_sizeRecvData) {PK_ERR("[CAMERA SENSOR] I2C read failed!!\n");return -1;}} else {spin_lock(&kdsensor_drv_lock);g_pstI2Cclient2->addr = (i2cId >> 1);/* Remove i2c ack error log during search sensor *//* PK_ERR("g_pstI2Cclient2->ext_flag: %d", g_IsSearchSensor); */if (g_IsSearchSensor == 1) {g_pstI2Cclient2->ext_flag = (g_pstI2Cclient2->ext_flag) | I2C_A_FILTER_MSG;} else {g_pstI2Cclient2->ext_flag = (g_pstI2Cclient2->ext_flag) & (~I2C_A_FILTER_MSG);}spin_unlock(&kdsensor_drv_lock);i4RetValue = i2c_master_send(g_pstI2Cclient2, a_pSendData, a_sizeSendData);if (i4RetValue != a_sizeSendData) {PK_ERR("[CAMERA SENSOR] I2C send failed!!, Addr = 0x%x\n", a_pSendData[0]);return -1;}i4RetValue = i2c_master_recv(g_pstI2Cclient2, (char *)a_pRecvData, a_sizeRecvData);if (i4RetValue != a_sizeRecvData) {PK_ERR("[CAMERA SENSOR] I2C read failed!!\n");return -1;}}return 0;}

      这一步完成I2c的读取，也就是说如果I2c配置正确，并且上电正确，到这一步就可以正确的读取ID，

整个camera也就基本就调通了。

三、总结

     通过上述分析，我们可以看出，camera驱动先是注册平台驱动，再注册I2c驱动，然后又为前后摄

注册字符设备，封装底层方法，上层访问底层驱动时候显示使用setdriver将具体IC的驱动入口获取，

然后使用checkisalive对sensorlist中的IC进行上电，上电完成就读取设备ID，到此为止，上层应用与

底层驱动挂接完成，紧接着就是预览和拍照，不过这都是具体IC驱动的实现了。