MTK6577---camera驱动分析

原文地址：http://blog.chinaunix.net/uid-26009923-id-3999723.html

一.camera驱动的初始化
1. 支持的摄像头列表
在./mediatek/config/mobitek77_m01_ics2/ProjectConfig.mk中,
配置支持的摄像头驱动

CUSTOM_HAL_IMGSENSOR=ov5640_yuv s5k4e1ga_raw ov5647_raw gc2035_yuv gc0329_yuv
CUSTOM_HAL_MAIN_IMGSENSOR=ov5640_yuv s5k4e1ga_raw ov5647_raw #gc2035_yuv
CUSTOM_HAL_SUB_IMGSENSOR=gc2035_yuv gc0329_yuv
CUSTOM_KERNEL_IMGSENSOR=ov5640_yuv s5k4e1ga_raw ov5647_raw gc2035_yuv gc0329_yuv
CUSTOM_KERNEL_SUB_IMGSENSOR=gc2035_yuv gc0329_yuv

在 custom/common/kernel/imgsensor/src/kd_sensorlist.h或
在source/external/mhal/src/custom/common/kernel/imgsensor/kd_sensorlist.h 中

ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT kdSensorList[] =
{
#if defined(GC2035_YUV)
        {GC2035_SENSOR_ID, SENSOR_DRVNAME_GC2035_YUV, GC2035_YUV_SensorInit},
#endif
#if defined(OV5640_YUV)
    {OV5640_SENSOR_ID, SENSOR_DRVNAME_OV5640_YUV, OV5640_YUV_SensorInit},
#endif
    {0,{0},NULL},
};

2. module_init
在mediatek\custom\common\kernel\imgsensor\src\kd_sensorlist.c中
module_init(CAMERA_HW_i2C_init);
//文件的开头,先声明I2C信息
static struct i2c_board_info __initdata kd_camera_dev={ I2C_BOARD_INFO("kd_camera_hw", 0xfe>>1)};

static int __init CAMERA_HW_i2C_init(void)
{
    //注册i2c信息,下一步就可以调用i2c_add_driver
    i2c_register_board_info(CAMERA_I2C_BUSNUM, &kd_camera_dev, 1);
    //注册platform_driver然后调用probe函数CAMERA_HW_probe
    platform_driver_register(&g_stCAMERA_HW_Driver);
    //在proc目录中创建/proc/driver/camsensor调试信息
    prEntry = create_proc_entry("driver/camsensor", 0, NULL);
    prEntry->read_proc = CAMERA_HW_DumpReg_To_Proc;
    prEntry->write_proc = CAMERA_HW_Reg_Debug;

    //全局变量的初始化
    atomic_set(&g_CamHWOpend, 0);
    atomic_set(&g_CamDrvOpenCnt, 0);
    atomic_set(&g_CamHWOpening, 0);
}

3. Camera_hw_p
CAMERA_HW_i2C_init
    --> platform_driver_register 
        --> CAMERA_HW_probe
        --> i2c_add_driver
在mediatek\custom\common\kernel\imgsensor\src\kd_sensorlist.c中

static int CAMERA_HW_probe(struct platform_device *pdev)
{
    //创建一个等侍队列
    init_waitqueue_head(&kd_sensor_wait_queue);
    //注册一个i2c驱动,然后调用i2c驱动的probe函数CAMERA_HW_i2c_probe
    return i2c_add_driver(&CAMERA_HW_i2c_driver);
}

4. Camera_hw_i2c_probe
CAMERA_HW_i2C_init
    --> platform_driver_register 
        --> CAMERA_HW_probe
        --> i2c_add_driver
                --> CAMERA_HW_i2c_probe
在mediatek\custom\common\kernel\imgsensor\src\kd_sensorlist.c中
static DEFINE_SPINLOCK(kdsensor_drv_lock); //spin_lock的初始化是在全局变量中初始化的

static int CAMERA_HW_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    spin_lock(&kdsensor_drv_lock);           //加锁
    g_pstI2Cclient = client;        //获取client
    g_pstI2Cclient->timing = 200;   //设置clock 200k
    spin_unlock(&kdsensor_drv_lock);         //解锁

    i4RetValue = RegisterCAMERA_HWCharDrv();   //字符设备的初始化
}

4.1 字符设备初始化
#define CAMERA_HW_DRVNAME "kd_camera_hw"
static dev_t g_CAMERA_HWdevno = MKDEV(250,0);

inline static int RegisterCAMERA_HWCharDrv(void)
{
    struct device* sensor_device = NULL;

#if CAMERA_HW_DYNAMIC_ALLOCATE_DEVNO
    alloc_chrdev_region(&g_CAMERA_HWdevno, 0, 1,CAMERA_HW_DRVNAME); //动态分配dev_no
#else
    register_chrdev_region( g_CAMERA_HWdevno , 1 , CAMERA_HW_DRVNAME);
#endif

    g_pCAMERA_HW_CharDrv = cdev_alloc();                   //分配设备内存
    cdev_init(g_pCAMERA_HW_CharDrv, &g_stCAMERA_HW_fops);  //初始化设备
    g_pCAMERA_HW_CharDrv->owner = THIS_MODULE;
    cdev_add(g_pCAMERA_HW_CharDrv, g_CAMERA_HWdevno, 1))   //注册设备
    //这样就创建了结点/dev/kd_camera_hw
    sensor_class = class_create(THIS_MODULE, "sensordrv");     //与下一句一起创建设备结点
    sensor_device = device_create(sensor_class, NULL, g_CAMERA_HWdevno, NULL, CAMERA_HW_DRVNAME);

}

字符设备的文件操作

static const struct file_operations g_stCAMERA_HW_fops =
{
    .owner = THIS_MODULE,
    .open = CAMERA_HW_Open,
    .release = CAMERA_HW_Release,
#ifdef HAL_CAMERA_COMPATIBLE
    .read = device_read,
#endif
    #ifdef USE_NEW_IOCTL
    .unlocked_ioctl = CAMERA_HW_Ioctl
    #else
    .ioctl = CAMERA_HW_Ioctl
    #endif
};

5. 字符设备的open与relase
open与relase函数啥也不作,只是把计数加1或减1

static int CAMERA_HW_Open(struct inode * a_pstInode, struct file * a_pstFile)
{
    dbmsg("open");
    atomic_inc(&g_CamDrvOpenCnt);
    return 0;
}

release:

static int CAMERA_HW_Release(struct inode * a_pstInode, struct file * a_pstFile)
{
    atomic_dec(&g_CamDrvOpenCnt);

    return 0;
}

5. 字符设备的read过程
在./mediatek/config/mobitek77_m01_ics2/ProjectConfig.mk中
CUSTOM_HAL_IMGSENSOR=ov5640_yuv s5k4e1ga_raw ov5647_raw  gc2035_yuv gc0329_yuv
在mediatek\custom\common\hal\imgsensor\src\sensorlist.cpp中

MSDK_SENSOR_INIT_FUNCTION_STRUCT SensorList[] =
{
    #if defined(OV5640_YUV)
        YUV_INFO(OV5640_SENSOR_ID, SENSOR_DRVNAME_OV5640_YUV, NULL),
    #endif
    #if defined(S5K4E1GA_RAW)
        RAW_INFO(S5K4E1GA_SENSOR_ID, SENSOR_DRVNAME_S5K4E1GA_RAW, NULL),
    #endif
    #if defined(OV5647_RAW)
        RAW_INFO(OV5647_SENSOR_ID, SENSOR_DRVNAME_OV5647_RAW, NULL),
    #endif
    #if defined(GC2035_YUV)
        YUV_INFO(GC2035_SENSOR_ID, SENSOR_DRVNAME_GC2035_YUV,NULL),
    #endif
    #if defined(GC0329_YUV)
        YUV_INFO(GC0329_SENSOR_ID, SENSOR_DRVNAME_GC0329_YUV, NULL),
    #endif
    {0,{0},NULL, NULL, NULL}//end of list
};

在mediatek\custom\common\kernel\imgsensor\src\kd_sensorlist.c

static ssize_t device_read(struct file *filp, char *buffer, size_t length, loff_t *offset)
{
    int bytes_read = 0;
    char i,k,j,g,err;
    char msg[2]={0};//"pangfei read test program";

    //查看sensorList中的支持的驱动数目
    k = sizeof(kdSensorList)/sizeof(ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT) - 1;
    //寻找主摄像头
    for(i=0;i<k;i++)
    {
        kdSearchCameraDriver(i,DUAL_CAMERA_MAIN_SENSOR); //5.1检查是否有这个驱动的硬件
        msg[0] = i;
        MainCameraDrvIdx = i;    //如果有将全局变量MainCameraDrvIdx设为找到的值,这儿为0
        break;                   //这儿为0,即主摄像头是在SensorList中的第0项:ov5640_yuv
     }
    //寻找次摄像头
    for(j=k-1;j>msg[0];j--)
    {
        err=kdSearchCameraDriver(j,DUAL_CAMERA_SUB_SENSOR);  //检查是否有这个驱动的硬件
        msg[1] = j;
        SubCameraDrvIdx = j;     //如果有将全局变量SubCameraDrvIdx设为找到的值,这儿为3
        break;                   //这儿为0,即次摄像头是在SensorList中的第3项:gc2035_yuv
    }
}

5.1 寻找驱动

static int kdSearchCameraDriver(char drvIdx,char index)
{
    ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT *pSensorList = NULL;
    kdGetSensorInitFuncList(&pSensorList)); //5.1.1由pSensorList获取首地址
    pSensorList[drvIdx].SensorInit(&g_pSensorFunc);   //调用具体硬件的SensorInit
    CAMERA_HW_CheckIsAlive(index);                    //5.1.2读取sensorID是否正历来判断是否有这个驱动的硬件连上
}

5.1.1获取sensorList的首地址

UINT32 kdGetSensorInitFuncList(ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT **ppSensorList)
{
    *ppSensorList = &kdSensorList[0];
    return 0;
}

5.1.2读取器件的SensorID来判断是否有硬件连上

static int CAMERA_HW_CheckIsAlive(char index)
{
    g_currDualSensorIdx = index; //power on main or sub sensor
    kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM) g_currDualSensorIdx, g_currSensorName,true, CAMERA_HW_DRVNAME);
    mDELAY(10);
    //读取SensorID
    g_pSensorFunc->SensorFeatureControl(SENSOR_FEATURE_CHECK_SENSOR_ID, (MUINT8*)&sensorID, &retLen);
    if (sensorID == 0) { //如果读取失败,还有可能是没有实现这个接口,再用SensorOpen试试
        err = g_pSensorFunc->SensorOpen();
    }
    else if (sensorID == 0xFFFFFFFF) {
       err = ERROR_SENSOR_CONNECT_FAIL;
    }
    else {
           err = ERROR_NONE;
    }
    kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM) g_currDualSensorIdx, NULL, false, CAMERA_HW_DRVNAME);
}

int kdSetDriver(unsigned int* pDrvIndex)
{
    ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT *pSensorList = NULL;
    unsigned int drvIdx = (*pDrvIndex & KDIMGSENSOR_DUAL_MASK_LSB);
    spin_lock(&kdsensor_drv_lock);
    g_currDualSensorIdx = (CAMERA_DUAL_CAMERA_SENSOR_ENUM)((*pDrvIndex & KDIMGSENSOR_DUAL_MASK_MSB)>>KDIMGSENSOR_DUAL_SHIFT);
    spin_unlock(&kdsensor_drv_lock);
    kdGetSensorInitFuncList(&pSensorList);
    k = sizeof(kdSensorList)/sizeof(ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT) - 1;
    if (drvIdx == 0)
    {
        drvIdx = MainCameraDrvIdx;
        pSensorList[drvIdx].SensorInit(&g_pSensorFunc);     //调用init获取具体驱动的函数指针
        memcpy((char*)g_currSensorName,(char*)pSensorList[drvIdx].drvname,sizeof(pSensorList[drvIdx].drvname));
        *pDrvIndex = (unsigned int)pSensorList[drvIdx].SensorId;
    }
    else
    {
        drvIdx = SubCameraDrvIdx;
        pSensorList[drvIdx].SensorInit(&g_pSensorFunc);     //调用init获取具体驱动的函数指针
        memcpy((char*)g_currSensorName,(char*)pSensorList[drvIdx].drvname,sizeof(pSensorList[drvIdx].drvname));
        *pDrvIndex = (unsigned int)pSensorList[drvIdx].SensorId;
    }
}