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camer驱动模块加载分析

时间:2016-05-15 07:10:57      阅读:281      评论:0      收藏:0      [点我收藏+]

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       在平时工作中,camera模块是经常进行调试修改的模块,所以熟悉camera的工作流程以及工作原理将会大大的提供工作效率,但对于整个android系统camera是个十分复杂的模块,下面对camera的驱动加载进行分析。

1、 Camera成像简介

       景物通过镜头(LENS)生成的光学图像投射到图像传感器(Sensor)表面上,然后转为模拟的电信号,经过 A/D(模数转换)转换后变为数字图像信号,再送到数字信号处理芯片(DSP)中加工处理,再通过 IO 接口传输到 CPU 中处理,通过 LCD 就可以看到图像了。
       图像传感器(SENSOR)是一种半导体芯片,其表面包含有几十万到几百万的光电二极管。光电二极管受到光照射时,就会产生电荷。目前的 SENSOR 类型有两种:CCD(ChargeCouple Device)和CMOS(ComplementaryMetal Oxide Semiconductor)。CCD电荷耦合器件,它是目前高像素类 sensor 中比较成熟的成像器件,是以一行为单位的电流信号。CMOS互补金属氧化物半导体。CMOS的信号是以点为单位的电荷信号,更为敏感,速度也更快,更为省电。ISP 的性能是决定影像流畅的关键,JPEGencoder 的性能也是关键指标之一。而 JPEGencoder 又分为硬件 JPEG 压缩方式和软件 RGB压缩方式。DSP 控制芯片的作用是:将感光芯片获取的数据及时快速地传到 baseband 中并刷新感光芯片,因此控制芯片的好坏,直接决定画面品质(比如色彩饱和度、清晰度)与流畅度。

2、Camera的硬件原理图及引脚

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     从上面可看出,连接 Camera 的pin引脚可大致分为以下几类:

     2.1、 电源部分:

           a):VCAMD 就是DVDD数字供电,主要给ISP供电,由于 RAWDATA格式的sensor其ISP是在BB端,所以将其引脚将其NC。从上面的规格书上可以看出 DVDD是内部BB端供电。模组已将其 NC掉了,在MTK代码中的上电部分,DVDD电压用CAMERA_POWER_VCAM_D表示;
           b):VCAM_IO 就是 VDDIO 数字 IO 电源主要给 I2C 部分供电,在MTK代码中的上电部分,DVDD电压用CAMERA_POWER_VCAM_D2表示;
           c):VCAMA 就是 AVDD 模拟供电,主要给感光区和 ADC 部分供电,在MTK代码中的上电部分,DVDD电压用CAMERA_POWER_VCAM_A表示;
           d):VCAM_AF 是对 Camera 自动对焦马达的供电,在MTK代码中的上电部分,DVDD电压用CAMERA_POWER_VCAM_A2表示。

     2.2、 Sensor Input 部分:

           a) :Reset 信号,用于复位、初始化。

           b) :Standby/PowerDown信号,用于进入待机模式,降低功耗。

           c) :Mclk,即MasterClock 信号,是由 BB 端提供。

    2.3、Sensor OutPut 部分:

     a) :Pclk,即 PixelClock 信号,由 MCLK 分频得到,作为外部时钟控制图像传输帧率;

     b) :HSYNC,行同步信号,其上升沿表示新一列行图像数据的开始;

     c) :VSYNC,帧同步信号,其下降沿表示新的一帧图片的开始;

     d) :D0-D9 一共 10 根数据线(8/10 根等)。

     2.4、I2C 部分

        Camera也是挂载在I2C总线上的设备,主要利用I2C总线对寄存器进行一些读写,与其他该做在I2C总线上的设备一样,这部分就两根线SCL和SDA,SCL,I2C 时钟信号线和 SDA,I2C 数据信号线。
 

3、Camera架构

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        上图的架构相信大家都有了一定的了解,android 将系统大致分为应用层、库文件和硬件抽象层、Linux 内核三层。在底层的内核空间,Camera 的 driver 将其驱动起来以后,将硬件驱动的接口交给硬件抽象层,android 上层的 Camera 应用程序在 android 实时系统中的虚拟机中,加载 android 留给 Camera 公用的一些库文件,调用硬件抽象层的接口来控制 Camera硬件来实现功能。当然,如果是 Raw 模式的 Camera,还需要在硬件抽象层调用一些参数来控制 Camera 的效果。

        Kernel 部分主要有两块:一块是image sensor 驱动,负责具体型号的sensor 的id 检测,上电,以及在preview,capture,初始化,3A 等等功能设定时的寄存器配置。另一块是isp driver,通过DMA 将sensor数据流上传。

       HAL层这边主要分3 块,一块是imageio,主要是数据buffer上传的pipe。一块是drv,包含imgsensor 和isp 的hal 层控制。最后是feature io,包含各种3A 等性能配置。

4、Camera image sensor驱动模块驱动加载

        camera模块驱动是一个字符驱动,驱动是挂载在总线上,一般在 Linux 总线驱动模型中,我们只需要关心总线、设备、驱动这三个实体。总线会充当红娘对加载于其上的设备与驱动进行配对,对于 Camera 模块也不例外,下面从总线、设备、驱动的角度来分析 Camera 模块驱动的注册、匹配与加载过程。
        MTK的image_sensor注册的是一个platform类型总线驱动,首先要进行板极设备的初始化的工作,代码在:mediatek/platform/mt6572/kernel/core/mt_devs.c,里面会对platform总线注册的device进行注册:
 #if 1 ///defined(CONFIG_VIDEO_CAPTURE_DRIVERS)
     retval = platform_device_register(&sensor_dev);
     if (retval != 0){
         return retval;
     }
#endif
static struct platform_device sensor_dev = {
         .name            = "image_sensor",
        .id              = -1,
 };
      image_sensor的platform类型驱动的device的name为 "image_sensor",而在linux中,所有的总线的driver与device都是通过name来与进行匹配的,platform总线也不例外,所以可以通过grep命令来查找camera注册的总线中driver的注册路径为:mediatek/custom/common/kernel/imgsensor/src/kd_sensorlist.c,代码为:
static 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,
     }
};
       下面就来看看image_sensorplatform的driver整个注册流程是怎样实现的。先来看看kd_sensorlist.c驱动文件的init人口函数:
/*=======================================================================
  * CAMERA_HW_i2C_init()
  *=======================================================================*/
static int __init CAMERA_HW_i2C_init(void)
{
    struct proc_dir_entry *prEntry;

     //i2c_register_board_info(CAMERA_I2C_BUSNUM, &kd_camera_dev, 1);
    i2c_register_board_info(SUPPORT_I2C_BUS_NUM1, &i2c_devs1, 1); // 填充i2c的板极文件
    //i2c_register_board_info(SUPPORT_I2C_BUS_NUM2, &i2c_devs2, 1);


    if(platform_driver_register(&g_stCAMERA_HW_Driver)){ // 注册platform总线的driver
        PK_ERR("failed to register CAMERA_HW driver\n");
        return -ENODEV;
    }
    //if(platform_driver_register(&g_stCAMERA_HW_Driver2)){
    //    PK_ERR("failed to register CAMERA_HW driver\n");
    //    return -ENODEV;
    //}

    //Register proc file for main sensor register debug
    prEntry = create_proc_entry("driver/camsensor", 0, NULL); //在proc下创建driver/camsensor这个节点,用于前置摄像头进行adb效果调试
    if (prEntry) {
        prEntry->read_proc = CAMERA_HW_DumpReg_To_Proc;
        prEntry->write_proc = CAMERA_HW_Reg_Debug;
    }
    else {
        PK_ERR("add /proc/driver/camsensor entry fail \n");
    }

    //Register proc file for sub sensor register debug
    prEntry = create_proc_entry("driver/camsensor2", 0, NULL); //在proc下创建driver/camsensor2这个节点,用于后置摄像头进行adb效果调试
    if (prEntry) {
        prEntry->read_proc = CAMERA_HW_DumpReg_To_Proc;
        prEntry->write_proc = CAMERA_HW_Reg_Debug2;
    }
    else {
        PK_ERR("add /proc/driver/camsensor2 entry fail \n");
    }
    atomic_set(&g_CamHWOpend, 0);
    //atomic_set(&g_CamHWOpend2, 0);
    atomic_set(&g_CamDrvOpenCnt, 0);
    //atomic_set(&g_CamDrvOpenCnt2, 0);
    atomic_set(&g_CamHWOpening, 0);
    return 0;
}
        CAMERA_HW_i2C_init函数主要做的是对I2C总线的版级文件进行了填充,然后注册platform总线的driver,通过g_stCAMERA_HW_Driver结构体里面的name来与device进行匹配。同时,在函数里面还在proc目录下创建了driver/camsensor和driver/camsensor2两个节点,这样做主要是方便sensor的IC原厂FAE利用adb进行效果调试的。
static 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,
    }
};
      g_stCAMERA_HW_Driver结构体中主要有probe、remove、suspend等接口的实现,probe接口为设备注册的匹配函数,所以在在注册了driver就会调用 .probe          = CAMERA_HW_probe进入CAMERA_HW_probe函数:
static int CAMERA_HW_probe(struct platform_device *pdev)
{
    return i2c_add_driver(&CAMERA_HW_i2c_driver);
}
struct i2c_driver CAMERA_HW_i2c_driver = {
    .probe = CAMERA_HW_i2c_probe,
    .remove = CAMERA_HW_i2c_remove,
    .driver.name = CAMERA_HW_DRVNAME1,
    .id_table = CAMERA_HW_i2c_id,
};
       CAMERA_HW_probe做的就是注册一个i2c的driver,camera会挂载在I2C总线上,利用I2C进入寄存器的读写,所以,sensor驱动最终还是会注册I2C设备,I2C总线的注册其实跟platform总线的注册大致相同,注册完I2C driver后系统就会调用CAMERA_HW_i2c_driver 结构体里面的 .probe = CAMERA_HW_i2c_probe:
static int CAMERA_HW_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    int i4RetValue = 0;
    PK_DBG("[CAMERA_HW] Attach I2C \n");

    //get sensor i2c client
    spin_lock(&kdsensor_drv_lock);
    g_pstI2Cclient = client;   //这里是获得我们的clientdevice,并且以platform方式进行注册
    //set I2C clock rate
    g_pstI2Cclient->timing = 300;//200k
    spin_unlock(&kdsensor_drv_lock);

    //Register char driver
    i4RetValue = RegisterCAMERA_HWCharDrv(); // 注册字符驱动

    if(i4RetValue){
        PK_ERR("[CAMERA_HW] register char device failed!\n");
        return i4RetValue;
    }

    //spin_lock_init(&g_CamHWLock);

    PK_DBG("[CAMERA_HW] Attached!! \n");
    return 0;
}
      在CAMERA_HW_i2c_probe函数里面主要就是调用了RegisterCAMERA_HWCharDrv函数来注册一个字符驱动。
inline static int RegisterCAMERA_HWCharDrv(void)
{
    struct device* sensor_device = NULL;

#if CAMERA_HW_DYNAMIC_ALLOCATE_DEVNO
    if( alloc_chrdev_region(&g_CAMERA_HWdevno, 0, 1,CAMERA_HW_DRVNAME1) ) // 动态分配一个字符设备
    {
        PK_DBG("[CAMERA SENSOR] Allocate device no failed\n");

        return -EAGAIN;
    }
#else
    if( register_chrdev_region(  g_CAMERA_HWdevno , 1 , CAMERA_HW_DRVNAME1) ) // 静态分配一个字符设备
    {
        PK_DBG("[CAMERA SENSOR] Register device no failed\n");

        return -EAGAIN;
    }
#endif

    //Allocate driver
    g_pCAMERA_HW_CharDrv = cdev_alloc();  // 申请一个cdev结构体

    if(NULL == g_pCAMERA_HW_CharDrv)
    {
        unregister_chrdev_region(g_CAMERA_HWdevno, 1);

        PK_DBG("[CAMERA SENSOR] Allocate mem for kobject failed\n");

        return -ENOMEM;
    }

    //Attatch file operation.
    cdev_init(g_pCAMERA_HW_CharDrv, &g_stCAMERA_HW_fops); //关联到file_operation进入字符设备

    g_pCAMERA_HW_CharDrv->owner = THIS_MODULE;

    //Add to system
    if(cdev_add(g_pCAMERA_HW_CharDrv, g_CAMERA_HWdevno, 1)) //将我们分配的字符设备,attach上file_operation添加到system
    {
        PK_DBG("[mt6516_IDP] Attatch file operation failed\n");

        unregister_chrdev_region(g_CAMERA_HWdevno, 1);

        return -EAGAIN;
    }

    sensor_class = class_create(THIS_MODULE, "sensordrv");  //创建一个sensordrv类
    if (IS_ERR(sensor_class)) {
        int ret = PTR_ERR(sensor_class);
        PK_DBG("Unable to create class, err = %d\n", ret);
        return ret;
    }
    sensor_device = device_create(sensor_class, NULL, g_CAMERA_HWdevno, NULL, CAMERA_HW_DRVNAME1);

    return 0;
}
        linux驱动分为三大部分驱动,分别为字符驱动,块驱动以及网络驱动,而camera的模块驱动为字符驱动,所以RegisterCAMERA_HWCharDrv函数主要是对camera_image进行字符驱动注册,代码开始先判断是否定义了CAMERA_HW_DYNAMIC_ALLOCATE_DEVNO变量来判断动态还是静态分配一个字符设备,然后通过cdev_alloc申请了一个cdev结构体后,通过cdev_init将g_stCAMERA_HW_fops关联到字符设备,这是这个函数往下走下去的关键。然后就是将我们分配的字符设备,attach上file_operation添加到sys,最后在sys/class目录下创建一个sensordrv类,如下图所示:
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       下面来看看g_stCAMERA_HW_fops结构体里面的内容:
static const struct file_operations g_stCAMERA_HW_fops =
{
    .owner = THIS_MODULE,
    .open = CAMERA_HW_Open,
    .release = CAMERA_HW_Release,
    .unlocked_ioctl = CAMERA_HW_Ioctl

};
      file_operations 是为上层调用底层提供的接口,往往打开接口就是先打开open,那么先来看看struct file_operations g_stCAMERA_HW_fops结构体中的open函数;
static int CAMERA_HW_Open(struct inode * a_pstInode, struct file * a_pstFile)
{
    //reset once in multi-open
    if ( atomic_read(&g_CamDrvOpenCnt) == 0) {
         //default OFF state
         //MUST have
         //kdCISModulePowerOn(DUAL_CAMERA_MAIN_SENSOR,"",true,CAMERA_HW_DRVNAME1);
         //kdCISModulePowerOn(DUAL_CAMERA_SUB_SENSOR,"",true,CAMERA_HW_DRVNAME1);
         //kdCISModulePowerOn(DUAL_CAMERA_MAIN_2_SENSOR,"",true,CAMERA_HW_DRVNAME1);
         
         //kdCISModulePowerOn(DUAL_CAMERA_MAIN_SENSOR,"",false,CAMERA_HW_DRVNAME1);
         //kdCISModulePowerOn(DUAL_CAMERA_SUB_SENSOR,"",false,CAMERA_HW_DRVNAME1);
         //kdCISModulePowerOn(DUAL_CAMERA_MAIN_2_SENSOR,"",false,CAMERA_HW_DRVNAME1);
    }

    //
    atomic_inc(&g_CamDrvOpenCnt);
    return 0;
}
       整个函数就是对g_CamDrvOpenCnt变量进行了一个原子读的过程,没有进行别的操作。而上层跟驱动进行通讯主要是通过ioctl发送命令,然后进行数据传输,然后在看看.unlocked_ioctl= CAMERA_HW_Ioctl中的CAMERA_HW_Ioctl操作;
static long CAMERA_HW_Ioctl(
    struct file * a_pstFile,
    unsigned int a_u4Command,
    unsigned long a_u4Param
)
{
    int i4RetValue = 0;
    void * pBuff = NULL;
    u32 *pIdx = NULL;

    mutex_lock(&kdCam_Mutex);

    if(_IOC_NONE == _IOC_DIR(a_u4Command)) {
    }
    else {
        pBuff = kmalloc(_IOC_SIZE(a_u4Command),GFP_KERNEL); //申请分配一个buffer

        if(NULL == pBuff) {
            PK_DBG("[CAMERA SENSOR] ioctl allocate mem failed\n");
            i4RetValue = -ENOMEM;
            goto CAMERA_HW_Ioctl_EXIT;
        }

        if(_IOC_WRITE & _IOC_DIR(a_u4Command)){ //判断是否可写
                //将用户传递过来的命令参数复制到内核空间,接下来我们会根据这个数据进行选择
            if(copy_from_user(pBuff , (void *) a_u4Param, _IOC_SIZE(a_u4Command))) {
                kfree(pBuff);
                PK_DBG("[CAMERA SENSOR] ioctl copy from user failed\n");
                i4RetValue =  -EFAULT;
                goto CAMERA_HW_Ioctl_EXIT;
            }
        }
    }

    pIdx = (u32*)pBuff;
    switch(a_u4Command) {
#if 0
        case KDIMGSENSORIOC_X_POWER_ON:
            i4RetValue = kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM) *pIdx, true, CAMERA_HW_DRVNAME);
            break;
        case KDIMGSENSORIOC_X_POWER_OFF:
            i4RetValue = kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM) *pIdx, false, CAMERA_HW_DRVNAME);
            break;
#endif
        case KDIMGSENSORIOC_X_SET_DRIVER:
            i4RetValue = kdSetDriver((unsigned int*)pBuff);
            break;
        case KDIMGSENSORIOC_T_OPEN:
            i4RetValue = adopt_CAMERA_HW_Open();
            break;
        case KDIMGSENSORIOC_X_GETINFO:
            i4RetValue = adopt_CAMERA_HW_GetInfo(pBuff);
            break;
        case KDIMGSENSORIOC_X_GETRESOLUTION:
            i4RetValue = adopt_CAMERA_HW_GetResolution(pBuff);
            break;
        case KDIMGSENSORIOC_X_FEATURECONCTROL:
            i4RetValue = adopt_CAMERA_HW_FeatureControl(pBuff);
            break;
        case KDIMGSENSORIOC_X_CONTROL:
            i4RetValue = adopt_CAMERA_HW_Control(pBuff);
            break;
        case KDIMGSENSORIOC_T_CLOSE:
            i4RetValue = adopt_CAMERA_HW_Close();
            break;
        case KDIMGSENSORIOC_T_CHECK_IS_ALIVE:
            i4RetValue = adopt_CAMERA_HW_CheckIsAlive();
            break;
        case KDIMGSENSORIOC_X_GET_SOCKET_POS:
            i4RetValue = kdGetSocketPostion((unsigned int*)pBuff);
            break;
        case KDIMGSENSORIOC_X_SET_I2CBUS:
            //i4RetValue = kdSetI2CBusNum(*pIdx);
            break;
        case KDIMGSENSORIOC_X_RELEASE_I2C_TRIGGER_LOCK:
            //i4RetValue = kdReleaseI2CTriggerLock();
            break;
         default :
              PK_DBG("No such command \n");
              i4RetValue = -EPERM;
              break;

    }

    if(_IOC_READ & _IOC_DIR(a_u4Command)) {
        if(copy_to_user((void __user *) a_u4Param , pBuff , _IOC_SIZE(a_u4Command))) {
            kfree(pBuff);
            PK_DBG("[CAMERA SENSOR] ioctl copy to user failed\n");
            i4RetValue =  -EFAULT;
            goto CAMERA_HW_Ioctl_EXIT;
        }
    }

    kfree(pBuff);
CAMERA_HW_Ioctl_EXIT:
    mutex_unlock(&kdCam_Mutex);
    return i4RetValue;
}
    ioctl主要就是上层通过cmd命令来与底层进行通信,下面就看看这个比较重要的cmd命令:
    a):KDIMGSENSORIOC_T_OPEN命令:
 case KDIMGSENSORIOC_T_OPEN:
            i4RetValue = adopt_CAMERA_HW_Open();
            break;

inline static int adopt_CAMERA_HW_Open(void)
{
        UINT32 err = 0;

        KD_IMGSENSOR_PROFILE_INIT();
        if (atomic_read(&g_CamHWOpend) == 0  ) {
             if (g_pSensorFunc) { //判断我们imagesensor 操作函数指针是否为NULL,如果为NULL,报错,因为我们就是靠这个操作函数集合去操作imagesensor 的
                  err = g_pSensorFunc->SensorOpen(); // 会调用到kd_MultiSensorFunc里面的kd_MultiSensorOpen函数
                  if(ERROR_NONE != err) {
                        PK_DBG(" ERROR:SensorOpen(), turn off power \n");
                        kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM*) g_invokeSocketIdx, g_invokeSensorNameStr, false, CAMERA_HW_DRVNAME1);
                  }
           }
        else {
            PK_DBG(" ERROR:NULL g_pSensorFunc\n");
        }
        KD_IMGSENSOR_PROFILE("SensorOpen");
    }
    else {
        //PK_ERR("adopt_CAMERA_HW_Open Fail, g_CamHWOpend = %d,g_CamHWOpend2 = %d\n ",atomic_read(&g_CamHWOpend),atomic_read(&g_CamHWOpend2) );
     PK_ERR("adopt_CAMERA_HW_Open Fail, g_CamHWOpend = %d\n ",atomic_read(&g_CamHWOpend) );
    }

    if (err == 0 ) {
        atomic_set(&g_CamHWOpend, 1);
        //atomic_set(&g_CamHWOpend2, 1);
    }

    return err?-EIO:err;
}     /* adopt_CAMERA_HW_Open() */
        g_pSensorFunc结构体的定义为staticMULTI_SENSOR_FUNCTION_STRUCT *g_pSensorFunc = &kd_MultiSensorFunc,它跟kd_MultiSensorFunc指向相同的地址,if (g_pSensorFunc) 由这里可以看出,上层调用ioctl命令时不可能先走KDIMGSENSORIOC_T_OPEN这个命令,因为此时g_pSensorFunc 为NULL,还没有赋值,由后面的代码可以看到,ioctl先走的cmd命令是KDIMGSENSORIOC_X_SET_DRIVER。当g_pSensorFunc不为NULL时,就是执行这个err =g_pSensorFunc->SensorOpen(); ,这里的SensorOpen函数指向的是kd_MultiSensorOpen函数。
MUINT32 kd_MultiSensorOpen ( void )
{
MUINT32 ret = ERROR_NONE;
MINT32 i = 0;
    KD_MULTI_FUNCTION_ENTRY(); // 得到当前时间
    for ( i = (KDIMGSENSOR_MAX_INVOKE_DRIVERS-1) ; i >= KDIMGSENSOR_INVOKE_DRIVER_0 ; i-- ) {
        if ( g_bEnableDriver[i] && g_pInvokeSensorFunc[i] ) {
            // turn on power
            ret = kdCISModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM)g_invokeSocketIdx[i],(char*)g_invokeSensorNameStr[i],true,CAMERA_HW_DRVNAME1);
            if ( ERROR_NONE != ret ) {  // 上电
                PK_ERR("[%s]",__FUNCTION__);
                return ret;
            }
            //wait for power stable
            mDELAY(10);
            KD_IMGSENSOR_PROFILE("kdModulePowerOn");
            ret = g_pInvokeSensorFunc[i]->SensorOpen(); //调用到模块驱动中的open函数,g_pInvokeSensorFunc保存的值为模块驱动中的SENSOR_FUNCTION_STRUCT     SensorFuncGC2035这个结构体
            if ( ERROR_NONE != ret ) {
                    kdCISModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM)g_invokeSocketIdx[i],(char*)g_invokeSensorNameStr[i],false,CAMERA_HW_DRVNAME1); // 掉电
                PK_ERR("SensorOpen");
                return ret;
            }
        }
    }
    KD_MULTI_FUNCTION_EXIT();
    return ERROR_NONE;
}
       g_bEnableDriver定义为一个bool型的变量,定义如下static BOOL g_bEnableDriver[KDIMGSENSOR_MAX_INVOKE_DRIVERS] ={FALSE,FALSE},而g_pInvokeSensorFunc的定义为static SENSOR_FUNCTION_STRUCT*g_pInvokeSensorFunc[KDIMGSENSOR_MAX_INVOKE_DRIVERS] = {NULL,NULL};而g_pInvokeSensorFunc的地址跟模块驱动中的SENSOR_FUNCTION_STRUCT     SensorFuncGC2035这个地址指向是相同的,他是作为一个参数传递来被调用的,这两个变量的实现都会在后面KDIMGSENSORIOC_X_SET_DRIVER命令调用时介绍的。当这两个变量都为true时,就对sensor进行上电,然后就通过ret =g_pInvokeSensorFunc[i]->SensorOpen()进入到了模块sensor驱动中的open函数。至于上电跟掉电函数kdCISModulePowerOn,在mediatek/custom/ztenj72_we_72_m536_kk/kernel/camera/camera/kd_camera_hw.c文件中,其实上电跟掉电时序就是配置一些GPIO口,然后在把camera的三路电压按dateshell配置一下上掉电的时间。
     b):KDIMGSENSORIOC_X_SET_DRIVER命令:
case KDIMGSENSORIOC_X_SET_DRIVER:
            i4RetValue = kdSetDriver((unsigned int*)pBuff);
            break;
int kdSetDriver(unsigned int* pDrvIndex)
{
    ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT *pSensorList = NULL; // 这是一个保存cameraId跟cameraName的结构体
    u32 drvIdx[KDIMGSENSOR_MAX_INVOKE_DRIVERS] = {0,0};
    u32 i;

    PK_XLOG_INFO("pDrvIndex:0x%08x/0x%08x \n",pDrvIndex[KDIMGSENSOR_INVOKE_DRIVER_0],pDrvIndex[KDIMGSENSOR_INVOKE_DRIVER_1]);
    //set driver for MAIN or SUB sensor

    if (0 != kdGetSensorInitFuncList(&pSensorList)) //调用这个函数,取得所有添加的sensor的结构的首地址
    {
        PK_ERR("ERROR:kdGetSensorInitFuncList()\n");
        return -EIO;
    }

    for ( i = KDIMGSENSOR_INVOKE_DRIVER_0; i < KDIMGSENSOR_MAX_INVOKE_DRIVERS ; i++ ) {
        //
        spin_lock(&kdsensor_drv_lock);
        g_bEnableDriver[i] = FALSE;
        g_invokeSocketIdx[i] = (CAMERA_DUAL_CAMERA_SENSOR_ENUM)((pDrvIndex[i] & KDIMGSENSOR_DUAL_MASK_MSB)>>KDIMGSENSOR_DUAL_SHIFT); // 保存camera的sensorId
          spin_unlock(&kdsensor_drv_lock);
        drvIdx[i] = (pDrvIndex[i] & KDIMGSENSOR_DUAL_MASK_LSB);
        //
        if ( DUAL_CAMERA_NONE_SENSOR == g_invokeSocketIdx[i] ) { continue; }
          //ToDo: remove print information
          PK_XLOG_INFO("[kdSetDriver] i,g_invokeSocketIdx[%d] = %d :\n",i,i,drvIdx[i]);
          PK_XLOG_INFO("[kdSetDriver] i,drvIdx[%d] = %d :\n",i,i,drvIdx[i]);
        //
        if ( MAX_NUM_OF_SUPPORT_SENSOR > drvIdx[i] ) {
            if (NULL == pSensorList[drvIdx[i]].SensorInit) {
                 PK_ERR("ERROR:kdSetDriver()\n");
                 return -EIO;
             }

            pSensorList[drvIdx[i]].SensorInit(&g_pInvokeSensorFunc[i]);// 调用模块驱动中的init函数,将模块驱动里面的SENSOR_FUNCTION_STRUCT  SensorFuncOV2685值传递给g_pInvokeSensorFunc结构体
            if (NULL == g_pInvokeSensorFunc[i]) {
                PK_ERR("ERROR:NULL g_pSensorFunc[%d]\n",i);
            return -EIO;
             }
            //
            spin_lock(&kdsensor_drv_lock);
            g_bEnableDriver[i] = TRUE;
            g_CurrentInvokeCam = g_invokeSocketIdx[i];              
            spin_unlock(&kdsensor_drv_lock);
             //get sensor name
            memcpy((char*)g_invokeSensorNameStr[i],(char*)pSensorList[drvIdx[i]].drvname,sizeof(pSensorList[drvIdx[i]].drvname));
            //return sensor ID
            //pDrvIndex[0] = (unsigned int)pSensorList[drvIdx].SensorId;
            PK_XLOG_INFO("[kdSetDriver] :[%d][%d][%d][%s][%d]\n",i,g_bEnableDriver[i],g_invokeSocketIdx[i],g_invokeSensorNameStr[i],sizeof(pSensorList[drvIdx[i]].drvname));
        }
    }
    return 0;
}
        kdSetDriver这个函数比较重要,上层调用底层的命令应该第一步就是调用这个命令的,函数开头定义了一个ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT *pSensorList = NULL;这样的结构体,ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT 变量是为src/kd_sensorlist.h文件里面保存sensor的ID,NAME以及init的结构体,if (0 !=kdGetSensorInitFuncList(&pSensorList))通过调用kdGetSensorInitFuncList函数,将pSensorList的首地址指向src/kd_sensorlist.h里面ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT变量的首地址。
UINT32 kdGetSensorInitFuncList(ACDK_KD_SENSOR_INIT_FUNCTION_STRUCT **ppSensorList)
{
     if (NULL == ppSensorList)
     {
          PK_DBG("[kdGetSensorInitFuncList]ERROR: NULL ppSensorList\n");
          return 1;
     }
     *ppSensorList = &kdSensorList[0]; // kdSensorList在kd_sensorlist.h文件里面,就是保存cameraId,cameraNmae,模块驱动人口函数的结构体
     return 0;
}
      调用了kdGetSensorInitFuncList后,代码先将g_bEnableDriver置为FALSE,而这个变量就是在上面的open函数里面出现过的。然后通过if (NULL ==pSensorList[drvIdx[i]].SensorInit)判断模块驱动的init函数是否为NULL,pSensorList[drvIdx[i]].SensorInit(&g_pInvokeSensorFunc[i]);传递&g_pInvokeSensorFunc[i]为参数,其中还是传递的地址,这就将g_pInvokeSensorFunc的首地址指向了模块驱动函数中的UINT32 GC2035_YUV_SensorInit(PSENSOR_FUNCTION_STRUCT *pfFunc)这个函数,这就是上面kd_MultiSensorOpen 中为什么g_pInvokeSensorFunc可以直接调用模块驱动中的open函数,其实就是在这里实现的。当调用完成后,然后就将camera的ID,NAME等信息保存并将g_bEnableDriver[i]变量置为TRUE。
     而ioctl里面的其他几条cmd命令基本都是在获取到了g_pInvokeSensorFunc后然后调用模块驱动中的各个接口函数,例如:
case KDIMGSENSORIOC_T_OPEN:
            i4RetValue = adopt_CAMERA_HW_Open();
            break;
inline static int adopt_CAMERA_HW_Open(void)
{
    UINT32 err = 0;

        KD_IMGSENSOR_PROFILE_INIT();
        //power on sensor
    //if ((atomic_read(&g_CamHWOpend) == 0) && (atomic_read(&g_CamHWOpend2) == 0)) { 
    if (atomic_read(&g_CamHWOpend) == 0  ) {
        //move into SensorOpen() for 2on1 driver
        // turn on power
        //kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM*) g_invokeSocketIdx, g_invokeSensorNameStr,true, CAMERA_HW_DRVNAME);
        //wait for power stable
        //mDELAY(10);
        //KD_IMGSENSOR_PROFILE("kdModulePowerOn");
        //
        if (g_pSensorFunc) {
            err = g_pSensorFunc->SensorOpen();
            if(ERROR_NONE != err) {
                PK_DBG(" ERROR:SensorOpen(), turn off power \n");
                kdModulePowerOn((CAMERA_DUAL_CAMERA_SENSOR_ENUM*) g_invokeSocketIdx, g_invokeSensorNameStr, false, CAMERA_HW_DRVNAME1);
            }
        }
        else {
            PK_DBG(" ERROR:NULL g_pSensorFunc\n");
        }
        KD_IMGSENSOR_PROFILE("SensorOpen");
    }
    else {
        //PK_ERR("adopt_CAMERA_HW_Open Fail, g_CamHWOpend = %d,g_CamHWOpend2 = %d\n ",atomic_read(&g_CamHWOpend),atomic_read(&g_CamHWOpend2) );
	PK_ERR("adopt_CAMERA_HW_Open Fail, g_CamHWOpend = %d\n ",atomic_read(&g_CamHWOpend) );
    }

    if (err == 0 ) {
        atomic_set(&g_CamHWOpend, 1);
        //atomic_set(&g_CamHWOpend2, 1);
    }

    return err?-EIO:err;
}	/* adopt_CAMERA_HW_Open() */
     KDIMGSENSORIOC_T_OPEN命令就是通过调用adopt_CAMERA_HW_Open函数,而adopt_CAMERA_HW_Open函数中会通过err =g_pSensorFunc->SensorOpen();调用到模块驱动中的open函数。而在这里就不一一介绍了,下面来看看你看驱动中的各个接口函数有什么含义,以gc2035驱动为模板分析。
UINT32 GC2035_YUV_SensorInit(PSENSOR_FUNCTION_STRUCT *pfFunc)
{
     /* To Do : Check Sensor status here */
     if (pfFunc!=NULL)
          *pfFunc=&SensorFuncGC2035;

     return ERROR_NONE;
}     /* Sensor

SENSOR_FUNCTION_STRUCT     SensorFuncGC2035=
{
     GC2035Open,
     GC2035GetInfo,
     GC2035GetResolution,
     GC2035FeatureControl,
     GC2035Control,
     GC2035Close
};
GC2035Open:
UINT32 GC2035Open(void)
{
     volatile signed char i;
     kal_uint16 sensor_id=0;

     zoom_factor = 0;
     Sleep(10);
     SENSORDB("GC2035Open\r\n");


     //  Read sensor ID to adjust I2C is OK?
     for(i=0;i<3;i++)
     {
          sensor_id = (GC2035_read_cmos_sensor(0xf0) << 8) | GC2035_read_cmos_sensor(0xf1);
          if(sensor_id != GC2035_SENSOR_ID)  // GC2035_SENSOR_ID = 0x2035
          {
               return ERROR_SENSOR_CONNECT_FAIL;
          }
     }
    
     SENSORDB("GC2035 Sensor Read ID OK \r\n");
     GC2035_Sensor_Init();
     GC2035_Write_More();
     Preview_Shutter =GC2035_read_shutter();

     return ERROR_NONE;
}    
   通过函数实现就可以看出来,这里是在通过i2c控制imagesensor 的register,读取deivceid ,看是否链接上对应的imagesensor;
GC2035GetInfo:
UINT32 GC2035GetInfo(MSDK_SCENARIO_ID_ENUM ScenarioId,
                           MSDK_SENSOR_INFO_STRUCT *pSensorInfo,
                           MSDK_SENSOR_CONFIG_STRUCT *pSensorConfigData)
{
     pSensorInfo->SensorPreviewResolutionX=GC2035_IMAGE_SENSOR_PV_WIDTH;
     pSensorInfo->SensorPreviewResolutionY=GC2035_IMAGE_SENSOR_PV_HEIGHT;
     pSensorInfo->SensorFullResolutionX=GC2035_IMAGE_SENSOR_FULL_WIDTH;
     pSensorInfo->SensorFullResolutionY=GC2035_IMAGE_SENSOR_FULL_HEIGHT;

     pSensorInfo->SensorCameraPreviewFrameRate=30;
     pSensorInfo->SensorVideoFrameRate=30;
     pSensorInfo->SensorStillCaptureFrameRate=10;
     pSensorInfo->SensorWebCamCaptureFrameRate=15;
     pSensorInfo->SensorResetActiveHigh=FALSE;
     pSensorInfo->SensorResetDelayCount=1;
     pSensorInfo->SensorOutputDataFormat=SENSOR_OUTPUT_FORMAT_YUYV;
     pSensorInfo->SensorClockPolarity=SENSOR_CLOCK_POLARITY_LOW;     /*??? */
     pSensorInfo->SensorClockFallingPolarity=SENSOR_CLOCK_POLARITY_LOW;
     pSensorInfo->SensorHsyncPolarity = SENSOR_CLOCK_POLARITY_LOW;
     pSensorInfo->SensorVsyncPolarity = SENSOR_CLOCK_POLARITY_LOW;
     pSensorInfo->SensorInterruptDelayLines = 1;
     pSensorInfo->CaptureDelayFrame = 4;
     pSensorInfo->PreviewDelayFrame = 1; // 2 betty
     pSensorInfo->VideoDelayFrame = 0;
     pSensorInfo->SensorMasterClockSwitch = 0;
     pSensorInfo->SensorDrivingCurrent = ISP_DRIVING_6MA;
     pSensorInfo->SensroInterfaceType=SENSOR_INTERFACE_TYPE_PARALLEL;
    
     SENSORDB("GC2035GetInfo\r\n");
    

     switch (ScenarioId)
     {
          case MSDK_SCENARIO_ID_CAMERA_PREVIEW:
          case MSDK_SCENARIO_ID_VIDEO_PREVIEW:
               pSensorInfo->SensorClockFreq=22;
               pSensorInfo->SensorClockDividCount=3;
               pSensorInfo->SensorClockRisingCount= 0;
               pSensorInfo->SensorClockFallingCount= 2;
               pSensorInfo->SensorPixelClockCount= 3;
               pSensorInfo->SensorDataLatchCount= 2;
                     pSensorInfo->SensorGrabStartX = 2;
                     pSensorInfo->SensorGrabStartY = 2;
    
          break;
          case MSDK_SCENARIO_ID_CAMERA_CAPTURE_JPEG:
               pSensorInfo->SensorClockFreq=22;
               pSensorInfo->SensorClockDividCount=3;
               pSensorInfo->SensorClockRisingCount= 0;
               pSensorInfo->SensorClockFallingCount= 2;
               pSensorInfo->SensorPixelClockCount= 3;
               pSensorInfo->SensorDataLatchCount= 2;
                     pSensorInfo->SensorGrabStartX = 2;
                     pSensorInfo->SensorGrabStartY = 2;              
          break;
          default:
               pSensorInfo->SensorClockFreq=22;
               pSensorInfo->SensorClockDividCount=3;
               pSensorInfo->SensorClockRisingCount=0;
               pSensorInfo->SensorClockFallingCount=2;
               pSensorInfo->SensorPixelClockCount=3;
               pSensorInfo->SensorDataLatchCount=2;
                     pSensorInfo->SensorGrabStartX = 2;  
                     pSensorInfo->SensorGrabStartY = 2;            
              
          break;
     }
     memcpy(pSensorConfigData, &GC2035SensorConfigData, sizeof(MSDK_SENSOR_CONFIG_STRUCT));
     return ERROR_NONE;
}
     上面的函数一共传递进来了3个变量,第一个变量:是控制camera的工作模式,(拍照、摄像等等)第2个参数:主要设置imagesensor 的频率的(时钟频率、预览频率、以及同步频率);第3个参数同样也是camera的设置,其实要看到底是在干嘛,只要看看这个参数是如何定义的就可以了。
GC2035GetResolution:
UINT32 GC2035GetResolution(MSDK_SENSOR_RESOLUTION_INFO_STRUCT *pSensorResolution)
{
     SENSORDB("GC2035GetResolution\r\n");

     pSensorResolution->SensorFullWidth=GC2035_IMAGE_SENSOR_FULL_WIDTH - 2 * IMAGE_SENSOR_START_GRAB_X;
     pSensorResolution->SensorFullHeight=GC2035_IMAGE_SENSOR_FULL_HEIGHT - 2 * IMAGE_SENSOR_START_GRAB_Y;
     pSensorResolution->SensorPreviewWidth=GC2035_IMAGE_SENSOR_PV_WIDTH - 2 * IMAGE_SENSOR_START_GRAB_X;
     pSensorResolution->SensorPreviewHeight=GC2035_IMAGE_SENSOR_PV_HEIGHT - 2 * IMAGE_SENSOR_START_GRAB_Y;
     pSensorResolution->SensorVideoWidth=GC2035_IMAGE_SENSOR_PV_WIDTH - 2 * IMAGE_SENSOR_START_GRAB_X;
     pSensorResolution->SensorVideoHeight=GC2035_IMAGE_SENSOR_PV_HEIGHT - 2 * IMAGE_SENSOR_START_GRAB_Y;

     return ERROR_NONE;
}
      设置camera在预览模式下的高度、宽度等;
GC2035FeatureControl:
UINT32 GC2035FeatureControl(MSDK_SENSOR_FEATURE_ENUM FeatureId,
                                   UINT8 *pFeaturePara,UINT32 *pFeatureParaLen)
{
     UINT16 *pFeatureReturnPara16=(UINT16 *) pFeaturePara;
     UINT16 *pFeatureData16=(UINT16 *) pFeaturePara;
     UINT32 *pFeatureReturnPara32=(UINT32 *) pFeaturePara;
     UINT32 *pFeatureData32=(UINT32 *) pFeaturePara;
     MSDK_SENSOR_CONFIG_STRUCT *pSensorConfigData=(MSDK_SENSOR_CONFIG_STRUCT *) pFeaturePara;
     MSDK_SENSOR_REG_INFO_STRUCT *pSensorRegData=(MSDK_SENSOR_REG_INFO_STRUCT *) pFeaturePara;

     switch (FeatureId)
     {
          case SENSOR_FEATURE_GET_RESOLUTION:
               *pFeatureReturnPara16++=GC2035_IMAGE_SENSOR_FULL_WIDTH;
               *pFeatureReturnPara16=GC2035_IMAGE_SENSOR_FULL_HEIGHT;
               *pFeatureParaLen=4;
          break;
          case SENSOR_FEATURE_GET_PERIOD:
               *pFeatureReturnPara16++=GC2035_IMAGE_SENSOR_PV_WIDTH;
               *pFeatureReturnPara16=GC2035_IMAGE_SENSOR_PV_HEIGHT;
               *pFeatureParaLen=4;
          break;
          case SENSOR_FEATURE_GET_PIXEL_CLOCK_FREQ:
               //*pFeatureReturnPara32 = GC2035_sensor_pclk/10;
               *pFeatureParaLen=4;
          break;
          case SENSOR_FEATURE_SET_ESHUTTER:
          break;
          case SENSOR_FEATURE_SET_NIGHTMODE:
               GC2035_night_mode((BOOL) *pFeatureData16);
          break;
          case SENSOR_FEATURE_SET_GAIN:
          case SENSOR_FEATURE_SET_FLASHLIGHT:
          break;
          case SENSOR_FEATURE_SET_ISP_MASTER_CLOCK_FREQ:
               GC2035_isp_master_clock=*pFeatureData32;
          break;
          case SENSOR_FEATURE_SET_REGISTER:
               GC2035_write_cmos_sensor(pSensorRegData->RegAddr, pSensorRegData->RegData);
          break;
          case SENSOR_FEATURE_GET_REGISTER:
               pSensorRegData->RegData = GC2035_read_cmos_sensor(pSensorRegData->RegAddr);
          break;
          case SENSOR_FEATURE_GET_CONFIG_PARA:
               memcpy(pSensorConfigData, &GC2035SensorConfigData, sizeof(MSDK_SENSOR_CONFIG_STRUCT));
               *pFeatureParaLen=sizeof(MSDK_SENSOR_CONFIG_STRUCT);
          break;
          case SENSOR_FEATURE_SET_CCT_REGISTER:
          case SENSOR_FEATURE_GET_CCT_REGISTER:
          case SENSOR_FEATURE_SET_ENG_REGISTER:
          case SENSOR_FEATURE_GET_ENG_REGISTER:
          case SENSOR_FEATURE_GET_REGISTER_DEFAULT:

          case SENSOR_FEATURE_CAMERA_PARA_TO_SENSOR:
          case SENSOR_FEATURE_SENSOR_TO_CAMERA_PARA:
          case SENSOR_FEATURE_GET_GROUP_INFO:
          case SENSOR_FEATURE_GET_ITEM_INFO:
          case SENSOR_FEATURE_SET_ITEM_INFO:
          case SENSOR_FEATURE_GET_ENG_INFO:
          break;
          case SENSOR_FEATURE_GET_GROUP_COUNT:
                        *pFeatureReturnPara32++=0;
                        *pFeatureParaLen=4;        
              break;
          case SENSOR_FEATURE_GET_LENS_DRIVER_ID:
               // get the lens driver ID from EEPROM or just return LENS_DRIVER_ID_DO_NOT_CARE
               // if EEPROM does not exist in camera module.
               *pFeatureReturnPara32=LENS_DRIVER_ID_DO_NOT_CARE;
               *pFeatureParaLen=4;
          break;
          case SENSOR_FEATURE_CHECK_SENSOR_ID:
               GC2035_GetSensorID(pFeatureData32);
               break;
          case SENSOR_FEATURE_SET_YUV_CMD:
                 //printk("GC2035 YUV sensor Setting:%d, %d \n", *pFeatureData32,  *(pFeatureData32+1));
               GC2035YUVSensorSetting((FEATURE_ID)*pFeatureData32, *(pFeatureData32+1));
          break;
          case SENSOR_FEATURE_SET_VIDEO_MODE:
                 GC2035YUVSetVideoMode(*pFeatureData16);
                 break;
          default:
               break;              
     }
     return ERROR_NONE;
}
      这个是上层会提供featureid,底层通过这个id进行不同case的执行为para和paralen赋值:
GC2035Control:
UINT32 GC2035Control(MSDK_SCENARIO_ID_ENUM ScenarioId, MSDK_SENSOR_EXPOSURE_WINDOW_STRUCT *pImageWindow,
                           MSDK_SENSOR_CONFIG_STRUCT *pSensorConfigData)
{
     switch (ScenarioId)
     {
          case MSDK_SCENARIO_ID_CAMERA_PREVIEW:
          case MSDK_SCENARIO_ID_VIDEO_PREVIEW:
                    GC2035_sensor_cap_zsd = KAL_FALSE;
               GC2035Preview(pImageWindow, pSensorConfigData);
          break;
          case MSDK_SCENARIO_ID_CAMERA_CAPTURE_JPEG:
               GC2035_sensor_cap_zsd = KAL_FALSE;
               GC2035Capture(pImageWindow, pSensorConfigData);
          break;
          case MSDK_SCENARIO_ID_CAMERA_ZSD:
               GC2035_sensor_cap_zsd = KAL_TRUE;
               GC2035Capture(pImageWindow, pSensorConfigData);
          break;
          default:
              break;
     }
     return TRUE;
}
    这个函数和上面一样,也是提供控制的一个Interface。

    GC2035Close:

UINT32 GC2035Close(void)
{
//     CISModulePowerOn(FALSE);
     SENSORDB("GC2035Close\r\n");

     return ERROR_NONE;
}
     这里close没有实现任何事情。
     到这来MTK的camera驱动的加载就结束了,但这只是在整个android中对camera架构中最基础的一些分析,android系统中camera还有很多十分复杂的东西,例如ISP,上层图像的形成,camera数据的传输等等。

























    

camer驱动模块加载分析

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原文地址:http://blog.csdn.net/bsxiaomage/article/details/51290312

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