高通camera马达驱动工作流程

来源：互联网发布：软件架构.pdf 编辑：程序博客网时间：2024/06/02 19:16

手机自动对焦功能是通过将摄像头锁入音圈马达来实现的，音圈马达简称（VCM），它主要有线圈，磁铁组和弹片构成，线圈通过上下两个弹片固定在磁铁组成，当给线圈通电时，线圈会产生磁场，线圈磁场和磁石组相互作用，线圈会向上移动，而锁在线圈里的摄像头便一起移动，当断电时，线圈在弹片弹力下返回，这样就实现了自动对焦功能。

这里重点是讲解一下关于高通平台camera的马达驱动，和驱动驱动一样，高通平台端的马达的入口函数也是module_init（）；

module_init(msm_actuator_init_module);

msm_actuator_init_module（）函数主要是实现了两个功能：一个是通过platform_driver_register函数注册驱动（msm_actuator_platform_driver），还有一个是将msm_actuator_i2c_driver挂载i2c总线上；

static struct platform_driver msm_actuator_platform_driver = {

.probe = msm_actuator_platform_probe, //注册成功后就会调用这个探测函数（重要）

.driver = {

.name = "qcom,actuator",

.owner = THIS_MODULE,

.of_match_table = msm_actuator_dt_match, //通过设备树的compatible匹配资源，具体见下图

}

<span style="font-size:18px;color:#33cc00;">static int32_t msm_actuator_platform_probe(struct platform_device *pdev){      ··············    rc = of_property_read_u32((&pdev->dev)->of_node, "cell-index",        &pdev->id);                </span><span style="font-size:18px;color:#003333;">//获取设备资源信息</span><span style="font-size:18px;color:#33cc00;">    CDBG("cell-index %d, rc %d\n", pdev->id, rc);    if (rc < 0) {        kfree(msm_actuator_t);        pr_err("failed rc %d\n", rc);        return rc;    }</span>

<span style="color: rgb(51, 204, 0);font-size:18px; line-height: 1.5; font-family: 微软雅黑;">     /*初始化msm_actuator_t*/</span>

<span style="color: rgb(51, 204, 0);font-size:18px; line-height: 1.5; font-family: 微软雅黑;">   msm_actuator_t->act_v4l2_subdev_ops = &</span><span style="font-size:18px; line-height: 1.5; font-family: 微软雅黑;"><span style="color:#ff0000;">msm_actuator_subdev_ops</span></span><span style="color: rgb(51, 204, 0);font-size:18px; line-height: 1.5; font-family: 微软雅黑;">;</span>

<span style="color: rgb(51, 204, 0);font-size:18px; line-height: 1.5; font-family: 微软雅黑;">    msm_actuator_t->actuator_mutex = &msm_actuator_mutex;        //互斥锁</span>

<span style="color: rgb(51, 204, 0);font-size:18px; line-height: 1.5; font-family: 微软雅黑;">    msm_actuator_t->cam_name = pdev->id;</span>

<span style="font-size:18px;color:#33cc00;">    /* Set platform device handle */    msm_actuator_t->pdev = pdev;    /* Set device type as platform device */    msm_actuator_t->act_device_type = MSM_CAMERA_PLATFORM_DEVICE;    msm_actuator_t->i2c_client.i2c_func_tbl = &msm_sensor_cci_func_tbl;    msm_actuator_t->i2c_client.cci_client = kzalloc(sizeof(        struct msm_camera_cci_client), GFP_KERNEL);    if (!msm_actuator_t->i2c_client.cci_client) {        kfree(msm_actuator_t->vreg_cfg.cam_vreg);        kfree(msm_actuator_t);        pr_err("failed no memory\n");        return -ENOMEM;    }    cci_client = msm_actuator_t->i2c_client.cci_client;    cci_client->cci_subdev = msm_cci_get_subdev();    cci_client->cci_i2c_master = msm_actuator_t->cci_master;    v4l2_subdev_init(&msm_actuator_t->msm_sd.sd,        msm_actuator_t->act_v4l2_subdev_ops);    v4l2_set_subdevdata(&msm_actuator_t->msm_sd.sd, msm_actuator_t);    msm_actuator_t->msm_sd.sd.internal_ops = &msm_actuator_internal_ops;    msm_actuator_t->msm_sd.sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;    snprintf(msm_actuator_t->msm_sd.sd.name,        ARRAY_SIZE(msm_actuator_t->msm_sd.sd.name), "msm_actuator");    media_entity_init(&msm_actuator_t->msm_sd.sd.entity, 0, NULL, 0);    msm_actuator_t->msm_sd.sd.entity.type = MEDIA_ENT_T_V4L2_SUBDEV;    msm_actuator_t->msm_sd.sd.entity.group_id = MSM_CAMERA_SUBDEV_ACTUATOR;    msm_actuator_t->msm_sd.close_seq = MSM_SD_CLOSE_2ND_CATEGORY | 0x2;    msm_sd_register(&msm_actuator_t->msm_sd);    msm_actuator_t->actuator_state = ACT_DISABLE_STATE;    msm_cam_copy_v4l2_subdev_fops(&msm_actuator_v4l2_subdev_fops);#ifdef CONFIG_COMPAT    msm_actuator_v4l2_subdev_fops.compat_ioctl32 =        msm_actuator_subdev_fops_ioctl;#endif    msm_actuator_t->msm_sd.sd.devnode->fops =        &msm_actuator_v4l2_subdev_fops;    CDBG("Exit\n");    return rc;}</span><span style="font-size: 14px;"></span>

static struct msm_actuator msm_vcm_actuator_table = {    .act_type = ACTUATOR_VCM,                      //类型：音圈马达    .func_tbl = {        .actuator_init_step_table = msm_actuator_init_step_table,                       .actuator_move_focus = msm_actuator_move_focus,        .actuator_write_focus = msm_actuator_write_focus,        .actuator_set_default_focus = msm_actuator_set_default_focus,        .actuator_init_focus = msm_actuator_init_focus,        .actuator_parse_i2c_params = msm_actuator_parse_i2c_params,        .actuator_set_position = msm_actuator_set_position,        .actuator_park_lens = msm_actuator_park_lens,    },};

msm_actuator_init_step_table（）函数主要是初始化step_table：

1、先通过ADC多少位确定max_code_size，例如10位的就是1024；

2、a_ctrl->step_position_table = NULL;清空位置表并重新设置；

3、cur_code = set_info->af_tuning_params.initial_code;设置最初的编码；

4、其他

msm_actuator_move_focus：主要是计算出位置，然后通过i2c发送命令移动焦距：

rc = a_ctrl->i2c_client.i2c_func_tbl->i2c_write_table_w_microdelay(

&a_ctrl->i2c_client, &reg_setting);

msm_actuator_write_focus：

Write code based on damping_code_step in a loop

msm_actuator_set_default_focus设置默认的焦距：

rc = a_ctrl->func_tbl->actuator_move_focus(a_ctrl, move_params);

msm_actuator_init_focus初始化对焦：

设置i2c通信的地址和数据类型（word或者byte型）；

i2c的通信方式MSM_ACT_WRITE或者MSM_ACT_POLL；

根据传入的参数进行初始化。

msm_actuator_parse_i2c_params解析i2c参数：就是把各组i2c通信数据和地址解析到i2c_tbl中

value = (next_lens_position << write_arr[i].data_shift) | ((hw_dword & write_arr[i].hw_mask) >>write_arr[i].hw_shift);

i2c_byte1 = (value & 0xFF00) >> 8;

i2c_byte2 = value & 0xFF;

把i2c的地址和数据解析存放到a_ctrl->i2c_reg_tbl中

static void msm_actuator_parse_i2c_params(struct msm_actuator_ctrl_t *a_ctrl,

int16_t next_lens_position, uint32_t hw_params, uint16_t delay)

{

struct msm_actuator_reg_params_t *write_arr = a_ctrl->reg_tbl;

uint32_t hw_dword = hw_params;

uint16_t i2c_byte1 = 0, i2c_byte2 = 0;

uint16_t value = 0;

uint32_t size = a_ctrl->reg_tbl_size, i = 0;

struct msm_camera_i2c_reg_array *i2c_tbl = a_ctrl->i2c_reg_tbl;

CDBG("Enter\n");

for (i = 0; i < size; i++) {

/* check that the index into i2c_tbl cannot grow larger that

the allocated size of i2c_tbl */

if ((a_ctrl->total_steps + 1) < (a_ctrl->i2c_tbl_index)) {

break;

}

//先是判断是否属于DAC类型，如果不属于，则有：

i2c_byte1 = write_arr[i].reg_addr;

i2c_byte2 = (hw_dword & write_arr[i].hw_mask) >>write_arr[i].hw_shift;

这个说明不属于ＤＡＣ所以直接简第一位进行地址，第二位通过上面运算得到数据value作为byte2

如果属于ＤＡＣ类型，value = (next_lens_position <<

write_arr[i].data_shift) | ((hw_dword & write_arr[i].hw_mask) >> write_arr[i].hw_shift);

然后判断是其寄存器地址是否等于0xFFF，如果不等于0xFFFF，则说明不是具体的某个寄存器，则：

i2c_byte1 = write_arr[i].reg_addr; i2c_byte2 = value;

如果ＤＡＣ的寄存器不止一个的时候，i2c_byte2 = value & 0xFF;先存放到i2c_tbl中，然后第二个（貌似这里最多都只支持两个集训器）

如果寄存器的地址就是0xFFFF的时候，i2c_byte1 = (value & 0xFF00) >> 8;i2c_byte2 = value & 0xFF;高八位作为地址，第八位作为数据传输

代码实现见如下：

if (write_arr[i].reg_write_type == MSM_ACTUATOR_WRITE_DAC) {

value = (next_lens_position << write_arr[i].data_shift) |((hw_dword & write_arr[i].hw_mask) >> write_arr[i].hw_shift);

if (write_arr[i].reg_addr != 0xFFFF) {

i2c_byte1 = write_arr[i].reg_addr;

i2c_byte2 = value;

if (size != (i+1)) {

i2c_byte2 = value & 0xFF;

CDBG("byte1:0x%x, byte2:0x%x\n",

i2c_byte1, i2c_byte2);

i2c_tbl[a_ctrl->i2c_tbl_index].

reg_addr = i2c_byte1;

i2c_tbl[a_ctrl->i2c_tbl_index].

reg_data = i2c_byte2;

i2c_tbl[a_ctrl->i2c_tbl_index].

delay = 0;

a_ctrl->i2c_tbl_index++;

i++;

i2c_byte1 = write_arr[i].reg_addr;

i2c_byte2 = (value & 0xFF00) >> 8;

}

} else {

i2c_byte1 = (value & 0xFF00) >> 8;

i2c_byte2 = value & 0xFF;

}

else {

i2c_byte1 = write_arr[i].reg_addr;

i2c_byte2 = (hw_dword & write_arr[i].hw_mask) >>

write_arr[i].hw_shift;

}

CDBG("i2c_byte1:0x%x, i2c_byte2:0x%x\n", i2c_byte1, i2c_byte2);

i2c_tbl[a_ctrl->i2c_tbl_index].reg_addr = i2c_byte1;

i2c_tbl[a_ctrl->i2c_tbl_index].reg_data = i2c_byte2;

i2c_tbl[a_ctrl->i2c_tbl_index].delay = delay;

a_ctrl->i2c_tbl_index++;

}

CDBG("Exit\n");

}

0 0