MP157 linux ov5640 Driver

dev

struct ov5640_dev {
	struct i2c_client *i2c_client;//需要iic 操作
	struct v4l2_subdev sd;//v4l2 接口
	struct media_pad pad;//需要一个pad?
	struct v4l2_fwnode_endpoint ep; /* the parsed DT endpoint info */
	struct clk *xclk; /* system clock to OV5640 */
	u32 xclk_freq;

	struct regulator_bulk_data supplies[OV5640_NUM_SUPPLIES];// 电源控制
	struct gpio_desc *reset_gpio;
	struct gpio_desc *pwdn_gpio;
	bool   upside_down;// 上下翻转

	/* lock to protect all members below */
	struct mutex lock; //一把锁  

	int power_count;//上电状态 update the power state.

	struct v4l2_mbus_framefmt fmt;//media bus fmt
	bool pending_fmt_change; //停下来改

	const struct ov5640_mode_info *current_mode;//current
	const struct ov5640_mode_info *last_mode;//last
	enum ov5640_frame_rate current_fr;//fps
	struct v4l2_fract frame_interval;//

	struct ov5640_ctrls ctrls;//对焦 曝光 白平衡 。。。

	u32 prev_sysclk, prev_hts;//?
	//line_length = Hsync = Dummy Pixel = HTotal = HTS = H_Size + H_Blank 
	//会占用曝光时间，即可以通过调节H_Blank, 调节行长
	u32 ae_low, ae_high, ae_target; //ae 自爆

	bool pending_mode_change;
	bool streaming;// streaming enable
};

probe

static int ov5640_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct fwnode_handle *endpoint;
	struct ov5640_dev *sensor;//  senseor 5640
	struct v4l2_mbus_framefmt *fmt;
	u32 rotation;
	int ret;

	sensor = devm_kzalloc(dev, sizeof(*sensor), GFP_KERNEL);
	if (!sensor)
		return -ENOMEM;

	sensor->i2c_client = client;// iic5

	/*
	 * default init sequence initialize sensor to
	 * YUV422 UYVY VGA@30fps
	 */
	fmt = &sensor->fmt;//指向它 修改它
	fmt->code = MEDIA_BUS_FMT_UYVY8_2X8;
	fmt->colorspace = V4L2_COLORSPACE_SRGB;
	fmt->ycbcr_enc = V4L2_MAP_YCBCR_ENC_DEFAULT(fmt->colorspace);
	fmt->quantization = V4L2_QUANTIZATION_FULL_RANGE;
	fmt->xfer_func = V4L2_MAP_XFER_FUNC_DEFAULT(fmt->colorspace);
	fmt->width = 640;
	fmt->height = 480;
	fmt->field = V4L2_FIELD_NONE;
	
	sensor->frame_interval.numerator = 1;//分子分母计算帧率
	sensor->frame_interval.denominator = ov5640_framerates[OV5640_30_FPS];//30
	sensor->current_fr = OV5640_30_FPS;
	sensor->current_mode =
		&ov5640_mode_data[OV5640_MODE_VGA_640_480];
	sensor->last_mode = sensor->current_mode;//640 480 vga default

	sensor->ae_target = 52;//曝光度  计算

	/* optional indication of physical rotation of sensor */
	ret = fwnode_property_read_u32(dev_fwnode(&client->dev), "rotation",
				       &rotation);// 180 or 0
	if (!ret) {
		switch (rotation) {
		case 180:
			sensor->upside_down = true;
			/* fall through */
		case 0:
			break;
		default:
			dev_warn(dev, "%u degrees rotation is not supported, ignoring...\n",
				 rotation);
		}
	}

	endpoint = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev),
						  NULL);//get 拿过来
	if (!endpoint) {
		dev_err(dev, "endpoint node not found\n");
		return -EINVAL;
	}

	ret = v4l2_fwnode_endpoint_parse(endpoint, &sensor->ep);
	fwnode_handle_put(endpoint);//put 释放  
	if (ret) {
		dev_err(dev, "Could not parse endpoint\n");
		return ret;
	}

	/* get system clock (xclk) */
	sensor->xclk = devm_clk_get(dev, "xclk");
	if (IS_ERR(sensor->xclk)) {
		dev_err(dev, "failed to get xclk\n");
		return PTR_ERR(sensor->xclk);
	}

	sensor->xclk_freq = clk_get_rate(sensor->xclk);//24 000 000
	if (sensor->xclk_freq < OV5640_XCLK_MIN ||
	    sensor->xclk_freq > OV5640_XCLK_MAX) {
		dev_err(dev, "xclk frequency out of range: %d Hz\n",
			sensor->xclk_freq);
		return -EINVAL;
	}

	/* request optional power down pin */
	sensor->pwdn_gpio = devm_gpiod_get_optional(dev, "powerdown",
						    GPIOD_OUT_HIGH);
	if (IS_ERR(sensor->pwdn_gpio))
		return PTR_ERR(sensor->pwdn_gpio);

	/* request optional reset pin */
	sensor->reset_gpio = devm_gpiod_get_optional(dev, "reset",
						     GPIOD_OUT_HIGH);
	if (IS_ERR(sensor->reset_gpio))
		return PTR_ERR(sensor->reset_gpio);

	v4l2_i2c_subdev_init(&sensor->sd, client, &ov5640_subdev_ops);//init subdev

	sensor->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
			    V4L2_SUBDEV_FL_HAS_EVENTS;
	sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
	sensor->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
	ret = media_entity_pads_init(&sensor->sd.entity, 1, &sensor->pad);
	if (ret)
		return ret;

	ret = ov5640_get_regulators(sensor);
	if (ret)
		return ret;

	mutex_init(&sensor->lock);//mutex init

	ret = ov5640_check_chip_id(sensor);//chack id
	if (ret)
		goto entity_cleanup;

	ret = ov5640_init_controls(sensor);//ctrl init
	if (ret)
		goto entity_cleanup;

	ret = v4l2_async_register_subdev_sensor_common(&sensor->sd);//reg sd
	if (ret)
		goto free_ctrls;

	return 0;

free_ctrls:
	v4l2_ctrl_handler_free(&sensor->ctrls.handler);
entity_cleanup:
	mutex_destroy(&sensor->lock);
	media_entity_cleanup(&sensor->sd.entity);
	return ret;
}

chip id

static int ov5640_check_chip_id(struct ov5640_dev *sensor)
{
	struct i2c_client *client = sensor->i2c_client;
	int ret = 0;
	u16 chip_id;

	ret = ov5640_set_power_on(sensor);
	if (ret)
		return ret;

	ret = ov5640_read_reg16(sensor, OV5640_REG_CHIP_ID, &chip_id);//read chip id
	if (ret) {
		dev_err(&client->dev, "%s: failed to read chip identifier\n",
			__func__);
		goto power_off;
	}

	if (chip_id != 0x5640) {
		dev_err(&client->dev, "%s: wrong chip identifier, expected 0x5640, got 0x%x\n",
			__func__, chip_id);
		ret = -ENXIO;
	}

power_off:
	ov5640_set_power_off(sensor);
	return ret;
}

pwr_on

static int ov5640_set_power_on(struct ov5640_dev *sensor)
{
	struct i2c_client *client = sensor->i2c_client;
	int ret;

	ret = clk_prepare_enable(sensor->xclk);
	if (ret) {
		dev_err(&client->dev, "%s: failed to enable clock\n",
			__func__);
		return ret;
	}

	ret = regulator_bulk_enable(OV5640_NUM_SUPPLIES,
				    sensor->supplies);
	if (ret) {
		dev_err(&client->dev, "%s: failed to enable regulators\n",
			__func__);
		goto xclk_off;
	}

	ov5640_reset(sensor);
	ov5640_power(sensor, true);

	ret = ov5640_init_slave_id(sensor);//多个slave时 改成不同0x3c的id
	if (ret)
		goto power_off;

	return 0;

power_off:
	ov5640_power(sensor, false);
	regulator_bulk_disable(OV5640_NUM_SUPPLIES, sensor->supplies);
xclk_off:
	clk_disable_unprepare(sensor->xclk);
	return ret;
}