thermal driver为zone device 添加sensor

前面讲过在thermal_init->of_parse_thermal_zones的时候已经从dts中建好了zone device，并绑定了cool device
int __init of_parse_thermal_zones(void)
{
	struct device_node *np, *child;
	struct __thermal_zone *tz;
	struct thermal_zone_device_ops *ops;
//找到zone device
	np = of_find_node_by_name(NULL, "thermal-zones");
	if (!np) {
		pr_debug("unable to find thermal zones\n");
		return 0; /* Run successfully on systems without thermal DT */
	}

	for_each_available_child_of_node(np, child) {
		struct thermal_zone_device *zone;
		struct thermal_zone_params *tzp;
		int i, mask = 0;
		u32 prop;
//从dts中parse值后赋值给tzp
		tz = thermal_of_build_thermal_zone(child);
		if (IS_ERR(tz)) {
			pr_err("failed to build thermal zone %s: %ld\n",
			       child->name,
			       PTR_ERR(tz));
			continue;
		}

		ops = kmemdup(&of_thermal_ops, sizeof(*ops), GFP_KERNEL);
		if (!ops)
			goto exit_free;

		tzp = kzalloc(sizeof(*tzp), GFP_KERNEL);
		if (!tzp) {
			kfree(ops);
			goto exit_free;
		}

		/* No hwmon because there might be hwmon drivers registering */
		tzp->no_hwmon = true;

		if (!of_property_read_u32(child, "sustainable-power", &prop))
			tzp->sustainable_power = prop;

		for (i = 0; i < tz->ntrips; i++)
			mask |= 1 << i;

		/* these two are left for temperature drivers to use */
		tzp->slope = tz->slope;
		tzp->offset = tz->offset;
//注册zone device 并绑定cool device
		zone = thermal_zone_device_register(child->name, tz->ntrips,
						    mask, tz,
						    ops, tzp,
						    tz->passive_delay,
						    tz->polling_delay);
		if (IS_ERR(zone)) {
			pr_err("Failed to build %s zone %ld\n", child->name,
			       PTR_ERR(zone));
			kfree(tzp);
			kfree(ops);
			of_thermal_free_zone(tz);
			/* attempting to build remaining zones still */
		}
	}
	of_node_put(np);

	return 0;
}
但是需要注意的是，这里并没有为zone device 添加sensor，也就是说zone device不能得到目前的温度，因此thermal driver主要责任就是给zone device添加sensor。
这里以下面的thermal 驱动为例
static int hisi_thermal_probe(struct platform_device *pdev)
{
	struct hisi_thermal_data *data;
	struct resource *res;
	int i;
	int ret;

//注册中断线程化
	ret = devm_request_threaded_irq(&pdev->dev, data->irq,
					hisi_thermal_alarm_irq,
					hisi_thermal_alarm_irq_thread,
					0, "hisi_thermal", data);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to request alarm irq: %d\n", ret);
		return ret;
	}

	
//调用hisi_thermal_register_sensor 为zone device添加sensor来获取温度
	for (i = 0; i < HISI_MAX_SENSORS; ++i) {
		ret = hisi_thermal_register_sensor(pdev, data,
						   &data->sensors[i], i);
		if (ret)
			dev_err(&pdev->dev,
				"failed to register thermal sensor: %d\n", ret);
		else
			hisi_thermal_toggle_sensor(&data->sensors[i], true);
	}

	return 0;
}
继续看看hisi_thermal_register_sensor
static int hisi_thermal_register_sensor(struct platform_device *pdev,
					struct hisi_thermal_data *data,
					struct hisi_thermal_sensor *sensor,
					int index)
{

//调用devm_thermal_zone_of_sensor_register->thermal_zone_of_sensor_register 来为已经存在的zone device添加sensor，这里的hisi_of_thermal_ops 就是sensor 获取温度的ops
	sensor->tzd = devm_thermal_zone_of_sensor_register(&pdev->dev,
				sensor->id, sensor, &hisi_of_thermal_ops);
	if (IS_ERR(sensor->tzd)) {
		ret = PTR_ERR(sensor->tzd);
		sensor->tzd = NULL;
		dev_err(&pdev->dev, "failed to register sensor id %d: %d\n",
			sensor->id, ret);
		return ret;
	}


}
struct thermal_zone_device *
thermal_zone_of_sensor_register(struct device *dev, int sensor_id, void *data,
				const struct thermal_zone_of_device_ops *ops)
{
	struct device_node *np, *child, *sensor_np;
	struct thermal_zone_device *tzd = ERR_PTR(-ENODEV);
//找到zone device在dts中的node
	np = of_find_node_by_name(NULL, "thermal-zones");
	if (!np)
		return ERR_PTR(-ENODEV);

	if (!dev || !dev->of_node) {
		of_node_put(np);
		return ERR_PTR(-EINVAL);
	}

	sensor_np = of_node_get(dev->of_node);

	for_each_available_child_of_node(np, child) {
		struct of_phandle_args sensor_specs;
		int ret, id;

		/* For now, thermal framework supports only 1 sensor per zone */
		ret = of_parse_phandle_with_args(child, "thermal-sensors",
						 "#thermal-sensor-cells",
						 0, &sensor_specs);
		if (ret)
			continue;
//每个zone 只能有一个sensor
		if (sensor_specs.args_count >= 1) {
			id = sensor_specs.args[0];
			WARN(sensor_specs.args_count > 1,
			     "%s: too many cells in sensor specifier %d\n",
			     sensor_specs.np->name, sensor_specs.args_count);
		} else {
			id = 0;
		}
//找到目前sensor对应的zone device。找到后通过thermal_zone_of_add_sensor 给zone 添加sensor
		if (sensor_specs.np == sensor_np && id == sensor_id) {
			tzd = thermal_zone_of_add_sensor(child, sensor_np,
							 data, ops);
			if (!IS_ERR(tzd))
				tzd->ops->set_mode(tzd, THERMAL_DEVICE_ENABLED);

			of_node_put(sensor_specs.np);
			of_node_put(child);
			goto exit;
		}
		of_node_put(sensor_specs.np);
	}

}

static struct thermal_zone_device *
thermal_zone_of_add_sensor(struct device_node *zone,
			   struct device_node *sensor, void *data,
			   const struct thermal_zone_of_device_ops *ops)
{
	struct thermal_zone_device *tzd;
	struct __thermal_zone *tz;
//这部是关键，根据name找到zone device
	tzd = thermal_zone_get_zone_by_name(zone->name);
	if (IS_ERR(tzd))
		return ERR_PTR(-EPROBE_DEFER);

	tz = tzd->devdata;

	if (!ops)
		return ERR_PTR(-EINVAL);

	mutex_lock(&tzd->lock);
	tz->ops = ops;
	tz->sensor_data = data;
//为zone device的赋值，后面就直接通过tzd->ops->get_temp 来获取温度
	tzd->ops->get_temp = of_thermal_get_temp;
	tzd->ops->get_trend = of_thermal_get_trend;
}
static int of_thermal_get_temp(struct thermal_zone_device *tz,
			       int *temp)
{
	struct __thermal_zone *data = tz->devdata;

	if (!data->ops->get_temp)
		return -EINVAL;
//可见又是调用data->ops->get_temp，这里的data就是hisi_of_thermal_ops
	return data->ops->get_temp(data->sensor_data, temp);
}
static struct thermal_zone_of_device_ops hisi_of_thermal_ops = {
	.get_temp = hisi_thermal_get_temp,
};
hisi_thermal_get_temp->hisi_thermal_get_sensor_temp得到温度。查看hisi_thermal_get_sensor_temp的code会发现基本是在读取硬件寄存器