Commit 31fd4b9d authored Aug 18, 2022 by Daniel Lezcano

thermal/drivers/imx_sc: Rely on the platform data to get the resource id



Currently the imx_sc driver is reimplementing part of the thermal zone
parsing from the thermal OF tree code to get the sensor id associated
with a thermal zone sensor.

The driver platform specific code should know what sensor is present
and not rely on the thermal zone description to do a discovery. Well
that is arguable but all the other drivers have a per platform data
telling what sensor id to use.

The imx_sc thermal driver is the only one using a different
approach. Not invalid but forcing to keep a specific function
'thermal_zone_of_get_sensor_id()' to get the sensor id for a specific
thermal zone as the self-explanatory function tells and having device
tree code inside the driver.

The thermal OF code had a rework and remains now self-encapsulated
with a register/unregister functions and their 'devm' variants, except
for the function mentioned above.

After investigating, it appears the imx_sc sensor is defined in
arch/arm64/boot/dts/freescale/imx8qxp.dtsi:

which defines the cpu-thermal zone with the id: IMX_SC_R_SYSTEM

This dtsi is included by:
 - imx8qxp-ai_ml.dts
 - imx8qxp-colibri.dtsi
 - imx8qxp-mek.dts

The two first ones do not define more thermal zones
The third one adds the pmic-thermal0 zone with id: IMX_SC_R_PMIC_0

The thermal OF code returns -ENODEV if the thermal zone registration
with a specific id fails because the description is not available in
the DT for such a sensor id. In this case we continue with the other
ids without bailing out with an error.

So we can build for the 'fsl,imx-sc-thermal' a compatible data, an
array of sensor ids containing IMX_SC_R_SYSTEM and IMX_SC_R_PMIC_0.

The latter won't be found but that will not result in an error but a
normal case where we continue the initialization with other ids.

Just to clarify, it is what the thermal framework does and what the
other drivers are expecting: when a registration fails with -ENODEV
this is not an error but a case where the description is not found in
the device tree, that be can the entire thermal zones description or a
specific thermal zone with an unknown id.

There is one small functional change but without impact. When there is
no 'thermal-zones' description the probe function was returning
'-ENODEV', now it returns zero. When a thermal zone fails to register
with an error different from '-ENODEV', the error is detected and
returned.

Change the code accordingly and remove the OF code from the driver.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220818082316.2717095-1-daniel.lezcano@linaro.org

parent 2e70ea7f

drivers/thermal/imx_sc_thermal.c

+33 −35

Original line number	Diff line number	Diff line
		@@ -76,59 +76,55 @@ static const struct thermal_zone_device_ops imx_sc_thermal_ops = {

		static int imx_sc_thermal_probe(struct platform_device *pdev)
		{
		struct device_node np, child, *sensor_np;
		struct imx_sc_sensor *sensor;
		int ret;
		const int *resource_id;
		int i, ret;

		ret = imx_scu_get_handle(&thermal_ipc_handle);
		if (ret)
		return ret;

		np = of_find_node_by_name(NULL, "thermal-zones");
		if (!np)
		return -ENODEV;
		resource_id = of_device_get_match_data(&pdev->dev);
		if (!resource_id)
		return -EINVAL;

		sensor_np = of_node_get(pdev->dev.of_node);
		for (i = 0; resource_id[i] > 0; i++) {

		for_each_available_child_of_node(np, child) {
		sensor = devm_kzalloc(&pdev->dev, sizeof(*sensor), GFP_KERNEL);
		if (!sensor) {
		of_node_put(child);
		ret = -ENOMEM;
		goto put_node;
		}
		if (!sensor)
		return -ENOMEM;

		ret = thermal_zone_of_get_sensor_id(child,
		sensor_np,
		&sensor->resource_id);
		if (ret < 0) {
		dev_err(&pdev->dev,
		"failed to get valid sensor resource id: %d\n",
		ret);
		of_node_put(child);
		break;
		}
		sensor->resource_id = resource_id[i];

		sensor->tzd = devm_thermal_of_zone_register(&pdev->dev,
		sensor->resource_id,
		sensor,
		&imx_sc_thermal_ops);
		sensor->tzd = devm_thermal_of_zone_register(&pdev->dev, sensor->resource_id,
		sensor, &imx_sc_thermal_ops);
		if (IS_ERR(sensor->tzd)) {
		dev_err(&pdev->dev, "failed to register thermal zone\n");
		/*
		* Save the error value before freeing the
		* sensor pointer, otherwise we endup with a
		* use-after-free error
		*/
		ret = PTR_ERR(sensor->tzd);
		of_node_put(child);
		break;

		devm_kfree(&pdev->dev, sensor);

		/*
		* The thermal framework notifies us there is
		* no thermal zone description for such a
		* sensor id
		*/
		if (ret == -ENODEV)
		continue;

		dev_err(&pdev->dev, "failed to register thermal zone\n");
		return ret;
		}

		if (devm_thermal_add_hwmon_sysfs(sensor->tzd))
		dev_warn(&pdev->dev, "failed to add hwmon sysfs attributes\n");
		}

		put_node:
		of_node_put(sensor_np);
		of_node_put(np);

		return ret;
		return 0;
		}

		static int imx_sc_thermal_remove(struct platform_device *pdev)
		@@ -136,8 +132,10 @@ static int imx_sc_thermal_remove(struct platform_device *pdev)
		return 0;
		}

		static int imx_sc_sensors[] = { IMX_SC_R_SYSTEM, IMX_SC_R_PMIC_0, -1 };

		static const struct of_device_id imx_sc_thermal_table[] = {
		{ .compatible = "fsl,imx-sc-thermal", },
		{ .compatible = "fsl,imx-sc-thermal", .data = imx_sc_sensors },
		{}
		};
		MODULE_DEVICE_TABLE(of, imx_sc_thermal_table);