thermal: exynos: Fix first temperature read after registering sensor

commit 9e4249b4 upstream.

Thermal core could not read the temperature after registering the
thermal sensor with thermal_zone_of_sensor_register() because the driver
was not yet initialized.

The call trace looked like:
    exynos_tmu_probe()
        thermal_zone_of_sensor_register()
            of_thermal_set_mode()
                thermal_zone_device_update()
                    exynos_get_temp()
                        if (!data->tmu_read) return -EINVAL;
        exynos_map_dt_data()
            data->tmu_read = ...

This produced an error in dmesg:
thermal thermal_zone0: failed to read out thermal zone (-22)

Register the thermal_zone_device later, after parsing Device Tree and
enabling necessary clocks, but before calling exynos_tmu_initialize()
which uses the registered thermal_zone_device.
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>
Tested-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: 3b6a1a80 ("thermal: samsung: core: Exynos TMU rework to use device tree for configuration")
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

drivers/thermal/samsung/exynos_tmu.c

@@ -1290,13 +1290,6 @@ static int exynos_tmu_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, data);
 	mutex_init(&data->lock);
 
-	data->tzd = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
-						    &exynos_sensor_ops);
-	if (IS_ERR(data->tzd)) {
-		pr_err("thermal: tz: %p ERROR\n", data->tzd);
-		return PTR_ERR(data->tzd);
-	}
-
 	/*
 	 * Try enabling the regulator if found
 	 * TODO: Add regulator as an SOC feature, so that regulator enable
@@ -1366,21 +1359,36 @@ static int exynos_tmu_probe(struct platform_device *pdev)
 		break;
 	};
 
+	/*
+	 * data->tzd must be registered before calling exynos_tmu_initialize(),
+	 * requesting irq and calling exynos_tmu_control().
+	 */
+	data->tzd = thermal_zone_of_sensor_register(&pdev->dev, 0, data,
+						    &exynos_sensor_ops);
+	if (IS_ERR(data->tzd)) {
+		ret = PTR_ERR(data->tzd);
+		dev_err(&pdev->dev, "Failed to register sensor: %d\n", ret);
+		goto err_sclk;
+	}
+
 	ret = exynos_tmu_initialize(pdev);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to initialize TMU\n");
-		goto err_sclk;
+		goto err_thermal;
 	}
 
 	ret = devm_request_irq(&pdev->dev, data->irq, exynos_tmu_irq,
 		IRQF_TRIGGER_RISING | IRQF_SHARED, dev_name(&pdev->dev), data);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to request irq: %d\n", data->irq);
-		goto err_sclk;
+		goto err_thermal;
 	}
 
 	exynos_tmu_control(pdev, true);
 	return 0;
+
+err_thermal:
+	thermal_zone_of_sensor_unregister(&pdev->dev, data->tzd);
 err_sclk:
 	clk_disable_unprepare(data->sclk);
 err_clk:
@@ -1391,7 +1399,6 @@ static int exynos_tmu_probe(struct platform_device *pdev)
 err_sensor:
 	if (!IS_ERR_OR_NULL(data->regulator))
 		regulator_disable(data->regulator);
-	thermal_zone_of_sensor_unregister(&pdev->dev, data->tzd);
 
 	return ret;
 }