thermal: add stm32 thermal driver

Add support for DTS thermal sensor that can be
found on some STM32 platforms.

This driver is based on OF and works in interrupt
mode.

It offers two temperature trip points:
passive and critical. The first is intended for
passive cooling notification while the second is
used for over-temperature reset.

Signed-off-by: David Hernandez Sanchez <david.hernandezsanchez@st.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

1 files changed, 760 insertions, 0 deletions

diff --git a/drivers/thermal/st/stm_thermal.c b/drivers/thermal/st/stm_thermal.c
new file mode 100644
index 000000000000..47623da0f91b
--- /dev/null
+++ b/drivers/thermal/st/stm_thermal.c
@@ -0,0 +1,760 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
+ * Author: David Hernandez Sanchez <david.hernandezsanchez@st.com> for
+ * STMicroelectronics.
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#include "../thermal_core.h"
+#include "../thermal_hwmon.h"
+
+/* DTS register offsets */
+#define DTS_CFGR1_OFFSET	0x0
+#define DTS_T0VALR1_OFFSET	0x8
+#define DTS_RAMPVALR_OFFSET	0X10
+#define DTS_ITR1_OFFSET		0x14
+#define DTS_DR_OFFSET		0x1C
+#define DTS_SR_OFFSET		0x20
+#define DTS_ITENR_OFFSET	0x24
+#define DTS_CIFR_OFFSET		0x28
+
+/* DTS_CFGR1 register mask definitions */
+#define HSREF_CLK_DIV_MASK	GENMASK(30, 24)
+#define TS1_SMP_TIME_MASK	GENMASK(19, 16)
+#define TS1_INTRIG_SEL_MASK	GENMASK(11, 8)
+
+/* DTS_T0VALR1 register mask definitions */
+#define TS1_T0_MASK		GENMASK(17, 16)
+#define TS1_FMT0_MASK		GENMASK(15, 0)
+
+/* DTS_RAMPVALR register mask definitions */
+#define TS1_RAMP_COEFF_MASK	GENMASK(15, 0)
+
+/* DTS_ITR1 register mask definitions */
+#define TS1_HITTHD_MASK		GENMASK(31, 16)
+#define TS1_LITTHD_MASK		GENMASK(15, 0)
+
+/* DTS_DR register mask definitions */
+#define TS1_MFREQ_MASK		GENMASK(15, 0)
+
+/* Less significant bit position definitions */
+#define TS1_T0_POS		16
+#define TS1_SMP_TIME_POS	16
+#define TS1_HITTHD_POS		16
+#define HSREF_CLK_DIV_POS	24
+
+/* DTS_CFGR1 bit definitions */
+#define TS1_EN			BIT(0)
+#define TS1_START		BIT(4)
+#define REFCLK_SEL		BIT(20)
+#define REFCLK_LSE		REFCLK_SEL
+#define Q_MEAS_OPT		BIT(21)
+#define CALIBRATION_CONTROL	Q_MEAS_OPT
+
+/* DTS_SR bit definitions */
+#define TS_RDY			BIT(15)
+/* Bit definitions below are common for DTS_SR, DTS_ITENR and DTS_CIFR */
+#define HIGH_THRESHOLD		BIT(2)
+#define LOW_THRESHOLD		BIT(1)
+
+/* Constants */
+#define ADJUST			100
+#define ONE_MHZ			1000000
+#define POLL_TIMEOUT		5000
+#define STARTUP_TIME		40
+#define TS1_T0_VAL0		30
+#define TS1_T0_VAL1		130
+#define NO_HW_TRIG		0
+
+/* The Thermal Framework expects millidegrees */
+#define mcelsius(temp)		((temp) * 1000)
+
+/* The Sensor expects oC degrees */
+#define celsius(temp)		((temp) / 1000)
+
+struct stm_thermal_sensor {
+	struct device *dev;
+	struct thermal_zone_device *th_dev;
+	enum thermal_device_mode mode;
+	struct clk *clk;
+	int high_temp;
+	int low_temp;
+	int temp_critical;
+	int temp_passive;
+	unsigned int low_temp_enabled;
+	int num_trips;
+	int irq;
+	unsigned int irq_enabled;
+	void __iomem *base;
+	int t0, fmt0, ramp_coeff;
+};
+
+static irqreturn_t stm_thermal_alarm_irq(int irq, void *sdata)
+{
+	struct stm_thermal_sensor *sensor = sdata;
+
+	disable_irq_nosync(irq);
+	sensor->irq_enabled = false;
+
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t stm_thermal_alarm_irq_thread(int irq, void *sdata)
+{
+	u32 value;
+	struct stm_thermal_sensor *sensor = sdata;
+
+	/* read IT reason in SR and clear flags */
+	value = readl_relaxed(sensor->base + DTS_SR_OFFSET);
+
+	if ((value & LOW_THRESHOLD) == LOW_THRESHOLD)
+		writel_relaxed(LOW_THRESHOLD, sensor->base + DTS_CIFR_OFFSET);
+
+	if ((value & HIGH_THRESHOLD) == HIGH_THRESHOLD)
+		writel_relaxed(HIGH_THRESHOLD, sensor->base + DTS_CIFR_OFFSET);
+
+	thermal_zone_device_update(sensor->th_dev, THERMAL_EVENT_UNSPECIFIED);
+
+	return IRQ_HANDLED;
+}
+
+static int stm_sensor_power_on(struct stm_thermal_sensor *sensor)
+{
+	int ret;
+	u32 value;
+
+	/* Enable sensor */
+	value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
+	value |= TS1_EN;
+	writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);
+
+	/*
+	 * The DTS block can be enabled by setting TSx_EN bit in
+	 * DTS_CFGRx register. It requires a startup time of
+	 * 40μs. Use 5 ms as arbitrary timeout.
+	 */
+	ret = readl_poll_timeout(sensor->base + DTS_SR_OFFSET,
+				 value, (value & TS_RDY),
+				 STARTUP_TIME, POLL_TIMEOUT);
+	if (ret)
+		return ret;
+
+	/* Start continuous measuring */
+	value = readl_relaxed(sensor->base +
+			      DTS_CFGR1_OFFSET);
+	value |= TS1_START;
+	writel_relaxed(value, sensor->base +
+		       DTS_CFGR1_OFFSET);
+
+	return 0;
+}
+
+static int stm_sensor_power_off(struct stm_thermal_sensor *sensor)
+{
+	u32 value;
+
+	/* Stop measuring */
+	value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
+	value &= ~TS1_START;
+	writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);
+
+	/* Ensure stop is taken into account */
+	usleep_range(STARTUP_TIME, POLL_TIMEOUT);
+
+	/* Disable sensor */
+	value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
+	value &= ~TS1_EN;
+	writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);
+
+	/* Ensure disable is taken into account */
+	return readl_poll_timeout(sensor->base + DTS_SR_OFFSET, value,
+				  !(value & TS_RDY),
+				  STARTUP_TIME, POLL_TIMEOUT);
+}
+
+static int stm_thermal_calibration(struct stm_thermal_sensor *sensor)
+{
+	u32 value, clk_freq;
+	u32 prescaler;
+
+	/* Figure out prescaler value for PCLK during calibration */
+	clk_freq = clk_get_rate(sensor->clk);
+	if (!clk_freq)
+		return -EINVAL;
+
+	prescaler = 0;
+	clk_freq /= ONE_MHZ;
+	if (clk_freq) {
+		while (prescaler <= clk_freq)
+			prescaler++;
+	}
+
+	value = readl_relaxed(sensor->base + DTS_CFGR1_OFFSET);
+
+	/* Clear prescaler */
+	value &= ~HSREF_CLK_DIV_MASK;
+
+	/* Set prescaler. pclk_freq/prescaler < 1MHz */
+	value |= (prescaler << HSREF_CLK_DIV_POS);
+
+	/* Select PCLK as reference clock */
+	value &= ~REFCLK_SEL;
+
+	/* Set maximal sampling time for better precision */
+	value |= TS1_SMP_TIME_MASK;
+
+	/* Measure with calibration */
+	value &= ~CALIBRATION_CONTROL;
+
+	/* select trigger */
+	value &= ~TS1_INTRIG_SEL_MASK;
+	value |= NO_HW_TRIG;
+
+	writel_relaxed(value, sensor->base + DTS_CFGR1_OFFSET);
+
+	return 0;
+}
+
+/* Fill in DTS structure with factory sensor values */
+static int stm_thermal_read_factory_settings(struct stm_thermal_sensor *sensor)
+{
+	/* Retrieve engineering calibration temperature */
+	sensor->t0 = readl_relaxed(sensor->base + DTS_T0VALR1_OFFSET) &
+					TS1_T0_MASK;
+	if (!sensor->t0)
+		sensor->t0 = TS1_T0_VAL0;
+	else
+		sensor->t0 = TS1_T0_VAL1;
+
+	/* Retrieve fmt0 and put it on Hz */
+	sensor->fmt0 = ADJUST * readl_relaxed(sensor->base + DTS_T0VALR1_OFFSET)
+					      & TS1_FMT0_MASK;
+
+	/* Retrieve ramp coefficient */
+	sensor->ramp_coeff = readl_relaxed(sensor->base + DTS_RAMPVALR_OFFSET) &
+					   TS1_RAMP_COEFF_MASK;
+
+	if (!sensor->fmt0 || !sensor->ramp_coeff) {
+		dev_err(sensor->dev, "%s: wrong setting\n", __func__);
+		return -EINVAL;
+	}
+
+	dev_dbg(sensor->dev, "%s: T0 = %doC, FMT0 = %dHz, RAMP_COEFF = %dHz/oC",
+		__func__, sensor->t0, sensor->fmt0, sensor->ramp_coeff);
+
+	return 0;
+}
+
+static int stm_thermal_calculate_threshold(struct stm_thermal_sensor *sensor,
+					   int temp, u32 *th)
+{
+	int freqM;
+	u32 sampling_time;
+
+	/* Retrieve the number of periods to sample */
+	sampling_time = (readl_relaxed(sensor->base + DTS_CFGR1_OFFSET) &
+			TS1_SMP_TIME_MASK) >> TS1_SMP_TIME_POS;
+
+	/* Figure out the CLK_PTAT frequency for a given temperature */
+	freqM = ((temp - sensor->t0) * sensor->ramp_coeff)
+		 + sensor->fmt0;
+
+	dev_dbg(sensor->dev, "%s: freqM for threshold = %d Hz",
+		__func__, freqM);
+
+	/* Figure out the threshold sample number */
+	*th = clk_get_rate(sensor->clk);
+	if (!*th)
+		return -EINVAL;
+
+	*th = *th / freqM;
+
+	*th *= sampling_time;
+
+	return 0;
+}
+
+static int stm_thermal_set_threshold(struct stm_thermal_sensor *sensor)
+{
+	u32 value, th;
+	int ret;
+
+	value = readl_relaxed(sensor->base + DTS_ITR1_OFFSET);
+
+	/* Erase threshold content */
+	value &= ~(TS1_LITTHD_MASK | TS1_HITTHD_MASK);
+
+	/* Retrieve the sample threshold number th for a given temperature */
+	ret = stm_thermal_calculate_threshold(sensor, sensor->high_temp, &th);
+	if (ret)
+		return ret;
+
+	value |= th & TS1_LITTHD_MASK;
+
+	if (sensor->low_temp_enabled) {
+		/* Retrieve the sample threshold */
+		ret = stm_thermal_calculate_threshold(sensor, sensor->low_temp,
+						      &th);
+		if (ret)
+			return ret;
+
+		value |= (TS1_HITTHD_MASK  & (th << TS1_HITTHD_POS));
+	}
+
+	/* Write value on the Low interrupt threshold */
+	writel_relaxed(value, sensor->base + DTS_ITR1_OFFSET);
+
+	return 0;
+}
+
+/* Disable temperature interrupt */
+static int stm_disable_irq(struct stm_thermal_sensor *sensor)
+{
+	u32 value;
+
+	/* Disable IT generation for low and high thresholds */
+	value = readl_relaxed(sensor->base + DTS_ITENR_OFFSET);
+	writel_relaxed(value & ~(LOW_THRESHOLD | HIGH_THRESHOLD),
+		       sensor->base + DTS_ITENR_OFFSET);
+
+	dev_dbg(sensor->dev, "%s: IT disabled on sensor side", __func__);
+
+	return 0;
+}
+
+/* Enable temperature interrupt */
+static int stm_enable_irq(struct stm_thermal_sensor *sensor)
+{
+	u32 value;
+
+	/*
+	 * Code below enables High temperature threshold using a low threshold
+	 * sampling value
+	 */
+
+	/* Make sure LOW_THRESHOLD IT is clear before enabling */
+	writel_relaxed(LOW_THRESHOLD, sensor->base + DTS_CIFR_OFFSET);
+
+	/* Enable IT generation for low threshold */
+	value = readl_relaxed(sensor->base + DTS_ITENR_OFFSET);
+	value |= LOW_THRESHOLD;
+
+	/* Enable the low temperature threshold if needed */
+	if (sensor->low_temp_enabled) {
+		/* Make sure HIGH_THRESHOLD IT is clear before enabling */
+		writel_relaxed(HIGH_THRESHOLD, sensor->base + DTS_CIFR_OFFSET);
+
+		/* Enable IT generation for high threshold */
+		value |= HIGH_THRESHOLD;
+	}
+
+	/* Enable thresholds */
+	writel_relaxed(value, sensor->base + DTS_ITENR_OFFSET);
+
+	dev_dbg(sensor->dev, "%s: IT enabled on sensor side", __func__);
+
+	return 0;
+}
+
+static int stm_thermal_update_threshold(struct stm_thermal_sensor *sensor)
+{
+	int ret;
+
+	sensor->mode = THERMAL_DEVICE_DISABLED;
+
+	ret = stm_sensor_power_off(sensor);
+	if (ret)
+		return ret;
+
+	ret = stm_disable_irq(sensor);
+	if (ret)
+		return ret;
+
+	ret = stm_thermal_set_threshold(sensor);
+	if (ret)
+		return ret;
+
+	ret = stm_enable_irq(sensor);
+	if (ret)
+		return ret;
+
+	ret = stm_sensor_power_on(sensor);
+	if (ret)
+		return ret;
+
+	sensor->mode = THERMAL_DEVICE_ENABLED;
+
+	return 0;
+}
+
+/* Callback to get temperature from HW */
+static int stm_thermal_get_temp(void *data, int *temp)
+{
+	struct stm_thermal_sensor *sensor = data;
+	u32 sampling_time;
+	int freqM, ret;
+
+	if (sensor->mode != THERMAL_DEVICE_ENABLED)
+		return -EAGAIN;
+
+	/* Retrieve the number of samples */
+	ret = readl_poll_timeout(sensor->base + DTS_DR_OFFSET, freqM,
+				 (freqM & TS1_MFREQ_MASK), STARTUP_TIME,
+				 POLL_TIMEOUT);
+
+	if (ret)
+		return ret;
+
+	if (!freqM)
+		return -ENODATA;
+
+	/* Retrieve the number of periods sampled */
+	sampling_time = (readl_relaxed(sensor->base + DTS_CFGR1_OFFSET) &
+			TS1_SMP_TIME_MASK) >> TS1_SMP_TIME_POS;
+
+	/* Figure out the number of samples per period */
+	freqM /= sampling_time;
+
+	/* Figure out the CLK_PTAT frequency */
+	freqM = clk_get_rate(sensor->clk) / freqM;
+	if (!freqM)
+		return -EINVAL;
+
+	dev_dbg(sensor->dev, "%s: freqM=%d\n", __func__, freqM);
+
+	/* Figure out the temperature in mili celsius */
+	*temp = mcelsius(sensor->t0 + ((freqM - sensor->fmt0) /
+			 sensor->ramp_coeff));
+
+	dev_dbg(sensor->dev, "%s: temperature = %d millicelsius",
+		__func__, *temp);
+
+	/* Update thresholds */
+	if (sensor->num_trips > 1) {
+		/* Update alarm threshold value to next higher trip point */
+		if (sensor->high_temp == sensor->temp_passive &&
+		    celsius(*temp) >= sensor->temp_passive) {
+			sensor->high_temp = sensor->temp_critical;
+			sensor->low_temp = sensor->temp_passive;
+			sensor->low_temp_enabled = true;
+			ret = stm_thermal_update_threshold(sensor);
+			if (ret)
+				return ret;
+		}
+
+		if (sensor->high_temp == sensor->temp_critical &&
+		    celsius(*temp) < sensor->temp_passive) {
+			sensor->high_temp = sensor->temp_passive;
+			sensor->low_temp_enabled = false;
+			ret = stm_thermal_update_threshold(sensor);
+			if (ret)
+				return ret;
+		}
+
+		/*
+		 * Re-enable alarm IRQ if temperature below critical
+		 * temperature
+		 */
+		if (!sensor->irq_enabled &&
+		    (celsius(*temp) < sensor->temp_critical)) {
+			sensor->irq_enabled = true;
+			enable_irq(sensor->irq);
+		}
+	}
+
+	return 0;
+}
+
+/* Registers DTS irq to be visible by GIC */
+static int stm_register_irq(struct stm_thermal_sensor *sensor)
+{
+	struct device *dev = sensor->dev;
+	struct platform_device *pdev = to_platform_device(dev);
+	int ret;
+
+	sensor->irq = platform_get_irq(pdev, 0);
+	if (sensor->irq < 0) {
+		dev_err(dev, "%s: Unable to find IRQ\n", __func__);
+		return sensor->irq;
+	}
+
+	ret = devm_request_threaded_irq(dev, sensor->irq,
+					stm_thermal_alarm_irq,
+					stm_thermal_alarm_irq_thread,
+					IRQF_ONESHOT,
+					dev->driver->name, sensor);
+	if (ret) {
+		dev_err(dev, "%s: Failed to register IRQ %d\n", __func__,
+			sensor->irq);
+		return ret;
+	}
+
+	sensor->irq_enabled = true;
+
+	dev_dbg(dev, "%s: thermal IRQ registered", __func__);
+
+	return 0;
+}
+
+static int stm_thermal_sensor_off(struct stm_thermal_sensor *sensor)
+{
+	int ret;
+
+	ret = stm_sensor_power_off(sensor);
+	if (ret)
+		return ret;
+
+	clk_disable_unprepare(sensor->clk);
+
+	return 0;
+}
+
+static int stm_thermal_prepare(struct stm_thermal_sensor *sensor)
+{
+	int ret;
+	struct device *dev = sensor->dev;
+
+	ret = clk_prepare_enable(sensor->clk);
+	if (ret)
+		return ret;
+
+	ret = stm_thermal_calibration(sensor);
+	if (ret)
+		goto thermal_unprepare;
+
+	/* Set threshold(s) for IRQ */
+	ret = stm_thermal_set_threshold(sensor);
+	if (ret)
+		goto thermal_unprepare;
+
+	ret = stm_enable_irq(sensor);
+	if (ret)
+		goto thermal_unprepare;
+
+	ret = stm_sensor_power_on(sensor);
+	if (ret) {
+		dev_err(dev, "%s: failed to power on sensor\n", __func__);
+		goto irq_disable;
+	}
+
+	return 0;
+
+irq_disable:
+	stm_disable_irq(sensor);
+
+thermal_unprepare:
+	clk_disable_unprepare(sensor->clk);
+
+	return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int stm_thermal_suspend(struct device *dev)
+{
+	int ret;
+	struct platform_device *pdev = to_platform_device(dev);
+	struct stm_thermal_sensor *sensor = platform_get_drvdata(pdev);
+
+	ret = stm_thermal_sensor_off(sensor);
+	if (ret)
+		return ret;
+
+	sensor->mode = THERMAL_DEVICE_DISABLED;
+
+	return 0;
+}
+
+static int stm_thermal_resume(struct device *dev)
+{
+	int ret;
+	struct platform_device *pdev = to_platform_device(dev);
+	struct stm_thermal_sensor *sensor = platform_get_drvdata(pdev);
+
+	ret = stm_thermal_prepare(sensor);
+	if (ret)
+		return ret;
+
+	sensor->mode = THERMAL_DEVICE_ENABLED;
+
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+SIMPLE_DEV_PM_OPS(stm_thermal_pm_ops, stm_thermal_suspend, stm_thermal_resume);
+
+static const struct thermal_zone_of_device_ops stm_tz_ops = {
+	.get_temp	= stm_thermal_get_temp,
+};
+
+static const struct of_device_id stm_thermal_of_match[] = {
+		{ .compatible = "st,stm32-thermal"},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, stm_thermal_of_match);
+
+static int stm_thermal_probe(struct platform_device *pdev)
+{
+	struct stm_thermal_sensor *sensor;
+	struct resource *res;
+	const struct thermal_trip *trip;
+	void __iomem *base;
+	int ret, i;
+
+	if (!pdev->dev.of_node) {
+		dev_err(&pdev->dev, "%s: device tree node not found\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	sensor = devm_kzalloc(&pdev->dev, sizeof(*sensor), GFP_KERNEL);
+	if (!sensor)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, sensor);
+
+	sensor->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	/* Populate sensor */
+	sensor->base = base;
+
+	ret = stm_thermal_read_factory_settings(sensor);
+	if (ret)
+		return ret;
+
+	sensor->clk = devm_clk_get(&pdev->dev, "pclk");
+	if (IS_ERR(sensor->clk)) {
+		dev_err(&pdev->dev, "%s: failed to fetch PCLK clock\n",
+			__func__);
+		return PTR_ERR(sensor->clk);
+	}
+
+	/* Register IRQ into GIC */
+	ret = stm_register_irq(sensor);
+	if (ret)
+		return ret;
+
+	sensor->th_dev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0,
+							      sensor,
+							      &stm_tz_ops);
+
+	if (IS_ERR(sensor->th_dev)) {
+		dev_err(&pdev->dev, "%s: thermal zone sensor registering KO\n",
+			__func__);
+		ret = PTR_ERR(sensor->th_dev);
+		return ret;
+	}
+
+	if (!sensor->th_dev->ops->get_crit_temp) {
+		/* Critical point must be provided */
+		ret = -EINVAL;
+		goto err_tz;
+	}
+
+	ret = sensor->th_dev->ops->get_crit_temp(sensor->th_dev,
+			&sensor->temp_critical);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Not able to read critical_temp: %d\n", ret);
+		goto err_tz;
+	}
+
+	sensor->temp_critical = celsius(sensor->temp_critical);
+
+	/* Set thresholds for IRQ */
+	sensor->high_temp = sensor->temp_critical;
+
+	trip = of_thermal_get_trip_points(sensor->th_dev);
+	sensor->num_trips = of_thermal_get_ntrips(sensor->th_dev);
+
+	/* Find out passive temperature if it exists */
+	for (i = (sensor->num_trips - 1); i >= 0;  i--) {
+		if (trip[i].type == THERMAL_TRIP_PASSIVE) {
+			sensor->temp_passive = celsius(trip[i].temperature);
+			/* Update high temperature threshold */
+			sensor->high_temp = sensor->temp_passive;
+			}
+	}
+
+	/*
+	 * Ensure low_temp_enabled flag is disabled.
+	 * By disabling low_temp_enabled, low threshold IT will not be
+	 * configured neither enabled because it is not needed as high
+	 * threshold is set on the lowest temperature trip point after
+	 * probe.
+	 */
+	sensor->low_temp_enabled = false;
+
+	/* Configure and enable HW sensor */
+	ret = stm_thermal_prepare(sensor);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Not able to enable sensor: %d\n", ret);
+		goto err_tz;
+	}
+
+	/*
+	 * Thermal_zone doesn't enable hwmon as default,
+	 * enable it here
+	 */
+	sensor->th_dev->tzp->no_hwmon = false;
+	ret = thermal_add_hwmon_sysfs(sensor->th_dev);
+	if (ret)
+		goto err_tz;
+
+	sensor->mode = THERMAL_DEVICE_ENABLED;
+
+	dev_info(&pdev->dev, "%s: Driver initialized successfully\n",
+		 __func__);
+
+	return 0;
+
+err_tz:
+	thermal_zone_of_sensor_unregister(&pdev->dev, sensor->th_dev);
+	return ret;
+}
+
+static int stm_thermal_remove(struct platform_device *pdev)
+{
+	struct stm_thermal_sensor *sensor = platform_get_drvdata(pdev);
+
+	stm_thermal_sensor_off(sensor);
+	thermal_remove_hwmon_sysfs(sensor->th_dev);
+	thermal_zone_of_sensor_unregister(&pdev->dev, sensor->th_dev);
+
+	return 0;
+}
+
+static struct platform_driver stm_thermal_driver = {
+	.driver = {
+		.name	= "stm_thermal",
+		.pm     = &stm_thermal_pm_ops,
+		.of_match_table = stm_thermal_of_match,
+	},
+	.probe		= stm_thermal_probe,
+	.remove		= stm_thermal_remove,
+};
+module_platform_driver(stm_thermal_driver);
+
+MODULE_DESCRIPTION("STMicroelectronics STM32 Thermal Sensor Driver");
+MODULE_AUTHOR("David Hernandez Sanchez <david.hernandezsanchez@st.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:stm_thermal");