thermal/drivers/renesas/rzg3s: Add thermal driver for the Renesas RZ/G3S SoC

The Renesas RZ/G3S SoC features a Thermal Sensor Unit (TSU) that reports
the junction temperature. The temperature is reported through a dedicated
ADC channel. Add a driver for the Renesas RZ/G3S TSU.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20250810122125.792966-3-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

MAINTAINERS

@@ -21541,6 +21541,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/potentiometer/renesas,x9250.yaml
 F:	drivers/iio/potentiometer/x9250.c
 
+RENESAS RZ/G3S THERMAL SENSOR UNIT DRIVER
+M:	Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
+L:	linux-pm@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/thermal/renesas,r9a08g045-tsu.yaml
+F:	drivers/thermal/renesas/rzg3s_thermal.c
+
 RESET CONTROLLER FRAMEWORK
 M:	Philipp Zabel <p.zabel@pengutronix.de>
 S:	Maintained

drivers/thermal/renesas/Kconfig

@@ -26,3 +26,11 @@ config RZG2L_THERMAL
 	help
 	  Enable this to plug the RZ/G2L thermal sensor driver into the Linux
 	  thermal framework.
+
+config RZG3S_THERMAL
+	tristate "Renesas RZ/G3S thermal driver"
+	depends on ARCH_R9A08G045 || COMPILE_TEST
+	depends on OF && IIO && RZG2L_ADC
+	help
+	  Enable this to plug the RZ/G3S thermal sensor driver into the Linux
+	  thermal framework.

drivers/thermal/renesas/Makefile

@@ -3,3 +3,4 @@
 obj-$(CONFIG_RCAR_GEN3_THERMAL)	+= rcar_gen3_thermal.o
 obj-$(CONFIG_RCAR_THERMAL)	+= rcar_thermal.o
 obj-$(CONFIG_RZG2L_THERMAL)	+= rzg2l_thermal.o
+obj-$(CONFIG_RZG3S_THERMAL)	+= rzg3s_thermal.o

drivers/thermal/renesas/rzg3s_thermal.c

@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Renesas RZ/G3S TSU Thermal Sensor Driver
+ *
+ * Copyright (C) 2024 Renesas Electronics Corporation
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/iio/consumer.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/reset.h>
+#include <linux/thermal.h>
+#include <linux/units.h>
+
+#include "../thermal_hwmon.h"
+
+#define TSU_SM			0x0
+#define TSU_SM_EN		BIT(0)
+#define TSU_SM_OE		BIT(1)
+#define OTPTSUTRIM_REG(n)	(0x18 + (n) * 0x4)
+#define OTPTSUTRIM_EN_MASK	BIT(31)
+#define OTPTSUTRIM_MASK		GENMASK(11, 0)
+
+#define TSU_READ_STEPS		8
+
+/* Default calibration values, if FUSE values are missing. */
+#define SW_CALIB0_VAL		1297
+#define SW_CALIB1_VAL		751
+
+#define MCELSIUS(temp)		((temp) * MILLIDEGREE_PER_DEGREE)
+
+/**
+ * struct rzg3s_thermal_priv - RZ/G3S thermal private data structure
+ * @base: TSU base address
+ * @dev: device pointer
+ * @tz: thermal zone pointer
+ * @rstc: reset control
+ * @channel: IIO channel to read the TSU
+ * @mode: current device mode
+ * @calib0: calibration value
+ * @calib1: calibration value
+ */
+struct rzg3s_thermal_priv {
+	void __iomem *base;
+	struct device *dev;
+	struct thermal_zone_device *tz;
+	struct reset_control *rstc;
+	struct iio_channel *channel;
+	enum thermal_device_mode mode;
+	u16 calib0;
+	u16 calib1;
+};
+
+static int rzg3s_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct rzg3s_thermal_priv *priv = thermal_zone_device_priv(tz);
+	int ts_code_ave = 0;
+
+	if (priv->mode != THERMAL_DEVICE_ENABLED)
+		return -EAGAIN;
+
+	for (u8 i = 0; i < TSU_READ_STEPS; i++) {
+		int ret, val;
+
+		ret = iio_read_channel_raw(priv->channel, &val);
+		if (ret < 0)
+			return ret;
+
+		ts_code_ave += val;
+		/*
+		 * According to the HW manual (Rev.1.10, section 40.4.4 Procedure for Measuring
+		 * the Temperature) we need to wait here at leat 3us.
+		 */
+		usleep_range(5, 10);
+	}
+
+	ts_code_ave = DIV_ROUND_CLOSEST(MCELSIUS(ts_code_ave), TSU_READ_STEPS);
+
+	/*
+	 * According to the HW manual (Rev.1.10, section 40.4.4 Procedure for Measuring the
+	 * Temperature) the computation formula is as follows:
+	 *
+	 * Tj = (ts_code_ave - priv->calib1) * 165 / (priv->calib0 - priv->calib1) - 40
+	 *
+	 * Convert everything to milli Celsius before applying the formula to avoid
+	 * losing precision.
+	 */
+
+	*temp = div_s64((s64)(ts_code_ave - MCELSIUS(priv->calib1)) * MCELSIUS(165),
+			MCELSIUS(priv->calib0 - priv->calib1)) - MCELSIUS(40);
+
+	/* Report it in milli degrees Celsius and round it up to 0.5 degrees Celsius. */
+	*temp = roundup(*temp, 500);
+
+	return 0;
+}
+
+static void rzg3s_thermal_set_mode(struct rzg3s_thermal_priv *priv,
+				   enum thermal_device_mode mode)
+{
+	struct device *dev = priv->dev;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret)
+		return;
+
+	if (mode == THERMAL_DEVICE_DISABLED) {
+		writel(0, priv->base + TSU_SM);
+	} else {
+		writel(TSU_SM_EN, priv->base + TSU_SM);
+		/*
+		 * According to the HW manual (Rev.1.10, section 40.4.1 Procedure for
+		 * Starting the TSU) we need to wait here 30us or more.
+		 */
+		usleep_range(30, 40);
+
+		writel(TSU_SM_OE | TSU_SM_EN, priv->base + TSU_SM);
+		/*
+		 * According to the HW manual (Rev.1.10, section 40.4.1 Procedure for
+		 * Starting the TSU) we need to wait here 50us or more.
+		 */
+		usleep_range(50, 60);
+	}
+
+	pm_runtime_put_autosuspend(dev);
+}
+
+static int rzg3s_thermal_change_mode(struct thermal_zone_device *tz,
+				     enum thermal_device_mode mode)
+{
+	struct rzg3s_thermal_priv *priv = thermal_zone_device_priv(tz);
+
+	if (priv->mode == mode)
+		return 0;
+
+	rzg3s_thermal_set_mode(priv, mode);
+	priv->mode = mode;
+
+	return 0;
+}
+
+static const struct thermal_zone_device_ops rzg3s_tz_of_ops = {
+	.get_temp = rzg3s_thermal_get_temp,
+	.change_mode = rzg3s_thermal_change_mode,
+};
+
+static int rzg3s_thermal_read_calib(struct rzg3s_thermal_priv *priv)
+{
+	struct device *dev = priv->dev;
+	u32 val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret)
+		return ret;
+
+	val = readl(priv->base + OTPTSUTRIM_REG(0));
+	if (val & OTPTSUTRIM_EN_MASK)
+		priv->calib0 = FIELD_GET(OTPTSUTRIM_MASK, val);
+	else
+		priv->calib0 = SW_CALIB0_VAL;
+
+	val = readl(priv->base + OTPTSUTRIM_REG(1));
+	if (val & OTPTSUTRIM_EN_MASK)
+		priv->calib1 = FIELD_GET(OTPTSUTRIM_MASK, val);
+	else
+		priv->calib1 = SW_CALIB1_VAL;
+
+	pm_runtime_put_autosuspend(dev);
+
+	return 0;
+}
+
+static int rzg3s_thermal_probe(struct platform_device *pdev)
+{
+	struct rzg3s_thermal_priv *priv;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
+
+	priv->channel = devm_iio_channel_get(dev, "tsu");
+	if (IS_ERR(priv->channel))
+		return dev_err_probe(dev, PTR_ERR(priv->channel), "Failed to get IIO channel!\n");
+
+	priv->rstc = devm_reset_control_get_exclusive_deasserted(dev, NULL);
+	if (IS_ERR(priv->rstc))
+		return dev_err_probe(dev, PTR_ERR(priv->rstc), "Failed to get reset!\n");
+
+	priv->dev = dev;
+	priv->mode = THERMAL_DEVICE_DISABLED;
+	platform_set_drvdata(pdev, priv);
+
+	pm_runtime_set_autosuspend_delay(dev, 300);
+	pm_runtime_use_autosuspend(dev);
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable runtime PM!\n");
+
+	ret = rzg3s_thermal_read_calib(priv);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to read calibration data!\n");
+
+	priv->tz = devm_thermal_of_zone_register(dev, 0, priv, &rzg3s_tz_of_ops);
+	if (IS_ERR(priv->tz))
+		return dev_err_probe(dev, PTR_ERR(priv->tz), "Failed to register thermal zone!\n");
+
+	ret = devm_thermal_add_hwmon_sysfs(dev, priv->tz);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to add hwmon sysfs!\n");
+
+	return 0;
+}
+
+static int rzg3s_thermal_suspend(struct device *dev)
+{
+	struct rzg3s_thermal_priv *priv = dev_get_drvdata(dev);
+
+	rzg3s_thermal_set_mode(priv, THERMAL_DEVICE_DISABLED);
+
+	return reset_control_assert(priv->rstc);
+}
+
+static int rzg3s_thermal_resume(struct device *dev)
+{
+	struct rzg3s_thermal_priv *priv = dev_get_drvdata(dev);
+	int ret;
+
+	ret = reset_control_deassert(priv->rstc);
+	if (ret)
+		return ret;
+
+	if (priv->mode != THERMAL_DEVICE_DISABLED)
+		rzg3s_thermal_set_mode(priv, priv->mode);
+
+	return 0;
+}
+
+static const struct dev_pm_ops rzg3s_thermal_pm_ops = {
+	SYSTEM_SLEEP_PM_OPS(rzg3s_thermal_suspend, rzg3s_thermal_resume)
+};
+
+static const struct of_device_id rzg3s_thermal_dt_ids[] = {
+	{ .compatible = "renesas,r9a08g045-tsu" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rzg3s_thermal_dt_ids);
+
+static struct platform_driver rzg3s_thermal_driver = {
+	.driver = {
+		.name = "rzg3s-thermal",
+		.of_match_table = rzg3s_thermal_dt_ids,
+		.pm = pm_ptr(&rzg3s_thermal_pm_ops),
+	},
+	.probe = rzg3s_thermal_probe,
+};
+module_platform_driver(rzg3s_thermal_driver);
+
+MODULE_DESCRIPTION("Renesas RZ/G3S Thermal Sensor Unit Driver");
+MODULE_AUTHOR("Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>");
+MODULE_LICENSE("GPL");