thermal/drivers/qcom: Add support for Qualcomm MBG thermal monitoring

Add a driver for the Qualcomm MBG (Master Bandgap) thermal monitoring
device. It monitors PMIC die temperature in hardware and raises an
interrupt when a programmed threshold is crossed.

MBG hardware supports two upper-threshold levels. Currently, only the
level-1 threshold is supported by the driver.

Temperature is read from the associated ADC channel, and when a level-1
upper-threshold violation occurs, the hardware generates an interrupt
over SPMI. The driver notifies the thermal framework accordingly.

Signed-off-by: Satya Priya Kakitapalli <quic_skakitap@quicinc.com>
Co-developed-by: Sachin Gupta <sachin.gupta@oss.qualcomm.com>
Signed-off-by: Sachin Gupta <sachin.gupta@oss.qualcomm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@kernel.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260722-spmi-mbg-driver-v3-2-ef73064f2789@oss.qualcomm.com

drivers/thermal/qcom/Kconfig

@@ -21,6 +21,20 @@ config QCOM_SPMI_ADC_TM5
 	  Thermal client sets threshold temperature for both warm and cool and
 	  gets updated when a threshold is reached.
 
+config QCOM_SPMI_MBG_TM
+	tristate "Qualcomm SPMI PMIC MBG Temperature monitor"
+	depends on QCOM_SPMI_ADC5_GEN3
+	select REGMAP_SPMI
+	help
+	  This enables Qualcomm PMIC MBG (Master Bandgap) thermal monitor.
+
+	  The MBG block monitors PMIC die temperature in hardware and raises an
+	  interrupt when the programmed threshold is crossed.
+
+	  Temperature is read from the associated ADC channel, and threshold
+	  interrupts are forwarded to the thermal framework as trip-violation
+	  events. Current support handles a single LVL1 upper (hot) trip.
+
 config QCOM_SPMI_TEMP_ALARM
 	tristate "Qualcomm SPMI PMIC Temperature Alarm"
 	depends on OF && SPMI && IIO

drivers/thermal/qcom/Makefile

@@ -4,5 +4,6 @@ obj-$(CONFIG_QCOM_TSENS)	+= qcom_tsens.o
 qcom_tsens-y			+= tsens.o tsens-v2.o tsens-v1.o tsens-v0_1.o \
 				   tsens-8960.o
 obj-$(CONFIG_QCOM_SPMI_ADC_TM5)	+= qcom-spmi-adc-tm5.o
+obj-$(CONFIG_QCOM_SPMI_MBG_TM) += qcom-spmi-mbg-tm.o
 obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)	+= qcom-spmi-temp-alarm.o
 obj-$(CONFIG_QCOM_LMH)		+= lmh.o

drivers/thermal/qcom/qcom-spmi-mbg-tm.c

@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/thermal.h>
+#include <linux/iio/consumer.h>
+
+#define MBG_TEMP_MON2_FAULT_STATUS	0x50
+
+#define MON_FAULT_STATUS_MASK		GENMASK(7, 4)
+#define MON_FAULT_LVL1_UPR		0x5
+
+#define MON2_LVL1_UP_THRESH		0x59
+
+#define MBG_TEMP_MON2_MISC_CFG		0x5f
+#define MON2_UP_THRESH_EN		BIT(1)
+
+#define MBG_TEMP_STEP_MV		8
+#define MBG_TEMP_DEFAULT_TEMP_MV	600
+#define MBG_TEMP_CONSTANT		1000
+#define MBG_MIN_TRIP_TEMP		25000
+#define MBG_MAX_SUPPORTED_TEMP		160000
+
+/**
+ * struct mbg_tm_chip - MBG thermal monitor device data.
+ * @map: regmap for accessing MBG thermal registers.
+ * @dev: mbg_tm_chip device.
+ * @tz_dev: thermal zone device registered with the thermal framework.
+ * @lock: mbg_tm_chip lock for set trip temperature.
+ * @base: base register offset for this MBG instance
+ * @irq: interrupt line used to signal threshold events
+ * @last_temp: last measured temperature.
+ * @last_thres_crossed: indicates whether the last interrupt crossed a threshold
+ * @adc: IIO ADC channel used for temperature sensing
+ */
+struct mbg_tm_chip {
+	struct regmap			*map;
+	struct device			*dev;
+	struct thermal_zone_device	*tz_dev;
+	struct mutex                    lock;
+	unsigned int			base;
+	int				irq;
+	int				last_temp;
+	bool				last_thres_crossed;
+	struct iio_channel		*adc;
+};
+
+/**
+ * struct mbg_map_table - temperature to voltage mapping entry
+ * @min_temp: minimum temperature supported by this mapping entry
+ * @vtemp0: reference voltage or ADC code corresponding to the temperature
+ * @tc: temperature coefficient used for conversion calculations
+ */
+struct mbg_map_table {
+	int min_temp;
+	int vtemp0;
+	int tc;
+};
+
+static const struct mbg_map_table map_table[] = {
+	{ -60000, 4337, 1967 },
+	{ -40000, 4731, 1964 },
+	{ -20000, 5124, 1957 },
+	{ 0,      5515, 1949 },
+	{ 20000,  5905, 1940 },
+	{ 40000,  6293, 1930 },
+	{ 60000,  6679, 1921 },
+	{ 80000,  7064, 1910 },
+	{ 100000, 7446, 1896 },
+	{ 120000, 7825, 1878 },
+	{ 140000, 8201, 1859 },
+};
+
+static int mbg_tm_get_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct mbg_tm_chip *chip = thermal_zone_device_priv(tz);
+	int ret, milli_celsius;
+
+	scoped_guard(mutex, &chip->lock) {
+		if (chip->last_thres_crossed) {
+			dev_dbg(chip->dev, "last_temp: %d\n", chip->last_temp);
+			chip->last_thres_crossed = false;
+			*temp = chip->last_temp;
+			return 0;
+		}
+	}
+
+	ret = iio_read_channel_processed(chip->adc, &milli_celsius);
+	if (ret < 0) {
+		dev_err(chip->dev, "Failed to read iio channel with %d\n", ret);
+		return ret;
+	}
+
+	*temp = milli_celsius;
+
+	return 0;
+}
+
+static int temp_to_vtemp_mv(int temp)
+{
+	int idx, vtemp, tc = 0, t0 = 0, vtemp0 = 0;
+
+	for (idx = 0; idx < ARRAY_SIZE(map_table); idx++)
+		if (temp >= map_table[idx].min_temp &&
+		    temp < (map_table[idx].min_temp + 20000)) {
+			tc = map_table[idx].tc;
+			t0 = map_table[idx].min_temp;
+			vtemp0 = map_table[idx].vtemp0;
+			break;
+		}
+
+	/*
+	 * Formula to calculate vtemp(mV) from a given temp
+	 * vtemp = (temp - minT) * tc + vtemp0
+	 * tc, t0 and vtemp0 values are mentioned in the map_table array.
+	 */
+	vtemp = ((temp - t0) * tc + vtemp0 * 100000) / 1000000;
+
+	/* step size is 8mV */
+	return abs(vtemp - MBG_TEMP_DEFAULT_TEMP_MV) / MBG_TEMP_STEP_MV;
+}
+
+static int mbg_tm_set_trip_temp(struct thermal_zone_device *tz, int low_temp,
+				int temp)
+{
+	struct mbg_tm_chip *chip = thermal_zone_device_priv(tz);
+	int ret = 0;
+
+	guard(mutex)(&chip->lock);
+
+	/* The HW has a limitation that the trip set must be above 25C */
+	if (temp > MBG_MIN_TRIP_TEMP && temp < MBG_MAX_SUPPORTED_TEMP) {
+		ret = regmap_write(chip->map, chip->base + MON2_LVL1_UP_THRESH,
+				   temp_to_vtemp_mv(temp));
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_set_bits(chip->map, chip->base + MBG_TEMP_MON2_MISC_CFG,
+				      MON2_UP_THRESH_EN);
+		if (ret < 0)
+			return ret;
+	} else {
+		dev_err(chip->dev, "Set trip b/w 25C and 160C\n");
+		ret = regmap_clear_bits(chip->map, chip->base + MBG_TEMP_MON2_MISC_CFG,
+					MON2_UP_THRESH_EN);
+		return -ERANGE;
+	}
+
+	/*
+	 * Configure the last_temp one degree higher, to ensure the
+	 * violated temp is returned to thermal framework when it reads
+	 * temperature for the first time after the violation happens.
+	 * This is needed to account for the inaccuracy in the conversion
+	 * formula used which leads to the thermal framework setting back
+	 * the same thresholds in case the temperature it reads does not
+	 * show violation.
+	 */
+	chip->last_temp = temp + MBG_TEMP_CONSTANT;
+
+	return ret;
+}
+
+static const struct thermal_zone_device_ops mbg_tm_ops = {
+	.get_temp = mbg_tm_get_temp,
+	.set_trips = mbg_tm_set_trip_temp,
+};
+
+static irqreturn_t mbg_tm_isr(int irq, void *data)
+{
+	struct mbg_tm_chip *chip = data;
+	int ret, val;
+
+	scoped_guard(mutex, &chip->lock) {
+		ret = regmap_read(chip->map, chip->base + MBG_TEMP_MON2_FAULT_STATUS, &val);
+		if (ret < 0)
+			return IRQ_HANDLED;
+		if (FIELD_GET(MON_FAULT_STATUS_MASK, val) == MON_FAULT_LVL1_UPR)
+			chip->last_thres_crossed = true;
+	}
+
+	if (FIELD_GET(MON_FAULT_STATUS_MASK, val) == MON_FAULT_LVL1_UPR) {
+		dev_dbg(chip->dev, "Notifying Thermal, fault status=%d\n", val);
+		thermal_zone_device_update(chip->tz_dev, THERMAL_TRIP_VIOLATED);
+	} else {
+		dev_dbg(chip->dev, "Lvl1 upper threshold not violated, ignoring interrupt\n");
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int mbg_tm_probe(struct platform_device *pdev)
+{
+	struct mbg_tm_chip *chip;
+	struct device_node *node = pdev->dev.of_node;
+	u32 res;
+	int ret;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->dev = &pdev->dev;
+
+	mutex_init(&chip->lock);
+
+	chip->map = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!chip->map)
+		return -ENXIO;
+
+	ret = device_property_read_u32(chip->dev, "reg", &res);
+	if (ret < 0)
+		return dev_err_probe(chip->dev, ret, "Couldn't read reg property\n");
+
+	chip->base = res;
+
+	chip->irq = platform_get_irq(pdev, 0);
+	if (chip->irq < 0)
+		return dev_err_probe(chip->dev, chip->irq, "Failed to get irq\n");
+
+	chip->adc = devm_iio_channel_get(&pdev->dev, "thermal");
+	if (IS_ERR(chip->adc))
+		return dev_err_probe(chip->dev, PTR_ERR(chip->adc), "Failed to get adc channel\n");
+
+	chip->tz_dev = devm_thermal_of_zone_register(chip->dev, 0, chip, &mbg_tm_ops);
+	if (IS_ERR(chip->tz_dev))
+		return dev_err_probe(chip->dev, PTR_ERR(chip->tz_dev),
+				     "Failed to register sensor\n");
+
+	return devm_request_threaded_irq(&pdev->dev, chip->irq, NULL, mbg_tm_isr, IRQF_ONESHOT,
+					 node->name, chip);
+}
+
+static const struct of_device_id mbg_tm_match_table[] = {
+	{ .compatible = "qcom,pm8775-mbg-tm" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mbg_tm_match_table);
+
+static struct platform_driver mbg_tm_driver = {
+	.driver = {
+		.name = "qcom-spmi-mbg-tm",
+		.of_match_table = mbg_tm_match_table,
+	},
+	.probe = mbg_tm_probe,
+};
+module_platform_driver(mbg_tm_driver);
+
+MODULE_DESCRIPTION("PMIC MBG Temperature monitor driver");
+MODULE_LICENSE("GPL");