thermal: Add QPNP PMIC temperature alarm driver

Add support for the temperature alarm peripheral found inside
Qualcomm plug-and-play (QPNP) PMIC chips. The temperature alarm
peripheral outputs a pulse on an interrupt line whenever the
thermal over temperature stage value changes.

Register a thermal sensor. The temperature reported by this thermal
sensor device should reflect the actual PMIC die temperature if an
ADC is present on the given PMIC. If no ADC is present, then the
reported temperature should be estimated from the over temperature
stage value.

Cc: David Collins <collinsd@codeaurora.org>
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

Documentation/devicetree/bindings/thermal/qcom-spmi-temp-alarm.txt

@@ -0,0 +1,57 @@
+Qualcomm QPNP PMIC Temperature Alarm
+
+QPNP temperature alarm peripherals are found inside of Qualcomm PMIC chips
+that utilize the Qualcomm SPMI implementation. These peripherals provide an
+interrupt signal and status register to identify high PMIC die temperature.
+
+Required properties:
+- compatible:      Should contain "qcom,spmi-temp-alarm".
+- reg:             Specifies the SPMI address and length of the controller's
+                   registers.
+- interrupts:      PMIC temperature alarm interrupt.
+- #thermal-sensor-cells: Should be 0. See thermal.txt for a description.
+
+Optional properties:
+- io-channels:     Should contain IIO channel specifier for the ADC channel,
+                   which report chip die temperature.
+- io-channel-names: Should contain "thermal".
+
+Example:
+
+	pm8941_temp: thermal-alarm@2400 {
+		compatible = "qcom,spmi-temp-alarm";
+		reg = <0x2400 0x100>;
+		interrupts = <0 0x24 0 IRQ_TYPE_EDGE_RISING>;
+		#thermal-sensor-cells = <0>;
+
+		io-channels = <&pm8941_vadc VADC_DIE_TEMP>;
+		io-channel-names = "thermal";
+	};
+
+	thermal-zones {
+		pm8941 {
+			polling-delay-passive = <250>;
+			polling-delay = <1000>;
+
+			thermal-sensors = <&pm8941_temp>;
+
+			trips {
+				passive {
+					temperature = <1050000>;
+					hysteresis = <2000>;
+					type = "passive";
+				};
+				alert {
+					temperature = <125000>;
+					hysteresis = <2000>;
+					type = "hot";
+				};
+				crit {
+					temperature = <145000>;
+					hysteresis = <2000>;
+					type = "critical";
+				};
+			};
+		};
+	};
+

drivers/thermal/Kconfig

@@ -299,4 +299,15 @@ depends on ARCH_STI && OF
 source "drivers/thermal/st/Kconfig"
 endmenu
 
+config QCOM_SPMI_TEMP_ALARM
+	tristate "Qualcomm SPMI PMIC Temperature Alarm"
+	depends on OF && SPMI && IIO
+	select REGMAP_SPMI
+	help
+	  This enables a thermal sysfs driver for Qualcomm plug-and-play (QPNP)
+	  PMIC devices. It shows up in sysfs as a thermal sensor with multiple
+	  trip points. The temperature reported by the thermal sensor reflects the
+	  real time die temperature if an ADC is present or an estimate of the
+	  temperature based upon the over temperature stage value.
+
 endif

drivers/thermal/Makefile

@@ -22,6 +22,7 @@ thermal_sys-$(CONFIG_CPU_THERMAL)	+= cpu_cooling.o
 thermal_sys-$(CONFIG_CLOCK_THERMAL)	+= clock_cooling.o
 
 # platform thermal drivers
+obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)	+= qcom-spmi-temp-alarm.o
 obj-$(CONFIG_SPEAR_THERMAL)	+= spear_thermal.o
 obj-$(CONFIG_ROCKCHIP_THERMAL)	+= rockchip_thermal.o
 obj-$(CONFIG_RCAR_THERMAL)	+= rcar_thermal.o

drivers/thermal/qcom-spmi-temp-alarm.c

@@ -0,0 +1,309 @@
+/*
+ * Copyright (c) 2011-2015, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/iio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/thermal.h>
+
+#define QPNP_TM_REG_TYPE		0x04
+#define QPNP_TM_REG_SUBTYPE		0x05
+#define QPNP_TM_REG_STATUS		0x08
+#define QPNP_TM_REG_SHUTDOWN_CTRL1	0x40
+#define QPNP_TM_REG_ALARM_CTRL		0x46
+
+#define QPNP_TM_TYPE			0x09
+#define QPNP_TM_SUBTYPE			0x08
+
+#define STATUS_STAGE_MASK		0x03
+
+#define SHUTDOWN_CTRL1_THRESHOLD_MASK	0x03
+
+#define ALARM_CTRL_FORCE_ENABLE		0x80
+
+/*
+ * Trip point values based on threshold control
+ * 0 = {105 C, 125 C, 145 C}
+ * 1 = {110 C, 130 C, 150 C}
+ * 2 = {115 C, 135 C, 155 C}
+ * 3 = {120 C, 140 C, 160 C}
+*/
+#define TEMP_STAGE_STEP			20000	/* Stage step: 20.000 C */
+#define TEMP_STAGE_HYSTERESIS		2000
+
+#define TEMP_THRESH_MIN			105000	/* Threshold Min: 105 C */
+#define TEMP_THRESH_STEP		5000	/* Threshold step: 5 C */
+
+#define THRESH_MIN			0
+
+/* Temperature in Milli Celsius reported during stage 0 if no ADC is present */
+#define DEFAULT_TEMP			37000
+
+struct qpnp_tm_chip {
+	struct regmap			*map;
+	struct thermal_zone_device	*tz_dev;
+	long				temp;
+	unsigned int			thresh;
+	unsigned int			stage;
+	unsigned int			prev_stage;
+	unsigned int			base;
+	struct iio_channel		*adc;
+};
+
+static int qpnp_tm_read(struct qpnp_tm_chip *chip, u16 addr, u8 *data)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(chip->map, chip->base + addr, &val);
+	if (ret < 0)
+		return ret;
+
+	*data = val;
+	return 0;
+}
+
+static int qpnp_tm_write(struct qpnp_tm_chip *chip, u16 addr, u8 data)
+{
+	return regmap_write(chip->map, chip->base + addr, data);
+}
+
+/*
+ * This function updates the internal temp value based on the
+ * current thermal stage and threshold as well as the previous stage
+ */
+static int qpnp_tm_update_temp_no_adc(struct qpnp_tm_chip *chip)
+{
+	unsigned int stage;
+	int ret;
+	u8 reg = 0;
+
+	ret = qpnp_tm_read(chip, QPNP_TM_REG_STATUS, &reg);
+	if (ret < 0)
+		return ret;
+
+	stage = reg & STATUS_STAGE_MASK;
+
+	if (stage > chip->stage) {
+		/* increasing stage, use lower bound */
+		chip->temp = (stage - 1) * TEMP_STAGE_STEP +
+			     chip->thresh * TEMP_THRESH_STEP +
+			     TEMP_STAGE_HYSTERESIS + TEMP_THRESH_MIN;
+	} else if (stage < chip->stage) {
+		/* decreasing stage, use upper bound */
+		chip->temp = stage * TEMP_STAGE_STEP +
+			     chip->thresh * TEMP_THRESH_STEP -
+			     TEMP_STAGE_HYSTERESIS + TEMP_THRESH_MIN;
+	}
+
+	chip->stage = stage;
+
+	return 0;
+}
+
+static int qpnp_tm_get_temp(void *data, long *temp)
+{
+	struct qpnp_tm_chip *chip = data;
+	int ret, mili_celsius;
+
+	if (!temp)
+		return -EINVAL;
+
+	if (IS_ERR(chip->adc)) {
+		ret = qpnp_tm_update_temp_no_adc(chip);
+		if (ret < 0)
+			return ret;
+	} else {
+		ret = iio_read_channel_processed(chip->adc, &mili_celsius);
+		if (ret < 0)
+			return ret;
+
+		chip->temp = mili_celsius;
+	}
+
+	*temp = chip->temp < 0 ? 0 : chip->temp;
+
+	return 0;
+}
+
+static const struct thermal_zone_of_device_ops qpnp_tm_sensor_ops = {
+	.get_temp = qpnp_tm_get_temp,
+};
+
+static irqreturn_t qpnp_tm_isr(int irq, void *data)
+{
+	struct qpnp_tm_chip *chip = data;
+
+	thermal_zone_device_update(chip->tz_dev);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * This function initializes the internal temp value based on only the
+ * current thermal stage and threshold. Setup threshold control and
+ * disable shutdown override.
+ */
+static int qpnp_tm_init(struct qpnp_tm_chip *chip)
+{
+	int ret;
+	u8 reg;
+
+	chip->thresh = THRESH_MIN;
+	chip->temp = DEFAULT_TEMP;
+
+	ret = qpnp_tm_read(chip, QPNP_TM_REG_STATUS, &reg);
+	if (ret < 0)
+		return ret;
+
+	chip->stage = reg & STATUS_STAGE_MASK;
+
+	if (chip->stage)
+		chip->temp = chip->thresh * TEMP_THRESH_STEP +
+			     (chip->stage - 1) * TEMP_STAGE_STEP +
+			     TEMP_THRESH_MIN;
+
+	/*
+	 * Set threshold and disable software override of stage 2 and 3
+	 * shutdowns.
+	 */
+	reg = chip->thresh & SHUTDOWN_CTRL1_THRESHOLD_MASK;
+	ret = qpnp_tm_write(chip, QPNP_TM_REG_SHUTDOWN_CTRL1, reg);
+	if (ret < 0)
+		return ret;
+
+	/* Enable the thermal alarm PMIC module in always-on mode. */
+	reg = ALARM_CTRL_FORCE_ENABLE;
+	ret = qpnp_tm_write(chip, QPNP_TM_REG_ALARM_CTRL, reg);
+
+	return ret;
+}
+
+static int qpnp_tm_probe(struct platform_device *pdev)
+{
+	struct qpnp_tm_chip *chip;
+	struct device_node *node;
+	u8 type, subtype;
+	u32 res[2];
+	int ret, irq;
+
+	node = pdev->dev.of_node;
+
+	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	dev_set_drvdata(&pdev->dev, chip);
+
+	chip->map = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!chip->map)
+		return -ENXIO;
+
+	ret = of_property_read_u32_array(node, "reg", res, 2);
+	if (ret < 0)
+		return ret;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	/* ADC based measurements are optional */
+	chip->adc = iio_channel_get(&pdev->dev, "thermal");
+	if (PTR_ERR(chip->adc) == -EPROBE_DEFER)
+		return PTR_ERR(chip->adc);
+
+	chip->base = res[0];
+
+	ret = qpnp_tm_read(chip, QPNP_TM_REG_TYPE, &type);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "could not read type\n");
+		goto fail;
+	}
+
+	ret = qpnp_tm_read(chip, QPNP_TM_REG_SUBTYPE, &subtype);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "could not read subtype\n");
+		goto fail;
+	}
+
+	if (type != QPNP_TM_TYPE || subtype != QPNP_TM_SUBTYPE) {
+		dev_err(&pdev->dev, "invalid type 0x%02x or subtype 0x%02x\n",
+			type, subtype);
+		ret = -ENODEV;
+		goto fail;
+	}
+
+	ret = qpnp_tm_init(chip);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "init failed\n");
+		goto fail;
+	}
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL, qpnp_tm_isr,
+					IRQF_ONESHOT, node->name, chip);
+	if (ret < 0)
+		goto fail;
+
+	chip->tz_dev = thermal_zone_of_sensor_register(&pdev->dev, 0, chip,
+							&qpnp_tm_sensor_ops);
+	if (IS_ERR(chip->tz_dev)) {
+		dev_err(&pdev->dev, "failed to register sensor\n");
+		ret = PTR_ERR(chip->tz_dev);
+		goto fail;
+	}
+
+	return 0;
+
+fail:
+	if (!IS_ERR(chip->adc))
+		iio_channel_release(chip->adc);
+
+	return ret;
+}
+
+static int qpnp_tm_remove(struct platform_device *pdev)
+{
+	struct qpnp_tm_chip *chip = dev_get_drvdata(&pdev->dev);
+
+	thermal_zone_of_sensor_unregister(&pdev->dev, chip->tz_dev);
+	if (!IS_ERR(chip->adc))
+		iio_channel_release(chip->adc);
+
+	return 0;
+}
+
+static const struct of_device_id qpnp_tm_match_table[] = {
+	{ .compatible = "qcom,spmi-temp-alarm" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, qpnp_tm_match_table);
+
+static struct platform_driver qpnp_tm_driver = {
+	.driver = {
+		.name = "spmi-temp-alarm",
+		.of_match_table = qpnp_tm_match_table,
+	},
+	.probe  = qpnp_tm_probe,
+	.remove = qpnp_tm_remove,
+};
+module_platform_driver(qpnp_tm_driver);
+
+MODULE_ALIAS("platform:spmi-temp-alarm");
+MODULE_DESCRIPTION("QPNP PMIC Temperature Alarm driver");
+MODULE_LICENSE("GPL v2");