thermal: da9062/61: Thermal junction temperature monitoring driver

Add junction temperature monitoring supervisor device driver, compatible
with the DA9062 and DA9061 PMICs. A MODULE_DEVICE_TABLE() macro is added.

If the PMIC's internal junction temperature rises above T_WARN (125 degC)
an interrupt is issued. This T_WARN level is defined as the
THERMAL_TRIP_HOT trip-wire inside the device driver.

The thermal triggering mechanism is interrupt based and happens when the
temperature rises above a given threshold level. The component cannot
return an exact temperature, it only has knowledge if the temperature is
above or below a given threshold value. A status bit must be polled to
detect when the temperature falls below that threshold level again. A
kernel work queue is configured to repeatedly poll and detect when the
temperature falls below this trip-wire, between 1 and 10 second intervals
(defaulting at 3 seconds).

This scheme is provided as an example. It would be expected that any
final implementation will also include a notify() function and any of these
settings could be altered to match the application where appropriate.

When over-temperature is reached, the interrupt from the DA9061/2 will be
repeatedly triggered. The IRQ is therefore disabled when the first
over-temperature event happens and the status bit is polled using a
work-queue until it becomes false.

This strategy is designed to allow the periodic transmission of uevents
(HOT trip point) as the first level of temperature supervision method. It
is intended for non-invasive temperature control, where the necessary
measures for cooling the system down are left to the host software. Once
the temperature falls again, the IRQ is re-enabled so a new critical
over-temperature event can be detected.

Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/Kconfig

@@ -303,6 +303,16 @@ config DB8500_CPUFREQ_COOLING
 	  bound cpufreq cooling device turns active to set CPU frequency low to
 	  cool down the CPU.
 
+config DA9062_THERMAL
+	tristate "DA9062/DA9061 Dialog Semiconductor thermal driver"
+	depends on MFD_DA9062 || COMPILE_TEST
+	depends on OF
+	help
+	  Enable this for the Dialog Semiconductor thermal sensor driver.
+	  This will report PMIC junction over-temperature for one thermal trip
+	  zone.
+	  Compatible with the DA9062 and DA9061 PMICs.
+
 config INTEL_POWERCLAMP
 	tristate "Intel PowerClamp idle injection driver"
 	depends on THERMAL

drivers/thermal/Makefile

@@ -43,6 +43,7 @@ obj-$(CONFIG_IMX_THERMAL)	+= imx_thermal.o
 obj-$(CONFIG_MAX77620_THERMAL)	+= max77620_thermal.o
 obj-$(CONFIG_QORIQ_THERMAL)	+= qoriq_thermal.o
 obj-$(CONFIG_DB8500_CPUFREQ_COOLING)	+= db8500_cpufreq_cooling.o
+obj-$(CONFIG_DA9062_THERMAL)	+= da9062-thermal.o
 obj-$(CONFIG_INTEL_POWERCLAMP)	+= intel_powerclamp.o
 obj-$(CONFIG_X86_PKG_TEMP_THERMAL)	+= x86_pkg_temp_thermal.o
 obj-$(CONFIG_INTEL_SOC_DTS_IOSF_CORE)	+= intel_soc_dts_iosf.o

drivers/thermal/da9062-thermal.c

@@ -0,0 +1,315 @@
+/*
+ * Thermal device driver for DA9062 and DA9061
+ * Copyright (C) 2017  Dialog Semiconductor
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * 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.
+ */
+
+/* When over-temperature is reached, an interrupt from the device will be
+ * triggered. Following this event the interrupt will be disabled and
+ * periodic transmission of uevents (HOT trip point) should define the
+ * first level of temperature supervision. It is expected that any final
+ * implementation of the thermal driver will include a .notify() function
+ * to implement these uevents to userspace.
+ *
+ * These uevents are intended to indicate non-invasive temperature control
+ * of the system, where the necessary measures for cooling are the
+ * responsibility of the host software. Once the temperature falls again,
+ * the IRQ is re-enabled so the start of a new over-temperature event can
+ * be detected without constant software monitoring.
+ */
+
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/thermal.h>
+#include <linux/workqueue.h>
+
+#include <linux/mfd/da9062/core.h>
+#include <linux/mfd/da9062/registers.h>
+
+/* Minimum, maximum and default polling millisecond periods are provided
+ * here as an example. It is expected that any final implementation to also
+ * include a modification of these settings to match the required
+ * application.
+ */
+#define DA9062_DEFAULT_POLLING_MS_PERIOD	3000
+#define DA9062_MAX_POLLING_MS_PERIOD		10000
+#define DA9062_MIN_POLLING_MS_PERIOD		1000
+
+#define DA9062_MILLI_CELSIUS(t)			((t) * 1000)
+
+struct da9062_thermal_config {
+	const char *name;
+};
+
+struct da9062_thermal {
+	struct da9062 *hw;
+	struct delayed_work work;
+	struct thermal_zone_device *zone;
+	enum thermal_device_mode mode;
+	struct mutex lock; /* protection for da9062_thermal temperature */
+	int temperature;
+	int irq;
+	const struct da9062_thermal_config *config;
+	struct device *dev;
+};
+
+static void da9062_thermal_poll_on(struct work_struct *work)
+{
+	struct da9062_thermal *thermal = container_of(work,
+						struct da9062_thermal,
+						work.work);
+	unsigned long delay;
+	unsigned int val;
+	int ret;
+
+	/* clear E_TEMP */
+	ret = regmap_write(thermal->hw->regmap,
+			   DA9062AA_EVENT_B,
+			   DA9062AA_E_TEMP_MASK);
+	if (ret < 0) {
+		dev_err(thermal->dev,
+			"Cannot clear the TJUNC temperature status\n");
+		goto err_enable_irq;
+	}
+
+	/* Now read E_TEMP again: it is acting like a status bit.
+	 * If over-temperature, then this status will be true.
+	 * If not over-temperature, this status will be false.
+	 */
+	ret = regmap_read(thermal->hw->regmap,
+			  DA9062AA_EVENT_B,
+			  &val);
+	if (ret < 0) {
+		dev_err(thermal->dev,
+			"Cannot check the TJUNC temperature status\n");
+		goto err_enable_irq;
+	}
+
+	if (val & DA9062AA_E_TEMP_MASK) {
+		mutex_lock(&thermal->lock);
+		thermal->temperature = DA9062_MILLI_CELSIUS(125);
+		mutex_unlock(&thermal->lock);
+		thermal_zone_device_update(thermal->zone,
+					   THERMAL_EVENT_UNSPECIFIED);
+
+		delay = msecs_to_jiffies(thermal->zone->passive_delay);
+		schedule_delayed_work(&thermal->work, delay);
+		return;
+	}
+
+	mutex_lock(&thermal->lock);
+	thermal->temperature = DA9062_MILLI_CELSIUS(0);
+	mutex_unlock(&thermal->lock);
+	thermal_zone_device_update(thermal->zone,
+				   THERMAL_EVENT_UNSPECIFIED);
+
+err_enable_irq:
+	enable_irq(thermal->irq);
+}
+
+static irqreturn_t da9062_thermal_irq_handler(int irq, void *data)
+{
+	struct da9062_thermal *thermal = data;
+
+	disable_irq_nosync(thermal->irq);
+	schedule_delayed_work(&thermal->work, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int da9062_thermal_get_mode(struct thermal_zone_device *z,
+				   enum thermal_device_mode *mode)
+{
+	struct da9062_thermal *thermal = z->devdata;
+	*mode = thermal->mode;
+	return 0;
+}
+
+static int da9062_thermal_get_trip_type(struct thermal_zone_device *z,
+					int trip,
+					enum thermal_trip_type *type)
+{
+	struct da9062_thermal *thermal = z->devdata;
+
+	switch (trip) {
+	case 0:
+		*type = THERMAL_TRIP_HOT;
+		break;
+	default:
+		dev_err(thermal->dev,
+			"Driver does not support more than 1 trip-wire\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int da9062_thermal_get_trip_temp(struct thermal_zone_device *z,
+					int trip,
+					int *temp)
+{
+	struct da9062_thermal *thermal = z->devdata;
+
+	switch (trip) {
+	case 0:
+		*temp = DA9062_MILLI_CELSIUS(125);
+		break;
+	default:
+		dev_err(thermal->dev,
+			"Driver does not support more than 1 trip-wire\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int da9062_thermal_get_temp(struct thermal_zone_device *z,
+				   int *temp)
+{
+	struct da9062_thermal *thermal = z->devdata;
+
+	mutex_lock(&thermal->lock);
+	*temp = thermal->temperature;
+	mutex_unlock(&thermal->lock);
+
+	return 0;
+}
+
+static struct thermal_zone_device_ops da9062_thermal_ops = {
+	.get_temp	= da9062_thermal_get_temp,
+	.get_mode	= da9062_thermal_get_mode,
+	.get_trip_type	= da9062_thermal_get_trip_type,
+	.get_trip_temp	= da9062_thermal_get_trip_temp,
+};
+
+static const struct da9062_thermal_config da9062_config = {
+	.name = "da9062-thermal",
+};
+
+static const struct of_device_id da9062_compatible_reg_id_table[] = {
+	{ .compatible = "dlg,da9062-thermal", .data = &da9062_config },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, da9062_compatible_reg_id_table);
+
+static int da9062_thermal_probe(struct platform_device *pdev)
+{
+	struct da9062 *chip = dev_get_drvdata(pdev->dev.parent);
+	struct da9062_thermal *thermal;
+	unsigned int pp_tmp = DA9062_DEFAULT_POLLING_MS_PERIOD;
+	const struct of_device_id *match;
+	int ret = 0;
+
+	match = of_match_node(da9062_compatible_reg_id_table,
+			      pdev->dev.of_node);
+	if (!match)
+		return -ENXIO;
+
+	if (pdev->dev.of_node) {
+		if (!of_property_read_u32(pdev->dev.of_node,
+					  "polling-delay-passive",
+					  &pp_tmp)) {
+			if (pp_tmp < DA9062_MIN_POLLING_MS_PERIOD ||
+			    pp_tmp > DA9062_MAX_POLLING_MS_PERIOD) {
+				dev_warn(&pdev->dev,
+					 "Out-of-range polling period %d ms\n",
+					 pp_tmp);
+				pp_tmp = DA9062_DEFAULT_POLLING_MS_PERIOD;
+			}
+		}
+	}
+
+	thermal = devm_kzalloc(&pdev->dev, sizeof(struct da9062_thermal),
+			       GFP_KERNEL);
+	if (!thermal) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	thermal->config = match->data;
+	thermal->hw = chip;
+	thermal->mode = THERMAL_DEVICE_ENABLED;
+	thermal->dev = &pdev->dev;
+
+	INIT_DELAYED_WORK(&thermal->work, da9062_thermal_poll_on);
+	mutex_init(&thermal->lock);
+
+	thermal->zone = thermal_zone_device_register(thermal->config->name,
+					1, 0, thermal,
+					&da9062_thermal_ops, NULL, pp_tmp,
+					0);
+	if (IS_ERR(thermal->zone)) {
+		dev_err(&pdev->dev, "Cannot register thermal zone device\n");
+		ret = PTR_ERR(thermal->zone);
+		goto err;
+	}
+
+	dev_dbg(&pdev->dev,
+		"TJUNC temperature polling period set at %d ms\n",
+		thermal->zone->passive_delay);
+
+	ret = platform_get_irq_byname(pdev, "THERMAL");
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to get platform IRQ.\n");
+		goto err_zone;
+	}
+	thermal->irq = ret;
+
+	ret = request_threaded_irq(thermal->irq, NULL,
+				   da9062_thermal_irq_handler,
+				   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+				   "THERMAL", thermal);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"Failed to request thermal device IRQ.\n");
+		goto err_zone;
+	}
+
+	platform_set_drvdata(pdev, thermal);
+	return 0;
+
+err_zone:
+	thermal_zone_device_unregister(thermal->zone);
+err:
+	return ret;
+}
+
+static int da9062_thermal_remove(struct platform_device *pdev)
+{
+	struct	da9062_thermal *thermal = platform_get_drvdata(pdev);
+
+	free_irq(thermal->irq, thermal);
+	cancel_delayed_work_sync(&thermal->work);
+	thermal_zone_device_unregister(thermal->zone);
+	return 0;
+}
+
+static struct platform_driver da9062_thermal_driver = {
+	.probe	= da9062_thermal_probe,
+	.remove	= da9062_thermal_remove,
+	.driver	= {
+		.name	= "da9062-thermal",
+		.of_match_table = da9062_compatible_reg_id_table,
+	},
+};
+
+module_platform_driver(da9062_thermal_driver);
+
+MODULE_AUTHOR("Steve Twiss");
+MODULE_DESCRIPTION("Thermal TJUNC device driver for Dialog DA9062 and DA9061");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:da9062-thermal");