[PATCH v7 2/6] thermal: sy7636a: Add thermal driver for sy7636a

[Alistair Francis <alistair@alistair23.me>]

From: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.no>

Add thermal driver to enable kernel based polling
and shutdown of device for temperatures out of spec

Signed-off-by: Alistair Francis <alistair@alistair23.me>
---
 drivers/thermal/Kconfig           |   7 ++
 drivers/thermal/Makefile          |   1 +
 drivers/thermal/sy7636a_thermal.c | 107 ++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+)
 create mode 100644 drivers/thermal/sy7636a_thermal.c

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index d7f44deab5b1..7112c63d9021 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -450,6 +450,13 @@ depends on (ARCH_STI || ARCH_STM32) && OF
 source "drivers/thermal/st/Kconfig"
 endmenu
 
+config SY7636A_THERMAL
+	tristate "SY7636A thermal management"
+	depends on MFD_SY7636A
+	help
+	  Enable the sy7636a thermal driver, which supports the
+	  temperature sensor embedded in Silabs SY7636A chip.
+
 source "drivers/thermal/tegra/Kconfig"
 
 config GENERIC_ADC_THERMAL
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 82fc3e616e54..2e1aca8a0a09 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_DA9062_THERMAL)	+= da9062-thermal.o
 obj-y				+= intel/
 obj-$(CONFIG_TI_SOC_THERMAL)	+= ti-soc-thermal/
 obj-y				+= st/
+obj-$(CONFIG_SY7636A_THERMAL)	+= sy7636a_thermal.o
 obj-$(CONFIG_QCOM_TSENS)	+= qcom/
 obj-y				+= tegra/
 obj-$(CONFIG_HISI_THERMAL)     += hisi_thermal.o
diff --git a/drivers/thermal/sy7636a_thermal.c b/drivers/thermal/sy7636a_thermal.c
new file mode 100644
index 000000000000..705a16fb1045
--- /dev/null
+++ b/drivers/thermal/sy7636a_thermal.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Functions to access SY3686A power management chip temperature
+//
+// Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
+//
+// Authors: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>
+//          Alistair Francis <alistair@alistair23.me>
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#include <linux/mfd/sy7636a.h>
+
+struct sy7636a_data {
+	struct sy7636a *sy7636a;
+	struct thermal_zone_device *thermal_zone_dev;
+};
+
+static int sy7636a_get_temp(void *arg, int *res)
+{
+	unsigned int reg_val, mode_ctr;
+	int ret;
+	struct sy7636a_data *data = arg;
+	bool isVoltageActive;
+
+	ret = regmap_read(data->sy7636a->regmap,
+			SY7636A_REG_OPERATION_MODE_CRL, &mode_ctr);
+	if (ret)
+		return ret;
+
+	isVoltageActive = mode_ctr & SY7636A_OPERATION_MODE_CRL_ONOFF;
+
+	if (!isVoltageActive) {
+		ret = regmap_write(data->sy7636a->regmap,
+				SY7636A_REG_OPERATION_MODE_CRL,
+				mode_ctr | SY7636A_OPERATION_MODE_CRL_ONOFF);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_read(data->sy7636a->regmap,
+			SY7636A_REG_TERMISTOR_READOUT, &reg_val);
+	if (ret)
+		return ret;
+
+	if (!isVoltageActive) {
+		ret = regmap_write(data->sy7636a->regmap,
+				SY7636A_REG_OPERATION_MODE_CRL,
+				mode_ctr);
+		if (ret)
+			return ret;
+	}
+
+	*res = *((signed char*)&reg_val);
+	*res *= 1000;
+
+	return ret;
+}
+
+static const struct thermal_zone_of_device_ops ops = {
+	.get_temp	= sy7636a_get_temp,
+};
+
+static int sy7636a_thermal_probe(struct platform_device *pdev)
+{
+	struct sy7636a *sy7636a = dev_get_drvdata(pdev->dev.parent);
+	struct sy7636a_data *data;
+
+	if (!sy7636a)
+		return -EPROBE_DEFER;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(struct sy7636a_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, data);
+
+	data->sy7636a = sy7636a;
+	data->thermal_zone_dev = devm_thermal_zone_of_sensor_register(
+			pdev->dev.parent,
+			0,
+			data,
+			&ops);
+
+	return PTR_ERR_OR_ZERO(data->thermal_zone_dev);
+}
+
+static const struct platform_device_id sy7636a_thermal_id_table[] = {
+	{ "sy7636a-thermal", },
+	{ }
+};
+MODULE_DEVICE_TABLE(platform, sy7636a_thermal_id_table);
+
+static struct platform_driver sy7636a_thermal_driver = {
+	.driver = {
+		.name = "sy7636a-thermal",
+	},
+	.probe = sy7636a_thermal_probe,
+	.id_table = sy7636a_thermal_id_table,
+};
+module_platform_driver(sy7636a_thermal_driver);
+
+MODULE_AUTHOR("Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>");
+MODULE_DESCRIPTION("SY7636A thermal driver");
+MODULE_LICENSE("GPL v2");
-- 
2.31.1