rM2: thermal: Copy the rM2 sy7636a_thermal driver

Copy the rM2 zero-sugar branch
(https://github.com/reMarkable/linux/tree/zero-sugar) to the new kernel.

Signed-off-by: Alistair Francis <alistair@alistair23.me>

drivers/thermal/Kconfig

@@ -403,6 +403,13 @@ 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.
+
 config TANGO_THERMAL
 	tristate "Tango thermal management"
 	depends on ARCH_TANGO || COMPILE_TEST

drivers/thermal/Makefile

@@ -50,6 +50,7 @@ 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

drivers/thermal/sy7636a_thermal.c

@@ -0,0 +1,120 @@
+/*
+ * Functions to access SY3686A power management chip temperature
+ *
+ * Copyright (C) 2019 reMarkable AS - http://www.remarkable.com/
+ *
+ * Author: Lars Ivar Miljeteig <lars.ivar.miljeteig@remarkable.com>
+ *
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#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;
+
+	mutex_lock(&data->sy7636a->reglock);
+
+	ret = regmap_read(data->sy7636a->regmap,
+			SY7636A_REG_OPERATION_MODE_CRL, &mode_ctr);
+	if (ret)
+		goto done;
+
+	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)
+			goto done;
+		usleep_range(1000, 1500);
+	}
+
+	ret = regmap_read(data->sy7636a->regmap,
+			SY7636A_REG_TERMISTOR_READOUT, &reg_val);
+	if (ret)
+		goto done;
+
+	if (!isVoltageActive) {
+		ret = regmap_write(data->sy7636a->regmap,
+				SY7636A_REG_OPERATION_MODE_CRL,
+				mode_ctr);
+		if (ret)
+			goto done;
+	}
+
+	*res = *((signed char*)&reg_val);
+	*res *= 1000;
+
+	done:
+	mutex_unlock(&data->sy7636a->reglock);
+
+	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");