[PATCH v13 5/9] thermal: sy7636a: Add thermal driver for sy7636a

[Alistair Francis]

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

Signed-off-by: Alistair Francis <alistair at alistair23.me>
---
 drivers/thermal/Kconfig           |  6 ++
 drivers/thermal/Makefile          |  1 +
 drivers/thermal/sy7636a_thermal.c | 94 +++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+)
 create mode 100644 drivers/thermal/sy7636a_thermal.c

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index d7f44deab5b1..6ee0e7de1b37 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -450,6 +450,12 @@ depends on (ARCH_STI || ARCH_STM32) && OF
 source "drivers/thermal/st/Kconfig"
 endmenu
 
+config SY7636A_THERMAL
+	tristate "SY7636A thermal management"
+	help
+	  Enable the sy7636a thermal driver, which supports the
+	  temperature sensor embedded in Silabs SY7636A IC.
+
 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..9e58305ca3ce
--- /dev/null
+++ b/drivers/thermal/sy7636a_thermal.c
@@ -0,0 +1,94 @@
+// 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 at remarkable.com>
+ *          Alistair Francis <alistair at alistair23.me>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/thermal.h>
+
+#include <linux/mfd/sy7636a.h>
+
+static int sy7636a_get_temp(void *arg, int *res)
+{
+	unsigned int mode_ctr;
+	int ret, reg_val;
+	struct regmap *regmap = arg;
+	bool isVoltageActive;
+
+	ret = regmap_read(regmap,
+			SY7636A_REG_OPERATION_MODE_CRL, &mode_ctr);
+	if (ret)
+		return ret;
+
+	isVoltageActive = mode_ctr & SY7636A_OPERATION_MODE_CRL_ONOFF;
+
+	/* If operation mode isn't set to control, then let's set it. */
+	if (!isVoltageActive) {
+		ret = regmap_write(regmap,
+				SY7636A_REG_OPERATION_MODE_CRL,
+				mode_ctr | SY7636A_OPERATION_MODE_CRL_ONOFF);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_read(regmap,
+			SY7636A_REG_TERMISTOR_READOUT, &reg_val);
+	if (ret)
+		return ret;
+
+	/* Restore the operation mode if it wasn't set */
+	if (!isVoltageActive) {
+		ret = regmap_write(regmap,
+				SY7636A_REG_OPERATION_MODE_CRL,
+				mode_ctr);
+		if (ret)
+			return ret;
+	}
+
+	*res = reg_val * 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 regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	struct thermal_zone_device *thermal_zone_dev;
+
+	thermal_zone_dev = devm_thermal_zone_of_sensor_register(
+			pdev->dev.parent,
+			0,
+			regmap,
+			&ops);
+
+	return PTR_ERR_OR_ZERO(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 at remarkable.com>");
+MODULE_DESCRIPTION("SY7636A thermal driver");
+MODULE_LICENSE("GPL v2");
-- 
2.31.1