iio: temperature: Add support for Azoteq IQS620AT temperature sensor

This patch adds support for the Azoteq IQS620AT temperature sensor,
capable of reporting its absolute die temperature.
Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/iio/temperature/Kconfig

@@ -4,6 +4,16 @@
 #
 menu "Temperature sensors"
 
+config IQS620AT_TEMP
+	tristate "Azoteq IQS620AT temperature sensor"
+	depends on MFD_IQS62X || COMPILE_TEST
+	help
+	  Say Y here if you want to build support for the Azoteq IQS620AT
+	  temperature sensor.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called iqs620at-temp.
+
 config LTC2983
 	tristate "Analog Devices Multi-Sensor Digital Temperature Measurement System"
 	depends on SPI

drivers/iio/temperature/Makefile

@@ -3,6 +3,7 @@
 # Makefile for industrial I/O temperature drivers
 #
 
+obj-$(CONFIG_IQS620AT_TEMP) += iqs620at-temp.o
 obj-$(CONFIG_LTC2983) += ltc2983.o
 obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
 obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o

drivers/iio/temperature/iqs620at-temp.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Azoteq IQS620AT Temperature Sensor
+ *
+ * Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
+ */
+
+#include <linux/device.h>
+#include <linux/iio/iio.h>
+#include <linux/kernel.h>
+#include <linux/mfd/iqs62x.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define IQS620_TEMP_UI_OUT			0x1A
+
+#define IQS620_TEMP_SCALE			1000
+#define IQS620_TEMP_OFFSET			(-100)
+
+static int iqs620_temp_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct iqs62x_core *iqs62x = iio_device_get_drvdata(indio_dev);
+	int ret;
+	__le16 val_buf;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = regmap_raw_read(iqs62x->regmap, IQS620_TEMP_UI_OUT,
+				      &val_buf, sizeof(val_buf));
+		if (ret)
+			return ret;
+
+		*val = le16_to_cpu(val_buf);
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = IQS620_TEMP_SCALE;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_OFFSET:
+		*val = IQS620_TEMP_OFFSET;
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info iqs620_temp_info = {
+	.read_raw = &iqs620_temp_read_raw,
+};
+
+static const struct iio_chan_spec iqs620_temp_channels[] = {
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+	},
+};
+
+static int iqs620_temp_probe(struct platform_device *pdev)
+{
+	struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
+	struct iio_dev *indio_dev;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, 0);
+	if (!indio_dev)
+		return -ENOMEM;
+
+	iio_device_set_drvdata(indio_dev, iqs62x);
+
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->channels = iqs620_temp_channels;
+	indio_dev->num_channels = ARRAY_SIZE(iqs620_temp_channels);
+	indio_dev->name = iqs62x->dev_desc->dev_name;
+	indio_dev->info = &iqs620_temp_info;
+
+	return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+static struct platform_driver iqs620_temp_platform_driver = {
+	.driver = {
+		.name = "iqs620at-temp",
+	},
+	.probe = iqs620_temp_probe,
+};
+module_platform_driver(iqs620_temp_platform_driver);
+
+MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
+MODULE_DESCRIPTION("Azoteq IQS620AT Temperature Sensor");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:iqs620at-temp");