iio: imu: inv_icm42600: add temperature sensor support

Add temperature channel in gyroscope and accelerometer devices.

Temperature is available in full 16 bits resolution when reading
register and in low 8 bits resolution in the FIFO. Return full
precision raw temperature with corresponding scale and offset.

Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c

@@ -13,6 +13,7 @@
 #include <linux/iio/iio.h>
 
 #include "inv_icm42600.h"
+#include "inv_icm42600_temp.h"
 
 #define INV_ICM42600_ACCEL_CHAN(_modifier, _index, _ext_info)		\
 	{								\
@@ -45,6 +46,7 @@ enum inv_icm42600_accel_scan {
 	INV_ICM42600_ACCEL_SCAN_X,
 	INV_ICM42600_ACCEL_SCAN_Y,
 	INV_ICM42600_ACCEL_SCAN_Z,
+	INV_ICM42600_ACCEL_SCAN_TEMP,
 };
 
 static const struct iio_chan_spec_ext_info inv_icm42600_accel_ext_infos[] = {
@@ -59,6 +61,7 @@ static const struct iio_chan_spec inv_icm42600_accel_channels[] = {
 				inv_icm42600_accel_ext_infos),
 	INV_ICM42600_ACCEL_CHAN(IIO_MOD_Z, INV_ICM42600_ACCEL_SCAN_Z,
 				inv_icm42600_accel_ext_infos),
+	INV_ICM42600_TEMP_CHAN(INV_ICM42600_ACCEL_SCAN_TEMP),
 };
 
 static int inv_icm42600_accel_read_sensor(struct inv_icm42600_state *st,
@@ -450,8 +453,14 @@ static int inv_icm42600_accel_read_raw(struct iio_dev *indio_dev,
 	int16_t data;
 	int ret;
 
-	if (chan->type != IIO_ACCEL)
+	switch (chan->type) {
+	case IIO_ACCEL:
+		break;
+	case IIO_TEMP:
+		return inv_icm42600_temp_read_raw(indio_dev, chan, val, val2, mask);
+	default:
 		return -EINVAL;
+	}
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:

drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c

@@ -13,6 +13,7 @@
 #include <linux/iio/iio.h>
 
 #include "inv_icm42600.h"
+#include "inv_icm42600_temp.h"
 
 #define INV_ICM42600_GYRO_CHAN(_modifier, _index, _ext_info)		\
 	{								\
@@ -45,6 +46,7 @@ enum inv_icm42600_gyro_scan {
 	INV_ICM42600_GYRO_SCAN_X,
 	INV_ICM42600_GYRO_SCAN_Y,
 	INV_ICM42600_GYRO_SCAN_Z,
+	INV_ICM42600_GYRO_SCAN_TEMP,
 };
 
 static const struct iio_chan_spec_ext_info inv_icm42600_gyro_ext_infos[] = {
@@ -59,6 +61,7 @@ static const struct iio_chan_spec inv_icm42600_gyro_channels[] = {
 			       inv_icm42600_gyro_ext_infos),
 	INV_ICM42600_GYRO_CHAN(IIO_MOD_Z, INV_ICM42600_GYRO_SCAN_Z,
 			       inv_icm42600_gyro_ext_infos),
+	INV_ICM42600_TEMP_CHAN(INV_ICM42600_GYRO_SCAN_TEMP),
 };
 
 static int inv_icm42600_gyro_read_sensor(struct inv_icm42600_state *st,
@@ -461,8 +464,14 @@ static int inv_icm42600_gyro_read_raw(struct iio_dev *indio_dev,
 	int16_t data;
 	int ret;
 
-	if (chan->type != IIO_ANGL_VEL)
+	switch (chan->type) {
+	case IIO_ANGL_VEL:
+		break;
+	case IIO_TEMP:
+		return inv_icm42600_temp_read_raw(indio_dev, chan, val, val2, mask);
+	default:
 		return -EINVAL;
+	}
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:

drivers/iio/imu/inv_icm42600/inv_icm42600_temp.c

@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020 Invensense, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+
+#include "inv_icm42600.h"
+#include "inv_icm42600_temp.h"
+
+static int inv_icm42600_temp_read(struct inv_icm42600_state *st, int16_t *temp)
+{
+	struct device *dev = regmap_get_device(st->map);
+	__be16 *raw;
+	int ret;
+
+	pm_runtime_get_sync(dev);
+	mutex_lock(&st->lock);
+
+	ret = inv_icm42600_set_temp_conf(st, true, NULL);
+	if (ret)
+		goto exit;
+
+	raw = (__be16 *)&st->buffer[0];
+	ret = regmap_bulk_read(st->map, INV_ICM42600_REG_TEMP_DATA, raw, sizeof(*raw));
+	if (ret)
+		goto exit;
+
+	*temp = (int16_t)be16_to_cpup(raw);
+	if (*temp == INV_ICM42600_DATA_INVALID)
+		ret = -EINVAL;
+
+exit:
+	mutex_unlock(&st->lock);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	return ret;
+}
+
+int inv_icm42600_temp_read_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int *val, int *val2, long mask)
+{
+	struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
+	int16_t temp;
+	int ret;
+
+	if (chan->type != IIO_TEMP)
+		return -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		ret = inv_icm42600_temp_read(st, &temp);
+		iio_device_release_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		*val = temp;
+		return IIO_VAL_INT;
+	/*
+	 * T°C = (temp / 132.48) + 25
+	 * Tm°C = 1000 * ((temp * 100 / 13248) + 25)
+	 * scale: 100000 / 13248 ~= 7.548309
+	 * offset: 25000
+	 */
+	case IIO_CHAN_INFO_SCALE:
+		*val = 7;
+		*val2 = 548309;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = 25000;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}

drivers/iio/imu/inv_icm42600/inv_icm42600_temp.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2020 Invensense, Inc.
+ */
+
+#ifndef INV_ICM42600_TEMP_H_
+#define INV_ICM42600_TEMP_H_
+
+#include <linux/iio/iio.h>
+
+#define INV_ICM42600_TEMP_CHAN(_index)					\
+	{								\
+		.type = IIO_TEMP,					\
+		.info_mask_separate =					\
+			BIT(IIO_CHAN_INFO_RAW) |			\
+			BIT(IIO_CHAN_INFO_OFFSET) |			\
+			BIT(IIO_CHAN_INFO_SCALE),			\
+		.scan_index = _index,					\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 16,					\
+			.storagebits = 16,				\
+		},							\
+	}
+
+int inv_icm42600_temp_read_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int *val, int *val2, long mask);
+
+#endif