iio: gyro: itg3200: add mount matrix support

This patch allows to read a mount-matrix device tree
property and report to user-space or in-kernel iio
clients.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/gyro/itg3200_core.c

@@ -242,6 +242,20 @@ static int itg3200_initial_setup(struct iio_dev *indio_dev)
 	return ret;
 }
 
+static const struct iio_mount_matrix *
+itg3200_get_mount_matrix(const struct iio_dev *indio_dev,
+			  const struct iio_chan_spec *chan)
+{
+	struct itg3200 *data = iio_priv(indio_dev);
+
+	return &data->orientation;
+}
+
+static const struct iio_chan_spec_ext_info itg3200_ext_info[] = {
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, itg3200_get_mount_matrix),
+	{ }
+};
+
 #define ITG3200_ST						\
 	{ .sign = 's', .realbits = 16, .storagebits = 16, .endianness = IIO_BE }
 
@@ -255,6 +269,7 @@ static int itg3200_initial_setup(struct iio_dev *indio_dev)
 	.address = ITG3200_REG_GYRO_ ## _mod ## OUT_H, \
 	.scan_index = ITG3200_SCAN_GYRO_ ## _mod, \
 	.scan_type = ITG3200_ST, \
+	.ext_info = itg3200_ext_info, \
 }
 
 static const struct iio_chan_spec itg3200_channels[] = {
@@ -297,6 +312,11 @@ static int itg3200_probe(struct i2c_client *client,
 
 	st = iio_priv(indio_dev);
 
+	ret = iio_read_mount_matrix(&client->dev, "mount-matrix",
+				&st->orientation);
+	if (ret)
+		return ret;
+
 	i2c_set_clientdata(client, indio_dev);
 	st->i2c = client;
 

include/linux/iio/gyro/itg3200.h

@@ -104,6 +104,7 @@
 struct itg3200 {
 	struct i2c_client	*i2c;
 	struct iio_trigger	*trig;
+	struct iio_mount_matrix orientation;
 };
 
 enum ITG3200_SCAN_INDEX {