iio: accel: bma180: 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: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/bma180.c

@@ -116,6 +116,7 @@ struct bma180_data {
 	struct i2c_client *client;
 	struct iio_trigger *trig;
 	const struct bma180_part_info *part_info;
+	struct iio_mount_matrix orientation;
 	struct mutex mutex;
 	bool sleep_state;
 	int scale;
@@ -561,6 +562,15 @@ static int bma180_set_power_mode(struct iio_dev *indio_dev,
 	return ret;
 }
 
+static const struct iio_mount_matrix *
+bma180_accel_get_mount_matrix(const struct iio_dev *indio_dev,
+				const struct iio_chan_spec *chan)
+{
+	struct bma180_data *data = iio_priv(indio_dev);
+
+	return &data->orientation;
+}
+
 static const struct iio_enum bma180_power_mode_enum = {
 	.items = bma180_power_modes,
 	.num_items = ARRAY_SIZE(bma180_power_modes),
@@ -571,7 +581,8 @@ static const struct iio_enum bma180_power_mode_enum = {
 static const struct iio_chan_spec_ext_info bma180_ext_info[] = {
 	IIO_ENUM("power_mode", true, &bma180_power_mode_enum),
 	IIO_ENUM_AVAILABLE("power_mode", &bma180_power_mode_enum),
-	{ },
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, bma180_accel_get_mount_matrix),
+	{ }
 };
 
 #define BMA180_ACC_CHANNEL(_axis, _bits) {				\
@@ -722,6 +733,11 @@ static int bma180_probe(struct i2c_client *client,
 		chip = id->driver_data;
 	data->part_info = &bma180_part_info[chip];
 
+	ret = iio_read_mount_matrix(&client->dev, "mount-matrix",
+				&data->orientation);
+	if (ret)
+		return ret;
+
 	ret = data->part_info->chip_config(data);
 	if (ret < 0)
 		goto err_chip_disable;