iio: magnetometer: hmc5843: 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/magnetometer/hmc5843.h

@@ -43,6 +43,7 @@ struct hmc5843_data {
 	struct mutex lock;
 	struct regmap *regmap;
 	const struct hmc5843_chip_info *variant;
+	struct iio_mount_matrix orientation;
 	__be16 buffer[8];
 };
 

drivers/iio/magnetometer/hmc5843_core.c

@@ -237,6 +237,15 @@ int hmc5843_set_measurement_configuration(struct iio_dev *indio_dev,
 	return hmc5843_set_meas_conf(data, meas_conf);
 }
 
+static const struct iio_mount_matrix *
+hmc5843_get_mount_matrix(const struct iio_dev *indio_dev,
+			  const struct iio_chan_spec *chan)
+{
+	struct hmc5843_data *data = iio_priv(indio_dev);
+
+	return &data->orientation;
+}
+
 static const struct iio_enum hmc5843_meas_conf_enum = {
 	.items = hmc5843_meas_conf_modes,
 	.num_items = ARRAY_SIZE(hmc5843_meas_conf_modes),
@@ -247,7 +256,8 @@ static const struct iio_enum hmc5843_meas_conf_enum = {
 static const struct iio_chan_spec_ext_info hmc5843_ext_info[] = {
 	IIO_ENUM("meas_conf", true, &hmc5843_meas_conf_enum),
 	IIO_ENUM_AVAILABLE("meas_conf", &hmc5843_meas_conf_enum),
-	{ },
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, hmc5843_get_mount_matrix),
+	{ }
 };
 
 static const struct iio_enum hmc5983_meas_conf_enum = {
@@ -260,7 +270,8 @@ static const struct iio_enum hmc5983_meas_conf_enum = {
 static const struct iio_chan_spec_ext_info hmc5983_ext_info[] = {
 	IIO_ENUM("meas_conf", true, &hmc5983_meas_conf_enum),
 	IIO_ENUM_AVAILABLE("meas_conf", &hmc5983_meas_conf_enum),
-	{ },
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, hmc5843_get_mount_matrix),
+	{ }
 };
 
 static
@@ -635,6 +646,11 @@ int hmc5843_common_probe(struct device *dev, struct regmap *regmap,
 	data->variant = &hmc5843_chip_info_tbl[id];
 	mutex_init(&data->lock);
 
+	ret = iio_read_mount_matrix(dev, "mount-matrix",
+				&data->orientation);
+	if (ret)
+		return ret;
+
 	indio_dev->dev.parent = dev;
 	indio_dev->name = name;
 	indio_dev->info = &hmc5843_info;