[PATCH v4 4/4] iio: imu: fxos8700: fix MAGN sensor scale and unit

[carlos.song@nxp.com]

From: Carlos Song <carlos.song@nxp.com>

+/-1200uT is a MAGN sensor full measurement range. Magnetometer scale
is the magnetic sensitivity parameter. It is referenced as 0.1uT
according to datasheet and magnetometer channel unit is Gauss in
sysfs-bus-iio documentation. Gauss and uTesla unit conversion
relationship as follows: 0.1uT = 0.001Gs.

Set magnetometer scale and available magnetometer scale as fixed 0.001Gs.

Fixes: 84e5ddd5c46e ("iio: imu: Add support for the FXOS8700 IMU")
Signed-off-by: Carlos Song <carlos.song@nxp.com>
---
Changes for V4:
- None
Changes for V3:
- Modify the magnetometer sensitivity unit "g" to standard unit "Gs"
- Check and confirm uscale value is correct. The readback of
  MAGN scale is 0.001 Gs
- Rework commit log
Changes for V2:
- Modify the magnetometer sensitivity unit to be consistent with the
  documentation as 0.001g
- Rework commit log
---
 drivers/iio/imu/fxos8700_core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/imu/fxos8700_core.c b/drivers/iio/imu/fxos8700_core.c
index 7b370bd643a1..8320a3b6f942 100644
--- a/drivers/iio/imu/fxos8700_core.c
+++ b/drivers/iio/imu/fxos8700_core.c
@@ -351,7 +351,7 @@ static int fxos8700_set_scale(struct fxos8700_data *data,
 	struct device *dev = regmap_get_device(data->regmap);
 
 	if (t == FXOS8700_MAGN) {
-		dev_err(dev, "Magnetometer scale is locked at 1200uT\n");
+		dev_err(dev, "Magnetometer scale is locked at 0.001Gs\n");
 		return -EINVAL;
 	}
 
@@ -396,7 +396,7 @@ static int fxos8700_get_scale(struct fxos8700_data *data,
 	static const int scale_num = ARRAY_SIZE(fxos8700_accel_scale);
 
 	if (t == FXOS8700_MAGN) {
-		*uscale = 1200; /* Magnetometer is locked at 1200uT */
+		*uscale = 1000; /* Magnetometer is locked at 0.001Gs */
 		return 0;
 	}
 
@@ -587,7 +587,7 @@ static IIO_CONST_ATTR(in_accel_sampling_frequency_available,
 static IIO_CONST_ATTR(in_magn_sampling_frequency_available,
 		      "1.5625 6.25 12.5 50 100 200 400 800");
 static IIO_CONST_ATTR(in_accel_scale_available, "0.000244 0.000488 0.000976");
-static IIO_CONST_ATTR(in_magn_scale_available, "0.000001200");
+static IIO_CONST_ATTR(in_magn_scale_available, "0.001000");
 
 static struct attribute *fxos8700_attrs[] = {
 	&iio_const_attr_in_accel_sampling_frequency_available.dev_attr.attr,
-- 
2.34.1