From: Carlos Song <carlos.song@xxxxxxx>
ACCEL output data registers contain the X-axis, Y-axis, and Z-axis
14-bit left-justified sample data and MAGN output data registers
contain the X-axis, Y-axis, and Z-axis 16-bit sample data. The ACCEL
raw register output data should be divided by 4 before sent to
userspace.
Apply a 2 bits signed right shift to the raw data from ACCEL output
data register but keep that from MAGN sensor as the origin.
Fixes: 84e5ddd5c46e ("iio: imu: Add support for the FXOS8700 IMU")
Signed-off-by: Carlos Song <carlos.song@xxxxxxx>
---
Changes for V2:
- Store the shift in the switch and apply a shift by 2 for ACCEL
and shift by 0 for MAGN
- Confirm the scaling is still correct for the acceleration channels
given we are effectively dividing by 4 compared to the previous code
- Rework the comment
diff --git a/drivers/iio/imu/fxos8700_core.c b/drivers/iio/imu/fxos8700_core.c
index b62bc92bbacc..d2e784628820 100644
--- a/drivers/iio/imu/fxos8700_core.c
+++ b/drivers/iio/imu/fxos8700_core.c
@@ -394,6 +394,7 @@ static int fxos8700_get_data(struct fxos8700_data *data, int chan_type,
int axis, int *val)
{
u8 base, reg;
+ s16 tmp;
int ret;
/*
@@ -421,8 +422,33 @@ static int fxos8700_get_data(struct fxos8700_data *data, int chan_type,
/* Convert axis to buffer index */
reg = axis - IIO_MOD_X;
+ /*
+ * Convert to native endianness. The accel data and magn data
+ * are signed, so a forced type conversion is needed.
+ */
+ tmp = be16_to_cpu(data->buf[reg]);
+
+ /*
+ * ACCEL output data registers contain the X-axis, Y-axis, and Z-axis
+ * 14-bit left-justified sample data and MAGN output data registers
+ * contain the X-axis, Y-axis, and Z-axis 16-bit sample data. Apply
+ * a signed 2 bits right shift to the readback raw data from ACCEL
+ * output data register and keep that from MAGN sensor as the origin.
+ * Value should be extended to 32 bit.
+ */
+ switch (chan_type) {
+ case IIO_ACCEL:
+ tmp = tmp >> 2;
+ break;
+ case IIO_MAGN:
+ tmp = tmp >> 0;
+ break;
+ default:
+ return -EINVAL;
+ }
+
/* Convert to native endianness */
- *val = sign_extend32(be16_to_cpu(data->buf[reg]), 15);
+ *val = sign_extend32(tmp, 15);
return 0;
}
--
2.34.1
