patch "iio: imu: fxos8700: fix IMU data bits returned to user space" added to char-misc-linus

This is a note to let you know that I've just added the patch titled

iio: imu: fxos8700: fix IMU data bits returned to user space

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From a53f945879c0cb9de3a4c05a665f5157884b5208 Mon Sep 17 00:00:00 2001
From: Carlos Song <[email protected]>
Date: Thu, 8 Dec 2022 15:19:08 +0800
Subject: iio: imu: fxos8700: fix IMU data bits returned to user space

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.

---
 drivers/iio/imu/fxos8700_core.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

index b62bc92bbacc..06948a8cc315 100644
@@ -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:
+		/* Nothing to do */
+		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;
 }

2.39.1