[PATCH] iio: orientation: hid-sensor-rotation: use ext_scan_type

[David Lechner]

Make use of ext_scan_type to handle the dynamic realbits size of the
quaternion data. This lets us implement it using static data rather than
having to duplicate the channel info for each driver instance.

Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
---
This is something I noticed we could do while looking at an unrelated
bug. I'm not sure I have hardware I could test this on, so it is only
compile-tested. It would be good to get a Tested-by: from someone before
applying this. Also, I'm not sure if 8, 16 and 32-bit data are all
possible, so if someone knows, please chime in.
---
 drivers/iio/orientation/hid-sensor-rotation.c | 81 ++++++++++++++++++---------
 1 file changed, 53 insertions(+), 28 deletions(-)

diff --git a/drivers/iio/orientation/hid-sensor-rotation.c b/drivers/iio/orientation/hid-sensor-rotation.c
index e759f91a710a..2634ebf4eeb7 100644
--- a/drivers/iio/orientation/hid-sensor-rotation.c
+++ b/drivers/iio/orientation/hid-sensor-rotation.c
@@ -34,6 +34,35 @@ static const u32 rotation_sensitivity_addresses[] = {
 	HID_USAGE_SENSOR_ORIENT_QUATERNION,
 };
 
+enum {
+	DEV_ROT_SCAN_TYPE_8BIT,
+	DEV_ROT_SCAN_TYPE_16BIT,
+	DEV_ROT_SCAN_TYPE_32BIT,
+};
+
+static const struct iio_scan_type dev_rot_scan_types[] = {
+	[DEV_ROT_SCAN_TYPE_8BIT] = {
+		.sign = 's',
+		.realbits = 8,
+		/* Storage bits has to stay 32 to not break userspace. */
+		.storagebits = 32,
+		.repeat = 4,
+	},
+	[DEV_ROT_SCAN_TYPE_16BIT] = {
+		.sign = 's',
+		.realbits = 16,
+		/* Storage bits has to stay 32 to not break userspace. */
+		.storagebits = 32,
+		.repeat = 4,
+	},
+	[DEV_ROT_SCAN_TYPE_32BIT] = {
+		.sign = 's',
+		.realbits = 32,
+		.storagebits = 32,
+		.repeat = 4,
+	},
+};
+
 /* Channel definitions */
 static const struct iio_chan_spec dev_rot_channels[] = {
 	{
@@ -45,23 +74,14 @@ static const struct iio_chan_spec dev_rot_channels[] = {
 					BIT(IIO_CHAN_INFO_OFFSET) |
 					BIT(IIO_CHAN_INFO_SCALE) |
 					BIT(IIO_CHAN_INFO_HYSTERESIS),
-		.scan_index = 0
+		.scan_index = 0,
+		.has_ext_scan_type = 1,
+		.ext_scan_type = dev_rot_scan_types,
+		.num_ext_scan_type = ARRAY_SIZE(dev_rot_scan_types),
 	},
 	IIO_CHAN_SOFT_TIMESTAMP(1)
 };
 
-/* Adjust channel real bits based on report descriptor */
-static void dev_rot_adjust_channel_bit_mask(struct iio_chan_spec *chan,
-						int size)
-{
-	chan->scan_type.sign = 's';
-	/* Real storage bits will change based on the report desc. */
-	chan->scan_type.realbits = size * 8;
-	/* Maximum size of a sample to capture is u32 */
-	chan->scan_type.storagebits = sizeof(u32) * 8;
-	chan->scan_type.repeat = 4;
-}
-
 /* Channel read_raw handler */
 static int dev_rot_read_raw(struct iio_dev *indio_dev,
 				struct iio_chan_spec const *chan,
@@ -136,9 +156,27 @@ static int dev_rot_write_raw(struct iio_dev *indio_dev,
 	return ret;
 }
 
+static int dev_rot_get_current_scan_type(const struct iio_dev *indio_dev,
+					 const struct iio_chan_spec *chan)
+{
+	struct dev_rot_state *rot_state = iio_priv(indio_dev);
+
+	switch (rot_state->quaternion.size) {
+	case sizeof(s8) * 4:
+		return DEV_ROT_SCAN_TYPE_8BIT;
+	case sizeof(s16) * 4:
+		return DEV_ROT_SCAN_TYPE_16BIT;
+	case sizeof(s32) * 4:
+		return DEV_ROT_SCAN_TYPE_32BIT;
+	default:
+		return -EINVAL;
+	}
+}
+
 static const struct iio_info dev_rot_info = {
 	.read_raw_multi = &dev_rot_read_raw,
 	.write_raw = &dev_rot_write_raw,
+	.get_current_scan_type = &dev_rot_get_current_scan_type,
 };
 
 /* Callback handler to send event after all samples are received and captured */
@@ -196,7 +234,6 @@ static int dev_rot_capture_sample(struct hid_sensor_hub_device *hsdev,
 /* Parse report which is specific to an usage id*/
 static int dev_rot_parse_report(struct platform_device *pdev,
 				struct hid_sensor_hub_device *hsdev,
-				struct iio_chan_spec *channels,
 				unsigned usage_id,
 				struct dev_rot_state *st)
 {
@@ -210,9 +247,6 @@ static int dev_rot_parse_report(struct platform_device *pdev,
 	if (ret)
 		return ret;
 
-	dev_rot_adjust_channel_bit_mask(&channels[0],
-		st->quaternion.size / 4);
-
 	dev_dbg(&pdev->dev, "dev_rot %x:%x\n", st->quaternion.index,
 		st->quaternion.report_id);
 
@@ -271,22 +305,13 @@ static int hid_dev_rot_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	indio_dev->channels = devm_kmemdup(&pdev->dev, dev_rot_channels,
-					   sizeof(dev_rot_channels),
-					   GFP_KERNEL);
-	if (!indio_dev->channels) {
-		dev_err(&pdev->dev, "failed to duplicate channels\n");
-		return -ENOMEM;
-	}
-
-	ret = dev_rot_parse_report(pdev, hsdev,
-				   (struct iio_chan_spec *)indio_dev->channels,
-					hsdev->usage, rot_state);
+	ret = dev_rot_parse_report(pdev, hsdev, hsdev->usage, rot_state);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to setup attributes\n");
 		return ret;
 	}
 
+	indio_dev->channels = dev_rot_channels;
 	indio_dev->num_channels = ARRAY_SIZE(dev_rot_channels);
 	indio_dev->info = &dev_rot_info;
 	indio_dev->name = name;

---
base-commit: 0f11bb7985ceef2aeeb5c45c3c7bfff3f5a16e03
change-id: 20260214-iio-hid-sensor-rotation-cleanup-84e8410926ef

Best regards,
-- 
David Lechner <dlechner@xxxxxxxxxxxx>