[PATCH v2 1/3] iio: hid-sensor-als: Allocate channels dynamically

[Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>]

Instead of assuming that every channel defined statically by
als_channels[] is present, allocate dynamically based on presence of the
respective usage id in the descriptor. This will allow to register ALS
with limited channel support. Append the timestamp as the last channel.

There is no intentional function changes done.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
---
v2:
New change

 drivers/iio/light/hid-sensor-als.c | 57 ++++++++++++++++++------------
 1 file changed, 35 insertions(+), 22 deletions(-)

diff --git a/drivers/iio/light/hid-sensor-als.c b/drivers/iio/light/hid-sensor-als.c
index 5cd27f04b45e..e57ad1946b56 100644
--- a/drivers/iio/light/hid-sensor-als.c
+++ b/drivers/iio/light/hid-sensor-als.c
@@ -236,14 +236,21 @@ static int als_capture_sample(struct hid_sensor_hub_device *hsdev,
 
 /* Parse report which is specific to an usage id*/
 static int als_parse_report(struct platform_device *pdev,
-				struct hid_sensor_hub_device *hsdev,
-				struct iio_chan_spec *channels,
-				unsigned usage_id,
-				struct als_state *st)
+			    struct hid_sensor_hub_device *hsdev,
+			    struct iio_chan_spec **channels_out,
+			    int *size_channels_out,
+			    unsigned int usage_id,
+			    struct als_state *st)
 {
-	int ret;
+	struct iio_chan_spec *channels;
+	int ret, index = 0;
 	int i;
 
+	channels = devm_kcalloc(&pdev->dev, ARRAY_SIZE(als_channels),
+				sizeof(als_channels), GFP_KERNEL);
+	if (!channels)
+		return -ENOMEM;
+
 	for (i = 0; i <= CHANNEL_SCAN_INDEX_ILLUM; ++i) {
 		ret = sensor_hub_input_get_attribute_info(hsdev,
 						HID_INPUT_REPORT,
@@ -251,9 +258,11 @@ static int als_parse_report(struct platform_device *pdev,
 						HID_USAGE_SENSOR_LIGHT_ILLUM,
 						&st->als[i]);
 		if (ret < 0)
-			return ret;
-		als_adjust_channel_bit_mask(channels, i, st->als[i].size);
+			break;
 
+		channels[i] = als_channels[i];
+		als_adjust_channel_bit_mask(channels, i, st->als[i].size);
+		++index;
 		dev_dbg(&pdev->dev, "als %x:%x\n", st->als[i].index,
 			st->als[i].report_id);
 	}
@@ -262,17 +271,24 @@ static int als_parse_report(struct platform_device *pdev,
 				&st->als[CHANNEL_SCAN_INDEX_INTENSITY],
 				&st->scale_pre_decml, &st->scale_post_decml);
 
-	return ret;
+	*channels_out = channels;
+	*size_channels_out = index;
+
+	if (!index)
+		ret = -ENODEV;
+
+	return 0;
 }
 
 /* Function to initialize the processing for usage id */
 static int hid_als_probe(struct platform_device *pdev)
 {
-	int ret = 0;
+	int ret = 0, max_channel_index;
 	static const char *name = "als";
 	struct iio_dev *indio_dev;
 	struct als_state *als_state;
 	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
+	struct iio_chan_spec *channels;
 
 	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(struct als_state));
 	if (!indio_dev)
@@ -293,24 +309,21 @@ static int hid_als_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	indio_dev->channels = devm_kmemdup(&pdev->dev, als_channels,
-					   sizeof(als_channels), GFP_KERNEL);
-	if (!indio_dev->channels) {
-		dev_err(&pdev->dev, "failed to duplicate channels\n");
-		return -ENOMEM;
-	}
-
-	ret = als_parse_report(pdev, hsdev,
-			       (struct iio_chan_spec *)indio_dev->channels,
-			       hsdev->usage,
-			       als_state);
+	ret = als_parse_report(pdev, hsdev, &channels, &max_channel_index,
+			       hsdev->usage, als_state);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to setup attributes\n");
 		return ret;
 	}
 
-	indio_dev->num_channels =
-				ARRAY_SIZE(als_channels);
+	/* Add timestamp channel */
+	channels[max_channel_index] = als_channels[CHANNEL_SCAN_INDEX_TIMESTAMP];
+	channels[max_channel_index].scan_index = max_channel_index;
+
+	/* +1 for adding timestamp channel */
+	indio_dev->num_channels = max_channel_index + 1;
+
+	indio_dev->channels = channels;
 	indio_dev->info = &als_info;
 	indio_dev->name = name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
-- 
2.43.0