iio: hid-sensor-prox: support multi-channel SCALE calculation

With the introduction of multi-channel support in commit 596ef5c
("iio: hid-sensor-prox: Add support for more channels"), each channel
requires an independent SCALE calculation, but the existing code only
calculates SCALE for a single channel.

Addresses the problem by modifying the driver to perform independent
SCALE calculations for each channel.

Cc: stable@vger.kernel.org
Fixes: 596ef5c ("iio: hid-sensor-prox: Add support for more channels")
Signed-off-by: Zhang Lixu <lixu.zhang@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20250331055022.1149736-3-lixu.zhang@intel.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: lixuzha

drivers/iio/common/hid-sensors/hid-sensor-attributes.c

@@ -66,6 +66,10 @@ static struct {
 	{HID_USAGE_SENSOR_HUMIDITY, 0, 1000, 0},
 	{HID_USAGE_SENSOR_HINGE, 0, 0, 17453293},
 	{HID_USAGE_SENSOR_HINGE, HID_USAGE_SENSOR_UNITS_DEGREES, 0, 17453293},
+
+	{HID_USAGE_SENSOR_HUMAN_PRESENCE, 0, 1, 0},
+	{HID_USAGE_SENSOR_HUMAN_PROXIMITY, 0, 1, 0},
+	{HID_USAGE_SENSOR_HUMAN_ATTENTION, 0, 1, 0},
 };
 
 static void simple_div(int dividend, int divisor, int *whole,

drivers/iio/light/hid-sensor-prox.c

@@ -34,9 +34,9 @@ struct prox_state {
 	struct iio_chan_spec channels[MAX_CHANNELS];
 	u32 channel2usage[MAX_CHANNELS];
 	u32 human_presence[MAX_CHANNELS];
-	int scale_pre_decml;
-	int scale_post_decml;
-	int scale_precision;
+	int scale_pre_decml[MAX_CHANNELS];
+	int scale_post_decml[MAX_CHANNELS];
+	int scale_precision[MAX_CHANNELS];
 	unsigned long scan_mask[2]; /* One entry plus one terminator. */
 	int num_channels;
 };
@@ -116,9 +116,12 @@ static int prox_read_raw(struct iio_dev *indio_dev,
 		ret_type = IIO_VAL_INT;
 		break;
 	case IIO_CHAN_INFO_SCALE:
-		*val = prox_state->scale_pre_decml;
-		*val2 = prox_state->scale_post_decml;
-		ret_type = prox_state->scale_precision;
+		if (chan->scan_index >= prox_state->num_channels)
+			return -EINVAL;
+
+		*val = prox_state->scale_pre_decml[chan->scan_index];
+		*val2 = prox_state->scale_post_decml[chan->scan_index];
+		ret_type = prox_state->scale_precision[chan->scan_index];
 		break;
 	case IIO_CHAN_INFO_OFFSET:
 		*val = hid_sensor_convert_exponent(
@@ -249,6 +252,10 @@ static int prox_parse_report(struct platform_device *pdev,
 					     st->prox_attr[index].size);
 		dev_dbg(&pdev->dev, "prox %x:%x\n", st->prox_attr[index].index,
 			st->prox_attr[index].report_id);
+		st->scale_precision[index] =
+			hid_sensor_format_scale(usage_id, &st->prox_attr[index],
+						&st->scale_pre_decml[index],
+						&st->scale_post_decml[index]);
 		index++;
 	}
 
@@ -257,11 +264,6 @@ static int prox_parse_report(struct platform_device *pdev,
 
 	st->num_channels = index;
 
-	st->scale_precision = hid_sensor_format_scale(hsdev->usage,
-						      &st->prox_attr[0],
-						      &st->scale_pre_decml,
-						      &st->scale_post_decml);
-
 	return 0;
 }