Re: [PATCH] iio: hid: Add humidity sensor support

Environmental humidity sensor is a hid defined sensor,
it shows raw humidity measurement of air.

comments below
 

we want a consistent prefix, i.e. hid_humidity_

+	struct hid_sensor_common common_attributes;
+	struct hid_sensor_hub_attribute_info humidity_attr;
+	s32 humidity_data;
+	int scale_pre_decml;
+	int scale_post_decml;
+	int scale_precision;
+	int value_offset;
+};
+
+/* Channel definitions */
+static const struct iio_chan_spec humidity_channels[] = {
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
+			BIT(IIO_CHAN_INFO_SCALE) |
+			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+			BIT(IIO_CHAN_INFO_HYSTERESIS),
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(3)

should be 1

+};
+
+/* Adjust channel real bits based on report descriptor */
+static void humidity_adjust_channel_bit_mask(struct iio_chan_spec *channels,
+					int channel, int size)
+{
+	channels[channel].scan_type.sign = 's';
+	/* Real storage bits will change based on the report desc. */
+	channels[channel].scan_type.realbits = size * 8;
+	/* Maximum size of a sample to capture is s32 */
+	channels[channel].scan_type.storagebits = sizeof(s32) * 8;
+}
+
+static int humidity_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct humidity_state *humid_st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type != IIO_HUMIDITYRELATIVE)
+			return -EINVAL;
+		hid_sensor_power_state(&humid_st->common_attributes, true);
+		*val = sensor_hub_input_attr_get_raw_value(
+				humid_st->common_attributes.hsdev,
+				HID_USAGE_SENSOR_HUMIDITY,
+				HID_USAGE_SENSOR_ATMOSPHERIC_HUMIDITY,
+				humid_st->humidity_attr.report_id,
+				SENSOR_HUB_SYNC);
+		hid_sensor_power_state(&humid_st->common_attributes, false);
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = humid_st->scale_pre_decml;
+		*val2 = humid_st->scale_post_decml;
+
+		return humid_st->scale_precision;
+
+	case IIO_CHAN_INFO_OFFSET:
+		*val = humid_st->value_offset;
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return hid_sensor_read_samp_freq_value(
+				&humid_st->common_attributes, val, val2);
+
+	case IIO_CHAN_INFO_HYSTERESIS:
+		return hid_sensor_read_raw_hyst_value(
+				&humid_st->common_attributes, val, val2);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int humidity_write_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int val, int val2, long mask)
+{
+	struct humidity_state *humid_st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return hid_sensor_write_samp_freq_value(
+				&humid_st->common_attributes, val, val2);
+
+	case IIO_CHAN_INFO_HYSTERESIS:
+		return hid_sensor_write_raw_hyst_value(
+				&humid_st->common_attributes, val, val2);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info humidity_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = &humidity_read_raw,
+	.write_raw = &humidity_write_raw,
+};
+
+/* Callback handler to send event after all samples are received and captured */
+static int humidity_proc_event(struct hid_sensor_hub_device *hsdev,
+				unsigned int usage_id, void *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct humidity_state *humid_st = iio_priv(indio_dev);
+
+	if (atomic_read(&humid_st->common_attributes.data_ready))
+		iio_push_to_buffers_with_timestamp(indio_dev,
+					&humid_st->humidity_data,
+					iio_get_time_ns(indio_dev));
+
+	return 0;
+}
+
+/* Capture samples in local storage */
+static int humidity_capture_sample(struct hid_sensor_hub_device *hsdev,
+				unsigned int usage_id, size_t raw_len,
+				char *raw_data, void *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct humidity_state *humid_st = iio_priv(indio_dev);
+
+	switch (usage_id) {
+	case HID_USAGE_SENSOR_ATMOSPHERIC_HUMIDITY:
+		humid_st->humidity_data = *(s32 *)raw_data;
+
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+
+/* Parse report which is specific to an usage id*/

space missing before */

+static int humidity_parse_report(struct platform_device *pdev,
+				struct hid_sensor_hub_device *hsdev,
+				struct iio_chan_spec *channels,
+				unsigned int usage_id,
+				struct humidity_state *st)
+{
+	int ret;
+
+	ret = sensor_hub_input_get_attribute_info(hsdev, HID_INPUT_REPORT,
+					usage_id,
+					HID_USAGE_SENSOR_ATMOSPHERIC_HUMIDITY,
+					&st->humidity_attr);
+	if (ret < 0)
+		return ret;
+
+	humidity_adjust_channel_bit_mask(channels, 0, st->humidity_attr.size);
+
+	st->scale_precision = hid_sensor_format_scale(
+						HID_USAGE_SENSOR_HUMIDITY,
+						&st->humidity_attr,
+						&st->scale_pre_decml,
+						&st->scale_post_decml);
+
+	/* Set Sensitivity field ids, when there is no individual modifier */
+	if (st->common_attributes.sensitivity.index < 0)
+		sensor_hub_input_get_attribute_info(hsdev,
+			HID_FEATURE_REPORT, usage_id,
+			HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_ABS |
+			HID_USAGE_SENSOR_ATMOSPHERIC_HUMIDITY,
+			&st->common_attributes.sensitivity);
+
+	return ret;
+}
+
+static struct hid_sensor_hub_callbacks humidity_callbacks = {
+	.send_event = &humidity_proc_event,
+	.capture_sample = &humidity_capture_sample,
+};
+
+/* Function to initialize the processing for usage id */
+static int hid_humidity_probe(struct platform_device *pdev)
+{
+	static const char *name = "humidity";

most drivers use a #define and put it somewhere near the top of the code

+	struct iio_dev *indio_dev;
+	struct humidity_state *humid_st;
+	struct iio_chan_spec *humid_chans;
+	struct hid_sensor_hub_device *hsdev = dev_get_platdata(&pdev->dev);
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*humid_st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	humid_st = iio_priv(indio_dev);
+	humid_st->common_attributes.hsdev = hsdev;
+	humid_st->common_attributes.pdev = pdev;
+
+	ret = hid_sensor_parse_common_attributes(hsdev,
+					HID_USAGE_SENSOR_HUMIDITY,
+					&humid_st->common_attributes);
+	if (ret)
+		return ret;
+
+	humid_chans = devm_kmemdup(&indio_dev->dev, humidity_channels,
+					sizeof(humidity_channels), GFP_KERNEL);
+	if (!humid_chans)
+		return -ENOMEM;
+
+	ret = humidity_parse_report(pdev, hsdev, humid_chans,
+				HID_USAGE_SENSOR_HUMIDITY, humid_st);
+	if (ret)
+		return ret;
+
+	indio_dev->channels = humid_chans;
+	indio_dev->num_channels = ARRAY_SIZE(humidity_channels);
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->info = &humidity_info;
+	indio_dev->name = name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = devm_iio_triggered_buffer_setup(&pdev->dev, indio_dev,
+					&iio_pollfunc_store_time, NULL, NULL);
+	if (ret)
+		return ret;
+
+	atomic_set(&humid_st->common_attributes.data_ready, 0);
+	ret = hid_sensor_setup_trigger(indio_dev, name,
+				&humid_st->common_attributes);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	humidity_callbacks.pdev = pdev;
+	ret = sensor_hub_register_callback(hsdev, HID_USAGE_SENSOR_HUMIDITY,
+					&humidity_callbacks);
+	if (ret)
+		goto error_remove_trigger;
+
+	ret = devm_iio_device_register(indio_dev->dev.parent, indio_dev);

don't use devm_iio_device_register() if you need _remove()

-- 

Peter Meerwald-Stadler
Mobile: +43 664 24 44 418