iio:adc:ad799x: Allow writing of event config

Allows explicity enabling of events

Previously, events were always reported as enabled, but actually only
implicitly enabled when updating the buffer scan mode
Signed-off-by: NPeter Meerwald <pmeerw@pmeerw.net>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/adc/ad799x.c

@@ -375,6 +375,39 @@ static int ad799x_read_event_config(struct iio_dev *indio_dev,
 	return 0;
 }
 
+static int ad799x_write_event_config(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir,
+				     int state)
+{
+	struct ad799x_state *st = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&indio_dev->mlock);
+	if (iio_buffer_enabled(indio_dev)) {
+		ret = -EBUSY;
+		goto done;
+	}
+
+	if (state)
+		st->config |= BIT(chan->scan_index) << AD799X_CHANNEL_SHIFT;
+	else
+		st->config &= ~(BIT(chan->scan_index) << AD799X_CHANNEL_SHIFT);
+
+	if (st->config >> AD799X_CHANNEL_SHIFT)
+		st->config |= AD7998_ALERT_EN;
+	else
+		st->config &= ~AD7998_ALERT_EN;
+
+	ret = ad799x_write_config(st, st->config);
+
+done:
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret;
+}
+
 static unsigned int ad799x_threshold_reg(const struct iio_chan_spec *chan,
 					 enum iio_event_direction dir,
 					 enum iio_event_info info)
@@ -502,6 +535,7 @@ static const struct iio_info ad7993_4_7_8_irq_info = {
 	.read_raw = &ad799x_read_raw,
 	.event_attrs = &ad799x_event_attrs_group,
 	.read_event_config = &ad799x_read_event_config,
+	.write_event_config = &ad799x_write_event_config,
 	.read_event_value = &ad799x_read_event_value,
 	.write_event_value = &ad799x_write_event_value,
 	.driver_module = THIS_MODULE,