iio: adc: ad7192: Add update_scan_mode

The callback .set_channel cannot be used to enable multiple
channels at once, only one is allowed simultaneously.

By adding an update_scan_mode callback, every time the
continuous mode is activated, channels will be enabled/disabled
accordingly.
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Link: https://lore.kernel.org/r/20220322105029.86389-4-alexandru.tachici@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7192.c

@@ -783,6 +783,26 @@ static int ad7192_read_avail(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
+static int ad7192_update_scan_mode(struct iio_dev *indio_dev, const unsigned long *scan_mask)
+{
+	struct ad7192_state *st = iio_priv(indio_dev);
+	u32 conf = st->conf;
+	int ret;
+	int i;
+
+	conf &= ~AD7192_CONF_CHAN_MASK;
+	for_each_set_bit(i, scan_mask, 8)
+		conf |= AD7192_CONF_CHAN(i);
+
+	ret = ad_sd_write_reg(&st->sd, AD7192_REG_CONF, 3, conf);
+	if (ret < 0)
+		return ret;
+
+	st->conf = conf;
+
+	return 0;
+}
+
 static const struct iio_info ad7192_info = {
 	.read_raw = ad7192_read_raw,
 	.write_raw = ad7192_write_raw,
@@ -790,6 +810,7 @@ static const struct iio_info ad7192_info = {
 	.read_avail = ad7192_read_avail,
 	.attrs = &ad7192_attribute_group,
 	.validate_trigger = ad_sd_validate_trigger,
+	.update_scan_mode = ad7192_update_scan_mode,
 };
 
 static const struct iio_info ad7195_info = {
@@ -799,6 +820,7 @@ static const struct iio_info ad7195_info = {
 	.read_avail = ad7192_read_avail,
 	.attrs = &ad7195_attribute_group,
 	.validate_trigger = ad_sd_validate_trigger,
+	.update_scan_mode = ad7192_update_scan_mode,
 };
 
 #define __AD719x_CHANNEL(_si, _channel1, _channel2, _address, _extend_name, \