staging:iio: dummy driver additions to show shared_by_dir infomask usage

Note that as this driver has output as well as output channels an
example of info_mask_shared_by_all that makes any sense does not exist.
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>

drivers/staging/iio/iio_simple_dummy.c

@@ -90,6 +90,11 @@ static const struct iio_chan_spec iio_dummy_channels[] = {
 		 * when converting to standard units (microvolts)
 		 */
 		BIT(IIO_CHAN_INFO_SCALE),
+		/*
+		 * sampling_frequency
+		 * The frequency in Hz at which the channels are sampled
+		 */
+		.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		/* The ordering of elements in the buffer via an enum */
 		.scan_index = voltage0,
 		.scan_type = { /* Description of storage in buffer */
@@ -130,6 +135,10 @@ static const struct iio_chan_spec iio_dummy_channels[] = {
 		 * input channels of type IIO_VOLTAGE.
 		 */
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		/*
+		 * sampling_frequency
+		 * The frequency in Hz at which the channels are sampled
+		 */
 		.scan_index = diffvoltage1m2,
 		.scan_type = { /* Description of storage in buffer */
 			.sign = 's', /* signed */
@@ -147,6 +156,7 @@ static const struct iio_chan_spec iio_dummy_channels[] = {
 		.channel2 = 4,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		.scan_index = diffvoltage3m4,
 		.scan_type = {
 			.sign = 's',
@@ -173,6 +183,7 @@ static const struct iio_chan_spec iio_dummy_channels[] = {
 		 */
 		BIT(IIO_CHAN_INFO_CALIBSCALE) |
 		BIT(IIO_CHAN_INFO_CALIBBIAS),
+		.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		.scan_index = accelx,
 		.scan_type = { /* Description of storage in buffer */
 			.sign = 's', /* signed */
@@ -272,6 +283,11 @@ static int iio_dummy_read_raw(struct iio_dev *indio_dev,
 		*val2 = st->accel_calibscale->val2;
 		ret = IIO_VAL_INT_PLUS_MICRO;
 		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = 3;
+		*val2 = 33;
+		ret = IIO_VAL_INT_PLUS_NANO;
+		break;
 	default:
 		break;
 	}