iio: dac: adi-axi-dac: add data source get

Add data source getter.

Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Signed-off-by: Angelo Dureghello <adureghello@baylibre.com>
Link: https://patch.msgid.link/20250409-wip-bl-ad3552r-fixes-v5-4-fb429c3a6515@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: spectrum70

drivers/iio/dac/adi-axi-dac.c

@@ -536,6 +536,35 @@ static int axi_dac_data_source_set(struct iio_backend *back, unsigned int chan,
 	}
 }
 
+static int axi_dac_data_source_get(struct iio_backend *back, unsigned int chan,
+				   enum iio_backend_data_source *data)
+{
+	struct axi_dac_state *st = iio_backend_get_priv(back);
+	int ret;
+	u32 val;
+
+	if (chan > AXI_DAC_CHAN_CNTRL_MAX)
+		return -EINVAL;
+
+	ret = regmap_read(st->regmap, AXI_DAC_CHAN_CNTRL_7_REG(chan), &val);
+	if (ret)
+		return ret;
+
+	switch (val) {
+	case AXI_DAC_DATA_INTERNAL_TONE:
+		*data = IIO_BACKEND_INTERNAL_CONTINUOUS_WAVE;
+		return 0;
+	case AXI_DAC_DATA_DMA:
+		*data = IIO_BACKEND_EXTERNAL;
+		return 0;
+	case AXI_DAC_DATA_INTERNAL_RAMP_16BIT:
+		*data = IIO_BACKEND_INTERNAL_RAMP_16BIT;
+		return 0;
+	default:
+		return -EIO;
+	}
+}
+
 static int axi_dac_set_sample_rate(struct iio_backend *back, unsigned int chan,
 				   u64 sample_rate)
 {
@@ -815,6 +844,7 @@ static const struct iio_backend_ops axi_ad3552r_ops = {
 	.request_buffer = axi_dac_request_buffer,
 	.free_buffer = axi_dac_free_buffer,
 	.data_source_set = axi_dac_data_source_set,
+	.data_source_get = axi_dac_data_source_get,
 	.ddr_enable = axi_dac_ddr_enable,
 	.ddr_disable = axi_dac_ddr_disable,
 	.data_stream_enable = axi_dac_data_stream_enable,