[PATCH v2 1/2] iio: adc: adi-axi-adc: add data size support for AD408X backend

[Antoniu Miclaus <antoniu.miclaus@analog.com>]

The AD408X AXI core can pack the sample data on the bus using different
word widths. Expose this through the data_size_set backend operation so
that frontends can program the packet format field (bits 3:2 of the
CNTRL_3 register) according to the ADC resolution: 20-bit, 16-bit and
14-bit map to packet format values 0, 1 and 2 respectively.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
changes in v2:
 - No changes.

 drivers/iio/adc/adi-axi-adc.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index ced0a2321ecf..aac6f4a0705e 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -54,6 +54,10 @@
 #define   AXI_AD485X_PACKET_FORMAT_24BIT	0x1
 #define   AXI_AD485X_PACKET_FORMAT_32BIT	0x2
 #define   AXI_AD408X_CNTRL_3_FILTER_EN_MSK	BIT(0)
+#define   AXI_AD408X_CNTRL_3_PACKET_FORMAT_MSK	GENMASK(3, 2)
+#define   AXI_AD408X_PACKET_FORMAT_20BIT	0x0
+#define   AXI_AD408X_PACKET_FORMAT_16BIT	0x1
+#define   AXI_AD408X_PACKET_FORMAT_14BIT	0x2
 
 #define ADI_AXI_ADC_REG_SYNC_STATUS		0x0068
 #define   ADI_AXI_ADC_SYNC_STATUS_ADC_SYNC_MSK	BIT(0)
@@ -437,6 +441,31 @@ static int axi_adc_ad408x_filter_type_set(struct iio_backend *back,
 				 AXI_AD408X_CNTRL_3_FILTER_EN_MSK);
 }
 
+static int axi_adc_ad408x_data_size_set(struct iio_backend *back,
+					unsigned int size)
+{
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
+	unsigned int val;
+
+	switch (size) {
+	case 20:
+		val = AXI_AD408X_PACKET_FORMAT_20BIT;
+		break;
+	case 16:
+		val = AXI_AD408X_PACKET_FORMAT_16BIT;
+		break;
+	case 14:
+		val = AXI_AD408X_PACKET_FORMAT_14BIT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return regmap_update_bits(st->regmap, ADI_AXI_ADC_REG_CNTRL_3,
+				  AXI_AD408X_CNTRL_3_PACKET_FORMAT_MSK,
+				  FIELD_PREP(AXI_AD408X_CNTRL_3_PACKET_FORMAT_MSK, val));
+}
+
 static int axi_adc_ad408x_interface_data_align(struct iio_backend *back,
 					       u32 timeout_us)
 {
@@ -660,6 +689,7 @@ static const struct iio_backend_ops adi_ad408x_ops = {
 	.free_buffer = axi_adc_free_buffer,
 	.data_sample_trigger = axi_adc_data_sample_trigger,
 	.filter_type_set = axi_adc_ad408x_filter_type_set,
+	.data_size_set = axi_adc_ad408x_data_size_set,
 	.interface_data_align = axi_adc_ad408x_interface_data_align,
 	.num_lanes_set = axi_adc_num_lanes_set,
 	.debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
-- 
2.43.0