[PATCH 06/10] iio: adc: mcp3911: add support for oversampling ratio

[Marcus Folkesson <marcus.folkesson@xxxxxxxxx>]

The chip support oversampling ratio so expose it to userspace.

Signed-off-by: Marcus Folkesson <marcus.folkesson@xxxxxxxxx>
---
 drivers/iio/adc/mcp3911.c | 72 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index e761feed5303..65831bef12f6 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -5,6 +5,8 @@
  * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@xxxxxxxxx>
  * Copyright (C) 2018 Kent Gustavsson <kent@xxxxxxxxxx>
  */
+#include <linux/bitfield.h>
+#include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
@@ -35,6 +37,7 @@
 #define MCP3911_REG_CONFIG		0x0c
 #define MCP3911_CONFIG_CLKEXT		BIT(1)
 #define MCP3911_CONFIG_VREFEXT		BIT(2)
+#define MCP3911_CONFIG_OSR		GENMASK(13, 11)
 
 #define MCP3911_REG_OFFCAL_CH0		0x0e
 #define MCP3911_REG_GAINCAL_CH0		0x11
@@ -53,6 +56,8 @@
 
 #define MCP3911_NUM_CHANNELS		2
 
+static const int mcp3911_osr_table[] = {32, 64, 128, 256, 512, 1024, 2048, 4096};
+
 struct mcp3911 {
 	struct spi_device *spi;
 	struct mutex lock;
@@ -108,6 +113,22 @@ static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
 	return mcp3911_write(adc, reg, val, len);
 }
 
+
+static int mcp3911_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     const int **vals, int *type, int *length,
+			     long info)
+{
+	switch (info) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*type = IIO_VAL_INT;
+		*vals = mcp3911_osr_table;
+		*length = ARRAY_SIZE(mcp3911_osr_table);
+		return IIO_AVAIL_LIST;
+	default:
+		return -EINVAL;
+	}
+}
 static int mcp3911_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *channel, int *val,
 			    int *val2, long mask)
@@ -134,6 +155,16 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
 
 		ret = IIO_VAL_INT;
 		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		ret = mcp3911_read(adc,
+				MCP3911_REG_CONFIG, val, 2);
+		if (ret)
+			goto out;
+
+		*val = FIELD_GET(MCP3911_CONFIG_OSR, *val);
+		*val = 32 << *val;
+		ret = IIO_VAL_INT;
+		break;
 
 	case IIO_CHAN_INFO_SCALE:
 		if (adc->vref) {
@@ -186,6 +217,42 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
 				MCP3911_STATUSCOM_EN_OFFCAL,
 				MCP3911_STATUSCOM_EN_OFFCAL, 2);
 		break;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		switch (val) {
+		case 4096:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x07);
+			break;
+		case 2048:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x06);
+			break;
+		case 1024:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x05);
+			break;
+		case 512:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x04);
+			break;
+		case 256:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x03);
+			break;
+		case 128:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x02);
+			break;
+		case 64:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x01);
+			break;
+		case 32:
+			val = FIELD_PREP(MCP3911_CONFIG_OSR, 0x00);
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = mcp3911_update(adc, MCP3911_REG_CONFIG,
+				MCP3911_CONFIG_OSR,
+				val, 2);
+		break;
 	}
 
 out:
@@ -198,9 +265,13 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
 		.indexed = 1,					\
 		.channel = idx,					\
 		.scan_index = idx,				\
+		.scan_index = idx,				\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |	\
 			BIT(IIO_CHAN_INFO_OFFSET) |		\
 			BIT(IIO_CHAN_INFO_SCALE),		\
+		.info_mask_shared_by_type_available =		\
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
 		.scan_type = {					\
 			.sign = 's',				\
 			.realbits = 24,				\
@@ -252,6 +323,7 @@ static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
 static const struct iio_info mcp3911_info = {
 	.read_raw = mcp3911_read_raw,
 	.write_raw = mcp3911_write_raw,
+	.read_avail = mcp3911_read_avail,
 };
 
 static irqreturn_t mcp3911_interrupt(int irq, void *dev_id)
-- 
2.36.1