linux-kernel - [PATCH v3 8/9] iio: adc: mcp3911: add support for oversampling ratio

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Message-Id: <20220704172116.195841-9-marcus.folkesson@gmail.com>
Date:   Mon,  4 Jul 2022 19:21:15 +0200
From:   Marcus Folkesson <marcus.folkesson@...il.com>
To:     Marcus Folkesson <marcus.folkesson@...il.com>,
        Kent Gustavsson <kent@...oris.se>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 8/9] iio: adc: mcp3911: add support for oversampling ratio

The chip supports oversampling ratio, so expose it to userspace.

Signed-off-by: Marcus Folkesson <marcus.folkesson@...il.com>
---
 drivers/iio/adc/mcp3911.c | 59 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index 9c6f456bdbdf..c6e30471bb81 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -38,6 +38,7 @@
 #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
@@ -56,6 +57,8 @@
 
 #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;
@@ -114,6 +117,36 @@ static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
 	return mcp3911_write(adc, reg, val, len);
 }
 
+static int mcp3911_write_raw_get_fmt(struct iio_dev *indio_dev,
+					struct iio_chan_spec const *chan,
+					long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		return IIO_VAL_INT;
+	default:
+		return IIO_VAL_INT_PLUS_NANO;
+	}
+}
+
+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)
@@ -142,6 +175,16 @@ 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) {
@@ -201,6 +244,17 @@ 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:
+		for (int i = 0; i < sizeof(mcp3911_osr_table); i++) {
+			if (val == mcp3911_osr_table[i]) {
+				val = FIELD_PREP(MCP3911_CONFIG_OSR, i);
+				ret = mcp3911_update(adc, MCP3911_REG_CONFIG, MCP3911_CONFIG_OSR,
+						val, 2);
+				break;
+			}
+		}
+		break;
 	}
 
 out:
@@ -213,9 +267,12 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
 		.indexed = 1,					\
 		.channel = 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,				\
@@ -275,6 +332,8 @@ 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,
+	.write_raw_get_fmt = mcp3911_write_raw_get_fmt,
 };
 
 static int mcp3911_config(struct mcp3911 *adc)
-- 
2.36.1