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@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220815061625.35568-9-marcus.folkesson@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index 4e45ccc..b35fd2c 100644 (file)
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -41,6 +41,7 @@
 #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
@@ -59,6 +60,8 @@
 
 #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;
@@ -117,6 +120,36 @@ 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)
@@ -145,6 +178,15 @@ 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) {
@@ -204,6 +246,17 @@ 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:
@@ -216,9 +269,12 @@ out:
                .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,                         \
@@ -278,6 +334,8 @@ out:
 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)