iio: adc: ad9467: support write/read offset via _calibbias

Support configuring output calibration value. Among the devices
currently supported by this driver, this setting is specific to
ad9434. The offset can be used to calibrate the output against
a known input. The register is called offset, but the procedure
is best mapped internally with calibbias operation.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
index f7a9f46ea0dc405e25f312197df4b2131871b4bc..995d811d4fbe4f915540ca38bec7afc7e2560c11 100644 (file)
--- a/drivers/iio/adc/ad9467.c
+++ b/drivers/iio/adc/ad9467.c
@@ -145,6 +145,7 @@ struct ad9467_chip_info {
        unsigned int num_lanes;
        unsigned int dco_en;
        unsigned int test_points;
+       const int *offset_range;
        /* data clock output */
        bool has_dco;
        bool has_dco_invert;
@@ -234,6 +235,10 @@ static int ad9467_reg_access(struct iio_dev *indio_dev, unsigned int reg,
        return 0;
 }
 
+static const int ad9434_offset_range[] = {
+       -128, 1, 127,
+};
+
 static const unsigned int ad9265_scale_table[][2] = {
        {1250, 0x00}, {1500, 0x40}, {1750, 0x80}, {2000, 0xC0},
 };
@@ -298,7 +303,24 @@ static void __ad9467_get_scale(struct ad9467_state *st, int index,
 }
 
 static const struct iio_chan_spec ad9434_channels[] = {
-       AD9467_CHAN(0, BIT(IIO_CHAN_INFO_SCALE), 0, 12, 's'),
+       {
+               .type = IIO_VOLTAGE,
+               .indexed = 1,
+               .channel = 0,
+               .info_mask_shared_by_type =
+                       BIT(IIO_CHAN_INFO_SCALE) |
+                       BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+                       BIT(IIO_CHAN_INFO_CALIBBIAS),
+               .info_mask_shared_by_type_available =
+                       BIT(IIO_CHAN_INFO_SCALE) |
+                       BIT(IIO_CHAN_INFO_CALIBBIAS),
+               .scan_index = 0,
+               .scan_type = {
+                       .sign = 's',
+                       .realbits = 12,
+                       .storagebits = 16,
+               },
+       },
 };
 
 static const struct iio_chan_spec ad9467_channels[] = {
@@ -367,6 +389,7 @@ static const struct ad9467_chip_info ad9434_chip_tbl = {
        .default_output_mode = AD9434_DEF_OUTPUT_MODE,
        .vref_mask = AD9434_REG_VREF_MASK,
        .num_lanes = 6,
+       .offset_range = ad9434_offset_range,
 };
 
 static const struct ad9467_chip_info ad9265_chip_tbl = {
@@ -499,6 +522,33 @@ static int ad9467_set_scale(struct ad9467_state *st, int val, int val2)
        return -EINVAL;
 }
 
+static int ad9467_get_offset(struct ad9467_state *st, int *val)
+{
+       int ret;
+
+       ret = ad9467_spi_read(st, AN877_ADC_REG_OFFSET);
+       if (ret < 0)
+               return ret;
+       *val = ret;
+
+       return IIO_VAL_INT;
+}
+
+static int ad9467_set_offset(struct ad9467_state *st, int val)
+{
+       int ret;
+
+       if (val < st->info->offset_range[0] || val > st->info->offset_range[2])
+               return -EINVAL;
+
+       ret = ad9467_spi_write(st, AN877_ADC_REG_OFFSET, val);
+       if (ret < 0)
+               return ret;
+
+       return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
+                               AN877_ADC_TRANSFER_SYNC);
+}
+
 static int ad9467_outputmode_set(struct ad9467_state *st, unsigned int mode)
 {
        int ret;
@@ -802,6 +852,8 @@ static int ad9467_read_raw(struct iio_dev *indio_dev,
        struct ad9467_state *st = iio_priv(indio_dev);
 
        switch (m) {
+       case IIO_CHAN_INFO_CALIBBIAS:
+               return ad9467_get_offset(st, val);
        case IIO_CHAN_INFO_SCALE:
                return ad9467_get_scale(st, val, val2);
        case IIO_CHAN_INFO_SAMP_FREQ:
@@ -836,6 +888,8 @@ static int ad9467_write_raw(struct iio_dev *indio_dev,
        int ret;
 
        switch (mask) {
+       case IIO_CHAN_INFO_CALIBBIAS:
+               return ad9467_set_offset(st, val);
        case IIO_CHAN_INFO_SCALE:
                return ad9467_set_scale(st, val, val2);
        case IIO_CHAN_INFO_SAMP_FREQ:
@@ -874,6 +928,10 @@ static int ad9467_read_avail(struct iio_dev *indio_dev,
        const struct ad9467_chip_info *info = st->info;
 
        switch (mask) {
+       case IIO_CHAN_INFO_CALIBBIAS:
+               *type = IIO_VAL_INT;
+               *vals = info->offset_range;
+               return IIO_AVAIL_RANGE;
        case IIO_CHAN_INFO_SCALE:
                *vals = (const int *)st->scales;
                *type = IIO_VAL_INT_PLUS_MICRO;