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    Subject[PATCH v2 10/10] iio: adc: mcp3911: add support to set PGA
    Date
    Add support for setting the Programmable Gain Amplifiers by adjust the
    scale value.

    Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
    ---

    Notes:
    v2:
    - add missing comma
    - Address comments from Andy Shevchenko

    drivers/iio/adc/mcp3911.c | 134 +++++++++++++++++++++++++++++++-------
    1 file changed, 110 insertions(+), 24 deletions(-)

    diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
    index a019264e73e3..f0179385485f 100644
    --- a/drivers/iio/adc/mcp3911.c
    +++ b/drivers/iio/adc/mcp3911.c
    @@ -26,6 +26,8 @@
    #define MCP3911_REG_MOD 0x06
    #define MCP3911_REG_PHASE 0x07
    #define MCP3911_REG_GAIN 0x09
    +#define MCP3911_GAIN_MASK(ch) (0x7 << 3*ch)
    +#define MCP3911_GAIN_VAL(ch, val) ((val << 3*ch) & MCP3911_GAIN_MASK(ch))

    #define MCP3911_REG_STATUSCOM 0x0a
    #define MCP3911_STATUSCOM_DRHIZ BIT(12)
    @@ -55,8 +57,10 @@
    #define MCP3911_REG_WRITE(reg, id) ((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)

    #define MCP3911_NUM_CHANNELS 2
    +#define MCP3911_NUM_SCALES 6

    static const int mcp3911_osr_table[] = {32, 64, 128, 256, 512, 1024, 2048, 4096};
    +static u32 mcp3911_scale_table[MCP3911_NUM_SCALES][2];

    struct mcp3911 {
    struct spi_device *spi;
    @@ -65,6 +69,7 @@ struct mcp3911 {
    struct clk *clki;
    u32 dev_addr;
    struct iio_trigger *trig;
    + u32 gain[MCP3911_NUM_CHANNELS];
    struct {
    u32 channels[2];
    s64 ts __aligned(8);
    @@ -113,6 +118,37 @@ static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
    return mcp3911_write(adc, reg, val, len);
    }

    +static int mcp3911_get_gain(struct mcp3911 *adc, u8 channel, u32 *val)
    +{
    + int ret;
    +
    + ret = mcp3911_read(adc, MCP3911_REG_GAIN, val, 1);
    + if (ret)
    + return ret;
    +
    + *val >>= channel * 3;
    + *val &= GENMASK(2, 0);
    + *val = BIT(*val);
    +
    + return 0;
    +}
    +
    +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;
    + case IIO_CHAN_INFO_PHASE:
    + 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,
    @@ -124,6 +160,11 @@ static int mcp3911_read_avail(struct iio_dev *indio_dev,
    *vals = mcp3911_osr_table;
    *length = ARRAY_SIZE(mcp3911_osr_table);
    return IIO_AVAIL_LIST;
    + case IIO_CHAN_INFO_SCALE:
    + *type = IIO_VAL_INT_PLUS_NANO;
    + *vals = (int *)mcp3911_scale_table;
    + *length = ARRAY_SIZE(mcp3911_scale_table) * 2;
    + return IIO_AVAIL_LIST;
    default:
    return -EINVAL;
    }
    @@ -180,29 +221,9 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
    break;

    case IIO_CHAN_INFO_SCALE:
    - if (adc->vref) {
    - ret = regulator_get_voltage(adc->vref);
    - if (ret < 0) {
    - dev_err(indio_dev->dev.parent,
    - "failed to get vref voltage: %d\n",
    - ret);
    - goto out;
    - }
    -
    - *val = ret / 1000;
    - } else {
    - *val = MCP3911_INT_VREF_MV;
    - }
    -
    - /*
    - * For 24bit Conversion
    - * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
    - * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
    - */
    -
    - /* val2 = (2^23 * 1.5) */
    - *val2 = 12582912;
    - ret = IIO_VAL_FRACTIONAL;
    + *val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
    + *val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
    + ret = IIO_VAL_INT_PLUS_NANO;
    break;
    }

    @@ -220,6 +241,18 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,

    mutex_lock(&adc->lock);
    switch (mask) {
    + case IIO_CHAN_INFO_SCALE:
    + for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
    + if (val == mcp3911_scale_table[i][0] &&
    + val2 == mcp3911_scale_table[i][1]) {
    +
    + adc->gain[channel->channel] = BIT(i);
    + ret = mcp3911_update(adc, MCP3911_REG_GAIN,
    + MCP3911_GAIN_MASK(channel->channel),
    + MCP3911_GAIN_VAL(channel->channel, i), 1);
    + }
    + }
    + break;
    case IIO_CHAN_INFO_OFFSET:
    if (val2 != 0) {
    ret = -EINVAL;
    @@ -264,6 +297,48 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
    return ret;
    }

    +static int mcp3911_calc_scale_table(struct mcp3911 *adc)
    +{
    + u32 ref = MCP3911_INT_VREF_MV;
    + u32 div;
    + int ret;
    + int tmp0, tmp1;
    + s64 tmp2;
    +
    + if (adc->vref) {
    + ret = regulator_get_voltage(adc->vref);
    + if (ret < 0) {
    + dev_err(&adc->spi->dev,
    + "failed to get vref voltage: %d\n",
    + ret);
    + return ret;
    + }
    +
    + ref = ret / 1000;
    + }
    +
    + /*
    + * For 24bit Conversion
    + * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
    + * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
    + */
    +
    + /* ref = Reference voltage
    + * div = (2^23 * 1.5 * gain) = 12582912 * gain
    + */
    + for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
    + div = 12582912 * BIT(i);
    + tmp2 = div_s64((s64)ref * 1000000000LL, div);
    + tmp1 = div;
    + tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
    +
    + mcp3911_scale_table[i][0] = 0;
    + mcp3911_scale_table[i][1] = tmp1;
    + }
    +
    + return 0;
    +}
    +
    #define MCP3911_CHAN(idx) { \
    .type = IIO_VOLTAGE, \
    .indexed = 1, \
    @@ -276,8 +351,10 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
    .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
    BIT(IIO_CHAN_INFO_OFFSET) | \
    BIT(IIO_CHAN_INFO_SCALE), \
    - .info_mask_shared_by_type_available = \
    + .info_mask_shared_by_type_available = \
    BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
    + .info_mask_separate_available = \
    + BIT(IIO_CHAN_INFO_SCALE), \
    .scan_type = { \
    .sign = 's', \
    .realbits = 24, \
    @@ -330,6 +407,7 @@ 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 irqreturn_t mcp3911_interrupt(int irq, void *dev_id)
    @@ -460,6 +538,14 @@ static int mcp3911_probe(struct spi_device *spi)
    if (ret)
    goto clk_disable;

    + ret = mcp3911_calc_scale_table(adc);
    + if (ret)
    + goto clk_disable;
    +
    + /* Store gain values to better calculate scale values */
    + mcp3911_get_gain(adc, 0, &adc->gain[0]);
    + mcp3911_get_gain(adc, 1, &adc->gain[1]);
    +
    if (device_property_read_bool(&adc->spi->dev, "microchip,data-ready-hiz"))
    ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM, MCP3911_STATUSCOM_DRHIZ,
    0, 2);
    --
    2.36.1
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      Last update: 2022-06-25 12:40    [W:3.453 / U:0.024 seconds]
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