iio: adc: mcp3911: add support to set PGA
Add support for setting the Programmable Gain Amplifiers by adjust the scale value. Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Link: https://lore.kernel.org/r/20220922194639.1118971-1-marcus.folkesson@gmail.com Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Marcus Folkesson
Jonathan Cameron
parent
4e61514036
commit
8cf5f03291
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@ -29,6 +29,8 @@
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#define MCP3911_REG_MOD 0x06
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#define MCP3911_REG_PHASE 0x07
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#define MCP3911_REG_GAIN 0x09
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#define MCP3911_GAIN_MASK(ch) (GENMASK(2, 0) << 3 * ch)
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#define MCP3911_GAIN_VAL(ch, val) ((val << 3 * ch) & MCP3911_GAIN_MASK(ch))
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#define MCP3911_REG_STATUSCOM 0x0a
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#define MCP3911_STATUSCOM_DRHIZ BIT(12)
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@ -60,8 +62,10 @@
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#define MCP3911_REG_MASK GENMASK(4, 1)
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#define MCP3911_NUM_CHANNELS 2
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#define MCP3911_NUM_SCALES 6
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static const int mcp3911_osr_table[] = { 32, 64, 128, 256, 512, 1024, 2048, 4096 };
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static u32 mcp3911_scale_table[MCP3911_NUM_SCALES][2];
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struct mcp3911 {
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struct spi_device *spi;
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@ -70,6 +74,7 @@ struct mcp3911 {
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struct clk *clki;
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u32 dev_addr;
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struct iio_trigger *trig;
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u32 gain[MCP3911_NUM_CHANNELS];
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struct {
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u32 channels[MCP3911_NUM_CHANNELS];
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s64 ts __aligned(8);
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@ -146,6 +151,11 @@ static int mcp3911_read_avail(struct iio_dev *indio_dev,
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*vals = mcp3911_osr_table;
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*length = ARRAY_SIZE(mcp3911_osr_table);
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return IIO_AVAIL_LIST;
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case IIO_CHAN_INFO_SCALE:
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*type = IIO_VAL_INT_PLUS_NANO;
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*vals = (int *)mcp3911_scale_table;
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*length = ARRAY_SIZE(mcp3911_scale_table) * 2;
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return IIO_AVAIL_LIST;
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default:
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return -EINVAL;
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}
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@ -190,29 +200,9 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
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break;
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case IIO_CHAN_INFO_SCALE:
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if (adc->vref) {
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ret = regulator_get_voltage(adc->vref);
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if (ret < 0) {
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dev_err(indio_dev->dev.parent,
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"failed to get vref voltage: %d\n",
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ret);
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goto out;
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}
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*val = ret / 1000;
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} else {
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*val = MCP3911_INT_VREF_MV;
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}
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/*
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* For 24bit Conversion
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* Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
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* Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
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*/
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/* val2 = (2^23 * 1.5) */
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*val2 = 12582912;
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ret = IIO_VAL_FRACTIONAL;
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*val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];
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*val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];
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ret = IIO_VAL_INT_PLUS_NANO;
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break;
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}
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@ -230,6 +220,18 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
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mutex_lock(&adc->lock);
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switch (mask) {
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case IIO_CHAN_INFO_SCALE:
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for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
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if (val == mcp3911_scale_table[i][0] &&
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val2 == mcp3911_scale_table[i][1]) {
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adc->gain[channel->channel] = BIT(i);
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ret = mcp3911_update(adc, MCP3911_REG_GAIN,
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MCP3911_GAIN_MASK(channel->channel),
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MCP3911_GAIN_VAL(channel->channel, i), 1);
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}
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}
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break;
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case IIO_CHAN_INFO_OFFSET:
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if (val2 != 0) {
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ret = -EINVAL;
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@ -265,6 +267,44 @@ out:
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return ret;
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}
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static int mcp3911_calc_scale_table(struct mcp3911 *adc)
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{
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u32 ref = MCP3911_INT_VREF_MV;
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u32 div;
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int ret;
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u64 tmp;
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if (adc->vref) {
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ret = regulator_get_voltage(adc->vref);
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if (ret < 0) {
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dev_err(&adc->spi->dev,
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"failed to get vref voltage: %d\n",
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ret);
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return ret;
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}
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ref = ret / 1000;
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}
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/*
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* For 24-bit Conversion
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* Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5
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* Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)
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*
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* ref = Reference voltage
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* div = (2^23 * 1.5 * gain) = 12582912 * gain
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*/
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for (int i = 0; i < MCP3911_NUM_SCALES; i++) {
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div = 12582912 * BIT(i);
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tmp = div_s64((s64)ref * 1000000000LL, div);
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mcp3911_scale_table[i][0] = 0;
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mcp3911_scale_table[i][1] = tmp;
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}
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return 0;
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}
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#define MCP3911_CHAN(idx) { \
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.type = IIO_VOLTAGE, \
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.indexed = 1, \
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@ -274,8 +314,10 @@ out:
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
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BIT(IIO_CHAN_INFO_OFFSET) | \
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BIT(IIO_CHAN_INFO_SCALE), \
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.info_mask_shared_by_type_available = \
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.info_mask_shared_by_type_available = \
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BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
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.info_mask_separate_available = \
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BIT(IIO_CHAN_INFO_SCALE), \
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.scan_type = { \
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.sign = 's', \
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.realbits = 24, \
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@ -482,6 +524,20 @@ static int mcp3911_probe(struct spi_device *spi)
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if (ret)
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return ret;
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ret = mcp3911_calc_scale_table(adc);
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if (ret)
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return ret;
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/* Set gain to 1 for all channels */
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for (int i = 0; i < MCP3911_NUM_CHANNELS; i++) {
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adc->gain[i] = 1;
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ret = mcp3911_update(adc, MCP3911_REG_GAIN,
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MCP3911_GAIN_MASK(i),
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MCP3911_GAIN_VAL(i, 0), 1);
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if (ret)
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return ret;
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}
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indio_dev->name = spi_get_device_id(spi)->name;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->info = &mcp3911_info;
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