Am 05.03.2017 um 13:08 schrieb Jonathan Cameron:
> On 04/03/17 16:29, Heiner Kallweit wrote:
>> The calibration on Meson GXBB is different from the one on GXM/GXL.
>> This patch only supports GXBB as I don't have other spec and test hw.
>> Points 25% vref and 75% vref are used for calibration.
>>
>> Adding a calibration scale resulted in no improvement, therefore
>> only a simple calibration bias is supported.
> You probably want to update this description ;)
Uups, yes .. Will wait for Martin's feedback and send a v3 with
at least a updated commit message.
>>
>> Successfully tested on a Odroid C2. Calibbias is 8 on my system.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
>> ---
> Looks good to me. Will want Martin's Ack on this, so I'll wait for that
> before applying.
>
> Jonathan
>> v2:
>> - added calibration scale
>> ---
>> drivers/iio/adc/meson_saradc.c | 74 ++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 72 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
>> index 23710088..d5aa0d04 100644
>> --- a/drivers/iio/adc/meson_saradc.c
>> +++ b/drivers/iio/adc/meson_saradc.c
>> @@ -173,7 +173,9 @@
>> .channel = _chan, \
>> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
>> BIT(IIO_CHAN_INFO_AVERAGE_RAW), \
>> - .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
>> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \
>> + BIT(IIO_CHAN_INFO_CALIBBIAS) | \
>> + BIT(IIO_CHAN_INFO_CALIBSCALE), \
>> .datasheet_name = "SAR_ADC_CH"#_chan, \
>> }
>>
>> @@ -233,6 +235,8 @@ struct meson_sar_adc_priv {
>> struct clk *adc_div_clk;
>> struct clk_divider clk_div;
>> struct completion done;
>> + int calibbias;
>> + int calibscale;
>> };
>>
>> static const struct regmap_config meson_sar_adc_regmap_config = {
>> @@ -252,6 +256,16 @@ static unsigned int meson_sar_adc_get_fifo_count(struct iio_dev *indio_dev)
>> return FIELD_GET(MESON_SAR_ADC_REG0_FIFO_COUNT_MASK, regval);
>> }
>>
>> +static int meson_sar_adc_calib_val(struct iio_dev *indio_dev, int val)
>> +{
>> + struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
>> + int tmp;
>> +
>> + tmp = div_s64((s64)val * priv->calibscale, 1000000) + priv->calibbias;
>> +
>> + return clamp(tmp, 0, (1 << priv->data->resolution) - 1);
>> +}
>> +
>> static int meson_sar_adc_wait_busy_clear(struct iio_dev *indio_dev)
>> {
>> struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
>> @@ -303,7 +317,7 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
>> fifo_val = FIELD_GET(MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK,
>> regval);
>> fifo_val &= GENMASK(priv->data->resolution - 1, 0);
>> - *val = fifo_val;
>> + *val = meson_sar_adc_calib_val(indio_dev, fifo_val);
>>
>> return 0;
>> }
>> @@ -529,6 +543,15 @@ static int meson_sar_adc_iio_info_read_raw(struct iio_dev *indio_dev,
>> *val2 = priv->data->resolution;
>> return IIO_VAL_FRACTIONAL_LOG2;
>>
>> + case IIO_CHAN_INFO_CALIBBIAS:
>> + *val = priv->calibbias;
>> + return IIO_VAL_INT;
>> +
>> + case IIO_CHAN_INFO_CALIBSCALE:
>> + *val = priv->calibscale / 1000000;
>> + *val2 = priv->calibscale % 1000000;
>> + return IIO_VAL_INT_PLUS_MICRO;
>> +
>> default:
>> return -EINVAL;
>> }
>> @@ -754,6 +777,47 @@ static irqreturn_t meson_sar_adc_irq(int irq, void *data)
>> return IRQ_HANDLED;
>> }
>>
>> +static int meson_sar_adc_calib(struct iio_dev *indio_dev)
>> +{
>> + struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
>> + int ret, nominal0, nominal1, value0, value1;
>> +
>> + /* use points 25% and 75% for calibration */
>> + nominal0 = (1 << priv->data->resolution) / 4;
>> + nominal1 = (1 << priv->data->resolution) * 3 / 4;
>> +
>> + meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_VDD_DIV4);
>> + usleep_range(10, 20);
>> + ret = meson_sar_adc_get_sample(indio_dev,
>> + &meson_sar_adc_iio_channels[7],
>> + MEAN_AVERAGING, EIGHT_SAMPLES, &value0);
>> + if (ret < 0)
>> + goto out;
>> +
>> + meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_VDD_MUL3_DIV4);
>> + usleep_range(10, 20);
>> + ret = meson_sar_adc_get_sample(indio_dev,
>> + &meson_sar_adc_iio_channels[7],
>> + MEAN_AVERAGING, EIGHT_SAMPLES, &value1);
>> + if (ret < 0)
>> + goto out;
>> +
>> + if (value1 <= value0) {
>> + ret = -EINVAL;
>> + goto out;
>> + }
>> +
>> + priv->calibscale = div_s64((nominal1 - nominal0) * 1000000LL,
>> + value1 - value0);
>> + priv->calibbias = nominal0 - div_s64((s64)value0 * priv->calibscale,
>> + 1000000);
>> + ret = 0;
>> +out:
>> + meson_sar_adc_set_chan7_mux(indio_dev, CHAN7_MUX_CH7_INPUT);
>> +
>> + return ret;
>> +}
>> +
>> static const struct iio_info meson_sar_adc_iio_info = {
>> .read_raw = meson_sar_adc_iio_info_read_raw,
>> .driver_module = THIS_MODULE,
>> @@ -893,6 +957,8 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
>> return PTR_ERR(priv->vref);
>> }
>>
>> + priv->calibscale = 1000000;
>> +
>> ret = meson_sar_adc_init(indio_dev);
>> if (ret)
>> goto err;
>> @@ -901,6 +967,10 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
>> if (ret)
>> goto err;
>>
>> + ret = meson_sar_adc_calib(indio_dev);
>> + if (ret)
>> + goto err_hw;
>> +
>> platform_set_drvdata(pdev, indio_dev);
>>
>> ret = iio_device_register(indio_dev);
>>
>
>
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