> The mxs LRADC is able to read an internal die temperature sensor. The
> temperature has to be calculated from the value read on channel 8 and channel 9.
> To be able to expose the result to hwmon, implement iio channel 8 as
> (channel 9 - channel 8). Then, implement IIO_CHAN_INFO_SCALE and
> IIO_CHAN_INFO_OFFSET so that it can be processed by hwmon through the in kernel
> provider/consumer mechanism.
wouldn't IIO_CHAN_INFO_PROCESSED be more suitable than IIO_CHAN_INFO_RAW?
> Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> ---
> drivers/staging/iio/adc/mxs-lradc.c | 91 +++++++++++++++++++++++++++++++------
> 1 file changed, 78 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c
> index a08c1736458b..fec76090dae5 100644
> --- a/drivers/staging/iio/adc/mxs-lradc.c
> +++ b/drivers/staging/iio/adc/mxs-lradc.c
> @@ -231,20 +231,11 @@ struct mxs_lradc {
> /*
> * Raw I/O operations
> */
> -static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
> - const struct iio_chan_spec *chan,
> - int *val, int *val2, long m)
> +static int mxs_lradc_read_single(struct iio_dev *iio_dev, int chan, int *val)
> {
> struct mxs_lradc *lradc = iio_priv(iio_dev);
> int ret;
>
> - if (m != IIO_CHAN_INFO_RAW)
> - return -EINVAL;
> -
> - /* Check for invalid channel */
> - if (chan->channel > LRADC_MAX_TOTAL_CHANS)
> - return -EINVAL;
> -
> /*
> * See if there is no buffered operation in progess. If there is, simply
> * bail out. This can be improved to support both buffered and raw IO at
> @@ -269,7 +260,7 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
> /* Clean the slot's previous content, then set new one. */
> writel(LRADC_CTRL4_LRADCSELECT_MASK(0),
> lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
> - writel(chan->channel, lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
> + writel(chan, lradc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
>
> writel(0, lradc->base + LRADC_CH(0));
>
> @@ -298,6 +289,71 @@ err:
> return ret;
> }
>
> +static int mxs_lradc_read_temp(struct iio_dev *iio_dev, int *val)
> +{
> + int ret, min, max;
> +
> + ret = mxs_lradc_read_single(iio_dev, 8, &min);
> + if (ret != IIO_VAL_INT)
> + return ret;
> +
> + ret = mxs_lradc_read_single(iio_dev, 9, &max);
> + if (ret != IIO_VAL_INT)
> + return ret;
> +
> + *val = max - min;
> +
> + return IIO_VAL_INT;
> +}
> +
> +static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
> + const struct iio_chan_spec *chan,
> + int *val, int *val2, long m)
> +{
> + /* Check for invalid channel */
> + if (chan->channel > LRADC_MAX_TOTAL_CHANS)
> + return -EINVAL;
> +
> + switch (m) {
> + case IIO_CHAN_INFO_RAW:
> + if (chan->type == IIO_TEMP)
> + return mxs_lradc_read_temp(iio_dev, val);
> +
> + return mxs_lradc_read_single(iio_dev, chan->channel, val);
> +
> + case IIO_CHAN_INFO_SCALE:
> + if (chan->type == IIO_TEMP) {
> + /* From the datasheet, we have to multiply by 1.012 and
> + * divide by 4
> + */
> + *val = 0;
> + *val2 = 253000;
> + return IIO_VAL_INT_PLUS_MICRO;
> + }
> +
> + return -EINVAL;
> +
> + case IIO_CHAN_INFO_OFFSET:
> + if (chan->type == IIO_TEMP) {
> + /* The calculated value from the ADC is in Kelvin, we
> + * want Celsius for hwmon so the offset is
> + * -272.15 * scale
> + */
> + *val = -1075;
> + *val2 = 691699;
> +
> + return IIO_VAL_INT_PLUS_MICRO;
> + }
> +
> + return -EINVAL;
> +
> + default:
> + break;
> + }
> +
> + return -EINVAL;
> +}
> +
> static const struct iio_info mxs_lradc_iio_info = {
> .driver_module = THIS_MODULE,
> .read_raw = mxs_lradc_read_raw,
> @@ -835,8 +891,17 @@ static const struct iio_chan_spec mxs_lradc_chan_spec[] = {
> MXS_ADC_CHAN(5, IIO_VOLTAGE),
> MXS_ADC_CHAN(6, IIO_VOLTAGE),
> MXS_ADC_CHAN(7, IIO_VOLTAGE), /* VBATT */
> - MXS_ADC_CHAN(8, IIO_TEMP), /* Temp sense 0 */
> - MXS_ADC_CHAN(9, IIO_TEMP), /* Temp sense 1 */
> + /* Combined Temperature sensors */
> + {
> + .type = IIO_TEMP,
> + .indexed = 1,
> + .scan_index = 8,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> + BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_SCALE),
> + .channel = 8,
> + .scan_type = {.sign = 'u', .realbits = 18, .storagebits = 32,},
> + },
> MXS_ADC_CHAN(10, IIO_VOLTAGE), /* VDDIO */
> MXS_ADC_CHAN(11, IIO_VOLTAGE), /* VTH */
> MXS_ADC_CHAN(12, IIO_VOLTAGE), /* VDDA */
>
--
Peter Meerwald
+43-664-2444418 (mobile)
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