forked from Minki/linux
iio: mxs-lradc: compute temperature from channel 8 and 9
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. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Reviewed-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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@ -759,20 +759,11 @@ static void mxs_lradc_handle_touch(struct mxs_lradc *lradc)
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/*
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* Raw I/O operations
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*/
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static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
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const struct iio_chan_spec *chan,
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int *val, int *val2, long m)
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static int mxs_lradc_read_single(struct iio_dev *iio_dev, int chan, int *val)
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{
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struct mxs_lradc *lradc = iio_priv(iio_dev);
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int ret;
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if (m != IIO_CHAN_INFO_RAW)
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return -EINVAL;
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/* Check for invalid channel */
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if (chan->channel > LRADC_MAX_TOTAL_CHANS)
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return -EINVAL;
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/*
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* See if there is no buffered operation in progess. If there is, simply
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* bail out. This can be improved to support both buffered and raw IO at
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@ -797,7 +788,7 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
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/* Clean the slot's previous content, then set new one. */
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mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(0), LRADC_CTRL4);
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mxs_lradc_reg_set(lradc, chan->channel, LRADC_CTRL4);
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mxs_lradc_reg_set(lradc, chan, LRADC_CTRL4);
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mxs_lradc_reg_wrt(lradc, 0, LRADC_CH(0));
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@ -824,6 +815,71 @@ err:
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return ret;
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}
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static int mxs_lradc_read_temp(struct iio_dev *iio_dev, int *val)
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{
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int ret, min, max;
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ret = mxs_lradc_read_single(iio_dev, 8, &min);
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if (ret != IIO_VAL_INT)
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return ret;
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ret = mxs_lradc_read_single(iio_dev, 9, &max);
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if (ret != IIO_VAL_INT)
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return ret;
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*val = max - min;
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return IIO_VAL_INT;
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}
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static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
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const struct iio_chan_spec *chan,
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int *val, int *val2, long m)
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{
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/* Check for invalid channel */
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if (chan->channel > LRADC_MAX_TOTAL_CHANS)
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return -EINVAL;
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switch (m) {
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case IIO_CHAN_INFO_RAW:
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if (chan->type == IIO_TEMP)
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return mxs_lradc_read_temp(iio_dev, val);
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return mxs_lradc_read_single(iio_dev, chan->channel, val);
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case IIO_CHAN_INFO_SCALE:
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if (chan->type == IIO_TEMP) {
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/* From the datasheet, we have to multiply by 1.012 and
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* divide by 4
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*/
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*val = 0;
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*val2 = 253000;
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return IIO_VAL_INT_PLUS_MICRO;
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}
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return -EINVAL;
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case IIO_CHAN_INFO_OFFSET:
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if (chan->type == IIO_TEMP) {
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/* The calculated value from the ADC is in Kelvin, we
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* want Celsius for hwmon so the offset is
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* -272.15 * scale
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*/
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*val = -1075;
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*val2 = 691699;
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return IIO_VAL_INT_PLUS_MICRO;
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}
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return -EINVAL;
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default:
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break;
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}
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return -EINVAL;
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}
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static const struct iio_info mxs_lradc_iio_info = {
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.driver_module = THIS_MODULE,
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.read_raw = mxs_lradc_read_raw,
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@ -1151,8 +1207,17 @@ static const struct iio_chan_spec mxs_lradc_chan_spec[] = {
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MXS_ADC_CHAN(5, IIO_VOLTAGE),
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MXS_ADC_CHAN(6, IIO_VOLTAGE),
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MXS_ADC_CHAN(7, IIO_VOLTAGE), /* VBATT */
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MXS_ADC_CHAN(8, IIO_TEMP), /* Temp sense 0 */
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MXS_ADC_CHAN(9, IIO_TEMP), /* Temp sense 1 */
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/* Combined Temperature sensors */
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{
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.type = IIO_TEMP,
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.indexed = 1,
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.scan_index = 8,
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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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.channel = 8,
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.scan_type = {.sign = 'u', .realbits = 18, .storagebits = 32,},
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},
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MXS_ADC_CHAN(10, IIO_VOLTAGE), /* VDDIO */
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MXS_ADC_CHAN(11, IIO_VOLTAGE), /* VTH */
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MXS_ADC_CHAN(12, IIO_VOLTAGE), /* VDDA */
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