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 <[email protected]> --- drivers/staging/iio/adc/mxs-lradc.c | 99 ++++++++++++++++++++++++++++++------- 1 file changed, 82 insertions(+), 17 deletions(-) diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c index 163c638..df1d81e 100644 --- a/drivers/staging/iio/adc/mxs-lradc.c +++ b/drivers/staging/iio/adc/mxs-lradc.c @@ -225,26 +225,14 @@ struct mxs_lradc { #define LRADC_CTRL4_LRADCSELECT_MASK(n) (0xf << ((n) * 4)) #define LRADC_CTRL4_LRADCSELECT_OFFSET(n) ((n) * 4) -/* - * 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; unsigned long mask; - if (m != IIO_CHAN_INFO_RAW) - return -EINVAL; - - /* Check for invalid channel */ - if (chan->channel > LRADC_MAX_TOTAL_CHANS) - return -EINVAL; - /* Validate the channel if it doesn't intersect with reserved chans. */ - bitmap_set(&mask, chan->channel, 1); + bitmap_set(&mask, chan, 1); ret = iio_validate_scan_mask_onehot(iio_dev, &mask); if (ret) return -EINVAL; @@ -273,7 +261,7 @@ 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)); @@ -302,6 +290,74 @@ 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; +} + +/* + * 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) +{ + /* 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, @@ -836,8 +892,17 @@ 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 */ -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
