From c8231a9af8147f8a401fc55931ec44abfb937660 Mon Sep 17 00:00:00 2001 From: Alexandre Belloni Date: Fri, 6 Dec 2013 19:31:00 +0000 Subject: 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 Signed-off-by: Maxime Ripard Reviewed-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron --- drivers/staging/iio/adc/mxs-lradc.c | 91 +++++++++++++++++++++++++++++++------ 1 file changed, 78 insertions(+), 13 deletions(-) (limited to 'drivers/staging/iio') diff --git a/drivers/staging/iio/adc/mxs-lradc.c b/drivers/staging/iio/adc/mxs-lradc.c index e2dd7830b320..5a4499c3d22a 100644 --- a/drivers/staging/iio/adc/mxs-lradc.c +++ b/drivers/staging/iio/adc/mxs-lradc.c @@ -759,20 +759,11 @@ static void mxs_lradc_handle_touch(struct mxs_lradc *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 @@ -797,7 +788,7 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev, /* Clean the slot's previous content, then set new one. */ mxs_lradc_reg_clear(lradc, LRADC_CTRL4_LRADCSELECT_MASK(0), LRADC_CTRL4); - mxs_lradc_reg_set(lradc, chan->channel, LRADC_CTRL4); + mxs_lradc_reg_set(lradc, chan, LRADC_CTRL4); mxs_lradc_reg_wrt(lradc, 0, LRADC_CH(0)); @@ -824,6 +815,71 @@ 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, @@ -1151,8 +1207,17 @@ 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 */ -- cgit v1.2.1