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Commit c8231a9a authored by Alexandre Belloni's avatar Alexandre Belloni Committed by Jonathan Cameron
Browse files

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: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 098d3bec

drivers/staging/iio/adc/mxs-lradc.c

+78 −13
Original line number Original line Diff line number Diff line
@@ -759,20 +759,11 @@ static void mxs_lradc_handle_touch(struct mxs_lradc *lradc) 
/*

/*

 * Raw I/O operations

 * Raw I/O operations

 */

 */

static int mxs_lradc_read_raw(struct iio_dev *iio_dev,

static int mxs_lradc_read_single(struct iio_dev *iio_dev, int chan, int *val)

			const struct iio_chan_spec *chan,

			int *val, int *val2, long m)

{

{

	struct mxs_lradc *lradc = iio_priv(iio_dev);

	struct mxs_lradc *lradc = iio_priv(iio_dev);

	int ret;

	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

	 * 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

	 * 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. */

	/* 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_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));

	mxs_lradc_reg_wrt(lradc, 0, LRADC_CH(0));
@@ -824,6 +815,71 @@ static int mxs_lradc_read_raw(struct iio_dev *iio_dev, 
	return ret;

	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 = {

static const struct iio_info mxs_lradc_iio_info = {

	.driver_module		= THIS_MODULE,

	.driver_module		= THIS_MODULE,

	.read_raw		= mxs_lradc_read_raw,

	.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(5, IIO_VOLTAGE),

	MXS_ADC_CHAN(6, IIO_VOLTAGE),

	MXS_ADC_CHAN(6, IIO_VOLTAGE),

	MXS_ADC_CHAN(7, IIO_VOLTAGE),	/* VBATT */

	MXS_ADC_CHAN(7, IIO_VOLTAGE),	/* VBATT */

	MXS_ADC_CHAN(8, IIO_TEMP),	/* Temp sense 0 */

	/* Combined Temperature sensors */

	MXS_ADC_CHAN(9, IIO_TEMP),	/* Temp sense 1 */

	{

		.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(10, IIO_VOLTAGE),	/* VDDIO */

	MXS_ADC_CHAN(11, IIO_VOLTAGE),	/* VTH */

	MXS_ADC_CHAN(11, IIO_VOLTAGE),	/* VTH */

	MXS_ADC_CHAN(12, IIO_VOLTAGE),	/* VDDA */

	MXS_ADC_CHAN(12, IIO_VOLTAGE),	/* VDDA */