Commit 8cf5f032 authored by Marcus Folkesson's avatar Marcus Folkesson Committed by Jonathan Cameron
Browse files

iio: adc: mcp3911: add support to set PGA 



Add support for setting the Programmable Gain Amplifiers by adjust the
scale value.

Signed-off-by: default avatarMarcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220922194639.1118971-1-marcus.folkesson@gmail.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 4e615140

drivers/iio/adc/mcp3911.c

+80 −24
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ 
#define MCP3911_REG_MOD			0x06

#define MCP3911_REG_PHASE		0x07

#define MCP3911_REG_GAIN		0x09

#define MCP3911_GAIN_MASK(ch)		(GENMASK(2, 0) << 3 * ch)

#define MCP3911_GAIN_VAL(ch, val)      ((val << 3 * ch) & MCP3911_GAIN_MASK(ch))



#define MCP3911_REG_STATUSCOM		0x0a

#define MCP3911_STATUSCOM_DRHIZ         BIT(12)
@@ -60,8 +62,10 @@ 
#define MCP3911_REG_MASK		GENMASK(4, 1)



#define MCP3911_NUM_CHANNELS		2

#define MCP3911_NUM_SCALES		6



static const int mcp3911_osr_table[] = { 32, 64, 128, 256, 512, 1024, 2048, 4096 };

static u32 mcp3911_scale_table[MCP3911_NUM_SCALES][2];



struct mcp3911 {

	struct spi_device *spi;
@@ -70,6 +74,7 @@ struct mcp3911 { 
	struct clk *clki;

	u32 dev_addr;

	struct iio_trigger *trig;

	u32 gain[MCP3911_NUM_CHANNELS];

	struct {

		u32 channels[MCP3911_NUM_CHANNELS];

		s64 ts __aligned(8);
@@ -146,6 +151,11 @@ static int mcp3911_read_avail(struct iio_dev *indio_dev, 
		*vals = mcp3911_osr_table;

		*length = ARRAY_SIZE(mcp3911_osr_table);

		return IIO_AVAIL_LIST;

	case IIO_CHAN_INFO_SCALE:

		*type = IIO_VAL_INT_PLUS_NANO;

		*vals = (int *)mcp3911_scale_table;

		*length = ARRAY_SIZE(mcp3911_scale_table) * 2;

		return IIO_AVAIL_LIST;

	default:

		return -EINVAL;

	}
@@ -190,29 +200,9 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev, 
		break;



	case IIO_CHAN_INFO_SCALE:

		if (adc->vref) {

			ret = regulator_get_voltage(adc->vref);

			if (ret < 0) {

				dev_err(indio_dev->dev.parent,

					"failed to get vref voltage: %d\n",

				       ret);

				goto out;

			}



			*val = ret / 1000;

		} else {

			*val = MCP3911_INT_VREF_MV;

		}



		/*

		 * For 24bit Conversion

		 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5

		 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)

		 */



		/* val2 = (2^23 * 1.5) */

		*val2 = 12582912;

		ret = IIO_VAL_FRACTIONAL;

		*val = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][0];

		*val2 = mcp3911_scale_table[ilog2(adc->gain[channel->channel])][1];

		ret = IIO_VAL_INT_PLUS_NANO;

		break;

	}
@@ -230,6 +220,18 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev, 


	mutex_lock(&adc->lock);

	switch (mask) {

	case IIO_CHAN_INFO_SCALE:

		for (int i = 0; i < MCP3911_NUM_SCALES; i++) {

			if (val == mcp3911_scale_table[i][0] &&

				val2 == mcp3911_scale_table[i][1]) {



				adc->gain[channel->channel] = BIT(i);

				ret = mcp3911_update(adc, MCP3911_REG_GAIN,

						MCP3911_GAIN_MASK(channel->channel),

						MCP3911_GAIN_VAL(channel->channel, i), 1);

			}

		}

		break;

	case IIO_CHAN_INFO_OFFSET:

		if (val2 != 0) {

			ret = -EINVAL;
@@ -265,6 +267,44 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev, 
	return ret;

}



static int mcp3911_calc_scale_table(struct mcp3911 *adc)

{

	u32 ref = MCP3911_INT_VREF_MV;

	u32 div;

	int ret;

	u64 tmp;



	if (adc->vref) {

		ret = regulator_get_voltage(adc->vref);

		if (ret < 0) {

			dev_err(&adc->spi->dev,

				"failed to get vref voltage: %d\n",

			       ret);

			return ret;

		}



		ref = ret / 1000;

	}



	/*

	 * For 24-bit Conversion

	 * Raw = ((Voltage)/(Vref) * 2^23 * Gain * 1.5

	 * Voltage = Raw * (Vref)/(2^23 * Gain * 1.5)

	 *

	 * ref = Reference voltage

	 * div = (2^23 * 1.5 * gain) = 12582912 * gain

	 */

	for (int i = 0; i < MCP3911_NUM_SCALES; i++) {

		div = 12582912 * BIT(i);

		tmp = div_s64((s64)ref * 1000000000LL, div);



		mcp3911_scale_table[i][0] = 0;

		mcp3911_scale_table[i][1] = tmp;

	}



	return 0;

}



#define MCP3911_CHAN(idx) {					\

		.type = IIO_VOLTAGE,				\

		.indexed = 1,					\
@@ -276,6 +316,8 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev, 
			BIT(IIO_CHAN_INFO_SCALE),		\

		.info_mask_shared_by_type_available =           \

			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\

		.info_mask_separate_available =			\

			BIT(IIO_CHAN_INFO_SCALE),		\

		.scan_type = {					\

			.sign = 's',				\

			.realbits = 24,				\
@@ -482,6 +524,20 @@ static int mcp3911_probe(struct spi_device *spi) 
	if (ret)

		return ret;



	ret = mcp3911_calc_scale_table(adc);

	if (ret)

		return ret;



       /* Set gain to 1 for all channels */

	for (int i = 0; i < MCP3911_NUM_CHANNELS; i++) {

		adc->gain[i] = 1;

		ret = mcp3911_update(adc, MCP3911_REG_GAIN,

				MCP3911_GAIN_MASK(i),

				MCP3911_GAIN_VAL(i, 0), 1);

		if (ret)

			return ret;

	}



	indio_dev->name = spi_get_device_id(spi)->name;

	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->info = &mcp3911_info;