351 lines
8.3 KiB
C
351 lines
8.3 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Analog Devices AD7292 SPI ADC driver
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*
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* Copyright 2019 Analog Devices Inc.
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*/
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#include <linux/bitfield.h>
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/regulator/consumer.h>
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#include <linux/spi/spi.h>
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#include <linux/iio/iio.h>
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#define ADI_VENDOR_ID 0x0018
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/* AD7292 registers definition */
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#define AD7292_REG_VENDOR_ID 0x00
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#define AD7292_REG_CONF_BANK 0x05
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#define AD7292_REG_CONV_COMM 0x0E
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#define AD7292_REG_ADC_CH(x) (0x10 + (x))
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/* AD7292 configuration bank subregisters definition */
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#define AD7292_BANK_REG_VIN_RNG0 0x10
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#define AD7292_BANK_REG_VIN_RNG1 0x11
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#define AD7292_BANK_REG_SAMP_MODE 0x12
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#define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F))
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/* AD7292_REG_ADC_CONVERSION */
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#define AD7292_ADC_DATA_MASK GENMASK(15, 6)
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#define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x)
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/* AD7292_CHANNEL_SAMPLING_MODE */
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#define AD7292_CH_SAMP_MODE(reg, ch) (((reg) >> 8) & BIT(ch))
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/* AD7292_CHANNEL_VIN_RANGE */
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#define AD7292_CH_VIN_RANGE(reg, ch) ((reg) & BIT(ch))
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#define AD7292_VOLTAGE_CHAN(_chan) \
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{ \
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.type = IIO_VOLTAGE, \
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
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BIT(IIO_CHAN_INFO_SCALE), \
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.indexed = 1, \
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.channel = _chan, \
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}
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static const struct iio_chan_spec ad7292_channels[] = {
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AD7292_VOLTAGE_CHAN(0),
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AD7292_VOLTAGE_CHAN(1),
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AD7292_VOLTAGE_CHAN(2),
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AD7292_VOLTAGE_CHAN(3),
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AD7292_VOLTAGE_CHAN(4),
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AD7292_VOLTAGE_CHAN(5),
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AD7292_VOLTAGE_CHAN(6),
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AD7292_VOLTAGE_CHAN(7)
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};
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static const struct iio_chan_spec ad7292_channels_diff[] = {
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{
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
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.indexed = 1,
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.differential = 1,
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.channel = 0,
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.channel2 = 1,
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},
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AD7292_VOLTAGE_CHAN(2),
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AD7292_VOLTAGE_CHAN(3),
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AD7292_VOLTAGE_CHAN(4),
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AD7292_VOLTAGE_CHAN(5),
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AD7292_VOLTAGE_CHAN(6),
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AD7292_VOLTAGE_CHAN(7)
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};
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struct ad7292_state {
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struct spi_device *spi;
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struct regulator *reg;
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unsigned short vref_mv;
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__be16 d16 __aligned(IIO_DMA_MINALIGN);
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u8 d8[2];
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};
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static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr)
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{
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int ret;
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st->d8[0] = AD7292_RD_FLAG_MSK(addr);
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ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2);
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if (ret < 0)
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return ret;
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return be16_to_cpu(st->d16);
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}
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static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr,
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unsigned int sub_addr, unsigned int len)
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{
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unsigned int shift = 16 - (8 * len);
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int ret;
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st->d8[0] = AD7292_RD_FLAG_MSK(addr);
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st->d8[1] = sub_addr;
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ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len);
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if (ret < 0)
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return ret;
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return (be16_to_cpu(st->d16) >> shift);
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}
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static int ad7292_single_conversion(struct ad7292_state *st,
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unsigned int chan_addr)
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{
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int ret;
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struct spi_transfer t[] = {
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{
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.tx_buf = &st->d8,
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.len = 4,
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.delay = {
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.value = 6,
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.unit = SPI_DELAY_UNIT_USECS
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},
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}, {
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.rx_buf = &st->d16,
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.len = 2,
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},
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};
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st->d8[0] = chan_addr;
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st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM);
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ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t));
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if (ret < 0)
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return ret;
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return be16_to_cpu(st->d16);
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}
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static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel)
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{
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int samp_mode, range0, range1, factor = 1;
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/*
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* Every AD7292 ADC channel may have its input range adjusted according
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* to the settings at the ADC sampling mode and VIN range subregisters.
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* For a given channel, the minimum input range is equal to Vref, and it
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* may be increased by a multiplier factor of 2 or 4 according to the
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* following rule:
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* If channel is being sampled with respect to AGND:
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* factor = 4 if VIN range0 and VIN range1 equal 0
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* factor = 2 if only one of VIN ranges equal 1
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* factor = 1 if both VIN range0 and VIN range1 equal 1
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* If channel is being sampled with respect to AVDD:
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* factor = 4 if VIN range0 and VIN range1 equal 0
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* Behavior is undefined if any of VIN range doesn't equal 0
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*/
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samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
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AD7292_BANK_REG_SAMP_MODE, 2);
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if (samp_mode < 0)
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return samp_mode;
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range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
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AD7292_BANK_REG_VIN_RNG0, 2);
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if (range0 < 0)
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return range0;
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range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK,
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AD7292_BANK_REG_VIN_RNG1, 2);
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if (range1 < 0)
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return range1;
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if (AD7292_CH_SAMP_MODE(samp_mode, channel)) {
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/* Sampling with respect to AGND */
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if (!AD7292_CH_VIN_RANGE(range0, channel))
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factor *= 2;
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if (!AD7292_CH_VIN_RANGE(range1, channel))
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factor *= 2;
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} else {
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/* Sampling with respect to AVDD */
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if (AD7292_CH_VIN_RANGE(range0, channel) ||
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AD7292_CH_VIN_RANGE(range1, channel))
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return -EPERM;
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factor = 4;
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}
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return factor;
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}
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static int ad7292_read_raw(struct iio_dev *indio_dev,
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const struct iio_chan_spec *chan,
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int *val, int *val2, long info)
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{
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struct ad7292_state *st = iio_priv(indio_dev);
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unsigned int ch_addr;
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int ret;
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switch (info) {
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case IIO_CHAN_INFO_RAW:
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ch_addr = AD7292_REG_ADC_CH(chan->channel);
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ret = ad7292_single_conversion(st, ch_addr);
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if (ret < 0)
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return ret;
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*val = AD7292_ADC_DATA(ret);
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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/*
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* To convert a raw value to standard units, the IIO defines
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* this formula: Scaled value = (raw + offset) * scale.
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* For the scale to be a correct multiplier for (raw + offset),
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* it must be calculated as the input range divided by the
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* number of possible distinct input values. Given the ADC data
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* is 10 bit long, it may assume 2^10 distinct values.
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* Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2
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* return type indicates to the IIO API to divide *val by 2 to
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* the power of *val2 when returning from read_raw.
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*/
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ret = ad7292_vin_range_multiplier(st, chan->channel);
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if (ret < 0)
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return ret;
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*val = st->vref_mv * ret;
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*val2 = 10;
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return IIO_VAL_FRACTIONAL_LOG2;
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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 ad7292_info = {
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.read_raw = ad7292_read_raw,
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};
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static void ad7292_regulator_disable(void *data)
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{
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struct ad7292_state *st = data;
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regulator_disable(st->reg);
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}
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static int ad7292_probe(struct spi_device *spi)
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{
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struct ad7292_state *st;
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struct iio_dev *indio_dev;
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struct device_node *child;
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bool diff_channels = false;
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int ret;
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
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if (!indio_dev)
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return -ENOMEM;
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st = iio_priv(indio_dev);
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st->spi = spi;
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ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID);
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if (ret != ADI_VENDOR_ID) {
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dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret);
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return -EINVAL;
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}
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st->reg = devm_regulator_get_optional(&spi->dev, "vref");
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if (!IS_ERR(st->reg)) {
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ret = regulator_enable(st->reg);
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if (ret) {
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dev_err(&spi->dev,
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"Failed to enable external vref supply\n");
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return ret;
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}
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ret = devm_add_action_or_reset(&spi->dev,
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ad7292_regulator_disable, st);
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if (ret)
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return ret;
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ret = regulator_get_voltage(st->reg);
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if (ret < 0)
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return ret;
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st->vref_mv = ret / 1000;
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} else {
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/* Use the internal voltage reference. */
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st->vref_mv = 1250;
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}
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indio_dev->name = spi_get_device_id(spi)->name;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->info = &ad7292_info;
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for_each_available_child_of_node(spi->dev.of_node, child) {
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diff_channels = of_property_read_bool(child, "diff-channels");
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if (diff_channels) {
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of_node_put(child);
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break;
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}
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}
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if (diff_channels) {
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indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff);
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indio_dev->channels = ad7292_channels_diff;
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} else {
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indio_dev->num_channels = ARRAY_SIZE(ad7292_channels);
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indio_dev->channels = ad7292_channels;
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}
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return devm_iio_device_register(&spi->dev, indio_dev);
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}
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static const struct spi_device_id ad7292_id_table[] = {
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{ "ad7292", 0 },
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{}
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};
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MODULE_DEVICE_TABLE(spi, ad7292_id_table);
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static const struct of_device_id ad7292_of_match[] = {
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{ .compatible = "adi,ad7292" },
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{ },
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};
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MODULE_DEVICE_TABLE(of, ad7292_of_match);
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static struct spi_driver ad7292_driver = {
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.driver = {
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.name = "ad7292",
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.of_match_table = ad7292_of_match,
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},
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.probe = ad7292_probe,
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.id_table = ad7292_id_table,
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};
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module_spi_driver(ad7292_driver);
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MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@gmail.com>");
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MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver");
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MODULE_LICENSE("GPL v2");
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