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352 lines
8.3 KiB
352 lines
8.3 KiB
// 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 ____cacheline_aligned; |
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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 = 0; |
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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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regulator_disable(st->reg); |
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return ret; |
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} |
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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 <[email protected]>"); |
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MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver"); |
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MODULE_LICENSE("GPL v2");
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