diff options
Diffstat (limited to 'drivers/iio/adc/ad7292.c')
| -rw-r--r-- | drivers/iio/adc/ad7292.c | 352 |
1 files changed, 352 insertions, 0 deletions
diff --git a/drivers/iio/adc/ad7292.c b/drivers/iio/adc/ad7292.c new file mode 100644 index 000000000..3e6ece058 --- /dev/null +++ b/drivers/iio/adc/ad7292.c @@ -0,0 +1,352 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Analog Devices AD7292 SPI ADC driver + * + * Copyright 2019 Analog Devices Inc. + */ + +#include <linux/bitfield.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/regulator/consumer.h> +#include <linux/spi/spi.h> + +#include <linux/iio/iio.h> + +#define ADI_VENDOR_ID 0x0018 + +/* AD7292 registers definition */ +#define AD7292_REG_VENDOR_ID 0x00 +#define AD7292_REG_CONF_BANK 0x05 +#define AD7292_REG_CONV_COMM 0x0E +#define AD7292_REG_ADC_CH(x) (0x10 + (x)) + +/* AD7292 configuration bank subregisters definition */ +#define AD7292_BANK_REG_VIN_RNG0 0x10 +#define AD7292_BANK_REG_VIN_RNG1 0x11 +#define AD7292_BANK_REG_SAMP_MODE 0x12 + +#define AD7292_RD_FLAG_MSK(x) (BIT(7) | ((x) & 0x3F)) + +/* AD7292_REG_ADC_CONVERSION */ +#define AD7292_ADC_DATA_MASK GENMASK(15, 6) +#define AD7292_ADC_DATA(x) FIELD_GET(AD7292_ADC_DATA_MASK, x) + +/* AD7292_CHANNEL_SAMPLING_MODE */ +#define AD7292_CH_SAMP_MODE(reg, ch) (((reg) >> 8) & BIT(ch)) + +/* AD7292_CHANNEL_VIN_RANGE */ +#define AD7292_CH_VIN_RANGE(reg, ch) ((reg) & BIT(ch)) + +#define AD7292_VOLTAGE_CHAN(_chan) \ +{ \ + .type = IIO_VOLTAGE, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ + BIT(IIO_CHAN_INFO_SCALE), \ + .indexed = 1, \ + .channel = _chan, \ +} + +static const struct iio_chan_spec ad7292_channels[] = { + AD7292_VOLTAGE_CHAN(0), + AD7292_VOLTAGE_CHAN(1), + AD7292_VOLTAGE_CHAN(2), + AD7292_VOLTAGE_CHAN(3), + AD7292_VOLTAGE_CHAN(4), + AD7292_VOLTAGE_CHAN(5), + AD7292_VOLTAGE_CHAN(6), + AD7292_VOLTAGE_CHAN(7) +}; + +static const struct iio_chan_spec ad7292_channels_diff[] = { + { + .type = IIO_VOLTAGE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), + .indexed = 1, + .differential = 1, + .channel = 0, + .channel2 = 1, + }, + AD7292_VOLTAGE_CHAN(2), + AD7292_VOLTAGE_CHAN(3), + AD7292_VOLTAGE_CHAN(4), + AD7292_VOLTAGE_CHAN(5), + AD7292_VOLTAGE_CHAN(6), + AD7292_VOLTAGE_CHAN(7) +}; + +struct ad7292_state { + struct spi_device *spi; + struct regulator *reg; + unsigned short vref_mv; + + __be16 d16 ____cacheline_aligned; + u8 d8[2]; +}; + +static int ad7292_spi_reg_read(struct ad7292_state *st, unsigned int addr) +{ + int ret; + + st->d8[0] = AD7292_RD_FLAG_MSK(addr); + + ret = spi_write_then_read(st->spi, st->d8, 1, &st->d16, 2); + if (ret < 0) + return ret; + + return be16_to_cpu(st->d16); +} + +static int ad7292_spi_subreg_read(struct ad7292_state *st, unsigned int addr, + unsigned int sub_addr, unsigned int len) +{ + unsigned int shift = 16 - (8 * len); + int ret; + + st->d8[0] = AD7292_RD_FLAG_MSK(addr); + st->d8[1] = sub_addr; + + ret = spi_write_then_read(st->spi, st->d8, 2, &st->d16, len); + if (ret < 0) + return ret; + + return (be16_to_cpu(st->d16) >> shift); +} + +static int ad7292_single_conversion(struct ad7292_state *st, + unsigned int chan_addr) +{ + int ret; + + struct spi_transfer t[] = { + { + .tx_buf = &st->d8, + .len = 4, + .delay = { + .value = 6, + .unit = SPI_DELAY_UNIT_USECS + }, + }, { + .rx_buf = &st->d16, + .len = 2, + }, + }; + + st->d8[0] = chan_addr; + st->d8[1] = AD7292_RD_FLAG_MSK(AD7292_REG_CONV_COMM); + + ret = spi_sync_transfer(st->spi, t, ARRAY_SIZE(t)); + + if (ret < 0) + return ret; + + return be16_to_cpu(st->d16); +} + +static int ad7292_vin_range_multiplier(struct ad7292_state *st, int channel) +{ + int samp_mode, range0, range1, factor = 1; + + /* + * Every AD7292 ADC channel may have its input range adjusted according + * to the settings at the ADC sampling mode and VIN range subregisters. + * For a given channel, the minimum input range is equal to Vref, and it + * may be increased by a multiplier factor of 2 or 4 according to the + * following rule: + * If channel is being sampled with respect to AGND: + * factor = 4 if VIN range0 and VIN range1 equal 0 + * factor = 2 if only one of VIN ranges equal 1 + * factor = 1 if both VIN range0 and VIN range1 equal 1 + * If channel is being sampled with respect to AVDD: + * factor = 4 if VIN range0 and VIN range1 equal 0 + * Behavior is undefined if any of VIN range doesn't equal 0 + */ + + samp_mode = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK, + AD7292_BANK_REG_SAMP_MODE, 2); + + if (samp_mode < 0) + return samp_mode; + + range0 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK, + AD7292_BANK_REG_VIN_RNG0, 2); + + if (range0 < 0) + return range0; + + range1 = ad7292_spi_subreg_read(st, AD7292_REG_CONF_BANK, + AD7292_BANK_REG_VIN_RNG1, 2); + + if (range1 < 0) + return range1; + + if (AD7292_CH_SAMP_MODE(samp_mode, channel)) { + /* Sampling with respect to AGND */ + if (!AD7292_CH_VIN_RANGE(range0, channel)) + factor *= 2; + + if (!AD7292_CH_VIN_RANGE(range1, channel)) + factor *= 2; + + } else { + /* Sampling with respect to AVDD */ + if (AD7292_CH_VIN_RANGE(range0, channel) || + AD7292_CH_VIN_RANGE(range1, channel)) + return -EPERM; + + factor = 4; + } + + return factor; +} + +static int ad7292_read_raw(struct iio_dev *indio_dev, + const struct iio_chan_spec *chan, + int *val, int *val2, long info) +{ + struct ad7292_state *st = iio_priv(indio_dev); + unsigned int ch_addr; + int ret; + + switch (info) { + case IIO_CHAN_INFO_RAW: + ch_addr = AD7292_REG_ADC_CH(chan->channel); + ret = ad7292_single_conversion(st, ch_addr); + if (ret < 0) + return ret; + + *val = AD7292_ADC_DATA(ret); + + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + /* + * To convert a raw value to standard units, the IIO defines + * this formula: Scaled value = (raw + offset) * scale. + * For the scale to be a correct multiplier for (raw + offset), + * it must be calculated as the input range divided by the + * number of possible distinct input values. Given the ADC data + * is 10 bit long, it may assume 2^10 distinct values. + * Hence, scale = range / 2^10. The IIO_VAL_FRACTIONAL_LOG2 + * return type indicates to the IIO API to divide *val by 2 to + * the power of *val2 when returning from read_raw. + */ + + ret = ad7292_vin_range_multiplier(st, chan->channel); + if (ret < 0) + return ret; + + *val = st->vref_mv * ret; + *val2 = 10; + return IIO_VAL_FRACTIONAL_LOG2; + default: + break; + } + return -EINVAL; +} + +static const struct iio_info ad7292_info = { + .read_raw = ad7292_read_raw, +}; + +static void ad7292_regulator_disable(void *data) +{ + struct ad7292_state *st = data; + + regulator_disable(st->reg); +} + +static int ad7292_probe(struct spi_device *spi) +{ + struct ad7292_state *st; + struct iio_dev *indio_dev; + struct device_node *child; + bool diff_channels = 0; + int ret; + + indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); + if (!indio_dev) + return -ENOMEM; + + st = iio_priv(indio_dev); + st->spi = spi; + + ret = ad7292_spi_reg_read(st, AD7292_REG_VENDOR_ID); + if (ret != ADI_VENDOR_ID) { + dev_err(&spi->dev, "Wrong vendor id 0x%x\n", ret); + return -EINVAL; + } + + spi_set_drvdata(spi, indio_dev); + + st->reg = devm_regulator_get_optional(&spi->dev, "vref"); + if (!IS_ERR(st->reg)) { + ret = regulator_enable(st->reg); + if (ret) { + dev_err(&spi->dev, + "Failed to enable external vref supply\n"); + return ret; + } + + ret = devm_add_action_or_reset(&spi->dev, + ad7292_regulator_disable, st); + if (ret) + return ret; + + ret = regulator_get_voltage(st->reg); + if (ret < 0) + return ret; + + st->vref_mv = ret / 1000; + } else { + /* Use the internal voltage reference. */ + st->vref_mv = 1250; + } + + indio_dev->name = spi_get_device_id(spi)->name; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &ad7292_info; + + for_each_available_child_of_node(spi->dev.of_node, child) { + diff_channels = of_property_read_bool(child, "diff-channels"); + if (diff_channels) { + of_node_put(child); + break; + } + } + + if (diff_channels) { + indio_dev->num_channels = ARRAY_SIZE(ad7292_channels_diff); + indio_dev->channels = ad7292_channels_diff; + } else { + indio_dev->num_channels = ARRAY_SIZE(ad7292_channels); + indio_dev->channels = ad7292_channels; + } + + return devm_iio_device_register(&spi->dev, indio_dev); +} + +static const struct spi_device_id ad7292_id_table[] = { + { "ad7292", 0 }, + {} +}; +MODULE_DEVICE_TABLE(spi, ad7292_id_table); + +static const struct of_device_id ad7292_of_match[] = { + { .compatible = "adi,ad7292" }, + { }, +}; +MODULE_DEVICE_TABLE(of, ad7292_of_match); + +static struct spi_driver ad7292_driver = { + .driver = { + .name = "ad7292", + .of_match_table = ad7292_of_match, + }, + .probe = ad7292_probe, + .id_table = ad7292_id_table, +}; +module_spi_driver(ad7292_driver); + +MODULE_AUTHOR("Marcelo Schmitt <marcelo.schmitt1@gmail.com>"); +MODULE_DESCRIPTION("Analog Devices AD7292 ADC driver"); +MODULE_LICENSE("GPL v2"); |