180 lines
4 KiB
C
180 lines
4 KiB
C
/*
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* iio/adc/max11100.c
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* Maxim max11100 ADC Driver with IIO interface
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*
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* Copyright (C) 2016-17 Renesas Electronics Corporation
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* Copyright (C) 2016-17 Jacopo Mondi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/delay.h>
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#include <linux/kernel.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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#include <linux/iio/driver.h>
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/*
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* LSB is the ADC single digital step
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* 1 LSB = (vref_mv / 2 ^ 16)
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*
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* LSB is used to calculate analog voltage value
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* from the number of ADC steps count
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*
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* Ain = (count * LSB)
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*/
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#define MAX11100_LSB_DIV (1 << 16)
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struct max11100_state {
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struct regulator *vref_reg;
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struct spi_device *spi;
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/*
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* DMA (thus cache coherency maintenance) requires the
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* transfer buffers to live in their own cache lines.
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*/
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u8 buffer[3] ____cacheline_aligned;
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};
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static struct iio_chan_spec max11100_channels[] = {
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{ /* [0] */
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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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},
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};
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static int max11100_read_single(struct iio_dev *indio_dev, int *val)
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{
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int ret;
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struct max11100_state *state = iio_priv(indio_dev);
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ret = spi_read(state->spi, state->buffer, sizeof(state->buffer));
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if (ret) {
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dev_err(&indio_dev->dev, "SPI transfer failed\n");
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return ret;
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}
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/* the first 8 bits sent out from ADC must be 0s */
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if (state->buffer[0]) {
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dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
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return -EINVAL;
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}
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*val = (state->buffer[1] << 8) | state->buffer[2];
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return 0;
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}
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static int max11100_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long info)
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{
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int ret, vref_uv;
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struct max11100_state *state = iio_priv(indio_dev);
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switch (info) {
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case IIO_CHAN_INFO_RAW:
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ret = max11100_read_single(indio_dev, val);
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if (ret)
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return ret;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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vref_uv = regulator_get_voltage(state->vref_reg);
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if (vref_uv < 0)
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/* dummy regulator "get_voltage" returns -EINVAL */
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return -EINVAL;
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*val = vref_uv / 1000;
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*val2 = MAX11100_LSB_DIV;
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return IIO_VAL_FRACTIONAL;
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}
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return -EINVAL;
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}
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static const struct iio_info max11100_info = {
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.read_raw = max11100_read_raw,
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};
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static int max11100_probe(struct spi_device *spi)
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{
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int ret;
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struct iio_dev *indio_dev;
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struct max11100_state *state;
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
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if (!indio_dev)
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return -ENOMEM;
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spi_set_drvdata(spi, indio_dev);
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state = iio_priv(indio_dev);
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state->spi = spi;
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indio_dev->dev.parent = &spi->dev;
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indio_dev->dev.of_node = spi->dev.of_node;
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indio_dev->name = "max11100";
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indio_dev->info = &max11100_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = max11100_channels;
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indio_dev->num_channels = ARRAY_SIZE(max11100_channels);
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state->vref_reg = devm_regulator_get(&spi->dev, "vref");
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if (IS_ERR(state->vref_reg))
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return PTR_ERR(state->vref_reg);
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ret = regulator_enable(state->vref_reg);
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if (ret)
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return ret;
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ret = iio_device_register(indio_dev);
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if (ret)
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goto disable_regulator;
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return 0;
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disable_regulator:
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regulator_disable(state->vref_reg);
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return ret;
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}
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static int max11100_remove(struct spi_device *spi)
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{
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struct iio_dev *indio_dev = spi_get_drvdata(spi);
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struct max11100_state *state = iio_priv(indio_dev);
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iio_device_unregister(indio_dev);
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regulator_disable(state->vref_reg);
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return 0;
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}
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static const struct of_device_id max11100_ids[] = {
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{.compatible = "maxim,max11100"},
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{ },
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};
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MODULE_DEVICE_TABLE(of, max11100_ids);
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static struct spi_driver max11100_driver = {
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.driver = {
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.name = "max11100",
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.of_match_table = of_match_ptr(max11100_ids),
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},
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.probe = max11100_probe,
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.remove = max11100_remove,
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};
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module_spi_driver(max11100_driver);
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MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
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MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
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MODULE_LICENSE("GPL v2");
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