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