linux/drivers/iio/dac/dpot-dac.c

// SPDX-License-Identifier: GPL-2.0
/*
 * IIO DAC emulation driver using a digital potentiometer
 *
 * Copyright (C) 2016 Axentia Technologies AB
 *
 * Author: Peter Rosin <[email protected]>
 */

/*
 * It is assumed that the dpot is used as a voltage divider between the
 * current dpot wiper setting and the maximum resistance of the dpot. The
 * divided voltage is provided by a vref regulator.
 *
 *                   .------.
 *    .-----------.  |      |
 *    | vref      |--'    .---.
 *    | regulator |--.    |   |
 *    '-----------'  |    | d |
 *                   |    | p |
 *                   |    | o |  wiper
 *                   |    | t |<---------+
 *                   |    |   |
 *                   |    '---'       dac output voltage
 *                   |      |
 *                   '------+------------+
 */

#include <linux/err.h>
#include <linux/iio/consumer.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>

struct dpot_dac { … };

static const struct iio_chan_spec dpot_dac_iio_channel = …;

static int dpot_dac_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int *val, int *val2, long mask)
{ … }

static int dpot_dac_read_avail(struct iio_dev *indio_dev,
			       struct iio_chan_spec const *chan,
			       const int **vals, int *type, int *length,
			       long mask)
{ … }

static int dpot_dac_write_raw(struct iio_dev *indio_dev,
			      struct iio_chan_spec const *chan,
			      int val, int val2, long mask)
{ … }

static const struct iio_info dpot_dac_info = …;

static int dpot_dac_channel_max_ohms(struct iio_dev *indio_dev)
{ … }

static int dpot_dac_probe(struct platform_device *pdev)
{ … }

static void dpot_dac_remove(struct platform_device *pdev)
{ … }

static const struct of_device_id dpot_dac_match[] = …;
MODULE_DEVICE_TABLE(of, dpot_dac_match);

static struct platform_driver dpot_dac_driver = …;
module_platform_driver(…) …;

MODULE_DESCRIPTION(…) …;
MODULE_AUTHOR(…) …;
MODULE_LICENSE(…) …;