linux_kernel/drivers/iio/pressure/ms5611_spi.c

/*
 * MS5611 pressure and temperature sensor driver (SPI bus)
 *
 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
 *
 * 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/module.h>
#include <linux/spi/spi.h>

#include "ms5611.h"

static int ms5611_spi_reset(struct device *dev)
{
	u8 cmd = MS5611_RESET;
	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));

	return spi_write_then_read(st->client, &cmd, 1, NULL, 0);
}

static int ms5611_spi_read_prom_word(struct device *dev, int index, u16 *word)
{
	int ret;
	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));

	ret = spi_w8r16be(st->client, MS5611_READ_PROM_WORD + (index << 1));
	if (ret < 0)
		return ret;

	*word = ret;

	return 0;
}

static int ms5611_spi_read_adc(struct device *dev, s32 *val)
{
	int ret;
	u8 buf[3] = { MS5611_READ_ADC };
	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));

	ret = spi_write_then_read(st->client, buf, 1, buf, 3);
	if (ret < 0)
		return ret;

	*val = (buf[0] << 16) | (buf[1] << 8) | buf[2];

	return 0;
}

static int ms5611_spi_read_adc_temp_and_pressure(struct device *dev,
						 s32 *temp, s32 *pressure)
{
	u8 cmd;
	int ret;
	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));

	cmd = MS5611_START_TEMP_CONV;
	ret = spi_write_then_read(st->client, &cmd, 1, NULL, 0);
	if (ret < 0)
		return ret;

	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);

	ret = ms5611_spi_read_adc(dev, temp);
	if (ret < 0)
		return ret;

	cmd = MS5611_START_PRESSURE_CONV;
	ret = spi_write_then_read(st->client, &cmd, 1, NULL, 0);
	if (ret < 0)
		return ret;

	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);

	return ms5611_spi_read_adc(dev, pressure);
}

static int ms5611_spi_probe(struct spi_device *spi)
{
	int ret;
	struct ms5611_state *st;
	struct iio_dev *indio_dev;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (!indio_dev)
		return -ENOMEM;

	spi->mode = SPI_MODE_0;
	spi->max_speed_hz = 20000000;
	spi->bits_per_word = 8;
	ret = spi_setup(spi);
	if (ret < 0)
		return ret;

	st = iio_priv(indio_dev);
	st->reset = ms5611_spi_reset;
	st->read_prom_word = ms5611_spi_read_prom_word;
	st->read_adc_temp_and_pressure = ms5611_spi_read_adc_temp_and_pressure;
	st->client = spi;

	return ms5611_probe(indio_dev, &spi->dev);
}

static const struct spi_device_id ms5611_id[] = {
	{ "ms5611", 0 },
	{ }
};
MODULE_DEVICE_TABLE(spi, ms5611_id);

static struct spi_driver ms5611_driver = {
	.driver = {
		.name = "ms5611",
		.owner = THIS_MODULE,
	},
	.id_table = ms5611_id,
	.probe = ms5611_spi_probe,
};
module_spi_driver(ms5611_driver);

MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
MODULE_DESCRIPTION("MS5611 spi driver");
MODULE_LICENSE("GPL v2");