ad2s90.c

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/*
 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
 *
 * Copyright (c) 2010-2010 Analog Devices Inc.
 *
 * 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/types.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/module.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

struct ad2s90_state {
    struct mutex lock;
    struct spi_device *sdev;
    u8 rx[2] ____cacheline_aligned;
};

static int ad2s90_read_raw(struct iio_dev *indio_dev,
               struct iio_chan_spec const *chan,
               int *val,
               int *val2,
               long m)
{
    int ret;
    struct ad2s90_state *st = iio_priv(indio_dev);

    mutex_lock(&st->lock);
    ret = spi_read(st->sdev, st->rx, 2);
    if (ret)
        goto error_ret;
    *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);

error_ret:
    mutex_unlock(&st->lock);

    return IIO_VAL_INT;
}

static const struct iio_info ad2s90_info = {
    .read_raw = &ad2s90_read_raw,
    .driver_module = THIS_MODULE,
};

static const struct iio_chan_spec ad2s90_chan = {
    .type = IIO_ANGL,
    .indexed = 1,
    .channel = 0,
    .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,
};

static int __devinit ad2s90_probe(struct spi_device *spi)
{
    struct iio_dev *indio_dev;
    struct ad2s90_state *st;
    int ret = 0;

    indio_dev = iio_device_alloc(sizeof(*st));
    if (indio_dev == NULL) {
        ret = -ENOMEM;
        goto error_ret;
    }
    st = iio_priv(indio_dev);
    spi_set_drvdata(spi, indio_dev);

    mutex_init(&st->lock);
    st->sdev = spi;
    indio_dev->dev.parent = &spi->dev;
    indio_dev->info = &ad2s90_info;
    indio_dev->modes = INDIO_DIRECT_MODE;
    indio_dev->channels = &ad2s90_chan;
    indio_dev->num_channels = 1;
    indio_dev->name = spi_get_device_id(spi)->name;

    ret = iio_device_register(indio_dev);
    if (ret)
        goto error_free_dev;

    /* need 600ns between CS and the first falling edge of SCLK */
    spi->max_speed_hz = 830000;
    spi->mode = SPI_MODE_3;
    spi_setup(spi);

    return 0;

error_free_dev:
    iio_device_free(indio_dev);
error_ret:
    return ret;
}

static int __devexit ad2s90_remove(struct spi_device *spi)
{
    iio_device_unregister(spi_get_drvdata(spi));
    iio_device_free(spi_get_drvdata(spi));

    return 0;
}

static const struct spi_device_id ad2s90_id[] = {
    { "ad2s90" },
    {}
};
MODULE_DEVICE_TABLE(spi, ad2s90_id);

static struct spi_driver ad2s90_driver = {
    .driver = {
        .name = "ad2s90",
        .owner = THIS_MODULE,
    },
    .probe = ad2s90_probe,
    .remove = __devexit_p(ad2s90_remove),
    .id_table = ad2s90_id,
};
module_spi_driver(ad2s90_driver);

MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
MODULE_LICENSE("GPL v2");