ad9850.c

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/*
 * Driver for ADI Direct Digital Synthesis ad9850
 *
 * 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>

#define DRV_NAME "ad9850"

#define value_mask (u16)0xf000
#define addr_shift 12

/* Register format: 4 bits addr + 12 bits value */
struct ad9850_config {
    u8 control[5];
};

struct ad9850_state {
    struct mutex lock;
    struct spi_device *sdev;
};

static ssize_t ad9850_set_parameter(struct device *dev,
                    struct device_attribute *attr,
                    const char *buf,
                    size_t len)
{
    struct spi_message msg;
    struct spi_transfer xfer;
    int ret;
    struct ad9850_config *config = (struct ad9850_config *)buf;
    struct iio_dev *idev = dev_to_iio_dev(dev);
    struct ad9850_state *st = iio_priv(idev);

    xfer.len = len;
    xfer.tx_buf = config;
    mutex_lock(&st->lock);

    spi_message_init(&msg);
    spi_message_add_tail(&xfer, &msg);
    ret = spi_sync(st->sdev, &msg);
    if (ret)
        goto error_ret;
error_ret:
    mutex_unlock(&st->lock);

    return ret ? ret : len;
}

static IIO_DEVICE_ATTR(dds, S_IWUSR, NULL, ad9850_set_parameter, 0);

static struct attribute *ad9850_attributes[] = {
    &iio_dev_attr_dds.dev_attr.attr,
    NULL,
};

static const struct attribute_group ad9850_attribute_group = {
    .attrs = ad9850_attributes,
};

static const struct iio_info ad9850_info = {
    .attrs = &ad9850_attribute_group,
    .driver_module = THIS_MODULE,
};

static int __devinit ad9850_probe(struct spi_device *spi)
{
    struct ad9850_state *st;
    struct iio_dev *idev;
    int ret = 0;

    idev = iio_device_alloc(sizeof(*st));
    if (idev == NULL) {
        ret = -ENOMEM;
        goto error_ret;
    }
    spi_set_drvdata(spi, idev);
    st = iio_priv(idev);
    mutex_init(&st->lock);
    st->sdev = spi;

    idev->dev.parent = &spi->dev;
    idev->info = &ad9850_info;
    idev->modes = INDIO_DIRECT_MODE;

    ret = iio_device_register(idev);
    if (ret)
        goto error_free_dev;
    spi->max_speed_hz = 2000000;
    spi->mode = SPI_MODE_3;
    spi->bits_per_word = 16;
    spi_setup(spi);

    return 0;

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

static int __devexit ad9850_remove(struct spi_device *spi)
{
    iio_device_unregister(spi_get_drvdata(spi));
    iio_device_free(spi_get_drvdata(spi));

    return 0;
}

static struct spi_driver ad9850_driver = {
    .driver = {
        .name = DRV_NAME,
        .owner = THIS_MODULE,
    },
    .probe = ad9850_probe,
    .remove = __devexit_p(ad9850_remove),
};
module_spi_driver(ad9850_driver);

MODULE_AUTHOR("Cliff Cai");
MODULE_DESCRIPTION("Analog Devices ad9850 driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("spi:" DRV_NAME);