ad2s1200.c

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/*
 * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
 * AD2S1200/1205
 *
 * 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/delay.h>
#include <linux/gpio.h>
#include <linux/module.h>

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

#define DRV_NAME "ad2s1200"

/* input pin sample and rdvel is controlled by driver */
#define AD2S1200_PN 2

/* input clock on serial interface */
#define AD2S1200_HZ 8192000
/* clock period in nano second */
#define AD2S1200_TSCLK  (1000000000/AD2S1200_HZ)

struct ad2s1200_state {
    struct mutex lock;
    struct spi_device *sdev;
    int sample;
    int rdvel;
    u8 rx[2] ____cacheline_aligned;
};

static int ad2s1200_read_raw(struct iio_dev *indio_dev,
               struct iio_chan_spec const *chan,
               int *val,
               int *val2,
               long m)
{
    int ret = 0;
    s16 vel;
    struct ad2s1200_state *st = iio_priv(indio_dev);

    mutex_lock(&st->lock);
    gpio_set_value(st->sample, 0);
    /* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
    udelay(1);
    gpio_set_value(st->sample, 1);
    gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
    ret = spi_read(st->sdev, st->rx, 2);
    if (ret < 0) {
        mutex_unlock(&st->lock);
        return ret;
    }

    switch (chan->type) {
    case IIO_ANGL:
        *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
        break;
    case IIO_ANGL_VEL:
        vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
        vel = (vel << 4) >> 4;
        *val = vel;
    default:
        mutex_unlock(&st->lock);
        return -EINVAL;
    }
    /* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
    udelay(1);
    mutex_unlock(&st->lock);
    return IIO_VAL_INT;
}

static const struct iio_chan_spec ad2s1200_channels[] = {
    {
        .type = IIO_ANGL,
        .indexed = 1,
        .channel = 0,
        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,
    }, {
        .type = IIO_ANGL_VEL,
        .indexed = 1,
        .channel = 0,
        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,
    }
};

static const struct iio_info ad2s1200_info = {
    .read_raw = &ad2s1200_read_raw,
    .driver_module = THIS_MODULE,
};

static int __devinit ad2s1200_probe(struct spi_device *spi)
{
    struct ad2s1200_state *st;
    struct iio_dev *indio_dev;
    int pn, ret = 0;
    unsigned short *pins = spi->dev.platform_data;

    for (pn = 0; pn < AD2S1200_PN; pn++)
        if (gpio_request_one(pins[pn], GPIOF_DIR_OUT, DRV_NAME)) {
            pr_err("%s: request gpio pin %d failed\n",
                        DRV_NAME, pins[pn]);
            goto error_ret;
        }
    indio_dev = iio_device_alloc(sizeof(*st));
    if (indio_dev == NULL) {
        ret = -ENOMEM;
        goto error_ret;
    }
    spi_set_drvdata(spi, indio_dev);
    st = iio_priv(indio_dev);
    mutex_init(&st->lock);
    st->sdev = spi;
    st->sample = pins[0];
    st->rdvel = pins[1];

    indio_dev->dev.parent = &spi->dev;
    indio_dev->info = &ad2s1200_info;
    indio_dev->modes = INDIO_DIRECT_MODE;
    indio_dev->channels = ad2s1200_channels;
    indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
    indio_dev->name = spi_get_device_id(spi)->name;

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

    spi->max_speed_hz = AD2S1200_HZ;
    spi->mode = SPI_MODE_3;
    spi_setup(spi);

    return 0;

error_free_dev:
    iio_device_free(indio_dev);
error_ret:
    for (--pn; pn >= 0; pn--)
        gpio_free(pins[pn]);
    return ret;
}

static int __devexit ad2s1200_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 ad2s1200_id[] = {
    { "ad2s1200" },
    { "ad2s1205" },
    {}
};
MODULE_DEVICE_TABLE(spi, ad2s1200_id);

static struct spi_driver ad2s1200_driver = {
    .driver = {
        .name = DRV_NAME,
        .owner = THIS_MODULE,
    },
    .probe = ad2s1200_probe,
    .remove = __devexit_p(ad2s1200_remove),
    .id_table = ad2s1200_id,
};
module_spi_driver(ad2s1200_driver);

MODULE_AUTHOR("Graff Yang <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
MODULE_LICENSE("GPL v2");