ad7887_core.c

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/*
 * AD7887 SPI ADC driver
 *
 * Copyright 2010-2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/spi/spi.h>
#include <linux/regulator/consumer.h>
#include <linux/err.h>
#include <linux/module.h>

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


#include "ad7887.h"

static int ad7887_scan_direct(struct ad7887_state *st, unsigned ch)
{
    int ret = spi_sync(st->spi, &st->msg[ch]);
    if (ret)
        return ret;

    return (st->data[(ch * 2)] << 8) | st->data[(ch * 2) + 1];
}

static int ad7887_read_raw(struct iio_dev *indio_dev,
               struct iio_chan_spec const *chan,
               int *val,
               int *val2,
               long m)
{
    int ret;
    struct ad7887_state *st = iio_priv(indio_dev);
    unsigned int scale_uv;

    switch (m) {
    case IIO_CHAN_INFO_RAW:
        mutex_lock(&indio_dev->mlock);
        if (iio_buffer_enabled(indio_dev))
            ret = -EBUSY;
        else
            ret = ad7887_scan_direct(st, chan->address);
        mutex_unlock(&indio_dev->mlock);

        if (ret < 0)
            return ret;
        *val = (ret >> st->chip_info->channel[0].scan_type.shift) &
            RES_MASK(st->chip_info->channel[0].scan_type.realbits);
        return IIO_VAL_INT;
    case IIO_CHAN_INFO_SCALE:
        scale_uv = (st->int_vref_mv * 1000)
            >> st->chip_info->channel[0].scan_type.realbits;
        *val =  scale_uv/1000;
        *val2 = (scale_uv%1000)*1000;
        return IIO_VAL_INT_PLUS_MICRO;
    }
    return -EINVAL;
}


static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
    /*
     * More devices added in future
     */
    [ID_AD7887] = {
        .channel[0] = {
            .type = IIO_VOLTAGE,
            .indexed = 1,
            .channel = 1,
            .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
            IIO_CHAN_INFO_SCALE_SHARED_BIT,
            .address = 1,
            .scan_index = 1,
            .scan_type = IIO_ST('u', 12, 16, 0),
        },
        .channel[1] = {
            .type = IIO_VOLTAGE,
            .indexed = 1,
            .channel = 0,
            .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
            IIO_CHAN_INFO_SCALE_SHARED_BIT,
            .address = 0,
            .scan_index = 0,
            .scan_type = IIO_ST('u', 12, 16, 0),
        },
        .channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
        .int_vref_mv = 2500,
    },
};

static const struct iio_info ad7887_info = {
    .read_raw = &ad7887_read_raw,
    .driver_module = THIS_MODULE,
};

static int __devinit ad7887_probe(struct spi_device *spi)
{
    struct ad7887_platform_data *pdata = spi->dev.platform_data;
    struct ad7887_state *st;
    int ret, voltage_uv = 0;
    struct iio_dev *indio_dev = iio_device_alloc(sizeof(*st));

    if (indio_dev == NULL)
        return -ENOMEM;

    st = iio_priv(indio_dev);

    st->reg = regulator_get(&spi->dev, "vcc");
    if (!IS_ERR(st->reg)) {
        ret = regulator_enable(st->reg);
        if (ret)
            goto error_put_reg;

        voltage_uv = regulator_get_voltage(st->reg);
    }

    st->chip_info =
        &ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];

    spi_set_drvdata(spi, indio_dev);
    st->spi = spi;

    /* Estabilish that the iio_dev is a child of the spi device */
    indio_dev->dev.parent = &spi->dev;
    indio_dev->name = spi_get_device_id(spi)->name;
    indio_dev->info = &ad7887_info;
    indio_dev->modes = INDIO_DIRECT_MODE;

    /* Setup default message */

    st->tx_cmd_buf[0] = AD7887_CH_AIN0 | AD7887_PM_MODE4 |
                ((pdata && pdata->use_onchip_ref) ?
                0 : AD7887_REF_DIS);

    st->xfer[0].rx_buf = &st->data[0];
    st->xfer[0].tx_buf = &st->tx_cmd_buf[0];
    st->xfer[0].len = 2;

    spi_message_init(&st->msg[AD7887_CH0]);
    spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);

    if (pdata && pdata->en_dual) {
        st->tx_cmd_buf[0] |= AD7887_DUAL | AD7887_REF_DIS;

        st->tx_cmd_buf[2] = AD7887_CH_AIN1 | AD7887_DUAL |
                    AD7887_REF_DIS | AD7887_PM_MODE4;
        st->tx_cmd_buf[4] = AD7887_CH_AIN0 | AD7887_DUAL |
                    AD7887_REF_DIS | AD7887_PM_MODE4;
        st->tx_cmd_buf[6] = AD7887_CH_AIN1 | AD7887_DUAL |
                    AD7887_REF_DIS | AD7887_PM_MODE4;

        st->xfer[1].rx_buf = &st->data[0];
        st->xfer[1].tx_buf = &st->tx_cmd_buf[2];
        st->xfer[1].len = 2;

        st->xfer[2].rx_buf = &st->data[2];
        st->xfer[2].tx_buf = &st->tx_cmd_buf[4];
        st->xfer[2].len = 2;

        spi_message_init(&st->msg[AD7887_CH0_CH1]);
        spi_message_add_tail(&st->xfer[1], &st->msg[AD7887_CH0_CH1]);
        spi_message_add_tail(&st->xfer[2], &st->msg[AD7887_CH0_CH1]);

        st->xfer[3].rx_buf = &st->data[0];
        st->xfer[3].tx_buf = &st->tx_cmd_buf[6];
        st->xfer[3].len = 2;

        spi_message_init(&st->msg[AD7887_CH1]);
        spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);

        if (pdata && pdata->vref_mv)
            st->int_vref_mv = pdata->vref_mv;
        else if (voltage_uv)
            st->int_vref_mv = voltage_uv / 1000;
        else
            dev_warn(&spi->dev, "reference voltage unspecified\n");

        indio_dev->channels = st->chip_info->channel;
        indio_dev->num_channels = 3;
    } else {
        if (pdata && pdata->vref_mv)
            st->int_vref_mv = pdata->vref_mv;
        else if (pdata && pdata->use_onchip_ref)
            st->int_vref_mv = st->chip_info->int_vref_mv;
        else
            dev_warn(&spi->dev, "reference voltage unspecified\n");

        indio_dev->channels = &st->chip_info->channel[1];
        indio_dev->num_channels = 2;
    }

    ret = ad7887_register_ring_funcs_and_init(indio_dev);
    if (ret)
        goto error_disable_reg;

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

    return 0;
error_unregister_ring:
    ad7887_ring_cleanup(indio_dev);
error_disable_reg:
    if (!IS_ERR(st->reg))
        regulator_disable(st->reg);
error_put_reg:
    if (!IS_ERR(st->reg))
        regulator_put(st->reg);
    iio_device_free(indio_dev);

    return ret;
}

static int __devexit ad7887_remove(struct spi_device *spi)
{
    struct iio_dev *indio_dev = spi_get_drvdata(spi);
    struct ad7887_state *st = iio_priv(indio_dev);

    iio_device_unregister(indio_dev);
    ad7887_ring_cleanup(indio_dev);
    if (!IS_ERR(st->reg)) {
        regulator_disable(st->reg);
        regulator_put(st->reg);
    }
    iio_device_free(indio_dev);

    return 0;
}

static const struct spi_device_id ad7887_id[] = {
    {"ad7887", ID_AD7887},
    {}
};
MODULE_DEVICE_TABLE(spi, ad7887_id);

static struct spi_driver ad7887_driver = {
    .driver = {
        .name   = "ad7887",
        .owner  = THIS_MODULE,
    },
    .probe      = ad7887_probe,
    .remove     = __devexit_p(ad7887_remove),
    .id_table   = ad7887_id,
};
module_spi_driver(ad7887_driver);

MODULE_AUTHOR("Michael Hennerich <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD7887 ADC");
MODULE_LICENSE("GPL v2");