ad7298_core.c

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/*
 * AD7298 SPI ADC driver
 *
 * Copyright 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/delay.h>
#include <linux/module.h>

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

#include "ad7298.h"

#define AD7298_V_CHAN(index)                        \
    {                               \
        .type = IIO_VOLTAGE,                    \
        .indexed = 1,                       \
        .channel = index,                   \
        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |       \
        IIO_CHAN_INFO_SCALE_SHARED_BIT,             \
        .address = index,                   \
        .scan_index = index,                    \
        .scan_type = {                      \
            .sign = 'u',                    \
            .realbits = 12,                 \
            .storagebits = 16,              \
        },                          \
    }

static const struct iio_chan_spec ad7298_channels[] = {
    {
        .type = IIO_TEMP,
        .indexed = 1,
        .channel = 0,
        .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
        IIO_CHAN_INFO_SCALE_SEPARATE_BIT,
        .address = AD7298_CH_TEMP,
        .scan_index = -1,
        .scan_type = {
            .sign = 's',
            .realbits = 32,
            .storagebits = 32,
        },
    },
    AD7298_V_CHAN(0),
    AD7298_V_CHAN(1),
    AD7298_V_CHAN(2),
    AD7298_V_CHAN(3),
    AD7298_V_CHAN(4),
    AD7298_V_CHAN(5),
    AD7298_V_CHAN(6),
    AD7298_V_CHAN(7),
    IIO_CHAN_SOFT_TIMESTAMP(8),
};

static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
{
    int ret;
    st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
                   (AD7298_CH(0) >> ch));

    ret = spi_sync(st->spi, &st->scan_single_msg);
    if (ret)
        return ret;

    return be16_to_cpu(st->rx_buf[0]);
}

static int ad7298_scan_temp(struct ad7298_state *st, int *val)
{
    int tmp, ret;
    __be16 buf;

    buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
              AD7298_TAVG | st->ext_ref);

    ret = spi_write(st->spi, (u8 *)&buf, 2);
    if (ret)
        return ret;

    buf = cpu_to_be16(0);

    ret = spi_write(st->spi, (u8 *)&buf, 2);
    if (ret)
        return ret;

    usleep_range(101, 1000); /* sleep > 100us */

    ret = spi_read(st->spi, (u8 *)&buf, 2);
    if (ret)
        return ret;

    tmp = be16_to_cpu(buf) & RES_MASK(AD7298_BITS);

    /*
     * One LSB of the ADC corresponds to 0.25 deg C.
     * The temperature reading is in 12-bit twos complement format
     */

    if (tmp & (1 << (AD7298_BITS - 1))) {
        tmp = (4096 - tmp) * 250;
        tmp -= (2 * tmp);

    } else {
        tmp *= 250; /* temperature in milli degrees Celsius */
    }

    *val = tmp;

    return 0;
}

static int ad7298_read_raw(struct iio_dev *indio_dev,
               struct iio_chan_spec const *chan,
               int *val,
               int *val2,
               long m)
{
    int ret;
    struct ad7298_state *st = iio_priv(indio_dev);
    unsigned int scale_uv;

    switch (m) {
    case IIO_CHAN_INFO_RAW:
        mutex_lock(&indio_dev->mlock);
        if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
            ret = -EBUSY;
        } else {
            if (chan->address == AD7298_CH_TEMP)
                ret = ad7298_scan_temp(st, val);
            else
                ret = ad7298_scan_direct(st, chan->address);
        }
        mutex_unlock(&indio_dev->mlock);

        if (ret < 0)
            return ret;

        if (chan->address != AD7298_CH_TEMP)
            *val = ret & RES_MASK(AD7298_BITS);

        return IIO_VAL_INT;
    case IIO_CHAN_INFO_SCALE:
        switch (chan->type) {
        case IIO_VOLTAGE:
            scale_uv = (st->int_vref_mv * 1000) >> AD7298_BITS;
            *val =  scale_uv / 1000;
            *val2 = (scale_uv % 1000) * 1000;
            return IIO_VAL_INT_PLUS_MICRO;
        case IIO_TEMP:
            *val =  1;
            *val2 = 0;
            return IIO_VAL_INT_PLUS_MICRO;
        default:
            return -EINVAL;
        }
    }
    return -EINVAL;
}

static const struct iio_info ad7298_info = {
    .read_raw = &ad7298_read_raw,
    .update_scan_mode = ad7298_update_scan_mode,
    .driver_module = THIS_MODULE,
};

static int __devinit ad7298_probe(struct spi_device *spi)
{
    struct ad7298_platform_data *pdata = spi->dev.platform_data;
    struct ad7298_state *st;
    int ret;
    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;
    }

    spi_set_drvdata(spi, indio_dev);

    st->spi = spi;

    indio_dev->name = spi_get_device_id(spi)->name;
    indio_dev->dev.parent = &spi->dev;
    indio_dev->modes = INDIO_DIRECT_MODE;
    indio_dev->channels = ad7298_channels;
    indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
    indio_dev->info = &ad7298_info;

    /* Setup default message */

    st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
    st->scan_single_xfer[0].len = 2;
    st->scan_single_xfer[0].cs_change = 1;
    st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
    st->scan_single_xfer[1].len = 2;
    st->scan_single_xfer[1].cs_change = 1;
    st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
    st->scan_single_xfer[2].len = 2;

    spi_message_init(&st->scan_single_msg);
    spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
    spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
    spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);

    if (pdata && pdata->vref_mv) {
        st->int_vref_mv = pdata->vref_mv;
        st->ext_ref = AD7298_EXTREF;
    } else {
        st->int_vref_mv = AD7298_INTREF_mV;
    }

    ret = ad7298_register_ring_funcs_and_init(indio_dev);
    if (ret)
        goto error_disable_reg;

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

    return 0;

error_cleanup_ring:
    ad7298_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 ad7298_remove(struct spi_device *spi)
{
    struct iio_dev *indio_dev = spi_get_drvdata(spi);
    struct ad7298_state *st = iio_priv(indio_dev);

    iio_device_unregister(indio_dev);
    ad7298_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 ad7298_id[] = {
    {"ad7298", 0},
    {}
};
MODULE_DEVICE_TABLE(spi, ad7298_id);

static struct spi_driver ad7298_driver = {
    .driver = {
        .name   = "ad7298",
        .owner  = THIS_MODULE,
    },
    .probe      = ad7298_probe,
    .remove     = __devexit_p(ad7298_remove),
    .id_table   = ad7298_id,
};
module_spi_driver(ad7298_driver);

MODULE_AUTHOR("Michael Hennerich <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
MODULE_LICENSE("GPL v2");