ad7780.c

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/*
 * AD7170/AD7171 and AD7780/AD7781 SPI ADC driver
 *
 * Copyright 2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2.
 */

#include <linux/interrupt.h>
#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/sched.h>
#include <linux/gpio.h>
#include <linux/module.h>

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

#include "ad7780.h"

#define AD7780_RDY  (1 << 7)
#define AD7780_FILTER   (1 << 6)
#define AD7780_ERR  (1 << 5)
#define AD7780_ID1  (1 << 4)
#define AD7780_ID0  (1 << 3)
#define AD7780_GAIN (1 << 2)
#define AD7780_PAT1 (1 << 1)
#define AD7780_PAT0 (1 << 0)

struct ad7780_chip_info {
    struct iio_chan_spec    channel;
    unsigned int        pattern_mask;
    unsigned int        pattern;
};

struct ad7780_state {
    const struct ad7780_chip_info   *chip_info;
    struct regulator        *reg;
    int             powerdown_gpio;
    unsigned int    gain;
    u16             int_vref_mv;

    struct ad_sigma_delta sd;
};

enum ad7780_supported_device_ids {
    ID_AD7170,
    ID_AD7171,
    ID_AD7780,
    ID_AD7781,
};

static struct ad7780_state *ad_sigma_delta_to_ad7780(struct ad_sigma_delta *sd)
{
    return container_of(sd, struct ad7780_state, sd);
}

static int ad7780_set_mode(struct ad_sigma_delta *sigma_delta,
    enum ad_sigma_delta_mode mode)
{
    struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
    unsigned val;

    switch (mode) {
    case AD_SD_MODE_SINGLE:
    case AD_SD_MODE_CONTINUOUS:
        val = 1;
        break;
    default:
        val = 0;
        break;
    }

    if (gpio_is_valid(st->powerdown_gpio))
        gpio_set_value(st->powerdown_gpio, val);

    return 0;
}

static int ad7780_read_raw(struct iio_dev *indio_dev,
               struct iio_chan_spec const *chan,
               int *val,
               int *val2,
               long m)
{
    struct ad7780_state *st = iio_priv(indio_dev);
    unsigned long scale_uv;

    switch (m) {
    case IIO_CHAN_INFO_RAW:
        return ad_sigma_delta_single_conversion(indio_dev, chan, val);
    case IIO_CHAN_INFO_SCALE:
        scale_uv = (st->int_vref_mv * 100000 * st->gain)
            >> (chan->scan_type.realbits - 1);
        *val =  scale_uv / 100000;
        *val2 = (scale_uv % 100000) * 10;
        return IIO_VAL_INT_PLUS_MICRO;
    case IIO_CHAN_INFO_OFFSET:
        *val -= (1 << (chan->scan_type.realbits - 1));
        return IIO_VAL_INT;
    }

    return -EINVAL;
}

static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
    unsigned int raw_sample)
{
    struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
    const struct ad7780_chip_info *chip_info = st->chip_info;

    if ((raw_sample & AD7780_ERR) ||
        ((raw_sample & chip_info->pattern_mask) != chip_info->pattern))
        return -EIO;

    if (raw_sample & AD7780_GAIN)
        st->gain = 1;
    else
        st->gain = 128;

    return 0;
}

static const struct ad_sigma_delta_info ad7780_sigma_delta_info = {
    .set_mode = ad7780_set_mode,
    .postprocess_sample = ad7780_postprocess_sample,
    .has_registers = false,
};

#define AD7780_CHANNEL(bits, wordsize) \
    AD_SD_CHANNEL(1, 0, 0, bits, 32, wordsize - bits)

static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
    [ID_AD7170] = {
        .channel = AD7780_CHANNEL(12, 24),
        .pattern = 0x5,
        .pattern_mask = 0x7,
    },
    [ID_AD7171] = {
        .channel = AD7780_CHANNEL(16, 24),
        .pattern = 0x5,
        .pattern_mask = 0x7,
    },
    [ID_AD7780] = {
        .channel = AD7780_CHANNEL(24, 32),
        .pattern = 0x1,
        .pattern_mask = 0x3,
    },
    [ID_AD7781] = {
        .channel = AD7780_CHANNEL(20, 32),
        .pattern = 0x1,
        .pattern_mask = 0x3,
    },
};

static const struct iio_info ad7780_info = {
    .read_raw = &ad7780_read_raw,
    .driver_module = THIS_MODULE,
};

static int __devinit ad7780_probe(struct spi_device *spi)
{
    struct ad7780_platform_data *pdata = spi->dev.platform_data;
    struct ad7780_state *st;
    struct iio_dev *indio_dev;
    int ret, voltage_uv = 0;

    indio_dev = iio_device_alloc(sizeof(*st));
    if (indio_dev == NULL)
        return -ENOMEM;

    st = iio_priv(indio_dev);
    st->gain = 1;

    ad_sd_init(&st->sd, indio_dev, spi, &ad7780_sigma_delta_info);

    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 =
        &ad7780_chip_info_tbl[spi_get_device_id(spi)->driver_data];

    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");

    spi_set_drvdata(spi, indio_dev);

    indio_dev->dev.parent = &spi->dev;
    indio_dev->name = spi_get_device_id(spi)->name;
    indio_dev->modes = INDIO_DIRECT_MODE;
    indio_dev->channels = &st->chip_info->channel;
    indio_dev->num_channels = 1;
    indio_dev->info = &ad7780_info;

    if (pdata && gpio_is_valid(pdata->gpio_pdrst)) {

        ret = gpio_request_one(pdata->gpio_pdrst, GPIOF_OUT_INIT_LOW,
                   "AD7780 /PDRST");
        if (ret) {
            dev_err(&spi->dev, "failed to request GPIO PDRST\n");
            goto error_disable_reg;
        }
        st->powerdown_gpio = pdata->gpio_pdrst;
    } else {
        st->powerdown_gpio = -1;
    }

    ret = ad_sd_setup_buffer_and_trigger(indio_dev);
    if (ret)
        goto error_free_gpio;

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

    return 0;

error_cleanup_buffer_and_trigger:
    ad_sd_cleanup_buffer_and_trigger(indio_dev);
error_free_gpio:
    if (pdata && gpio_is_valid(pdata->gpio_pdrst))
        gpio_free(pdata->gpio_pdrst);
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 ad7780_remove(struct spi_device *spi)
{
    struct iio_dev *indio_dev = spi_get_drvdata(spi);
    struct ad7780_state *st = iio_priv(indio_dev);

    iio_device_unregister(indio_dev);
    ad_sd_cleanup_buffer_and_trigger(indio_dev);

    if (gpio_is_valid(st->powerdown_gpio))
        gpio_free(st->powerdown_gpio);

    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 ad7780_id[] = {
    {"ad7170", ID_AD7170},
    {"ad7171", ID_AD7171},
    {"ad7780", ID_AD7780},
    {"ad7781", ID_AD7781},
    {}
};
MODULE_DEVICE_TABLE(spi, ad7780_id);

static struct spi_driver ad7780_driver = {
    .driver = {
        .name   = "ad7780",
        .owner  = THIS_MODULE,
    },
    .probe      = ad7780_probe,
    .remove     = __devexit_p(ad7780_remove),
    .id_table   = ad7780_id,
};
module_spi_driver(ad7780_driver);

MODULE_AUTHOR("Michael Hennerich <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD7780 and similar ADCs");
MODULE_LICENSE("GPL v2");