ad7816.c

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/*
 * AD7816 digital temperature sensor driver supporting AD7816/7/8
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/list.h>
#include <linux/spi/spi.h>
#include <linux/module.h>

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

/*
 * AD7816 config masks
 */
#define AD7816_FULL         0x1
#define AD7816_PD           0x2
#define AD7816_CS_MASK          0x7
#define AD7816_CS_MAX           0x4

/*
 * AD7816 temperature masks
 */
#define AD7816_VALUE_OFFSET     6
#define AD7816_BOUND_VALUE_BASE     0x8
#define AD7816_BOUND_VALUE_MIN      -95
#define AD7816_BOUND_VALUE_MAX      152
#define AD7816_TEMP_FLOAT_OFFSET    2
#define AD7816_TEMP_FLOAT_MASK      0x3


/*
 * struct ad7816_chip_info - chip specifc information
 */

struct ad7816_chip_info {
    struct spi_device *spi_dev;
    u16 rdwr_pin;
    u16 convert_pin;
    u16 busy_pin;
    u8  oti_data[AD7816_CS_MAX+1];
    u8  channel_id; /* 0 always be temperature */
    u8  mode;
};

/*
 * ad7816 data access by SPI
 */
static int ad7816_spi_read(struct ad7816_chip_info *chip, u16 *data)
{
    struct spi_device *spi_dev = chip->spi_dev;
    int ret = 0;

    gpio_set_value(chip->rdwr_pin, 1);
    gpio_set_value(chip->rdwr_pin, 0);
    ret = spi_write(spi_dev, &chip->channel_id, sizeof(chip->channel_id));
    if (ret < 0) {
        dev_err(&spi_dev->dev, "SPI channel setting error\n");
        return ret;
    }
    gpio_set_value(chip->rdwr_pin, 1);


    if (chip->mode == AD7816_PD) { /* operating mode 2 */
        gpio_set_value(chip->convert_pin, 1);
        gpio_set_value(chip->convert_pin, 0);
    } else { /* operating mode 1 */
        gpio_set_value(chip->convert_pin, 0);
        gpio_set_value(chip->convert_pin, 1);
    }

    while (gpio_get_value(chip->busy_pin))
        cpu_relax();

    gpio_set_value(chip->rdwr_pin, 0);
    gpio_set_value(chip->rdwr_pin, 1);
    ret = spi_read(spi_dev, (u8 *)data, sizeof(*data));
    if (ret < 0) {
        dev_err(&spi_dev->dev, "SPI data read error\n");
        return ret;
    }

    *data = be16_to_cpu(*data);

    return ret;
}

static int ad7816_spi_write(struct ad7816_chip_info *chip, u8 data)
{
    struct spi_device *spi_dev = chip->spi_dev;
    int ret = 0;

    gpio_set_value(chip->rdwr_pin, 1);
    gpio_set_value(chip->rdwr_pin, 0);
    ret = spi_write(spi_dev, &data, sizeof(data));
    if (ret < 0)
        dev_err(&spi_dev->dev, "SPI oti data write error\n");

    return ret;
}

static ssize_t ad7816_show_mode(struct device *dev,
        struct device_attribute *attr,
        char *buf)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);

    if (chip->mode)
        return sprintf(buf, "power-save\n");
    else
        return sprintf(buf, "full\n");
}

static ssize_t ad7816_store_mode(struct device *dev,
        struct device_attribute *attr,
        const char *buf,
        size_t len)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);

    if (strcmp(buf, "full")) {
        gpio_set_value(chip->rdwr_pin, 1);
        chip->mode = AD7816_FULL;
    } else {
        gpio_set_value(chip->rdwr_pin, 0);
        chip->mode = AD7816_PD;
    }

    return len;
}

static IIO_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR,
        ad7816_show_mode,
        ad7816_store_mode,
        0);

static ssize_t ad7816_show_available_modes(struct device *dev,
        struct device_attribute *attr,
        char *buf)
{
    return sprintf(buf, "full\npower-save\n");
}

static IIO_DEVICE_ATTR(available_modes, S_IRUGO, ad7816_show_available_modes, NULL, 0);

static ssize_t ad7816_show_channel(struct device *dev,
        struct device_attribute *attr,
        char *buf)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);

    return sprintf(buf, "%d\n", chip->channel_id);
}

static ssize_t ad7816_store_channel(struct device *dev,
        struct device_attribute *attr,
        const char *buf,
        size_t len)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);
    unsigned long data;
    int ret;

    ret = strict_strtoul(buf, 10, &data);
    if (ret)
        return -EINVAL;

    if (data > AD7816_CS_MAX && data != AD7816_CS_MASK) {
        dev_err(&chip->spi_dev->dev, "Invalid channel id %lu for %s.\n",
            data, indio_dev->name);
        return -EINVAL;
    } else if (strcmp(indio_dev->name, "ad7818") == 0 && data > 1) {
        dev_err(&chip->spi_dev->dev,
            "Invalid channel id %lu for ad7818.\n", data);
        return -EINVAL;
    } else if (strcmp(indio_dev->name, "ad7816") == 0 && data > 0) {
        dev_err(&chip->spi_dev->dev,
            "Invalid channel id %lu for ad7816.\n", data);
        return -EINVAL;
    }

    chip->channel_id = data;

    return len;
}

static IIO_DEVICE_ATTR(channel, S_IRUGO | S_IWUSR,
        ad7816_show_channel,
        ad7816_store_channel,
        0);


static ssize_t ad7816_show_value(struct device *dev,
        struct device_attribute *attr,
        char *buf)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);
    u16 data;
    s8 value;
    int ret;

    ret = ad7816_spi_read(chip, &data);
    if (ret)
        return -EIO;

    data >>= AD7816_VALUE_OFFSET;

    if (chip->channel_id == 0) {
        value = (s8)((data >> AD7816_TEMP_FLOAT_OFFSET) - 103);
        data &= AD7816_TEMP_FLOAT_MASK;
        if (value < 0)
            data = (1 << AD7816_TEMP_FLOAT_OFFSET) - data;
        return sprintf(buf, "%d.%.2d\n", value, data * 25);
    } else
        return sprintf(buf, "%u\n", data);
}

static IIO_DEVICE_ATTR(value, S_IRUGO, ad7816_show_value, NULL, 0);

static struct attribute *ad7816_attributes[] = {
    &iio_dev_attr_available_modes.dev_attr.attr,
    &iio_dev_attr_mode.dev_attr.attr,
    &iio_dev_attr_channel.dev_attr.attr,
    &iio_dev_attr_value.dev_attr.attr,
    NULL,
};

static const struct attribute_group ad7816_attribute_group = {
    .attrs = ad7816_attributes,
};

/*
 * temperature bound events
 */

#define IIO_EVENT_CODE_AD7816_OTI IIO_UNMOD_EVENT_CODE(IIO_TEMP,    \
                               0,       \
                               IIO_EV_TYPE_THRESH, \
                               IIO_EV_DIR_FALLING)

static irqreturn_t ad7816_event_handler(int irq, void *private)
{
    iio_push_event(private, IIO_EVENT_CODE_AD7816_OTI, iio_get_time_ns());
    return IRQ_HANDLED;
}

static ssize_t ad7816_show_oti(struct device *dev,
        struct device_attribute *attr,
        char *buf)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);
    int value;

    if (chip->channel_id > AD7816_CS_MAX) {
        dev_err(dev, "Invalid oti channel id %d.\n", chip->channel_id);
        return -EINVAL;
    } else if (chip->channel_id == 0) {
        value = AD7816_BOUND_VALUE_MIN +
            (chip->oti_data[chip->channel_id] -
            AD7816_BOUND_VALUE_BASE);
        return sprintf(buf, "%d\n", value);
    } else
        return sprintf(buf, "%u\n", chip->oti_data[chip->channel_id]);
}

static inline ssize_t ad7816_set_oti(struct device *dev,
        struct device_attribute *attr,
        const char *buf,
        size_t len)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);
    long value;
    u8 data;
    int ret;

    ret = strict_strtol(buf, 10, &value);

    if (chip->channel_id > AD7816_CS_MAX) {
        dev_err(dev, "Invalid oti channel id %d.\n", chip->channel_id);
        return -EINVAL;
    } else if (chip->channel_id == 0) {
        if (ret || value < AD7816_BOUND_VALUE_MIN ||
            value > AD7816_BOUND_VALUE_MAX)
            return -EINVAL;

        data = (u8)(value - AD7816_BOUND_VALUE_MIN +
            AD7816_BOUND_VALUE_BASE);
    } else {
        if (ret || value < AD7816_BOUND_VALUE_BASE || value > 255)
            return -EINVAL;

        data = (u8)value;
    }

    ret = ad7816_spi_write(chip, data);
    if (ret)
        return -EIO;

    chip->oti_data[chip->channel_id] = data;

    return len;
}

static IIO_DEVICE_ATTR(oti, S_IRUGO | S_IWUSR,
               ad7816_show_oti, ad7816_set_oti, 0);

static struct attribute *ad7816_event_attributes[] = {
    &iio_dev_attr_oti.dev_attr.attr,
    NULL,
};

static struct attribute_group ad7816_event_attribute_group = {
    .attrs = ad7816_event_attributes,
    .name = "events",
};

static const struct iio_info ad7816_info = {
    .attrs = &ad7816_attribute_group,
    .event_attrs = &ad7816_event_attribute_group,
    .driver_module = THIS_MODULE,
};

/*
 * device probe and remove
 */

static int __devinit ad7816_probe(struct spi_device *spi_dev)
{
    struct ad7816_chip_info *chip;
    struct iio_dev *indio_dev;
    unsigned short *pins = spi_dev->dev.platform_data;
    int ret = 0;
    int i;

    if (!pins) {
        dev_err(&spi_dev->dev, "No necessary GPIO platform data.\n");
        return -EINVAL;
    }

    indio_dev = iio_device_alloc(sizeof(*chip));
    if (indio_dev == NULL) {
        ret = -ENOMEM;
        goto error_ret;
    }
    chip = iio_priv(indio_dev);
    /* this is only used for device removal purposes */
    dev_set_drvdata(&spi_dev->dev, indio_dev);

    chip->spi_dev = spi_dev;
    for (i = 0; i <= AD7816_CS_MAX; i++)
        chip->oti_data[i] = 203;
    chip->rdwr_pin = pins[0];
    chip->convert_pin = pins[1];
    chip->busy_pin = pins[2];

    ret = gpio_request(chip->rdwr_pin, spi_get_device_id(spi_dev)->name);
    if (ret) {
        dev_err(&spi_dev->dev, "Fail to request rdwr gpio PIN %d.\n",
            chip->rdwr_pin);
        goto error_free_device;
    }
    gpio_direction_input(chip->rdwr_pin);
    ret = gpio_request(chip->convert_pin, spi_get_device_id(spi_dev)->name);
    if (ret) {
        dev_err(&spi_dev->dev, "Fail to request convert gpio PIN %d.\n",
            chip->convert_pin);
        goto error_free_gpio_rdwr;
    }
    gpio_direction_input(chip->convert_pin);
    ret = gpio_request(chip->busy_pin, spi_get_device_id(spi_dev)->name);
    if (ret) {
        dev_err(&spi_dev->dev, "Fail to request busy gpio PIN %d.\n",
            chip->busy_pin);
        goto error_free_gpio_convert;
    }
    gpio_direction_input(chip->busy_pin);

    indio_dev->name = spi_get_device_id(spi_dev)->name;
    indio_dev->dev.parent = &spi_dev->dev;
    indio_dev->info = &ad7816_info;
    indio_dev->modes = INDIO_DIRECT_MODE;

    if (spi_dev->irq) {
        /* Only low trigger is supported in ad7816/7/8 */
        ret = request_threaded_irq(spi_dev->irq,
                       NULL,
                       &ad7816_event_handler,
                       IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                       indio_dev->name,
                       indio_dev);
        if (ret)
            goto error_free_gpio;
    }

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

    dev_info(&spi_dev->dev, "%s temperature sensor and ADC registered.\n",
             indio_dev->name);

    return 0;
error_free_irq:
    free_irq(spi_dev->irq, indio_dev);
error_free_gpio:
    gpio_free(chip->busy_pin);
error_free_gpio_convert:
    gpio_free(chip->convert_pin);
error_free_gpio_rdwr:
    gpio_free(chip->rdwr_pin);
error_free_device:
    iio_device_free(indio_dev);
error_ret:
    return ret;
}

static int __devexit ad7816_remove(struct spi_device *spi_dev)
{
    struct iio_dev *indio_dev = dev_get_drvdata(&spi_dev->dev);
    struct ad7816_chip_info *chip = iio_priv(indio_dev);

    iio_device_unregister(indio_dev);
    dev_set_drvdata(&spi_dev->dev, NULL);
    if (spi_dev->irq)
        free_irq(spi_dev->irq, indio_dev);
    gpio_free(chip->busy_pin);
    gpio_free(chip->convert_pin);
    gpio_free(chip->rdwr_pin);
    iio_device_free(indio_dev);

    return 0;
}

static const struct spi_device_id ad7816_id[] = {
    { "ad7816", 0 },
    { "ad7817", 0 },
    { "ad7818", 0 },
    {}
};

MODULE_DEVICE_TABLE(spi, ad7816_id);

static struct spi_driver ad7816_driver = {
    .driver = {
        .name = "ad7816",
        .owner = THIS_MODULE,
    },
    .probe = ad7816_probe,
    .remove = __devexit_p(ad7816_remove),
    .id_table = ad7816_id,
};
module_spi_driver(ad7816_driver);

MODULE_AUTHOR("Sonic Zhang <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD7816/7/8 digital"
            " temperature sensor driver");
MODULE_LICENSE("GPL v2");