ad7314.c

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/*
 * AD7314 digital temperature sensor driver for AD7314, ADT7301 and ADT7302
 *
 * Copyright 2010 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 *
 * Conversion to hwmon from IIO done by Jonathan Cameron <[email protected]>
 */
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/spi/spi.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>

/*
 * AD7314 temperature masks
 */
#define AD7314_TEMP_MASK        0x7FE0
#define AD7314_TEMP_SHIFT       5

/*
 * ADT7301 and ADT7302 temperature masks
 */
#define ADT7301_TEMP_MASK       0x3FFF

enum ad7314_variant {
    adt7301,
    adt7302,
    ad7314,
};

struct ad7314_data {
    struct spi_device   *spi_dev;
    struct device       *hwmon_dev;
    u16 rx ____cacheline_aligned;
};

static int ad7314_spi_read(struct ad7314_data *chip)
{
    int ret;

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

    return be16_to_cpu(chip->rx);
}

static ssize_t ad7314_show_temperature(struct device *dev,
        struct device_attribute *attr,
        char *buf)
{
    struct ad7314_data *chip = dev_get_drvdata(dev);
    s16 data;
    int ret;

    ret = ad7314_spi_read(chip);
    if (ret < 0)
        return ret;
    switch (spi_get_device_id(chip->spi_dev)->driver_data) {
    case ad7314:
        data = (ret & AD7314_TEMP_MASK) >> AD7314_TEMP_SHIFT;
        data = (data << 6) >> 6;

        return sprintf(buf, "%d\n", 250 * data);
    case adt7301:
    case adt7302:
        /*
         * Documented as a 13 bit twos complement register
         * with a sign bit - which is a 14 bit 2's complement
         * register.  1lsb - 31.25 milli degrees centigrade
         */
        data = ret & ADT7301_TEMP_MASK;
        data = (data << 2) >> 2;

        return sprintf(buf, "%d\n",
                   DIV_ROUND_CLOSEST(data * 3125, 100));
    default:
        return -EINVAL;
    }
}

static ssize_t ad7314_show_name(struct device *dev,
                struct device_attribute *devattr, char *buf)
{
    return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
}

static DEVICE_ATTR(name, S_IRUGO, ad7314_show_name, NULL);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
              ad7314_show_temperature, NULL, 0);

static struct attribute *ad7314_attributes[] = {
    &dev_attr_name.attr,
    &sensor_dev_attr_temp1_input.dev_attr.attr,
    NULL,
};

static const struct attribute_group ad7314_group = {
    .attrs = ad7314_attributes,
};

static int __devinit ad7314_probe(struct spi_device *spi_dev)
{
    int ret;
    struct ad7314_data *chip;

    chip = devm_kzalloc(&spi_dev->dev, sizeof(*chip), GFP_KERNEL);
    if (chip == NULL)
        return -ENOMEM;

    dev_set_drvdata(&spi_dev->dev, chip);

    ret = sysfs_create_group(&spi_dev->dev.kobj, &ad7314_group);
    if (ret < 0)
        return ret;

    chip->hwmon_dev = hwmon_device_register(&spi_dev->dev);
    if (IS_ERR(chip->hwmon_dev)) {
        ret = PTR_ERR(chip->hwmon_dev);
        goto error_remove_group;
    }
    chip->spi_dev = spi_dev;

    return 0;
error_remove_group:
    sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);
    return ret;
}

static int __devexit ad7314_remove(struct spi_device *spi_dev)
{
    struct ad7314_data *chip = dev_get_drvdata(&spi_dev->dev);

    hwmon_device_unregister(chip->hwmon_dev);
    sysfs_remove_group(&spi_dev->dev.kobj, &ad7314_group);

    return 0;
}

static const struct spi_device_id ad7314_id[] = {
    { "adt7301", adt7301 },
    { "adt7302", adt7302 },
    { "ad7314", ad7314 },
    { }
};
MODULE_DEVICE_TABLE(spi, ad7314_id);

static struct spi_driver ad7314_driver = {
    .driver = {
        .name = "ad7314",
        .owner = THIS_MODULE,
    },
    .probe = ad7314_probe,
    .remove = __devexit_p(ad7314_remove),
    .id_table = ad7314_id,
};

module_spi_driver(ad7314_driver);

MODULE_AUTHOR("Sonic Zhang <[email protected]>");
MODULE_DESCRIPTION("Analog Devices AD7314, ADT7301 and ADT7302 digital"
            " temperature sensor driver");
MODULE_LICENSE("GPL v2");