iio_hwmon.c

Go to the documentation of this file.

/* Hwmon client for industrial I/O devices
 *
 * Copyright (c) 2011 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/iio/consumer.h>
#include <linux/iio/types.h>

struct iio_hwmon_state {
    struct iio_channel *channels;
    int num_channels;
    struct device *hwmon_dev;
    struct attribute_group attr_group;
    struct attribute **attrs;
};

/*
 * Assumes that IIO and hwmon operate in the same base units.
 * This is supposed to be true, but needs verification for
 * new channel types.
 */
static ssize_t iio_hwmon_read_val(struct device *dev,
                  struct device_attribute *attr,
                  char *buf)
{
    int result;
    int ret;
    struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
    struct iio_hwmon_state *state = dev_get_drvdata(dev);

    ret = iio_read_channel_processed(&state->channels[sattr->index],
                    &result);
    if (ret < 0)
        return ret;

    return sprintf(buf, "%d\n", result);
}

static void iio_hwmon_free_attrs(struct iio_hwmon_state *st)
{
    int i;
    struct sensor_device_attribute *a;
    for (i = 0; i < st->num_channels; i++)
        if (st->attrs[i]) {
            a = to_sensor_dev_attr(
                container_of(st->attrs[i],
                         struct device_attribute,
                         attr));
            kfree(a);
        }
}

static int __devinit iio_hwmon_probe(struct platform_device *pdev)
{
    struct iio_hwmon_state *st;
    struct sensor_device_attribute *a;
    int ret, i;
    int in_i = 1, temp_i = 1, curr_i = 1;
    enum iio_chan_type type;

    st = kzalloc(sizeof(*st), GFP_KERNEL);
    if (st == NULL) {
        ret = -ENOMEM;
        goto error_ret;
    }

    st->channels = iio_channel_get_all(dev_name(&pdev->dev));
    if (IS_ERR(st->channels)) {
        ret = PTR_ERR(st->channels);
        goto error_free_state;
    }

    /* count how many attributes we have */
    while (st->channels[st->num_channels].indio_dev)
        st->num_channels++;

    st->attrs = kzalloc(sizeof(st->attrs) * (st->num_channels + 1),
                GFP_KERNEL);
    if (st->attrs == NULL) {
        ret = -ENOMEM;
        goto error_release_channels;
    }
    for (i = 0; i < st->num_channels; i++) {
        a = kzalloc(sizeof(*a), GFP_KERNEL);
        if (a == NULL) {
            ret = -ENOMEM;
            goto error_free_attrs;
        }

        sysfs_attr_init(&a->dev_attr.attr);
        ret = iio_get_channel_type(&st->channels[i], &type);
        if (ret < 0) {
            kfree(a);
            goto error_free_attrs;
        }
        switch (type) {
        case IIO_VOLTAGE:
            a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
                              "in%d_input",
                              in_i++);
            break;
        case IIO_TEMP:
            a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
                              "temp%d_input",
                              temp_i++);
            break;
        case IIO_CURRENT:
            a->dev_attr.attr.name = kasprintf(GFP_KERNEL,
                              "curr%d_input",
                              curr_i++);
            break;
        default:
            ret = -EINVAL;
            kfree(a);
            goto error_free_attrs;
        }
        if (a->dev_attr.attr.name == NULL) {
            kfree(a);
            ret = -ENOMEM;
            goto error_free_attrs;
        }
        a->dev_attr.show = iio_hwmon_read_val;
        a->dev_attr.attr.mode = S_IRUGO;
        a->index = i;
        st->attrs[i] = &a->dev_attr.attr;
    }

    st->attr_group.attrs = st->attrs;
    platform_set_drvdata(pdev, st);
    ret = sysfs_create_group(&pdev->dev.kobj, &st->attr_group);
    if (ret < 0)
        goto error_free_attrs;

    st->hwmon_dev = hwmon_device_register(&pdev->dev);
    if (IS_ERR(st->hwmon_dev)) {
        ret = PTR_ERR(st->hwmon_dev);
        goto error_remove_group;
    }
    return 0;

error_remove_group:
    sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
error_free_attrs:
    iio_hwmon_free_attrs(st);
    kfree(st->attrs);
error_release_channels:
    iio_channel_release_all(st->channels);
error_free_state:
    kfree(st);
error_ret:
    return ret;
}

static int __devexit iio_hwmon_remove(struct platform_device *pdev)
{
    struct iio_hwmon_state *st = platform_get_drvdata(pdev);

    hwmon_device_unregister(st->hwmon_dev);
    sysfs_remove_group(&pdev->dev.kobj, &st->attr_group);
    iio_hwmon_free_attrs(st);
    kfree(st->attrs);
    iio_channel_release_all(st->channels);

    return 0;
}

static struct platform_driver __refdata iio_hwmon_driver = {
    .driver = {
        .name = "iio_hwmon",
        .owner = THIS_MODULE,
    },
    .probe = iio_hwmon_probe,
    .remove = __devexit_p(iio_hwmon_remove),
};

module_platform_driver(iio_hwmon_driver);

MODULE_AUTHOR("Jonathan Cameron <[email protected]>");
MODULE_DESCRIPTION("IIO to hwmon driver");
MODULE_LICENSE("GPL v2");