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/*

    hwmon.c - part of lm_sensors, Linux kernel modules for hardware monitoring

    This file defines the sysfs class "hwmon", for use by sensors drivers.

    Copyright (C) 2005 Mark M. Hoffman <mhoffman@lightlink.com>

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; version 2 of the License.

*/

#include <linux/module.h>

#include <linux/device.h>

#include <linux/err.h>

#include <linux/kdev_t.h>

#include <linux/idr.h>

#include <linux/hwmon.h>

#include <linux/gfp.h>

#include <linux/spinlock.h>

#define HWMON_ID_PREFIX "hwmon"

#define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"

static struct class *hwmon_class;

static DEFINE_IDR(hwmon_idr);

static DEFINE_SPINLOCK(idr_lock);

/**

 * hwmon_device_register - register w/ hwmon

 * @dev: the device to register

 *

 * hwmon_device_unregister() must be called when the device is no

 * longer needed.

 *

 * Returns the pointer to the new device.

 */

struct device *hwmon_device_register(struct device *dev)

{

        struct device *hwdev;

        int id, err;

again:

        if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))

                return ERR_PTR(-ENOMEM);

        spin_lock(&idr_lock);

        err = idr_get_new(&hwmon_idr, NULL, &id);

        spin_unlock(&idr_lock);

        if (unlikely(err == -EAGAIN))

                goto again;

        else if (unlikely(err))

                return ERR_PTR(err);

        id = id & MAX_ID_MASK;

        hwdev = device_create(hwmon_class, dev, MKDEV(0,0), HWMON_ID_FORMAT, id);

        if (IS_ERR(hwdev)) {

                spin_lock(&idr_lock);

                idr_remove(&hwmon_idr, id);

                spin_unlock(&idr_lock);

        }

        return hwdev;

}

/**

 * hwmon_device_unregister - removes the previously registered class device

 *

 * @dev: the class device to destroy

 */

void hwmon_device_unregister(struct device *dev)

{

        int id;

        if (likely(sscanf(dev->bus_id, HWMON_ID_FORMAT, &id) == 1)) {

                device_unregister(dev);

                spin_lock(&idr_lock);

                idr_remove(&hwmon_idr, id);

                spin_unlock(&idr_lock);

        } else

                dev_dbg(dev->parent,

                        "hwmon_device_unregister() failed: bad class ID!\n");

}

static int __init hwmon_init(void)

{

        hwmon_class = class_create(THIS_MODULE, "hwmon");

        if (IS_ERR(hwmon_class)) {

                printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");

                return PTR_ERR(hwmon_class);

        }

        return 0;

}

static void __exit hwmon_exit(void)

{

        class_destroy(hwmon_class);

}

subsys_initcall(hwmon_init);

module_exit(hwmon_exit);

EXPORT_SYMBOL_GPL(hwmon_device_register);

EXPORT_SYMBOL_GPL(hwmon_device_unregister);

MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");

MODULE_DESCRIPTION("hardware monitoring sysfs/class support");

MODULE_LICENSE("GPL");