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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 sysfs class
* @dev: the device to register
*
* hwmon_device_unregister() must be called when the class device is no
* longer needed.
*
* Returns the pointer to the new struct class device.
*/
struct class_device *hwmon_device_register(struct device *dev)
{
struct class_device *cdev;
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;
cdev = class_device_create(hwmon_class, NULL, MKDEV(0,0), dev,
HWMON_ID_FORMAT, id);
if (IS_ERR(cdev)) {
spin_lock(&idr_lock);
idr_remove(&hwmon_idr, id);
spin_unlock(&idr_lock);
}
return cdev;
}
/**
* hwmon_device_unregister - removes the previously registered class device
*
* @cdev: the class device to destroy
*/
void hwmon_device_unregister(struct class_device *cdev)
{
int id;
if (likely(sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1)) {
class_device_unregister(cdev);
spin_lock(&idr_lock);
idr_remove(&hwmon_idr, id);
spin_unlock(&idr_lock);
} else
dev_dbg(cdev->dev,
"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);
}
module_init(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");
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