tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 hwmon.c - part of lm_sensors, Linux kernel modules for hardware monitoring
3
4 This file defines the sysfs class "hwmon", for use by sensors drivers.
5
6 Copyright (C) 2005 Mark M. Hoffman <mhoffman@lightlink.com>
7
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; version 2 of the License.
11*/
12
13#include <linux/module.h>
14#include <linux/device.h>
15#include <linux/err.h>
16#include <linux/kdev_t.h>
17#include <linux/idr.h>
18#include <linux/hwmon.h>
19#include <linux/gfp.h>
20#include <linux/spinlock.h>
21
22#define HWMON_ID_PREFIX "hwmon"
23#define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
24
25static struct class *hwmon_class;
26
27static DEFINE_IDR(hwmon_idr);
28static DEFINE_SPINLOCK(idr_lock);
29
30/**
31 * hwmon_device_register - register w/ hwmon
32 * @dev: the device to register
33 *
34 * hwmon_device_unregister() must be called when the device is no
35 * longer needed.
36 *
37 * Returns the pointer to the new device.
38 */
39struct device *hwmon_device_register(struct device *dev)
40{
41 struct device *hwdev;
42 int id, err;
43
44again:
45 if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))
46 return ERR_PTR(-ENOMEM);
47
48 spin_lock(&idr_lock);
49 err = idr_get_new(&hwmon_idr, NULL, &id);
50 spin_unlock(&idr_lock);
51
52 if (unlikely(err == -EAGAIN))
53 goto again;
54 else if (unlikely(err))
55 return ERR_PTR(err);
56
57 id = id & MAX_ID_MASK;
58 hwdev = device_create(hwmon_class, dev, MKDEV(0, 0), NULL,
59 HWMON_ID_FORMAT, id);
60
61 if (IS_ERR(hwdev)) {
62 spin_lock(&idr_lock);
63 idr_remove(&hwmon_idr, id);
64 spin_unlock(&idr_lock);
65 }
66
67 return hwdev;
68}
69
70/**
71 * hwmon_device_unregister - removes the previously registered class device
72 *
73 * @dev: the class device to destroy
74 */
75void hwmon_device_unregister(struct device *dev)
76{
77 int id;
78
79 if (likely(sscanf(dev_name(dev), HWMON_ID_FORMAT, &id) == 1)) {
80 device_unregister(dev);
81 spin_lock(&idr_lock);
82 idr_remove(&hwmon_idr, id);
83 spin_unlock(&idr_lock);
84 } else
85 dev_dbg(dev->parent,
86 "hwmon_device_unregister() failed: bad class ID!\n");
87}
88
89static int __init hwmon_init(void)
90{
91 hwmon_class = class_create(THIS_MODULE, "hwmon");
92 if (IS_ERR(hwmon_class)) {
93 printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");
94 return PTR_ERR(hwmon_class);
95 }
96 return 0;
97}
98
99static void __exit hwmon_exit(void)
100{
101 class_destroy(hwmon_class);
102}
103
104subsys_initcall(hwmon_init);
105module_exit(hwmon_exit);
106
107EXPORT_SYMBOL_GPL(hwmon_device_register);
108EXPORT_SYMBOL_GPL(hwmon_device_unregister);
109
110MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
111MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
112MODULE_LICENSE("GPL");
113