ext4: fix undefined behavior in ext4_fill_flex_info()
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / rtc / class.c
blob40845c7e93221c7a13a236619ab8225e9638e9ca
1 /*
2 * RTC subsystem, base class
4 * Copyright (C) 2005 Tower Technologies
5 * Author: Alessandro Zummo <a.zummo@towertech.it>
7 * class skeleton from drivers/hwmon/hwmon.c
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
14 #include <linux/module.h>
15 #include <linux/rtc.h>
16 #include <linux/kdev_t.h>
17 #include <linux/idr.h>
19 #include "rtc-core.h"
22 static DEFINE_IDR(rtc_idr);
23 static DEFINE_MUTEX(idr_lock);
24 struct class *rtc_class;
26 static void rtc_device_release(struct device *dev)
28 struct rtc_device *rtc = to_rtc_device(dev);
29 mutex_lock(&idr_lock);
30 idr_remove(&rtc_idr, rtc->id);
31 mutex_unlock(&idr_lock);
32 kfree(rtc);
35 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
38 * On suspend(), measure the delta between one RTC and the
39 * system's wall clock; restore it on resume().
42 static struct timespec delta;
43 static time_t oldtime;
45 static int rtc_suspend(struct device *dev, pm_message_t mesg)
47 struct rtc_device *rtc = to_rtc_device(dev);
48 struct rtc_time tm;
49 struct timespec ts = current_kernel_time();
51 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
52 return 0;
54 rtc_read_time(rtc, &tm);
55 rtc_tm_to_time(&tm, &oldtime);
57 /* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
58 set_normalized_timespec(&delta,
59 ts.tv_sec - oldtime,
60 ts.tv_nsec - (NSEC_PER_SEC >> 1));
62 return 0;
65 static int rtc_resume(struct device *dev)
67 struct rtc_device *rtc = to_rtc_device(dev);
68 struct rtc_time tm;
69 time_t newtime;
70 struct timespec time;
72 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
73 return 0;
75 rtc_read_time(rtc, &tm);
76 if (rtc_valid_tm(&tm) != 0) {
77 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev));
78 return 0;
80 rtc_tm_to_time(&tm, &newtime);
81 if (newtime <= oldtime) {
82 if (newtime < oldtime)
83 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
84 return 0;
87 /* restore wall clock using delta against this RTC;
88 * adjust again for avg 1/2 second RTC sampling error
90 set_normalized_timespec(&time,
91 newtime + delta.tv_sec,
92 (NSEC_PER_SEC >> 1) + delta.tv_nsec);
93 do_settimeofday(&time);
95 return 0;
98 #else
99 #define rtc_suspend NULL
100 #define rtc_resume NULL
101 #endif
105 * rtc_device_register - register w/ RTC class
106 * @dev: the device to register
108 * rtc_device_unregister() must be called when the class device is no
109 * longer needed.
111 * Returns the pointer to the new struct class device.
113 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
114 const struct rtc_class_ops *ops,
115 struct module *owner)
117 struct rtc_device *rtc;
118 int id, err;
120 if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
121 err = -ENOMEM;
122 goto exit;
126 mutex_lock(&idr_lock);
127 err = idr_get_new(&rtc_idr, NULL, &id);
128 mutex_unlock(&idr_lock);
130 if (err < 0)
131 goto exit;
133 id = id & MAX_ID_MASK;
135 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
136 if (rtc == NULL) {
137 err = -ENOMEM;
138 goto exit_idr;
141 rtc->id = id;
142 rtc->ops = ops;
143 rtc->owner = owner;
144 rtc->max_user_freq = 64;
145 rtc->dev.parent = dev;
146 rtc->dev.class = rtc_class;
147 rtc->dev.release = rtc_device_release;
149 mutex_init(&rtc->ops_lock);
150 spin_lock_init(&rtc->irq_lock);
151 spin_lock_init(&rtc->irq_task_lock);
152 init_waitqueue_head(&rtc->irq_queue);
154 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
155 dev_set_name(&rtc->dev, "rtc%d", id);
157 rtc_dev_prepare(rtc);
159 err = device_register(&rtc->dev);
160 if (err)
161 goto exit_kfree;
163 rtc_dev_add_device(rtc);
164 rtc_sysfs_add_device(rtc);
165 rtc_proc_add_device(rtc);
167 dev_info(dev, "rtc core: registered %s as %s\n",
168 rtc->name, dev_name(&rtc->dev));
170 return rtc;
172 exit_kfree:
173 kfree(rtc);
175 exit_idr:
176 mutex_lock(&idr_lock);
177 idr_remove(&rtc_idr, id);
178 mutex_unlock(&idr_lock);
180 exit:
181 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
182 name, err);
183 return ERR_PTR(err);
185 EXPORT_SYMBOL_GPL(rtc_device_register);
189 * rtc_device_unregister - removes the previously registered RTC class device
191 * @rtc: the RTC class device to destroy
193 void rtc_device_unregister(struct rtc_device *rtc)
195 if (get_device(&rtc->dev) != NULL) {
196 mutex_lock(&rtc->ops_lock);
197 /* remove innards of this RTC, then disable it, before
198 * letting any rtc_class_open() users access it again
200 rtc_sysfs_del_device(rtc);
201 rtc_dev_del_device(rtc);
202 rtc_proc_del_device(rtc);
203 device_unregister(&rtc->dev);
204 rtc->ops = NULL;
205 mutex_unlock(&rtc->ops_lock);
206 put_device(&rtc->dev);
209 EXPORT_SYMBOL_GPL(rtc_device_unregister);
211 static int __init rtc_init(void)
213 rtc_class = class_create(THIS_MODULE, "rtc");
214 if (IS_ERR(rtc_class)) {
215 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
216 return PTR_ERR(rtc_class);
218 rtc_class->suspend = rtc_suspend;
219 rtc_class->resume = rtc_resume;
220 rtc_dev_init();
221 rtc_sysfs_init(rtc_class);
222 return 0;
225 static void __exit rtc_exit(void)
227 rtc_dev_exit();
228 class_destroy(rtc_class);
229 idr_destroy(&rtc_idr);
232 subsys_initcall(rtc_init);
233 module_exit(rtc_exit);
235 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
236 MODULE_DESCRIPTION("RTC class support");
237 MODULE_LICENSE("GPL");