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>
18 #include <linux/slab.h>
19 #include <linux/workqueue.h>
24 static DEFINE_IDA(rtc_ida);
25 struct class *rtc_class;
27 static void rtc_device_release(struct device *dev)
29 struct rtc_device *rtc = to_rtc_device(dev);
30 ida_simple_remove(&rtc_ida, rtc->id);
34 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
35 /* Result of the last RTC to system clock attempt. */
36 int rtc_hctosys_ret = -ENODEV;
39 #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
41 * On suspend(), measure the delta between one RTC and the
42 * system's wall clock; restore it on resume().
45 static struct timespec old_rtc, old_system, old_delta;
48 static int rtc_suspend(struct device *dev, pm_message_t mesg)
50 struct rtc_device *rtc = to_rtc_device(dev);
52 struct timespec delta, delta_delta;
54 if (has_persistent_clock())
57 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
60 /* snapshot the current RTC and system time at suspend*/
61 rtc_read_time(rtc, &tm);
62 getnstimeofday(&old_system);
63 rtc_tm_to_time(&tm, &old_rtc.tv_sec);
67 * To avoid drift caused by repeated suspend/resumes,
68 * which each can add ~1 second drift error,
69 * try to compensate so the difference in system time
70 * and rtc time stays close to constant.
72 delta = timespec_sub(old_system, old_rtc);
73 delta_delta = timespec_sub(delta, old_delta);
74 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
76 * if delta_delta is too large, assume time correction
77 * has occured and set old_delta to the current delta.
81 /* Otherwise try to adjust old_system to compensate */
82 old_system = timespec_sub(old_system, delta_delta);
88 static int rtc_resume(struct device *dev)
90 struct rtc_device *rtc = to_rtc_device(dev);
92 struct timespec new_system, new_rtc;
93 struct timespec sleep_time;
95 if (has_persistent_clock())
98 rtc_hctosys_ret = -ENODEV;
99 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
102 /* snapshot the current rtc and system time at resume */
103 getnstimeofday(&new_system);
104 rtc_read_time(rtc, &tm);
105 if (rtc_valid_tm(&tm) != 0) {
106 pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev));
109 rtc_tm_to_time(&tm, &new_rtc.tv_sec);
112 if (new_rtc.tv_sec < old_rtc.tv_sec) {
113 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
117 /* calculate the RTC time delta (sleep time)*/
118 sleep_time = timespec_sub(new_rtc, old_rtc);
121 * Since these RTC suspend/resume handlers are not called
122 * at the very end of suspend or the start of resume,
123 * some run-time may pass on either sides of the sleep time
124 * so subtract kernel run-time between rtc_suspend to rtc_resume
125 * to keep things accurate.
127 sleep_time = timespec_sub(sleep_time,
128 timespec_sub(new_system, old_system));
130 if (sleep_time.tv_sec >= 0)
131 timekeeping_inject_sleeptime(&sleep_time);
137 #define rtc_suspend NULL
138 #define rtc_resume NULL
143 * rtc_device_register - register w/ RTC class
144 * @dev: the device to register
146 * rtc_device_unregister() must be called when the class device is no
149 * Returns the pointer to the new struct class device.
151 struct rtc_device *rtc_device_register(const char *name, struct device *dev,
152 const struct rtc_class_ops *ops,
153 struct module *owner)
155 struct rtc_device *rtc;
156 struct rtc_wkalrm alrm;
159 id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
165 rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
175 rtc->max_user_freq = 64;
176 rtc->dev.parent = dev;
177 rtc->dev.class = rtc_class;
178 rtc->dev.release = rtc_device_release;
180 mutex_init(&rtc->ops_lock);
181 spin_lock_init(&rtc->irq_lock);
182 spin_lock_init(&rtc->irq_task_lock);
183 init_waitqueue_head(&rtc->irq_queue);
185 /* Init timerqueue */
186 timerqueue_init_head(&rtc->timerqueue);
187 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
189 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
191 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
193 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
194 rtc->pie_timer.function = rtc_pie_update_irq;
195 rtc->pie_enabled = 0;
197 /* Check to see if there is an ALARM already set in hw */
198 err = __rtc_read_alarm(rtc, &alrm);
200 if (!err && !rtc_valid_tm(&alrm.time))
201 rtc_initialize_alarm(rtc, &alrm);
203 strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
204 dev_set_name(&rtc->dev, "rtc%d", id);
206 rtc_dev_prepare(rtc);
208 err = device_register(&rtc->dev);
210 put_device(&rtc->dev);
214 rtc_dev_add_device(rtc);
215 rtc_sysfs_add_device(rtc);
216 rtc_proc_add_device(rtc);
218 dev_info(dev, "rtc core: registered %s as %s\n",
219 rtc->name, dev_name(&rtc->dev));
227 ida_simple_remove(&rtc_ida, id);
230 dev_err(dev, "rtc core: unable to register %s, err = %d\n",
234 EXPORT_SYMBOL_GPL(rtc_device_register);
238 * rtc_device_unregister - removes the previously registered RTC class device
240 * @rtc: the RTC class device to destroy
242 void rtc_device_unregister(struct rtc_device *rtc)
244 if (get_device(&rtc->dev) != NULL) {
245 mutex_lock(&rtc->ops_lock);
246 /* remove innards of this RTC, then disable it, before
247 * letting any rtc_class_open() users access it again
249 rtc_sysfs_del_device(rtc);
250 rtc_dev_del_device(rtc);
251 rtc_proc_del_device(rtc);
252 device_unregister(&rtc->dev);
254 mutex_unlock(&rtc->ops_lock);
255 put_device(&rtc->dev);
258 EXPORT_SYMBOL_GPL(rtc_device_unregister);
260 static int __init rtc_init(void)
262 rtc_class = class_create(THIS_MODULE, "rtc");
263 if (IS_ERR(rtc_class)) {
264 printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
265 return PTR_ERR(rtc_class);
267 rtc_class->suspend = rtc_suspend;
268 rtc_class->resume = rtc_resume;
270 rtc_sysfs_init(rtc_class);
274 static void __exit rtc_exit(void)
277 class_destroy(rtc_class);
278 ida_destroy(&rtc_ida);
281 subsys_initcall(rtc_init);
282 module_exit(rtc_exit);
284 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
285 MODULE_DESCRIPTION("RTC class support");
286 MODULE_LICENSE("GPL");