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
;
53 if (strcmp(dev_name(&rtc
->dev
), CONFIG_RTC_HCTOSYS_DEVICE
) != 0)
56 /* snapshot the current RTC and system time at suspend*/
57 rtc_read_time(rtc
, &tm
);
58 getnstimeofday(&old_system
);
59 rtc_tm_to_time(&tm
, &old_rtc
.tv_sec
);
63 * To avoid drift caused by repeated suspend/resumes,
64 * which each can add ~1 second drift error,
65 * try to compensate so the difference in system time
66 * and rtc time stays close to constant.
68 delta
= timespec_sub(old_system
, old_rtc
);
69 delta_delta
= timespec_sub(delta
, old_delta
);
70 if (delta_delta
.tv_sec
< -2 || delta_delta
.tv_sec
>= 2) {
72 * if delta_delta is too large, assume time correction
73 * has occured and set old_delta to the current delta.
77 /* Otherwise try to adjust old_system to compensate */
78 old_system
= timespec_sub(old_system
, delta_delta
);
84 static int rtc_resume(struct device
*dev
)
86 struct rtc_device
*rtc
= to_rtc_device(dev
);
88 struct timespec new_system
, new_rtc
;
89 struct timespec sleep_time
;
91 rtc_hctosys_ret
= -ENODEV
;
92 if (strcmp(dev_name(&rtc
->dev
), CONFIG_RTC_HCTOSYS_DEVICE
) != 0)
95 /* snapshot the current rtc and system time at resume */
96 getnstimeofday(&new_system
);
97 rtc_read_time(rtc
, &tm
);
98 if (rtc_valid_tm(&tm
) != 0) {
99 pr_debug("%s: bogus resume time\n", dev_name(&rtc
->dev
));
102 rtc_tm_to_time(&tm
, &new_rtc
.tv_sec
);
105 if (new_rtc
.tv_sec
< old_rtc
.tv_sec
) {
106 pr_debug("%s: time travel!\n", dev_name(&rtc
->dev
));
110 /* calculate the RTC time delta (sleep time)*/
111 sleep_time
= timespec_sub(new_rtc
, old_rtc
);
114 * Since these RTC suspend/resume handlers are not called
115 * at the very end of suspend or the start of resume,
116 * some run-time may pass on either sides of the sleep time
117 * so subtract kernel run-time between rtc_suspend to rtc_resume
118 * to keep things accurate.
120 sleep_time
= timespec_sub(sleep_time
,
121 timespec_sub(new_system
, old_system
));
123 if (sleep_time
.tv_sec
>= 0)
124 timekeeping_inject_sleeptime(&sleep_time
);
130 #define rtc_suspend NULL
131 #define rtc_resume NULL
136 * rtc_device_register - register w/ RTC class
137 * @dev: the device to register
139 * rtc_device_unregister() must be called when the class device is no
142 * Returns the pointer to the new struct class device.
144 struct rtc_device
*rtc_device_register(const char *name
, struct device
*dev
,
145 const struct rtc_class_ops
*ops
,
146 struct module
*owner
)
148 struct rtc_device
*rtc
;
149 struct rtc_wkalrm alrm
;
152 id
= ida_simple_get(&rtc_ida
, 0, 0, GFP_KERNEL
);
158 rtc
= kzalloc(sizeof(struct rtc_device
), GFP_KERNEL
);
168 rtc
->max_user_freq
= 64;
169 rtc
->dev
.parent
= dev
;
170 rtc
->dev
.class = rtc_class
;
171 rtc
->dev
.release
= rtc_device_release
;
173 mutex_init(&rtc
->ops_lock
);
174 spin_lock_init(&rtc
->irq_lock
);
175 spin_lock_init(&rtc
->irq_task_lock
);
176 init_waitqueue_head(&rtc
->irq_queue
);
178 /* Init timerqueue */
179 timerqueue_init_head(&rtc
->timerqueue
);
180 INIT_WORK(&rtc
->irqwork
, rtc_timer_do_work
);
182 rtc_timer_init(&rtc
->aie_timer
, rtc_aie_update_irq
, (void *)rtc
);
184 rtc_timer_init(&rtc
->uie_rtctimer
, rtc_uie_update_irq
, (void *)rtc
);
186 hrtimer_init(&rtc
->pie_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
187 rtc
->pie_timer
.function
= rtc_pie_update_irq
;
188 rtc
->pie_enabled
= 0;
190 /* Check to see if there is an ALARM already set in hw */
191 err
= __rtc_read_alarm(rtc
, &alrm
);
193 if (!err
&& !rtc_valid_tm(&alrm
.time
))
194 rtc_initialize_alarm(rtc
, &alrm
);
196 strlcpy(rtc
->name
, name
, RTC_DEVICE_NAME_SIZE
);
197 dev_set_name(&rtc
->dev
, "rtc%d", id
);
199 rtc_dev_prepare(rtc
);
201 err
= device_register(&rtc
->dev
);
203 put_device(&rtc
->dev
);
207 rtc_dev_add_device(rtc
);
208 rtc_sysfs_add_device(rtc
);
209 rtc_proc_add_device(rtc
);
211 dev_info(dev
, "rtc core: registered %s as %s\n",
212 rtc
->name
, dev_name(&rtc
->dev
));
220 ida_simple_remove(&rtc_ida
, id
);
223 dev_err(dev
, "rtc core: unable to register %s, err = %d\n",
227 EXPORT_SYMBOL_GPL(rtc_device_register
);
231 * rtc_device_unregister - removes the previously registered RTC class device
233 * @rtc: the RTC class device to destroy
235 void rtc_device_unregister(struct rtc_device
*rtc
)
237 if (get_device(&rtc
->dev
) != NULL
) {
238 mutex_lock(&rtc
->ops_lock
);
239 /* remove innards of this RTC, then disable it, before
240 * letting any rtc_class_open() users access it again
242 rtc_sysfs_del_device(rtc
);
243 rtc_dev_del_device(rtc
);
244 rtc_proc_del_device(rtc
);
245 device_unregister(&rtc
->dev
);
247 ida_simple_remove(&rtc_ida
, rtc
->id
);
248 mutex_unlock(&rtc
->ops_lock
);
249 put_device(&rtc
->dev
);
252 EXPORT_SYMBOL_GPL(rtc_device_unregister
);
254 static int __init
rtc_init(void)
256 rtc_class
= class_create(THIS_MODULE
, "rtc");
257 if (IS_ERR(rtc_class
)) {
258 printk(KERN_ERR
"%s: couldn't create class\n", __FILE__
);
259 return PTR_ERR(rtc_class
);
261 rtc_class
->suspend
= rtc_suspend
;
262 rtc_class
->resume
= rtc_resume
;
264 rtc_sysfs_init(rtc_class
);
268 static void __exit
rtc_exit(void)
271 class_destroy(rtc_class
);
272 ida_destroy(&rtc_ida
);
275 subsys_initcall(rtc_init
);
276 module_exit(rtc_exit
);
278 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
279 MODULE_DESCRIPTION("RTC class support");
280 MODULE_LICENSE("GPL");