/* * RTC subsystem, base class * * Copyright (C) 2005 Tower Technologies * Author: Alessandro Zummo <a.zummo@towertech.it> * * class skeleton from drivers/hwmon/hwmon.c * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation.*/ #include <linux/module.h>#include <linux/rtc.h>#include <linux/kdev_t.h>#include <linux/idr.h>#include <linux/slab.h>#include <linux/workqueue.h> #include "rtc-core.h"  static DEFINE_IDA(rtc_ida);struct class *rtc_class; static void rtc_device_release(struct device *dev){	struct rtc_device *rtc = to_rtc_device(dev);	ida_simple_remove(&rtc_ida, rtc->id);	kfree(rtc);} #if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE) /* * On suspend(), measure the delta between one RTC and the * system's wall clock; restore it on resume(). */ static struct timespec old_rtc, old_system, old_delta;  static int rtc_suspend(struct device *dev, pm_message_t mesg){	struct rtc_device	*rtc = to_rtc_device(dev);	struct rtc_time		tm;	struct timespec		delta, delta_delta;	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)		return 0; 	/* snapshot the current RTC and system time at suspend*/	rtc_read_time(rtc, &tm);	getnstimeofday(&old_system);	rtc_tm_to_time(&tm, &old_rtc.tv_sec);  	/*	 * To avoid drift caused by repeated suspend/resumes,	 * which each can add ~1 second drift error,	 * try to compensate so the difference in system time	 * and rtc time stays close to constant.	 */	delta = timespec_sub(old_system, old_rtc);	delta_delta = timespec_sub(delta, old_delta);	if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {		/*		 * if delta_delta is too large, assume time correction		 * has occured and set old_delta to the current delta.		 */		old_delta = delta;	} else {		/* Otherwise try to adjust old_system to compensate */		old_system = timespec_sub(old_system, delta_delta);	} 	return 0;} static int rtc_resume(struct device *dev){	struct rtc_device	*rtc = to_rtc_device(dev);	struct rtc_time		tm;	struct timespec		new_system, new_rtc;	struct timespec		sleep_time; 	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)		return 0; 	/* snapshot the current rtc and system time at resume */	getnstimeofday(&new_system);	rtc_read_time(rtc, &tm);	if (rtc_valid_tm(&tm) != 0) {		pr_debug("%s:  bogus resume time\n", dev_name(&rtc->dev));		return 0;	}	rtc_tm_to_time(&tm, &new_rtc.tv_sec);	new_rtc.tv_nsec = 0; 	if (new_rtc.tv_sec < old_rtc.tv_sec) {		pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));		return 0;	} 	/* calculate the RTC time delta (sleep time)*/	sleep_time = timespec_sub(new_rtc, old_rtc); 	/*	 * Since these RTC suspend/resume handlers are not called	 * at the very end of suspend or the start of resume,	 * some run-time may pass on either sides of the sleep time	 * so subtract kernel run-time between rtc_suspend to rtc_resume	 * to keep things accurate.	 */	sleep_time = timespec_sub(sleep_time,			timespec_sub(new_system, old_system)); 	if (sleep_time.tv_sec >= 0)		timekeeping_inject_sleeptime(&sleep_time);	return 0;} #else#define rtc_suspend	NULL#define rtc_resume	NULL#endif  /** * rtc_device_register - register w/ RTC class * @dev: the device to register * * rtc_device_unregister() must be called when the class device is no * longer needed. * * Returns the pointer to the new struct class device. */struct rtc_device *rtc_device_register(const char *name, struct device *dev,					const struct rtc_class_ops *ops,					struct module *owner){	struct rtc_device *rtc;	struct rtc_wkalrm alrm;	int id, err; 	id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);	if (id < 0) {		err = id;		goto exit;	} 	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);	if (rtc == NULL) {		err = -ENOMEM;		goto exit_ida;	} 	rtc->id = id;	rtc->ops = ops;	rtc->owner = owner;	rtc->irq_freq = 1;	rtc->max_user_freq = 64;	rtc->dev.parent = dev;	rtc->dev.class = rtc_class;	rtc->dev.release = rtc_device_release; 	mutex_init(&rtc->ops_lock);	spin_lock_init(&rtc->irq_lock);	spin_lock_init(&rtc->irq_task_lock);	init_waitqueue_head(&rtc->irq_queue); 	/* Init timerqueue */	timerqueue_init_head(&rtc->timerqueue);	INIT_WORK(&rtc->irqwork, rtc_timer_do_work);	/* Init aie timer */	rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);	/* Init uie timer */	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);	/* Init pie timer */	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);	rtc->pie_timer.function = rtc_pie_update_irq;	rtc->pie_enabled = 0; 	/* Check to see if there is an ALARM already set in hw */	err = __rtc_read_alarm(rtc, &alrm); 	if (!err && !rtc_valid_tm(&alrm.time))		rtc_initialize_alarm(rtc, &alrm); 	strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);	dev_set_name(&rtc->dev, "rtc%d", id); 	rtc_dev_prepare(rtc); 	err = device_register(&rtc->dev);	if (err) {		put_device(&rtc->dev);		goto exit_kfree;	} 	rtc_dev_add_device(rtc);	rtc_sysfs_add_device(rtc);	rtc_proc_add_device(rtc); 	dev_info(dev, "rtc core: registered %s as %s\n",			rtc->name, dev_name(&rtc->dev)); 	return rtc; exit_kfree:	kfree(rtc); exit_ida:	ida_simple_remove(&rtc_ida, id); exit:	dev_err(dev, "rtc core: unable to register %s, err = %d\n",			name, err);	return ERR_PTR(err);}EXPORT_SYMBOL_GPL(rtc_device_register);  /** * rtc_device_unregister - removes the previously registered RTC class device * * @rtc: the RTC class device to destroy */void rtc_device_unregister(struct rtc_device *rtc){	if (get_device(&rtc->dev) != NULL) {		mutex_lock(&rtc->ops_lock);		/* remove innards of this RTC, then disable it, before		 * letting any rtc_class_open() users access it again		 */		rtc_sysfs_del_device(rtc);		rtc_dev_del_device(rtc);		rtc_proc_del_device(rtc);		device_unregister(&rtc->dev);		rtc->ops = NULL;		mutex_unlock(&rtc->ops_lock);		put_device(&rtc->dev);	}}EXPORT_SYMBOL_GPL(rtc_device_unregister); static int __init rtc_init(void){	rtc_class = class_create(THIS_MODULE, "rtc");	if (IS_ERR(rtc_class)) {		printk(KERN_ERR "%s: couldn't create class\n", __FILE__);		return PTR_ERR(rtc_class);	}	rtc_class->suspend = rtc_suspend;	rtc_class->resume = rtc_resume;	rtc_dev_init();	rtc_sysfs_init(rtc_class);	return 0;} static void __exit rtc_exit(void){	rtc_dev_exit();	class_destroy(rtc_class);	ida_destroy(&rtc_ida);} subsys_initcall(rtc_init);module_exit(rtc_exit); MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");MODULE_DESCRIPTION("RTC class support");MODULE_LICENSE("GPL");