/* * 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); } #ifdef CONFIG_RTC_HCTOSYS_DEVICE /* Result of the last RTC to system clock attempt. */ int rtc_hctosys_ret = -ENODEV; #endif #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; rtc_hctosys_ret = -ENODEV; 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); rtc_hctosys_ret = 0; 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");