![Jonathan Cameron](/assets/img/avatar_default.png)
This is the one use of an ida that doesn't retry on receiving -EAGAIN. I'm assuming do so will cause no harm and may help on a rare occasion. Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
274 lines
6.6 KiB
C
274 lines
6.6 KiB
C
/*
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* RTC subsystem, base class
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*
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* Copyright (C) 2005 Tower Technologies
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* Author: Alessandro Zummo <a.zummo@towertech.it>
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*
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* class skeleton from drivers/hwmon/hwmon.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/rtc.h>
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#include <linux/kdev_t.h>
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#include <linux/idr.h>
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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#include "rtc-core.h"
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static DEFINE_IDA(rtc_ida);
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struct class *rtc_class;
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static void rtc_device_release(struct device *dev)
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{
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struct rtc_device *rtc = to_rtc_device(dev);
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ida_simple_remove(&rtc_ida, rtc->id);
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kfree(rtc);
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}
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#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
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/*
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* On suspend(), measure the delta between one RTC and the
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* system's wall clock; restore it on resume().
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*/
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static struct timespec old_rtc, old_system, old_delta;
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static int rtc_suspend(struct device *dev, pm_message_t mesg)
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{
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struct rtc_device *rtc = to_rtc_device(dev);
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struct rtc_time tm;
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struct timespec delta, delta_delta;
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if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
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return 0;
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/* snapshot the current RTC and system time at suspend*/
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rtc_read_time(rtc, &tm);
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getnstimeofday(&old_system);
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rtc_tm_to_time(&tm, &old_rtc.tv_sec);
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/*
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* To avoid drift caused by repeated suspend/resumes,
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* which each can add ~1 second drift error,
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* try to compensate so the difference in system time
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* and rtc time stays close to constant.
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*/
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delta = timespec_sub(old_system, old_rtc);
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delta_delta = timespec_sub(delta, old_delta);
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if (abs(delta_delta.tv_sec) >= 2) {
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/*
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* if delta_delta is too large, assume time correction
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* has occured and set old_delta to the current delta.
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*/
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old_delta = delta;
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} else {
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/* Otherwise try to adjust old_system to compensate */
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old_system = timespec_sub(old_system, delta_delta);
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}
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return 0;
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}
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static int rtc_resume(struct device *dev)
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{
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struct rtc_device *rtc = to_rtc_device(dev);
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struct rtc_time tm;
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struct timespec new_system, new_rtc;
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struct timespec sleep_time;
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if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
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return 0;
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/* snapshot the current rtc and system time at resume */
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getnstimeofday(&new_system);
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rtc_read_time(rtc, &tm);
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if (rtc_valid_tm(&tm) != 0) {
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pr_debug("%s: bogus resume time\n", dev_name(&rtc->dev));
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return 0;
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}
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rtc_tm_to_time(&tm, &new_rtc.tv_sec);
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new_rtc.tv_nsec = 0;
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if (new_rtc.tv_sec <= old_rtc.tv_sec) {
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if (new_rtc.tv_sec < old_rtc.tv_sec)
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pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
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return 0;
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}
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/* calculate the RTC time delta (sleep time)*/
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sleep_time = timespec_sub(new_rtc, old_rtc);
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/*
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* Since these RTC suspend/resume handlers are not called
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* at the very end of suspend or the start of resume,
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* some run-time may pass on either sides of the sleep time
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* so subtract kernel run-time between rtc_suspend to rtc_resume
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* to keep things accurate.
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*/
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sleep_time = timespec_sub(sleep_time,
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timespec_sub(new_system, old_system));
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timekeeping_inject_sleeptime(&sleep_time);
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return 0;
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}
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#else
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#define rtc_suspend NULL
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#define rtc_resume NULL
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#endif
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/**
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* rtc_device_register - register w/ RTC class
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* @dev: the device to register
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*
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* rtc_device_unregister() must be called when the class device is no
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* longer needed.
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*
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* Returns the pointer to the new struct class device.
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*/
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struct rtc_device *rtc_device_register(const char *name, struct device *dev,
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const struct rtc_class_ops *ops,
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struct module *owner)
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{
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struct rtc_device *rtc;
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struct rtc_wkalrm alrm;
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int id, err;
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id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
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if (id < 0) {
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err = id;
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goto exit;
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}
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rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
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if (rtc == NULL) {
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err = -ENOMEM;
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goto exit_ida;
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}
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rtc->id = id;
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rtc->ops = ops;
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rtc->owner = owner;
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rtc->irq_freq = 1;
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rtc->max_user_freq = 64;
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rtc->dev.parent = dev;
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rtc->dev.class = rtc_class;
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rtc->dev.release = rtc_device_release;
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mutex_init(&rtc->ops_lock);
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spin_lock_init(&rtc->irq_lock);
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spin_lock_init(&rtc->irq_task_lock);
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init_waitqueue_head(&rtc->irq_queue);
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/* Init timerqueue */
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timerqueue_init_head(&rtc->timerqueue);
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INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
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/* Init aie timer */
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rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, (void *)rtc);
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/* Init uie timer */
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rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, (void *)rtc);
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/* Init pie timer */
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hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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rtc->pie_timer.function = rtc_pie_update_irq;
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rtc->pie_enabled = 0;
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/* Check to see if there is an ALARM already set in hw */
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err = __rtc_read_alarm(rtc, &alrm);
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if (!err && !rtc_valid_tm(&alrm.time))
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rtc_initialize_alarm(rtc, &alrm);
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strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
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dev_set_name(&rtc->dev, "rtc%d", id);
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rtc_dev_prepare(rtc);
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err = device_register(&rtc->dev);
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if (err) {
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put_device(&rtc->dev);
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goto exit_kfree;
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}
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rtc_dev_add_device(rtc);
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rtc_sysfs_add_device(rtc);
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rtc_proc_add_device(rtc);
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dev_info(dev, "rtc core: registered %s as %s\n",
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rtc->name, dev_name(&rtc->dev));
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return rtc;
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exit_kfree:
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kfree(rtc);
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exit_ida:
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ida_simple_remove(&rtc_ida, id);
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exit:
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dev_err(dev, "rtc core: unable to register %s, err = %d\n",
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name, err);
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return ERR_PTR(err);
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}
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EXPORT_SYMBOL_GPL(rtc_device_register);
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/**
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* rtc_device_unregister - removes the previously registered RTC class device
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*
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* @rtc: the RTC class device to destroy
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*/
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void rtc_device_unregister(struct rtc_device *rtc)
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{
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if (get_device(&rtc->dev) != NULL) {
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mutex_lock(&rtc->ops_lock);
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/* remove innards of this RTC, then disable it, before
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* letting any rtc_class_open() users access it again
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*/
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rtc_sysfs_del_device(rtc);
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rtc_dev_del_device(rtc);
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rtc_proc_del_device(rtc);
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device_unregister(&rtc->dev);
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rtc->ops = NULL;
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mutex_unlock(&rtc->ops_lock);
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put_device(&rtc->dev);
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}
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}
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EXPORT_SYMBOL_GPL(rtc_device_unregister);
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static int __init rtc_init(void)
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{
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rtc_class = class_create(THIS_MODULE, "rtc");
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if (IS_ERR(rtc_class)) {
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printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
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return PTR_ERR(rtc_class);
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}
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rtc_class->suspend = rtc_suspend;
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rtc_class->resume = rtc_resume;
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rtc_dev_init();
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rtc_sysfs_init(rtc_class);
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return 0;
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}
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static void __exit rtc_exit(void)
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{
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rtc_dev_exit();
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class_destroy(rtc_class);
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ida_destroy(&rtc_ida);
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}
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subsys_initcall(rtc_init);
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module_exit(rtc_exit);
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MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
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MODULE_DESCRIPTION("RTC class support");
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MODULE_LICENSE("GPL");
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