class.c 8.6 KB
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/*
 * 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.
*/

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/kdev_t.h>
#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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#ifdef CONFIG_RTC_HCTOSYS_DEVICE
/* Result of the last RTC to system clock attempt. */
int rtc_hctosys_ret = -ENODEV;
#endif
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#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
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/*
 * On suspend(), measure the delta between one RTC and the
 * system's wall clock; restore it on resume().
 */

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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)
{
	struct rtc_device	*rtc = to_rtc_device(dev);
	struct rtc_time		tm;
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	struct timespec		delta, delta_delta;
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	if (has_persistent_clock())
		return 0;

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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);
	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);
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	if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {
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		/*
		 * 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);
	}
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	return 0;
}

static int rtc_resume(struct device *dev)
{
	struct rtc_device	*rtc = to_rtc_device(dev);
	struct rtc_time		tm;
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	struct timespec		new_system, new_rtc;
	struct timespec		sleep_time;
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	if (has_persistent_clock())
		return 0;

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	rtc_hctosys_ret = -ENODEV;
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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 */
	getnstimeofday(&new_system);
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	rtc_read_time(rtc, &tm);
	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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	rtc_tm_to_time(&tm, &new_rtc.tv_sec);
	new_rtc.tv_nsec = 0;

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	if (new_rtc.tv_sec < old_rtc.tv_sec) {
		pr_debug("%s:  time travel!\n", dev_name(&rtc->dev));
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		return 0;
	}

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	/* 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));
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	if (sleep_time.tv_sec >= 0)
		timekeeping_inject_sleeptime(&sleep_time);
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	rtc_hctosys_ret = 0;
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	return 0;
}

#else
#define rtc_suspend	NULL
#define rtc_resume	NULL
#endif


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/**
 * 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,
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					const struct rtc_class_ops *ops,
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					struct module *owner)
{
	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);
	if (id < 0) {
		err = id;
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		goto exit;
	}

	rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
	if (rtc == NULL) {
		err = -ENOMEM;
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		goto exit_ida;
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	}

	rtc->id = id;
	rtc->ops = ops;
	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;
	rtc->dev.class = rtc_class;
	rtc->dev.release = rtc_device_release;
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	mutex_init(&rtc->ops_lock);
	spin_lock_init(&rtc->irq_lock);
	spin_lock_init(&rtc->irq_task_lock);
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	init_waitqueue_head(&rtc->irq_queue);
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	/* Init timerqueue */
	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 */
	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	rtc->pie_timer.function = rtc_pie_update_irq;
	rtc->pie_enabled = 0;

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	/* 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))
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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) {
		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;

exit_kfree:
	kfree(rtc);

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exit_ida:
	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",
			name, err);
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	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)
{
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	if (get_device(&rtc->dev) != NULL) {
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		mutex_lock(&rtc->ops_lock);
		/* remove innards of this RTC, then disable it, before
		 * letting any rtc_class_open() users access it again
		 */
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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;
		mutex_unlock(&rtc->ops_lock);
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		put_device(&rtc->dev);
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	}
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}
EXPORT_SYMBOL_GPL(rtc_device_unregister);

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static void devm_rtc_device_release(struct device *dev, void *res)
{
	struct rtc_device *rtc = *(struct rtc_device **)res;

	rtc_device_unregister(rtc);
}

static int devm_rtc_device_match(struct device *dev, void *res, void *data)
{
	struct rtc **r = res;

	return *r == data;
}

/**
 * devm_rtc_device_register - resource managed rtc_device_register()
 * @name: the name of the device
 * @dev: the device to register
 * @ops: the rtc operations structure
 * @owner: the module owner
 *
 * @return a struct rtc on success, or an ERR_PTR on error
 *
 * Managed rtc_device_register(). The rtc_device returned from this function
 * are automatically freed on driver detach. See rtc_device_register()
 * for more information.
 */

struct rtc_device *devm_rtc_device_register(const char *name,
					struct device *dev,
					const struct rtc_class_ops *ops,
					struct module *owner)
{
	struct rtc_device **ptr, *rtc;

	ptr = devres_alloc(devm_rtc_device_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	rtc = rtc_device_register(name, dev, ops, owner);
	if (!IS_ERR(rtc)) {
		*ptr = rtc;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return rtc;
}
EXPORT_SYMBOL_GPL(devm_rtc_device_register);

/**
 * devm_rtc_device_unregister - resource managed devm_rtc_device_unregister()
 * @dev: the device to unregister
 * @rtc: the RTC class device to unregister
 *
 * Deallocated a rtc allocated with devm_rtc_device_register(). Normally this
 * function will not need to be called and the resource management code will
 * ensure that the resource is freed.
 */
void devm_rtc_device_unregister(struct device *dev, struct rtc_device *rtc)
{
	int rc;

	rc = devres_release(dev, devm_rtc_device_release,
				devm_rtc_device_match, rtc);
	WARN_ON(rc);
}
EXPORT_SYMBOL_GPL(devm_rtc_device_unregister);

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static int __init rtc_init(void)
{
	rtc_class = class_create(THIS_MODULE, "rtc");
	if (IS_ERR(rtc_class)) {
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		pr_err("couldn't create class\n");
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		return PTR_ERR(rtc_class);
	}
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	rtc_class->suspend = rtc_suspend;
	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;
}

static void __exit rtc_exit(void)
{
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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");
MODULE_LICENSE("GPL");