// SPDX-License-Identifier: GPL-2.0/* * RTC subsystem, base class * * Copyright (C) 2005 Tower Technologies * Author: Alessandro Zummo <a.zummo@towertech.it> * * class skeleton from drivers/hwmon/hwmon.c */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h>#include <linux/of.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);	mutex_destroy(&rtc->ops_lock);	kfree(rtc);} #ifdef CONFIG_RTC_HCTOSYS_DEVICE/* Result of the last RTC to system clock attempt. */int rtc_hctosys_ret = -ENODEV; /* IMPORTANT: the RTC only stores whole seconds. It is arbitrary * whether it stores the most close value or the value with partial * seconds truncated. However, it is important that we use it to store * the truncated value. This is because otherwise it is necessary, * in an rtc sync function, to read both xtime.tv_sec and * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read * of >32bits is not possible. So storing the most close value would * slow down the sync API. So here we have the truncated value and * the best guess is to add 0.5s. */ static void rtc_hctosys(struct rtc_device *rtc){	int err;	struct rtc_time tm;	struct timespec64 tv64 = {		.tv_nsec = NSEC_PER_SEC >> 1,	}; 	err = rtc_read_time(rtc, &tm);	if (err) {		dev_err(rtc->dev.parent,			"hctosys: unable to read the hardware clock\n");		goto err_read;	} 	tv64.tv_sec = rtc_tm_to_time64(&tm); #if BITS_PER_LONG == 32	if (tv64.tv_sec > INT_MAX) {		err = -ERANGE;		goto err_read;	}#endif 	err = do_settimeofday64(&tv64); 	dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n",		 &tm, (long long)tv64.tv_sec); err_read:	rtc_hctosys_ret = err;}#endif #if defined(CONFIG_PM_SLEEP) && 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 timespec64 old_rtc, old_system, old_delta; static int rtc_suspend(struct device *dev){	struct rtc_device	*rtc = to_rtc_device(dev);	struct rtc_time		tm;	struct timespec64	delta, delta_delta;	int err; 	if (timekeeping_rtc_skipsuspend())		return 0; 	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)		return 0; 	/* snapshot the current RTC and system time at suspend*/	err = rtc_read_time(rtc, &tm);	if (err < 0) {		pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));		return 0;	} 	ktime_get_real_ts64(&old_system);	old_rtc.tv_sec = rtc_tm_to_time64(&tm); 	/*	 * 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 = timespec64_sub(old_system, old_rtc);	delta_delta = timespec64_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 occurred and set old_delta to the current delta.		 */		old_delta = delta;	} else {		/* Otherwise try to adjust old_system to compensate */		old_system = timespec64_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 timespec64	new_system, new_rtc;	struct timespec64	sleep_time;	int err; 	if (timekeeping_rtc_skipresume())		return 0; 	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 */	ktime_get_real_ts64(&new_system);	err = rtc_read_time(rtc, &tm);	if (err < 0) {		pr_debug("%s:  fail to read rtc time\n", dev_name(&rtc->dev));		return 0;	} 	new_rtc.tv_sec = rtc_tm_to_time64(&tm);	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 = timespec64_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 = timespec64_sub(sleep_time,				    timespec64_sub(new_system, old_system)); 	if (sleep_time.tv_sec >= 0)		timekeeping_inject_sleeptime64(&sleep_time);	rtc_hctosys_ret = 0;	return 0;} static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);#define RTC_CLASS_DEV_PM_OPS	(&rtc_class_dev_pm_ops)#else#define RTC_CLASS_DEV_PM_OPS	NULL#endif /* Ensure the caller will set the id before releasing the device */static struct rtc_device *rtc_allocate_device(void){	struct rtc_device *rtc; 	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);	if (!rtc)		return NULL; 	device_initialize(&rtc->dev); 	/*	 * Drivers can revise this default after allocating the device.	 * The default is what most RTCs do: Increment seconds exactly one	 * second after the write happened. This adds a default transport	 * time of 5ms which is at least halfways close to reality.	 */	rtc->set_offset_nsec = NSEC_PER_SEC + 5 * NSEC_PER_MSEC; 	rtc->irq_freq = 1;	rtc->max_user_freq = 64;	rtc->dev.class = rtc_class;	rtc->dev.groups = rtc_get_dev_attribute_groups();	rtc->dev.release = rtc_device_release; 	mutex_init(&rtc->ops_lock);	spin_lock_init(&rtc->irq_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, rtc);	/* Init uie timer */	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, 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; 	return rtc;} static int rtc_device_get_id(struct device *dev){	int of_id = -1, id = -1; 	if (dev->of_node)		of_id = of_alias_get_id(dev->of_node, "rtc");	else if (dev->parent && dev->parent->of_node)		of_id = of_alias_get_id(dev->parent->of_node, "rtc"); 	if (of_id >= 0) {		id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);		if (id < 0)			dev_warn(dev, "/aliases ID %d not available\n", of_id);	} 	if (id < 0)		id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL); 	return id;} static void rtc_device_get_offset(struct rtc_device *rtc){	time64_t range_secs;	u32 start_year;	int ret; 	/*	 * If RTC driver did not implement the range of RTC hardware device,	 * then we can not expand the RTC range by adding or subtracting one	 * offset.	 */	if (rtc->range_min == rtc->range_max)		return; 	ret = device_property_read_u32(rtc->dev.parent, "start-year",				       &start_year);	if (!ret) {		rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);		rtc->set_start_time = true;	} 	/*	 * If user did not implement the start time for RTC driver, then no	 * need to expand the RTC range.	 */	if (!rtc->set_start_time)		return; 	range_secs = rtc->range_max - rtc->range_min + 1; 	/*	 * If the start_secs is larger than the maximum seconds (rtc->range_max)	 * supported by RTC hardware or the maximum seconds of new expanded	 * range (start_secs + rtc->range_max - rtc->range_min) is less than	 * rtc->range_min, which means the minimum seconds (rtc->range_min) of	 * RTC hardware will be mapped to start_secs by adding one offset, so	 * the offset seconds calculation formula should be:	 * rtc->offset_secs = rtc->start_secs - rtc->range_min;	 *	 * If the start_secs is larger than the minimum seconds (rtc->range_min)	 * supported by RTC hardware, then there is one region is overlapped	 * between the original RTC hardware range and the new expanded range,	 * and this overlapped region do not need to be mapped into the new	 * expanded range due to it is valid for RTC device. So the minimum	 * seconds of RTC hardware (rtc->range_min) should be mapped to	 * rtc->range_max + 1, then the offset seconds formula should be:	 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;	 *	 * If the start_secs is less than the minimum seconds (rtc->range_min),	 * which is similar to case 2. So the start_secs should be mapped to	 * start_secs + rtc->range_max - rtc->range_min + 1, then the	 * offset seconds formula should be:	 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);	 *	 * Otherwise the offset seconds should be 0.	 */	if (rtc->start_secs > rtc->range_max ||	    rtc->start_secs + range_secs - 1 < rtc->range_min)		rtc->offset_secs = rtc->start_secs - rtc->range_min;	else if (rtc->start_secs > rtc->range_min)		rtc->offset_secs = range_secs;	else if (rtc->start_secs < rtc->range_min)		rtc->offset_secs = -range_secs;	else		rtc->offset_secs = 0;} /** * rtc_device_unregister - removes the previously registered RTC class device * * @rtc: the RTC class device to destroy */static void devm_rtc_unregister_device(void *data){	struct rtc_device *rtc = data; 	mutex_lock(&rtc->ops_lock);	/*	 * Remove innards of this RTC, then disable it, before	 * letting any rtc_class_open() users access it again	 */	rtc_proc_del_device(rtc);	cdev_device_del(&rtc->char_dev, &rtc->dev);	rtc->ops = NULL;	mutex_unlock(&rtc->ops_lock);} static void devm_rtc_release_device(void *res){	struct rtc_device *rtc = res; 	put_device(&rtc->dev);} struct rtc_device *devm_rtc_allocate_device(struct device *dev){	struct rtc_device *rtc;	int id, err; 	id = rtc_device_get_id(dev);	if (id < 0)		return ERR_PTR(id); 	rtc = rtc_allocate_device();	if (!rtc) {		ida_simple_remove(&rtc_ida, id);		return ERR_PTR(-ENOMEM);	} 	rtc->id = id;	rtc->dev.parent = dev;	dev_set_name(&rtc->dev, "rtc%d", id); 	err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);	if (err)		return ERR_PTR(err); 	return rtc;}EXPORT_SYMBOL_GPL(devm_rtc_allocate_device); int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc){	struct rtc_wkalrm alrm;	int err; 	if (!rtc->ops) {		dev_dbg(&rtc->dev, "no ops set\n");		return -EINVAL;	} 	rtc->owner = owner;	rtc_device_get_offset(rtc); 	/* 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); 	rtc_dev_prepare(rtc); 	err = cdev_device_add(&rtc->char_dev, &rtc->dev);	if (err)		dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",			 MAJOR(rtc->dev.devt), rtc->id);	else		dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",			MAJOR(rtc->dev.devt), rtc->id); 	rtc_proc_add_device(rtc); 	dev_info(rtc->dev.parent, "registered as %s\n",		 dev_name(&rtc->dev)); #ifdef CONFIG_RTC_HCTOSYS_DEVICE	if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE))		rtc_hctosys(rtc);#endif 	return devm_add_action_or_reset(rtc->dev.parent,					devm_rtc_unregister_device, rtc);}EXPORT_SYMBOL_GPL(__devm_rtc_register_device); /** * devm_rtc_device_register - resource managed rtc_device_register() * @dev: the device to register * @name: the name of the device (unused) * @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. * This function is deprecated, use devm_rtc_allocate_device and * rtc_register_device instead */struct rtc_device *devm_rtc_device_register(struct device *dev,					    const char *name,					    const struct rtc_class_ops *ops,					    struct module *owner){	struct rtc_device *rtc;	int err; 	rtc = devm_rtc_allocate_device(dev);	if (IS_ERR(rtc))		return rtc; 	rtc->ops = ops; 	err = __devm_rtc_register_device(owner, rtc);	if (err)		return ERR_PTR(err); 	return rtc;}EXPORT_SYMBOL_GPL(devm_rtc_device_register); static int __init rtc_init(void){	rtc_class = class_create(THIS_MODULE, "rtc");	if (IS_ERR(rtc_class)) {		pr_err("couldn't create class\n");		return PTR_ERR(rtc_class);	}	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;	rtc_dev_init();	return 0;}subsys_initcall(rtc_init);