[linux.git] / drivers / rtc / class.c

// SPDX-License-Identifier: GPL-2.0
/*
 * RTC subsystem, base class
 *
 * Copyright (C) 2005 Tower Technologies
 * Author: Alessandro Zummo <[email protected]>
 *
 * 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);
	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_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. */
	rtc->set_offset_nsec =  NSEC_PER_SEC / 2;

	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 rtc_device_unregister(struct rtc_device *rtc)
{
	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);
	put_device(&rtc->dev);
}

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

	rtc_nvmem_unregister(rtc);

	if (rtc->registered)
		rtc_device_unregister(rtc);
	else
		put_device(&rtc->dev);
}

struct rtc_device *devm_rtc_allocate_device(struct device *dev)
{
	struct rtc_device **ptr, *rtc;
	int id, err;

	id = rtc_device_get_id(dev);
	if (id < 0)
		return ERR_PTR(id);

	ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
	if (!ptr) {
		err = -ENOMEM;
		goto exit_ida;
	}

	rtc = rtc_allocate_device();
	if (!rtc) {
		err = -ENOMEM;
		goto exit_devres;
	}

	*ptr = rtc;
	devres_add(dev, ptr);

	rtc->id = id;
	rtc->dev.parent = dev;
	dev_set_name(&rtc->dev, "rtc%d", id);

	return rtc;

exit_devres:
	devres_free(ptr);
exit_ida:
	ida_simple_remove(&rtc_ida, id);
	return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);

int __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);

	rtc->registered = true;
	dev_info(rtc->dev.parent, "registered as %s\n",
		 dev_name(&rtc->dev));

	return 0;
}
EXPORT_SYMBOL_GPL(__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 = __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);
Commit	Line	Data
cdf7545a	1	// SPDX-License-Identifier: GPL-2.0
0c86edc0 AZ	2	/*
	3	* RTC subsystem, base class
	4	*
	5	* Copyright (C) 2005 Tower Technologies
	6	* Author: Alessandro Zummo <[email protected]>
	7	*
	8	* class skeleton from drivers/hwmon/hwmon.c
cdf7545a	9	*/
0c86edc0	10
c100a5e0 JH	11	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
c100a5e0 JH	12
0c86edc0	13	#include <linux/module.h>
9d2b7e53	14	#include <linux/of.h>
0c86edc0 AZ	15	#include <linux/rtc.h>
	16	#include <linux/kdev_t.h>
	17	#include <linux/idr.h>
5a0e3ad6	18	#include <linux/slab.h>
6610e089	19	#include <linux/workqueue.h>
0c86edc0	20
5726fb20 DB	21	#include "rtc-core.h"
5726fb20 DB	22
6d03d06d	23	static DEFINE_IDA(rtc_ida);
0c86edc0 AZ	24	struct class *rtc_class;
0c86edc0 AZ	25
cd966209	26	static void rtc_device_release(struct device *dev)
0c86edc0	27	{
cd966209	28	struct rtc_device *rtc = to_rtc_device(dev);
606cc43c	29
6d03d06d	30	ida_simple_remove(&rtc_ida, rtc->id);
0c86edc0 AZ	31	kfree(rtc);
	32	}
	33
4c24e29e DF	34	#ifdef CONFIG_RTC_HCTOSYS_DEVICE
	35	/* Result of the last RTC to system clock attempt. */
	36	int rtc_hctosys_ret = -ENODEV;
	37	#endif
7ca1d488	38
92e7f04a	39	#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
7ca1d488 DB	40	/*
	41	* On suspend(), measure the delta between one RTC and the
	42	* system's wall clock; restore it on resume().
	43	*/
	44
d4bda8f8	45	static struct timespec64 old_rtc, old_system, old_delta;
3dcad5ff	46
92e7f04a	47	static int rtc_suspend(struct device *dev)
7ca1d488 DB	48	{
	49	struct rtc_device *rtc = to_rtc_device(dev);
	50	struct rtc_time tm;
d4bda8f8	51	struct timespec64 delta, delta_delta;
e1d60093	52	int err;
9ecf37eb	53
0fa88cb4	54	if (timekeeping_rtc_skipsuspend())
9ecf37eb FT	55	return 0;
9ecf37eb FT	56
d4afc76c	57	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
7ca1d488 DB	58	return 0;
7ca1d488 DB	59
3dcad5ff	60	/* snapshot the current RTC and system time at suspend*/
e1d60093 HG	61	err = rtc_read_time(rtc, &tm);
	62	if (err < 0) {
	63	pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));
	64	return 0;
	65	}
	66
5089ea15	67	ktime_get_real_ts64(&old_system);
d4bda8f8	68	old_rtc.tv_sec = rtc_tm_to_time64(&tm);
3dcad5ff	69
3dcad5ff JS	70	/*
	71	* To avoid drift caused by repeated suspend/resumes,
	72	* which each can add ~1 second drift error,
	73	* try to compensate so the difference in system time
	74	* and rtc time stays close to constant.
	75	*/
d4bda8f8 JS	76	delta = timespec64_sub(old_system, old_rtc);
d4bda8f8 JS	77	delta_delta = timespec64_sub(delta, old_delta);
6a8943d9	78	if (delta_delta.tv_sec < -2 \|\| delta_delta.tv_sec >= 2) {
3dcad5ff JS	79	/*
3dcad5ff JS	80	* if delta_delta is too large, assume time correction
606cc43c	81	* has occurred and set old_delta to the current delta.
3dcad5ff JS	82	*/
	83	old_delta = delta;
	84	} else {
	85	/* Otherwise try to adjust old_system to compensate */
d4bda8f8	86	old_system = timespec64_sub(old_system, delta_delta);
3dcad5ff	87	}
7ca1d488	88
7ca1d488 DB	89	return 0;
	90	}
	91
	92	static int rtc_resume(struct device *dev)
	93	{
	94	struct rtc_device *rtc = to_rtc_device(dev);
	95	struct rtc_time tm;
d4bda8f8 JS	96	struct timespec64 new_system, new_rtc;
d4bda8f8 JS	97	struct timespec64 sleep_time;
e1d60093	98	int err;
7ca1d488	99
0fa88cb4	100	if (timekeeping_rtc_skipresume())
9ecf37eb FT	101	return 0;
9ecf37eb FT	102
4c24e29e	103	rtc_hctosys_ret = -ENODEV;
d4afc76c	104	if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)
7ca1d488 DB	105	return 0;
7ca1d488 DB	106
3dcad5ff	107	/* snapshot the current rtc and system time at resume */
5089ea15	108	ktime_get_real_ts64(&new_system);
e1d60093 HG	109	err = rtc_read_time(rtc, &tm);
	110	if (err < 0) {
	111	pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));
	112	return 0;
	113	}
	114
d4bda8f8	115	new_rtc.tv_sec = rtc_tm_to_time64(&tm);
3dcad5ff JS	116	new_rtc.tv_nsec = 0;
3dcad5ff JS	117
6a8943d9 AH	118	if (new_rtc.tv_sec < old_rtc.tv_sec) {
6a8943d9 AH	119	pr_debug("%s: time travel!\n", dev_name(&rtc->dev));
7ca1d488 DB	120	return 0;
	121	}
	122
3dcad5ff	123	/* calculate the RTC time delta (sleep time)*/
d4bda8f8	124	sleep_time = timespec64_sub(new_rtc, old_rtc);
3dcad5ff JS	125
	126	/*
	127	* Since these RTC suspend/resume handlers are not called
	128	* at the very end of suspend or the start of resume,
	129	* some run-time may pass on either sides of the sleep time
	130	* so subtract kernel run-time between rtc_suspend to rtc_resume
	131	* to keep things accurate.
	132	*/
d4bda8f8	133	sleep_time = timespec64_sub(sleep_time,
606cc43c	134	timespec64_sub(new_system, old_system));
7ca1d488	135
6a8943d9	136	if (sleep_time.tv_sec >= 0)
d4bda8f8	137	timekeeping_inject_sleeptime64(&sleep_time);
4c24e29e	138	rtc_hctosys_ret = 0;
7ca1d488 DB	139	return 0;
	140	}
	141
92e7f04a SK	142	static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);
92e7f04a SK	143	#define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops)
7ca1d488	144	#else
92e7f04a	145	#define RTC_CLASS_DEV_PM_OPS NULL
7ca1d488 DB	146	#endif
7ca1d488 DB	147
3068a254	148	/* Ensure the caller will set the id before releasing the device */
d1bec20f AB	149	static struct rtc_device *rtc_allocate_device(void)
	150	{
	151	struct rtc_device *rtc;
	152
	153	rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);
	154	if (!rtc)
	155	return NULL;
	156
	157	device_initialize(&rtc->dev);
	158
0f295b06 JG	159	/* Drivers can revise this default after allocating the device. */
	160	rtc->set_offset_nsec = NSEC_PER_SEC / 2;
	161
d1bec20f AB	162	rtc->irq_freq = 1;
	163	rtc->max_user_freq = 64;
	164	rtc->dev.class = rtc_class;
	165	rtc->dev.groups = rtc_get_dev_attribute_groups();
	166	rtc->dev.release = rtc_device_release;
	167
	168	mutex_init(&rtc->ops_lock);
	169	spin_lock_init(&rtc->irq_lock);
d1bec20f AB	170	init_waitqueue_head(&rtc->irq_queue);
	171
	172	/* Init timerqueue */
	173	timerqueue_init_head(&rtc->timerqueue);
	174	INIT_WORK(&rtc->irqwork, rtc_timer_do_work);
	175	/* Init aie timer */
9a032011	176	rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc);
d1bec20f	177	/* Init uie timer */
9a032011	178	rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc);
d1bec20f AB	179	/* Init pie timer */
	180	hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	181	rtc->pie_timer.function = rtc_pie_update_irq;
	182	rtc->pie_enabled = 0;
	183
	184	return rtc;
	185	}
7ca1d488	186
b91336df AB	187	static int rtc_device_get_id(struct device *dev)
	188	{
	189	int of_id = -1, id = -1;
	190
	191	if (dev->of_node)
	192	of_id = of_alias_get_id(dev->of_node, "rtc");
	193	else if (dev->parent && dev->parent->of_node)
	194	of_id = of_alias_get_id(dev->parent->of_node, "rtc");
	195
	196	if (of_id >= 0) {
	197	id = ida_simple_get(&rtc_ida, of_id, of_id + 1, GFP_KERNEL);
	198	if (id < 0)
	199	dev_warn(dev, "/aliases ID %d not available\n", of_id);
	200	}
	201
	202	if (id < 0)
	203	id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
	204
	205	return id;
	206	}
	207
98951564 BW	208	static void rtc_device_get_offset(struct rtc_device *rtc)
	209	{
	210	time64_t range_secs;
	211	u32 start_year;
	212	int ret;
	213
	214	/*
	215	* If RTC driver did not implement the range of RTC hardware device,
	216	* then we can not expand the RTC range by adding or subtracting one
	217	* offset.
	218	*/
	219	if (rtc->range_min == rtc->range_max)
	220	return;
	221
	222	ret = device_property_read_u32(rtc->dev.parent, "start-year",
	223	&start_year);
	224	if (!ret) {
	225	rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);
	226	rtc->set_start_time = true;
	227	}
	228
	229	/*
	230	* If user did not implement the start time for RTC driver, then no
	231	* need to expand the RTC range.
	232	*/
	233	if (!rtc->set_start_time)
	234	return;
	235
	236	range_secs = rtc->range_max - rtc->range_min + 1;
	237
	238	/*
	239	* If the start_secs is larger than the maximum seconds (rtc->range_max)
	240	* supported by RTC hardware or the maximum seconds of new expanded
	241	* range (start_secs + rtc->range_max - rtc->range_min) is less than
	242	* rtc->range_min, which means the minimum seconds (rtc->range_min) of
	243	* RTC hardware will be mapped to start_secs by adding one offset, so
	244	* the offset seconds calculation formula should be:
	245	* rtc->offset_secs = rtc->start_secs - rtc->range_min;
	246	*
	247	* If the start_secs is larger than the minimum seconds (rtc->range_min)
	248	* supported by RTC hardware, then there is one region is overlapped
	249	* between the original RTC hardware range and the new expanded range,
	250	* and this overlapped region do not need to be mapped into the new
	251	* expanded range due to it is valid for RTC device. So the minimum
	252	* seconds of RTC hardware (rtc->range_min) should be mapped to
	253	* rtc->range_max + 1, then the offset seconds formula should be:
	254	* rtc->offset_secs = rtc->range_max - rtc->range_min + 1;
	255	*
	256	* If the start_secs is less than the minimum seconds (rtc->range_min),
	257	* which is similar to case 2. So the start_secs should be mapped to
	258	* start_secs + rtc->range_max - rtc->range_min + 1, then the
	259	* offset seconds formula should be:
	260	* rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);
	261	*
	262	* Otherwise the offset seconds should be 0.
	263	*/
	264	if (rtc->start_secs > rtc->range_max \|\|
	265	rtc->start_secs + range_secs - 1 < rtc->range_min)
	266	rtc->offset_secs = rtc->start_secs - rtc->range_min;
	267	else if (rtc->start_secs > rtc->range_min)
	268	rtc->offset_secs = range_secs;
	269	else if (rtc->start_secs < rtc->range_min)
	270	rtc->offset_secs = -range_secs;
	271	else
272	rtc->offset_secs = 0;
273	}
274
0c86edc0 AZ	275	/**
	276	* rtc_device_unregister - removes the previously registered RTC class device
	277	*
	278	* @rtc: the RTC class device to destroy
	279	*/
1e479c61	280	static void rtc_device_unregister(struct rtc_device *rtc)
0c86edc0	281	{
c3b399a4 DT	282	mutex_lock(&rtc->ops_lock);
	283	/*
	284	* Remove innards of this RTC, then disable it, before
	285	* letting any rtc_class_open() users access it again
	286	*/
c3b399a4	287	rtc_proc_del_device(rtc);
d5ed9177	288	cdev_device_del(&rtc->char_dev, &rtc->dev);
c3b399a4 DT	289	rtc->ops = NULL;
	290	mutex_unlock(&rtc->ops_lock);
	291	put_device(&rtc->dev);
0c86edc0	292	}
0c86edc0	293
3068a254 AB	294	static void devm_rtc_release_device(struct device dev, void res)
	295	{
	296	struct rtc_device rtc = (struct rtc_device **)res;
	297
ac75779b AB	298	rtc_nvmem_unregister(rtc);
ac75779b AB	299
3068a254 AB	300	if (rtc->registered)
	301	rtc_device_unregister(rtc);
	302	else
	303	put_device(&rtc->dev);
	304	}
	305
	306	struct rtc_device devm_rtc_allocate_device(struct device dev)
	307	{
	308	struct rtc_device *ptr, rtc;
	309	int id, err;
	310
	311	id = rtc_device_get_id(dev);
	312	if (id < 0)
	313	return ERR_PTR(id);
	314
	315	ptr = devres_alloc(devm_rtc_release_device, sizeof(*ptr), GFP_KERNEL);
	316	if (!ptr) {
	317	err = -ENOMEM;
	318	goto exit_ida;
	319	}
	320
	321	rtc = rtc_allocate_device();
	322	if (!rtc) {
	323	err = -ENOMEM;
	324	goto exit_devres;
	325	}
	326
	327	*ptr = rtc;
	328	devres_add(dev, ptr);
	329
	330	rtc->id = id;
	331	rtc->dev.parent = dev;
	332	dev_set_name(&rtc->dev, "rtc%d", id);
	333
	334	return rtc;
	335
	336	exit_devres:
	337	devres_free(ptr);
	338	exit_ida:
	339	ida_simple_remove(&rtc_ida, id);
	340	return ERR_PTR(err);
	341	}
	342	EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);
	343
	344	int __rtc_register_device(struct module owner, struct rtc_device rtc)
	345	{
	346	struct rtc_wkalrm alrm;
	347	int err;
	348
924068e5 AB	349	if (!rtc->ops) {
924068e5 AB	350	dev_dbg(&rtc->dev, "no ops set\n");
3068a254	351	return -EINVAL;
924068e5	352	}
3068a254 AB	353
3068a254 AB	354	rtc->owner = owner;
98951564	355	rtc_device_get_offset(rtc);
3068a254 AB	356
	357	/* Check to see if there is an ALARM already set in hw */
	358	err = __rtc_read_alarm(rtc, &alrm);
	359	if (!err && !rtc_valid_tm(&alrm.time))
	360	rtc_initialize_alarm(rtc, &alrm);
	361
	362	rtc_dev_prepare(rtc);
	363
	364	err = cdev_device_add(&rtc->char_dev, &rtc->dev);
	365	if (err)
	366	dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",
	367	MAJOR(rtc->dev.devt), rtc->id);
	368	else
	369	dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",
	370	MAJOR(rtc->dev.devt), rtc->id);
	371
	372	rtc_proc_add_device(rtc);
	373
	374	rtc->registered = true;
	375	dev_info(rtc->dev.parent, "registered as %s\n",
	376	dev_name(&rtc->dev));
	377
	378	return 0;
	379	}
	380	EXPORT_SYMBOL_GPL(__rtc_register_device);
	381
a2694414 AB	382	/**
	383	* devm_rtc_device_register - resource managed rtc_device_register()
	384	* @dev: the device to register
	385	* @name: the name of the device (unused)
	386	* @ops: the rtc operations structure
	387	* @owner: the module owner
	388	*
	389	* @return a struct rtc on success, or an ERR_PTR on error
	390	*
	391	* Managed rtc_device_register(). The rtc_device returned from this function
	392	* are automatically freed on driver detach.
	393	* This function is deprecated, use devm_rtc_allocate_device and
	394	* rtc_register_device instead
	395	*/
	396	struct rtc_device devm_rtc_device_register(struct device dev,
606cc43c AB	397	const char *name,
	398	const struct rtc_class_ops *ops,
	399	struct module *owner)
a2694414 AB	400	{
	401	struct rtc_device *rtc;
	402	int err;
	403
	404	rtc = devm_rtc_allocate_device(dev);
	405	if (IS_ERR(rtc))
	406	return rtc;
	407
	408	rtc->ops = ops;
	409
	410	err = __rtc_register_device(owner, rtc);
	411	if (err)
	412	return ERR_PTR(err);
	413
	414	return rtc;
	415	}
	416	EXPORT_SYMBOL_GPL(devm_rtc_device_register);
	417
0c86edc0 AZ	418	static int __init rtc_init(void)
	419	{
	420	rtc_class = class_create(THIS_MODULE, "rtc");
	421	if (IS_ERR(rtc_class)) {
c100a5e0	422	pr_err("couldn't create class\n");
0c86edc0 AZ	423	return PTR_ERR(rtc_class);
0c86edc0 AZ	424	}
92e7f04a	425	rtc_class->pm = RTC_CLASS_DEV_PM_OPS;
5726fb20	426	rtc_dev_init();
0c86edc0 AZ	427	return 0;
0c86edc0 AZ	428	}
818a8674	429	subsys_initcall(rtc_init);