// 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);
static void rtc_device_release(struct device *dev)
{
struct rtc_device *rtc = to_rtc_device(dev);
struct timerqueue_head *head = &rtc->timerqueue;
struct timerqueue_node *node;
mutex_lock(&rtc->ops_lock);
while ((node = timerqueue_getnext(head)))
timerqueue_del(head, node);
mutex_unlock(&rtc->ops_lock);
cancel_work_sync(&rtc->irqwork);
ida_free(&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
const struct class rtc_class = {
.name = "rtc",
.pm = RTC_CLASS_DEV_PM_OPS,
};
/* 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;
set_bit(RTC_FEATURE_ALARM, rtc->features);
set_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
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_alloc_range(&rtc_ida, of_id, of_id, GFP_KERNEL);
if (id < 0)
dev_warn(dev, "/aliases ID %d not available\n", of_id);
}
if (id < 0)
id = ida_alloc(&rtc_ida, 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;
}
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);
if (!test_bit(RTC_NO_CDEV, &rtc->flags))
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_free(&rtc_ida, id);
return ERR_PTR(-ENOMEM);
}
rtc->id = id;
rtc->dev.parent = dev;
err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
if (err)
return ERR_PTR(err);
err = dev_set_name(&rtc->dev, "rtc%d", id);
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;
}
if (!rtc->ops->set_alarm)
clear_bit(RTC_FEATURE_ALARM, rtc->features);
if (rtc->ops->set_offset)
set_bit(RTC_FEATURE_CORRECTION, rtc->features);
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) {
set_bit(RTC_NO_CDEV, &rtc->flags);
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)
{
int err;
err = class_register(&rtc_class);
if (err)
return err;
rtc_dev_init();
return 0;
}
subsys_initcall(rtc_init);
