// 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); 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. */ 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)); #ifdef CONFIG_RTC_HCTOSYS_DEVICE if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE)) rtc_hctosys(rtc); #endif 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);