diff options
Diffstat (limited to 'drivers/rtc/class.c')
| -rw-r--r-- | drivers/rtc/class.c | 487 |
1 files changed, 487 insertions, 0 deletions
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c new file mode 100644 index 000000000..625effe6c --- /dev/null +++ b/drivers/rtc/class.c @@ -0,0 +1,487 @@ +// 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); + 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_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); |