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1// SPDX-License-Identifier: GPL-2.02/*3 * RTC subsystem, base class4 *5 * Copyright (C) 2005 Tower Technologies6 * Author: Alessandro Zummo <a.zummo@towertech.it>7 *8 * class skeleton from drivers/hwmon/hwmon.c9 */10 11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt12 13#include <linux/module.h>14#include <linux/of.h>15#include <linux/rtc.h>16#include <linux/kdev_t.h>17#include <linux/idr.h>18#include <linux/slab.h>19#include <linux/workqueue.h>20 21#include "rtc-core.h"22 23static DEFINE_IDA(rtc_ida);24 25static void rtc_device_release(struct device *dev)26{27 struct rtc_device *rtc = to_rtc_device(dev);28 struct timerqueue_head *head = &rtc->timerqueue;29 struct timerqueue_node *node;30 31 mutex_lock(&rtc->ops_lock);32 while ((node = timerqueue_getnext(head)))33 timerqueue_del(head, node);34 mutex_unlock(&rtc->ops_lock);35 36 cancel_work_sync(&rtc->irqwork);37 38 ida_free(&rtc_ida, rtc->id);39 mutex_destroy(&rtc->ops_lock);40 kfree(rtc);41}42 43#ifdef CONFIG_RTC_HCTOSYS_DEVICE44/* Result of the last RTC to system clock attempt. */45int rtc_hctosys_ret = -ENODEV;46 47/* IMPORTANT: the RTC only stores whole seconds. It is arbitrary48 * whether it stores the most close value or the value with partial49 * seconds truncated. However, it is important that we use it to store50 * the truncated value. This is because otherwise it is necessary,51 * in an rtc sync function, to read both xtime.tv_sec and52 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read53 * of >32bits is not possible. So storing the most close value would54 * slow down the sync API. So here we have the truncated value and55 * the best guess is to add 0.5s.56 */57 58static void rtc_hctosys(struct rtc_device *rtc)59{60 int err;61 struct rtc_time tm;62 struct timespec64 tv64 = {63 .tv_nsec = NSEC_PER_SEC >> 1,64 };65 66 err = rtc_read_time(rtc, &tm);67 if (err) {68 dev_err(rtc->dev.parent,69 "hctosys: unable to read the hardware clock\n");70 goto err_read;71 }72 73 tv64.tv_sec = rtc_tm_to_time64(&tm);74 75#if BITS_PER_LONG == 3276 if (tv64.tv_sec > INT_MAX) {77 err = -ERANGE;78 goto err_read;79 }80#endif81 82 err = do_settimeofday64(&tv64);83 84 dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n",85 &tm, (long long)tv64.tv_sec);86 87err_read:88 rtc_hctosys_ret = err;89}90#endif91 92#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE)93/*94 * On suspend(), measure the delta between one RTC and the95 * system's wall clock; restore it on resume().96 */97 98static struct timespec64 old_rtc, old_system, old_delta;99 100static int rtc_suspend(struct device *dev)101{102 struct rtc_device *rtc = to_rtc_device(dev);103 struct rtc_time tm;104 struct timespec64 delta, delta_delta;105 int err;106 107 if (timekeeping_rtc_skipsuspend())108 return 0;109 110 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)111 return 0;112 113 /* snapshot the current RTC and system time at suspend*/114 err = rtc_read_time(rtc, &tm);115 if (err < 0) {116 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));117 return 0;118 }119 120 ktime_get_real_ts64(&old_system);121 old_rtc.tv_sec = rtc_tm_to_time64(&tm);122 123 /*124 * To avoid drift caused by repeated suspend/resumes,125 * which each can add ~1 second drift error,126 * try to compensate so the difference in system time127 * and rtc time stays close to constant.128 */129 delta = timespec64_sub(old_system, old_rtc);130 delta_delta = timespec64_sub(delta, old_delta);131 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) {132 /*133 * if delta_delta is too large, assume time correction134 * has occurred and set old_delta to the current delta.135 */136 old_delta = delta;137 } else {138 /* Otherwise try to adjust old_system to compensate */139 old_system = timespec64_sub(old_system, delta_delta);140 }141 142 return 0;143}144 145static int rtc_resume(struct device *dev)146{147 struct rtc_device *rtc = to_rtc_device(dev);148 struct rtc_time tm;149 struct timespec64 new_system, new_rtc;150 struct timespec64 sleep_time;151 int err;152 153 if (timekeeping_rtc_skipresume())154 return 0;155 156 rtc_hctosys_ret = -ENODEV;157 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0)158 return 0;159 160 /* snapshot the current rtc and system time at resume */161 ktime_get_real_ts64(&new_system);162 err = rtc_read_time(rtc, &tm);163 if (err < 0) {164 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev));165 return 0;166 }167 168 new_rtc.tv_sec = rtc_tm_to_time64(&tm);169 new_rtc.tv_nsec = 0;170 171 if (new_rtc.tv_sec < old_rtc.tv_sec) {172 pr_debug("%s: time travel!\n", dev_name(&rtc->dev));173 return 0;174 }175 176 /* calculate the RTC time delta (sleep time)*/177 sleep_time = timespec64_sub(new_rtc, old_rtc);178 179 /*180 * Since these RTC suspend/resume handlers are not called181 * at the very end of suspend or the start of resume,182 * some run-time may pass on either sides of the sleep time183 * so subtract kernel run-time between rtc_suspend to rtc_resume184 * to keep things accurate.185 */186 sleep_time = timespec64_sub(sleep_time,187 timespec64_sub(new_system, old_system));188 189 if (sleep_time.tv_sec >= 0)190 timekeeping_inject_sleeptime64(&sleep_time);191 rtc_hctosys_ret = 0;192 return 0;193}194 195static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume);196#define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops)197#else198#define RTC_CLASS_DEV_PM_OPS NULL199#endif200 201const struct class rtc_class = {202 .name = "rtc",203 .pm = RTC_CLASS_DEV_PM_OPS,204};205 206/* Ensure the caller will set the id before releasing the device */207static struct rtc_device *rtc_allocate_device(void)208{209 struct rtc_device *rtc;210 211 rtc = kzalloc(sizeof(*rtc), GFP_KERNEL);212 if (!rtc)213 return NULL;214 215 device_initialize(&rtc->dev);216 217 /*218 * Drivers can revise this default after allocating the device.219 * The default is what most RTCs do: Increment seconds exactly one220 * second after the write happened. This adds a default transport221 * time of 5ms which is at least halfways close to reality.222 */223 rtc->set_offset_nsec = NSEC_PER_SEC + 5 * NSEC_PER_MSEC;224 225 rtc->irq_freq = 1;226 rtc->max_user_freq = 64;227 rtc->dev.class = &rtc_class;228 rtc->dev.groups = rtc_get_dev_attribute_groups();229 rtc->dev.release = rtc_device_release;230 231 mutex_init(&rtc->ops_lock);232 spin_lock_init(&rtc->irq_lock);233 init_waitqueue_head(&rtc->irq_queue);234 235 /* Init timerqueue */236 timerqueue_init_head(&rtc->timerqueue);237 INIT_WORK(&rtc->irqwork, rtc_timer_do_work);238 /* Init aie timer */239 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc);240 /* Init uie timer */241 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc);242 /* Init pie timer */243 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);244 rtc->pie_timer.function = rtc_pie_update_irq;245 rtc->pie_enabled = 0;246 247 set_bit(RTC_FEATURE_ALARM, rtc->features);248 set_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);249 250 return rtc;251}252 253static int rtc_device_get_id(struct device *dev)254{255 int of_id = -1, id = -1;256 257 if (dev->of_node)258 of_id = of_alias_get_id(dev->of_node, "rtc");259 else if (dev->parent && dev->parent->of_node)260 of_id = of_alias_get_id(dev->parent->of_node, "rtc");261 262 if (of_id >= 0) {263 id = ida_alloc_range(&rtc_ida, of_id, of_id, GFP_KERNEL);264 if (id < 0)265 dev_warn(dev, "/aliases ID %d not available\n", of_id);266 }267 268 if (id < 0)269 id = ida_alloc(&rtc_ida, GFP_KERNEL);270 271 return id;272}273 274static void rtc_device_get_offset(struct rtc_device *rtc)275{276 time64_t range_secs;277 u32 start_year;278 int ret;279 280 /*281 * If RTC driver did not implement the range of RTC hardware device,282 * then we can not expand the RTC range by adding or subtracting one283 * offset.284 */285 if (rtc->range_min == rtc->range_max)286 return;287 288 ret = device_property_read_u32(rtc->dev.parent, "start-year",289 &start_year);290 if (!ret) {291 rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0);292 rtc->set_start_time = true;293 }294 295 /*296 * If user did not implement the start time for RTC driver, then no297 * need to expand the RTC range.298 */299 if (!rtc->set_start_time)300 return;301 302 range_secs = rtc->range_max - rtc->range_min + 1;303 304 /*305 * If the start_secs is larger than the maximum seconds (rtc->range_max)306 * supported by RTC hardware or the maximum seconds of new expanded307 * range (start_secs + rtc->range_max - rtc->range_min) is less than308 * rtc->range_min, which means the minimum seconds (rtc->range_min) of309 * RTC hardware will be mapped to start_secs by adding one offset, so310 * the offset seconds calculation formula should be:311 * rtc->offset_secs = rtc->start_secs - rtc->range_min;312 *313 * If the start_secs is larger than the minimum seconds (rtc->range_min)314 * supported by RTC hardware, then there is one region is overlapped315 * between the original RTC hardware range and the new expanded range,316 * and this overlapped region do not need to be mapped into the new317 * expanded range due to it is valid for RTC device. So the minimum318 * seconds of RTC hardware (rtc->range_min) should be mapped to319 * rtc->range_max + 1, then the offset seconds formula should be:320 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1;321 *322 * If the start_secs is less than the minimum seconds (rtc->range_min),323 * which is similar to case 2. So the start_secs should be mapped to324 * start_secs + rtc->range_max - rtc->range_min + 1, then the325 * offset seconds formula should be:326 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1);327 *328 * Otherwise the offset seconds should be 0.329 */330 if (rtc->start_secs > rtc->range_max ||331 rtc->start_secs + range_secs - 1 < rtc->range_min)332 rtc->offset_secs = rtc->start_secs - rtc->range_min;333 else if (rtc->start_secs > rtc->range_min)334 rtc->offset_secs = range_secs;335 else if (rtc->start_secs < rtc->range_min)336 rtc->offset_secs = -range_secs;337 else338 rtc->offset_secs = 0;339}340 341static void devm_rtc_unregister_device(void *data)342{343 struct rtc_device *rtc = data;344 345 mutex_lock(&rtc->ops_lock);346 /*347 * Remove innards of this RTC, then disable it, before348 * letting any rtc_class_open() users access it again349 */350 rtc_proc_del_device(rtc);351 if (!test_bit(RTC_NO_CDEV, &rtc->flags))352 cdev_device_del(&rtc->char_dev, &rtc->dev);353 rtc->ops = NULL;354 mutex_unlock(&rtc->ops_lock);355}356 357static void devm_rtc_release_device(void *res)358{359 struct rtc_device *rtc = res;360 361 put_device(&rtc->dev);362}363 364struct rtc_device *devm_rtc_allocate_device(struct device *dev)365{366 struct rtc_device *rtc;367 int id, err;368 369 id = rtc_device_get_id(dev);370 if (id < 0)371 return ERR_PTR(id);372 373 rtc = rtc_allocate_device();374 if (!rtc) {375 ida_free(&rtc_ida, id);376 return ERR_PTR(-ENOMEM);377 }378 379 rtc->id = id;380 rtc->dev.parent = dev;381 err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);382 if (err)383 return ERR_PTR(err);384 385 err = dev_set_name(&rtc->dev, "rtc%d", id);386 if (err)387 return ERR_PTR(err);388 389 return rtc;390}391EXPORT_SYMBOL_GPL(devm_rtc_allocate_device);392 393int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc)394{395 struct rtc_wkalrm alrm;396 int err;397 398 if (!rtc->ops) {399 dev_dbg(&rtc->dev, "no ops set\n");400 return -EINVAL;401 }402 403 if (!rtc->ops->set_alarm)404 clear_bit(RTC_FEATURE_ALARM, rtc->features);405 406 if (rtc->ops->set_offset)407 set_bit(RTC_FEATURE_CORRECTION, rtc->features);408 409 rtc->owner = owner;410 rtc_device_get_offset(rtc);411 412 /* Check to see if there is an ALARM already set in hw */413 err = __rtc_read_alarm(rtc, &alrm);414 if (!err && !rtc_valid_tm(&alrm.time))415 rtc_initialize_alarm(rtc, &alrm);416 417 rtc_dev_prepare(rtc);418 419 err = cdev_device_add(&rtc->char_dev, &rtc->dev);420 if (err) {421 set_bit(RTC_NO_CDEV, &rtc->flags);422 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n",423 MAJOR(rtc->dev.devt), rtc->id);424 } else {425 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n",426 MAJOR(rtc->dev.devt), rtc->id);427 }428 429 rtc_proc_add_device(rtc);430 431 dev_info(rtc->dev.parent, "registered as %s\n",432 dev_name(&rtc->dev));433 434#ifdef CONFIG_RTC_HCTOSYS_DEVICE435 if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE))436 rtc_hctosys(rtc);437#endif438 439 return devm_add_action_or_reset(rtc->dev.parent,440 devm_rtc_unregister_device, rtc);441}442EXPORT_SYMBOL_GPL(__devm_rtc_register_device);443 444/**445 * devm_rtc_device_register - resource managed rtc_device_register()446 * @dev: the device to register447 * @name: the name of the device (unused)448 * @ops: the rtc operations structure449 * @owner: the module owner450 *451 * @return a struct rtc on success, or an ERR_PTR on error452 *453 * Managed rtc_device_register(). The rtc_device returned from this function454 * are automatically freed on driver detach.455 * This function is deprecated, use devm_rtc_allocate_device and456 * rtc_register_device instead457 */458struct rtc_device *devm_rtc_device_register(struct device *dev,459 const char *name,460 const struct rtc_class_ops *ops,461 struct module *owner)462{463 struct rtc_device *rtc;464 int err;465 466 rtc = devm_rtc_allocate_device(dev);467 if (IS_ERR(rtc))468 return rtc;469 470 rtc->ops = ops;471 472 err = __devm_rtc_register_device(owner, rtc);473 if (err)474 return ERR_PTR(err);475 476 return rtc;477}478EXPORT_SYMBOL_GPL(devm_rtc_device_register);479 480static int __init rtc_init(void)481{482 int err;483 484 err = class_register(&rtc_class);485 if (err)486 return err;487 488 rtc_dev_init();489 490 return 0;491}492subsys_initcall(rtc_init);493