1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * RTC subsystem, base class 4 * 5 * Copyright (C) 2005 Tower Technologies 6 * Author: Alessandro Zummo <a.zummo@towertech.it> 7 * 8 * class skeleton from drivers/hwmon/hwmon.c 9 */ 10 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 12 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 23 static DEFINE_IDA(rtc_ida); 24 25 static 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_DEVICE 44 /* Result of the last RTC to system clock attempt. */ 45 int rtc_hctosys_ret = -ENODEV; 46 47 /* IMPORTANT: the RTC only stores whole seconds. It is arbitrary 48 * whether it stores the most close value or the value with partial 49 * seconds truncated. However, it is important that we use it to store 50 * the truncated value. This is because otherwise it is necessary, 51 * in an rtc sync function, to read both xtime.tv_sec and 52 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read 53 * of >32bits is not possible. So storing the most close value would 54 * slow down the sync API. So here we have the truncated value and 55 * the best guess is to add 0.5s. 56 */ 57 58 static 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 == 32 76 if (tv64.tv_sec > INT_MAX) { 77 err = -ERANGE; 78 goto err_read; 79 } 80 #endif 81 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 87 err_read: 88 rtc_hctosys_ret = err; 89 } 90 #endif 91 92 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE) 93 /* 94 * On suspend(), measure the delta between one RTC and the 95 * system's wall clock; restore it on resume(). 96 */ 97 98 static struct timespec64 old_rtc, old_system, old_delta; 99 100 static 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 time 127 * 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 correction 134 * 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 } 144 145 static 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 called 181 * at the very end of suspend or the start of resume, 182 * some run-time may pass on either sides of the sleep time 183 * so subtract kernel run-time between rtc_suspend to rtc_resume 184 * 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 } 194 195 static 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 #else 198 #define RTC_CLASS_DEV_PM_OPS NULL 199 #endif 200 201 const 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 */ 207 static 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 one 220 * second after the write happened. This adds a default transport 221 * 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 } 252 253 static 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 } 273 274 static 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 one 283 * 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 no 297 * 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 expanded 307 * range (start_secs + rtc->range_max - rtc->range_min) is less than 308 * rtc->range_min, which means the minimum seconds (rtc->range_min) of 309 * RTC hardware will be mapped to start_secs by adding one offset, so 310 * 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 overlapped 315 * between the original RTC hardware range and the new expanded range, 316 * and this overlapped region do not need to be mapped into the new 317 * expanded range due to it is valid for RTC device. So the minimum 318 * seconds of RTC hardware (rtc->range_min) should be mapped to 319 * 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 to 324 * start_secs + rtc->range_max - rtc->range_min + 1, then the 325 * 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 else 338 rtc->offset_secs = 0; 339 } 340 341 static 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, before 348 * letting any rtc_class_open() users access it again 349 */ 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 } 356 357 static void devm_rtc_release_device(void *res) 358 { 359 struct rtc_device *rtc = res; 360 361 put_device(&rtc->dev); 362 } 363 364 struct 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 } 391 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device); 392 393 int __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_DEVICE 435 if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE)) 436 rtc_hctosys(rtc); 437 #endif 438 439 return devm_add_action_or_reset(rtc->dev.parent, 440 devm_rtc_unregister_device, rtc); 441 } 442 EXPORT_SYMBOL_GPL(__devm_rtc_register_device); 443 444 /** 445 * devm_rtc_device_register - resource managed rtc_device_register() 446 * @dev: the device to register 447 * @name: the name of the device (unused) 448 * @ops: the rtc operations structure 449 * @owner: the module owner 450 * 451 * @return a struct rtc on success, or an ERR_PTR on error 452 * 453 * Managed rtc_device_register(). The rtc_device returned from this function 454 * are automatically freed on driver detach. 455 * This function is deprecated, use devm_rtc_allocate_device and 456 * rtc_register_device instead 457 */ 458 struct 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 } 478 EXPORT_SYMBOL_GPL(devm_rtc_device_register); 479 480 static 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 } 492 subsys_initcall(rtc_init); 493