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 struct class *rtc_class; 25 26 static void rtc_device_release(struct device *dev) 27 { 28 struct rtc_device *rtc = to_rtc_device(dev); 29 struct timerqueue_head *head = &rtc->timerqueue; 30 struct timerqueue_node *node; 31 32 mutex_lock(&rtc->ops_lock); 33 while ((node = timerqueue_getnext(head))) 34 timerqueue_del(head, node); 35 mutex_unlock(&rtc->ops_lock); 36 37 cancel_work_sync(&rtc->irqwork); 38 39 ida_free(&rtc_ida, rtc->id); 40 mutex_destroy(&rtc->ops_lock); 41 kfree(rtc); 42 } 43 44 #ifdef CONFIG_RTC_HCTOSYS_DEVICE 45 /* Result of the last RTC to system clock attempt. */ 46 int rtc_hctosys_ret = -ENODEV; 47 48 /* IMPORTANT: the RTC only stores whole seconds. It is arbitrary 49 * whether it stores the most close value or the value with partial 50 * seconds truncated. However, it is important that we use it to store 51 * the truncated value. This is because otherwise it is necessary, 52 * in an rtc sync function, to read both xtime.tv_sec and 53 * xtime.tv_nsec. On some processors (i.e. ARM), an atomic read 54 * of >32bits is not possible. So storing the most close value would 55 * slow down the sync API. So here we have the truncated value and 56 * the best guess is to add 0.5s. 57 */ 58 59 static void rtc_hctosys(struct rtc_device *rtc) 60 { 61 int err; 62 struct rtc_time tm; 63 struct timespec64 tv64 = { 64 .tv_nsec = NSEC_PER_SEC >> 1, 65 }; 66 67 err = rtc_read_time(rtc, &tm); 68 if (err) { 69 dev_err(rtc->dev.parent, 70 "hctosys: unable to read the hardware clock\n"); 71 goto err_read; 72 } 73 74 tv64.tv_sec = rtc_tm_to_time64(&tm); 75 76 #if BITS_PER_LONG == 32 77 if (tv64.tv_sec > INT_MAX) { 78 err = -ERANGE; 79 goto err_read; 80 } 81 #endif 82 83 err = do_settimeofday64(&tv64); 84 85 dev_info(rtc->dev.parent, "setting system clock to %ptR UTC (%lld)\n", 86 &tm, (long long)tv64.tv_sec); 87 88 err_read: 89 rtc_hctosys_ret = err; 90 } 91 #endif 92 93 #if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE) 94 /* 95 * On suspend(), measure the delta between one RTC and the 96 * system's wall clock; restore it on resume(). 97 */ 98 99 static struct timespec64 old_rtc, old_system, old_delta; 100 101 static int rtc_suspend(struct device *dev) 102 { 103 struct rtc_device *rtc = to_rtc_device(dev); 104 struct rtc_time tm; 105 struct timespec64 delta, delta_delta; 106 int err; 107 108 if (timekeeping_rtc_skipsuspend()) 109 return 0; 110 111 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) 112 return 0; 113 114 /* snapshot the current RTC and system time at suspend*/ 115 err = rtc_read_time(rtc, &tm); 116 if (err < 0) { 117 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev)); 118 return 0; 119 } 120 121 ktime_get_real_ts64(&old_system); 122 old_rtc.tv_sec = rtc_tm_to_time64(&tm); 123 124 /* 125 * To avoid drift caused by repeated suspend/resumes, 126 * which each can add ~1 second drift error, 127 * try to compensate so the difference in system time 128 * and rtc time stays close to constant. 129 */ 130 delta = timespec64_sub(old_system, old_rtc); 131 delta_delta = timespec64_sub(delta, old_delta); 132 if (delta_delta.tv_sec < -2 || delta_delta.tv_sec >= 2) { 133 /* 134 * if delta_delta is too large, assume time correction 135 * has occurred and set old_delta to the current delta. 136 */ 137 old_delta = delta; 138 } else { 139 /* Otherwise try to adjust old_system to compensate */ 140 old_system = timespec64_sub(old_system, delta_delta); 141 } 142 143 return 0; 144 } 145 146 static int rtc_resume(struct device *dev) 147 { 148 struct rtc_device *rtc = to_rtc_device(dev); 149 struct rtc_time tm; 150 struct timespec64 new_system, new_rtc; 151 struct timespec64 sleep_time; 152 int err; 153 154 if (timekeeping_rtc_skipresume()) 155 return 0; 156 157 rtc_hctosys_ret = -ENODEV; 158 if (strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE) != 0) 159 return 0; 160 161 /* snapshot the current rtc and system time at resume */ 162 ktime_get_real_ts64(&new_system); 163 err = rtc_read_time(rtc, &tm); 164 if (err < 0) { 165 pr_debug("%s: fail to read rtc time\n", dev_name(&rtc->dev)); 166 return 0; 167 } 168 169 new_rtc.tv_sec = rtc_tm_to_time64(&tm); 170 new_rtc.tv_nsec = 0; 171 172 if (new_rtc.tv_sec < old_rtc.tv_sec) { 173 pr_debug("%s: time travel!\n", dev_name(&rtc->dev)); 174 return 0; 175 } 176 177 /* calculate the RTC time delta (sleep time)*/ 178 sleep_time = timespec64_sub(new_rtc, old_rtc); 179 180 /* 181 * Since these RTC suspend/resume handlers are not called 182 * at the very end of suspend or the start of resume, 183 * some run-time may pass on either sides of the sleep time 184 * so subtract kernel run-time between rtc_suspend to rtc_resume 185 * to keep things accurate. 186 */ 187 sleep_time = timespec64_sub(sleep_time, 188 timespec64_sub(new_system, old_system)); 189 190 if (sleep_time.tv_sec >= 0) 191 timekeeping_inject_sleeptime64(&sleep_time); 192 rtc_hctosys_ret = 0; 193 return 0; 194 } 195 196 static SIMPLE_DEV_PM_OPS(rtc_class_dev_pm_ops, rtc_suspend, rtc_resume); 197 #define RTC_CLASS_DEV_PM_OPS (&rtc_class_dev_pm_ops) 198 #else 199 #define RTC_CLASS_DEV_PM_OPS NULL 200 #endif 201 202 /* Ensure the caller will set the id before releasing the device */ 203 static struct rtc_device *rtc_allocate_device(void) 204 { 205 struct rtc_device *rtc; 206 207 rtc = kzalloc(sizeof(*rtc), GFP_KERNEL); 208 if (!rtc) 209 return NULL; 210 211 device_initialize(&rtc->dev); 212 213 /* 214 * Drivers can revise this default after allocating the device. 215 * The default is what most RTCs do: Increment seconds exactly one 216 * second after the write happened. This adds a default transport 217 * time of 5ms which is at least halfways close to reality. 218 */ 219 rtc->set_offset_nsec = NSEC_PER_SEC + 5 * NSEC_PER_MSEC; 220 221 rtc->irq_freq = 1; 222 rtc->max_user_freq = 64; 223 rtc->dev.class = rtc_class; 224 rtc->dev.groups = rtc_get_dev_attribute_groups(); 225 rtc->dev.release = rtc_device_release; 226 227 mutex_init(&rtc->ops_lock); 228 spin_lock_init(&rtc->irq_lock); 229 init_waitqueue_head(&rtc->irq_queue); 230 231 /* Init timerqueue */ 232 timerqueue_init_head(&rtc->timerqueue); 233 INIT_WORK(&rtc->irqwork, rtc_timer_do_work); 234 /* Init aie timer */ 235 rtc_timer_init(&rtc->aie_timer, rtc_aie_update_irq, rtc); 236 /* Init uie timer */ 237 rtc_timer_init(&rtc->uie_rtctimer, rtc_uie_update_irq, rtc); 238 /* Init pie timer */ 239 hrtimer_init(&rtc->pie_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 240 rtc->pie_timer.function = rtc_pie_update_irq; 241 rtc->pie_enabled = 0; 242 243 set_bit(RTC_FEATURE_ALARM, rtc->features); 244 set_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features); 245 246 return rtc; 247 } 248 249 static int rtc_device_get_id(struct device *dev) 250 { 251 int of_id = -1, id = -1; 252 253 if (dev->of_node) 254 of_id = of_alias_get_id(dev->of_node, "rtc"); 255 else if (dev->parent && dev->parent->of_node) 256 of_id = of_alias_get_id(dev->parent->of_node, "rtc"); 257 258 if (of_id >= 0) { 259 id = ida_alloc_range(&rtc_ida, of_id, of_id, GFP_KERNEL); 260 if (id < 0) 261 dev_warn(dev, "/aliases ID %d not available\n", of_id); 262 } 263 264 if (id < 0) 265 id = ida_alloc(&rtc_ida, GFP_KERNEL); 266 267 return id; 268 } 269 270 static void rtc_device_get_offset(struct rtc_device *rtc) 271 { 272 time64_t range_secs; 273 u32 start_year; 274 int ret; 275 276 /* 277 * If RTC driver did not implement the range of RTC hardware device, 278 * then we can not expand the RTC range by adding or subtracting one 279 * offset. 280 */ 281 if (rtc->range_min == rtc->range_max) 282 return; 283 284 ret = device_property_read_u32(rtc->dev.parent, "start-year", 285 &start_year); 286 if (!ret) { 287 rtc->start_secs = mktime64(start_year, 1, 1, 0, 0, 0); 288 rtc->set_start_time = true; 289 } 290 291 /* 292 * If user did not implement the start time for RTC driver, then no 293 * need to expand the RTC range. 294 */ 295 if (!rtc->set_start_time) 296 return; 297 298 range_secs = rtc->range_max - rtc->range_min + 1; 299 300 /* 301 * If the start_secs is larger than the maximum seconds (rtc->range_max) 302 * supported by RTC hardware or the maximum seconds of new expanded 303 * range (start_secs + rtc->range_max - rtc->range_min) is less than 304 * rtc->range_min, which means the minimum seconds (rtc->range_min) of 305 * RTC hardware will be mapped to start_secs by adding one offset, so 306 * the offset seconds calculation formula should be: 307 * rtc->offset_secs = rtc->start_secs - rtc->range_min; 308 * 309 * If the start_secs is larger than the minimum seconds (rtc->range_min) 310 * supported by RTC hardware, then there is one region is overlapped 311 * between the original RTC hardware range and the new expanded range, 312 * and this overlapped region do not need to be mapped into the new 313 * expanded range due to it is valid for RTC device. So the minimum 314 * seconds of RTC hardware (rtc->range_min) should be mapped to 315 * rtc->range_max + 1, then the offset seconds formula should be: 316 * rtc->offset_secs = rtc->range_max - rtc->range_min + 1; 317 * 318 * If the start_secs is less than the minimum seconds (rtc->range_min), 319 * which is similar to case 2. So the start_secs should be mapped to 320 * start_secs + rtc->range_max - rtc->range_min + 1, then the 321 * offset seconds formula should be: 322 * rtc->offset_secs = -(rtc->range_max - rtc->range_min + 1); 323 * 324 * Otherwise the offset seconds should be 0. 325 */ 326 if (rtc->start_secs > rtc->range_max || 327 rtc->start_secs + range_secs - 1 < rtc->range_min) 328 rtc->offset_secs = rtc->start_secs - rtc->range_min; 329 else if (rtc->start_secs > rtc->range_min) 330 rtc->offset_secs = range_secs; 331 else if (rtc->start_secs < rtc->range_min) 332 rtc->offset_secs = -range_secs; 333 else 334 rtc->offset_secs = 0; 335 } 336 337 static void devm_rtc_unregister_device(void *data) 338 { 339 struct rtc_device *rtc = data; 340 341 mutex_lock(&rtc->ops_lock); 342 /* 343 * Remove innards of this RTC, then disable it, before 344 * letting any rtc_class_open() users access it again 345 */ 346 rtc_proc_del_device(rtc); 347 if (!test_bit(RTC_NO_CDEV, &rtc->flags)) 348 cdev_device_del(&rtc->char_dev, &rtc->dev); 349 rtc->ops = NULL; 350 mutex_unlock(&rtc->ops_lock); 351 } 352 353 static void devm_rtc_release_device(void *res) 354 { 355 struct rtc_device *rtc = res; 356 357 put_device(&rtc->dev); 358 } 359 360 struct rtc_device *devm_rtc_allocate_device(struct device *dev) 361 { 362 struct rtc_device *rtc; 363 int id, err; 364 365 id = rtc_device_get_id(dev); 366 if (id < 0) 367 return ERR_PTR(id); 368 369 rtc = rtc_allocate_device(); 370 if (!rtc) { 371 ida_free(&rtc_ida, id); 372 return ERR_PTR(-ENOMEM); 373 } 374 375 rtc->id = id; 376 rtc->dev.parent = dev; 377 err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc); 378 if (err) 379 return ERR_PTR(err); 380 381 err = dev_set_name(&rtc->dev, "rtc%d", id); 382 if (err) 383 return ERR_PTR(err); 384 385 return rtc; 386 } 387 EXPORT_SYMBOL_GPL(devm_rtc_allocate_device); 388 389 int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc) 390 { 391 struct rtc_wkalrm alrm; 392 int err; 393 394 if (!rtc->ops) { 395 dev_dbg(&rtc->dev, "no ops set\n"); 396 return -EINVAL; 397 } 398 399 if (!rtc->ops->set_alarm) 400 clear_bit(RTC_FEATURE_ALARM, rtc->features); 401 402 if (rtc->ops->set_offset) 403 set_bit(RTC_FEATURE_CORRECTION, rtc->features); 404 405 rtc->owner = owner; 406 rtc_device_get_offset(rtc); 407 408 /* Check to see if there is an ALARM already set in hw */ 409 err = __rtc_read_alarm(rtc, &alrm); 410 if (!err && !rtc_valid_tm(&alrm.time)) 411 rtc_initialize_alarm(rtc, &alrm); 412 413 rtc_dev_prepare(rtc); 414 415 err = cdev_device_add(&rtc->char_dev, &rtc->dev); 416 if (err) { 417 set_bit(RTC_NO_CDEV, &rtc->flags); 418 dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n", 419 MAJOR(rtc->dev.devt), rtc->id); 420 } else { 421 dev_dbg(rtc->dev.parent, "char device (%d:%d)\n", 422 MAJOR(rtc->dev.devt), rtc->id); 423 } 424 425 rtc_proc_add_device(rtc); 426 427 dev_info(rtc->dev.parent, "registered as %s\n", 428 dev_name(&rtc->dev)); 429 430 #ifdef CONFIG_RTC_HCTOSYS_DEVICE 431 if (!strcmp(dev_name(&rtc->dev), CONFIG_RTC_HCTOSYS_DEVICE)) 432 rtc_hctosys(rtc); 433 #endif 434 435 return devm_add_action_or_reset(rtc->dev.parent, 436 devm_rtc_unregister_device, rtc); 437 } 438 EXPORT_SYMBOL_GPL(__devm_rtc_register_device); 439 440 /** 441 * devm_rtc_device_register - resource managed rtc_device_register() 442 * @dev: the device to register 443 * @name: the name of the device (unused) 444 * @ops: the rtc operations structure 445 * @owner: the module owner 446 * 447 * @return a struct rtc on success, or an ERR_PTR on error 448 * 449 * Managed rtc_device_register(). The rtc_device returned from this function 450 * are automatically freed on driver detach. 451 * This function is deprecated, use devm_rtc_allocate_device and 452 * rtc_register_device instead 453 */ 454 struct rtc_device *devm_rtc_device_register(struct device *dev, 455 const char *name, 456 const struct rtc_class_ops *ops, 457 struct module *owner) 458 { 459 struct rtc_device *rtc; 460 int err; 461 462 rtc = devm_rtc_allocate_device(dev); 463 if (IS_ERR(rtc)) 464 return rtc; 465 466 rtc->ops = ops; 467 468 err = __devm_rtc_register_device(owner, rtc); 469 if (err) 470 return ERR_PTR(err); 471 472 return rtc; 473 } 474 EXPORT_SYMBOL_GPL(devm_rtc_device_register); 475 476 static int __init rtc_init(void) 477 { 478 rtc_class = class_create("rtc"); 479 if (IS_ERR(rtc_class)) { 480 pr_err("couldn't create class\n"); 481 return PTR_ERR(rtc_class); 482 } 483 rtc_class->pm = RTC_CLASS_DEV_PM_OPS; 484 rtc_dev_init(); 485 return 0; 486 } 487 subsys_initcall(rtc_init); 488