1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * RTC subsystem, dev interface 4 * 5 * Copyright (C) 2005 Tower Technologies 6 * Author: Alessandro Zummo <a.zummo@towertech.it> 7 * 8 * based on arch/arm/common/rtctime.c 9 */ 10 11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 12 13 #include <linux/compat.h> 14 #include <linux/module.h> 15 #include <linux/rtc.h> 16 #include <linux/sched/signal.h> 17 #include "rtc-core.h" 18 19 static dev_t rtc_devt; 20 21 #define RTC_DEV_MAX 16 /* 16 RTCs should be enough for everyone... */ 22 23 static int rtc_dev_open(struct inode *inode, struct file *file) 24 { 25 struct rtc_device *rtc = container_of(inode->i_cdev, 26 struct rtc_device, char_dev); 27 28 if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags)) 29 return -EBUSY; 30 31 file->private_data = rtc; 32 33 spin_lock_irq(&rtc->irq_lock); 34 rtc->irq_data = 0; 35 spin_unlock_irq(&rtc->irq_lock); 36 37 return 0; 38 } 39 40 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL 41 /* 42 * Routine to poll RTC seconds field for change as often as possible, 43 * after first RTC_UIE use timer to reduce polling 44 */ 45 static void rtc_uie_task(struct work_struct *work) 46 { 47 struct rtc_device *rtc = 48 container_of(work, struct rtc_device, uie_task); 49 struct rtc_time tm; 50 int num = 0; 51 int err; 52 53 err = rtc_read_time(rtc, &tm); 54 55 spin_lock_irq(&rtc->irq_lock); 56 if (rtc->stop_uie_polling || err) { 57 rtc->uie_task_active = 0; 58 } else if (rtc->oldsecs != tm.tm_sec) { 59 num = (tm.tm_sec + 60 - rtc->oldsecs) % 60; 60 rtc->oldsecs = tm.tm_sec; 61 rtc->uie_timer.expires = jiffies + HZ - (HZ / 10); 62 rtc->uie_timer_active = 1; 63 rtc->uie_task_active = 0; 64 add_timer(&rtc->uie_timer); 65 } else if (schedule_work(&rtc->uie_task) == 0) { 66 rtc->uie_task_active = 0; 67 } 68 spin_unlock_irq(&rtc->irq_lock); 69 if (num) 70 rtc_handle_legacy_irq(rtc, num, RTC_UF); 71 } 72 73 static void rtc_uie_timer(struct timer_list *t) 74 { 75 struct rtc_device *rtc = from_timer(rtc, t, uie_timer); 76 unsigned long flags; 77 78 spin_lock_irqsave(&rtc->irq_lock, flags); 79 rtc->uie_timer_active = 0; 80 rtc->uie_task_active = 1; 81 if ((schedule_work(&rtc->uie_task) == 0)) 82 rtc->uie_task_active = 0; 83 spin_unlock_irqrestore(&rtc->irq_lock, flags); 84 } 85 86 static int clear_uie(struct rtc_device *rtc) 87 { 88 spin_lock_irq(&rtc->irq_lock); 89 if (rtc->uie_irq_active) { 90 rtc->stop_uie_polling = 1; 91 if (rtc->uie_timer_active) { 92 spin_unlock_irq(&rtc->irq_lock); 93 del_timer_sync(&rtc->uie_timer); 94 spin_lock_irq(&rtc->irq_lock); 95 rtc->uie_timer_active = 0; 96 } 97 if (rtc->uie_task_active) { 98 spin_unlock_irq(&rtc->irq_lock); 99 flush_scheduled_work(); 100 spin_lock_irq(&rtc->irq_lock); 101 } 102 rtc->uie_irq_active = 0; 103 } 104 spin_unlock_irq(&rtc->irq_lock); 105 return 0; 106 } 107 108 static int set_uie(struct rtc_device *rtc) 109 { 110 struct rtc_time tm; 111 int err; 112 113 err = rtc_read_time(rtc, &tm); 114 if (err) 115 return err; 116 spin_lock_irq(&rtc->irq_lock); 117 if (!rtc->uie_irq_active) { 118 rtc->uie_irq_active = 1; 119 rtc->stop_uie_polling = 0; 120 rtc->oldsecs = tm.tm_sec; 121 rtc->uie_task_active = 1; 122 if (schedule_work(&rtc->uie_task) == 0) 123 rtc->uie_task_active = 0; 124 } 125 rtc->irq_data = 0; 126 spin_unlock_irq(&rtc->irq_lock); 127 return 0; 128 } 129 130 int rtc_dev_update_irq_enable_emul(struct rtc_device *rtc, unsigned int enabled) 131 { 132 if (enabled) 133 return set_uie(rtc); 134 else 135 return clear_uie(rtc); 136 } 137 EXPORT_SYMBOL(rtc_dev_update_irq_enable_emul); 138 139 #endif /* CONFIG_RTC_INTF_DEV_UIE_EMUL */ 140 141 static ssize_t 142 rtc_dev_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 143 { 144 struct rtc_device *rtc = file->private_data; 145 146 DECLARE_WAITQUEUE(wait, current); 147 unsigned long data; 148 ssize_t ret; 149 150 if (count != sizeof(unsigned int) && count < sizeof(unsigned long)) 151 return -EINVAL; 152 153 add_wait_queue(&rtc->irq_queue, &wait); 154 do { 155 __set_current_state(TASK_INTERRUPTIBLE); 156 157 spin_lock_irq(&rtc->irq_lock); 158 data = rtc->irq_data; 159 rtc->irq_data = 0; 160 spin_unlock_irq(&rtc->irq_lock); 161 162 if (data != 0) { 163 ret = 0; 164 break; 165 } 166 if (file->f_flags & O_NONBLOCK) { 167 ret = -EAGAIN; 168 break; 169 } 170 if (signal_pending(current)) { 171 ret = -ERESTARTSYS; 172 break; 173 } 174 schedule(); 175 } while (1); 176 set_current_state(TASK_RUNNING); 177 remove_wait_queue(&rtc->irq_queue, &wait); 178 179 if (ret == 0) { 180 if (sizeof(int) != sizeof(long) && 181 count == sizeof(unsigned int)) 182 ret = put_user(data, (unsigned int __user *)buf) ?: 183 sizeof(unsigned int); 184 else 185 ret = put_user(data, (unsigned long __user *)buf) ?: 186 sizeof(unsigned long); 187 } 188 return ret; 189 } 190 191 static __poll_t rtc_dev_poll(struct file *file, poll_table *wait) 192 { 193 struct rtc_device *rtc = file->private_data; 194 unsigned long data; 195 196 poll_wait(file, &rtc->irq_queue, wait); 197 198 data = rtc->irq_data; 199 200 return (data != 0) ? (EPOLLIN | EPOLLRDNORM) : 0; 201 } 202 203 static long rtc_dev_ioctl(struct file *file, 204 unsigned int cmd, unsigned long arg) 205 { 206 int err = 0; 207 struct rtc_device *rtc = file->private_data; 208 const struct rtc_class_ops *ops = rtc->ops; 209 struct rtc_time tm; 210 struct rtc_wkalrm alarm; 211 void __user *uarg = (void __user *)arg; 212 213 err = mutex_lock_interruptible(&rtc->ops_lock); 214 if (err) 215 return err; 216 217 /* check that the calling task has appropriate permissions 218 * for certain ioctls. doing this check here is useful 219 * to avoid duplicate code in each driver. 220 */ 221 switch (cmd) { 222 case RTC_EPOCH_SET: 223 case RTC_SET_TIME: 224 if (!capable(CAP_SYS_TIME)) 225 err = -EACCES; 226 break; 227 228 case RTC_IRQP_SET: 229 if (arg > rtc->max_user_freq && !capable(CAP_SYS_RESOURCE)) 230 err = -EACCES; 231 break; 232 233 case RTC_PIE_ON: 234 if (rtc->irq_freq > rtc->max_user_freq && 235 !capable(CAP_SYS_RESOURCE)) 236 err = -EACCES; 237 break; 238 } 239 240 if (err) 241 goto done; 242 243 /* 244 * Drivers *SHOULD NOT* provide ioctl implementations 245 * for these requests. Instead, provide methods to 246 * support the following code, so that the RTC's main 247 * features are accessible without using ioctls. 248 * 249 * RTC and alarm times will be in UTC, by preference, 250 * but dual-booting with MS-Windows implies RTCs must 251 * use the local wall clock time. 252 */ 253 254 switch (cmd) { 255 case RTC_ALM_READ: 256 mutex_unlock(&rtc->ops_lock); 257 258 err = rtc_read_alarm(rtc, &alarm); 259 if (err < 0) 260 return err; 261 262 if (copy_to_user(uarg, &alarm.time, sizeof(tm))) 263 err = -EFAULT; 264 return err; 265 266 case RTC_ALM_SET: 267 mutex_unlock(&rtc->ops_lock); 268 269 if (copy_from_user(&alarm.time, uarg, sizeof(tm))) 270 return -EFAULT; 271 272 alarm.enabled = 0; 273 alarm.pending = 0; 274 alarm.time.tm_wday = -1; 275 alarm.time.tm_yday = -1; 276 alarm.time.tm_isdst = -1; 277 278 /* RTC_ALM_SET alarms may be up to 24 hours in the future. 279 * Rather than expecting every RTC to implement "don't care" 280 * for day/month/year fields, just force the alarm to have 281 * the right values for those fields. 282 * 283 * RTC_WKALM_SET should be used instead. Not only does it 284 * eliminate the need for a separate RTC_AIE_ON call, it 285 * doesn't have the "alarm 23:59:59 in the future" race. 286 * 287 * NOTE: some legacy code may have used invalid fields as 288 * wildcards, exposing hardware "periodic alarm" capabilities. 289 * Not supported here. 290 */ 291 { 292 time64_t now, then; 293 294 err = rtc_read_time(rtc, &tm); 295 if (err < 0) 296 return err; 297 now = rtc_tm_to_time64(&tm); 298 299 alarm.time.tm_mday = tm.tm_mday; 300 alarm.time.tm_mon = tm.tm_mon; 301 alarm.time.tm_year = tm.tm_year; 302 err = rtc_valid_tm(&alarm.time); 303 if (err < 0) 304 return err; 305 then = rtc_tm_to_time64(&alarm.time); 306 307 /* alarm may need to wrap into tomorrow */ 308 if (then < now) { 309 rtc_time64_to_tm(now + 24 * 60 * 60, &tm); 310 alarm.time.tm_mday = tm.tm_mday; 311 alarm.time.tm_mon = tm.tm_mon; 312 alarm.time.tm_year = tm.tm_year; 313 } 314 } 315 316 return rtc_set_alarm(rtc, &alarm); 317 318 case RTC_RD_TIME: 319 mutex_unlock(&rtc->ops_lock); 320 321 err = rtc_read_time(rtc, &tm); 322 if (err < 0) 323 return err; 324 325 if (copy_to_user(uarg, &tm, sizeof(tm))) 326 err = -EFAULT; 327 return err; 328 329 case RTC_SET_TIME: 330 mutex_unlock(&rtc->ops_lock); 331 332 if (copy_from_user(&tm, uarg, sizeof(tm))) 333 return -EFAULT; 334 335 return rtc_set_time(rtc, &tm); 336 337 case RTC_PIE_ON: 338 err = rtc_irq_set_state(rtc, 1); 339 break; 340 341 case RTC_PIE_OFF: 342 err = rtc_irq_set_state(rtc, 0); 343 break; 344 345 case RTC_AIE_ON: 346 mutex_unlock(&rtc->ops_lock); 347 return rtc_alarm_irq_enable(rtc, 1); 348 349 case RTC_AIE_OFF: 350 mutex_unlock(&rtc->ops_lock); 351 return rtc_alarm_irq_enable(rtc, 0); 352 353 case RTC_UIE_ON: 354 mutex_unlock(&rtc->ops_lock); 355 return rtc_update_irq_enable(rtc, 1); 356 357 case RTC_UIE_OFF: 358 mutex_unlock(&rtc->ops_lock); 359 return rtc_update_irq_enable(rtc, 0); 360 361 case RTC_IRQP_SET: 362 err = rtc_irq_set_freq(rtc, arg); 363 break; 364 case RTC_IRQP_READ: 365 err = put_user(rtc->irq_freq, (unsigned long __user *)uarg); 366 break; 367 368 case RTC_WKALM_SET: 369 mutex_unlock(&rtc->ops_lock); 370 if (copy_from_user(&alarm, uarg, sizeof(alarm))) 371 return -EFAULT; 372 373 return rtc_set_alarm(rtc, &alarm); 374 375 case RTC_WKALM_RD: 376 mutex_unlock(&rtc->ops_lock); 377 err = rtc_read_alarm(rtc, &alarm); 378 if (err < 0) 379 return err; 380 381 if (copy_to_user(uarg, &alarm, sizeof(alarm))) 382 err = -EFAULT; 383 return err; 384 385 default: 386 /* Finally try the driver's ioctl interface */ 387 if (ops->ioctl) { 388 err = ops->ioctl(rtc->dev.parent, cmd, arg); 389 if (err == -ENOIOCTLCMD) 390 err = -ENOTTY; 391 } else { 392 err = -ENOTTY; 393 } 394 break; 395 } 396 397 done: 398 mutex_unlock(&rtc->ops_lock); 399 return err; 400 } 401 402 #ifdef CONFIG_COMPAT 403 #define RTC_IRQP_SET32 _IOW('p', 0x0c, __u32) 404 #define RTC_IRQP_READ32 _IOR('p', 0x0b, __u32) 405 #define RTC_EPOCH_SET32 _IOW('p', 0x0e, __u32) 406 407 static long rtc_dev_compat_ioctl(struct file *file, 408 unsigned int cmd, unsigned long arg) 409 { 410 struct rtc_device *rtc = file->private_data; 411 void __user *uarg = compat_ptr(arg); 412 413 switch (cmd) { 414 case RTC_IRQP_READ32: 415 return put_user(rtc->irq_freq, (__u32 __user *)uarg); 416 417 case RTC_IRQP_SET32: 418 /* arg is a plain integer, not pointer */ 419 return rtc_dev_ioctl(file, RTC_IRQP_SET, arg); 420 421 case RTC_EPOCH_SET32: 422 /* arg is a plain integer, not pointer */ 423 return rtc_dev_ioctl(file, RTC_EPOCH_SET, arg); 424 } 425 426 return rtc_dev_ioctl(file, cmd, (unsigned long)uarg); 427 } 428 #endif 429 430 static int rtc_dev_fasync(int fd, struct file *file, int on) 431 { 432 struct rtc_device *rtc = file->private_data; 433 434 return fasync_helper(fd, file, on, &rtc->async_queue); 435 } 436 437 static int rtc_dev_release(struct inode *inode, struct file *file) 438 { 439 struct rtc_device *rtc = file->private_data; 440 441 /* We shut down the repeating IRQs that userspace enabled, 442 * since nothing is listening to them. 443 * - Update (UIE) ... currently only managed through ioctls 444 * - Periodic (PIE) ... also used through rtc_*() interface calls 445 * 446 * Leave the alarm alone; it may be set to trigger a system wakeup 447 * later, or be used by kernel code, and is a one-shot event anyway. 448 */ 449 450 /* Keep ioctl until all drivers are converted */ 451 rtc_dev_ioctl(file, RTC_UIE_OFF, 0); 452 rtc_update_irq_enable(rtc, 0); 453 rtc_irq_set_state(rtc, 0); 454 455 clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags); 456 return 0; 457 } 458 459 static const struct file_operations rtc_dev_fops = { 460 .owner = THIS_MODULE, 461 .llseek = no_llseek, 462 .read = rtc_dev_read, 463 .poll = rtc_dev_poll, 464 .unlocked_ioctl = rtc_dev_ioctl, 465 #ifdef CONFIG_COMPAT 466 .compat_ioctl = rtc_dev_compat_ioctl, 467 #endif 468 .open = rtc_dev_open, 469 .release = rtc_dev_release, 470 .fasync = rtc_dev_fasync, 471 }; 472 473 /* insertion/removal hooks */ 474 475 void rtc_dev_prepare(struct rtc_device *rtc) 476 { 477 if (!rtc_devt) 478 return; 479 480 if (rtc->id >= RTC_DEV_MAX) { 481 dev_dbg(&rtc->dev, "too many RTC devices\n"); 482 return; 483 } 484 485 rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id); 486 487 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL 488 INIT_WORK(&rtc->uie_task, rtc_uie_task); 489 timer_setup(&rtc->uie_timer, rtc_uie_timer, 0); 490 #endif 491 492 cdev_init(&rtc->char_dev, &rtc_dev_fops); 493 rtc->char_dev.owner = rtc->owner; 494 } 495 496 void __init rtc_dev_init(void) 497 { 498 int err; 499 500 err = alloc_chrdev_region(&rtc_devt, 0, RTC_DEV_MAX, "rtc"); 501 if (err < 0) 502 pr_err("failed to allocate char dev region\n"); 503 } 504 505 void __exit rtc_dev_exit(void) 506 { 507 if (rtc_devt) 508 unregister_chrdev_region(rtc_devt, RTC_DEV_MAX); 509 } 510