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