1 /* 2 * RTC subsystem, interface functions 3 * 4 * Copyright (C) 2005 Tower Technologies 5 * Author: Alessandro Zummo <a.zummo@towertech.it> 6 * 7 * based on arch/arm/common/rtctime.c 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 */ 13 14 #include <linux/rtc.h> 15 #include <linux/log2.h> 16 17 int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm) 18 { 19 int err; 20 21 err = mutex_lock_interruptible(&rtc->ops_lock); 22 if (err) 23 return -EBUSY; 24 25 if (!rtc->ops) 26 err = -ENODEV; 27 else if (!rtc->ops->read_time) 28 err = -EINVAL; 29 else { 30 memset(tm, 0, sizeof(struct rtc_time)); 31 err = rtc->ops->read_time(rtc->dev.parent, tm); 32 } 33 34 mutex_unlock(&rtc->ops_lock); 35 return err; 36 } 37 EXPORT_SYMBOL_GPL(rtc_read_time); 38 39 int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm) 40 { 41 int err; 42 43 err = rtc_valid_tm(tm); 44 if (err != 0) 45 return err; 46 47 err = mutex_lock_interruptible(&rtc->ops_lock); 48 if (err) 49 return -EBUSY; 50 51 if (!rtc->ops) 52 err = -ENODEV; 53 else if (!rtc->ops->set_time) 54 err = -EINVAL; 55 else 56 err = rtc->ops->set_time(rtc->dev.parent, tm); 57 58 mutex_unlock(&rtc->ops_lock); 59 return err; 60 } 61 EXPORT_SYMBOL_GPL(rtc_set_time); 62 63 int rtc_set_mmss(struct rtc_device *rtc, unsigned long secs) 64 { 65 int err; 66 67 err = mutex_lock_interruptible(&rtc->ops_lock); 68 if (err) 69 return -EBUSY; 70 71 if (!rtc->ops) 72 err = -ENODEV; 73 else if (rtc->ops->set_mmss) 74 err = rtc->ops->set_mmss(rtc->dev.parent, secs); 75 else if (rtc->ops->read_time && rtc->ops->set_time) { 76 struct rtc_time new, old; 77 78 err = rtc->ops->read_time(rtc->dev.parent, &old); 79 if (err == 0) { 80 rtc_time_to_tm(secs, &new); 81 82 /* 83 * avoid writing when we're going to change the day of 84 * the month. We will retry in the next minute. This 85 * basically means that if the RTC must not drift 86 * by more than 1 minute in 11 minutes. 87 */ 88 if (!((old.tm_hour == 23 && old.tm_min == 59) || 89 (new.tm_hour == 23 && new.tm_min == 59))) 90 err = rtc->ops->set_time(rtc->dev.parent, 91 &new); 92 } 93 } 94 else 95 err = -EINVAL; 96 97 mutex_unlock(&rtc->ops_lock); 98 99 return err; 100 } 101 EXPORT_SYMBOL_GPL(rtc_set_mmss); 102 103 static int rtc_read_alarm_internal(struct rtc_device *rtc, struct rtc_wkalrm *alarm) 104 { 105 int err; 106 107 err = mutex_lock_interruptible(&rtc->ops_lock); 108 if (err) 109 return -EBUSY; 110 111 if (rtc->ops == NULL) 112 err = -ENODEV; 113 else if (!rtc->ops->read_alarm) 114 err = -EINVAL; 115 else { 116 memset(alarm, 0, sizeof(struct rtc_wkalrm)); 117 err = rtc->ops->read_alarm(rtc->dev.parent, alarm); 118 } 119 120 mutex_unlock(&rtc->ops_lock); 121 return err; 122 } 123 124 int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) 125 { 126 int err; 127 struct rtc_time before, now; 128 int first_time = 1; 129 130 /* The lower level RTC driver may not be capable of filling 131 * in all fields of the rtc_time struct (eg. rtc-cmos), 132 * and so might instead return -1 in some fields. 133 * We deal with that here by grabbing a current RTC timestamp 134 * and using values from that for any missing (-1) values. 135 * 136 * But this can be racey, because some fields of the RTC timestamp 137 * may have wrapped in the interval since we read the RTC alarm, 138 * which would lead to us inserting inconsistent values in place 139 * of the -1 fields. 140 * 141 * Reading the alarm and timestamp in the reverse sequence 142 * would have the same race condition, and not solve the issue. 143 * 144 * So, we must first read the RTC timestamp, 145 * then read the RTC alarm value, 146 * and then read a second RTC timestamp. 147 * 148 * If any fields of the second timestamp have changed 149 * when compared with the first timestamp, then we know 150 * our timestamp may be inconsistent with that used by 151 * the low-level rtc_read_alarm_internal() function. 152 * 153 * So, when the two timestamps disagree, we just loop and do 154 * the process again to get a fully consistent set of values. 155 * 156 * This could all instead be done in the lower level driver, 157 * but since more than one lower level RTC implementation needs it, 158 * then it's probably best best to do it here instead of there.. 159 */ 160 161 /* Get the "before" timestamp */ 162 err = rtc_read_time(rtc, &before); 163 if (err < 0) 164 return err; 165 do { 166 if (!first_time) 167 memcpy(&before, &now, sizeof(struct rtc_time)); 168 first_time = 0; 169 170 /* get the RTC alarm values, which may be incomplete */ 171 err = rtc_read_alarm_internal(rtc, alarm); 172 if (err) 173 return err; 174 if (!alarm->enabled) 175 return 0; 176 177 /* get the "after" timestamp, to detect wrapped fields */ 178 err = rtc_read_time(rtc, &now); 179 if (err < 0) 180 return err; 181 182 /* note that tm_sec is a "don't care" value here: */ 183 } while ( before.tm_min != now.tm_min 184 || before.tm_hour != now.tm_hour 185 || before.tm_mon != now.tm_mon 186 || before.tm_year != now.tm_year 187 || before.tm_isdst != now.tm_isdst); 188 189 /* Fill in any missing alarm fields using the timestamp */ 190 if (alarm->time.tm_sec == -1) 191 alarm->time.tm_sec = now.tm_sec; 192 if (alarm->time.tm_min == -1) 193 alarm->time.tm_min = now.tm_min; 194 if (alarm->time.tm_hour == -1) 195 alarm->time.tm_hour = now.tm_hour; 196 if (alarm->time.tm_mday == -1) 197 alarm->time.tm_mday = now.tm_mday; 198 if (alarm->time.tm_mon == -1) 199 alarm->time.tm_mon = now.tm_mon; 200 if (alarm->time.tm_year == -1) 201 alarm->time.tm_year = now.tm_year; 202 return 0; 203 } 204 EXPORT_SYMBOL_GPL(rtc_read_alarm); 205 206 int rtc_set_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm) 207 { 208 int err; 209 210 err = rtc_valid_tm(&alarm->time); 211 if (err != 0) 212 return err; 213 214 err = mutex_lock_interruptible(&rtc->ops_lock); 215 if (err) 216 return -EBUSY; 217 218 if (!rtc->ops) 219 err = -ENODEV; 220 else if (!rtc->ops->set_alarm) 221 err = -EINVAL; 222 else 223 err = rtc->ops->set_alarm(rtc->dev.parent, alarm); 224 225 mutex_unlock(&rtc->ops_lock); 226 return err; 227 } 228 EXPORT_SYMBOL_GPL(rtc_set_alarm); 229 230 /** 231 * rtc_update_irq - report RTC periodic, alarm, and/or update irqs 232 * @rtc: the rtc device 233 * @num: how many irqs are being reported (usually one) 234 * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF 235 * Context: in_interrupt(), irqs blocked 236 */ 237 void rtc_update_irq(struct rtc_device *rtc, 238 unsigned long num, unsigned long events) 239 { 240 spin_lock(&rtc->irq_lock); 241 rtc->irq_data = (rtc->irq_data + (num << 8)) | events; 242 spin_unlock(&rtc->irq_lock); 243 244 spin_lock(&rtc->irq_task_lock); 245 if (rtc->irq_task) 246 rtc->irq_task->func(rtc->irq_task->private_data); 247 spin_unlock(&rtc->irq_task_lock); 248 249 wake_up_interruptible(&rtc->irq_queue); 250 kill_fasync(&rtc->async_queue, SIGIO, POLL_IN); 251 } 252 EXPORT_SYMBOL_GPL(rtc_update_irq); 253 254 struct rtc_device *rtc_class_open(char *name) 255 { 256 struct device *dev; 257 struct rtc_device *rtc = NULL; 258 259 down(&rtc_class->sem); 260 list_for_each_entry(dev, &rtc_class->devices, node) { 261 if (strncmp(dev->bus_id, name, BUS_ID_SIZE) == 0) { 262 dev = get_device(dev); 263 if (dev) 264 rtc = to_rtc_device(dev); 265 break; 266 } 267 } 268 269 if (rtc) { 270 if (!try_module_get(rtc->owner)) { 271 put_device(dev); 272 rtc = NULL; 273 } 274 } 275 up(&rtc_class->sem); 276 277 return rtc; 278 } 279 EXPORT_SYMBOL_GPL(rtc_class_open); 280 281 void rtc_class_close(struct rtc_device *rtc) 282 { 283 module_put(rtc->owner); 284 put_device(&rtc->dev); 285 } 286 EXPORT_SYMBOL_GPL(rtc_class_close); 287 288 int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task) 289 { 290 int retval = -EBUSY; 291 292 if (task == NULL || task->func == NULL) 293 return -EINVAL; 294 295 /* Cannot register while the char dev is in use */ 296 if (!(mutex_trylock(&rtc->char_lock))) 297 return -EBUSY; 298 299 spin_lock_irq(&rtc->irq_task_lock); 300 if (rtc->irq_task == NULL) { 301 rtc->irq_task = task; 302 retval = 0; 303 } 304 spin_unlock_irq(&rtc->irq_task_lock); 305 306 mutex_unlock(&rtc->char_lock); 307 308 return retval; 309 } 310 EXPORT_SYMBOL_GPL(rtc_irq_register); 311 312 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task) 313 { 314 spin_lock_irq(&rtc->irq_task_lock); 315 if (rtc->irq_task == task) 316 rtc->irq_task = NULL; 317 spin_unlock_irq(&rtc->irq_task_lock); 318 } 319 EXPORT_SYMBOL_GPL(rtc_irq_unregister); 320 321 /** 322 * rtc_irq_set_state - enable/disable 2^N Hz periodic IRQs 323 * @rtc: the rtc device 324 * @task: currently registered with rtc_irq_register() 325 * @enabled: true to enable periodic IRQs 326 * Context: any 327 * 328 * Note that rtc_irq_set_freq() should previously have been used to 329 * specify the desired frequency of periodic IRQ task->func() callbacks. 330 */ 331 int rtc_irq_set_state(struct rtc_device *rtc, struct rtc_task *task, int enabled) 332 { 333 int err = 0; 334 unsigned long flags; 335 336 if (rtc->ops->irq_set_state == NULL) 337 return -ENXIO; 338 339 spin_lock_irqsave(&rtc->irq_task_lock, flags); 340 if (rtc->irq_task != NULL && task == NULL) 341 err = -EBUSY; 342 if (rtc->irq_task != task) 343 err = -EACCES; 344 spin_unlock_irqrestore(&rtc->irq_task_lock, flags); 345 346 if (err == 0) 347 err = rtc->ops->irq_set_state(rtc->dev.parent, enabled); 348 349 return err; 350 } 351 EXPORT_SYMBOL_GPL(rtc_irq_set_state); 352 353 /** 354 * rtc_irq_set_freq - set 2^N Hz periodic IRQ frequency for IRQ 355 * @rtc: the rtc device 356 * @task: currently registered with rtc_irq_register() 357 * @freq: positive frequency with which task->func() will be called 358 * Context: any 359 * 360 * Note that rtc_irq_set_state() is used to enable or disable the 361 * periodic IRQs. 362 */ 363 int rtc_irq_set_freq(struct rtc_device *rtc, struct rtc_task *task, int freq) 364 { 365 int err = 0; 366 unsigned long flags; 367 368 if (rtc->ops->irq_set_freq == NULL) 369 return -ENXIO; 370 371 if (!is_power_of_2(freq)) 372 return -EINVAL; 373 374 spin_lock_irqsave(&rtc->irq_task_lock, flags); 375 if (rtc->irq_task != NULL && task == NULL) 376 err = -EBUSY; 377 if (rtc->irq_task != task) 378 err = -EACCES; 379 spin_unlock_irqrestore(&rtc->irq_task_lock, flags); 380 381 if (err == 0) { 382 err = rtc->ops->irq_set_freq(rtc->dev.parent, freq); 383 if (err == 0) 384 rtc->irq_freq = freq; 385 } 386 return err; 387 } 388 EXPORT_SYMBOL_GPL(rtc_irq_set_freq); 389