1/* 2 * DS1286 Real Time Clock interface for Linux 3 * 4 * Copyright (C) 1998, 1999, 2000 Ralf Baechle 5 * 6 * Based on code written by Paul Gortmaker. 7 * 8 * This driver allows use of the real time clock (built into nearly all 9 * computers) from user space. It exports the /dev/rtc interface supporting 10 * various ioctl() and also the /proc/rtc pseudo-file for status 11 * information. 12 * 13 * The ioctls can be used to set the interrupt behaviour and generation rate 14 * from the RTC via IRQ 8. Then the /dev/rtc interface can be used to make 15 * use of these timer interrupts, be they interval or alarm based. 16 * 17 * The /dev/rtc interface will block on reads until an interrupt has been 18 * received. If a RTC interrupt has already happened, it will output an 19 * unsigned long and then block. The output value contains the interrupt 20 * status in the low byte and the number of interrupts since the last read 21 * in the remaining high bytes. The /dev/rtc interface can also be used with 22 * the select(2) call. 23 * 24 * This program is free software; you can redistribute it and/or modify it 25 * under the terms of the GNU General Public License as published by the 26 * Free Software Foundation; either version 2 of the License, or (at your 27 * option) any later version. 28 */ 29#include <linux/ds1286.h> 30#include <linux/types.h> 31#include <linux/errno.h> 32#include <linux/miscdevice.h> 33#include <linux/slab.h> 34#include <linux/ioport.h> 35#include <linux/fcntl.h> 36#include <linux/init.h> 37#include <linux/poll.h> 38#include <linux/rtc.h> 39#include <linux/spinlock.h> 40#include <linux/bcd.h> 41#include <linux/proc_fs.h> 42 43#include <asm/uaccess.h> 44#include <asm/system.h> 45 46#define DS1286_VERSION "1.0" 47 48/* 49 * We sponge a minor off of the misc major. No need slurping 50 * up another valuable major dev number for this. If you add 51 * an ioctl, make sure you don't conflict with SPARC's RTC 52 * ioctls. 53 */ 54 55static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait); 56 57static ssize_t ds1286_read(struct file *file, char *buf, 58 size_t count, loff_t *ppos); 59 60static int ds1286_ioctl(struct inode *inode, struct file *file, 61 unsigned int cmd, unsigned long arg); 62 63static unsigned int ds1286_poll(struct file *file, poll_table *wait); 64 65static void ds1286_get_alm_time (struct rtc_time *alm_tm); 66static void ds1286_get_time(struct rtc_time *rtc_tm); 67static int ds1286_set_time(struct rtc_time *rtc_tm); 68 69static inline unsigned char ds1286_is_updating(void); 70 71static DEFINE_SPINLOCK(ds1286_lock); 72 73static int ds1286_read_proc(char *page, char **start, off_t off, 74 int count, int *eof, void *data); 75 76/* 77 * Bits in rtc_status. (7 bits of room for future expansion) 78 */ 79 80#define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */ 81#define RTC_TIMER_ON 0x02 /* missed irq timer active */ 82 83static unsigned char ds1286_status; /* bitmapped status byte. */ 84 85static unsigned char days_in_mo[] = { 86 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 87}; 88 89/* 90 * Now all the various file operations that we export. 91 */ 92 93static ssize_t ds1286_read(struct file *file, char *buf, 94 size_t count, loff_t *ppos) 95{ 96 return -EIO; 97} 98 99static int ds1286_ioctl(struct inode *inode, struct file *file, 100 unsigned int cmd, unsigned long arg) 101{ 102 struct rtc_time wtime; 103 104 switch (cmd) { 105 case RTC_AIE_OFF: /* Mask alarm int. enab. bit */ 106 { 107 unsigned long flags; 108 unsigned char val; 109 110 if (!capable(CAP_SYS_TIME)) 111 return -EACCES; 112 113 spin_lock_irqsave(&ds1286_lock, flags); 114 val = rtc_read(RTC_CMD); 115 val |= RTC_TDM; 116 rtc_write(val, RTC_CMD); 117 spin_unlock_irqrestore(&ds1286_lock, flags); 118 119 return 0; 120 } 121 case RTC_AIE_ON: /* Allow alarm interrupts. */ 122 { 123 unsigned long flags; 124 unsigned char val; 125 126 if (!capable(CAP_SYS_TIME)) 127 return -EACCES; 128 129 spin_lock_irqsave(&ds1286_lock, flags); 130 val = rtc_read(RTC_CMD); 131 val &= ~RTC_TDM; 132 rtc_write(val, RTC_CMD); 133 spin_unlock_irqrestore(&ds1286_lock, flags); 134 135 return 0; 136 } 137 case RTC_WIE_OFF: /* Mask watchdog int. enab. bit */ 138 { 139 unsigned long flags; 140 unsigned char val; 141 142 if (!capable(CAP_SYS_TIME)) 143 return -EACCES; 144 145 spin_lock_irqsave(&ds1286_lock, flags); 146 val = rtc_read(RTC_CMD); 147 val |= RTC_WAM; 148 rtc_write(val, RTC_CMD); 149 spin_unlock_irqrestore(&ds1286_lock, flags); 150 151 return 0; 152 } 153 case RTC_WIE_ON: /* Allow watchdog interrupts. */ 154 { 155 unsigned long flags; 156 unsigned char val; 157 158 if (!capable(CAP_SYS_TIME)) 159 return -EACCES; 160 161 spin_lock_irqsave(&ds1286_lock, flags); 162 val = rtc_read(RTC_CMD); 163 val &= ~RTC_WAM; 164 rtc_write(val, RTC_CMD); 165 spin_unlock_irqrestore(&ds1286_lock, flags); 166 167 return 0; 168 } 169 case RTC_ALM_READ: /* Read the present alarm time */ 170 { 171 /* 172 * This returns a struct rtc_time. Reading >= 0xc0 173 * means "don't care" or "match all". Only the tm_hour, 174 * tm_min, and tm_sec values are filled in. 175 */ 176 177 memset(&wtime, 0, sizeof(wtime)); 178 ds1286_get_alm_time(&wtime); 179 break; 180 } 181 case RTC_ALM_SET: /* Store a time into the alarm */ 182 { 183 /* 184 * This expects a struct rtc_time. Writing 0xff means 185 * "don't care" or "match all". Only the tm_hour, 186 * tm_min and tm_sec are used. 187 */ 188 unsigned char hrs, min, sec; 189 struct rtc_time alm_tm; 190 191 if (!capable(CAP_SYS_TIME)) 192 return -EACCES; 193 194 if (copy_from_user(&alm_tm, (struct rtc_time*)arg, 195 sizeof(struct rtc_time))) 196 return -EFAULT; 197 198 hrs = alm_tm.tm_hour; 199 min = alm_tm.tm_min; 200 sec = alm_tm.tm_sec; 201 202 if (hrs >= 24) 203 hrs = 0xff; 204 205 if (min >= 60) 206 min = 0xff; 207 208 if (sec != 0) 209 return -EINVAL; 210 211 min = BIN2BCD(min); 212 min = BIN2BCD(hrs); 213 214 spin_lock(&ds1286_lock); 215 rtc_write(hrs, RTC_HOURS_ALARM); 216 rtc_write(min, RTC_MINUTES_ALARM); 217 spin_unlock(&ds1286_lock); 218 219 return 0; 220 } 221 case RTC_RD_TIME: /* Read the time/date from RTC */ 222 { 223 memset(&wtime, 0, sizeof(wtime)); 224 ds1286_get_time(&wtime); 225 break; 226 } 227 case RTC_SET_TIME: /* Set the RTC */ 228 { 229 struct rtc_time rtc_tm; 230 231 if (!capable(CAP_SYS_TIME)) 232 return -EACCES; 233 234 if (copy_from_user(&rtc_tm, (struct rtc_time*)arg, 235 sizeof(struct rtc_time))) 236 return -EFAULT; 237 238 return ds1286_set_time(&rtc_tm); 239 } 240 default: 241 return -EINVAL; 242 } 243 return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0; 244} 245 246/* 247 * We enforce only one user at a time here with the open/close. 248 * Also clear the previous interrupt data on an open, and clean 249 * up things on a close. 250 */ 251 252static int ds1286_open(struct inode *inode, struct file *file) 253{ 254 spin_lock_irq(&ds1286_lock); 255 256 if (ds1286_status & RTC_IS_OPEN) 257 goto out_busy; 258 259 ds1286_status |= RTC_IS_OPEN; 260 261 spin_unlock_irq(&ds1286_lock); 262 return 0; 263 264out_busy: 265 spin_lock_irq(&ds1286_lock); 266 return -EBUSY; 267} 268 269static int ds1286_release(struct inode *inode, struct file *file) 270{ 271 ds1286_status &= ~RTC_IS_OPEN; 272 273 return 0; 274} 275 276static unsigned int ds1286_poll(struct file *file, poll_table *wait) 277{ 278 poll_wait(file, &ds1286_wait, wait); 279 280 return 0; 281} 282 283/* 284 * The various file operations we support. 285 */ 286 287static const struct file_operations ds1286_fops = { 288 .llseek = no_llseek, 289 .read = ds1286_read, 290 .poll = ds1286_poll, 291 .ioctl = ds1286_ioctl, 292 .open = ds1286_open, 293 .release = ds1286_release, 294}; 295 296static struct miscdevice ds1286_dev= 297{ 298 .minor = RTC_MINOR, 299 .name = "rtc", 300 .fops = &ds1286_fops, 301}; 302 303static int __init ds1286_init(void) 304{ 305 int err; 306 307 printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION); 308 309 err = misc_register(&ds1286_dev); 310 if (err) 311 goto out; 312 313 if (!create_proc_read_entry("driver/rtc", 0, 0, ds1286_read_proc, NULL)) { 314 err = -ENOMEM; 315 316 goto out_deregister; 317 } 318 319 return 0; 320 321out_deregister: 322 misc_deregister(&ds1286_dev); 323 324out: 325 return err; 326} 327 328static void __exit ds1286_exit(void) 329{ 330 remove_proc_entry("driver/rtc", NULL); 331 misc_deregister(&ds1286_dev); 332} 333 334static char *days[] = { 335 "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" 336}; 337 338/* 339 * Info exported via "/proc/rtc". 340 */ 341static int ds1286_proc_output(char *buf) 342{ 343 char *p, *s; 344 struct rtc_time tm; 345 unsigned char hundredth, month, cmd, amode; 346 347 p = buf; 348 349 ds1286_get_time(&tm); 350 hundredth = rtc_read(RTC_HUNDREDTH_SECOND); 351 BCD_TO_BIN(hundredth); 352 353 p += sprintf(p, 354 "rtc_time\t: %02d:%02d:%02d.%02d\n" 355 "rtc_date\t: %04d-%02d-%02d\n", 356 tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth, 357 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday); 358 359 /* 360 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will 361 * match any value for that particular field. Values that are 362 * greater than a valid time, but less than 0xc0 shouldn't appear. 363 */ 364 ds1286_get_alm_time(&tm); 365 p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]); 366 if (tm.tm_hour <= 24) 367 p += sprintf(p, "%02d:", tm.tm_hour); 368 else 369 p += sprintf(p, "**:"); 370 371 if (tm.tm_min <= 59) 372 p += sprintf(p, "%02d\n", tm.tm_min); 373 else 374 p += sprintf(p, "**\n"); 375 376 month = rtc_read(RTC_MONTH); 377 p += sprintf(p, 378 "oscillator\t: %s\n" 379 "square_wave\t: %s\n", 380 (month & RTC_EOSC) ? "disabled" : "enabled", 381 (month & RTC_ESQW) ? "disabled" : "enabled"); 382 383 amode = ((rtc_read(RTC_MINUTES_ALARM) & 0x80) >> 5) | 384 ((rtc_read(RTC_HOURS_ALARM) & 0x80) >> 6) | 385 ((rtc_read(RTC_DAY_ALARM) & 0x80) >> 7); 386 if (amode == 7) s = "each minute"; 387 else if (amode == 3) s = "minutes match"; 388 else if (amode == 1) s = "hours and minutes match"; 389 else if (amode == 0) s = "days, hours and minutes match"; 390 else s = "invalid"; 391 p += sprintf(p, "alarm_mode\t: %s\n", s); 392 393 cmd = rtc_read(RTC_CMD); 394 p += sprintf(p, 395 "alarm_enable\t: %s\n" 396 "wdog_alarm\t: %s\n" 397 "alarm_mask\t: %s\n" 398 "wdog_alarm_mask\t: %s\n" 399 "interrupt_mode\t: %s\n" 400 "INTB_mode\t: %s_active\n" 401 "interrupt_pins\t: %s\n", 402 (cmd & RTC_TDF) ? "yes" : "no", 403 (cmd & RTC_WAF) ? "yes" : "no", 404 (cmd & RTC_TDM) ? "disabled" : "enabled", 405 (cmd & RTC_WAM) ? "disabled" : "enabled", 406 (cmd & RTC_PU_LVL) ? "pulse" : "level", 407 (cmd & RTC_IBH_LO) ? "low" : "high", 408 (cmd & RTC_IPSW) ? "unswapped" : "swapped"); 409 410 return p - buf; 411} 412 413static int ds1286_read_proc(char *page, char **start, off_t off, 414 int count, int *eof, void *data) 415{ 416 int len = ds1286_proc_output (page); 417 if (len <= off+count) *eof = 1; 418 *start = page + off; 419 len -= off; 420 if (len>count) 421 len = count; 422 if (len<0) 423 len = 0; 424 425 return len; 426} 427 428/* 429 * Returns true if a clock update is in progress 430 */ 431static inline unsigned char ds1286_is_updating(void) 432{ 433 return rtc_read(RTC_CMD) & RTC_TE; 434} 435 436 437static void ds1286_get_time(struct rtc_time *rtc_tm) 438{ 439 unsigned char save_control; 440 unsigned long flags; 441 unsigned long uip_watchdog = jiffies; 442 443 /* 444 * read RTC once any update in progress is done. The update 445 * can take just over 2ms. We wait 10 to 20ms. There is no need to 446 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP. 447 * If you need to know *exactly* when a second has started, enable 448 * periodic update complete interrupts, (via ioctl) and then 449 * immediately read /dev/rtc which will block until you get the IRQ. 450 * Once the read clears, read the RTC time (again via ioctl). Easy. 451 */ 452 453 if (ds1286_is_updating() != 0) 454 while (jiffies - uip_watchdog < 2*HZ/100) 455 barrier(); 456 457 /* 458 * Only the values that we read from the RTC are set. We leave 459 * tm_wday, tm_yday and tm_isdst untouched. Even though the 460 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated 461 * by the RTC when initially set to a non-zero value. 462 */ 463 spin_lock_irqsave(&ds1286_lock, flags); 464 save_control = rtc_read(RTC_CMD); 465 rtc_write((save_control|RTC_TE), RTC_CMD); 466 467 rtc_tm->tm_sec = rtc_read(RTC_SECONDS); 468 rtc_tm->tm_min = rtc_read(RTC_MINUTES); 469 rtc_tm->tm_hour = rtc_read(RTC_HOURS) & 0x3f; 470 rtc_tm->tm_mday = rtc_read(RTC_DATE); 471 rtc_tm->tm_mon = rtc_read(RTC_MONTH) & 0x1f; 472 rtc_tm->tm_year = rtc_read(RTC_YEAR); 473 474 rtc_write(save_control, RTC_CMD); 475 spin_unlock_irqrestore(&ds1286_lock, flags); 476 477 BCD_TO_BIN(rtc_tm->tm_sec); 478 BCD_TO_BIN(rtc_tm->tm_min); 479 BCD_TO_BIN(rtc_tm->tm_hour); 480 BCD_TO_BIN(rtc_tm->tm_mday); 481 BCD_TO_BIN(rtc_tm->tm_mon); 482 BCD_TO_BIN(rtc_tm->tm_year); 483 484 /* 485 * Account for differences between how the RTC uses the values 486 * and how they are defined in a struct rtc_time; 487 */ 488 if (rtc_tm->tm_year < 45) 489 rtc_tm->tm_year += 30; 490 if ((rtc_tm->tm_year += 40) < 70) 491 rtc_tm->tm_year += 100; 492 493 rtc_tm->tm_mon--; 494} 495 496static int ds1286_set_time(struct rtc_time *rtc_tm) 497{ 498 unsigned char mon, day, hrs, min, sec, leap_yr; 499 unsigned char save_control; 500 unsigned int yrs; 501 unsigned long flags; 502 503 504 yrs = rtc_tm->tm_year + 1900; 505 mon = rtc_tm->tm_mon + 1; /* tm_mon starts at zero */ 506 day = rtc_tm->tm_mday; 507 hrs = rtc_tm->tm_hour; 508 min = rtc_tm->tm_min; 509 sec = rtc_tm->tm_sec; 510 511 if (yrs < 1970) 512 return -EINVAL; 513 514 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400)); 515 516 if ((mon > 12) || (day == 0)) 517 return -EINVAL; 518 519 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr))) 520 return -EINVAL; 521 522 if ((hrs >= 24) || (min >= 60) || (sec >= 60)) 523 return -EINVAL; 524 525 if ((yrs -= 1940) > 255) /* They are unsigned */ 526 return -EINVAL; 527 528 if (yrs >= 100) 529 yrs -= 100; 530 531 BIN_TO_BCD(sec); 532 BIN_TO_BCD(min); 533 BIN_TO_BCD(hrs); 534 BIN_TO_BCD(day); 535 BIN_TO_BCD(mon); 536 BIN_TO_BCD(yrs); 537 538 spin_lock_irqsave(&ds1286_lock, flags); 539 save_control = rtc_read(RTC_CMD); 540 rtc_write((save_control|RTC_TE), RTC_CMD); 541 542 rtc_write(yrs, RTC_YEAR); 543 rtc_write(mon, RTC_MONTH); 544 rtc_write(day, RTC_DATE); 545 rtc_write(hrs, RTC_HOURS); 546 rtc_write(min, RTC_MINUTES); 547 rtc_write(sec, RTC_SECONDS); 548 rtc_write(0, RTC_HUNDREDTH_SECOND); 549 550 rtc_write(save_control, RTC_CMD); 551 spin_unlock_irqrestore(&ds1286_lock, flags); 552 553 return 0; 554} 555 556static void ds1286_get_alm_time(struct rtc_time *alm_tm) 557{ 558 unsigned char cmd; 559 unsigned long flags; 560 561 /* 562 * Only the values that we read from the RTC are set. That 563 * means only tm_wday, tm_hour, tm_min. 564 */ 565 spin_lock_irqsave(&ds1286_lock, flags); 566 alm_tm->tm_min = rtc_read(RTC_MINUTES_ALARM) & 0x7f; 567 alm_tm->tm_hour = rtc_read(RTC_HOURS_ALARM) & 0x1f; 568 alm_tm->tm_wday = rtc_read(RTC_DAY_ALARM) & 0x07; 569 cmd = rtc_read(RTC_CMD); 570 spin_unlock_irqrestore(&ds1286_lock, flags); 571 572 BCD_TO_BIN(alm_tm->tm_min); 573 BCD_TO_BIN(alm_tm->tm_hour); 574 alm_tm->tm_sec = 0; 575} 576 577module_init(ds1286_init); 578module_exit(ds1286_exit); 579 580MODULE_AUTHOR("Ralf Baechle"); 581MODULE_LICENSE("GPL"); 582MODULE_ALIAS_MISCDEV(RTC_MINOR); 583