File: /usr/src/linux/drivers/sgi/char/ds1286.c
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/types.h>
30 #include <linux/errno.h>
31 #include <linux/miscdevice.h>
32 #include <linux/slab.h>
33 #include <linux/ioport.h>
34 #include <linux/fcntl.h>
35 #include <linux/init.h>
36 #include <linux/poll.h>
37 #include <linux/rtc.h>
38 #include <linux/spinlock.h>
39
40 #include <asm/ds1286.h>
41 #include <asm/io.h>
42 #include <asm/uaccess.h>
43 #include <asm/system.h>
44
45 #define DS1286_VERSION "1.0"
46
47 /*
48 * We sponge a minor off of the misc major. No need slurping
49 * up another valuable major dev number for this. If you add
50 * an ioctl, make sure you don't conflict with SPARC's RTC
51 * ioctls.
52 */
53
54 static DECLARE_WAIT_QUEUE_HEAD(ds1286_wait);
55
56 static ssize_t ds1286_read(struct file *file, char *buf,
57 size_t count, loff_t *ppos);
58
59 static int ds1286_ioctl(struct inode *inode, struct file *file,
60 unsigned int cmd, unsigned long arg);
61
62 static unsigned int ds1286_poll(struct file *file, poll_table *wait);
63
64 void get_rtc_time (struct rtc_time *rtc_tm);
65 void get_rtc_alm_time (struct rtc_time *alm_tm);
66
67 void set_rtc_irq_bit(unsigned char bit);
68 void clear_rtc_irq_bit(unsigned char bit);
69
70 static inline unsigned char ds1286_is_updating(void);
71
72 static spinlock_t ds1286_lock = SPIN_LOCK_UNLOCKED;
73
74 /*
75 * Bits in rtc_status. (7 bits of room for future expansion)
76 */
77
78 #define RTC_IS_OPEN 0x01 /* means /dev/rtc is in use */
79 #define RTC_TIMER_ON 0x02 /* missed irq timer active */
80
81 unsigned char ds1286_status; /* bitmapped status byte. */
82 unsigned long ds1286_freq; /* Current periodic IRQ rate */
83
84 unsigned char days_in_mo[] =
85 {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
86
87 /*
88 * Now all the various file operations that we export.
89 */
90
91 static ssize_t ds1286_read(struct file *file, char *buf,
92 size_t count, loff_t *ppos)
93 {
94 return -EIO;
95 }
96
97 static int ds1286_ioctl(struct inode *inode, struct file *file,
98 unsigned int cmd, unsigned long arg)
99 {
100
101 struct rtc_time wtime;
102
103 switch (cmd) {
104 case RTC_AIE_OFF: /* Mask alarm int. enab. bit */
105 {
106 unsigned int flags;
107 unsigned char val;
108
109 if (!capable(CAP_SYS_TIME))
110 return -EACCES;
111
112 spin_lock_irqsave(&ds1286_lock, flags);
113 val = CMOS_READ(RTC_CMD);
114 val |= RTC_TDM;
115 CMOS_WRITE(val, RTC_CMD);
116 spin_unlock_irqrestore(&ds1286_lock, flags);
117
118 return 0;
119 }
120 case RTC_AIE_ON: /* Allow alarm interrupts. */
121 {
122 unsigned int flags;
123 unsigned char val;
124
125 if (!capable(CAP_SYS_TIME))
126 return -EACCES;
127
128 spin_lock_irqsave(&ds1286_lock, flags);
129 val = CMOS_READ(RTC_CMD);
130 val &= ~RTC_TDM;
131 CMOS_WRITE(val, RTC_CMD);
132 spin_unlock_irqrestore(&ds1286_lock, flags);
133
134 return 0;
135 }
136 case RTC_WIE_OFF: /* Mask watchdog int. enab. bit */
137 {
138 unsigned int flags;
139 unsigned char val;
140
141 if (!capable(CAP_SYS_TIME))
142 return -EACCES;
143
144 spin_lock_irqsave(&ds1286_lock, flags);
145 val = CMOS_READ(RTC_CMD);
146 val |= RTC_WAM;
147 CMOS_WRITE(val, RTC_CMD);
148 spin_unlock_irqrestore(&ds1286_lock, flags);
149
150 return 0;
151 }
152 case RTC_WIE_ON: /* Allow watchdog interrupts. */
153 {
154 unsigned int flags;
155 unsigned char val;
156
157 if (!capable(CAP_SYS_TIME))
158 return -EACCES;
159
160 spin_lock_irqsave(&ds1286_lock, flags);
161 val = CMOS_READ(RTC_CMD);
162 val &= ~RTC_WAM;
163 CMOS_WRITE(val, RTC_CMD);
164 spin_unlock_irqrestore(&ds1286_lock, flags);
165
166 return 0;
167 }
168 case RTC_ALM_READ: /* Read the present alarm time */
169 {
170 /*
171 * This returns a struct rtc_time. Reading >= 0xc0
172 * means "don't care" or "match all". Only the tm_hour,
173 * tm_min, and tm_sec values are filled in.
174 */
175
176 get_rtc_alm_time(&wtime);
177 break;
178 }
179 case RTC_ALM_SET: /* Store a time into the alarm */
180 {
181 /*
182 * This expects a struct rtc_time. Writing 0xff means
183 * "don't care" or "match all". Only the tm_hour,
184 * tm_min and tm_sec are used.
185 */
186 unsigned char hrs, min, sec;
187 struct rtc_time alm_tm;
188
189 if (!capable(CAP_SYS_TIME))
190 return -EACCES;
191
192 if (copy_from_user(&alm_tm, (struct rtc_time*)arg,
193 sizeof(struct rtc_time)))
194 return -EFAULT;
195
196 hrs = alm_tm.tm_hour;
197 min = alm_tm.tm_min;
198
199 if (hrs >= 24)
200 hrs = 0xff;
201
202 if (min >= 60)
203 min = 0xff;
204
205 BIN_TO_BCD(sec);
206 BIN_TO_BCD(min);
207 BIN_TO_BCD(hrs);
208
209 spin_lock(&ds1286_lock);
210 CMOS_WRITE(hrs, RTC_HOURS_ALARM);
211 CMOS_WRITE(min, RTC_MINUTES_ALARM);
212 spin_unlock(&ds1286_lock);
213
214 return 0;
215 }
216 case RTC_RD_TIME: /* Read the time/date from RTC */
217 {
218 get_rtc_time(&wtime);
219 break;
220 }
221 case RTC_SET_TIME: /* Set the RTC */
222 {
223 struct rtc_time rtc_tm;
224 unsigned char mon, day, hrs, min, sec, leap_yr;
225 unsigned char save_control;
226 unsigned int yrs, flags;
227
228 if (!capable(CAP_SYS_TIME))
229 return -EACCES;
230
231 if (copy_from_user(&rtc_tm, (struct rtc_time*)arg,
232 sizeof(struct rtc_time)))
233 return -EFAULT;
234
235 yrs = rtc_tm.tm_year + 1900;
236 mon = rtc_tm.tm_mon + 1; /* tm_mon starts at zero */
237 day = rtc_tm.tm_mday;
238 hrs = rtc_tm.tm_hour;
239 min = rtc_tm.tm_min;
240 sec = rtc_tm.tm_sec;
241
242 if (yrs < 1970)
243 return -EINVAL;
244
245 leap_yr = ((!(yrs % 4) && (yrs % 100)) || !(yrs % 400));
246
247 if ((mon > 12) || (day == 0))
248 return -EINVAL;
249
250 if (day > (days_in_mo[mon] + ((mon == 2) && leap_yr)))
251 return -EINVAL;
252
253 if ((hrs >= 24) || (min >= 60) || (sec >= 60))
254 return -EINVAL;
255
256 if ((yrs -= 1940) > 255) /* They are unsigned */
257 return -EINVAL;
258
259 if (yrs >= 100)
260 yrs -= 100;
261
262 BIN_TO_BCD(sec);
263 BIN_TO_BCD(min);
264 BIN_TO_BCD(hrs);
265 BIN_TO_BCD(day);
266 BIN_TO_BCD(mon);
267 BIN_TO_BCD(yrs);
268
269 spin_lock_irqsave(&ds1286_lock, flags);
270 save_control = CMOS_READ(RTC_CMD);
271 CMOS_WRITE((save_control|RTC_TE), RTC_CMD);
272
273 CMOS_WRITE(yrs, RTC_YEAR);
274 CMOS_WRITE(mon, RTC_MONTH);
275 CMOS_WRITE(day, RTC_DATE);
276 CMOS_WRITE(hrs, RTC_HOURS);
277 CMOS_WRITE(min, RTC_MINUTES);
278 CMOS_WRITE(sec, RTC_SECONDS);
279 CMOS_WRITE(0, RTC_HUNDREDTH_SECOND);
280
281 CMOS_WRITE(save_control, RTC_CMD);
282 spin_unlock_irqrestore(&ds1286_lock, flags);
283
284 return 0;
285 }
286 default:
287 return -EINVAL;
288 }
289 return copy_to_user((void *)arg, &wtime, sizeof wtime) ? -EFAULT : 0;
290 }
291
292 /*
293 * We enforce only one user at a time here with the open/close.
294 * Also clear the previous interrupt data on an open, and clean
295 * up things on a close.
296 */
297
298 static int ds1286_open(struct inode *inode, struct file *file)
299 {
300 spin_lock_irq(&ds1286_lock);
301
302 if (ds1286_status & RTC_IS_OPEN)
303 goto out_busy;
304
305 ds1286_status |= RTC_IS_OPEN;
306
307 spin_lock_irq(&ds1286_lock);
308 return 0;
309
310 out_busy:
311 spin_lock_irq(&ds1286_lock);
312 return -EBUSY;
313 }
314
315 static int ds1286_release(struct inode *inode, struct file *file)
316 {
317 ds1286_status &= ~RTC_IS_OPEN;
318
319 return 0;
320 }
321
322 static unsigned int ds1286_poll(struct file *file, poll_table *wait)
323 {
324 poll_wait(file, &ds1286_wait, wait);
325
326 return 0;
327 }
328
329 /*
330 * The various file operations we support.
331 */
332
333 static struct file_operations ds1286_fops = {
334 llseek: no_llseek,
335 read: ds1286_read,
336 poll: ds1286_poll,
337 ioctl: ds1286_ioctl,
338 open: ds1286_open,
339 release: ds1286_release,
340 };
341
342 static struct miscdevice ds1286_dev=
343 {
344 RTC_MINOR,
345 "rtc",
346 &ds1286_fops
347 };
348
349 int __init ds1286_init(void)
350 {
351 printk(KERN_INFO "DS1286 Real Time Clock Driver v%s\n", DS1286_VERSION);
352 misc_register(&ds1286_dev);
353
354 return 0;
355 }
356
357 static char *days[] = {
358 "***", "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
359 };
360
361 /*
362 * Info exported via "/proc/rtc".
363 */
364 int get_ds1286_status(char *buf)
365 {
366 char *p, *s;
367 struct rtc_time tm;
368 unsigned char hundredth, month, cmd, amode;
369
370 p = buf;
371
372 get_rtc_time(&tm);
373 hundredth = CMOS_READ(RTC_HUNDREDTH_SECOND);
374 BCD_TO_BIN(hundredth);
375
376 p += sprintf(p,
377 "rtc_time\t: %02d:%02d:%02d.%02d\n"
378 "rtc_date\t: %04d-%02d-%02d\n",
379 tm.tm_hour, tm.tm_min, tm.tm_sec, hundredth,
380 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday);
381
382 /*
383 * We implicitly assume 24hr mode here. Alarm values >= 0xc0 will
384 * match any value for that particular field. Values that are
385 * greater than a valid time, but less than 0xc0 shouldn't appear.
386 */
387 get_rtc_alm_time(&tm);
388 p += sprintf(p, "alarm\t\t: %s ", days[tm.tm_wday]);
389 if (tm.tm_hour <= 24)
390 p += sprintf(p, "%02d:", tm.tm_hour);
391 else
392 p += sprintf(p, "**:");
393
394 if (tm.tm_min <= 59)
395 p += sprintf(p, "%02d\n", tm.tm_min);
396 else
397 p += sprintf(p, "**\n");
398
399 month = CMOS_READ(RTC_MONTH);
400 p += sprintf(p,
401 "oscillator\t: %s\n"
402 "square_wave\t: %s\n",
403 (month & RTC_EOSC) ? "disabled" : "enabled",
404 (month & RTC_ESQW) ? "disabled" : "enabled");
405
406 amode = ((CMOS_READ(RTC_MINUTES_ALARM) & 0x80) >> 5) |
407 ((CMOS_READ(RTC_HOURS_ALARM) & 0x80) >> 6) |
408 ((CMOS_READ(RTC_DAY_ALARM) & 0x80) >> 7);
409 if (amode == 7) s = "each minute";
410 else if (amode == 3) s = "minutes match";
411 else if (amode == 1) s = "hours and minutes match";
412 else if (amode == 0) s = "days, hours and minutes match";
413 else s = "invalid";
414 p += sprintf(p, "alarm_mode\t: %s\n", s);
415
416 cmd = CMOS_READ(RTC_CMD);
417 p += sprintf(p,
418 "alarm_enable\t: %s\n"
419 "wdog_alarm\t: %s\n"
420 "alarm_mask\t: %s\n"
421 "wdog_alarm_mask\t: %s\n"
422 "interrupt_mode\t: %s\n"
423 "INTB_mode\t: %s_active\n"
424 "interrupt_pins\t: %s\n",
425 (cmd & RTC_TDF) ? "yes" : "no",
426 (cmd & RTC_WAF) ? "yes" : "no",
427 (cmd & RTC_TDM) ? "disabled" : "enabled",
428 (cmd & RTC_WAM) ? "disabled" : "enabled",
429 (cmd & RTC_PU_LVL) ? "pulse" : "level",
430 (cmd & RTC_IBH_LO) ? "low" : "high",
431 (cmd & RTC_IPSW) ? "unswapped" : "swapped");
432
433 return p - buf;
434 }
435
436 /*
437 * Returns true if a clock update is in progress
438 */
439 static inline unsigned char ds1286_is_updating(void)
440 {
441 return CMOS_READ(RTC_CMD) & RTC_TE;
442 }
443
444 void get_rtc_time(struct rtc_time *rtc_tm)
445 {
446 unsigned long uip_watchdog = jiffies;
447 unsigned char save_control;
448 unsigned int flags;
449
450 /*
451 * read RTC once any update in progress is done. The update
452 * can take just over 2ms. We wait 10 to 20ms. There is no need to
453 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
454 * If you need to know *exactly* when a second has started, enable
455 * periodic update complete interrupts, (via ioctl) and then
456 * immediately read /dev/rtc which will block until you get the IRQ.
457 * Once the read clears, read the RTC time (again via ioctl). Easy.
458 */
459
460 if (ds1286_is_updating() != 0)
461 while (jiffies - uip_watchdog < 2*HZ/100)
462 barrier();
463
464 /*
465 * Only the values that we read from the RTC are set. We leave
466 * tm_wday, tm_yday and tm_isdst untouched. Even though the
467 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
468 * by the RTC when initially set to a non-zero value.
469 */
470 spin_lock_irqsave(&ds1286_lock, flags);
471 save_control = CMOS_READ(RTC_CMD);
472 CMOS_WRITE((save_control|RTC_TE), RTC_CMD);
473
474 rtc_tm->tm_sec = CMOS_READ(RTC_SECONDS);
475 rtc_tm->tm_min = CMOS_READ(RTC_MINUTES);
476 rtc_tm->tm_hour = CMOS_READ(RTC_HOURS) & 0x1f;
477 rtc_tm->tm_mday = CMOS_READ(RTC_DATE);
478 rtc_tm->tm_mon = CMOS_READ(RTC_MONTH) & 0x1f;
479 rtc_tm->tm_year = CMOS_READ(RTC_YEAR);
480
481 CMOS_WRITE(save_control, RTC_CMD);
482 spin_unlock_irqrestore(&ds1286_lock, flags);
483
484 BCD_TO_BIN(rtc_tm->tm_sec);
485 BCD_TO_BIN(rtc_tm->tm_min);
486 BCD_TO_BIN(rtc_tm->tm_hour);
487 BCD_TO_BIN(rtc_tm->tm_mday);
488 BCD_TO_BIN(rtc_tm->tm_mon);
489 BCD_TO_BIN(rtc_tm->tm_year);
490
491 /*
492 * Account for differences between how the RTC uses the values
493 * and how they are defined in a struct rtc_time;
494 */
495 if (rtc_tm->tm_year < 45)
496 rtc_tm->tm_year += 30;
497 if ((rtc_tm->tm_year += 40) < 70)
498 rtc_tm->tm_year += 100;
499
500 rtc_tm->tm_mon--;
501 }
502
503 void get_rtc_alm_time(struct rtc_time *alm_tm)
504 {
505 unsigned char cmd;
506 unsigned int flags;
507
508 /*
509 * Only the values that we read from the RTC are set. That
510 * means only tm_wday, tm_hour, tm_min.
511 */
512 spin_lock_irqsave(&ds1286_lock, flags);
513 alm_tm->tm_min = CMOS_READ(RTC_MINUTES_ALARM) & 0x7f;
514 alm_tm->tm_hour = CMOS_READ(RTC_HOURS_ALARM) & 0x1f;
515 alm_tm->tm_wday = CMOS_READ(RTC_DAY_ALARM) & 0x07;
516 cmd = CMOS_READ(RTC_CMD);
517 spin_unlock_irqrestore(&ds1286_lock, flags);
518
519 BCD_TO_BIN(alm_tm->tm_min);
520 BCD_TO_BIN(alm_tm->tm_hour);
521 alm_tm->tm_sec = 0;
522 }
523