drivers/char/genrtc.c

   1 /*
   2  *      Real Time Clock interface for
   3  *              - q40 and other m68k machines,
   4  *              - HP PARISC machines
   5  *              - PowerPC machines
   6  *      emulate some RTC irq capabilities in software
   7  *
   8  *      Copyright (C) 1999 Richard Zidlicky
   9  *
  10  *      based on Paul Gortmaker's rtc.c device and
  11  *           Sam Creasey Generic rtc driver
  12  *
  13  *      This driver allows use of the real time clock (built into
  14  *      nearly all computers) from user space. It exports the /dev/rtc
  15  *      interface supporting various ioctl() and also the /proc/dev/rtc
  16  *      pseudo-file for status information.
  17  *
  18  *      The ioctls can be used to set the interrupt behaviour where
  19  *      supported.
  20  *
  21  *      The /dev/rtc interface will block on reads until an interrupt
  22  *      has been received. If a RTC interrupt has already happened,
  23  *      it will output an unsigned long and then block. The output value
  24  *      contains the interrupt status in the low byte and the number of
  25  *      interrupts since the last read in the remaining high bytes. The
  26  *      /dev/rtc interface can also be used with the select(2) call.
  27  *
  28  *      This program is free software; you can redistribute it and/or
  29  *      modify it under the terms of the GNU General Public License
  30  *      as published by the Free Software Foundation; either version
  31  *      2 of the License, or (at your option) any later version.
  32  *
  33
  34  *      1.01 fix for 2.3.X                    rz@linux-m68k.org
  35  *      1.02 merged with code from genrtc.c   rz@linux-m68k.org
  36  *      1.03 make it more portable            zippel@linux-m68k.org
  37  *      1.04 removed useless timer code       rz@linux-m68k.org
  38  *      1.05 portable RTC_UIE emulation       rz@linux-m68k.org
  39  *      1.06 set_rtc_time can return an error trini@kernel.crashing.org
  40  *      1.07 ported to HP PARISC (hppa)       Helge Deller <deller@gmx.de>
  41  */
  42
  43 #define RTC_VERSION     "1.07"
  44
  45 #include <linux/module.h>
  46 #include <linux/errno.h>
  47 #include <linux/miscdevice.h>
  48 #include <linux/fcntl.h>
  49
  50 #include <linux/rtc.h>
  51 #include <linux/init.h>
  52 #include <linux/poll.h>
  53 #include <linux/proc_fs.h>
  54 #include <linux/workqueue.h>
  55
  56 #include <asm/uaccess.h>
  57 #include <asm/system.h>
  58 #include <asm/rtc.h>
  59
  60 /*
  61  *      We sponge a minor off of the misc major. No need slurping
  62  *      up another valuable major dev number for this. If you add
  63  *      an ioctl, make sure you don't conflict with SPARC's RTC
  64  *      ioctls.
  65  */
  66
  67 static DECLARE_WAIT_QUEUE_HEAD(gen_rtc_wait);
  68
  69 /*
  70  *      Bits in gen_rtc_status.
  71  */
  72
  73 #define RTC_IS_OPEN             0x01    /* means /dev/rtc is in use     */
  74
  75 static unsigned char gen_rtc_status;    /* bitmapped status byte.       */
  76 static unsigned long gen_rtc_irq_data;  /* our output to the world      */
  77
  78 /* months start at 0 now */
  79 static unsigned char days_in_mo[] =
  80 {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  81
  82 static int irq_active;
  83
  84 #ifdef CONFIG_GEN_RTC_X
  85 static struct work_struct genrtc_task;
  86 static struct timer_list timer_task;
  87
  88 static unsigned int oldsecs;
  89 static int lostint;
  90 static unsigned long tt_exp;
  91
  92 static void gen_rtc_timer(unsigned long data);
  93
  94 static volatile int stask_active;              /* schedule_work */
  95 static volatile int ttask_active;              /* timer_task */
  96 static int stop_rtc_timers;                    /* don't requeue tasks */
  97 static DEFINE_SPINLOCK(gen_rtc_lock);
  98
  99 static void gen_rtc_interrupt(unsigned long arg);
 100
 101 /*
 102  * Routine to poll RTC seconds field for change as often as possible,
 103  * after first RTC_UIE use timer to reduce polling
 104  */
 105 static void genrtc_troutine(void *data)
 106 {
 107         unsigned int tmp = get_rtc_ss();
 108
 109         if (stop_rtc_timers) {
 110                 stask_active = 0;
 111                 return;
 112         }
 113
 114         if (oldsecs != tmp){
 115                 oldsecs = tmp;
 116
 117                 timer_task.function = gen_rtc_timer;
 118                 timer_task.expires = jiffies + HZ - (HZ/10);
 119                 tt_exp=timer_task.expires;
 120                 ttask_active=1;
 121                 stask_active=0;
 122                 add_timer(&timer_task);
 123
 124                 gen_rtc_interrupt(0);
 125         } else if (schedule_work(&genrtc_task) == 0)
 126                 stask_active = 0;
 127 }
 128
 129 static void gen_rtc_timer(unsigned long data)
 130 {
 131         lostint = get_rtc_ss() - oldsecs ;
 132         if (lostint<0)
 133                 lostint = 60 - lostint;
 134         if (time_after(jiffies, tt_exp))
 135                 printk(KERN_INFO "genrtc: timer task delayed by %ld jiffies\n",
 136                        jiffies-tt_exp);
 137         ttask_active=0;
 138         stask_active=1;
 139         if ((schedule_work(&genrtc_task) == 0))
 140                 stask_active = 0;
 141 }
 142
 143 /*
 144  * call gen_rtc_interrupt function to signal an RTC_UIE,
 145  * arg is unused.
 146  * Could be invoked either from a real interrupt handler or
 147  * from some routine that periodically (eg 100HZ) monitors
 148  * whether RTC_SECS changed
 149  */
 150 static void gen_rtc_interrupt(unsigned long arg)
 151 {
 152         /*  We store the status in the low byte and the number of
 153          *      interrupts received since the last read in the remainder
 154          *      of rtc_irq_data.  */
 155
 156         gen_rtc_irq_data += 0x100;
 157         gen_rtc_irq_data &= ~0xff;
 158         gen_rtc_irq_data |= RTC_UIE;
 159
 160         if (lostint){
 161                 printk("genrtc: system delaying clock ticks?\n");
 162                 /* increment count so that userspace knows something is wrong */
 163                 gen_rtc_irq_data += ((lostint-1)<<8);
 164                 lostint = 0;
 165         }
 166
 167         wake_up_interruptible(&gen_rtc_wait);
 168 }
 169
 170 /*
 171  *      Now all the various file operations that we export.
 172  */
 173 static ssize_t gen_rtc_read(struct file *file, char __user *buf,
 174                         size_t count, loff_t *ppos)
 175 {
 176         DECLARE_WAITQUEUE(wait, current);
 177         unsigned long data;
 178         ssize_t retval;
 179
 180         if (count != sizeof (unsigned int) && count != sizeof (unsigned long))
 181                 return -EINVAL;
 182
 183         if (file->f_flags & O_NONBLOCK && !gen_rtc_irq_data)
 184                 return -EAGAIN;
 185
 186         add_wait_queue(&gen_rtc_wait, &wait);
 187         retval = -ERESTARTSYS;
 188
 189         while (1) {
 190                 set_current_state(TASK_INTERRUPTIBLE);
 191                 data = xchg(&gen_rtc_irq_data, 0);
 192                 if (data)
 193                         break;
 194                 if (signal_pending(current))
 195                         goto out;
 196                 schedule();
 197         }
 198
 199         /* first test allows optimizer to nuke this case for 32-bit machines */
 200         if (sizeof (int) != sizeof (long) && count == sizeof (unsigned int)) {
 201                 unsigned int uidata = data;
 202                 retval = put_user(uidata, (unsigned int __user *)buf) ?:
 203                         sizeof(unsigned int);
 204         }
 205         else {
 206                 retval = put_user(data, (unsigned long __user *)buf) ?:
 207                         sizeof(unsigned long);
 208         }
 209  out:
 210         current->state = TASK_RUNNING;
 211         remove_wait_queue(&gen_rtc_wait, &wait);
 212
 213         return retval;
 214 }
 215
 216 static unsigned int gen_rtc_poll(struct file *file,
 217                                  struct poll_table_struct *wait)
 218 {
 219         poll_wait(file, &gen_rtc_wait, wait);
 220         if (gen_rtc_irq_data != 0)
 221                 return POLLIN | POLLRDNORM;
 222         return 0;
 223 }
 224
 225 #endif
 226
 227 /*
 228  * Used to disable/enable interrupts, only RTC_UIE supported
 229  * We also clear out any old irq data after an ioctl() that
 230  * meddles with the interrupt enable/disable bits.
 231  */
 232
 233 static inline void gen_clear_rtc_irq_bit(unsigned char bit)
 234 {
 235 #ifdef CONFIG_GEN_RTC_X
 236         stop_rtc_timers = 1;
 237         if (ttask_active){
 238                 del_timer_sync(&timer_task);
 239                 ttask_active = 0;
 240         }
 241         while (stask_active)
 242                 schedule();
 243
 244         spin_lock(&gen_rtc_lock);
 245         irq_active = 0;
 246         spin_unlock(&gen_rtc_lock);
 247 #endif
 248 }
 249
 250 static inline int gen_set_rtc_irq_bit(unsigned char bit)
 251 {
 252 #ifdef CONFIG_GEN_RTC_X
 253         spin_lock(&gen_rtc_lock);
 254         if ( !irq_active ) {
 255                 irq_active = 1;
 256                 stop_rtc_timers = 0;
 257                 lostint = 0;
 258                 INIT_WORK(&genrtc_task, genrtc_troutine, NULL);
 259                 oldsecs = get_rtc_ss();
 260                 init_timer(&timer_task);
 261
 262                 stask_active = 1;
 263                 if (schedule_work(&genrtc_task) == 0){
 264                         stask_active = 0;
 265                 }
 266         }
 267         spin_unlock(&gen_rtc_lock);
 268         gen_rtc_irq_data = 0;
 269         return 0;
 270 #else
 271         return -EINVAL;
 272 #endif
 273 }
 274
 275 static int gen_rtc_ioctl(struct inode *inode, struct file *file,
 276                          unsigned int cmd, unsigned long arg)
 277 {
 278         struct rtc_time wtime;
 279         struct rtc_pll_info pll;
 280         void __user *argp = (void __user *)arg;
 281
 282         switch (cmd) {
 283
 284         case RTC_PLL_GET:
 285             if (get_rtc_pll(&pll))
 286                     return -EINVAL;
 287             else
 288                     return copy_to_user(argp, &pll, sizeof pll) ? -EFAULT : 0;
 289
 290         case RTC_PLL_SET:
 291                 if (!capable(CAP_SYS_TIME))
 292                         return -EACCES;
 293                 if (copy_from_user(&pll, argp, sizeof(pll)))
 294                         return -EFAULT;
 295             return set_rtc_pll(&pll);
 296
 297         case RTC_UIE_OFF:       /* disable ints from RTC updates.       */
 298                 gen_clear_rtc_irq_bit(RTC_UIE);
 299                 return 0;
 300
 301         case RTC_UIE_ON:        /* enable ints for RTC updates. */
 302                 return gen_set_rtc_irq_bit(RTC_UIE);
 303
 304         case RTC_RD_TIME:       /* Read the time/date from RTC  */
 305                 /* this doesn't get week-day, who cares */
 306                 memset(&wtime, 0, sizeof(wtime));
 307                 get_rtc_time(&wtime);
 308
 309                 return copy_to_user(argp, &wtime, sizeof(wtime)) ? -EFAULT : 0;
 310
 311         case RTC_SET_TIME:      /* Set the RTC */
 312             {
 313                 int year;
 314                 unsigned char leap_yr;
 315
 316                 if (!capable(CAP_SYS_TIME))
 317                         return -EACCES;
 318
 319                 if (copy_from_user(&wtime, argp, sizeof(wtime)))
 320                         return -EFAULT;
 321
 322                 year = wtime.tm_year + 1900;
 323                 leap_yr = ((!(year % 4) && (year % 100)) ||
 324                            !(year % 400));
 325
 326                 if ((wtime.tm_mon < 0 || wtime.tm_mon > 11) || (wtime.tm_mday < 1))
 327                         return -EINVAL;
 328
 329                 if (wtime.tm_mday < 0 || wtime.tm_mday >
 330                     (days_in_mo[wtime.tm_mon] + ((wtime.tm_mon == 1) && leap_yr)))
 331                         return -EINVAL;
 332
 333                 if (wtime.tm_hour < 0 || wtime.tm_hour >= 24 ||
 334                     wtime.tm_min < 0 || wtime.tm_min >= 60 ||
 335                     wtime.tm_sec < 0 || wtime.tm_sec >= 60)
 336                         return -EINVAL;
 337
 338                 return set_rtc_time(&wtime);
 339             }
 340         }
 341
 342         return -EINVAL;
 343 }
 344
 345 /*
 346  *      We enforce only one user at a time here with the open/close.
 347  *      Also clear the previous interrupt data on an open, and clean
 348  *      up things on a close.
 349  */
 350
 351 static int gen_rtc_open(struct inode *inode, struct file *file)
 352 {
 353         if (gen_rtc_status & RTC_IS_OPEN)
 354                 return -EBUSY;
 355
 356         gen_rtc_status |= RTC_IS_OPEN;
 357         gen_rtc_irq_data = 0;
 358         irq_active = 0;
 359
 360         return 0;
 361 }
 362
 363 static int gen_rtc_release(struct inode *inode, struct file *file)
 364 {
 365         /*
 366          * Turn off all interrupts once the device is no longer
 367          * in use and clear the data.
 368          */
 369
 370         gen_clear_rtc_irq_bit(RTC_PIE|RTC_AIE|RTC_UIE);
 371
 372         gen_rtc_status &= ~RTC_IS_OPEN;
 373         return 0;
 374 }
 375
 376
 377 #ifdef CONFIG_PROC_FS
 378
 379 /*
 380  *      Info exported via "/proc/rtc".
 381  */
 382
 383 static int gen_rtc_proc_output(char *buf)
 384 {
 385         char *p;
 386         struct rtc_time tm;
 387         unsigned int flags;
 388         struct rtc_pll_info pll;
 389
 390         p = buf;
 391
 392         flags = get_rtc_time(&tm);
 393
 394         p += sprintf(p,
 395                      "rtc_time\t: %02d:%02d:%02d\n"
 396                      "rtc_date\t: %04d-%02d-%02d\n"
 397                      "rtc_epoch\t: %04u\n",
 398                      tm.tm_hour, tm.tm_min, tm.tm_sec,
 399                      tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 1900);
 400
 401         tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
 402
 403         p += sprintf(p, "alarm\t\t: ");
 404         if (tm.tm_hour <= 24)
 405                 p += sprintf(p, "%02d:", tm.tm_hour);
 406         else
 407                 p += sprintf(p, "**:");
 408
 409         if (tm.tm_min <= 59)
 410                 p += sprintf(p, "%02d:", tm.tm_min);
 411         else
 412                 p += sprintf(p, "**:");
 413
 414         if (tm.tm_sec <= 59)
 415                 p += sprintf(p, "%02d\n", tm.tm_sec);
 416         else
 417                 p += sprintf(p, "**\n");
 418
 419         p += sprintf(p,
 420                      "DST_enable\t: %s\n"
 421                      "BCD\t\t: %s\n"
 422                      "24hr\t\t: %s\n"
 423                      "square_wave\t: %s\n"
 424                      "alarm_IRQ\t: %s\n"
 425                      "update_IRQ\t: %s\n"
 426                      "periodic_IRQ\t: %s\n"
 427                      "periodic_freq\t: %ld\n"
 428                      "batt_status\t: %s\n",
 429                      (flags & RTC_DST_EN) ? "yes" : "no",
 430                      (flags & RTC_DM_BINARY) ? "no" : "yes",
 431                      (flags & RTC_24H) ? "yes" : "no",
 432                      (flags & RTC_SQWE) ? "yes" : "no",
 433                      (flags & RTC_AIE) ? "yes" : "no",
 434                      irq_active ? "yes" : "no",
 435                      (flags & RTC_PIE) ? "yes" : "no",
 436                      0L /* freq */,
 437                      (flags & RTC_BATT_BAD) ? "bad" : "okay");
 438         if (!get_rtc_pll(&pll))
 439             p += sprintf(p,
 440                          "PLL adjustment\t: %d\n"
 441                          "PLL max +ve adjustment\t: %d\n"
 442                          "PLL max -ve adjustment\t: %d\n"
 443                          "PLL +ve adjustment factor\t: %d\n"
 444                          "PLL -ve adjustment factor\t: %d\n"
 445                          "PLL frequency\t: %ld\n",
 446                          pll.pll_value,
 447                          pll.pll_max,
 448                          pll.pll_min,
 449                          pll.pll_posmult,
 450                          pll.pll_negmult,
 451                          pll.pll_clock);
 452         return p - buf;
 453 }
 454
 455 static int gen_rtc_read_proc(char *page, char **start, off_t off,
 456                              int count, int *eof, void *data)
 457 {
 458         int len = gen_rtc_proc_output (page);
 459         if (len <= off+count) *eof = 1;
 460         *start = page + off;
 461         len -= off;
 462         if (len>count) len = count;
 463         if (len<0) len = 0;
 464         return len;
 465 }
 466
 467 static int __init gen_rtc_proc_init(void)
 468 {
 469         struct proc_dir_entry *r;
 470
 471         r = create_proc_read_entry("driver/rtc", 0, NULL, gen_rtc_read_proc, NULL);
 472         if (!r)
 473                 return -ENOMEM;
 474         return 0;
 475 }
 476 #else
 477 static inline int gen_rtc_proc_init(void) { return 0; }
 478 #endif /* CONFIG_PROC_FS */
 479
 480
 481 /*
 482  *      The various file operations we support.
 483  */
 484
 485 static const struct file_operations gen_rtc_fops = {
 486         .owner          = THIS_MODULE,
 487 #ifdef CONFIG_GEN_RTC_X
 488         .read           = gen_rtc_read,
 489         .poll           = gen_rtc_poll,
 490 #endif
 491         .ioctl          = gen_rtc_ioctl,
 492         .open           = gen_rtc_open,
 493         .release        = gen_rtc_release,
 494 };
 495
 496 static struct miscdevice rtc_gen_dev =
 497 {
 498         .minor          = RTC_MINOR,
 499         .name           = "rtc",
 500         .fops           = &gen_rtc_fops,
 501 };
 502
 503 static int __init rtc_generic_init(void)
 504 {
 505         int retval;
 506
 507         printk(KERN_INFO "Generic RTC Driver v%s\n", RTC_VERSION);
 508
 509         retval = misc_register(&rtc_gen_dev);
 510         if (retval < 0)
 511                 return retval;
 512
 513         retval = gen_rtc_proc_init();
 514         if (retval) {
 515                 misc_deregister(&rtc_gen_dev);
 516                 return retval;
 517         }
 518
 519         return 0;
 520 }
 521
 522 static void __exit rtc_generic_exit(void)
 523 {
 524         remove_proc_entry ("driver/rtc", NULL);
 525         misc_deregister(&rtc_gen_dev);
 526 }
 527
 528
 529 module_init(rtc_generic_init);
 530 module_exit(rtc_generic_exit);
 531
 532 MODULE_AUTHOR("Richard Zidlicky");
 533 MODULE_LICENSE("GPL");
 534 MODULE_ALIAS_MISCDEV(RTC_MINOR);