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/driver/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/sched.h>
  47 #include <linux/errno.h>
  48 #include <linux/miscdevice.h>
  49 #include <linux/fcntl.h>
  50
  51 #include <linux/rtc.h>
  52 #include <linux/init.h>
  53 #include <linux/poll.h>
  54 #include <linux/proc_fs.h>
  55 #include <linux/seq_file.h>
  56 #include <linux/mutex.h>
  57 #include <linux/workqueue.h>
  58
  59 #include <asm/uaccess.h>
  60 #include <asm/rtc.h>
  61
  62 /*
  63  *      We sponge a minor off of the misc major. No need slurping
  64  *      up another valuable major dev number for this. If you add
  65  *      an ioctl, make sure you don't conflict with SPARC's RTC
  66  *      ioctls.
  67  */
  68
  69 static DEFINE_MUTEX(gen_rtc_mutex);
  70 static DECLARE_WAIT_QUEUE_HEAD(gen_rtc_wait);
  71
  72 /*
  73  *      Bits in gen_rtc_status.
  74  */
  75
  76 #define RTC_IS_OPEN             0x01    /* means /dev/rtc is in use     */
  77
  78 static unsigned char gen_rtc_status;    /* bitmapped status byte.       */
  79 static unsigned long gen_rtc_irq_data;  /* our output to the world      */
  80
  81 /* months start at 0 now */
  82 static unsigned char days_in_mo[] =
  83 {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  84
  85 static int irq_active;
  86
  87 #ifdef CONFIG_GEN_RTC_X
  88 static struct work_struct genrtc_task;
  89 static struct timer_list timer_task;
  90
  91 static unsigned int oldsecs;
  92 static int lostint;
  93 static unsigned long tt_exp;
  94
  95 static void gen_rtc_timer(unsigned long data);
  96
  97 static volatile int stask_active;              /* schedule_work */
  98 static volatile int ttask_active;              /* timer_task */
  99 static int stop_rtc_timers;                    /* don't requeue tasks */
 100 static DEFINE_SPINLOCK(gen_rtc_lock);
 101
 102 static void gen_rtc_interrupt(unsigned long arg);
 103
 104 /*
 105  * Routine to poll RTC seconds field for change as often as possible,
 106  * after first RTC_UIE use timer to reduce polling
 107  */
 108 static void genrtc_troutine(struct work_struct *work)
 109 {
 110         unsigned int tmp = get_rtc_ss();
 111
 112         if (stop_rtc_timers) {
 113                 stask_active = 0;
 114                 return;
 115         }
 116
 117         if (oldsecs != tmp){
 118                 oldsecs = tmp;
 119
 120                 timer_task.function = gen_rtc_timer;
 121                 timer_task.expires = jiffies + HZ - (HZ/10);
 122                 tt_exp=timer_task.expires;
 123                 ttask_active=1;
 124                 stask_active=0;
 125                 add_timer(&timer_task);
 126
 127                 gen_rtc_interrupt(0);
 128         } else if (schedule_work(&genrtc_task) == 0)
 129                 stask_active = 0;
 130 }
 131
 132 static void gen_rtc_timer(unsigned long data)
 133 {
 134         lostint = get_rtc_ss() - oldsecs ;
 135         if (lostint<0)
 136                 lostint = 60 - lostint;
 137         if (time_after(jiffies, tt_exp))
 138                 printk(KERN_INFO "genrtc: timer task delayed by %ld jiffies\n",
 139                        jiffies-tt_exp);
 140         ttask_active=0;
 141         stask_active=1;
 142         if ((schedule_work(&genrtc_task) == 0))
 143                 stask_active = 0;
 144 }
 145
 146 /*
 147  * call gen_rtc_interrupt function to signal an RTC_UIE,
 148  * arg is unused.
 149  * Could be invoked either from a real interrupt handler or
 150  * from some routine that periodically (eg 100HZ) monitors
 151  * whether RTC_SECS changed
 152  */
 153 static void gen_rtc_interrupt(unsigned long arg)
 154 {
 155         /*  We store the status in the low byte and the number of
 156          *      interrupts received since the last read in the remainder
 157          *      of rtc_irq_data.  */
 158
 159         gen_rtc_irq_data += 0x100;
 160         gen_rtc_irq_data &= ~0xff;
 161         gen_rtc_irq_data |= RTC_UIE;
 162
 163         if (lostint){
 164                 printk("genrtc: system delaying clock ticks?\n");
 165                 /* increment count so that userspace knows something is wrong */
 166                 gen_rtc_irq_data += ((lostint-1)<<8);
 167                 lostint = 0;
 168         }
 169
 170         wake_up_interruptible(&gen_rtc_wait);
 171 }
 172
 173 /*
 174  *      Now all the various file operations that we export.
 175  */
 176 static ssize_t gen_rtc_read(struct file *file, char __user *buf,
 177                         size_t count, loff_t *ppos)
 178 {
 179         unsigned long data;
 180         ssize_t retval;
 181
 182         if (count != sizeof (unsigned int) && count != sizeof (unsigned long))
 183                 return -EINVAL;
 184
 185         if (file->f_flags & O_NONBLOCK && !gen_rtc_irq_data)
 186                 return -EAGAIN;
 187
 188         retval = wait_event_interruptible(gen_rtc_wait,
 189                         (data = xchg(&gen_rtc_irq_data, 0)));
 190         if (retval)
 191                 goto out;
 192
 193         /* first test allows optimizer to nuke this case for 32-bit machines */
 194         if (sizeof (int) != sizeof (long) && count == sizeof (unsigned int)) {
 195                 unsigned int uidata = data;
 196                 retval = put_user(uidata, (unsigned int __user *)buf) ?:
 197                         sizeof(unsigned int);
 198         }
 199         else {
 200                 retval = put_user(data, (unsigned long __user *)buf) ?:
 201                         sizeof(unsigned long);
 202         }
 203 out:
 204         return retval;
 205 }
 206
 207 static unsigned int gen_rtc_poll(struct file *file,
 208                                  struct poll_table_struct *wait)
 209 {
 210         poll_wait(file, &gen_rtc_wait, wait);
 211         if (gen_rtc_irq_data != 0)
 212                 return POLLIN | POLLRDNORM;
 213         return 0;
 214 }
 215
 216 #endif
 217
 218 /*
 219  * Used to disable/enable interrupts, only RTC_UIE supported
 220  * We also clear out any old irq data after an ioctl() that
 221  * meddles with the interrupt enable/disable bits.
 222  */
 223
 224 static inline void gen_clear_rtc_irq_bit(unsigned char bit)
 225 {
 226 #ifdef CONFIG_GEN_RTC_X
 227         stop_rtc_timers = 1;
 228         if (ttask_active){
 229                 del_timer_sync(&timer_task);
 230                 ttask_active = 0;
 231         }
 232         while (stask_active)
 233                 schedule();
 234
 235         spin_lock(&gen_rtc_lock);
 236         irq_active = 0;
 237         spin_unlock(&gen_rtc_lock);
 238 #endif
 239 }
 240
 241 static inline int gen_set_rtc_irq_bit(unsigned char bit)
 242 {
 243 #ifdef CONFIG_GEN_RTC_X
 244         spin_lock(&gen_rtc_lock);
 245         if ( !irq_active ) {
 246                 irq_active = 1;
 247                 stop_rtc_timers = 0;
 248                 lostint = 0;
 249                 INIT_WORK(&genrtc_task, genrtc_troutine);
 250                 oldsecs = get_rtc_ss();
 251                 init_timer(&timer_task);
 252
 253                 stask_active = 1;
 254                 if (schedule_work(&genrtc_task) == 0){
 255                         stask_active = 0;
 256                 }
 257         }
 258         spin_unlock(&gen_rtc_lock);
 259         gen_rtc_irq_data = 0;
 260         return 0;
 261 #else
 262         return -EINVAL;
 263 #endif
 264 }
 265
 266 static int gen_rtc_ioctl(struct file *file,
 267                          unsigned int cmd, unsigned long arg)
 268 {
 269         struct rtc_time wtime;
 270         struct rtc_pll_info pll;
 271         void __user *argp = (void __user *)arg;
 272
 273         switch (cmd) {
 274
 275         case RTC_PLL_GET:
 276             memset(&pll, 0, sizeof(pll));
 277             if (get_rtc_pll(&pll))
 278                     return -EINVAL;
 279             else
 280                     return copy_to_user(argp, &pll, sizeof pll) ? -EFAULT : 0;
 281
 282         case RTC_PLL_SET:
 283                 if (!capable(CAP_SYS_TIME))
 284                         return -EACCES;
 285                 if (copy_from_user(&pll, argp, sizeof(pll)))
 286                         return -EFAULT;
 287             return set_rtc_pll(&pll);
 288
 289         case RTC_UIE_OFF:       /* disable ints from RTC updates.       */
 290                 gen_clear_rtc_irq_bit(RTC_UIE);
 291                 return 0;
 292
 293         case RTC_UIE_ON:        /* enable ints for RTC updates. */
 294                 return gen_set_rtc_irq_bit(RTC_UIE);
 295
 296         case RTC_RD_TIME:       /* Read the time/date from RTC  */
 297                 /* this doesn't get week-day, who cares */
 298                 memset(&wtime, 0, sizeof(wtime));
 299                 get_rtc_time(&wtime);
 300
 301                 return copy_to_user(argp, &wtime, sizeof(wtime)) ? -EFAULT : 0;
 302
 303         case RTC_SET_TIME:      /* Set the RTC */
 304             {
 305                 int year;
 306                 unsigned char leap_yr;
 307
 308                 if (!capable(CAP_SYS_TIME))
 309                         return -EACCES;
 310
 311                 if (copy_from_user(&wtime, argp, sizeof(wtime)))
 312                         return -EFAULT;
 313
 314                 year = wtime.tm_year + 1900;
 315                 leap_yr = ((!(year % 4) && (year % 100)) ||
 316                            !(year % 400));
 317
 318                 if ((wtime.tm_mon < 0 || wtime.tm_mon > 11) || (wtime.tm_mday < 1))
 319                         return -EINVAL;
 320
 321                 if (wtime.tm_mday < 0 || wtime.tm_mday >
 322                     (days_in_mo[wtime.tm_mon] + ((wtime.tm_mon == 1) && leap_yr)))
 323                         return -EINVAL;
 324
 325                 if (wtime.tm_hour < 0 || wtime.tm_hour >= 24 ||
 326                     wtime.tm_min < 0 || wtime.tm_min >= 60 ||
 327                     wtime.tm_sec < 0 || wtime.tm_sec >= 60)
 328                         return -EINVAL;
 329
 330                 return set_rtc_time(&wtime);
 331             }
 332         }
 333
 334         return -EINVAL;
 335 }
 336
 337 static long gen_rtc_unlocked_ioctl(struct file *file, unsigned int cmd,
 338                                    unsigned long arg)
 339 {
 340         int ret;
 341
 342         mutex_lock(&gen_rtc_mutex);
 343         ret = gen_rtc_ioctl(file, cmd, arg);
 344         mutex_unlock(&gen_rtc_mutex);
 345
 346         return ret;
 347 }
 348
 349 /*
 350  *      We enforce only one user at a time here with the open/close.
 351  *      Also clear the previous interrupt data on an open, and clean
 352  *      up things on a close.
 353  */
 354
 355 static int gen_rtc_open(struct inode *inode, struct file *file)
 356 {
 357         mutex_lock(&gen_rtc_mutex);
 358         if (gen_rtc_status & RTC_IS_OPEN) {
 359                 mutex_unlock(&gen_rtc_mutex);
 360                 return -EBUSY;
 361         }
 362
 363         gen_rtc_status |= RTC_IS_OPEN;
 364         gen_rtc_irq_data = 0;
 365         irq_active = 0;
 366         mutex_unlock(&gen_rtc_mutex);
 367
 368         return 0;
 369 }
 370
 371 static int gen_rtc_release(struct inode *inode, struct file *file)
 372 {
 373         /*
 374          * Turn off all interrupts once the device is no longer
 375          * in use and clear the data.
 376          */
 377
 378         gen_clear_rtc_irq_bit(RTC_PIE|RTC_AIE|RTC_UIE);
 379
 380         gen_rtc_status &= ~RTC_IS_OPEN;
 381         return 0;
 382 }
 383
 384
 385 #ifdef CONFIG_PROC_FS
 386
 387 /*
 388  *      Info exported via "/proc/driver/rtc".
 389  */
 390
 391 static int gen_rtc_proc_show(struct seq_file *m, void *v)
 392 {
 393         struct rtc_time tm;
 394         unsigned int flags;
 395         struct rtc_pll_info pll;
 396
 397         flags = get_rtc_time(&tm);
 398
 399         seq_printf(m,
 400                      "rtc_time\t: %02d:%02d:%02d\n"
 401                      "rtc_date\t: %04d-%02d-%02d\n"
 402                      "rtc_epoch\t: %04u\n",
 403                      tm.tm_hour, tm.tm_min, tm.tm_sec,
 404                      tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, 1900);
 405
 406         tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
 407
 408         seq_puts(m, "alarm\t\t: ");
 409         if (tm.tm_hour <= 24)
 410                 seq_printf(m, "%02d:", tm.tm_hour);
 411         else
 412                 seq_puts(m, "**:");
 413
 414         if (tm.tm_min <= 59)
 415                 seq_printf(m, "%02d:", tm.tm_min);
 416         else
 417                 seq_puts(m, "**:");
 418
 419         if (tm.tm_sec <= 59)
 420                 seq_printf(m, "%02d\n", tm.tm_sec);
 421         else
 422                 seq_puts(m, "**\n");
 423
 424         seq_printf(m,
 425                      "DST_enable\t: %s\n"
 426                      "BCD\t\t: %s\n"
 427                      "24hr\t\t: %s\n"
 428                      "square_wave\t: %s\n"
 429                      "alarm_IRQ\t: %s\n"
 430                      "update_IRQ\t: %s\n"
 431                      "periodic_IRQ\t: %s\n"
 432                      "periodic_freq\t: %ld\n"
 433                      "batt_status\t: %s\n",
 434                      (flags & RTC_DST_EN) ? "yes" : "no",
 435                      (flags & RTC_DM_BINARY) ? "no" : "yes",
 436                      (flags & RTC_24H) ? "yes" : "no",
 437                      (flags & RTC_SQWE) ? "yes" : "no",
 438                      (flags & RTC_AIE) ? "yes" : "no",
 439                      irq_active ? "yes" : "no",
 440                      (flags & RTC_PIE) ? "yes" : "no",
 441                      0L /* freq */,
 442                      (flags & RTC_BATT_BAD) ? "bad" : "okay");
 443         if (!get_rtc_pll(&pll))
 444             seq_printf(m,
 445                          "PLL adjustment\t: %d\n"
 446                          "PLL max +ve adjustment\t: %d\n"
 447                          "PLL max -ve adjustment\t: %d\n"
 448                          "PLL +ve adjustment factor\t: %d\n"
 449                          "PLL -ve adjustment factor\t: %d\n"
 450                          "PLL frequency\t: %ld\n",
 451                          pll.pll_value,
 452                          pll.pll_max,
 453                          pll.pll_min,
 454                          pll.pll_posmult,
 455                          pll.pll_negmult,
 456                          pll.pll_clock);
 457         return 0;
 458 }
 459
 460 static int gen_rtc_proc_open(struct inode *inode, struct file *file)
 461 {
 462         return single_open(file, gen_rtc_proc_show, NULL);
 463 }
 464
 465 static const struct file_operations gen_rtc_proc_fops = {
 466         .open           = gen_rtc_proc_open,
 467         .read           = seq_read,
 468         .llseek         = seq_lseek,
 469         .release        = single_release,
 470 };
 471
 472 static int __init gen_rtc_proc_init(void)
 473 {
 474         struct proc_dir_entry *r;
 475
 476         r = proc_create("driver/rtc", 0, NULL, &gen_rtc_proc_fops);
 477         if (!r)
 478                 return -ENOMEM;
 479         return 0;
 480 }
 481 #else
 482 static inline int gen_rtc_proc_init(void) { return 0; }
 483 #endif /* CONFIG_PROC_FS */
 484
 485
 486 /*
 487  *      The various file operations we support.
 488  */
 489
 490 static const struct file_operations gen_rtc_fops = {
 491         .owner          = THIS_MODULE,
 492 #ifdef CONFIG_GEN_RTC_X
 493         .read           = gen_rtc_read,
 494         .poll           = gen_rtc_poll,
 495 #endif
 496         .unlocked_ioctl = gen_rtc_unlocked_ioctl,
 497         .open           = gen_rtc_open,
 498         .release        = gen_rtc_release,
 499         .llseek         = noop_llseek,
 500 };
 501
 502 static struct miscdevice rtc_gen_dev =
 503 {
 504         .minor          = RTC_MINOR,
 505         .name           = "rtc",
 506         .fops           = &gen_rtc_fops,
 507 };
 508
 509 static int __init rtc_generic_init(void)
 510 {
 511         int retval;
 512
 513         printk(KERN_INFO "Generic RTC Driver v%s\n", RTC_VERSION);
 514
 515         retval = misc_register(&rtc_gen_dev);
 516         if (retval < 0)
 517                 return retval;
 518
 519         retval = gen_rtc_proc_init();
 520         if (retval) {
 521                 misc_deregister(&rtc_gen_dev);
 522                 return retval;
 523         }
 524
 525         return 0;
 526 }
 527
 528 static void __exit rtc_generic_exit(void)
 529 {
 530         remove_proc_entry ("driver/rtc", NULL);
 531         misc_deregister(&rtc_gen_dev);
 532 }
 533
 534
 535 module_init(rtc_generic_init);
 536 module_exit(rtc_generic_exit);
 537
 538 MODULE_AUTHOR("Richard Zidlicky");
 539 MODULE_LICENSE("GPL");
 540 MODULE_ALIAS_MISCDEV(RTC_MINOR);