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