drivers/char/efirtc.c

   1 /*
   2  * EFI Time Services Driver for Linux
   3  *
   4  * Copyright (C) 1999 Hewlett-Packard Co
   5  * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
   6  *
   7  * Based on skeleton from the drivers/char/rtc.c driver by P. Gortmaker
   8  *
   9  * This code provides an architected & portable interface to the real time
  10  * clock by using EFI instead of direct bit fiddling. The functionalities are
  11  * quite different from the rtc.c driver. The only way to talk to the device
  12  * is by using ioctl(). There is a /proc interface which provides the raw
  13  * information.
  14  *
  15  * Please note that we have kept the API as close as possible to the
  16  * legacy RTC. The standard /sbin/hwclock program should work normally
  17  * when used to get/set the time.
  18  *
  19  * NOTES:
  20  *      - Locking is required for safe execution of EFI calls with regards
  21  *        to interrupts and SMP.
  22  *
  23  * TODO (December 1999):
  24  *      - provide the API to set/get the WakeUp Alarm (different from the
  25  *        rtc.c alarm).
  26  *      - SMP testing
  27  *      - Add module support
  28  */
  29
  30
  31 #include <linux/types.h>
  32 #include <linux/errno.h>
  33 #include <linux/miscdevice.h>
  34 #include <linux/module.h>
  35 #include <linux/init.h>
  36 #include <linux/rtc.h>
  37 #include <linux/proc_fs.h>
  38 #include <linux/efi.h>
  39
  40 #include <asm/uaccess.h>
  41 #include <asm/system.h>
  42
  43 #define EFI_RTC_VERSION         "0.4"
  44
  45 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
  46 /*
  47  * EFI Epoch is 1/1/1998
  48  */
  49 #define EFI_RTC_EPOCH           1998
  50
  51 static DEFINE_SPINLOCK(efi_rtc_lock);
  52
  53 static int efi_rtc_ioctl(struct inode *inode, struct file *file,
  54                      unsigned int cmd, unsigned long arg);
  55
  56 #define is_leap(year) \
  57           ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
  58
  59 static const unsigned short int __mon_yday[2][13] =
  60 {
  61         /* Normal years.  */
  62         { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
  63         /* Leap years.  */
  64         { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
  65 };
  66
  67 /*
  68  * returns day of the year [0-365]
  69  */
  70 static inline int
  71 compute_yday(efi_time_t *eft)
  72 {
  73         /* efi_time_t.month is in the [1-12] so, we need -1 */
  74         return  __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
  75 }
  76 /*
  77  * returns day of the week [0-6] 0=Sunday
  78  *
  79  * Don't try to provide a year that's before 1998, please !
  80  */
  81 static int
  82 compute_wday(efi_time_t *eft)
  83 {
  84         int y;
  85         int ndays = 0;
  86
  87         if ( eft->year < 1998 ) {
  88                 printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
  89                 return -1;
  90         }
  91
  92         for(y=EFI_RTC_EPOCH; y < eft->year; y++ ) {
  93                 ndays += 365 + (is_leap(y) ? 1 : 0);
  94         }
  95         ndays += compute_yday(eft);
  96
  97         /*
  98          * 4=1/1/1998 was a Thursday
  99          */
 100         return (ndays + 4) % 7;
 101 }
 102
 103 static void
 104 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
 105 {
 106
 107         eft->year       = wtime->tm_year + 1900;
 108         eft->month      = wtime->tm_mon + 1;
 109         eft->day        = wtime->tm_mday;
 110         eft->hour       = wtime->tm_hour;
 111         eft->minute     = wtime->tm_min;
 112         eft->second     = wtime->tm_sec;
 113         eft->nanosecond = 0;
 114         eft->daylight   = wtime->tm_isdst ? EFI_ISDST: 0;
 115         eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
 116 }
 117
 118 static void
 119 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
 120 {
 121         memset(wtime, 0, sizeof(*wtime));
 122         wtime->tm_sec  = eft->second;
 123         wtime->tm_min  = eft->minute;
 124         wtime->tm_hour = eft->hour;
 125         wtime->tm_mday = eft->day;
 126         wtime->tm_mon  = eft->month - 1;
 127         wtime->tm_year = eft->year - 1900;
 128
 129         /* day of the week [0-6], Sunday=0 */
 130         wtime->tm_wday = compute_wday(eft);
 131
 132         /* day in the year [1-365]*/
 133         wtime->tm_yday = compute_yday(eft);
 134
 135
 136         switch (eft->daylight & EFI_ISDST) {
 137                 case EFI_ISDST:
 138                         wtime->tm_isdst = 1;
 139                         break;
 140                 case EFI_TIME_ADJUST_DAYLIGHT:
 141                         wtime->tm_isdst = 0;
 142                         break;
 143                 default:
 144                         wtime->tm_isdst = -1;
 145         }
 146 }
 147
 148 static int
 149 efi_rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 150                      unsigned long arg)
 151 {
 152
 153         efi_status_t    status;
 154         unsigned long   flags;
 155         efi_time_t      eft;
 156         efi_time_cap_t  cap;
 157         struct rtc_time wtime;
 158         struct rtc_wkalrm __user *ewp;
 159         unsigned char   enabled, pending;
 160
 161         switch (cmd) {
 162                 case RTC_UIE_ON:
 163                 case RTC_UIE_OFF:
 164                 case RTC_PIE_ON:
 165                 case RTC_PIE_OFF:
 166                 case RTC_AIE_ON:
 167                 case RTC_AIE_OFF:
 168                 case RTC_ALM_SET:
 169                 case RTC_ALM_READ:
 170                 case RTC_IRQP_READ:
 171                 case RTC_IRQP_SET:
 172                 case RTC_EPOCH_READ:
 173                 case RTC_EPOCH_SET:
 174                         return -EINVAL;
 175
 176                 case RTC_RD_TIME:
 177
 178                         spin_lock_irqsave(&efi_rtc_lock, flags);
 179
 180                         status = efi.get_time(&eft, &cap);
 181
 182                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 183
 184                         if (status != EFI_SUCCESS) {
 185                                 /* should never happen */
 186                                 printk(KERN_ERR "efitime: can't read time\n");
 187                                 return -EINVAL;
 188                         }
 189
 190                         convert_from_efi_time(&eft, &wtime);
 191
 192                         return copy_to_user((void __user *)arg, &wtime,
 193                                             sizeof (struct rtc_time)) ? - EFAULT : 0;
 194
 195                 case RTC_SET_TIME:
 196
 197                         if (!capable(CAP_SYS_TIME)) return -EACCES;
 198
 199                         if (copy_from_user(&wtime, (struct rtc_time __user *)arg,
 200                                            sizeof(struct rtc_time)) )
 201                                 return -EFAULT;
 202
 203                         convert_to_efi_time(&wtime, &eft);
 204
 205                         spin_lock_irqsave(&efi_rtc_lock, flags);
 206
 207                         status = efi.set_time(&eft);
 208
 209                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 210
 211                         return status == EFI_SUCCESS ? 0 : -EINVAL;
 212
 213                 case RTC_WKALM_SET:
 214
 215                         if (!capable(CAP_SYS_TIME)) return -EACCES;
 216
 217                         ewp = (struct rtc_wkalrm __user *)arg;
 218
 219                         if (  get_user(enabled, &ewp->enabled)
 220                            || copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
 221                                 return -EFAULT;
 222
 223                         convert_to_efi_time(&wtime, &eft);
 224
 225                         spin_lock_irqsave(&efi_rtc_lock, flags);
 226                         /*
 227                          * XXX Fixme:
 228                          * As of EFI 0.92 with the firmware I have on my
 229                          * machine this call does not seem to work quite
 230                          * right
 231                          */
 232                         status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);
 233
 234                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 235
 236                         return status == EFI_SUCCESS ? 0 : -EINVAL;
 237
 238                 case RTC_WKALM_RD:
 239
 240                         spin_lock_irqsave(&efi_rtc_lock, flags);
 241
 242                         status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);
 243
 244                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 245
 246                         if (status != EFI_SUCCESS) return -EINVAL;
 247
 248                         ewp = (struct rtc_wkalrm __user *)arg;
 249
 250                         if (  put_user(enabled, &ewp->enabled)
 251                            || put_user(pending, &ewp->pending)) return -EFAULT;
 252
 253                         convert_from_efi_time(&eft, &wtime);
 254
 255                         return copy_to_user(&ewp->time, &wtime,
 256                                             sizeof(struct rtc_time)) ? -EFAULT : 0;
 257         }
 258         return -EINVAL;
 259 }
 260
 261 /*
 262  *      We enforce only one user at a time here with the open/close.
 263  *      Also clear the previous interrupt data on an open, and clean
 264  *      up things on a close.
 265  */
 266
 267 static int
 268 efi_rtc_open(struct inode *inode, struct file *file)
 269 {
 270         /*
 271          * nothing special to do here
 272          * We do accept multiple open files at the same time as we
 273          * synchronize on the per call operation.
 274          */
 275         return 0;
 276 }
 277
 278 static int
 279 efi_rtc_close(struct inode *inode, struct file *file)
 280 {
 281         return 0;
 282 }
 283
 284 /*
 285  *      The various file operations we support.
 286  */
 287
 288 static const struct file_operations efi_rtc_fops = {
 289         .owner          = THIS_MODULE,
 290         .ioctl          = efi_rtc_ioctl,
 291         .open           = efi_rtc_open,
 292         .release        = efi_rtc_close,
 293 };
 294
 295 static struct miscdevice efi_rtc_dev=
 296 {
 297         EFI_RTC_MINOR,
 298         "efirtc",
 299         &efi_rtc_fops
 300 };
 301
 302 /*
 303  *      We export RAW EFI information to /proc/driver/efirtc
 304  */
 305 static int
 306 efi_rtc_get_status(char *buf)
 307 {
 308         efi_time_t      eft, alm;
 309         efi_time_cap_t  cap;
 310         char            *p = buf;
 311         efi_bool_t      enabled, pending;
 312         unsigned long   flags;
 313
 314         memset(&eft, 0, sizeof(eft));
 315         memset(&alm, 0, sizeof(alm));
 316         memset(&cap, 0, sizeof(cap));
 317
 318         spin_lock_irqsave(&efi_rtc_lock, flags);
 319
 320         efi.get_time(&eft, &cap);
 321         efi.get_wakeup_time(&enabled, &pending, &alm);
 322
 323         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 324
 325         p += sprintf(p,
 326                      "Time           : %u:%u:%u.%09u\n"
 327                      "Date           : %u-%u-%u\n"
 328                      "Daylight       : %u\n",
 329                      eft.hour, eft.minute, eft.second, eft.nanosecond,
 330                      eft.year, eft.month, eft.day,
 331                      eft.daylight);
 332
 333         if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 334                 p += sprintf(p, "Timezone       : unspecified\n");
 335         else
 336                 /* XXX fixme: convert to string? */
 337                 p += sprintf(p, "Timezone       : %u\n", eft.timezone);
 338
 339
 340         p += sprintf(p,
 341                      "Alarm Time     : %u:%u:%u.%09u\n"
 342                      "Alarm Date     : %u-%u-%u\n"
 343                      "Alarm Daylight : %u\n"
 344                      "Enabled        : %s\n"
 345                      "Pending        : %s\n",
 346                      alm.hour, alm.minute, alm.second, alm.nanosecond,
 347                      alm.year, alm.month, alm.day,
 348                      alm.daylight,
 349                      enabled == 1 ? "yes" : "no",
 350                      pending == 1 ? "yes" : "no");
 351
 352         if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 353                 p += sprintf(p, "Timezone       : unspecified\n");
 354         else
 355                 /* XXX fixme: convert to string? */
 356                 p += sprintf(p, "Timezone       : %u\n", alm.timezone);
 357
 358         /*
 359          * now prints the capabilities
 360          */
 361         p += sprintf(p,
 362                      "Resolution     : %u\n"
 363                      "Accuracy       : %u\n"
 364                      "SetstoZero     : %u\n",
 365                       cap.resolution, cap.accuracy, cap.sets_to_zero);
 366
 367         return  p - buf;
 368 }
 369
 370 static int
 371 efi_rtc_read_proc(char *page, char **start, off_t off,
 372                                  int count, int *eof, void *data)
 373 {
 374         int len = efi_rtc_get_status(page);
 375         if (len <= off+count) *eof = 1;
 376         *start = page + off;
 377         len -= off;
 378         if (len>count) len = count;
 379         if (len<0) len = 0;
 380         return len;
 381 }
 382
 383 static int __init
 384 efi_rtc_init(void)
 385 {
 386         int ret;
 387         struct proc_dir_entry *dir;
 388
 389         printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
 390
 391         ret = misc_register(&efi_rtc_dev);
 392         if (ret) {
 393                 printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
 394                                 EFI_RTC_MINOR);
 395                 return ret;
 396         }
 397
 398         dir = create_proc_read_entry ("driver/efirtc", 0, NULL,
 399                                       efi_rtc_read_proc, NULL);
 400         if (dir == NULL) {
 401                 printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
 402                 misc_deregister(&efi_rtc_dev);
 403                 return -1;
 404         }
 405         return 0;
 406 }
 407
 408 static void __exit
 409 efi_rtc_exit(void)
 410 {
 411         /* not yet used */
 412 }
 413
 414 module_init(efi_rtc_init);
 415 module_exit(efi_rtc_exit);
 416
 417 MODULE_LICENSE("GPL");