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/smp_lock.h>
  32 #include <linux/types.h>
  33 #include <linux/errno.h>
  34 #include <linux/miscdevice.h>
  35 #include <linux/module.h>
  36 #include <linux/init.h>
  37 #include <linux/rtc.h>
  38 #include <linux/proc_fs.h>
  39 #include <linux/efi.h>
  40
  41 #include <asm/uaccess.h>
  42 #include <asm/system.h>
  43
  44 #define EFI_RTC_VERSION         "0.4"
  45
  46 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
  47 /*
  48  * EFI Epoch is 1/1/1998
  49  */
  50 #define EFI_RTC_EPOCH           1998
  51
  52 static DEFINE_SPINLOCK(efi_rtc_lock);
  53
  54 static int efi_rtc_ioctl(struct inode *inode, struct file *file,
  55                      unsigned int cmd, unsigned long arg);
  56
  57 #define is_leap(year) \
  58           ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
  59
  60 static const unsigned short int __mon_yday[2][13] =
  61 {
  62         /* Normal years.  */
  63         { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
  64         /* Leap years.  */
  65         { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
  66 };
  67
  68 /*
  69  * returns day of the year [0-365]
  70  */
  71 static inline int
  72 compute_yday(efi_time_t *eft)
  73 {
  74         /* efi_time_t.month is in the [1-12] so, we need -1 */
  75         return  __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
  76 }
  77 /*
  78  * returns day of the week [0-6] 0=Sunday
  79  *
  80  * Don't try to provide a year that's before 1998, please !
  81  */
  82 static int
  83 compute_wday(efi_time_t *eft)
  84 {
  85         int y;
  86         int ndays = 0;
  87
  88         if ( eft->year < 1998 ) {
  89                 printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
  90                 return -1;
  91         }
  92
  93         for(y=EFI_RTC_EPOCH; y < eft->year; y++ ) {
  94                 ndays += 365 + (is_leap(y) ? 1 : 0);
  95         }
  96         ndays += compute_yday(eft);
  97
  98         /*
  99          * 4=1/1/1998 was a Thursday
 100          */
 101         return (ndays + 4) % 7;
 102 }
 103
 104 static void
 105 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
 106 {
 107
 108         eft->year       = wtime->tm_year + 1900;
 109         eft->month      = wtime->tm_mon + 1;
 110         eft->day        = wtime->tm_mday;
 111         eft->hour       = wtime->tm_hour;
 112         eft->minute     = wtime->tm_min;
 113         eft->second     = wtime->tm_sec;
 114         eft->nanosecond = 0;
 115         eft->daylight   = wtime->tm_isdst ? EFI_ISDST: 0;
 116         eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
 117 }
 118
 119 static void
 120 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
 121 {
 122         memset(wtime, 0, sizeof(*wtime));
 123         wtime->tm_sec  = eft->second;
 124         wtime->tm_min  = eft->minute;
 125         wtime->tm_hour = eft->hour;
 126         wtime->tm_mday = eft->day;
 127         wtime->tm_mon  = eft->month - 1;
 128         wtime->tm_year = eft->year - 1900;
 129
 130         /* day of the week [0-6], Sunday=0 */
 131         wtime->tm_wday = compute_wday(eft);
 132
 133         /* day in the year [1-365]*/
 134         wtime->tm_yday = compute_yday(eft);
 135
 136
 137         switch (eft->daylight & EFI_ISDST) {
 138                 case EFI_ISDST:
 139                         wtime->tm_isdst = 1;
 140                         break;
 141                 case EFI_TIME_ADJUST_DAYLIGHT:
 142                         wtime->tm_isdst = 0;
 143                         break;
 144                 default:
 145                         wtime->tm_isdst = -1;
 146         }
 147 }
 148
 149 static int
 150 efi_rtc_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
 151                      unsigned long arg)
 152 {
 153
 154         efi_status_t    status;
 155         unsigned long   flags;
 156         efi_time_t      eft;
 157         efi_time_cap_t  cap;
 158         struct rtc_time wtime;
 159         struct rtc_wkalrm __user *ewp;
 160         unsigned char   enabled, pending;
 161
 162         switch (cmd) {
 163                 case RTC_UIE_ON:
 164                 case RTC_UIE_OFF:
 165                 case RTC_PIE_ON:
 166                 case RTC_PIE_OFF:
 167                 case RTC_AIE_ON:
 168                 case RTC_AIE_OFF:
 169                 case RTC_ALM_SET:
 170                 case RTC_ALM_READ:
 171                 case RTC_IRQP_READ:
 172                 case RTC_IRQP_SET:
 173                 case RTC_EPOCH_READ:
 174                 case RTC_EPOCH_SET:
 175                         return -EINVAL;
 176
 177                 case RTC_RD_TIME:
 178
 179                         spin_lock_irqsave(&efi_rtc_lock, flags);
 180
 181                         status = efi.get_time(&eft, &cap);
 182
 183                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 184
 185                         if (status != EFI_SUCCESS) {
 186                                 /* should never happen */
 187                                 printk(KERN_ERR "efitime: can't read time\n");
 188                                 return -EINVAL;
 189                         }
 190
 191                         convert_from_efi_time(&eft, &wtime);
 192
 193                         return copy_to_user((void __user *)arg, &wtime,
 194                                             sizeof (struct rtc_time)) ? - EFAULT : 0;
 195
 196                 case RTC_SET_TIME:
 197
 198                         if (!capable(CAP_SYS_TIME)) return -EACCES;
 199
 200                         if (copy_from_user(&wtime, (struct rtc_time __user *)arg,
 201                                            sizeof(struct rtc_time)) )
 202                                 return -EFAULT;
 203
 204                         convert_to_efi_time(&wtime, &eft);
 205
 206                         spin_lock_irqsave(&efi_rtc_lock, flags);
 207
 208                         status = efi.set_time(&eft);
 209
 210                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 211
 212                         return status == EFI_SUCCESS ? 0 : -EINVAL;
 213
 214                 case RTC_WKALM_SET:
 215
 216                         if (!capable(CAP_SYS_TIME)) return -EACCES;
 217
 218                         ewp = (struct rtc_wkalrm __user *)arg;
 219
 220                         if (  get_user(enabled, &ewp->enabled)
 221                            || copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
 222                                 return -EFAULT;
 223
 224                         convert_to_efi_time(&wtime, &eft);
 225
 226                         spin_lock_irqsave(&efi_rtc_lock, flags);
 227                         /*
 228                          * XXX Fixme:
 229                          * As of EFI 0.92 with the firmware I have on my
 230                          * machine this call does not seem to work quite
 231                          * right
 232                          */
 233                         status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);
 234
 235                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 236
 237                         return status == EFI_SUCCESS ? 0 : -EINVAL;
 238
 239                 case RTC_WKALM_RD:
 240
 241                         spin_lock_irqsave(&efi_rtc_lock, flags);
 242
 243                         status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);
 244
 245                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 246
 247                         if (status != EFI_SUCCESS) return -EINVAL;
 248
 249                         ewp = (struct rtc_wkalrm __user *)arg;
 250
 251                         if (  put_user(enabled, &ewp->enabled)
 252                            || put_user(pending, &ewp->pending)) return -EFAULT;
 253
 254                         convert_from_efi_time(&eft, &wtime);
 255
 256                         return copy_to_user(&ewp->time, &wtime,
 257                                             sizeof(struct rtc_time)) ? -EFAULT : 0;
 258         }
 259         return -EINVAL;
 260 }
 261
 262 /*
 263  *      We enforce only one user at a time here with the open/close.
 264  *      Also clear the previous interrupt data on an open, and clean
 265  *      up things on a close.
 266  */
 267
 268 static int
 269 efi_rtc_open(struct inode *inode, struct file *file)
 270 {
 271         /*
 272          * nothing special to do here
 273          * We do accept multiple open files at the same time as we
 274          * synchronize on the per call operation.
 275          */
 276         cycle_kernel_lock();
 277         return 0;
 278 }
 279
 280 static int
 281 efi_rtc_close(struct inode *inode, struct file *file)
 282 {
 283         return 0;
 284 }
 285
 286 /*
 287  *      The various file operations we support.
 288  */
 289
 290 static const struct file_operations efi_rtc_fops = {
 291         .owner          = THIS_MODULE,
 292         .ioctl          = efi_rtc_ioctl,
 293         .open           = efi_rtc_open,
 294         .release        = efi_rtc_close,
 295 };
 296
 297 static struct miscdevice efi_rtc_dev=
 298 {
 299         EFI_RTC_MINOR,
 300         "efirtc",
 301         &efi_rtc_fops
 302 };
 303
 304 /*
 305  *      We export RAW EFI information to /proc/driver/efirtc
 306  */
 307 static int
 308 efi_rtc_get_status(char *buf)
 309 {
 310         efi_time_t      eft, alm;
 311         efi_time_cap_t  cap;
 312         char            *p = buf;
 313         efi_bool_t      enabled, pending;
 314         unsigned long   flags;
 315
 316         memset(&eft, 0, sizeof(eft));
 317         memset(&alm, 0, sizeof(alm));
 318         memset(&cap, 0, sizeof(cap));
 319
 320         spin_lock_irqsave(&efi_rtc_lock, flags);
 321
 322         efi.get_time(&eft, &cap);
 323         efi.get_wakeup_time(&enabled, &pending, &alm);
 324
 325         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 326
 327         p += sprintf(p,
 328                      "Time           : %u:%u:%u.%09u\n"
 329                      "Date           : %u-%u-%u\n"
 330                      "Daylight       : %u\n",
 331                      eft.hour, eft.minute, eft.second, eft.nanosecond,
 332                      eft.year, eft.month, eft.day,
 333                      eft.daylight);
 334
 335         if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 336                 p += sprintf(p, "Timezone       : unspecified\n");
 337         else
 338                 /* XXX fixme: convert to string? */
 339                 p += sprintf(p, "Timezone       : %u\n", eft.timezone);
 340
 341
 342         p += sprintf(p,
 343                      "Alarm Time     : %u:%u:%u.%09u\n"
 344                      "Alarm Date     : %u-%u-%u\n"
 345                      "Alarm Daylight : %u\n"
 346                      "Enabled        : %s\n"
 347                      "Pending        : %s\n",
 348                      alm.hour, alm.minute, alm.second, alm.nanosecond,
 349                      alm.year, alm.month, alm.day,
 350                      alm.daylight,
 351                      enabled == 1 ? "yes" : "no",
 352                      pending == 1 ? "yes" : "no");
 353
 354         if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 355                 p += sprintf(p, "Timezone       : unspecified\n");
 356         else
 357                 /* XXX fixme: convert to string? */
 358                 p += sprintf(p, "Timezone       : %u\n", alm.timezone);
 359
 360         /*
 361          * now prints the capabilities
 362          */
 363         p += sprintf(p,
 364                      "Resolution     : %u\n"
 365                      "Accuracy       : %u\n"
 366                      "SetstoZero     : %u\n",
 367                       cap.resolution, cap.accuracy, cap.sets_to_zero);
 368
 369         return  p - buf;
 370 }
 371
 372 static int
 373 efi_rtc_read_proc(char *page, char **start, off_t off,
 374                                  int count, int *eof, void *data)
 375 {
 376         int len = efi_rtc_get_status(page);
 377         if (len <= off+count) *eof = 1;
 378         *start = page + off;
 379         len -= off;
 380         if (len>count) len = count;
 381         if (len<0) len = 0;
 382         return len;
 383 }
 384
 385 static int __init
 386 efi_rtc_init(void)
 387 {
 388         int ret;
 389         struct proc_dir_entry *dir;
 390
 391         printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
 392
 393         ret = misc_register(&efi_rtc_dev);
 394         if (ret) {
 395                 printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
 396                                 EFI_RTC_MINOR);
 397                 return ret;
 398         }
 399
 400         dir = create_proc_read_entry ("driver/efirtc", 0, NULL,
 401                                       efi_rtc_read_proc, NULL);
 402         if (dir == NULL) {
 403                 printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
 404                 misc_deregister(&efi_rtc_dev);
 405                 return -1;
 406         }
 407         return 0;
 408 }
 409
 410 static void __exit
 411 efi_rtc_exit(void)
 412 {
 413         /* not yet used */
 414 }
 415
 416 module_init(efi_rtc_init);
 417 module_exit(efi_rtc_exit);
 418
 419 MODULE_LICENSE("GPL");