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