drivers/char/efirtc.c

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This source file includes following definitions.
compute_yday
compute_wday
convert_to_efi_time
convert_from_efi_time
efi_rtc_ioctl
efi_rtc_proc_show
efi_rtc_init
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * EFI Time Services Driver for Linux
   4  *
   5  * Copyright (C) 1999 Hewlett-Packard Co
   6  * Copyright (C) 1999 Stephane Eranian <eranian@hpl.hp.com>
   7  *
   8  * Based on skeleton from the drivers/char/rtc.c driver by P. Gortmaker
   9  *
  10  * This code provides an architected & portable interface to the real time
  11  * clock by using EFI instead of direct bit fiddling. The functionalities are 
  12  * quite different from the rtc.c driver. The only way to talk to the device 
  13  * is by using ioctl(). There is a /proc interface which provides the raw 
  14  * information.
  15  *
  16  * Please note that we have kept the API as close as possible to the
  17  * legacy RTC. The standard /sbin/hwclock program should work normally 
  18  * when used to get/set the time.
  19  *
  20  * NOTES:
  21  *      - Locking is required for safe execution of EFI calls with regards
  22  *        to interrupts and SMP.
  23  *
  24  * TODO (December 1999):
  25  *      - provide the API to set/get the WakeUp Alarm (different from the
  26  *        rtc.c alarm).
  27  *      - SMP testing
  28  *      - Add module support
  29  */
  30 
  31 #include <linux/types.h>
  32 #include <linux/errno.h>
  33 #include <linux/miscdevice.h>
  34 #include <linux/init.h>
  35 #include <linux/rtc.h>
  36 #include <linux/proc_fs.h>
  37 #include <linux/seq_file.h>
  38 #include <linux/efi.h>
  39 #include <linux/uaccess.h>
  40 
  41 
  42 #define EFI_RTC_VERSION         "0.4"
  43 
  44 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
  45 /*
  46  * EFI Epoch is 1/1/1998
  47  */
  48 #define EFI_RTC_EPOCH           1998
  49 
  50 static DEFINE_SPINLOCK(efi_rtc_lock);
  51 
  52 static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
  53                                                         unsigned long arg);
  54 
  55 #define is_leap(year) \
  56           ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
  57 
  58 static const unsigned short int __mon_yday[2][13] =
  59 {
  60         /* Normal years.  */
  61         { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
  62         /* Leap years.  */  
  63         { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
  64 };
  65 
  66 /*
  67  * returns day of the year [0-365]
  68  */
  69 static inline int
  70 compute_yday(efi_time_t *eft)
  71 {
  72         /* efi_time_t.month is in the [1-12] so, we need -1 */
  73         return  __mon_yday[is_leap(eft->year)][eft->month-1]+ eft->day -1;
  74 }
  75 /*
  76  * returns day of the week [0-6] 0=Sunday
  77  *
  78  * Don't try to provide a year that's before 1998, please !
  79  */
  80 static int
  81 compute_wday(efi_time_t *eft)
  82 {
  83         int y;
  84         int ndays = 0;
  85 
  86         if ( eft->year < 1998 ) {
  87                 printk(KERN_ERR "efirtc: EFI year < 1998, invalid date\n");
  88                 return -1;
  89         }
  90 
  91         for(y=EFI_RTC_EPOCH; y < eft->year; y++ ) {
  92                 ndays += 365 + (is_leap(y) ? 1 : 0);
  93         }
  94         ndays += compute_yday(eft);
  95 
  96         /*
  97          * 4=1/1/1998 was a Thursday
  98          */
  99         return (ndays + 4) % 7;
 100 }
 101 
 102 static void
 103 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
 104 {
 105 
 106         eft->year       = wtime->tm_year + 1900;
 107         eft->month      = wtime->tm_mon + 1; 
 108         eft->day        = wtime->tm_mday;
 109         eft->hour       = wtime->tm_hour;
 110         eft->minute     = wtime->tm_min;
 111         eft->second     = wtime->tm_sec;
 112         eft->nanosecond = 0; 
 113         eft->daylight   = wtime->tm_isdst ? EFI_ISDST: 0;
 114         eft->timezone   = EFI_UNSPECIFIED_TIMEZONE;
 115 }
 116 
 117 static void
 118 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
 119 {
 120         memset(wtime, 0, sizeof(*wtime));
 121         wtime->tm_sec  = eft->second;
 122         wtime->tm_min  = eft->minute;
 123         wtime->tm_hour = eft->hour;
 124         wtime->tm_mday = eft->day;
 125         wtime->tm_mon  = eft->month - 1;
 126         wtime->tm_year = eft->year - 1900;
 127 
 128         /* day of the week [0-6], Sunday=0 */
 129         wtime->tm_wday = compute_wday(eft);
 130 
 131         /* day in the year [1-365]*/
 132         wtime->tm_yday = compute_yday(eft);
 133 
 134 
 135         switch (eft->daylight & EFI_ISDST) {
 136                 case EFI_ISDST:
 137                         wtime->tm_isdst = 1;
 138                         break;
 139                 case EFI_TIME_ADJUST_DAYLIGHT:
 140                         wtime->tm_isdst = 0;
 141                         break;
 142                 default:
 143                         wtime->tm_isdst = -1;
 144         }
 145 }
 146 
 147 static long efi_rtc_ioctl(struct file *file, unsigned int cmd,
 148                                                         unsigned long arg)
 149 {
 150 
 151         efi_status_t    status;
 152         unsigned long   flags;
 153         efi_time_t      eft;
 154         efi_time_cap_t  cap;
 155         struct rtc_time wtime;
 156         struct rtc_wkalrm __user *ewp;
 157         unsigned char   enabled, pending;
 158 
 159         switch (cmd) {
 160                 case RTC_UIE_ON:
 161                 case RTC_UIE_OFF:
 162                 case RTC_PIE_ON:
 163                 case RTC_PIE_OFF:
 164                 case RTC_AIE_ON:
 165                 case RTC_AIE_OFF:
 166                 case RTC_ALM_SET:
 167                 case RTC_ALM_READ:
 168                 case RTC_IRQP_READ:
 169                 case RTC_IRQP_SET:
 170                 case RTC_EPOCH_READ:
 171                 case RTC_EPOCH_SET:
 172                         return -EINVAL;
 173 
 174                 case RTC_RD_TIME:
 175                         spin_lock_irqsave(&efi_rtc_lock, flags);
 176 
 177                         status = efi.get_time(&eft, &cap);
 178 
 179                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 180 
 181                         if (status != EFI_SUCCESS) {
 182                                 /* should never happen */
 183                                 printk(KERN_ERR "efitime: can't read time\n");
 184                                 return -EINVAL;
 185                         }
 186 
 187                         convert_from_efi_time(&eft, &wtime);
 188 
 189                         return copy_to_user((void __user *)arg, &wtime,
 190                                             sizeof (struct rtc_time)) ? - EFAULT : 0;
 191 
 192                 case RTC_SET_TIME:
 193 
 194                         if (!capable(CAP_SYS_TIME)) return -EACCES;
 195 
 196                         if (copy_from_user(&wtime, (struct rtc_time __user *)arg,
 197                                            sizeof(struct rtc_time)) )
 198                                 return -EFAULT;
 199 
 200                         convert_to_efi_time(&wtime, &eft);
 201 
 202                         spin_lock_irqsave(&efi_rtc_lock, flags);
 203 
 204                         status = efi.set_time(&eft);
 205 
 206                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 207 
 208                         return status == EFI_SUCCESS ? 0 : -EINVAL;
 209 
 210                 case RTC_WKALM_SET:
 211 
 212                         if (!capable(CAP_SYS_TIME)) return -EACCES;
 213 
 214                         ewp = (struct rtc_wkalrm __user *)arg;
 215 
 216                         if (  get_user(enabled, &ewp->enabled)
 217                            || copy_from_user(&wtime, &ewp->time, sizeof(struct rtc_time)) )
 218                                 return -EFAULT;
 219 
 220                         convert_to_efi_time(&wtime, &eft);
 221 
 222                         spin_lock_irqsave(&efi_rtc_lock, flags);
 223                         /*
 224                          * XXX Fixme:
 225                          * As of EFI 0.92 with the firmware I have on my
 226                          * machine this call does not seem to work quite
 227                          * right
 228                          */
 229                         status = efi.set_wakeup_time((efi_bool_t)enabled, &eft);
 230 
 231                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 232 
 233                         return status == EFI_SUCCESS ? 0 : -EINVAL;
 234 
 235                 case RTC_WKALM_RD:
 236 
 237                         spin_lock_irqsave(&efi_rtc_lock, flags);
 238 
 239                         status = efi.get_wakeup_time((efi_bool_t *)&enabled, (efi_bool_t *)&pending, &eft);
 240 
 241                         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 242 
 243                         if (status != EFI_SUCCESS) return -EINVAL;
 244 
 245                         ewp = (struct rtc_wkalrm __user *)arg;
 246 
 247                         if (  put_user(enabled, &ewp->enabled)
 248                            || put_user(pending, &ewp->pending)) return -EFAULT;
 249 
 250                         convert_from_efi_time(&eft, &wtime);
 251 
 252                         return copy_to_user(&ewp->time, &wtime,
 253                                             sizeof(struct rtc_time)) ? -EFAULT : 0;
 254         }
 255         return -ENOTTY;
 256 }
 257 
 258 /*
 259  *      The various file operations we support.
 260  */
 261 
 262 static const struct file_operations efi_rtc_fops = {
 263         .owner          = THIS_MODULE,
 264         .unlocked_ioctl = efi_rtc_ioctl,
 265         .llseek         = no_llseek,
 266 };
 267 
 268 static struct miscdevice efi_rtc_dev= {
 269         EFI_RTC_MINOR,
 270         "efirtc",
 271         &efi_rtc_fops
 272 };
 273 
 274 /*
 275  *      We export RAW EFI information to /proc/driver/efirtc
 276  */
 277 static int efi_rtc_proc_show(struct seq_file *m, void *v)
 278 {
 279         efi_time_t      eft, alm;
 280         efi_time_cap_t  cap;
 281         efi_bool_t      enabled, pending;       
 282         unsigned long   flags;
 283 
 284         memset(&eft, 0, sizeof(eft));
 285         memset(&alm, 0, sizeof(alm));
 286         memset(&cap, 0, sizeof(cap));
 287 
 288         spin_lock_irqsave(&efi_rtc_lock, flags);
 289 
 290         efi.get_time(&eft, &cap);
 291         efi.get_wakeup_time(&enabled, &pending, &alm);
 292 
 293         spin_unlock_irqrestore(&efi_rtc_lock,flags);
 294 
 295         seq_printf(m,
 296                    "Time           : %u:%u:%u.%09u\n"
 297                    "Date           : %u-%u-%u\n"
 298                    "Daylight       : %u\n",
 299                    eft.hour, eft.minute, eft.second, eft.nanosecond, 
 300                    eft.year, eft.month, eft.day,
 301                    eft.daylight);
 302 
 303         if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 304                 seq_puts(m, "Timezone       : unspecified\n");
 305         else
 306                 /* XXX fixme: convert to string? */
 307                 seq_printf(m, "Timezone       : %u\n", eft.timezone);
 308                 
 309 
 310         seq_printf(m,
 311                    "Alarm Time     : %u:%u:%u.%09u\n"
 312                    "Alarm Date     : %u-%u-%u\n"
 313                    "Alarm Daylight : %u\n"
 314                    "Enabled        : %s\n"
 315                    "Pending        : %s\n",
 316                    alm.hour, alm.minute, alm.second, alm.nanosecond, 
 317                    alm.year, alm.month, alm.day, 
 318                    alm.daylight,
 319                    enabled == 1 ? "yes" : "no",
 320                    pending == 1 ? "yes" : "no");
 321 
 322         if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 323                 seq_puts(m, "Timezone       : unspecified\n");
 324         else
 325                 /* XXX fixme: convert to string? */
 326                 seq_printf(m, "Timezone       : %u\n", alm.timezone);
 327 
 328         /*
 329          * now prints the capabilities
 330          */
 331         seq_printf(m,
 332                    "Resolution     : %u\n"
 333                    "Accuracy       : %u\n"
 334                    "SetstoZero     : %u\n",
 335                    cap.resolution, cap.accuracy, cap.sets_to_zero);
 336 
 337         return 0;
 338 }
 339 static int __init 
 340 efi_rtc_init(void)
 341 {
 342         int ret;
 343         struct proc_dir_entry *dir;
 344 
 345         printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
 346 
 347         ret = misc_register(&efi_rtc_dev);
 348         if (ret) {
 349                 printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
 350                                 EFI_RTC_MINOR);
 351                 return ret;
 352         }
 353 
 354         dir = proc_create_single("driver/efirtc", 0, NULL, efi_rtc_proc_show);
 355         if (dir == NULL) {
 356                 printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
 357                 misc_deregister(&efi_rtc_dev);
 358                 return -1;
 359         }
 360         return 0;
 361 }
 362 device_initcall(efi_rtc_init);
 363 
 364 /*
 365 MODULE_LICENSE("GPL");
 366 */
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root/drivers/char/efirtc.c

DEFINITIONS
