linux/drivers/char/efirtc.c
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   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
  49static DEFINE_SPINLOCK(efi_rtc_lock);
  50
  51static 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
  57static 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 */
  68static inline int
  69compute_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 */
  79static int
  80compute_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
 101static void
 102convert_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
 116static void
 117convert_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
 146static 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
 263static 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
 273static 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
 282static 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
 290static 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 */
 299static int
 300efi_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
 364static int
 365efi_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
 377static int __init 
 378efi_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
 402static void __exit
 403efi_rtc_exit(void)
 404{
 405        /* not yet used */
 406}
 407
 408module_init(efi_rtc_init);
 409module_exit(efi_rtc_exit);
 410
 411MODULE_LICENSE("GPL");
 412
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