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/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
  50static DEFINE_SPINLOCK(efi_rtc_lock);
  51
  52static 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
  58static 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 */
  69static inline int
  70compute_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 */
  80static int
  81compute_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
 102static void
 103convert_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
 117static void
 118convert_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
 147static 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 *      We enforce only one user at a time here with the open/close.
 260 *      Also clear the previous interrupt data on an open, and clean
 261 *      up things on a close.
 262 */
 263
 264static int efi_rtc_open(struct inode *inode, struct file *file)
 265{
 266        /*
 267         * nothing special to do here
 268         * We do accept multiple open files at the same time as we
 269         * synchronize on the per call operation.
 270         */
 271        return 0;
 272}
 273
 274static int efi_rtc_close(struct inode *inode, struct file *file)
 275{
 276        return 0;
 277}
 278
 279/*
 280 *      The various file operations we support.
 281 */
 282
 283static const struct file_operations efi_rtc_fops = {
 284        .owner          = THIS_MODULE,
 285        .unlocked_ioctl = efi_rtc_ioctl,
 286        .open           = efi_rtc_open,
 287        .release        = efi_rtc_close,
 288        .llseek         = no_llseek,
 289};
 290
 291static struct miscdevice efi_rtc_dev= {
 292        EFI_RTC_MINOR,
 293        "efirtc",
 294        &efi_rtc_fops
 295};
 296
 297/*
 298 *      We export RAW EFI information to /proc/driver/efirtc
 299 */
 300static int efi_rtc_proc_show(struct seq_file *m, void *v)
 301{
 302        efi_time_t      eft, alm;
 303        efi_time_cap_t  cap;
 304        efi_bool_t      enabled, pending;       
 305        unsigned long   flags;
 306
 307        memset(&eft, 0, sizeof(eft));
 308        memset(&alm, 0, sizeof(alm));
 309        memset(&cap, 0, sizeof(cap));
 310
 311        spin_lock_irqsave(&efi_rtc_lock, flags);
 312
 313        efi.get_time(&eft, &cap);
 314        efi.get_wakeup_time(&enabled, &pending, &alm);
 315
 316        spin_unlock_irqrestore(&efi_rtc_lock,flags);
 317
 318        seq_printf(m,
 319                   "Time           : %u:%u:%u.%09u\n"
 320                   "Date           : %u-%u-%u\n"
 321                   "Daylight       : %u\n",
 322                   eft.hour, eft.minute, eft.second, eft.nanosecond, 
 323                   eft.year, eft.month, eft.day,
 324                   eft.daylight);
 325
 326        if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 327                seq_puts(m, "Timezone       : unspecified\n");
 328        else
 329                /* XXX fixme: convert to string? */
 330                seq_printf(m, "Timezone       : %u\n", eft.timezone);
 331                
 332
 333        seq_printf(m,
 334                   "Alarm Time     : %u:%u:%u.%09u\n"
 335                   "Alarm Date     : %u-%u-%u\n"
 336                   "Alarm Daylight : %u\n"
 337                   "Enabled        : %s\n"
 338                   "Pending        : %s\n",
 339                   alm.hour, alm.minute, alm.second, alm.nanosecond, 
 340                   alm.year, alm.month, alm.day, 
 341                   alm.daylight,
 342                   enabled == 1 ? "yes" : "no",
 343                   pending == 1 ? "yes" : "no");
 344
 345        if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
 346                seq_puts(m, "Timezone       : unspecified\n");
 347        else
 348                /* XXX fixme: convert to string? */
 349                seq_printf(m, "Timezone       : %u\n", alm.timezone);
 350
 351        /*
 352         * now prints the capabilities
 353         */
 354        seq_printf(m,
 355                   "Resolution     : %u\n"
 356                   "Accuracy       : %u\n"
 357                   "SetstoZero     : %u\n",
 358                   cap.resolution, cap.accuracy, cap.sets_to_zero);
 359
 360        return 0;
 361}
 362
 363static int efi_rtc_proc_open(struct inode *inode, struct file *file)
 364{
 365        return single_open(file, efi_rtc_proc_show, NULL);
 366}
 367
 368static const struct file_operations efi_rtc_proc_fops = {
 369        .open           = efi_rtc_proc_open,
 370        .read           = seq_read,
 371        .llseek         = seq_lseek,
 372        .release        = single_release,
 373};
 374
 375static int __init 
 376efi_rtc_init(void)
 377{
 378        int ret;
 379        struct proc_dir_entry *dir;
 380
 381        printk(KERN_INFO "EFI Time Services Driver v%s\n", EFI_RTC_VERSION);
 382
 383        ret = misc_register(&efi_rtc_dev);
 384        if (ret) {
 385                printk(KERN_ERR "efirtc: can't misc_register on minor=%d\n",
 386                                EFI_RTC_MINOR);
 387                return ret;
 388        }
 389
 390        dir = proc_create("driver/efirtc", 0, NULL, &efi_rtc_proc_fops);
 391        if (dir == NULL) {
 392                printk(KERN_ERR "efirtc: can't create /proc/driver/efirtc.\n");
 393                misc_deregister(&efi_rtc_dev);
 394                return -1;
 395        }
 396        return 0;
 397}
 398
 399static void __exit
 400efi_rtc_exit(void)
 401{
 402        /* not yet used */
 403}
 404
 405module_init(efi_rtc_init);
 406module_exit(efi_rtc_exit);
 407
 408MODULE_LICENSE("GPL");
 409
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