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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 <[email protected]>
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;
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;
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 
151  unsigned long flags;
152  efi_time_t eft;
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= {
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;
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 
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 
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");