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
compute_yday(efi_time_t * eft)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
compute_wday(efi_time_t * eft)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
convert_to_efi_time(struct rtc_time * wtime,efi_time_t * eft)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
convert_from_efi_time(efi_time_t * eft,struct rtc_time * wtime)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
efi_rtc_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 */
efi_rtc_proc_show(struct seq_file * m,void * v)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
efi_rtc_init(void)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 */
367