xref: /linux/drivers/rtc/rtc-efi.c (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * rtc-efi: RTC Class Driver for EFI-based systems
4  *
5  * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
6  *
7  * Author: dann frazier <dannf@dannf.org>
8  * Based on efirtc.c by Stephane Eranian
9  */
10 
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/stringify.h>
16 #include <linux/time.h>
17 #include <linux/platform_device.h>
18 #include <linux/rtc.h>
19 #include <linux/efi.h>
20 
21 #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT)
22 
23 /*
24  * returns day of the year [0-365]
25  */
26 static inline int
compute_yday(efi_time_t * eft)27 compute_yday(efi_time_t *eft)
28 {
29 	/* efi_time_t.month is in the [1-12] so, we need -1 */
30 	return rtc_year_days(eft->day, eft->month - 1, eft->year);
31 }
32 
33 /*
34  * returns day of the week [0-6] 0=Sunday
35  */
36 static int
compute_wday(efi_time_t * eft,int yday)37 compute_wday(efi_time_t *eft, int yday)
38 {
39 	int ndays = eft->year * (365 % 7)
40 		    + (eft->year - 1) / 4
41 		    - (eft->year - 1) / 100
42 		    + (eft->year - 1) / 400
43 		    + yday;
44 
45 	/*
46 	 * 1/1/0000 may or may not have been a Sunday (if it ever existed at
47 	 * all) but assuming it was makes this calculation work correctly.
48 	 */
49 	return ndays % 7;
50 }
51 
52 static void
convert_to_efi_time(struct rtc_time * wtime,efi_time_t * eft)53 convert_to_efi_time(struct rtc_time *wtime, efi_time_t *eft)
54 {
55 	eft->year	= wtime->tm_year + 1900;
56 	eft->month	= wtime->tm_mon + 1;
57 	eft->day	= wtime->tm_mday;
58 	eft->hour	= wtime->tm_hour;
59 	eft->minute	= wtime->tm_min;
60 	eft->second	= wtime->tm_sec;
61 	eft->nanosecond = 0;
62 	eft->daylight	= wtime->tm_isdst ? EFI_ISDST : 0;
63 	eft->timezone	= EFI_UNSPECIFIED_TIMEZONE;
64 }
65 
66 static bool
convert_from_efi_time(efi_time_t * eft,struct rtc_time * wtime)67 convert_from_efi_time(efi_time_t *eft, struct rtc_time *wtime)
68 {
69 	memset(wtime, 0, sizeof(*wtime));
70 
71 	if (eft->second >= 60)
72 		return false;
73 	wtime->tm_sec  = eft->second;
74 
75 	if (eft->minute >= 60)
76 		return false;
77 	wtime->tm_min  = eft->minute;
78 
79 	if (eft->hour >= 24)
80 		return false;
81 	wtime->tm_hour = eft->hour;
82 
83 	if (!eft->day || eft->day > 31)
84 		return false;
85 	wtime->tm_mday = eft->day;
86 
87 	if (!eft->month || eft->month > 12)
88 		return false;
89 	wtime->tm_mon  = eft->month - 1;
90 
91 	if (eft->year < 1900 || eft->year > 9999)
92 		return false;
93 	wtime->tm_year = eft->year - 1900;
94 
95 	/* day in the year [1-365]*/
96 	wtime->tm_yday = compute_yday(eft);
97 
98 	/* day of the week [0-6], Sunday=0 */
99 	wtime->tm_wday = compute_wday(eft, wtime->tm_yday);
100 
101 	switch (eft->daylight & EFI_ISDST) {
102 	case EFI_ISDST:
103 		wtime->tm_isdst = 1;
104 		break;
105 	case EFI_TIME_ADJUST_DAYLIGHT:
106 		wtime->tm_isdst = 0;
107 		break;
108 	default:
109 		wtime->tm_isdst = -1;
110 	}
111 
112 	return true;
113 }
114 
efi_read_alarm(struct device * dev,struct rtc_wkalrm * wkalrm)115 static int efi_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
116 {
117 	efi_time_t eft;
118 	efi_status_t status;
119 
120 	/*
121 	 * As of EFI v1.10, this call always returns an unsupported status
122 	 */
123 	status = efi.get_wakeup_time((efi_bool_t *)&wkalrm->enabled,
124 				     (efi_bool_t *)&wkalrm->pending, &eft);
125 
126 	if (status != EFI_SUCCESS)
127 		return -EINVAL;
128 
129 	if (!convert_from_efi_time(&eft, &wkalrm->time))
130 		return -EIO;
131 
132 	return rtc_valid_tm(&wkalrm->time);
133 }
134 
efi_set_alarm(struct device * dev,struct rtc_wkalrm * wkalrm)135 static int efi_set_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
136 {
137 	efi_time_t eft;
138 	efi_status_t status;
139 
140 	convert_to_efi_time(&wkalrm->time, &eft);
141 
142 	/*
143 	 * XXX Fixme:
144 	 * As of EFI 0.92 with the firmware I have on my
145 	 * machine this call does not seem to work quite
146 	 * right
147 	 *
148 	 * As of v1.10, this call always returns an unsupported status
149 	 */
150 	status = efi.set_wakeup_time((efi_bool_t)wkalrm->enabled, &eft);
151 
152 	dev_warn(dev, "write status is %d\n", (int)status);
153 
154 	return status == EFI_SUCCESS ? 0 : -EINVAL;
155 }
156 
efi_read_time(struct device * dev,struct rtc_time * tm)157 static int efi_read_time(struct device *dev, struct rtc_time *tm)
158 {
159 	efi_status_t status;
160 	efi_time_t eft;
161 	efi_time_cap_t cap;
162 
163 	status = efi.get_time(&eft, &cap);
164 
165 	if (status != EFI_SUCCESS) {
166 		/* should never happen */
167 		dev_err_once(dev, "can't read time\n");
168 		return -EINVAL;
169 	}
170 
171 	if (!convert_from_efi_time(&eft, tm))
172 		return -EIO;
173 
174 	return 0;
175 }
176 
efi_set_time(struct device * dev,struct rtc_time * tm)177 static int efi_set_time(struct device *dev, struct rtc_time *tm)
178 {
179 	efi_status_t status;
180 	efi_time_t eft;
181 
182 	convert_to_efi_time(tm, &eft);
183 
184 	status = efi.set_time(&eft);
185 
186 	return status == EFI_SUCCESS ? 0 : -EINVAL;
187 }
188 
efi_procfs(struct device * dev,struct seq_file * seq)189 static int efi_procfs(struct device *dev, struct seq_file *seq)
190 {
191 	efi_time_t        eft, alm;
192 	efi_time_cap_t    cap;
193 	efi_bool_t        enabled, pending;
194 	struct rtc_device *rtc = dev_get_drvdata(dev);
195 
196 	memset(&eft, 0, sizeof(eft));
197 	memset(&alm, 0, sizeof(alm));
198 	memset(&cap, 0, sizeof(cap));
199 
200 	efi.get_time(&eft, &cap);
201 	efi.get_wakeup_time(&enabled, &pending, &alm);
202 
203 	seq_printf(seq,
204 		   "Time\t\t: %u:%u:%u.%09u\n"
205 		   "Date\t\t: %u-%u-%u\n"
206 		   "Daylight\t: %u\n",
207 		   eft.hour, eft.minute, eft.second, eft.nanosecond,
208 		   eft.year, eft.month, eft.day,
209 		   eft.daylight);
210 
211 	if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
212 		seq_puts(seq, "Timezone\t: unspecified\n");
213 	else
214 		/* XXX fixme: convert to string? */
215 		seq_printf(seq, "Timezone\t: %u\n", eft.timezone);
216 
217 	if (test_bit(RTC_FEATURE_ALARM, rtc->features)) {
218 		seq_printf(seq,
219 			   "Alarm Time\t: %u:%u:%u.%09u\n"
220 			   "Alarm Date\t: %u-%u-%u\n"
221 			   "Alarm Daylight\t: %u\n"
222 			   "Enabled\t\t: %s\n"
223 			   "Pending\t\t: %s\n",
224 			   alm.hour, alm.minute, alm.second, alm.nanosecond,
225 			   alm.year, alm.month, alm.day,
226 			   alm.daylight,
227 			   enabled == 1 ? "yes" : "no",
228 			   pending == 1 ? "yes" : "no");
229 
230 		if (alm.timezone == EFI_UNSPECIFIED_TIMEZONE)
231 			seq_puts(seq, "Timezone\t: unspecified\n");
232 		else
233 			/* XXX fixme: convert to string? */
234 			seq_printf(seq, "Timezone\t: %u\n", alm.timezone);
235 	}
236 
237 	/*
238 	 * now prints the capabilities
239 	 */
240 	seq_printf(seq,
241 		   "Resolution\t: %u\n"
242 		   "Accuracy\t: %u\n"
243 		   "SetstoZero\t: %u\n",
244 		   cap.resolution, cap.accuracy, cap.sets_to_zero);
245 
246 	return 0;
247 }
248 
249 static const struct rtc_class_ops efi_rtc_ops = {
250 	.read_time	= efi_read_time,
251 	.set_time	= efi_set_time,
252 	.read_alarm	= efi_read_alarm,
253 	.set_alarm	= efi_set_alarm,
254 	.proc		= efi_procfs,
255 };
256 
efi_rtc_probe(struct platform_device * dev)257 static int __init efi_rtc_probe(struct platform_device *dev)
258 {
259 	struct rtc_device *rtc;
260 	efi_time_t eft;
261 	efi_time_cap_t cap;
262 
263 	/* First check if the RTC is usable */
264 	if (efi.get_time(&eft, &cap) != EFI_SUCCESS)
265 		return -ENODEV;
266 
267 	rtc = devm_rtc_allocate_device(&dev->dev);
268 	if (IS_ERR(rtc))
269 		return PTR_ERR(rtc);
270 
271 	platform_set_drvdata(dev, rtc);
272 
273 	rtc->ops = &efi_rtc_ops;
274 	clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->features);
275 	if (efi_rt_services_supported(EFI_RT_SUPPORTED_WAKEUP_SERVICES))
276 		set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->features);
277 	else
278 		clear_bit(RTC_FEATURE_ALARM, rtc->features);
279 
280 	device_init_wakeup(&dev->dev, true);
281 
282 	return devm_rtc_register_device(rtc);
283 }
284 
285 static struct platform_driver efi_rtc_driver = {
286 	.driver = {
287 		.name = "rtc-efi",
288 	},
289 };
290 
291 module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
292 
293 MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
294 MODULE_LICENSE("GPL");
295 MODULE_DESCRIPTION("EFI RTC driver");
296 MODULE_ALIAS("platform:rtc-efi");
297