Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 */
26static inline int
27compute_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 */
36static int
37compute_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
52static void
53convert_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
66static bool
67convert_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
115static int efi_read_time(struct device *dev, struct rtc_time *tm)
116{
117 efi_status_t status;
118 efi_time_t eft;
119 efi_time_cap_t cap;
120
121 status = efi.get_time(&eft, &cap);
122
123 if (status != EFI_SUCCESS) {
124 /* should never happen */
125 dev_err_once(dev, "can't read time\n");
126 return -EINVAL;
127 }
128
129 if (!convert_from_efi_time(&eft, tm))
130 return -EIO;
131
132 return 0;
133}
134
135static int efi_set_time(struct device *dev, struct rtc_time *tm)
136{
137 efi_status_t status;
138 efi_time_t eft;
139
140 convert_to_efi_time(tm, &eft);
141
142 status = efi.set_time(&eft);
143
144 return status == EFI_SUCCESS ? 0 : -EINVAL;
145}
146
147static int efi_procfs(struct device *dev, struct seq_file *seq)
148{
149 efi_time_t eft;
150 efi_time_cap_t cap;
151
152 memset(&eft, 0, sizeof(eft));
153 memset(&cap, 0, sizeof(cap));
154
155 efi.get_time(&eft, &cap);
156
157 seq_printf(seq,
158 "Time\t\t: %u:%u:%u.%09u\n"
159 "Date\t\t: %u-%u-%u\n"
160 "Daylight\t: %u\n",
161 eft.hour, eft.minute, eft.second, eft.nanosecond,
162 eft.year, eft.month, eft.day,
163 eft.daylight);
164
165 if (eft.timezone == EFI_UNSPECIFIED_TIMEZONE)
166 seq_puts(seq, "Timezone\t: unspecified\n");
167 else
168 /* XXX fixme: convert to string? */
169 seq_printf(seq, "Timezone\t: %u\n", eft.timezone);
170
171 /*
172 * now prints the capabilities
173 */
174 seq_printf(seq,
175 "Resolution\t: %u\n"
176 "Accuracy\t: %u\n"
177 "SetstoZero\t: %u\n",
178 cap.resolution, cap.accuracy, cap.sets_to_zero);
179
180 return 0;
181}
182
183static const struct rtc_class_ops efi_rtc_ops = {
184 .read_time = efi_read_time,
185 .set_time = efi_set_time,
186 .proc = efi_procfs,
187};
188
189static int __init efi_rtc_probe(struct platform_device *dev)
190{
191 struct rtc_device *rtc;
192 efi_time_t eft;
193 efi_time_cap_t cap;
194
195 /* First check if the RTC is usable */
196 if (efi.get_time(&eft, &cap) != EFI_SUCCESS)
197 return -ENODEV;
198
199 rtc = devm_rtc_allocate_device(&dev->dev);
200 if (IS_ERR(rtc))
201 return PTR_ERR(rtc);
202
203 platform_set_drvdata(dev, rtc);
204
205 rtc->ops = &efi_rtc_ops;
206 clear_bit(RTC_FEATURE_ALARM, rtc->features);
207
208 device_init_wakeup(&dev->dev, true);
209
210 return devm_rtc_register_device(rtc);
211}
212
213static struct platform_driver efi_rtc_driver = {
214 .driver = {
215 .name = "rtc-efi",
216 },
217};
218
219module_platform_driver_probe(efi_rtc_driver, efi_rtc_probe);
220
221MODULE_AUTHOR("dann frazier <dannf@dannf.org>");
222MODULE_LICENSE("GPL");
223MODULE_DESCRIPTION("EFI RTC driver");
224MODULE_ALIAS("platform:rtc-efi");