xref: /openbmc/qemu/system/rtc.c (revision 2e1cacfb)
1 /*
2  * RTC configuration and clock read
3  *
4  * Copyright (c) 2003-2020 QEMU contributors
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to deal
8  * in the Software without restriction, including without limitation the rights
9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10  * copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22  * THE SOFTWARE.
23  */
24 
25 #include "qemu/osdep.h"
26 #include "qemu/cutils.h"
27 #include "qapi/error.h"
28 #include "qemu/error-report.h"
29 #include "qemu/option.h"
30 #include "qemu/timer.h"
31 #include "qom/object.h"
32 #include "sysemu/replay.h"
33 #include "sysemu/sysemu.h"
34 #include "sysemu/rtc.h"
35 #include "hw/rtc/mc146818rtc.h"
36 
37 static enum {
38     RTC_BASE_UTC,
39     RTC_BASE_LOCALTIME,
40     RTC_BASE_DATETIME,
41 } rtc_base_type = RTC_BASE_UTC;
42 static time_t rtc_ref_start_datetime;
43 static int rtc_realtime_clock_offset; /* used only with QEMU_CLOCK_REALTIME */
44 static int rtc_host_datetime_offset = -1; /* valid & used only with
45                                              RTC_BASE_DATETIME */
46 QEMUClockType rtc_clock;
47 /***********************************************************/
48 /* RTC reference time/date access */
49 static time_t qemu_ref_timedate(QEMUClockType clock)
50 {
51     time_t value = qemu_clock_get_ms(clock) / 1000;
52     switch (clock) {
53     case QEMU_CLOCK_REALTIME:
54         value -= rtc_realtime_clock_offset;
55         /* fall through */
56     case QEMU_CLOCK_VIRTUAL:
57         value += rtc_ref_start_datetime;
58         break;
59     case QEMU_CLOCK_HOST:
60         if (rtc_base_type == RTC_BASE_DATETIME) {
61             value -= rtc_host_datetime_offset;
62         }
63         break;
64     default:
65         g_assert_not_reached();
66     }
67     return value;
68 }
69 
70 void qemu_get_timedate(struct tm *tm, time_t offset)
71 {
72     time_t ti = qemu_ref_timedate(rtc_clock);
73 
74     ti += offset;
75 
76     switch (rtc_base_type) {
77     case RTC_BASE_DATETIME:
78     case RTC_BASE_UTC:
79         gmtime_r(&ti, tm);
80         break;
81     case RTC_BASE_LOCALTIME:
82         localtime_r(&ti, tm);
83         break;
84     }
85 }
86 
87 time_t qemu_timedate_diff(struct tm *tm)
88 {
89     time_t seconds;
90 
91     switch (rtc_base_type) {
92     case RTC_BASE_DATETIME:
93     case RTC_BASE_UTC:
94         seconds = mktimegm(tm);
95         break;
96     case RTC_BASE_LOCALTIME:
97     {
98         struct tm tmp = *tm;
99         tmp.tm_isdst = -1; /* use timezone to figure it out */
100         seconds = mktime(&tmp);
101         break;
102     }
103     default:
104         abort();
105     }
106 
107     return seconds - qemu_ref_timedate(QEMU_CLOCK_HOST);
108 }
109 
110 static void configure_rtc_base_datetime(const char *startdate)
111 {
112     time_t rtc_start_datetime;
113     struct tm tm;
114 
115     if (sscanf(startdate, "%d-%d-%dT%d:%d:%d", &tm.tm_year, &tm.tm_mon,
116                &tm.tm_mday, &tm.tm_hour, &tm.tm_min, &tm.tm_sec) == 6) {
117         /* OK */
118     } else if (sscanf(startdate, "%d-%d-%d",
119                       &tm.tm_year, &tm.tm_mon, &tm.tm_mday) == 3) {
120         tm.tm_hour = 0;
121         tm.tm_min = 0;
122         tm.tm_sec = 0;
123     } else {
124         goto date_fail;
125     }
126     tm.tm_year -= 1900;
127     tm.tm_mon--;
128     rtc_start_datetime = mktimegm(&tm);
129     if (rtc_start_datetime == -1) {
130     date_fail:
131         error_report("invalid datetime format");
132         error_printf("valid formats: "
133                      "'2006-06-17T16:01:21' or '2006-06-17'\n");
134         exit(1);
135     }
136     rtc_host_datetime_offset = rtc_ref_start_datetime - rtc_start_datetime;
137     rtc_ref_start_datetime = rtc_start_datetime;
138 }
139 
140 void configure_rtc(QemuOpts *opts)
141 {
142     const char *value;
143 
144     /* Set defaults */
145     rtc_clock = QEMU_CLOCK_HOST;
146     rtc_ref_start_datetime = qemu_clock_get_ms(QEMU_CLOCK_HOST) / 1000;
147     rtc_realtime_clock_offset = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) / 1000;
148 
149     value = qemu_opt_get(opts, "base");
150     if (value) {
151         if (!strcmp(value, "utc")) {
152             rtc_base_type = RTC_BASE_UTC;
153         } else if (!strcmp(value, "localtime")) {
154             rtc_base_type = RTC_BASE_LOCALTIME;
155             replay_add_blocker("-rtc base=localtime");
156         } else {
157             rtc_base_type = RTC_BASE_DATETIME;
158             configure_rtc_base_datetime(value);
159         }
160     }
161     value = qemu_opt_get(opts, "clock");
162     if (value) {
163         if (!strcmp(value, "host")) {
164             rtc_clock = QEMU_CLOCK_HOST;
165         } else if (!strcmp(value, "rt")) {
166             rtc_clock = QEMU_CLOCK_REALTIME;
167         } else if (!strcmp(value, "vm")) {
168             rtc_clock = QEMU_CLOCK_VIRTUAL;
169         } else {
170             error_report("invalid option value '%s'", value);
171             exit(1);
172         }
173     }
174     value = qemu_opt_get(opts, "driftfix");
175     if (value) {
176         if (!strcmp(value, "slew")) {
177             object_register_sugar_prop(TYPE_MC146818_RTC,
178                                        "lost_tick_policy",
179                                        "slew",
180                                        false);
181             if (!object_class_by_name(TYPE_MC146818_RTC)) {
182                 warn_report("driftfix 'slew' is not available with this machine");
183             }
184         } else if (!strcmp(value, "none")) {
185             /* discard is default */
186         } else {
187             error_report("invalid option value '%s'", value);
188             exit(1);
189         }
190     }
191 }
192