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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <AK/Assertions.h>
28#include <Kernel/CMOS.h>
29#include <Kernel/RTC.h>
30
31namespace RTC {
32
33static time_t s_boot_time;
34
35void initialize()
36{
37 s_boot_time = now();
38}
39
40time_t boot_time()
41{
42 return s_boot_time;
43}
44
45static bool update_in_progress()
46{
47 return CMOS::read(0x0a) & 0x80;
48}
49
50inline bool is_leap_year(unsigned year)
51{
52 return ((year % 4 == 0) && ((year % 100 != 0) || (year % 400) == 0));
53}
54
55static unsigned days_in_months_since_start_of_year(unsigned month, unsigned year)
56{
57 ASSERT(month <= 11);
58 unsigned days = 0;
59 switch (month) {
60 case 11:
61 days += 30;
62 [[fallthrough]];
63 case 10:
64 days += 31;
65 [[fallthrough]];
66 case 9:
67 days += 30;
68 [[fallthrough]];
69 case 8:
70 days += 31;
71 [[fallthrough]];
72 case 7:
73 days += 31;
74 [[fallthrough]];
75 case 6:
76 days += 30;
77 [[fallthrough]];
78 case 5:
79 days += 31;
80 [[fallthrough]];
81 case 4:
82 days += 30;
83 [[fallthrough]];
84 case 3:
85 days += 31;
86 [[fallthrough]];
87 case 2:
88 if (is_leap_year(year))
89 days += 29;
90 else
91 days += 28;
92 [[fallthrough]];
93 case 1:
94 days += 31;
95 }
96 return days;
97}
98
99static unsigned days_in_years_since_epoch(unsigned year)
100{
101 unsigned days = 0;
102 while (year > 1969) {
103 days += 365;
104 if (is_leap_year(year))
105 ++days;
106 --year;
107 }
108 return days;
109}
110
111u8 bcd_to_binary(u8 bcd)
112{
113 return (bcd & 0x0F) + ((bcd >> 4) * 10);
114}
115
116void read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
117{
118 while (update_in_progress())
119 ;
120
121 u8 status_b = CMOS::read(0x0b);
122
123 second = CMOS::read(0x00);
124 minute = CMOS::read(0x02);
125 hour = CMOS::read(0x04);
126 day = CMOS::read(0x07);
127 month = CMOS::read(0x08);
128 year = CMOS::read(0x09);
129
130 if (!(status_b & 0x04)) {
131 second = bcd_to_binary(second);
132 minute = bcd_to_binary(minute);
133 hour = bcd_to_binary(hour & 0x70);
134 day = bcd_to_binary(day);
135 month = bcd_to_binary(month);
136 year = bcd_to_binary(year);
137 }
138
139 if (!(status_b & 0x02) && (hour & 0x80)) {
140 hour = ((hour & 0x7F) + 12) % 24;
141 }
142
143 year += 2000;
144}
145
146time_t now()
147{
148 // FIXME: We should probably do something more robust here.
149 // Perhaps read all the values twice and verify that they were identical.
150 // We don't want to be caught in the middle of an RTC register update.
151 while (update_in_progress())
152 ;
153
154 unsigned year, month, day, hour, minute, second;
155 read_registers(year, month, day, hour, minute, second);
156
157 kprintf("year: %d, month: %d, day: %d\n", year, month, day);
158
159 ASSERT(year >= 2018);
160
161 return days_in_years_since_epoch(year - 1) * 86400
162 + days_in_months_since_start_of_year(month - 1, year) * 86400
163 + (day - 1) * 86400
164 + hour * 3600
165 + minute * 60
166 + second;
167}
168
169}