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Serenity Operating System
1/*
2 * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
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 <Kernel/Arch/i386/CPU.h>
28#include <Kernel/CMOS.h>
29#include <Kernel/Time/RTC.h>
30#include <Kernel/Time/TimeManagement.h>
31#include <LibBareMetal/IO.h>
32
33namespace Kernel {
34#define IRQ_TIMER 8
35#define MAX_FREQUENCY 8000
36
37NonnullRefPtr<RealTimeClock> RealTimeClock::create(Function<void(const RegisterState&)> callback)
38{
39 return adopt(*new RealTimeClock(move(callback)));
40}
41RealTimeClock::RealTimeClock(Function<void(const RegisterState&)> callback)
42 : HardwareTimer(IRQ_TIMER, move(callback))
43{
44 InterruptDisabler disabler;
45 NonMaskableInterruptDisabler nmi_disabler;
46 enable_irq();
47 CMOS::write(0x8B, CMOS::read(0xB) | 0x40);
48 reset_to_default_ticks_per_second();
49}
50void RealTimeClock::handle_irq(const RegisterState& regs)
51{
52 HardwareTimer::handle_irq(regs);
53 CMOS::read(0x8C);
54}
55
56size_t RealTimeClock::ticks_per_second() const
57{
58 return m_frequency;
59}
60
61void RealTimeClock::reset_to_default_ticks_per_second()
62{
63 InterruptDisabler disabler;
64 bool success = try_to_set_frequency(1024);
65 ASSERT(success);
66}
67
68// FIXME: This is a quick & dirty log base 2 with a paramater. Please provide something better in the future.
69static int quick_log2(size_t number)
70{
71 int count = 0;
72 while (number >>= 1)
73 count++;
74 return count;
75}
76
77bool RealTimeClock::try_to_set_frequency(size_t frequency)
78{
79 InterruptDisabler disabler;
80 if (!is_capable_of_frequency(frequency))
81 return false;
82 disable_irq();
83 u8 previous_rate = CMOS::read(0x8A);
84 u8 rate = quick_log2(32768 / frequency) + 1;
85 dbg() << "RTC: Set rate to " << rate;
86 CMOS::write(0x8A, (previous_rate & 0xF0) | rate);
87 m_frequency = frequency;
88 dbg() << "RTC: Set frequency to " << frequency << " Hz";
89 enable_irq();
90 return true;
91}
92bool RealTimeClock::is_capable_of_frequency(size_t frequency) const
93{
94 ASSERT(frequency != 0);
95 if (frequency > MAX_FREQUENCY)
96 return false;
97 if (32768 % frequency)
98 return false;
99
100 u16 divider = 32768 / frequency;
101 return (divider <= 16384 && divider >= 4); // Frequency can be in range of 2 Hz to 8 KHz
102}
103size_t RealTimeClock::calculate_nearest_possible_frequency(size_t frequency) const
104{
105 ASSERT(frequency != 0);
106 return frequency;
107}
108
109}