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122 lines
3.3 KiB
C++
122 lines
3.3 KiB
C++
/******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along
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with Sortix. If not, see <http://www.gnu.org/licenses/>.
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time.h
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Handles interrupts whenever some time has passed and provides useful
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time-related functions to the kernel.
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******************************************************************************/
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#include <sortix/kernel/platform.h>
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#include "time.h"
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#include "interrupt.h"
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#include "process.h"
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#include "scheduler.h"
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#include <sortix/kernel/log.h>
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#include "sound.h"
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#include "syscall.h"
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#ifdef PLATFORM_SERIAL
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#include "serialterminal.h"
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#endif
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#if !defined(PLATFORM_X86_FAMILY)
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#error No time subsystem is available for this CPU
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#endif
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namespace Sortix
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{
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namespace Time
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{
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uintmax_t ticks;
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uintmax_t microsecondssinceboot;
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const uint32_t Frequency = 100; // 100 Hz
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uintmax_t MicrosecondsSinceBoot()
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{
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return microsecondssinceboot;
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}
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extern "C" void RequestIRQ0()
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{
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// The value we send to the PIT is the value to divide it's input clock
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// (1193180 Hz) by, to get our required frequency. Important to note is
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// that the divisor must be small enough to fit into 16-bits.
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const uint32_t Divisor = 1193180 / Frequency;
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// Send the command byte.
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CPU::OutPortB(0x43, 0x36);
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// Divisor has to be sent byte-wise, so split here into upper/lower bytes.
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uint8_t L = (uint8_t) (Divisor & 0xFF);
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uint8_t H = (uint8_t) ((Divisor>>8) & 0xFF);
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// Send the frequency divisor.
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CPU::OutPortB(0x40, L);
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CPU::OutPortB(0x40, H);
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}
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bool didUglyIRQ0Hack;
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int SysUptime(uintmax_t* usecssinceboot)
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{
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// TODO: Validate that usecssinceboot is a valid user-space pointer.
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*usecssinceboot = microsecondssinceboot;
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return 0;
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}
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void Init()
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{
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// Initialize our variables.
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ticks = 0;
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microsecondssinceboot = 0;
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// First, register our timer callback.
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Interrupt::RegisterHandler(Interrupt::IRQ0, &OnIRQ0, NULL);
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Syscall::Register(SYSCALL_UPTIME, (void*) SysUptime);
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didUglyIRQ0Hack = false;
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RequestIRQ0();
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}
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void OnIRQ0(CPU::InterruptRegisters* Regs, void* /*user*/)
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{
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#ifdef PLATFORM_SERIAL
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SerialTerminal::OnTick();
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#endif
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ticks++;
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microsecondssinceboot += (1000*1000)/Frequency;
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// Let the scheduler switch to the next task.
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// TODO: Let the scheduler know how long has passed.
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Scheduler::Switch(Regs);
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// TODO: There is a horrible bug that causes Sortix to only receive
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// one IRQ0 on my laptop, but it works in virtual machines. But
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// re-requesting an addtional time seems to work. Hacky and ugly.
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if ( !didUglyIRQ0Hack ) { RequestIRQ0(); didUglyIRQ0Hack = true; }
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}
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// TODO: Implement all the other useful functions regarding time.
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}
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}
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