177 lines
4.6 KiB
C++
177 lines
4.6 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013.
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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 with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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time.cpp
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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 <sys/types.h>
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#include <errno.h>
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#include <timespec.h>
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#include <sortix/clock.h>
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#include <sortix/timespec.h>
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#include <sortix/kernel/platform.h>
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#include <sortix/kernel/syscall.h>
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#include <sortix/kernel/copy.h>
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#include <sortix/kernel/interrupt.h>
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#include <sortix/kernel/syscall.h>
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#include <sortix/kernel/time.h>
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#include <sortix/kernel/scheduler.h>
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#include "process.h"
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#include "sound.h"
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#ifdef PLATFORM_SERIAL
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#include "serialterminal.h"
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#endif
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#include "cpu.h"
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#if !defined(PLATFORM_X86_FAMILY)
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#error Provide a time implementation for this CPU.
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#endif
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namespace Sortix {
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namespace Time {
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struct timespec since_boot;
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struct timespec since_boot_period;
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uint16_t since_boot_divisor;
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static uint16_t DivisorOfFrequency(long frequency)
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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. Note that the divisor
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// must be small enough to fit into 16 bits.
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return 1193180 / frequency;
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}
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static long FrequencyOfDivisor(uint16_t divisor)
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{
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return 1193180 / divisor;
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}
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static long RealFrequencyOfFrequency(long frequency)
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{
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return FrequencyOfDivisor(DivisorOfFrequency(frequency));
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}
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static struct timespec PeriodOfFrequency(long frequency)
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{
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long period_ns = 1000000000L / frequency;
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return timespec_make(0, period_ns);
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}
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static void RequestIRQ0(uint16_t divisor)
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{
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CPU::OutPortB(0x43, 0x36);
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CPU::OutPortB(0x40, divisor >> 0 & 0xFF);
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CPU::OutPortB(0x40, divisor >> 8 & 0xFF);
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}
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static void InitializeTimer(long frequency)
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{
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long real_frequence = RealFrequencyOfFrequency(frequency);
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since_boot_divisor = DivisorOfFrequency(frequency);
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since_boot = timespec_nul();
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since_boot_period = PeriodOfFrequency(real_frequence);
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RequestIRQ0(since_boot_divisor);
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}
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static void OnIRQ0(CPU::InterruptRegisters* regs, void* /*user*/)
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{
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since_boot = timespec_add(since_boot, since_boot_period);
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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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static bool did_ugly_irq0_hack = false;
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if ( !did_ugly_irq0_hack )
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{
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RequestIRQ0(since_boot_divisor);
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did_ugly_irq0_hack = true;
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}
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}
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bool TryGet(clockid_t clock, struct timespec* time, struct timespec* res)
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{
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switch ( clock )
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{
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case CLOCK_REALTIME:
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return errno = ENOTSUP, false;
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case CLOCK_MONOTONIC:
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case CLOCK_BOOT:
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case CLOCK_INIT:
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// TODO: Is is possible to implement the below as atomic operations?
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Interrupt::Disable();
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if ( time )
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*time = since_boot;
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if ( res )
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*res = since_boot_period;
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Interrupt::Enable();
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return true;
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default:
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return errno = EINVAL, false;
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}
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}
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struct timespec Get(clockid_t clock, struct timespec* res)
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{
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struct timespec ret;
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if ( !TryGet(clock, &ret, res) )
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return timespec_nul();
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return ret;
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}
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uintmax_t MicrosecondsOfTimespec(struct timespec time)
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{
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uintmax_t seconds = time.tv_sec;
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uintmax_t nano_seconds = time.tv_nsec;
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return seconds * 1000000 + nano_seconds / 1000;
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}
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// TODO: This system call is for compatibility. Provide user-space with better
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// facilities such as sys_clock_gettime.
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static int sys_uptime(uintmax_t* usecssinceboot)
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{
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struct timespec now;
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if ( !TryGet(CLOCK_BOOT, &now, NULL) )
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return -1;
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uintmax_t ret = MicrosecondsOfTimespec(now);
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if ( !CopyToUser(usecssinceboot, &ret, sizeof(ret)) )
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return -1;
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return 0;
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}
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void Init()
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{
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Interrupt::RegisterHandler(Interrupt::IRQ0, &OnIRQ0, NULL);
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Syscall::Register(SYSCALL_UPTIME, (void*) sys_uptime);
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InitializeTimer(100/*Hz*/);
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}
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} // namespace Time
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} // namespace Sortix
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