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sortix--sortix/sortix/time.cpp
Jonas 'Sortie' Termansen 193b76f8cb Refactor scheduler API.
2013-12-17 14:30:26 +01:00

176 lines
4.6 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012, 2013.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
Sortix. If not, see <http://www.gnu.org/licenses/>.
time.cpp
Handles interrupts whenever some time has passed and provides useful
time-related functions to the kernel.
*******************************************************************************/
#include <sys/types.h>
#include <errno.h>
#include <timespec.h>
#include <sortix/clock.h>
#include <sortix/timespec.h>
#include <sortix/kernel/platform.h>
#include <sortix/kernel/syscall.h>
#include <sortix/kernel/copy.h>
#include <sortix/kernel/interrupt.h>
#include <sortix/kernel/syscall.h>
#include <sortix/kernel/time.h>
#include <sortix/kernel/scheduler.h>
#include "process.h"
#include "sound.h"
#ifdef PLATFORM_SERIAL
#include "serialterminal.h"
#endif
#include "cpu.h"
#if !defined(PLATFORM_X86_FAMILY)
#error Provide a time implementation for this CPU.
#endif
namespace Sortix {
namespace Time {
struct timespec since_boot;
struct timespec since_boot_period;
uint16_t since_boot_divisor;
static uint16_t DivisorOfFrequency(long frequency)
{
// The value we send to the PIT is the value to divide it's input clock
// (1193180 Hz) by, to get our required frequency. Note that the divisor
// must be small enough to fit into 16 bits.
return 1193180 / frequency;
}
static long FrequencyOfDivisor(uint16_t divisor)
{
return 1193180 / divisor;
}
static long RealFrequencyOfFrequency(long frequency)
{
return FrequencyOfDivisor(DivisorOfFrequency(frequency));
}
static struct timespec PeriodOfFrequency(long frequency)
{
long period_ns = 1000000000L / frequency;
return timespec_make(0, period_ns);
}
static void RequestIRQ0(uint16_t divisor)
{
CPU::OutPortB(0x43, 0x36);
CPU::OutPortB(0x40, divisor >> 0 & 0xFF);
CPU::OutPortB(0x40, divisor >> 8 & 0xFF);
}
static void InitializeTimer(long frequency)
{
long real_frequence = RealFrequencyOfFrequency(frequency);
since_boot_divisor = DivisorOfFrequency(frequency);
since_boot = timespec_nul();
since_boot_period = PeriodOfFrequency(real_frequence);
RequestIRQ0(since_boot_divisor);
}
static void OnIRQ0(CPU::InterruptRegisters* regs, void* /*user*/)
{
since_boot = timespec_add(since_boot, since_boot_period);
Scheduler::Switch(regs);
// TODO: There is a horrible bug that causes Sortix to only receive
// one IRQ0 on my laptop, but it works in virtual machines. But
// re-requesting an addtional time seems to work. Hacky and ugly.
static bool did_ugly_irq0_hack = false;
if ( !did_ugly_irq0_hack )
{
RequestIRQ0(since_boot_divisor);
did_ugly_irq0_hack = true;
}
}
bool TryGet(clockid_t clock, struct timespec* time, struct timespec* res)
{
switch ( clock )
{
case CLOCK_REALTIME:
return errno = ENOTSUP, false;
case CLOCK_MONOTONIC:
case CLOCK_BOOT:
case CLOCK_INIT:
// TODO: Is is possible to implement the below as atomic operations?
Interrupt::Disable();
if ( time )
*time = since_boot;
if ( res )
*res = since_boot_period;
Interrupt::Enable();
return true;
default:
return errno = EINVAL, false;
}
}
struct timespec Get(clockid_t clock, struct timespec* res)
{
struct timespec ret;
if ( !TryGet(clock, &ret, res) )
return timespec_nul();
return ret;
}
uintmax_t MicrosecondsOfTimespec(struct timespec time)
{
uintmax_t seconds = time.tv_sec;
uintmax_t nano_seconds = time.tv_nsec;
return seconds * 1000000 + nano_seconds / 1000;
}
// TODO: This system call is for compatibility. Provide user-space with better
// facilities such as sys_clock_gettime.
static int sys_uptime(uintmax_t* usecssinceboot)
{
struct timespec now;
if ( !TryGet(CLOCK_BOOT, &now, NULL) )
return -1;
uintmax_t ret = MicrosecondsOfTimespec(now);
if ( !CopyToUser(usecssinceboot, &ret, sizeof(ret)) )
return -1;
return 0;
}
void Init()
{
Interrupt::RegisterHandler(Interrupt::IRQ0, &OnIRQ0, NULL);
Syscall::Register(SYSCALL_UPTIME, (void*) sys_uptime);
InitializeTimer(100/*Hz*/);
}
} // namespace Time
} // namespace Sortix