1
0
Fork 0
mirror of https://gitlab.com/sortix/sortix.git synced 2023-02-13 20:55:38 -05:00
sortix--sortix/kernel/x86-family/time.cpp
2014-03-01 14:37:39 +01:00

135 lines
4.1 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/>.
x86-family/time.cpp
Retrieving the current time.
*******************************************************************************/
#include <sys/types.h>
#include <timespec.h>
#include <sortix/timespec.h>
#include <sortix/kernel/clock.h>
#include <sortix/kernel/cpu.h>
#include <sortix/kernel/interrupt.h>
#include <sortix/kernel/kernel.h>
#include <sortix/kernel/process.h>
#include <sortix/kernel/scheduler.h>
#include <sortix/kernel/time.h>
namespace Sortix {
namespace Time {
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);
}
extern Clock* realtime_clock;
extern Clock* uptime_clock;
static struct timespec tick_period;
static long tick_frequency;
static uint16_t tick_divisor;
static void OnIRQ0(CPU::InterruptRegisters* regs, void* /*user*/)
{
OnTick(tick_period, !regs->InUserspace());
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.
// TODO: Confirm whether this still happens and whether it is trigged by
// another bug in my system.
static bool did_ugly_irq0_hack = false;
if ( !did_ugly_irq0_hack )
RequestIRQ0(tick_divisor),
did_ugly_irq0_hack = true;
}
void CPUInit()
{
// Estimate the rate that interrupts will be coming at.
long desired_frequency = 100/*Hz*/;
tick_frequency = RealFrequencyOfFrequency(desired_frequency);
tick_divisor = DivisorOfFrequency(tick_frequency);
tick_period = PeriodOfFrequency(tick_frequency);
// Initialize the clocks on this system.
realtime_clock->SetCallableFromInterrupts(true);
uptime_clock->SetCallableFromInterrupts(true);
struct timespec nul_time = timespec_nul();
realtime_clock->Set(&nul_time, &tick_period);
uptime_clock->Set(&nul_time, &tick_period);
}
void InitializeProcessClocks(Process* process)
{
struct timespec nul_time = timespec_nul();
process->execute_clock.SetCallableFromInterrupts(true);
process->execute_clock.Set(&nul_time, &tick_period);
process->system_clock.SetCallableFromInterrupts(true);
process->system_clock.Set(&nul_time, &tick_period);
process->child_execute_clock.Set(&nul_time, &tick_period);
process->child_execute_clock.SetCallableFromInterrupts(true);
process->child_system_clock.Set(&nul_time, &tick_period);
process->child_system_clock.SetCallableFromInterrupts(true);
}
void Start()
{
// Handle timer interrupts if they arrive.
Interrupt::RegisterHandler(Interrupt::IRQ0, &OnIRQ0, NULL);
// Request a timer interrupt now that we can handle them safely.
RequestIRQ0(tick_divisor);
}
} // namespace Time
} // namespace Sortix