mirror of
https://github.com/RGBCube/serenity
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b285a1944e
The SysV ABI says that the DF flag should be clear on function entry. That means we have to clear it when jumping into the kernel from some random userspace context.
85 lines
1.8 KiB
C++
85 lines
1.8 KiB
C++
#include <Kernel/Arch/i386/CPU.h>
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#include <Kernel/Arch/i386/PIC.h>
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#include <Kernel/Arch/i386/PIT.h>
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#include <Kernel/IO.h>
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#include <Kernel/Scheduler.h>
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#define IRQ_TIMER 0
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extern "C" void timer_interrupt_entry();
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extern "C" void timer_interrupt_handler(RegisterDump);
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asm(
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".globl timer_interrupt_entry \n"
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"timer_interrupt_entry: \n"
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" pushl $0x0\n"
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" pusha\n"
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" pushw %ds\n"
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" pushw %es\n"
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" pushw %fs\n"
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" pushw %gs\n"
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" pushw %ss\n"
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" pushw %ss\n"
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" pushw %ss\n"
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" pushw %ss\n"
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" pushw %ss\n"
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" popw %ds\n"
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" popw %es\n"
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" popw %fs\n"
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" popw %gs\n"
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" cld\n"
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" call timer_interrupt_handler\n"
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" popw %gs\n"
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" popw %gs\n"
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" popw %fs\n"
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" popw %es\n"
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" popw %ds\n"
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" popa\n"
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" add $0x4, %esp\n"
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" iret\n");
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static u32 s_ticks_this_second;
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static u32 s_seconds_since_boot;
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void timer_interrupt_handler(RegisterDump regs)
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{
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IRQHandlerScope scope(IRQ_TIMER);
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if (++s_ticks_this_second >= TICKS_PER_SECOND) {
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// FIXME: Synchronize with the RTC somehow to prevent drifting apart.
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++s_seconds_since_boot;
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s_ticks_this_second = 0;
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}
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Scheduler::timer_tick(regs);
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}
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namespace PIT {
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u32 ticks_this_second()
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{
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return s_ticks_this_second;
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}
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u32 seconds_since_boot()
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{
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return s_seconds_since_boot;
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}
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void initialize()
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{
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u16 timer_reload;
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IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
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timer_reload = (BASE_FREQUENCY / TICKS_PER_SECOND);
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kprintf("PIT: %u Hz, square wave (%x)\n", TICKS_PER_SECOND, timer_reload);
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IO::out8(TIMER0_CTL, LSB(timer_reload));
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IO::out8(TIMER0_CTL, MSB(timer_reload));
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register_interrupt_handler(IRQ_VECTOR_BASE + IRQ_TIMER, timer_interrupt_entry);
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PIC::enable(IRQ_TIMER);
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}
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}
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