ladybird/Kernel/i8253.cpp
Andreas Kling fe237ee215 Lots of hacking:
- Turn Keyboard into a CharacterDevice (85,1) at /dev/keyboard.
- Implement MM::unmapRegionsForTask() and MM::unmapRegion()
- Save SS correctly on interrupt.
- Add a simple Spawn syscall for launching another process.
- Move a bunch of IO syscall debug output behind DEBUG_IO.
- Have ASSERT do a "cli" immediately when failing.
  This makes the output look proper every time.
- Implement a bunch of syscalls in LibC.
- Add a simple shell ("sh"). All it can do now is read a line
  of text from /dev/keyboard and then try launching the specified
  executable by calling spawn().

There are definitely bugs in here, but we're moving on forward.
2018-10-23 10:12:50 +02:00

171 lines
4.1 KiB
C++

#include "i8253.h"
#include "i386.h"
#include "IO.h"
#include "VGA.h"
#include "Task.h"
#include "system.h"
#include "PIC.h"
#define IRQ_TIMER 0
extern "C" void tick_ISR();
extern "C" void clock_handle();
extern volatile DWORD state_dump;
asm(
".globl tick_ISR \n"
".globl state_dump \n"
"state_dump: \n"
".long 0\n"
"tick_ISR: \n"
" pusha\n"
" pushw %ds\n"
" pushw %es\n"
" pushw %fs\n"
" pushw %gs\n"
" pushw %ss\n"
" pushw %ss\n"
" pushw %ss\n"
" pushw %ss\n"
" pushw %ss\n"
" popw %ds\n"
" popw %es\n"
" popw %fs\n"
" popw %gs\n"
" mov %esp, state_dump\n"
" call clock_handle\n"
" popw %gs\n"
" popw %gs\n"
" popw %fs\n"
" popw %es\n"
" popw %ds\n"
" popa\n"
" iret\n"
);
/* Timer related ports */
#define TIMER0_CTL 0x40
#define TIMER1_CTL 0x41
#define TIMER2_CTL 0x42
#define PIT_CTL 0x43
/* Building blocks for PIT_CTL */
#define TIMER0_SELECT 0x00
#define TIMER1_SELECT 0x40
#define TIMER2_SELECT 0x80
#define MODE_COUNTDOWN 0x00
#define MODE_ONESHOT 0x02
#define MODE_RATE 0x04
#define MODE_SQUARE_WAVE 0x06
#define WRITE_WORD 0x30
/* Miscellaneous */
#define BASE_FREQUENCY 1193182
void clock_handle()
{
IRQHandlerScope scope(IRQ_TIMER);
if (!current)
return;
system.uptime++;
if (current->tick())
return;
//return;
auto& regs = *reinterpret_cast<RegisterDump*>(state_dump);
current->tss().gs = regs.gs;
current->tss().fs = regs.fs;
current->tss().es = regs.es;
current->tss().ds = regs.ds;
current->tss().edi = regs.edi;
current->tss().esi = regs.esi;
current->tss().ebp = regs.ebp;
current->tss().ebx = regs.ebx;
current->tss().edx = regs.edx;
current->tss().ecx = regs.ecx;
current->tss().eax = regs.eax;
current->tss().eip = regs.eip;
current->tss().cs = regs.cs;
current->tss().eflags = regs.eflags;
#if 0
BYTE a = vga_get_attr();
WORD foo = vga_get_cursor();
vga_set_attr(0x50);
vga_set_cursor(0);
kprintf("\n\n");
kprintf("Task %u interrupted at %x \n", current->pid(), regs.eip );
kprintf("EAX=%x EBX=%x ECX=%x EDX=%x \n", regs.eax, regs.ebx, regs.ecx, regs.edx);
kprintf("ESI=%x EDI=%x EBP=%x ESP=%x \n", regs.esi, regs.edi, regs.ebp, regs.esp);
kprintf("FLAGS=%x", regs.eflags);
vga_set_cursor(foo);
vga_set_attr(a);
#endif
// Compute task ESP.
// Add 12 for CS, EIP, EFLAGS (interrupt mechanic)
// FIXME: Hmm. Should we add an extra 8 here for SS:ESP in some cases?
// If this IRQ occurred while in a user task, wouldn't that also push the stack ptr?
current->tss().esp = regs.esp + 12;
current->tss().ss = regs.ss;
if ((current->tss().cs & 3) != 0) {
#if 0
kprintf("clock'ed across to ring0\n");
kprintf("code: %w:%x\n", current->tss().cs, current->tss().eip);
kprintf(" stk: %w:%x\n", current->tss().ss, current->tss().esp);
kprintf("astk: %w:%x\n", regs.ss_if_crossRing, regs.esp_if_crossRing);
//HANG;
#endif
current->tss().ss = regs.ss_if_crossRing;
current->tss().esp = regs.esp_if_crossRing;
}
// Prepare a new task to run;
if (!scheduleNewTask())
return;
Task::prepForIRETToNewTask();
// Set the NT (nested task) flag.
asm(
"pushf\n"
"orl $0x00004000, (%esp)\n"
"popf\n"
);
}
namespace PIT {
void initialize()
{
WORD timer_reload;
IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_WORD | MODE_SQUARE_WAVE);
timer_reload = (BASE_FREQUENCY / TICKS_PER_SECOND);
/* Send LSB and MSB of timer reload value. */
kprintf("PIT(i8253): %u Hz, square wave (%x)\n", TICKS_PER_SECOND, timer_reload);
IO::out8(TIMER0_CTL, LSB(timer_reload));
IO::out8(TIMER0_CTL, MSB(timer_reload));
registerInterruptHandler(IRQ_VECTOR_BASE + IRQ_TIMER, tick_ISR);
PIC::enable(IRQ_TIMER);
}
}