Espresso/drivers/irq.c

#include <stdio.h>
#include <drivers/ps2_keyboard.h>
#include <drivers/pit.h>
#include <port_io.h>

/* TEMP DEBUG */
#include <tty.h>

#include <kernel/syscall.h>

#include <drivers/irq.h>

#define MAX_IRQ_HANDLERS 128 /* the maximum number of irq handlers */


typedef struct {
  uint32_t irq_no;
  irq_func_t func;
} irq_handler_t;

uint32_t      num_irq_handlers = 0;
irq_handler_t handler_list[MAX_IRQ_HANDLERS];

volatile uint32_t num_irqs_missed = 0;

void irq_init(void)
{
  for (int i = 0; i < MAX_IRQ_HANDLERS; i++)
  {
    handler_list[i].irq_no = 0;
    handler_list[i].func   = NULL;
  }
  set_irq_handler(0, (irq_func_t) pit_handler);
  //set_irq_handler(1, (irq_func_t) ps2_keyboard_handler);
}

registers_t* irq_handler(uint32_t irq, registers_t* regs)
{
  uint8_t funcs_called = 0;

  if (num_irq_handlers > 0)
  {  
    for (unsigned int i = 0; i < MAX_IRQ_HANDLERS; i++)
    {
      if (handler_list[i].irq_no == irq && handler_list[i].func != NULL)
      {
        regs = handler_list[i].func(regs);
        funcs_called++;
        /* PIC IRQ acknowledgement happens in idt.c */
      }
    }
  }
  
  if (funcs_called == 0)
  {
    num_irqs_missed++;
  }

  return regs;
}

uint32_t get_interrupts_missed(void)
{
  return num_irqs_missed;
}

void set_irq_handler(uint32_t num, irq_func_t handler)
{
  if (num < MAX_IRQ_HANDLERS)
  {
    handler_list[num].irq_no = num;
    handler_list[num].func   = handler;
    
    num_irq_handlers++;
  }
}