source: mainline/uspace/srv/dd/pic.c@ d51ee2b

#include <unistd.h>
#include <ddi.h>
#include <libarch/ddi.h>
#include <stdio.h>

#include "pic.h"

#define PIC1            0x20            /* IO base address for master PIC */
#define PIC2            0xA0            /* IO base address for slave PIC */
#define REG_COUNT       2                       /* command and data */

#define NAME "PIC"

static ioport8_t *pic1_cmd, *pic1_data, *pic2_cmd, *pic2_data;

static int pic_enable_ports(void *base_phys_addr, ioport8_t **pic_cmd, ioport8_t **pic_data);


int pic_init()
{       
        printf(NAME ": enabling ports 0x%x - 0x%x.\n", PIC1, PIC1 + 1);
        if (!pic_enable_ports((void *)PIC1, &pic1_cmd, &pic1_data)) {
                printf(NAME ": Error - master PIC initialization failed.\n");
                return 0;
        }
        
        printf(NAME ": enabling ports 0x%x - 0x%x.\n", PIC2, PIC2 + 1);
        if (!pic_enable_ports((void *)PIC2, &pic2_cmd, &pic2_data)) {
                printf(NAME ": Error - slave PIC initialization failed.");
                return 0;
        }
        
        printf(NAME ": initialization was successful.\n");
        return 1;
}

static int pic_enable_ports(void *base_phys_addr, ioport8_t **pic_cmd, ioport8_t **pic_data)
{
        if (pio_enable(base_phys_addr, REG_COUNT, (void **)(pic_cmd))) {  // Gain control over port's registers.
                printf(NAME ": Error - cannot gain the port %lx.\n", base_phys_addr);
                return 0;
        }
        
        *pic_data = *pic_cmd + 1;
        return 1;
}

void pic_enable_interrupt(int irq)
{
        printf(NAME ": pic_enable_interrupt %d.", irq);
        pic_enable_irqs(1 << irq);
        printf(NAME ": interrupt %d enabled.", irq);
}

void pic_enable_irqs(uint16_t irqmask)
{
        uint8_t x;

        if (irqmask & 0xff) {
                x = pio_read_8(pic1_data);
                pio_write_8(pic1_data, (uint8_t) (x & (~(irqmask & 0xff))));
        }
        if (irqmask >> 8) {
                x = pio_read_8(pic2_data);
                pio_write_8(pic2_data, (uint8_t) (x & (~(irqmask >> 8))));
        }
}