/* gic.c — GIC-400 driver for Raspberry Pi 5 */

#include "gic.h"

void gic_init(void) {
    /* Disable distributor */
    GICD_CTLR = 0;

    /* Get number of IRQs supported */
    int n = ((GICD_TYPER & 0x1F) + 1) * 32;

    /* Disable all IRQs */
    for (int i = 0; i < n / 32; i++) {
        GICD_ICENABLER(i) = 0xFFFFFFFF;
        GICD_ICACTIVER(i) = 0xFFFFFFFF;
    }

    /* Set all IRQs to lowest priority */
    for (int i = 0; i < n / 4; i++) {
        GICD_IPRIORITYR(i) = 0xA0A0A0A0;
    }

    /* Target all SPIs to CPU 0 */
    for (int i = 8; i < n / 4; i++) {
        GICD_ITARGETSR(i) = 0x01010101;  /* CPU 0 */
    }

    /* All IRQs level-triggered */
    for (int i = 0; i < n / 16; i++) {
        GICD_ICFGR(i) = 0;
    }

    /* Enable distributor */
    GICD_CTLR = 1;

    /* Set CPU interface priority mask to accept all */
    GICC_PMR = 0xFF;

    /* Enable CPU interface */
    GICC_CTLR = 1;
}

void gic_enable_irq(int irq) {
    GICD_ISENABLER(irq / 32) = (1U << (irq % 32));
}

void gic_disable_irq(int irq) {
    GICD_ICENABLER(irq / 32) = (1U << (irq % 32));
}

int gic_acknowledge(void) {
    return (int)(GICC_IAR & 0x3FF);
}

void gic_eoi(int irq) {
    GICC_EOIR = (uint32_t)irq;
}