/*
  StarForth — Steady-State Virtual Machine Runtime

  Copyright (c) 2023–2025 Robert A. James
  All rights reserved.

  This file is part of the StarForth project.

  Licensed under the StarForth License, Version 1.0 (the "License");
  you may not use this file except in compliance with the License.

  You may obtain a copy of the License at:
      https://github.com/star.4th@proton.me/StarForth/LICENSE.txt

  This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
  express or implied, including but not limited to the warranties of
  merchantability, fitness for a particular purpose, and noninfringement.

 See the License for the specific language governing permissions and
 limitations under the License.

 */

/**
 * ioapic.h - I/O APIC interface (amd64 only)
 *
 * Item 4.3.5 (FABRIC.md §27.5): no I/O APIC driver existed anywhere in this
 * tree before this item. The Local APIC (apic.h) self-interrupts for the
 * timer and needs no routing; any *legacy* IRQ (i8042 keyboard's IRQ1
 * included) requires the I/O APIC to redirect it to a Local APIC vector.
 */

#ifndef STARKERNEL_IOAPIC_H
#define STARKERNEL_IOAPIC_H

#include <stdint.h>

/**
 * Locate and map the I/O APIC via the ACPI MADT (parsed from @p acpi_rsdp).
 * Also captures any Interrupt Source Override entries so legacy ISA IRQs
 * with a non-default GSI/polarity/trigger mapping route correctly.
 *
 * @param acpi_rsdp  BootInfo->acpi_table (RSDP), or NULL.
 * @return 0 on success, -1 if no MADT/I/O APIC entry was found.
 */
int ioapic_init(void *acpi_rsdp);

/**
 * Program a redirection entry for a legacy ISA IRQ, initially masked.
 * Honors an Interrupt Source Override for @p isa_irq if the MADT had one
 * (different GSI, polarity, or trigger mode); otherwise uses the ISA
 * default (GSI == isa_irq, active-high, edge-triggered) per the ACPI
 * specification's "conforms to bus" default.
 *
 * @param isa_irq       Legacy IRQ number (0-15).
 * @param vector        IDT vector to deliver (e.g. 0x21).
 * @param dest_apic_id  Destination Local APIC ID (see apic_id()).
 * @return 0 on success, -1 if ioapic_init() has not succeeded.
 */
int ioapic_route_legacy_irq(uint8_t isa_irq, uint8_t vector, uint8_t dest_apic_id);

/**
 * Clear the mask bit on a previously routed legacy IRQ's redirection entry.
 * Call only after ioapic_route_legacy_irq() has programmed it.
 */
void ioapic_unmask_legacy_irq(uint8_t isa_irq);

#endif /* STARKERNEL_IOAPIC_H */