system/dev/bus/acpi/init.c

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stdio.h>

#include "init.h"

#define ACPI_MAX_INIT_TABLES 32

/* @brief Switch interrupts to APIC model (controls IRQ routing) */
static ACPI_STATUS set_apic_irq_mode(void) {
    ACPI_OBJECT selector = {
        .Integer.Type = ACPI_TYPE_INTEGER,
        .Integer.Value = 1, // 1 means APIC mode according to ACPI v5 5.8.1
    };
    ACPI_OBJECT_LIST params = {
        .Count = 1,
        .Pointer = &selector,
    };
    return AcpiEvaluateObject(NULL, (char*)"\\_PIC", &params, NULL);
}

ACPI_STATUS init(void) {
    // This sequence is described in section 10.1.2.1 (Full ACPICA Initialization)
    // of the ACPICA developer's reference.
    ACPI_STATUS status = AcpiInitializeSubsystem();
    if (status != AE_OK) {
        printf("WARNING: could not initialize ACPI\n");
        return status;
    }

    status = AcpiInitializeTables(NULL, ACPI_MAX_INIT_TABLES, FALSE);
    if (status == AE_NOT_FOUND) {
        printf("WARNING: could not find ACPI tables\n");
        return status;
    } else if (status == AE_NO_MEMORY) {
        printf("WARNING: could not initialize ACPI tables\n");
        return status;
    } else if (status != AE_OK) {
        printf("WARNING: could not initialize ACPI tables for unknown reason\n");
        return status;
    }

    status = AcpiLoadTables();
    if (status != AE_OK) {
        printf("WARNING: could not load ACPI tables: %d\n", status);
        return status;
    }

    status = AcpiEnableSubsystem(ACPI_FULL_INITIALIZATION);
    if (status != AE_OK) {
        printf("WARNING: could not enable ACPI\n");
        return status;
    }

    status = AcpiInitializeObjects(ACPI_FULL_INITIALIZATION);
    if (status != AE_OK) {
        printf("WARNING: could not initialize ACPI objects\n");
        return status;
    }

    status = set_apic_irq_mode();
    if (status == AE_NOT_FOUND) {
        printf("WARNING: Could not find ACPI IRQ mode switch\n");
    } else if (status != AE_OK) {
        printf("Failed to set APIC IRQ mode\n");
        return status;
    }

    // TODO(teisenbe): Maybe back out of ACPI mode on failure, but we rely on
    // ACPI for some critical things right now, so failure will likely prevent
    // successful boot anyway.
    return AE_OK;
}