serenity/Kernel/Arch/aarch64/RPi/Mailbox.h

/*
 * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/StringView.h>
#include <AK/Types.h>

namespace Kernel::RPi {

// Can exchange mailbox messages with the Raspberry Pi's VideoCore chip.
// https://github.com/raspberrypi/firmware/wiki/Mailbox-property-interface
class Mailbox {
public:
    // Base class for Mailbox messages. Implemented in subsystems that use Mailbox.
    class Message {
    protected:
        Message(u32 tag, u32 arguments_size);

    private:
        u32 m_tag;
        u32 m_arguments_size;
        u32 m_command_tag;
    };

    // Must be at the beginning of every command message queue
    class MessageHeader {
    public:
        MessageHeader();

        u32 queue_size() { return m_message_queue_size; }
        void set_queue_size(u32 size) { m_message_queue_size = size; }
        bool success() const;

    private:
        u32 m_message_queue_size;
        u32 m_command_tag;
    };

    // Must be at the end of every command message queue
    class MessageTail {
    private:
        u32 m_empty_tag = 0;
    };

    static Mailbox& the();

    // Sends message queue to VideoCore
    bool send_queue(void* queue, u32 queue_size) const;

    u32 query_firmware_version();

    // Returns the kernel command line as a StringView into the given buffer.
    StringView query_kernel_command_line(Bytes buffer);

    struct MemoryRange {
        u32 base;
        u32 size;
    };
    // Returns the RAM available to the CPU in the first 1GB of the physical address space.
    // FIXME: Remove in favor of parsing the device tree.
    MemoryRange query_lower_arm_memory_range();
    MemoryRange query_videocore_memory_range();
};

}