/*
 * Copyright (c) 2021, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <Kernel/VirtIO/VirtIORNG.h>

namespace Kernel {

VirtIORNG::VirtIORNG(PCI::Address address)
    : CharacterDevice(10, 183)
    , VirtIODevice(address, "VirtIORNG")
{
    bool success = negotiate_features([&](auto) {
        return 0;
    });
    if (success) {
        success = setup_queues(1);
    }
    if (success) {
        finish_init();
        m_entropy_buffer = MM.allocate_contiguous_kernel_region(PAGE_SIZE, "VirtIORNG", Region::Access::Read | Region::Access::Write);
        if (m_entropy_buffer) {
            memset(m_entropy_buffer->vaddr().as_ptr(), 0, m_entropy_buffer->size());
            supply_buffer_and_notify(REQUESTQ, ScatterGatherList::create_from_physical(m_entropy_buffer->physical_page(0)->paddr(), m_entropy_buffer->size()), BufferType::DeviceWritable, m_entropy_buffer->vaddr().as_ptr());
        }
    }
}

VirtIORNG::~VirtIORNG()
{
}

bool VirtIORNG::handle_device_config_change()
{
    VERIFY_NOT_REACHED(); // Device has no config
}

void VirtIORNG::handle_queue_update(u16 queue_index)
{
    VERIFY(queue_index == REQUESTQ);
    size_t available_entropy = 0;
    if (!get_queue(REQUESTQ).get_buffer(&available_entropy))
        return;
    dbgln_if(VIRTIO_DEBUG, "VirtIORNG: received {} bytes of entropy!", available_entropy);
    for (auto i = 0u; i < available_entropy; i++) {
        m_entropy_source.add_random_event(m_entropy_buffer->vaddr().as_ptr()[i]);
    }
    // TODO: when should we ask for more entropy from the host?
}

}