src/devices/bus/lib/virtio/driver_utils.cc

// Copyright 2020 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 "include/lib/virtio/driver_utils.h"

#include <lib/zx/status.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zircon/compiler.h>
#include <zircon/types.h>

#include <ddktl/protocol/pci.h>

#include "include/lib/virtio/backends/pci.h"

zx::status<std::pair<zx::bti, std::unique_ptr<virtio::Backend>>> GetBtiAndBackend(
    zx_device_t* bus_device) {
  zx_status_t status;
  ddk::PciProtocolClient pci(bus_device);

  if (!pci.is_valid()) {
    return zx::error(ZX_ERR_INVALID_ARGS);
  }

  zx_pcie_device_info_t info;
  status = pci.GetDeviceInfo(&info);
  if (status != ZX_OK) {
    return zx::error(status);
  }

  zx::bti bti;
  status = pci.GetBti(0, &bti);
  if (status != ZX_OK) {
    return zx::error(status);
  }

  // Due to the similarity between Virtio 0.9.5 legacy devices and Virtio 1.0
  // transitional devices we need to check whether modern capabilities exist.
  // If no vendor capabilities are found then we will default to the legacy
  // interface.
  std::unique_ptr<virtio::Backend> backend = nullptr;
  uint8_t offset;
  if (pci.GetFirstCapability(PCI_CAP_ID_VENDOR, &offset) == ZX_OK) {
    zxlogf(TRACE, "virtio %02x:%02x.%1x using modern PCI backend", info.bus_id, info.dev_id,
           info.func_id);
    backend.reset(new virtio::PciModernBackend(std::move(pci), info));
  } else {
    zxlogf(TRACE, "virtio %02x:%02x.%1x using legacy PCI backend", info.bus_id, info.dev_id,
           info.func_id);
    backend.reset(new virtio::PciLegacyBackend(std::move(pci), info));
  }

  status = backend->Bind();
  if (status != ZX_OK) {
    return zx::error(status);
  }

  return zx::ok(std::make_pair(std::move(bti), std::move(backend)));
}