Method Probe

src/device/virtio/virtio_driver.cpp:20–119

}

auto VirtioDriver::Probe(DeviceNode& node) -> Expected<void> {
  if (node.mmio_size == 0) {
    klog::Err("VirtioDriver: FDT reg property missing size for node '{}'",
              node.name);
    return std::unexpected(Error(ErrorCode::kInvalidArgument));
  }
  auto ctx = mmio_helper::Prepare(node, node.mmio_size);
  if (!ctx) {
    return std::unexpected(ctx.error());
  }

  etl::io_port_ro<uint32_t> magic_reg{reinterpret_cast<void*>(ctx->base)};
  if (magic_reg.read() != virtio::kMmioMagicValue) {
    return std::unexpected(Error(ErrorCode::kNotSupported));
  }

  // 读取 device_id
  etl::io_port_ro<uint32_t> device_id_reg{reinterpret_cast<void*>(
      ctx->base +
      std::to_underlying(virtio::MmioTransport::MmioReg::kDeviceId))};
  const auto device_id = static_cast<DeviceId>(device_id_reg.read());

  switch (device_id) {
    case DeviceId::kBlock: {
      if (blk_device_count_ >= kMaxBlkDevices) {
        klog::Warn(
            "VirtioDriver: blk device pool full, device at {:#x} skipped",
            ctx->base);
        return std::unexpected(Error(ErrorCode::kOutOfMemory));
      }
      const size_t idx = blk_device_count_;

      // 分配 DMA buffer
      dma_buffers_[idx] = kstd::make_unique<IoBuffer>(kMinDmaBufferSize);
      if (!dma_buffers_[idx] || !dma_buffers_[idx]->IsValid() ||
          dma_buffers_[idx]->GetBuffer().size() < kMinDmaBufferSize) {
        klog::Err("VirtioDriver: failed to allocate DMA buffer at {:#x}",
                  ctx->base);
        return std::unexpected(Error(ErrorCode::kOutOfMemory));
      }

      // Allocate slot DMA buffer
      auto [slot_size, slot_align] =
          virtio::blk::VirtioBlk<>::GetRequiredSlotMemSize();
      slot_buffers_[idx] = kstd::make_unique<IoBuffer>(slot_size, slot_align);
      if (!slot_buffers_[idx] || !slot_buffers_[idx]->IsValid()) {
        klog::Err("VirtioDriver: failed to allocate slot DMA buffer at {:#x}",
                  ctx->base);
        dma_buffers_[idx].reset();
        return std::unexpected(Error(ErrorCode::kOutOfMemory));
      }

      uint64_t extra_features =
          static_cast<uint64_t>(virtio::blk::BlkFeatureBit::kSegMax) |
          static_cast<uint64_t>(virtio::blk::BlkFeatureBit::kSizeMax) |
          static_cast<uint64_t>(virtio::blk::BlkFeatureBit::kBlkSize) |
          static_cast<uint64_t>(virtio::blk::BlkFeatureBit::kFlush) |
          static_cast<uint64_t>(virtio::blk::BlkFeatureBit::kGeometry);