static int virtio_mmio_probe()

in virtio_mmio.c [559:631]

• 52 lines of code
• 11 McCabe index (conditional complexity)

static int virtio_mmio_probe(struct platform_device *pdev)
{
	struct virtio_mmio_device *vm_dev;
	unsigned long magic;
	int rc;

	vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
	if (!vm_dev)
		return -ENOMEM;

	vm_dev->vdev.dev.parent = &pdev->dev;
	vm_dev->vdev.dev.release = virtio_mmio_release_dev;
	vm_dev->vdev.config = &virtio_mmio_config_ops;
	vm_dev->pdev = pdev;
	INIT_LIST_HEAD(&vm_dev->virtqueues);
	spin_lock_init(&vm_dev->lock);

	vm_dev->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(vm_dev->base))
		return PTR_ERR(vm_dev->base);

	/* Check magic value */
	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
		dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
		return -ENODEV;
	}

	/* Check device version */
	vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
	if (vm_dev->version < 1 || vm_dev->version > 2) {
		dev_err(&pdev->dev, "Version %ld not supported!\n",
				vm_dev->version);
		return -ENXIO;
	}

	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
	if (vm_dev->vdev.id.device == 0) {
		/*
		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
		 * with no function. End probing now with no error reported.
		 */
		return -ENODEV;
	}
	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);

	if (vm_dev->version == 1) {
		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);

		rc = dma_set_mask(&pdev->dev, DMA_BIT_MASK(64));
		/*
		 * In the legacy case, ensure our coherently-allocated virtio
		 * ring will be at an address expressable as a 32-bit PFN.
		 */
		if (!rc)
			dma_set_coherent_mask(&pdev->dev,
					      DMA_BIT_MASK(32 + PAGE_SHIFT));
	} else {
		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
	}
	if (rc)
		rc = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
	if (rc)
		dev_warn(&pdev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");

	platform_set_drvdata(pdev, vm_dev);

	rc = register_virtio_device(&vm_dev->vdev);
	if (rc)
		put_device(&vm_dev->vdev.dev);

	return rc;
}