1. 根目录:
2. drivers
3. gpu
4. drm
5. virtio
6. virtgpu_drm_bus.c

/*
 * Copyright (C) 2015 Red Hat, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial
 * portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <linux/pci.h>

#include "virtgpu_drv.h"

int drm_virtio_set_busid(struct drm_device *dev, struct drm_master *master)
{
	struct pci_dev *pdev = dev->pdev;

	if (pdev) {
		return drm_pci_set_busid(dev, master);
	}
	return 0;
}

static void virtio_pci_kick_out_firmware_fb(struct pci_dev *pci_dev)
{
	struct apertures_struct *ap;
	bool primary;

	ap = alloc_apertures(1);
	if (!ap)
		return;

	ap->ranges[0].base = pci_resource_start(pci_dev, 0);
	ap->ranges[0].size = pci_resource_len(pci_dev, 0);

	primary = pci_dev->resource[PCI_ROM_RESOURCE].flags
		& IORESOURCE_ROM_SHADOW;

	remove_conflicting_framebuffers(ap, "virtiodrmfb", primary);

	kfree(ap);
}

int drm_virtio_init(struct drm_driver *driver, struct virtio_device *vdev)
{
	struct drm_device *dev;
	int ret;

	dev = drm_dev_alloc(driver, &vdev->dev);
	if (!dev)
		return -ENOMEM;
	dev->virtdev = vdev;
	vdev->priv = dev;

	if (strcmp(vdev->dev.parent->bus->name, "pci") == 0) {
		struct pci_dev *pdev = to_pci_dev(vdev->dev.parent);
		bool vga = (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;

		DRM_INFO("pci: %s detected\n",
			 vga ? "virtio-vga" : "virtio-gpu-pci");
		dev->pdev = pdev;
		if (vga)
			virtio_pci_kick_out_firmware_fb(pdev);
	}

	ret = drm_dev_register(dev, 0);
	if (ret)
		goto err_free;

	DRM_INFO("Initialized %s %d.%d.%d %s on minor %d\n", driver->name,
		 driver->major, driver->minor, driver->patchlevel,
		 driver->date, dev->primary->index);

	return 0;

err_free:
	drm_dev_unref(dev);
	return ret;
}