/**
 * intel_init_bios - initialize VBIOS settings & find VBT
 * @dev: DRM device
 *
 * Loads the Video BIOS and checks that the VBT exists.  Sets scratch registers
 * to appropriate values.
 *
 * VBT existence is a sanity check that is relied on by other i830_bios.c code.
 * Note that it would be better to use a BIOS call to get the VBT, as BIOSes may
 * feed an updated VBT back through that, compared to what we'll fetch using
 * this method of groping around in the BIOS data.
 *
 * Returns 0 on success, nonzero on failure.
 */
bool
intel_init_bios(struct drm_device *dev)
{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct pci_dev *pdev = dev->pdev;
	struct vbt_header *vbt = NULL;
	struct bdb_header *bdb;
	u8 __iomem *bios;
	size_t size;
	int i;

	bios = pci_map_rom(pdev, &size);
	if (!bios)
		return -1;

	/* Scour memory looking for the VBT signature */
	for (i = 0; i + 4 < size; i++) {
		if (!memcmp(bios + i, "$VBT", 4)) {
			vbt = (struct vbt_header *)(bios + i);
			break;
		}
	}

	if (!vbt) {
		DRM_ERROR("VBT signature missing\n");
		pci_unmap_rom(pdev, bios);
		return -1;
	}

	bdb = (struct bdb_header *)(bios + i + vbt->bdb_offset);

	/* Grab useful general definitions */
	parse_general_features(dev_priv, bdb);
	parse_general_definitions(dev_priv, bdb);
	parse_lfp_panel_data(dev_priv, bdb);
	parse_sdvo_panel_data(dev_priv, bdb);
	parse_sdvo_device_mapping(dev_priv, bdb);
	parse_driver_features(dev_priv, bdb);

	pci_unmap_rom(pdev, bios);

	return 0;
}
/**
 * intel_parse_bios - find VBT and initialize settings from the BIOS
 * @dev: DRM device
 *
 * Loads the Video BIOS and checks that the VBT exists.  Sets scratch registers
 * to appropriate values.
 *
 * Returns 0 on success, nonzero on failure.
 */
bool
intel_parse_bios(struct drm_device *dev)
{
	struct drm_i915_private *dev_priv = dev->dev_private;
	struct pci_dev *pdev = dev->pdev;
	struct bdb_header *bdb = NULL;
	u8 __iomem *bios = NULL;

	init_vbt_defaults(dev_priv);

	/* XXX Should this validation be moved to intel_opregion.c? */
	if (!dmi_check_system(intel_no_opregion_vbt) && dev_priv->opregion.vbt) {
		struct vbt_header *vbt = dev_priv->opregion.vbt;
		if (memcmp(vbt->signature, "$VBT", 4) == 0) {
			DRM_DEBUG_DRIVER("Using VBT from OpRegion: %20s\n",
					 vbt->signature);
			bdb = (struct bdb_header *)((char *)vbt + vbt->bdb_offset);
		} else
			dev_priv->opregion.vbt = NULL;
	}

	if (bdb == NULL) {
		struct vbt_header *vbt = NULL;
		size_t size;
		int i;

		bios = pci_map_rom(pdev, &size);
		if (!bios)
			return -1;

		/* Scour memory looking for the VBT signature */
		for (i = 0; i + 4 < size; i++) {
			if (!memcmp(bios + i, "$VBT", 4)) {
				vbt = (struct vbt_header *)(bios + i);
				break;
			}
		}

		if (!vbt) {
			DRM_ERROR("VBT signature missing\n");
			pci_unmap_rom(pdev, bios);
			return -1;
		}

		bdb = (struct bdb_header *)(bios + i + vbt->bdb_offset);
	}

	/* Grab useful general definitions */
	parse_general_features(dev_priv, bdb);
	parse_general_definitions(dev_priv, bdb);
	parse_lfp_panel_data(dev_priv, bdb);
	parse_sdvo_panel_data(dev_priv, bdb);
	parse_sdvo_device_mapping(dev_priv, bdb);
	parse_device_mapping(dev_priv, bdb);
	parse_driver_features(dev_priv, bdb);
	parse_edp(dev_priv, bdb);

	if (bios)
		pci_unmap_rom(pdev, bios);

	return 0;
}