1 files changed, 157 insertions, 0 deletions
diff --git a/drivers/video/screen_info_pci.c b/drivers/video/screen_info_pci.c
new file mode 100644
index 000000000000..66bfc1d0a6dc
--- /dev/null
+++ b/drivers/video/screen_info_pci.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pci.h>
+#include <linux/printk.h>
+#include <linux/screen_info.h>
+#include <linux/string.h>
+
+static struct pci_dev *screen_info_lfb_pdev;
+static size_t screen_info_lfb_bar;
+static resource_size_t screen_info_lfb_res_start; // original start of resource
+static resource_size_t screen_info_lfb_offset; // framebuffer offset within resource
+
+static bool __screen_info_relocation_is_valid(const struct screen_info *si, struct resource *pr)
+{
+	u64 size = __screen_info_lfb_size(si, screen_info_video_type(si));
+
+	if (screen_info_lfb_offset > resource_size(pr))
+		return false;
+	if (size > resource_size(pr))
+		return false;
+	if (resource_size(pr) - size < screen_info_lfb_offset)
+		return false;
+
+	return true;
+}
+
+void screen_info_apply_fixups(void)
+{
+	struct screen_info *si = &screen_info;
+
+	if (screen_info_lfb_pdev) {
+		struct resource *pr = &screen_info_lfb_pdev->resource[screen_info_lfb_bar];
+
+		if (pr->start != screen_info_lfb_res_start) {
+			if (__screen_info_relocation_is_valid(si, pr)) {
+				/*
+				 * Only update base if we have an actual
+				 * relocation to a valid I/O range.
+				 */
+				__screen_info_set_lfb_base(si, pr->start + screen_info_lfb_offset);
+				pr_info("Relocating firmware framebuffer to offset %pa[d] within %pr\n",
+					&screen_info_lfb_offset, pr);
+			} else {
+				pr_warn("Invalid relocating, disabling firmware framebuffer\n");
+			}
+		}
+	}
+}
+
+static int __screen_info_lfb_pci_bus_region(const struct screen_info *si, unsigned int type,
+					    struct pci_bus_region *r)
+{
+	u64 base, size;
+
+	base = __screen_info_lfb_base(si);
+	if (!base)
+		return -EINVAL;
+
+	size = __screen_info_lfb_size(si, type);
+	if (!size)
+		return -EINVAL;
+
+	r->start = base;
+	r->end = base + size - 1;
+
+	return 0;
+}
+
+static void screen_info_fixup_lfb(struct pci_dev *pdev)
+{
+	unsigned int type;
+	struct pci_bus_region bus_region;
+	int ret;
+	struct resource r = {
+		.flags = IORESOURCE_MEM,
+	};
+	const struct resource *pr;
+	const struct screen_info *si = &screen_info;
+
+	if (screen_info_lfb_pdev)
+		return; // already found
+
+	type = screen_info_video_type(si);
+	if (!__screen_info_has_lfb(type))
+		return; // only applies to EFI; maybe VESA
+
+	ret = __screen_info_lfb_pci_bus_region(si, type, &bus_region);
+	if (ret < 0)
+		return;
+
+	/*
+	 * Translate the PCI bus address to resource. Account
+	 * for an offset if the framebuffer is behind a PCI host
+	 * bridge.
+	 */
+	pcibios_bus_to_resource(pdev->bus, &r, &bus_region);
+
+	pr = pci_find_resource(pdev, &r);
+	if (!pr)
+		return;
+
+	/*
+	 * We've found a PCI device with the framebuffer
+	 * resource. Store away the parameters to track
+	 * relocation of the framebuffer aperture.
+	 */
+	screen_info_lfb_pdev = pdev;
+	screen_info_lfb_bar = pr - pdev->resource;
+	screen_info_lfb_offset = r.start - pr->start;
+	screen_info_lfb_res_start = bus_region.start;
+}
+DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY, 16,
+			       screen_info_fixup_lfb);
+
+static struct pci_dev *__screen_info_pci_dev(struct resource *res)
+{
+	struct pci_dev *pdev = NULL;
+	const struct resource *r = NULL;
+
+	if (!(res->flags & IORESOURCE_MEM))
+		return NULL;
+
+	while (!r && (pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev))) {
+		r = pci_find_resource(pdev, res);
+	}
+
+	return pdev;
+}
+
+/**
+ * screen_info_pci_dev() - Return PCI parent device that contains screen_info's framebuffer
+ * @si: the screen_info
+ *
+ * Returns:
+ * The screen_info's parent device or NULL on success, or a pointer-encoded
+ * errno value otherwise. The value NULL is not an error. It signals that no
+ * PCI device has been found.
+ */
+struct pci_dev *screen_info_pci_dev(const struct screen_info *si)
+{
+	struct resource res[SCREEN_INFO_MAX_RESOURCES];
+	ssize_t i, numres;
+
+	numres = screen_info_resources(si, res, ARRAY_SIZE(res));
+	if (numres < 0)
+		return ERR_PTR(numres);
+
+	for (i = 0; i < numres; ++i) {
+		struct pci_dev *pdev = __screen_info_pci_dev(&res[i]);
+
+		if (pdev)
+			return pdev;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(screen_info_pci_dev);