1 files changed, 103 insertions, 4 deletions

diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index 904fa09e6a6b..d99f5b0c8a09 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -10,10 +10,12 @@
 #define pr_fmt(fmt)	"efi: " fmt
 
 #include <linux/efi.h>
+#include <linux/fwnode.h>
 #include <linux/init.h>
 #include <linux/memblock.h>
 #include <linux/mm_types.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_fdt.h>
 #include <linux/platform_device.h>
 #include <linux/screen_info.h>
@@ -276,15 +278,112 @@ void __init efi_init(void)
 		efi_memmap_unmap();
 }
 
+static bool efifb_overlaps_pci_range(const struct of_pci_range *range)
+{
+	u64 fb_base = screen_info.lfb_base;
+
+	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
+		fb_base |= (u64)(unsigned long)screen_info.ext_lfb_base << 32;
+
+	return fb_base >= range->cpu_addr &&
+	       fb_base < (range->cpu_addr + range->size);
+}
+
+static struct device_node *find_pci_overlap_node(void)
+{
+	struct device_node *np;
+
+	for_each_node_by_type(np, "pci") {
+		struct of_pci_range_parser parser;
+		struct of_pci_range range;
+		int err;
+
+		err = of_pci_range_parser_init(&parser, np);
+		if (err) {
+			pr_warn("of_pci_range_parser_init() failed: %d\n", err);
+			continue;
+		}
+
+		for_each_of_pci_range(&parser, &range)
+			if (efifb_overlaps_pci_range(&range))
+				return np;
+	}
+	return NULL;
+}
+
+/*
+ * If the efifb framebuffer is backed by a PCI graphics controller, we have
+ * to ensure that this relation is expressed using a device link when
+ * running in DT mode, or the probe order may be reversed, resulting in a
+ * resource reservation conflict on the memory window that the efifb
+ * framebuffer steals from the PCIe host bridge.
+ */
+static int efifb_add_links(const struct fwnode_handle *fwnode,
+			   struct device *dev)
+{
+	struct device_node *sup_np;
+	struct device *sup_dev;
+
+	sup_np = find_pci_overlap_node();
+
+	/*
+	 * If there's no PCI graphics controller backing the efifb, we are
+	 * done here.
+	 */
+	if (!sup_np)
+		return 0;
+
+	sup_dev = get_dev_from_fwnode(&sup_np->fwnode);
+	of_node_put(sup_np);
+
+	/*
+	 * Return -ENODEV if the PCI graphics controller device hasn't been
+	 * registered yet.  This ensures that efifb isn't allowed to probe
+	 * and this function is retried again when new devices are
+	 * registered.
+	 */
+	if (!sup_dev)
+		return -ENODEV;
+
+	/*
+	 * If this fails, retrying this function at a later point won't
+	 * change anything. So, don't return an error after this.
+	 */
+	if (!device_link_add(dev, sup_dev, 0))
+		dev_warn(dev, "device_link_add() failed\n");
+
+	put_device(sup_dev);
+
+	return 0;
+}
+
+static const struct fwnode_operations efifb_fwnode_ops = {
+	.add_links = efifb_add_links,
+};
+
+static struct fwnode_handle efifb_fwnode = {
+	.ops = &efifb_fwnode_ops,
+};
+
 static int __init register_gop_device(void)
 {
-	void *pd;
+	struct platform_device *pd;
+	int err;
 
 	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
 		return 0;
 
-	pd = platform_device_register_data(NULL, "efi-framebuffer", 0,
-					   &screen_info, sizeof(screen_info));
-	return PTR_ERR_OR_ZERO(pd);
+	pd = platform_device_alloc("efi-framebuffer", 0);
+	if (!pd)
+		return -ENOMEM;
+
+	if (IS_ENABLED(CONFIG_PCI))
+		pd->dev.fwnode = &efifb_fwnode;
+
+	err = platform_device_add_data(pd, &screen_info, sizeof(screen_info));
+	if (err)
+		return err;
+
+	return platform_device_add(pd);
 }
 subsys_initcall(register_gop_device);