x86: video: Allow video ROM execution to fall back to the other method

If the BIOS emulator is not available, allow use of native execution if
available, and vice versa. This can be controlled by the caller.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/ivybridge/gma.c b/arch/x86/cpu/ivybridge/gma.c
index 6cf9654..821ea25 100644
--- a/arch/x86/cpu/ivybridge/gma.c
+++ b/arch/x86/cpu/ivybridge/gma.c
@@ -758,7 +758,8 @@
 
 #ifdef CONFIG_VIDEO
 	start = get_timer(0);
-	ret = pci_run_vga_bios(dev, int15_handler, false);
+	ret = pci_run_vga_bios(dev, int15_handler, PCI_ROM_USE_NATIVE |
+			       PCI_ROM_ALLOW_FALLBACK);
 	debug("BIOS ran in %lums\n", get_timer(start));
 #endif
 	/* Post VBIOS init */
diff --git a/drivers/pci/pci_rom.c b/drivers/pci/pci_rom.c
index 5729a15..48c0a77 100644
--- a/drivers/pci/pci_rom.c
+++ b/drivers/pci/pci_rom.c
@@ -228,11 +228,12 @@
 #endif
 }
 
-int pci_run_vga_bios(pci_dev_t dev, int (*int15_handler)(void), bool emulate)
+int pci_run_vga_bios(pci_dev_t dev, int (*int15_handler)(void), int exec_method)
 {
 	struct pci_rom_header *rom, *ram;
 	int vesa_mode = -1;
 	uint16_t class;
+	bool emulate;
 	int ret;
 
 	/* Only execute VGA ROMs */
@@ -262,6 +263,29 @@
 	vesa_mode = CONFIG_FRAMEBUFFER_VESA_MODE;
 #endif
 	debug("Selected vesa mode %#x\n", vesa_mode);
+
+	if (exec_method & PCI_ROM_USE_NATIVE) {
+#ifdef CONFIG_X86
+		emulate = false;
+#else
+		if (!(exec_method & PCI_ROM_ALLOW_FALLBACK)) {
+			printf("BIOS native execution is only available on x86\n");
+			return -ENOSYS;
+		}
+		emulate = true;
+#endif
+	} else {
+#ifdef CONFIG_BIOSEMU
+		emulate = true;
+#else
+		if (!(exec_method & PCI_ROM_ALLOW_FALLBACK)) {
+			printf("BIOS emulation not available - see CONFIG_BIOSEMU\n");
+			return -ENOSYS;
+		}
+		emulate = false;
+#endif
+	}
+
 	if (emulate) {
 #ifdef CONFIG_BIOSEMU
 		BE_VGAInfo *info;
@@ -274,9 +298,6 @@
 				  vesa_mode, &mode_info);
 		if (ret)
 			return ret;
-#else
-		printf("BIOS emulation not available - see CONFIG_BIOSEMU\n");
-		return -ENOSYS;
 #endif
 	} else {
 #ifdef CONFIG_X86
@@ -284,9 +305,6 @@
 
 		bios_run_on_x86(dev, (unsigned long)ram, vesa_mode,
 				&mode_info);
-#else
-		printf("BIOS native execution is only available on x86\n");
-		return -ENOSYS;
 #endif
 	}
 	debug("Final vesa mode %#x\n", mode_info.video_mode);
diff --git a/drivers/video/vesa_fb.c b/drivers/video/vesa_fb.c
index 3a0fea2..9164f8d 100644
--- a/drivers/video/vesa_fb.c
+++ b/drivers/video/vesa_fb.c
@@ -42,8 +42,8 @@
 			printf("no card detected\n");
 			return NULL;
 		}
-		printf("bdf %x\n", dev);
-		ret = pci_run_vga_bios(dev, NULL, true);
+		ret = pci_run_vga_bios(dev, NULL, PCI_ROM_USE_NATIVE |
+				       PCI_ROM_ALLOW_FALLBACK);
 		if (ret) {
 			printf("failed to run video BIOS: %d\n", ret);
 			return NULL;
@@ -59,7 +59,7 @@
 	sprintf(gdev->modeIdent, "%dx%dx%d", gdev->winSizeX, gdev->winSizeY,
 		bits_per_pixel);
 	printf("%s\n", gdev->modeIdent);
-	debug("Framex buffer at %x\n", gdev->pciBase);
+	debug("Frame buffer at %x\n", gdev->pciBase);
 
 	return (void *)gdev;
 }
diff --git a/include/pci_rom.h b/include/pci_rom.h
index 4ba36eb..2f1665d 100644
--- a/include/pci_rom.h
+++ b/include/pci_rom.h
@@ -33,14 +33,25 @@
 	uint16_t reserved_2;
 };
 
+/*
+ * Determines which execution method is used and whether we allow falling back
+ * to the other if the requested method is not available.
+ */
+enum pci_rom_emul {
+	PCI_ROM_EMULATE		= 0 << 0,
+	PCI_ROM_USE_NATIVE	= 1 << 0,
+	PCI_ROM_ALLOW_FALLBACK	= 1 << 1,
+};
+
  /**
  * pci_run_vga_bios() - Run the VGA BIOS in an x86 PC
  *
  * @dev:	Video device containing the BIOS
  * @int15_handler:	Function to call to handle int 0x15
- * @emulate:	true to use the x86 emulator, false to run native
+ * @exec_method:	flags from enum pci_rom_emul
  */
-int pci_run_vga_bios(pci_dev_t dev, int (*int15_handler)(void), bool emulate);
+int pci_run_vga_bios(pci_dev_t dev, int (*int15_handler)(void),
+		     int exec_method);
 
 /**
  * board_map_oprom_vendev() - map several PCI IDs to the one the ROM expects