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/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);