efifb: Implement vga_default_device() (v2)

EFI doesn't typically make use of the legacy VGA ROM, but it may still be
configured to pass that through to a given video device. This may lead to
an inaccurate choice of default video device. Add support to efifb to pick
out the correct active video device.

v2: fix if->ifdef
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Acked-by: hpa@zytor.com
Cc: matt.fleming@intel.com
Signed-off-by: Dave Airlie <airlied@redhat.com>

arch/x86/include/asm/vga.h

@@ -17,4 +17,10 @@
 #define vga_readb(x) (*(x))
 #define vga_writeb(x, y) (*(y) = (x))
 
+#ifdef CONFIG_FB_EFI
+#define __ARCH_HAS_VGA_DEFAULT_DEVICE
+extern struct pci_dev *vga_default_device(void);
+extern void vga_set_default_device(struct pci_dev *pdev);
+#endif
+
 #endif /* _ASM_X86_VGA_H */

drivers/video/efifb.c

@@ -18,6 +18,8 @@
 
 static bool request_mem_succeeded = false;
 
+static struct pci_dev *default_vga;
+
 static struct fb_var_screeninfo efifb_defined __devinitdata = {
 	.activate		= FB_ACTIVATE_NOW,
 	.height			= -1,
@@ -298,14 +300,23 @@ static struct fb_ops efifb_ops = {
 	.fb_imageblit	= cfb_imageblit,
 };
 
+struct pci_dev *vga_default_device(void)
+{
+	return default_vga;
+}
+
+void vga_set_default_device(struct pci_dev *pdev)
+{
+	default_vga = pdev;
+}
+
 static int __init efifb_setup(char *options)
 {
 	char *this_opt;
 	int i;
+	struct pci_dev *dev = NULL;
 
-	if (!options || !*options)
-		return 0;
-
+	if (options && *options) {
 		while ((this_opt = strsep(&options, ",")) != NULL) {
 			if (!*this_opt) continue;
 
@@ -327,6 +338,32 @@ static int __init efifb_setup(char *options)
 			else if (!strncmp(this_opt, "width:", 6))
 				screen_info.lfb_width = simple_strtoul(this_opt+6, NULL, 0);
 		}
+	}
+
+	for_each_pci_dev(dev) {
+		int i;
+
+		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
+			continue;
+
+		for (i=0; i < DEVICE_COUNT_RESOURCE; i++) {
+			resource_size_t start, end;
+
+			if (!(pci_resource_flags(dev, i) & IORESOURCE_MEM))
+				continue;
+
+			start = pci_resource_start(dev, i);
+			end  = pci_resource_end(dev, i);
+
+			if (!start || !end)
+				continue;
+
+			if (screen_info.lfb_base >= start &&
+			    (screen_info.lfb_base + screen_info.lfb_size) < end)
+				default_vga = dev;
+		}
+	}
+
 	return 0;
 }