fbdev: detect primary display device

Add function helper, fb_is_primary_device().  Given struct fb_info, it will
return a nonzero value if the device is the primary display.

Currently, only the i386 is supported where the function checks for the
IORESOURCE_ROM_SHADOW flag.

Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/i386/Makefile

@@ -108,6 +108,7 @@ drivers-$(CONFIG_PCI)			+= arch/i386/pci/
 # must be linked after kernel/
 drivers-$(CONFIG_OPROFILE)		+= arch/i386/oprofile/
 drivers-$(CONFIG_PM)			+= arch/i386/power/
+drivers-$(CONFIG_FB)                    += arch/i386/video/
 
 CFLAGS += $(mflags-y)
 AFLAGS += $(mflags-y)

arch/i386/video/Makefile

@@ -0,0 +1 @@
+obj-$(CONFIG_FB)               += fbdev.o

arch/i386/video/fbdev.c

@@ -0,0 +1,34 @@
+/*
+ * arch/i386/video/fbdev.c - i386 Framebuffer
+ *
+ * Copyright (C) 2007 Antonino Daplas <adaplas@gmail.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ *
+ */
+#include <linux/fb.h>
+#include <linux/pci.h>
+
+int fb_is_primary_device(struct fb_info *info)
+{
+	struct device *device;
+	struct pci_dev *pci_dev = NULL;
+	struct resource *res = NULL;
+	int retval = 0;
+
+	device = info->device;
+
+	if (device)
+		pci_dev = to_pci_dev(device);
+
+	if (pci_dev)
+		res = &pci_dev->resource[PCI_ROM_RESOURCE];
+
+	if (res && res->flags & IORESOURCE_ROM_SHADOW)
+		retval = 1;
+
+	return retval;
+}
+EXPORT_SYMBOL(fb_is_primary_device);