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>

2 files changed, 35 insertions, 0 deletions

diff --git a/arch/i386/video/Makefile b/arch/i386/video/Makefile
new file mode 100644
index 000000000000..2c447c94adcc
--- /dev/null
+++ b/arch/i386/video/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_FB)               += fbdev.o
diff --git a/arch/i386/video/fbdev.c b/arch/i386/video/fbdev.c
new file mode 100644
index 000000000000..7fc712c46a64
--- /dev/null
+++ b/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);