fdt: add new fdt_fixup_display function to configure display

Add 'fdt_fixup_display' function to fixup device-tree native-mode property
of display-timings node to select timings for a specific display.
This is useful if a device-tree has configurations for multiple
display timings for undetectable displays.

see kernel Documentation/devicetree/bindings/video/display-timing.txt

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/include/fdt_support.h b/include/fdt_support.h
index ae5e8a3..5d4f28d 100644
--- a/include/fdt_support.h
+++ b/include/fdt_support.h
@@ -47,6 +47,19 @@
 			 const void *val, int len, int create);
 void fdt_fixup_qe_firmware(void *fdt);
 
+/**
+ * Update native-mode property of display-timings node to the phandle
+ * of the timings matching a display by name (case insensitive).
+ *
+ * see kernel Documentation/devicetree/bindings/video/display-timing.txt
+ *
+ * @param blob		FDT blob to update
+ * @param path		path within dt
+ * @param display	name of display timing to match
+ * @return 0 if ok, or -FDT_ERR_... on error
+ */
+int fdt_fixup_display(void *blob, const char *path, const char *display);
+
 #if defined(CONFIG_HAS_FSL_DR_USB) || defined(CONFIG_HAS_FSL_MPH_USB)
 void fdt_fixup_dr_usb(void *blob, bd_t *bd);
 #else