soc/intel/common: Allow overriding CBFS filename of VBT

When reusing the same image across multiple devices, they sometimes need
different VBTs, so provide a hook for mainboard code to specify which
file is required.

Change-Id: Ic7865dc0e0c9ea3077b749d9d0482079877e9c4f
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/21724
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/vbt.c

@@ -22,12 +22,20 @@
 
 #define VBT_SIGNATURE 0x54425624
 
+__attribute__((weak))
+const char *mainboard_vbt_filename(void)
+{
+	return "vbt.bin";
+}
+
 enum cb_err locate_vbt(struct region_device *rdev)
 {
 	uint32_t vbtsig = 0;
 	struct cbfsf file_desc;
 
-	if (cbfs_boot_locate(&file_desc, "vbt.bin", NULL) < 0) {
+	const char *filename = mainboard_vbt_filename();
+
+	if (cbfs_boot_locate(&file_desc, filename, NULL) < 0) {
 		printk(BIOS_ERR, "Could not locate a VBT file in in CBFS\n");
 		return CB_ERR;
 	}

src/soc/intel/common/vbt.h

@@ -19,6 +19,14 @@
 #include <commonlib/region.h>
 #include <types.h>
 
+/*
+ * Returns the CBFS filename of the VBT blob.
+ *
+ * The default implementation returns "vbt.bin", but other implementations can
+ * override this.
+ */
+const char *mainboard_vbt_filename(void);
+
 /* locate .vbt file */
 enum cb_err locate_vbt(struct region_device *rdev);
 /*