diff --git a/docs/getting_started/porting-guide.rst b/docs/getting_started/porting-guide.rst
index be04b97..7f10ca6 100644
--- a/docs/getting_started/porting-guide.rst
+++ b/docs/getting_started/porting-guide.rst
@@ -932,6 +932,25 @@
 Alongside, returns device handle and image specification from the I/O policy
 of the requested FWU metadata image.
 
+Function : plat_fwu_get_boot_idx() [when PSA_FWU_SUPPORT == 1]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Argument : void
+    Return   : uint32_t
+
+This function is mandatory when PSA_FWU_SUPPORT is enabled. It provides the
+means to retrieve the boot index value from the platform. The boot index is the
+bank from which the platform has booted the firmware images.
+
+By default, the platform will read the metadata structure and try to boot from
+the active bank. If the platform fails to boot from the active bank due to
+reasons like an Authentication failure, or on crossing a set number of watchdog
+resets while booting from the active bank, the platform can then switch to boot
+from a different bank. This function then returns the bank that the platform
+should boot its images from.
+
 Common optional modifications
 -----------------------------
 
diff --git a/include/plat/common/platform.h b/include/plat/common/platform.h
index 5a8f5a3..509fd58 100644
--- a/include/plat/common/platform.h
+++ b/include/plat/common/platform.h
@@ -390,5 +390,6 @@
 				       uintptr_t *dev_handle,
 				       uintptr_t *image_spec);
 void plat_fwu_set_images_source(const struct fwu_metadata *metadata);
+uint32_t plat_fwu_get_boot_idx(void);
 
 #endif /* PLATFORM_H */