diff --git a/docs/platform-interrupt-controller-API.rst b/docs/platform-interrupt-controller-API.rst
index 9ef2e3f..a94a90c 100644
--- a/docs/platform-interrupt-controller-API.rst
+++ b/docs/platform-interrupt-controller-API.rst
@@ -27,6 +27,45 @@
 In the case of ARM standard platforms using GIC, the *Running Priority Register*
 is read to determine the priority of the interrupt.
 
+Function: int plat_ic_is_spi(unsigned int id); [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Argument : unsigned int
+    Return   : int
+
+The API should return whether the interrupt ID (first parameter) is categorized
+as a Shared Peripheral Interrupt. Shared Peripheral Interrupts are typically
+associated to system-wide peripherals, and these interrupts can target any PE in
+the system.
+
+Function: int plat_ic_is_ppi(unsigned int id); [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Argument : unsigned int
+    Return   : int
+
+The API should return whether the interrupt ID (first parameter) is categorized
+as a Private Peripheral Interrupt. Private Peripheral Interrupts are typically
+associated with peripherals that are private to each PE. Interrupts from private
+peripherals target to that PE only.
+
+Function: int plat_ic_is_sgi(unsigned int id); [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+    Argument : unsigned int
+    Return   : int
+
+The API should return whether the interrupt ID (first parameter) is categorized
+as a Software Generated Interrupt. Software Generated Interrupts are raised by
+explicit programming by software, and are typically used in inter-PE
+communication. Secure SGIs are reserved for use by Secure world software.
+
 ----
 
 *Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.*