Vendor Specific EL3 Monitor Service Calls
=========================================

This document enumerates and describes the Vendor Specific EL3 Monitor Service
Calls.

These are Service Calls defined by the vendor of the EL3 Monitor.
They are accessed via ``SMC`` ("SMC calls") instruction executed from Exception
Levels below EL3. SMC calls for Vendor Specific EL3 Monitor Services:

-  Follow `SMC Calling Convention`_;
-  Use SMC function IDs that fall in the vendor-specific EL3 range, which are

+---------------------------+--------------------------------------------------+
| SMC Function Identifier   | Service Type                                     |
+===========================+==================================================+
| 0x87000000 - 0x8700FFFF   | SMC32: Vendor Specific EL3 Monitor Service Calls |
+---------------------------+--------------------------------------------------+
| 0xC7000000 - 0xC700FFFF   | SMC64: Vendor Specific EL3 Monitor Service Calls |
+---------------------------+--------------------------------------------------+

Vendor-specific EL3 monitor services are as follows:

+-----------------------------------+-----------------------+---------------------------------------------+
| SMC Function Identifier           | Service Type          | FID's Usage                                 |
+===================================+=======================+=============================================+
| 0x87000010 - 0x8700001F (SMC32)   | DebugFS Interface     | | 0 - 11 are in use.                        |
+-----------------------------------+                       | | 12 - 15 are reserved for future expansion.|
| 0xC7000010 - 0xC700001F (SMC64)   |                       |                                             |
+-----------------------------------+-----------------------+---------------------------------------------+
| 0x87000020 - 0x8700002F (SMC32)   | Performance           | | 0 is in use.                              |
+-----------------------------------+ Measurement Framework | | 1 - 15 are reserved for future expansion. |
| 0xC7000020 - 0xC700002F (SMC64)   | (PMF)                 |                                             |
+-----------------------------------+-----------------------+---------------------------------------------+

Source definitions for vendor-specific EL3 Monitor Service Calls are located in
the ``ven_el3_svc.h`` header file.


Performance Measurement Framework (PMF)
---------------------------------------

The :ref:`Performance Measurement Framework <firmware_design_pmf>`
allows callers to retrieve timestamps captured at various paths in TF-A
execution.

DebugFS interface
-----------------

The optional DebugFS interface is accessed through Vendor specific EL3 service. Refer
to :ref:`DebugFS interface` documentation for further details and usage.

--------------

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.. _SMC Calling Convention: https://developer.arm.com/docs/den0028/latest