docs(zynqmp): update SMC convention

Updated documentation for SMC SiP calling conventions for IPI,
PM, and SiP Service queries.

Signed-off-by: Prasad Kummari <prasad.kummari@amd.com>
Change-Id: I8904628d41b47596257f06791bffb7cde35879de

docs/plat/xilinx-zynqmp.rst

@@ -166,3 +166,55 @@ Custom package makefile fragment inclusion in TF-A build
 - TF-A build command:
   make CROSS_COMPILE=aarch64-none-elf- PLAT=zynqmp RESET_TO_BL31=1
   bl31 CUSTOM_PKG_PATH=<...>
+
+Reference DEN0028E SMC calling convention
+------------------------------------------
+
+Allocated subranges of Function Identifier to SIP services
+------------------------------------------------------------
+
++-----------------------+-------------------------------------------------------+
+|    SMC Function       | Identifier Service type                               |
++-----------------------+-------------------------------------------------------+
+| 0xC2000000-0xC200FFFF | Fast SMC64 SiP Service Calls as per SMCCC Section 6.1 |
++-----------------------+-------------------------------------------------------+
+
+IPI SMC call ranges
+-------------------
+
++---------------------------+-----------------------------------------------------------+
+| SMC Function Identifier   | Service type                                              |
++---------------------------+-----------------------------------------------------------+
+| 0xc2001000-0xc2001FFF     | Fast SMC64 SiP Service call range used for AMD-Xilinx IPI |
++---------------------------+-----------------------------------------------------------+
+
+PM SMC call ranges
+------------------
+
++---------------------------+---------------------------------------------------------------------------+
+| SMC Function Identifier   |  Service type                                                             |
++---------------------------+---------------------------------------------------------------------------+
+| 0xc2000000-0xc2000FFF     | Fast SMC64 SiP Service call range used for AMD-Xilinx Platform Management |
++---------------------------+---------------------------------------------------------------------------+
+
+SMC function IDs for SiP Service queries
+----------------------------------------
+
++--------------+--------------+--------------+
+|  Service     | Call UID     | Revision     |
++--------------+--------------+--------------+
+|  SiP Service | 0x8200_FF01  | 0x8200_FF03  |
++--------------+--------------+--------------+
+
+Call UID Query – Returns a unique identifier of the service provider.
+
+Revision Query – Returns revision details of the service implementor.
+
+CUSTOM SIP service support
+--------------------------
+
++-------------+------------+------------+
+| Service     | 32-bit     | 64-bit     |
++-------------+------------+------------+
+| SiP Service | 0x82002000 | 0xC2002000 |
++-------------+------------+------------+