doc: Update memory layout for firmware configuration area

Captured the increase in firmware configuration area from
4KB to 8kB in memory layout document. Updated the documentation
to provide details about fw_config separately.
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Ifbec443ced479301be65827b49ff4fe447e9109f

docs/design/firmware-design.rst

@@ -83,6 +83,10 @@ Each of the Boot Loader stages may be dynamically configured if required by the
 platform. The Boot Loader stage may optionally specify a firmware
 configuration file and/or hardware configuration file as listed below:
 
+-  FW_CONFIG - The firmware configuration file. Holds properties shared across
+   all BLx images.
+   An example is the "dtb-registry" node, which contains the information about
+   the other device tree configurations (load-address, size, image_id).
 -  HW_CONFIG - The hardware configuration file. Can be shared by all Boot Loader
    stages and also by the Normal World Rich OS.
 -  TB_FW_CONFIG - Trusted Boot Firmware configuration file. Shared between BL1
@@ -109,8 +113,8 @@ convention:
    the generic hardware configuration is passed the next available argument.
    For example,
 
-   -  If TB_FW_CONFIG is loaded by BL1, then its address is passed in ``arg0``
-      to BL2.
+   -  FW_CONFIG is loaded by BL1, then its address is passed in ``arg0`` to BL2.
+   -  TB_FW_CONFIG address is retrieved by BL2 from FW_CONFIG device tree.
    -  If HW_CONFIG is loaded by BL1, then its address is passed in ``arg2`` to
       BL2. Note, ``arg1`` is already used for meminfo_t.
    -  If SOC_FW_CONFIG is loaded by BL2, then its address is passed in ``arg1``
@@ -1732,7 +1736,7 @@ CONFIG section in memory layouts shown below contains:
 ``bl2_mem_params_descs`` contains parameters passed from BL2 to next the
 BL image during boot.
 
-``fw_configs`` includes soc_fw_config, tos_fw_config and tb_fw_config.
+``fw_configs`` includes soc_fw_config, tos_fw_config, tb_fw_config and fw_config.
 
 **FVP with TSP in Trusted SRAM with firmware configs :**
 (These diagrams only cover the AArch64 case)
@@ -1757,7 +1761,7 @@ BL image during boot.
                |          |  <<<<<<<<<<<<<  | BL31 PROGBITS  |
                |          |  <<<<<<<<<<<<<  |----------------|
                |          |  <<<<<<<<<<<<<  |     BL32       |
-    0x04002000 +----------+                 +----------------+
+    0x04003000 +----------+                 +----------------+
                |  CONFIG  |
     0x04001000 +----------+
                |  Shared  |
@@ -1794,7 +1798,7 @@ BL image during boot.
                |--------------|  <<<<<<<<<<<<<  |----------------|
                |              |  <<<<<<<<<<<<<  | BL31 PROGBITS  |
                |              |                 +----------------+
-               +--------------+
+    0x04003000 +--------------+
                |    CONFIG    |
     0x04001000 +--------------+
                |    Shared    |
@@ -1828,7 +1832,7 @@ BL image during boot.
                |----------|  <<<<<<<<<<<<<  |----------------|
                |          |  <<<<<<<<<<<<<  | BL31 PROGBITS  |
                |          |                 +----------------+
-    0x04002000 +----------+
+    0x04003000 +----------+
                |  CONFIG  |
     0x04001000 +----------+
                |  Shared  |