feat(memmap): add topological memory view

Present memory usage in hierarchical view. This view maps modules to
their respective segments and sections.

Change-Id: I5c374b46738edbc83133441ff3f4268f08cb011d
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/docs/tools/memory-layout-tool.rst b/docs/tools/memory-layout-tool.rst
index ff5188e..8874bd7 100644
--- a/docs/tools/memory-layout-tool.rst
+++ b/docs/tools/memory-layout-tool.rst
@@ -147,6 +147,88 @@
 The script relies on symbols in the symbol table to determine the start, end,
 and limit addresses of each bootloader stage.
 
+Memory Tree
+~~~~~~~~~~~
+
+A hierarchical view of the memory layout can be produced by passing the option
+``-t`` or ``--tree`` to the tool. This gives the start, end, and size of each
+module, their ELF segments as well as sections.
+
+.. code:: shell
+
+    $ poetry run memory -t
+    build-path: build/fvp/release
+    name                                       start        end       size
+    bl1                                            0    400c000    400c000
+    ├── 00                                         0       5de0       5de0
+    │   ├── .text                                  0       5000       5000
+    │   └── .rodata                             5000       5de0        de0
+    ├── 01                                   4034000    40344c5        4c5
+    │   └── .data                            4034000    40344c5        4c5
+    ├── 02                                   4034500    4034a00        500
+    │   └── .stacks                          4034500    4034a00        500
+    ├── 04                                   4034a00    4035600        c00
+    │   └── .bss                             4034a00    4035600        c00
+    └── 03                                   4036000    403b000       5000
+        └── .xlat_table                      4036000    403b000       5000
+    bl2                                      4021000    4034000      13000
+    ├── 00                                   4021000    4027000       6000
+    │   ├── .text                            4021000    4026000       5000
+    │   └── .rodata                          4026000    4027000       1000
+    └── 01                                   4027000    402e000       7000
+        ├── .data                            4027000    4027809        809
+        ├── .stacks                          4027840    4027e40        600
+        ├── .bss                             4028000    4028800        800
+        └── .xlat_table                      4029000    402e000       5000
+    bl2u                                     4021000    4034000      13000
+    ├── 00                                   4021000    4025000       4000
+    │   ├── .text                            4021000    4024000       3000
+    │   └── .rodata                          4024000    4025000       1000
+    └── 01                                   4025000    402b000       6000
+        ├── .data                            4025000    4025065         65
+        ├── .stacks                          4025080    4025480        400
+        ├── .bss                             4025600    4025c00        600
+        └── .xlat_table                      4026000    402b000       5000
+    bl31                                     4003000    4040000      3d000
+    ├── 02                                  ffe00000   ffe03000       3000
+    │   └── .el3_tzc_dram                   ffe00000   ffe03000       3000
+    ├── 00                                   4003000    4010000       d000
+    │   └── .text                            4003000    4010000       d000
+    └── 01                                   4010000    4021000      11000
+        ├── .rodata                          4010000    4012000       2000
+        ├── .data                            4012000    401219d        19d
+        ├── .stacks                          40121c0    40161c0       4000
+        ├── .bss                             4016200    4018c00       2a00
+        ├── .xlat_table                      4019000    4020000       7000
+        └── .coherent_ram                    4020000    4021000       1000
+
+
+The granularity of this view can be modified with the ``--depth`` option. For
+instance, if you only require the tree up to the level showing segment data,
+you can specify the depth with:
+
+.. code::
+
+    $ poetry run memory -t --depth 2
+    build-path: build/fvp/release
+    name                          start        end       size
+    bl1                               0    400c000    400c000
+    ├── 00                            0       5df0       5df0
+    ├── 01                      4034000    40344c5        4c5
+    ├── 02                      4034500    4034a00        500
+    ├── 04                      4034a00    4035600        c00
+    └── 03                      4036000    403b000       5000
+    bl2                         4021000    4034000      13000
+    ├── 00                      4021000    4027000       6000
+    └── 01                      4027000    402e000       7000
+    bl2u                        4021000    4034000      13000
+    ├── 00                      4021000    4025000       4000
+    └── 01                      4025000    402b000       6000
+    bl31                        4003000    4040000      3d000
+    ├── 02                     ffe00000   ffe03000       3000
+    ├── 00                      4003000    4010000       d000
+    └── 01                      4010000    4021000      11000
+
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