doc: Add doc for supported chipsets

Change-Id: I9c9edc7deeeb7a783e2ba2fc6b372edb9c61609e
Signed-off-by: Anastasia Klimchuk <aklm@flashrom.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/82198
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Peter Marheine <pmarheine@chromium.org>

doc/supported_hw/index.rst

@@ -7,3 +7,4 @@ Supported hardware
 
     supported_flashchips
     supported_prog/index
+    supported_chipsets

doc/supported_hw/supported_chipsets.rst

@@ -0,0 +1,21 @@
+==================
+Supported chipsets
+==================
+
+To see the list of all supported chipsets, check the ``const struct penable chipset_enables[]`` in ``chipset_enable.c`` file in the source tree.
+If you have a flashrom repo cloned locally, you can look at the file in your repo.
+
+Alternatively inspect the file `on the web UI of our GitHub mirror <https://github.com/flashrom/flashrom/blob/main/chipset_enable.c#L1768>`_.
+
+If you can run flashrom locally, the command ``flashrom -L`` prints the list of all supported chipsets
+(see :doc:`/classic_cli_manpage` for more details on command line options). The output of this command is long, so you might
+want to save it to file or grep.
+
+Each chipset entry is described by ``struct penable`` in ``include/programmer.h`` which you can inspect in the same way, either in the local source tree or
+`in the GitHub web UI <https://github.com/flashrom/flashrom/blob/main/include/programmer.h#L149>`_.
+
+Note the ``enum test_state status`` of the chipset. ``OK`` means chipset is tested, ``NT`` means not tested, to see all possible
+test states check the ``enum test_state`` definition in ``include/flash.h``.
+
+Also note that macros for supported buses are defined in ``chipset_enable.c`` right before ``chipset_enables[]`` array.
+For example ``B_S`` means ``BUS_SPI``, check the ``chipset_enable.c`` source code for the rest of macro definitions.