Replace Board Vendor and Name with UUID for board identification purposes

[madchutney]

CMSIS DAP_Info (v2.1) fields (Target Board Vendor and Target Board Name) can currently be used to identify a board and map it to a board definition in a CMSIS pack (if provided by the board firmware).

It is proposed that:

• A Target Board ID field is added to the DAP_Info fields.
• The Target Board ID is a UUID.
• The use of Target Board Vendor and Target Board Name is deprecated for programmatic board identification purposes.
• The PDSC schema is extended so that the same Target Board ID can be added to the CMSIS pack board definition.

This proposal has several advantages:

• It uses a decentralised approach, whereby a UUID can be generated (by a vendor).
• UUIDs are well known and well supported, with generation tools almost ubiquitous.
• It is a simple and direct method of linking board firmware to a board definition in a CMSIS pack.
• The board ID is decoupled from the human readable name.
• Board revisions can be easily mapped to new pack definitions by the introduction of a new UUID, and without any need to change the human readable board name. This is a limitation in the current system, where the board revision cannot be identified via the DAP_Info fields.

[flit]

Adding a UUID would be fine and quite handy in certain situations (I fully support the addition), but it must not be a replacement for Target Board Vendor and Target Board Name. Those are necessary for situations where there is not a CMSIS-Pack board definitions—which is most existing boards.

Example: The micro:bit boards use Target Board Vendor and Target Board Name in their on-board DAPLink firmware, but there will probably not be a micro:bit CMSIS-Pack with board definitions any time soon.

Target Board Vendor and Target Board Name are also immensely useful to present user visible information about a connect board without needing a whole CMSIS Pack database already installed.

We must keep in mind the vast usage of CMSIS DAP outside the realm of CMSIS Packs.

Regarding board revisions, we need to also add a Target Board Revision DAP_info key. This can be user visible, as well as being used for programmatic purposes when there is not a CMSIS Pack for the board.