This adds the guts of a transport framework with initialization,
which should work with current JTAG-only configurations (tested
with FT2232).
Each debug adapter can declare the transports it supports, and
exactly one transport is initialized. (with its commands) in
any given OpenOCD session.
* Define a new "struct transport with init hooks and a few
"transport" subcommands to support it:
"list" ... list the transports configured (just "jtag" for now)
"select" ... makes the debug session use that transport
"init" ... initializes the selected transport (internal)
* "interface_transports" ... declares transports the current interface
can support. (Some will do this from C code instead, when there are
no hardware versioning (or other) issues to prevent it.
Plus some FT2232 tweaks, including a few to streamline upcoming
support for an SWD transport (initially for Luminary adapters).
Eventually src/jtag should probably become src/transport, moving
jtag-specific stuff to transport/jtag.
Signed-off-by: David Brownell <db@helium.(none)>
93f2afa45f