swim: add new transport

Add SWIM and STM8 to documentation and update TODO file.
Introduce transport "swim" and command "swim newtap".
Switch in swim.c from HLA API to the new SWIM API.
Implement in stlink driver the SWIM APIs as wrappers of existing
HLA functions.
Remove any SWIM related reference from HLA files.
Update stm8 config files and stlink-dap interface config file.

Change-Id: I2bb9f58d52900f6eb4df05f979f7ef11fd439c24
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5530
Tested-by: jenkins

doc/openocd.texi

@@ -3304,6 +3304,24 @@ The Serial Peripheral Interface (SPI) is a general purpose transport
 which uses four wire signaling. Some processors use it as part of a
 solution for flash programming.
 
+@anchor{swimtransport}
+@subsection SWIM Transport
+@cindex SWIM
+@cindex Single Wire Interface Module
+The Single Wire Interface Module (SWIM) is a low-pin-count debug protocol used
+by the STMicroelectronics MCU family STM8 and documented in the
+@uref{https://www.st.com/resource/en/user_manual/cd00173911.pdf, User Manual UM470}.
+
+SWIM does not support boundary scan testing nor multiple cores.
+
+The SWIM transport is selected with the command @command{transport select swim}.
+
+The concept of TAPs does not fit in the protocol since SWIM does not implement
+a scan chain. Nevertheless, the current SW model of OpenOCD requires defining a
+virtual SWIM TAP through the command @command{swim newtap basename tap_type}.
+The TAP definition must precede the target definition command
+@command{target create target_name stm8 -chain-position basename.tap_type}.
+
 @anchor{jtagspeed}
 @section JTAG Speed
 JTAG clock setup is part of system setup.
@@ -9831,6 +9849,12 @@ This command is similar to @command{arc jtag get-aux-reg} but is for core
 registers.
 @end deffn
 
+@section STM8 Architecture
+@uref{http://st.com/stm8/, STM8} is a 8-bit microcontroller platform from
+STMicroelectronics, based on a proprietary 8-bit core architecture.
+
+OpenOCD supports debugging STM8 through the STMicroelectronics debug
+protocol SWIM, @pxref{swimtransport,,SWIM}.
 
 @anchor{softwaredebugmessagesandtracing}
 @section Software Debug Messages and Tracing