• 目前在FPGA上已经测出来，已能支持32个tap，
• autotap 推定可以到16个，再多的话，需要把工具自己推出来的写成定义tap

jtag_rest 1 0               -- 复位，tck和TMS组合而成，如果有trstn的话，则产生trstn
irscan zynq.dap 0x5         -- 往tap寄存器写IR指令为0x5,   TAP在target.cfg文件中进行定义（jtag newtap）
drscan zynq.dap 16 0x4321   -- 向指定TAP输入DR数据，长度为16，数据为0x4321

• 注意，一定要先指定TAP IR, 然后才可以向 DR进行输入数据，不然openocd会报错退出。
• openocd使用tcl语法进行配置，可以使用telnet进行连接

ft2232h.cfg

#####################################
#
# Layout:  FTDI FT2232H example
#   ADBUS0 TCK
#   ADBUS1 TDI
#   ADBUS2 TDO (input)
#   ADBUS3 TMS
#   ADBUS4 nTRST
#   ADBUS5 nSRST
#   ADBUS6 OE (active high) for TRST, TDI, TMS, TCK
#   ADBUS7 DBGREQ_L
 
 
interface ftdi
ftdi_vid_pid 0x0403 0x6010
ftdi_channel 0

###### interface config 0
# just TCK TDI TDO TMS
# ftdi_layout_init 0x0008 0x000b

###### interface config 1
# ADBUS6 no used
ftdi_layout_init 0x0098 0x00bb; # initial data, port direction (1-out, 0-in)
ftdi_layout_signal nTRST    -data 0x0010 -input 0x0010
ftdi_layout_signal nSRST    -data 0x0020 -input 0x0020
ftdi_layout_signal DBGREQ_L -data 0x0080 -input 0x0080

 
# -data   can drive to  1 & 0
# -oe     can only drive to 0 / high-z, can't drive 1
# -input  can use cmd ftdi_get_signal to get signal value

target.cfg

set _CHIPNAME zynq
jtag newtap $_CHIPNAME  dap -irlen 8 -ircapture 0x01 -irmask 0x03
 
adapter_khz 5000

# gdb_port    3333
# tcl_port    6666
# telnet_port 4444

sudo openocd  -f ft2232h.cfg  -f target.cfg

OpenOCD provides a simple RPC server that allows to run arbitrary Tcl commands and
receive the results.
To access it, your application needs to connect to a configured TCP port (see tcl_port).
Then it can pass any string to the interpreter terminating it with 0x1a and wait for the
return value (it will be terminated with 0x1a as well). This can be repeated as many times
as desired without reopening the connection.
Remember that most of the OpenOCD commands need to be prefixed with ocd_ to get the
results back. Sometimes you might also need the capture command.
See contrib/rpc_examples/ for specific client implementations.

可以参考openocd包目录contrib/rpc_examples/下的例子。