OpenOCD remote bitbang stub for SC8810 DSP MMIO JTAG
HACK: Build as static to run on Android
arm-linux-gnueabihf-gcc remote_bitbang_sc8810_djtag.c -static -o remote_bitbang_sc8810_djtag
Note: Your GCC version might be too new for downstream Android kernel. Use GCC 4.x
Install busybox on Android, then push remote_bitbang_sc8810_djtag to somewhere executable(not /sdcard), then run it:
adb push remote_bitbang_sc8810_djtag /data/local/tmp
adb shell
> su
> cd /data/local/tmp
> chmod 755 remote_bitbang_sc8810_djtag
> busybox nc -l -p 7777 -e ./remote_bitbang_sc8810_djtag
Run openocd on host:
openocd -c "adapter driver remote_bitbang; remote_bitbang_host <device ip address>; remote_bitbang_port 7777" -c "jtag newtap dsp tap -irlen 32 -expected-id 0x016224a5"
Connect to openocd:
telnet 127.0.0.1 4444
As there's (apparently) no CEVA-X1622 support in current OpenOCD, only raw JTAG operations can be performed:
Read core version(?):
> irscan dsp.tap 0x72000000
> drscan dsp.tap 32 0
16220401
>
Read PC value:
> irscan dsp.tap 0x34000000
> drscan dsp.tap 32 0
c00a87d8
>
Note that it seems only the uppermost 8bits of IR is used.