connect all the jtag pins and connect PU_CHIP pin to nReset/srst/sreset of the ftdi jtag adapter/rv debugger plus
and use the bellow config
pine64jtag.cfg
interface ftdi
#may need to change this to your adapters vid and pid
ftdi_vid_pid 0x0403 0x6014
ftdi_channel 0
transport select jtag
adapter_khz 4000
ftdi_layout_init 0x00f8 0x00fb
ftdi layout_signal nSRST -data 0x0020 -oe 0x0020
adapter_nsrst_delay 8
tgt_e907.cfg
set _CHIPNAME riscv
jtag newtap $_CHIPNAME cpu -irlen 5 -expected-id 0x10000b6f
set _TARGETNAME $_CHIPNAME.cpu
target create $_TARGETNAME.0 riscv -chain-position $_TARGETNAME
$_TARGETNAME.0 configure -work-area-phys 0x40000000 -work-area-size 0x10000 -work-area-backup 0
echo "Ready for Remote Connections"
gdb_memory_map enable
gdb_flash_program disable
riscv set_prefer_sba off
reset_config srst_only srst_pulls_trst
riscv set_command_timeout_sec 3
init
then
openocd -f pine64jtag.cfg -f tgt_e907.cfg
in gdb
target extended-remote :3333
monitor reset init
monitor gdb_sync
si
PC should be somewhere in bootrom.
if you get bellow error, increase adapter_nsrst_delay
JTAG scan chain interrogation failed: all ones
Check JTAG interface, timings, target power, etc.
Trying to use configured scan chain anyway...
Bypassing JTAG setup events due to errors
This will work too
tgt_e907.cfg