Probably you already used the two wires SWD interface with some ARM Cortex MCU, but this interface is proprietary, ARM has patent and rights over it. Fortunately exists an alternative called cJTAG.

cJTAG is not well supported by open-source solutions like OpenOCD (the “support” it forcing the chip to fallback to 4 wires). Today I tested cJTAG using a J-Link Base probe on Linux and it worked fine:

$ sudo JLinkExe -if cjtag -device CC2640R2F
[sudo] password for alan:
SEGGER J-Link Commander V6.80d (Compiled Jun 26 2020 17:19:52)
DLL version V6.80d, compiled Jun 26 2020 17:19:40

Connecting to J-Link via USB…Updating firmware: J-Link V11 compiled Jun 9 2020 13:38:27
Replacing firmware: J-Link V11 compiled Jan 7 2020 16:52:13
Waiting for new firmware to boot
New firmware booted successfully
O.K.
Firmware: J-Link V11 compiled Jun 9 2020 13:38:27
Hardware version: V11.00
S/N: 51000000
License(s): GDB
VTref=3.044V

Type "connect" to establish a target connection, '?' for help
J-Link>connect
Device position in JTAG chain (IRPre,DRPre) : -1,-1 => Auto-detect
JTAGConf>
Specify target interface speed [kHz]. : 4000 kHz
Speed>
Device "CC2640R2F" selected.

Connecting to target via cJTAG
InitTarget: Found ICE-Pick with ID: 0xBB99A02F
InitTarget: Can not find CPU TAP (IDCODE mismatch. Expected 0x00000477, found: 0xFFFFFFFF
InitTarget: Found ICE-Pick with ID: 0xBB99A02F
InitTarget: Found CPU TAP 0x4BA00477
Failed to power up DAP
InitTarget: Found ICE-Pick with ID: 0xBB99A02F
InitTarget: Can not find CPU TAP (IDCODE mismatch. Expected 0x00000477, found: 0x00000000
InitTarget: Found ICE-Pick with ID: 0xBB99A02F
InitTarget: Found CPU TAP 0x4BA00477
Cannot determine DP version. Assuming DPv0
Scanning AP map to find all available APs
AP[1]: Stopped AP scan as end of AP map has been reached
AP[0]: AHB-AP (IDR: 0x24770011)
Iterating through AP map to find AHB-AP to use
AP[0]: Core found
AP[0]: AHB-AP ROM base: 0xE00FF000
CPUID register: 0x412FC231. Implementer code: 0x41 (ARM)
Found Cortex-M3 r2p1, Little endian.
FPUnit: 6 code (BP) slots and 2 literal slots
CoreSight components:
ROMTbl[0] @ E00FF000
ROMTbl[0][0]: E000E000, CID: B105E00D, PID: 000BB000 SCS
ROMTbl[0][1]: E0001000, CID: B105E00D, PID: 003BB002 DWT
ROMTbl[0][2]: E0002000, CID: B105E00D, PID: 002BB003 FPB
ROMTbl[0][3]: E0000000, CID: B105E00D, PID: 003BB001 ITM
ROMTbl[0][4]: E0040000, CID: B105900D, PID: 003BB923 TPIU-Lite
Cortex-M3 identified.

J-Link> savebin fw.bin 0x00000000 0x20000
Opening binary file for writing... [fw.bin]
Reading 131072 bytes from addr 0x00000000 into file...
O.K.
J-Link>