[microTVM] Zephyr: refactor _find_openocd_serial_port (#10346)

Refactor _find_openocd_serial_port() as a generic USB serial port
finder since other runners beyond openocd use it (e.g. jlink runner).

Also instead of using redundant hardcoded values in BOARD_USB_FIND_KW
dict, use idVendor and idProduct from boards.json. And don't use 'usb'
module to first find the serial number of the port and then pass it to
'serial' module to obtain the port path, instead search for the port
path directly via 'serial' module using the serial number (if provided)
or use idVendor and idProduct values taken from boards.json.

Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>

apps/microtvm/zephyr/template_project/boards.json

@@ -4,8 +4,8 @@
         "model": "imxrt10xx",
         "is_qemu": false,
         "fpu": true,
-        "vid_hex": "",
-        "pid_hex": ""
+        "vid_hex": "1366",
+        "pid_hex": "0105"
     },
     "mps2_an521": {
         "board": "mps2_an521",

apps/microtvm/zephyr/template_project/microtvm_api_server.py

@@ -166,38 +166,47 @@ def _get_device_args(options):
     )
 
 
-# kwargs passed to usb.core.find to find attached boards for the openocd flash runner.
-BOARD_USB_FIND_KW = {
-    "nucleo_l4r5zi": {"idVendor": 0x0483, "idProduct": 0x374B},
-    "nucleo_f746zg": {"idVendor": 0x0483, "idProduct": 0x374B},
-    "stm32f746g_disco": {"idVendor": 0x0483, "idProduct": 0x374B},
-    "mimxrt1050_evk": {"idVendor": 0x1366, "idProduct": 0x0105},
-}
+def generic_find_serial_port(serial_number=None):
+    """Find a USB serial port based on its serial number or its VID:PID.
 
+    This method finds a USB serial port device path based on the port's serial number (if given) or
+    based on the board's idVendor and idProduct ids.
 
-def openocd_serial(options):
-    """Find the serial port to use for a board with OpenOCD flash strategy."""
-    if "openocd_serial" in options:
-        return options["openocd_serial"]
+    Parameters
+    ----------
+    serial_number : str
+        The serial number associated to the USB serial port which the board is attached to. This is
+        the same number as shown by 'lsusb -v' in the iSerial field.
 
-    find_kw = BOARD_USB_FIND_KW[CMAKE_CACHE["BOARD"]]
-    boards = usb.core.find(find_all=True, **find_kw)
-    serials = []
-    for b in boards:
-        serials.append(b.serial_number)
+    Returns
+    -------
+    Path to the USB serial port device, for example /dev/ttyACM1.
+    """
+    if serial_number:
+        regex = serial_number
+    else:
+        prop = BOARD_PROPERTIES[CMAKE_CACHE["BOARD"]]
+        device_id = ":".join([prop["vid_hex"], prop["pid_hex"]])
+        regex = device_id
 
-    if len(serials) == 0:
-        raise BoardAutodetectFailed(f"No attached USB devices matching: {find_kw!r}")
-    serials.sort()
+    serial_ports = list(serial.tools.list_ports.grep(regex))
 
-    autodetected_openocd_serial = serials[0]
-    _LOG.debug("zephyr openocd driver: autodetected serial %s", serials[0])
+    if len(serial_ports) == 0:
+        raise Exception(f"No serial port found for board {prop['board']}!")
 
-    return autodetected_openocd_serial
+    if len(serial_ports) != 1:
+        ports_lst = ""
+        for port in serial_ports:
+            ports_lst += f"Serial port: {port.device}, serial number: {port.serial_number}\n"
+
+        raise Exception("Expected 1 serial port, found multiple ports:\n {ports_lst}")
+
+    return serial_ports[0].device
 
 
 def _get_openocd_device_args(options):
-    return ["--serial", openocd_serial(options)]
+    serial_number = options.get("openocd_serial")
+    return ["--serial", generic_find_serial_port(serial_number)]
 
 
 def _get_nrf_device_args(options):
@@ -645,19 +654,12 @@ def _find_nrf_serial_port(cls, options):
 
     @classmethod
     def _find_openocd_serial_port(cls, options):
-        serial_number = openocd_serial(options)
-        ports = [p for p in serial.tools.list_ports.grep(serial_number)]
-        if len(ports) != 1:
-            raise Exception(
-                f"_find_openocd_serial_port: expected 1 port to match {serial_number}, "
-                f"found: {ports!r}"
-            )
-
-        return ports[0].device
+        serial_number = options.get("openocd_serial")
+        return generic_find_serial_port(serial_number)
 
     @classmethod
     def _find_jlink_serial_port(cls, options):
-        return cls._find_openocd_serial_port(options)
+        return generic_find_serial_port()
 
     @classmethod
     def _find_serial_port(cls, options):