tools: add byd_can_dump.py — per-bus CAN address/rate dump for BYD bring-up

BYD Seal reports steering torque on 508 STEERING_TORQUE_ANGLE while the
Han uses 792 STEERING_TORQUE, and PCM_BUTTONS bus assignment is harness
dependent. This tool prints bus/addr/len/rate tables (with key BYD
addresses flagged) from either the latest recorded route (safe, no
hardware) or a live panda sniff (manager stopped).

tools/byd_can_dump.py

@@ -0,0 +1,142 @@
+#!/usr/bin/env python3
+"""BYD CAN bus dump — figures out which panda bus each BYD message is on.
+
+Usage (on the comma device, SSH'd in):
+
+  # Mode 1 (safest): analyze the most recent recorded route — no CAN hardware needed
+  cd /data/openpilot
+  python3 tools/byd_can_dump.py
+
+  # Mode 2: live sniff via panda (manager must be stopped first!)
+  tmux kill-server
+  python3 tools/byd_can_dump.py --live 15
+  # then reboot
+
+Key BYD addresses it highlights:
+  287 STEER_MODULE   289 ESC            482 MPC_LKAS_CMD_ANGLE
+  508 STEER_TORQUE_ANGLE               544 BRAKE_APPLIED
+  578 DRIVE_STATE    660 METER_CLUSTER  790 MPC_LKAS_CMD
+  792 STEERING_TORQUE                  813 ACC_HUD_ADAS
+  814 ACC_CMD        834 PEDAL          944 PCM_BUTTONS
+"""
+
+import argparse
+import os
+import time
+from collections import defaultdict
+
+KEY_ADDRS = {
+  287: "STEER_MODULE",
+  289: "ESC",
+  482: "MPC_LKAS_CMD_ANGLE",
+  508: "STEERING_TORQUE_ANGLE",
+  544: "BRAKE_APPLIED",
+  578: "DRIVE_STATE",
+  660: "METER_CLUSTER",
+  790: "MPC_LKAS_CMD",
+  792: "STEERING_TORQUE",
+  813: "ACC_HUD_ADAS",
+  814: "ACC_CMD",
+  834: "PEDAL",
+  944: "PCM_BUTTONS",
+}
+
+
+def print_table(stats, started_mono=None):
+  """stats: {(bus, addr): [len, count, first_t, last_t]}"""
+  buses = defaultdict(dict)
+  for (bus, addr), (length, count, first_t, last_t) in sorted(stats.items()):
+    buses[bus][addr] = (length, count, first_t, last_t)
+
+  for bus in sorted(buses):
+    print(f"\n=== bus {bus} ({len(buses[bus])} addresses) ===")
+    print(f"{'addr':>6}  {'len':>3}  {'count':>7}  {'rate_Hz':>7}  name")
+    for addr, (length, count, first_t, last_t) in sorted(buses[bus].items()):
+      dt = last_t - first_t
+      rate = (count - 1) / dt if dt > 0 and count > 1 else 0.0
+      name = KEY_ADDRS.get(addr, "")
+      marker = " <<<" if addr in KEY_ADDRS else ""
+      print(f"{addr:>6}  {length:>3}  {count:>7}  {rate:>7.1f}  {name}{marker}")
+
+
+def dump_from_route(route_dir=None):
+  from openpilot.tools.lib.logreader import LogReader
+
+  base = "/data/media/0/realdata"
+  if route_dir is None:
+    routes = sorted(d for d in os.listdir(base) if os.path.isdir(os.path.join(base, d)))
+    assert routes, f"no routes found in {base}"
+    route_dir = os.path.join(base, routes[-1])
+    print(f"using latest route: {route_dir}")
+
+  log_path = None
+  for name in ("rlog", "rlog.bz2", "rlog.zst", "qlog", "qlog.bz2", "qlog.zst"):
+    p = os.path.join(route_dir, name)
+    if os.path.exists(p):
+      log_path = p
+      break
+  assert log_path, f"no rlog/qlog found in {route_dir}"
+  print(f"reading {log_path} ...")
+
+  stats = {}
+  n_frames = 0
+  for m in LogReader(log_path):
+    if m.which() != "can":
+      continue
+    t = m.logMonoTime * 1e-9
+    for f in m.can:
+      if f.src >= 128:
+        continue
+      key = (f.src, f.address)
+      if key not in stats:
+        stats[key] = [len(f.dat), 0, t, t]
+      s = stats[key]
+      s[1] += 1
+      s[3] = t
+      n_frames += 1
+
+  print(f"{n_frames} CAN frames")
+  print_table(stats)
+
+
+def dump_live(seconds):
+  from panda import Panda
+  from opendbc.car.structs import CarParams
+
+  print("connecting to panda (manager must be stopped: tmux kill-server) ...")
+  p = Panda()
+  p.set_safety_mode(CarParams.SafetyModel.noOutput)
+  print(f"sniffing for {seconds}s ...")
+
+  stats = {}
+  t_end = time.monotonic() + seconds
+  t0 = time.monotonic()
+  n_frames = 0
+  while time.monotonic() < t_end:
+    for addr, dat, bus in p.can_recv():
+      if bus >= 128:
+        continue
+      t = time.monotonic() - t0
+      key = (bus, addr)
+      if key not in stats:
+        stats[key] = [len(dat), 0, t, t]
+      s = stats[key]
+      s[1] += 1
+      s[3] = t
+      n_frames += 1
+
+  print(f"{n_frames} CAN frames")
+  print_table(stats)
+
+
+if __name__ == "__main__":
+  ap = argparse.ArgumentParser()
+  ap.add_argument("--live", type=int, metavar="SECONDS", default=0,
+                  help="sniff live via panda for N seconds (stop manager first!)")
+  ap.add_argument("--route", type=str, default=None, help="route dir to analyze instead of latest")
+  args = ap.parse_args()
+
+  if args.live:
+    dump_live(args.live)
+  else:
+    dump_from_route(args.route)