diff --git a/cereal/log.capnp b/cereal/log.capnp
index 6cf4781228aaa4..37ee2476f47d8b 100644
--- a/cereal/log.capnp
+++ b/cereal/log.capnp
@@ -414,6 +414,10 @@ struct CanData {
 struct DeviceState @0xa4d8b5af2aa492eb {
   deviceType @45 :InitData.DeviceType;
 
+  # usb
+  chestnutPresent @51 :Bool;
+  usbState @52 :UsbState;
+
   networkType @22 :NetworkType;
   networkInfo @31 :NetworkInfo;
   networkStrength @24 :NetworkStrength;
@@ -684,6 +688,26 @@ struct PeripheralState {
   }
 }
 
+struct UsbState {
+  vbusMv @0 :UInt32;
+  devices @1 :List(Device);
+
+  struct Device {
+    busnum @0 :UInt8;
+    devnum @1 :UInt8;
+    vendorId @2 :UInt16;
+    productId @3 :UInt16;
+    speedMbps @4 :UInt16;
+    product @5 :Text;
+    pmActive @6 :Bool;
+    runtimeSuspendedMs @7 :UInt64;
+
+    # error counters
+    overCurrentCount @8 :UInt32;
+    linkErrorCount @9 :UInt32;
+  }
+}
+
 struct RadarState @0x9a185389d6fdd05f {
   mdMonoTime @6 :UInt64;
   carStateMonoTime @11 :UInt64;
diff --git a/system/hardware/hardwared.py b/system/hardware/hardwared.py
index 5db73403e11f98..4c7a9e86a6942a 100755
--- a/system/hardware/hardwared.py
+++ b/system/hardware/hardwared.py
@@ -18,6 +18,7 @@
 from openpilot.common.realtime import DT_HW
 from openpilot.selfdrive.selfdrived.alertmanager import set_offroad_alert
 from openpilot.system.hardware import HARDWARE, TICI, AGNOS, PC
+from openpilot.system.hardware.usb import UsbLogger
 from openpilot.system.loggerd.config import get_available_percent
 from openpilot.system.statsd import statlog
 from openpilot.common.swaglog import cloudlog
@@ -153,6 +154,7 @@ def hardware_thread(end_event, hw_queue) -> None:
   pm = messaging.PubMaster(['deviceState'])
   sm = messaging.SubMaster(["peripheralState", "gpsLocationExternal", "selfdriveState", "pandaStates"], poll="pandaStates")
 
+  usb_logger = UsbLogger()
   count = 0
 
   onroad_conditions: dict[str, bool] = {
@@ -256,6 +258,11 @@ def hardware_thread(end_event, hw_queue) -> None:
 
     msg.deviceState.screenBrightnessPercent = HARDWARE.get_screen_brightness()
 
+    try:
+      usb_logger.update(msg.deviceState)
+    except Exception:
+      cloudlog.exception("usb_logger update failed")
+
     # this subset is only used for offroad
     temp_sources = [
       msg.deviceState.memoryTempC,
diff --git a/system/hardware/usb.py b/system/hardware/usb.py
new file mode 100644
index 00000000000000..5bd60caa31de3c
--- /dev/null
+++ b/system/hardware/usb.py
@@ -0,0 +1,90 @@
+from pathlib import Path
+
+from openpilot.common.swaglog import cloudlog
+from openpilot.selfdrive.modeld.helpers import USBGPU_VID, USBGPU_PID
+
+
+def read(path: Path) -> str | None:
+  try:
+    return path.read_text().strip()
+  except OSError:
+    return None
+
+
+def read_int(path: Path, base: int = 10) -> int:
+  s = read(path)
+  try:
+    return int(s, base) if s is not None else 0
+  except ValueError:
+    return 0
+
+
+def usb_devices() -> list[Path]:
+  # enumerated USB devices
+  devices = (d for d in Path("/sys/bus/usb/devices").glob("*") if (d / "idVendor").exists())
+  return sorted(devices, key=lambda p: p.name)
+
+
+def root_hub_port(device: Path) -> Path:
+  bus, _, port = device.name.partition("-")
+  return Path(f"/sys/bus/usb/devices/usb{bus}/{bus}-0:1.0/usb{bus}-port{port}")
+
+
+def controller(device: Path) -> Path | None:
+  # get SS port registers
+  for parent in device.resolve().parents:
+    if parent.name.endswith(".ssusb"):
+      return parent
+  return None
+
+
+class UsbLogger:
+  def __init__(self):
+    self.prev: set[tuple[int, int]] = set()
+
+  def update(self, device_state) -> None:
+    devices = usb_devices()
+
+    # low level state
+    state = device_state.usbState
+    state.vbusMv = read_int(Path("/sys/class/power_supply/usb/voltage_now")) // 1000
+    entries = state.init('devices', len(devices))
+
+    present: dict[tuple[int, int], Path] = {}
+    chestnut_present = False
+    for entry, device in zip(entries, devices, strict=True):
+      vendor_id = read_int(device / "idVendor", 16)
+      product_id = read_int(device / "idProduct", 16)
+      busnum = read_int(device / "busnum")
+      devnum = read_int(device / "devnum")
+      present[(busnum, devnum)] = device
+
+      entry.busnum = busnum
+      entry.devnum = devnum
+      entry.vendorId = vendor_id
+      entry.productId = product_id
+      entry.speedMbps = read_int(device / "speed")
+      entry.product = read(device / "product") or ""
+      entry.pmActive = read(device / "power/runtime_status") == "active"
+      entry.runtimeSuspendedMs = read_int(device / "power/runtime_suspended_time")
+      entry.overCurrentCount = read_int(root_hub_port(device) / "over_current_count")
+
+      ctrl = controller(device)
+      if ctrl is not None:
+        entry.linkErrorCount = read_int(ctrl / "portli", 0) & 0xFFFF  # decode PORTLI[15:0]
+
+      if (vendor_id, product_id) == (USBGPU_VID, USBGPU_PID):
+        chestnut_present = True
+
+    # parse peripherals
+    device_state.chestnutPresent = chestnut_present
+
+    # connect/disconnect events
+    for key in present.keys() - self.prev:
+      device = present[key]
+      cloudlog.event("usb_connected", busnum=key[0], devnum=key[1],
+                     vid=read(device / "idVendor"), pid=read(device / "idProduct"),
+                     speed=read(device / "speed"), product=read(device / "product"))
+    for key in self.prev - present.keys():
+      cloudlog.event("usb_disconnected", busnum=key[0], devnum=key[1])
+    self.prev = set(present)