[serial_proxy] Add USB identity query for USB-bridged ports

Add SERIAL_PROXY_PORT_TYPE_USB_SERIAL, derived automatically when a
port's uart_id resolves to a usb_uart channel (never set by the user),
and a SerialProxyGetUsbInfoRequest/Response pair (IDs 153/154) that
reads VID/PID/bcdDevice and the manufacturer/product/serial strings
live from the descriptors the USB host stack caches, so a client can
identify the attached device before subscribing. Ports that are not
USB_SERIAL answer NOT_SUPPORTED; an unplugged device answers with
connected=false. ZigbeeProxyRequest moves to ID 155 (expected merge
order: set_mode, USB info, zigbee).

esphome/components/api/api.proto

@@ -78,6 +78,7 @@ service APIConnection {
   rpc serial_proxy_write(SerialProxyWriteRequest) returns (void) {}
   rpc serial_proxy_set_modem_pins(SerialProxySetModemPinsRequest) returns (void) {}
   rpc serial_proxy_get_modem_pins(SerialProxyGetModemPinsRequest) returns (void) {}
+  rpc serial_proxy_get_usb_info(SerialProxyGetUsbInfoRequest) returns (void) {}
   rpc serial_proxy_request(SerialProxyRequest) returns (void) {}
   rpc serial_proxy_set_mode(SerialProxySetModeRequest) returns (void) {}
 }
@@ -230,6 +231,11 @@ enum SerialProxyPortType {
   SERIAL_PROXY_PORT_TYPE_TTL = 0;
   SERIAL_PROXY_PORT_TYPE_RS232 = 1;
   SERIAL_PROXY_PORT_TYPE_RS485 = 2;
+  // A serial device attached through a USB bridge. Set by the device configuration, never
+  // by the user; identifies ports whose USB identity can be read with
+  // SerialProxyGetUsbInfoRequest. Deliberately not a USB endpoint type: serial_proxy
+  // carries serial devices only, whatever bridge chip connects them.
+  SERIAL_PROXY_PORT_TYPE_USB_SERIAL = 3;
 }
 
 message SerialProxyInfo {
@@ -2873,6 +2879,36 @@ message SerialProxySetModeRequest {
   SerialProxyMode mode = 2;
 }
 
+// Ask for the USB identity of the device behind a USB_SERIAL port. Read-only, so no
+// subscription is required -- a client typically uses this to decide which port to
+// subscribe to. Answered with NOT_SUPPORTED on ports that are not USB_SERIAL.
+message SerialProxyGetUsbInfoRequest {
+  option (id) = 153;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;
+}
+
+// The USB identity of the device currently behind a port, read live from the cached
+// USB descriptors. Fields are zero/empty while no device is connected.
+message SerialProxyGetUsbInfoResponse {
+  option (id) = 154;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;
+  SerialProxyStatus status = 2;   // NOT_SUPPORTED when the port is not USB_SERIAL
+  bool connected = 3;             // True when a USB device is currently attached
+  uint32 vendor_id = 4;
+  uint32 product_id = 5;
+  uint32 bcd_device = 6;
+  uint32 interface_number = 7;    // Channel index on multi-port bridges
+  string manufacturer = 8;
+  string product = 9;
+  string serial_number = 10;
+}
+
 // ==================== BLUETOOTH CONNECTION PARAMS ====================
 message BluetoothSetConnectionParamsRequest {
   option (id) = 145;
@@ -2902,7 +2938,7 @@ enum ZigbeeProxyRequestType {
 }
 
 message ZigbeeProxyRequest {
-  option (id) = 153;
+  option (id) = 155;
   option (source) = SOURCE_BOTH;
   option (ifdef) = "USE_ZIGBEE_PROXY";
 

esphome/components/api/api_connection.cpp

@@ -51,6 +51,9 @@
 #ifdef USE_ZIGBEE_PROXY
 #include "esphome/components/zigbee_proxy/zigbee_proxy.h"
 #endif
+#ifdef USE_SERIAL_PROXY_USB_INFO
+#include "esphome/components/usb_host/usb_host.h"
+#endif
 #ifdef USE_WATER_HEATER
 #include "esphome/components/water_heater/water_heater.h"
 #endif
@@ -1651,6 +1654,27 @@ void APIConnection::on_serial_proxy_get_modem_pins_request(const SerialProxyGetM
   }
 }
 
+void APIConnection::on_serial_proxy_get_usb_info_request(const SerialProxyGetUsbInfoRequest &msg) {
+  auto &proxies = App.get_serial_proxies();
+  SerialProxyGetUsbInfoResponse resp{};
+  resp.instance = msg.instance;
+  if (msg.instance >= proxies.size()) {
+    ESP_LOGW(TAG, "Serial proxy instance %" PRIu32 " out of range", msg.instance);
+    resp.status = enums::SERIAL_PROXY_STATUS_INVALID_ARGUMENT;
+  } else {
+#ifdef USE_SERIAL_PROXY_USB_INFO
+    // The response's strings are views into this buffer, which outlives the send below
+    usb_host::UsbDeviceInfo info;
+    proxies[msg.instance]->get_usb_info(info, resp);
+#else
+    resp.status = enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED;
+#endif
+  }
+  if (!this->send_message(resp)) {
+    API_LOG_MSG_DROPPED(TAG, "Serial proxy response");
+  }
+}
+
 void APIConnection::on_serial_proxy_request(const SerialProxyRequest &msg) {
   auto &proxies = App.get_serial_proxies();
   if (msg.instance >= proxies.size()) {

esphome/components/api/api_connection.h

@@ -247,6 +247,7 @@ class APIConnection final : public APIServerConnectionBase {
   void on_serial_proxy_write_request(const SerialProxyWriteRequest &msg);
   void on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &msg);
   void on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg);
+  void on_serial_proxy_get_usb_info_request(const SerialProxyGetUsbInfoRequest &msg);
   void on_serial_proxy_request(const SerialProxyRequest &msg);
   void on_serial_proxy_set_mode_request(const SerialProxySetModeRequest &msg);
   void send_serial_proxy_data(const SerialProxyDataReceived &msg);

esphome/components/api/api_pb2.cpp

@@ -4278,6 +4278,44 @@ bool SerialProxySetModeRequest::decode_varint(uint32_t field_id, proto_varint_va
   }
   return true;
 }
+bool SerialProxyGetUsbInfoRequest::decode_varint(uint32_t field_id, proto_varint_value_t value) {
+  switch (field_id) {
+    case 1:
+      this->instance = value;
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+uint8_t *SerialProxyGetUsbInfoResponse::encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) const {
+  uint8_t *__restrict__ pos = buffer.get_pos();
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 1, this->instance);
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 2, static_cast<uint32_t>(this->status));
+  ProtoEncode::encode_bool(pos PROTO_ENCODE_DEBUG_ARG, 3, this->connected);
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 4, this->vendor_id);
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 5, this->product_id);
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 6, this->bcd_device);
+  ProtoEncode::encode_uint32(pos PROTO_ENCODE_DEBUG_ARG, 7, this->interface_number);
+  ProtoEncode::encode_string(pos PROTO_ENCODE_DEBUG_ARG, 8, this->manufacturer);
+  ProtoEncode::encode_string(pos PROTO_ENCODE_DEBUG_ARG, 9, this->product);
+  ProtoEncode::encode_string(pos PROTO_ENCODE_DEBUG_ARG, 10, this->serial_number);
+  return pos;
+}
+uint32_t SerialProxyGetUsbInfoResponse::calculate_size() const {
+  uint32_t size = 0;
+  size += ProtoSize::calc_uint32(1, this->instance);
+  size += this->status ? 2 : 0;
+  size += ProtoSize::calc_bool(1, this->connected);
+  size += ProtoSize::calc_uint32(1, this->vendor_id);
+  size += ProtoSize::calc_uint32(1, this->product_id);
+  size += ProtoSize::calc_uint32(1, this->bcd_device);
+  size += ProtoSize::calc_uint32(1, this->interface_number);
+  size += ProtoSize::calc_length(1, this->manufacturer.size());
+  size += ProtoSize::calc_length(1, this->product.size());
+  size += ProtoSize::calc_length(1, this->serial_number.size());
+  return size;
+}
 #endif
 #ifdef USE_BLUETOOTH_PROXY_CONNECTIONS
 bool BluetoothSetConnectionParamsRequest::decode_varint(uint32_t field_id, proto_varint_value_t value) {

esphome/components/api/api_pb2.h

@@ -23,6 +23,7 @@ enum SerialProxyPortType : uint32_t {
   SERIAL_PROXY_PORT_TYPE_TTL = 0,
   SERIAL_PROXY_PORT_TYPE_RS232 = 1,
   SERIAL_PROXY_PORT_TYPE_RS485 = 2,
+  SERIAL_PROXY_PORT_TYPE_USB_SERIAL = 3,
 };
 enum EntityCategory : uint32_t {
   ENTITY_CATEGORY_NONE = 0,
@@ -3435,6 +3436,46 @@ class SerialProxySetModeRequest final : public ProtoDecodableMessage {
  protected:
   bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
 };
+class SerialProxyGetUsbInfoRequest final : public ProtoDecodableMessage {
+ public:
+  static constexpr uint16_t MESSAGE_TYPE = 153;
+  static constexpr uint8_t ESTIMATED_SIZE = 4;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const LogString *message_name() const override { return LOG_STR("serial_proxy_get_usb_info_request"); }
+#endif
+  uint32_t instance{0};
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+  bool decode_varint(uint32_t field_id, proto_varint_value_t value) override;
+};
+class SerialProxyGetUsbInfoResponse final : public ProtoMessage {
+ public:
+  static constexpr uint16_t MESSAGE_TYPE = 154;
+  static constexpr uint8_t ESTIMATED_SIZE = 51;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const LogString *message_name() const override { return LOG_STR("serial_proxy_get_usb_info_response"); }
+#endif
+  uint32_t instance{0};
+  enums::SerialProxyStatus status{};
+  bool connected{false};
+  uint32_t vendor_id{0};
+  uint32_t product_id{0};
+  uint32_t bcd_device{0};
+  uint32_t interface_number{0};
+  StringRef manufacturer{};
+  StringRef product{};
+  StringRef serial_number{};
+  uint8_t *encode(ProtoWriteBuffer &buffer PROTO_ENCODE_DEBUG_PARAM) const;
+  uint32_t calculate_size() const;
+#ifdef HAS_PROTO_MESSAGE_DUMP
+  const char *dump_to(DumpBuffer &out) const override;
+#endif
+
+ protected:
+};
 #endif
 #ifdef USE_BLUETOOTH_PROXY_CONNECTIONS
 class BluetoothSetConnectionParamsRequest final : public ProtoDecodableMessage {
@@ -3477,7 +3518,7 @@ class BluetoothSetConnectionParamsResponse final : public ProtoMessage {
 #ifdef USE_ZIGBEE_PROXY
 class ZigbeeProxyRequest final : public ProtoDecodableMessage {
  public:
-  static constexpr uint16_t MESSAGE_TYPE = 153;
+  static constexpr uint16_t MESSAGE_TYPE = 155;
   static constexpr uint8_t ESTIMATED_SIZE = 21;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   const LogString *message_name() const override { return LOG_STR("zigbee_proxy_request"); }

esphome/components/api/api_pb2_dump.cpp

@@ -143,6 +143,8 @@ template<> const char *proto_enum_to_string<enums::SerialProxyPortType>(enums::S
       return ESPHOME_PSTR("SERIAL_PROXY_PORT_TYPE_RS232");
     case enums::SERIAL_PROXY_PORT_TYPE_RS485:
       return ESPHOME_PSTR("SERIAL_PROXY_PORT_TYPE_RS485");
+    case enums::SERIAL_PROXY_PORT_TYPE_USB_SERIAL:
+      return ESPHOME_PSTR("SERIAL_PROXY_PORT_TYPE_USB_SERIAL");
     default:
       return ESPHOME_PSTR("UNKNOWN");
   }
@@ -2839,6 +2841,25 @@ const char *SerialProxySetModeRequest::dump_to(DumpBuffer &out) const {
   dump_field(out, ESPHOME_PSTR("mode"), static_cast<enums::SerialProxyMode>(this->mode));
   return out.c_str();
 }
+const char *SerialProxyGetUsbInfoRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxyGetUsbInfoRequest"));
+  dump_field(out, ESPHOME_PSTR("instance"), this->instance);
+  return out.c_str();
+}
+const char *SerialProxyGetUsbInfoResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, ESPHOME_PSTR("SerialProxyGetUsbInfoResponse"));
+  dump_field(out, ESPHOME_PSTR("instance"), this->instance);
+  dump_field(out, ESPHOME_PSTR("status"), static_cast<enums::SerialProxyStatus>(this->status));
+  dump_field(out, ESPHOME_PSTR("connected"), this->connected);
+  dump_field(out, ESPHOME_PSTR("vendor_id"), this->vendor_id);
+  dump_field(out, ESPHOME_PSTR("product_id"), this->product_id);
+  dump_field(out, ESPHOME_PSTR("bcd_device"), this->bcd_device);
+  dump_field(out, ESPHOME_PSTR("interface_number"), this->interface_number);
+  dump_field(out, ESPHOME_PSTR("manufacturer"), this->manufacturer);
+  dump_field(out, ESPHOME_PSTR("product"), this->product);
+  dump_field(out, ESPHOME_PSTR("serial_number"), this->serial_number);
+  return out.c_str();
+}
 #endif
 #ifdef USE_BLUETOOTH_PROXY_CONNECTIONS
 const char *BluetoothSetConnectionParamsRequest::dump_to(DumpBuffer &out) const {

esphome/components/api/api_pb2_service.cpp

@@ -723,6 +723,17 @@ void APIConnection::read_message_(uint32_t msg_size, uint32_t msg_type, const ui
       break;
     }
 #endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyGetUsbInfoRequest::MESSAGE_TYPE: {
+      SerialProxyGetUsbInfoRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_get_usb_info_request"), msg);
+#endif
+      this->on_serial_proxy_get_usb_info_request(msg);
+      break;
+    }
+#endif
 #ifdef USE_ZIGBEE_PROXY
     case ZigbeeProxyRequest::MESSAGE_TYPE: {
       ZigbeeProxyRequest msg;

esphome/components/api/api_pb2_service.h

@@ -238,6 +238,10 @@ class APIServerConnectionBase {
 #ifdef USE_SERIAL_PROXY
   void on_serial_proxy_set_mode_request(const SerialProxySetModeRequest &value){};
 #endif
+#ifdef USE_SERIAL_PROXY
+  void on_serial_proxy_get_usb_info_request(const SerialProxyGetUsbInfoRequest &value){};
+#endif
+
 #ifdef USE_BLUETOOTH_PROXY_CONNECTIONS
   void on_bluetooth_set_connection_params_request(const BluetoothSetConnectionParamsRequest &value){};
 #endif

esphome/components/serial_proxy/__init__.py

@@ -18,9 +18,10 @@ from esphome import pins
 import esphome.codegen as cg
 from esphome.components import uart
 import esphome.config_validation as cv
-from esphome.const import CONF_ID, CONF_NAME
+from esphome.const import CONF_ID, CONF_NAME, CONF_UART_ID
 from esphome.core import CORE, coroutine_with_priority
 from esphome.coroutine import CoroPriority
+import esphome.final_validate as fv
 from esphome.types import ConfigType
 
 CODEOWNERS = ["@kbx81"]
@@ -34,11 +35,14 @@ SerialProxyTap = serial_proxy_ns.class_("SerialProxyTap")
 
 api_enums_ns = cg.esphome_ns.namespace("api").namespace("enums")
 SerialProxyPortType = api_enums_ns.enum("SerialProxyPortType")
+# User-selectable electrical types. USB_SERIAL is deliberately absent: it is derived
+# from the uart_id pointing at a usb_uart channel, never set by the user.
 SERIAL_PROXY_PORT_TYPES = {
     "TTL": SerialProxyPortType.SERIAL_PROXY_PORT_TYPE_TTL,
     "RS232": SerialProxyPortType.SERIAL_PROXY_PORT_TYPE_RS232,
     "RS485": SerialProxyPortType.SERIAL_PROXY_PORT_TYPE_RS485,
 }
+PORT_TYPE_USB_SERIAL = SerialProxyPortType.SERIAL_PROXY_PORT_TYPE_USB_SERIAL
 
 CONF_DTR_PIN = "dtr_pin"
 CONF_PORT_TYPE = "port_type"
@@ -63,7 +67,7 @@ CONFIG_SCHEMA = (
         {
             cv.GenerateID(): cv.declare_id(SerialProxy),
             cv.Required(CONF_NAME): cv.string_strict,
-            cv.Required(CONF_PORT_TYPE): cv.enum(SERIAL_PROXY_PORT_TYPES, upper=True),
+            cv.Optional(CONF_PORT_TYPE): cv.enum(SERIAL_PROXY_PORT_TYPES, upper=True),
             cv.Optional(CONF_RTS_PIN): pins.gpio_output_pin_schema,
             cv.Optional(CONF_DTR_PIN): pins.gpio_output_pin_schema,
         }
@@ -73,6 +77,26 @@ CONFIG_SCHEMA = (
 )
 
 
+def _uses_usb_uart(config: ConfigType, full_config: ConfigType) -> bool:
+    from esphome.components.usb_uart import is_usb_uart_channel
+
+    return is_usb_uart_channel(config[CONF_UART_ID], full_config)
+
+
+def _final_validate(config: ConfigType) -> ConfigType:
+    if _uses_usb_uart(config, fv.full_config.get()):
+        if CONF_PORT_TYPE in config:
+            raise cv.Invalid(
+                f"{CONF_PORT_TYPE} is set automatically for USB serial ports"
+            )
+    elif CONF_PORT_TYPE not in config:
+        raise cv.Invalid(f"{CONF_PORT_TYPE} is required")
+    return config
+
+
+FINAL_VALIDATE_SCHEMA = _final_validate
+
+
 @coroutine_with_priority(CoroPriority.FINAL)
 async def _add_serial_proxy_count_define() -> None:
     """Emit the SERIAL_PROXY_COUNT define once with the final instance count."""
@@ -87,7 +111,13 @@ async def to_code(config: ConfigType) -> None:
     await uart.register_uart_device(var, config)
     cg.add(cg.App.register_serial_proxy(var))
     cg.add(var.set_name(config[CONF_NAME]))
-    cg.add(var.set_port_type(config[CONF_PORT_TYPE]))
+    if _uses_usb_uart(config, CORE.config):
+        cg.add(var.set_port_type(PORT_TYPE_USB_SERIAL))
+        channel = await cg.get_variable(config[CONF_UART_ID])
+        cg.add(var.set_usb_channel(channel))
+        cg.add_define("USE_SERIAL_PROXY_USB_INFO")
+    else:
+        cg.add(var.set_port_type(config[CONF_PORT_TYPE]))
     cg.add_define("USE_SERIAL_PROXY")
 
     # Track instance count for the FINAL priority define

esphome/components/serial_proxy/serial_proxy.cpp

@@ -12,6 +12,10 @@
 #include "esphome/components/api/api_server.h"
 #endif
 
+#ifdef USE_SERIAL_PROXY_USB_INFO
+#include "esphome/components/usb_uart/usb_uart.h"
+#endif
+
 namespace esphome::serial_proxy {
 
 static const char *const TAG = "serial_proxy";
@@ -156,9 +160,10 @@ void SerialProxy::dump_config() {
                 "  RTS Pin: %s\n"
                 "  DTR Pin: %s",
                 this->instance_index_, this->name_ != nullptr ? this->name_ : "",
-                this->port_type_ == api::enums::SERIAL_PROXY_PORT_TYPE_RS485   ? LOG_STR_LITERAL("RS485")
-                : this->port_type_ == api::enums::SERIAL_PROXY_PORT_TYPE_RS232 ? LOG_STR_LITERAL("RS232")
-                                                                               : LOG_STR_LITERAL("TTL"),
+                this->port_type_ == api::enums::SERIAL_PROXY_PORT_TYPE_RS485        ? LOG_STR_LITERAL("RS485")
+                : this->port_type_ == api::enums::SERIAL_PROXY_PORT_TYPE_RS232      ? LOG_STR_LITERAL("RS232")
+                : this->port_type_ == api::enums::SERIAL_PROXY_PORT_TYPE_USB_SERIAL ? LOG_STR_LITERAL("USB_SERIAL")
+                                                                                    : LOG_STR_LITERAL("TTL"),
                 this->rts_pin_ != nullptr ? LOG_STR_LITERAL("configured") : LOG_STR_LITERAL("not configured"),
                 this->dtr_pin_ != nullptr ? LOG_STR_LITERAL("configured") : LOG_STR_LITERAL("not configured"));
 }
@@ -333,6 +338,27 @@ SerialProxyResult SerialProxy::set_modem_pins(api::APIConnection *api_connection
   return SerialProxyResult::SERIAL_PROXY_RESULT_OK;
 }
 
+#if defined(USE_SERIAL_PROXY_USB_INFO) && defined(USE_API)
+void SerialProxy::get_usb_info(usb_host::UsbDeviceInfo &info, api::SerialProxyGetUsbInfoResponse &resp) const {
+  if (this->usb_channel_ == nullptr) {
+    resp.status = api::enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED;
+    return;
+  }
+  resp.interface_number = this->usb_channel_->get_index();
+  if (!this->usb_channel_->get_parent()->get_device_info(info)) {
+    // No device attached right now; not an error
+    return;
+  }
+  resp.connected = true;
+  resp.vendor_id = info.vendor_id;
+  resp.product_id = info.product_id;
+  resp.bcd_device = info.bcd_device;
+  resp.manufacturer = StringRef(info.manufacturer);
+  resp.product = StringRef(info.product);
+  resp.serial_number = StringRef(info.serial_number);
+}
+#endif
+
 uint32_t SerialProxy::get_modem_pins() const {
   return (this->rts_state_ ? static_cast<uint32_t>(SERIAL_PROXY_LINE_STATE_FLAG_RTS) : 0u) |
          (this->dtr_state_ ? static_cast<uint32_t>(SERIAL_PROXY_LINE_STATE_FLAG_DTR) : 0u);

esphome/components/serial_proxy/serial_proxy.h

@@ -20,6 +20,15 @@
 #include "esphome/components/api/api_pb2.h"
 #endif
 
+#ifdef USE_SERIAL_PROXY_USB_INFO
+namespace esphome::usb_uart {
+class USBUartChannel;
+}  // namespace esphome::usb_uart
+namespace esphome::usb_host {
+struct UsbDeviceInfo;
+}  // namespace esphome::usb_host
+#endif
+
 // Forward-declare types needed outside the USE_API guard.
 namespace esphome::api {
 class APIConnection;
@@ -155,6 +164,17 @@ class SerialProxy final : public uart::UARTDevice, public Component {
   /// Set the DTR GPIO pin (from YAML configuration)
   void set_dtr_pin(GPIOPin *pin) { this->dtr_pin_ = pin; }
 
+#ifdef USE_SERIAL_PROXY_USB_INFO
+  /// Attach the USB UART channel behind this port (from code generation)
+  void set_usb_channel(usb_uart::USBUartChannel *channel) { this->usb_channel_ = channel; }
+
+#ifdef USE_API
+  /// Fill a USB info response for this port. The response's strings are views into
+  /// info, so info must outlive the send.
+  void get_usb_info(usb_host::UsbDeviceInfo &info, api::SerialProxyGetUsbInfoResponse &resp) const;
+#endif
+#endif
+
 #ifdef USE_SERIAL_PROXY_TAP
   /// Attach a traffic observer. At most one, set once at setup time.
   void set_tap(SerialProxyTap *tap) { this->tap_ = tap; }
@@ -251,6 +271,11 @@ class SerialProxy final : public uart::UARTDevice, public Component {
 #ifdef USE_SERIAL_PROXY_TAP
   SerialProxyTap *tap_{nullptr};
 #endif
+
+#ifdef USE_SERIAL_PROXY_USB_INFO
+  /// The USB UART channel behind this port; nullptr on non-USB ports
+  usb_uart::USBUartChannel *usb_channel_{nullptr};
+#endif
 };
 
 }  // namespace esphome::serial_proxy

esphome/components/usb_host/usb_host.h

@@ -117,6 +117,20 @@ struct UsbEvent {
 
 // callback function type.
 
+// USB string descriptors hold at most 126 characters; one more for the terminator
+static constexpr size_t DESC_STRING_BUF_SIZE = 128;
+
+/// Identity of a connected USB device, copied out of the descriptors the USB host
+/// stack caches for the lifetime of the connection
+struct UsbDeviceInfo {
+  uint16_t vendor_id;
+  uint16_t product_id;
+  uint16_t bcd_device;
+  char manufacturer[DESC_STRING_BUF_SIZE];
+  char product[DESC_STRING_BUF_SIZE];
+  char serial_number[DESC_STRING_BUF_SIZE];
+};
+
 enum ClientState {
   USB_CLIENT_INIT = 0,
   USB_CLIENT_OPEN,
@@ -144,6 +158,10 @@ class USBClient : public Component {
   bool control_transfer(uint8_t type, uint8_t request, uint16_t value, uint16_t index, const transfer_cb_t &callback,
                         const std::vector<uint8_t> &data = {});
 
+  /// Copy the connected device's identity out of the cached USB descriptors.
+  /// Returns false when no device is connected.
+  bool get_device_info(UsbDeviceInfo &info) const;
+
   // Lock-free event queue and pool for USB task to main loop communication
   // Must be public for access from static callbacks
   LockFreeQueue<UsbEvent, USB_EVENT_QUEUE_SIZE> event_queue;

esphome/components/usb_host/usb_host_client.cpp

@@ -143,10 +143,8 @@ static void usb_client_print_config_descriptor(const usb_config_desc_t *cfg_desc
   } while (next_desc != NULL);
 }
 #endif
-// USB string descriptors: bLength (uint8_t, max 255) includes the 2-byte header (bLength and bDescriptorType).
-// Character count = (bLength - 2) / 2, max 126 chars + null terminator.
-static constexpr size_t DESC_STRING_BUF_SIZE = 128;
-
+// bLength (uint8_t, max 255) includes the 2-byte header (bLength and bDescriptorType),
+// so character count = (bLength - 2) / 2.
 static const char *get_descriptor_string(const usb_str_desc_t *desc, std::span<char, DESC_STRING_BUF_SIZE> buffer) {
   if (desc == nullptr || desc->bLength < 2)
     return "(unspecified)";
@@ -162,6 +160,41 @@ static const char *get_descriptor_string(const usb_str_desc_t *desc, std::span<c
   return buffer.data();
 }
 
+// A missing descriptor copies as an empty string, unlike the "(unspecified)"
+// placeholder the logging helper above uses
+static void copy_descriptor_string(const usb_str_desc_t *desc, std::span<char, DESC_STRING_BUF_SIZE> buffer) {
+  buffer[0] = '\0';
+  if (desc == nullptr || desc->bLength < 2)
+    return;
+  int char_count = (desc->bLength - 2) / 2;
+  char *p = buffer.data();
+  char *end = p + buffer.size() - 1;
+  for (int i = 0; i != char_count && p < end; i++) {
+    auto c = desc->wData[i];
+    if (c < 0x100)
+      *p++ = static_cast<char>(c);
+  }
+  *p = '\0';
+}
+
+bool USBClient::get_device_info(UsbDeviceInfo &info) const {
+  if (this->state_ != USB_CLIENT_CONNECTED)
+    return false;
+  const usb_device_desc_t *desc;
+  if (usb_host_get_device_descriptor(this->device_handle_, &desc) != ESP_OK)
+    return false;
+  info.vendor_id = desc->idVendor;
+  info.product_id = desc->idProduct;
+  info.bcd_device = desc->bcdDevice;
+  usb_device_info_t dev_info;
+  if (usb_host_device_info(this->device_handle_, &dev_info) != ESP_OK)
+    return false;
+  copy_descriptor_string(dev_info.str_desc_manufacturer, info.manufacturer);
+  copy_descriptor_string(dev_info.str_desc_product, info.product);
+  copy_descriptor_string(dev_info.str_desc_serial_num, info.serial_number);
+  return true;
+}
+
 // CALLBACK CONTEXT: USB task (called from usb_host_client_handle_events in USB task)
 static void client_event_cb(const usb_host_client_event_msg_t *event_msg, void *ptr) {
   auto *client = static_cast<USBClient *>(ptr);

esphome/components/usb_uart/__init__.py

@@ -16,7 +16,7 @@ from esphome.const import (
     CONF_DUMMY_RECEIVER,
     CONF_ID,
 )
-from esphome.core import CORE
+from esphome.core import CORE, ID
 from esphome.cpp_types import Component
 from esphome.types import ConfigType
 
@@ -27,6 +27,16 @@ usb_uart_ns = cg.esphome_ns.namespace("usb_uart")
 USBUartComponent = usb_uart_ns.class_("USBUartComponent", Component)
 USBUartChannel = usb_uart_ns.class_("USBUartChannel", UARTComponent)
 
+
+def is_usb_uart_channel(uart_id: ID, full_config: ConfigType) -> bool:
+    """Return True if the given ID refers to a channel of a configured usb_uart device."""
+    return any(
+        channel[CONF_ID] == uart_id
+        for device in full_config.get("usb_uart") or []
+        for channel in device[CONF_CHANNELS]
+    )
+
+
 UARTParityOptions = usb_uart_ns.enum("UARTParityOptions")
 UART_PARITY_OPTIONS = {
     "NONE": UARTParityOptions.UART_CONFIG_PARITY_NONE,

esphome/components/usb_uart/usb_uart.h

@@ -164,6 +164,9 @@ class USBUartChannelBase : public uart::UARTComponent, public Parented<USBUartCo
   /// they arrive, eliminating one full main-loop-wakeup cycle of latency.
   void set_rx_callback(std::function<void()> cb) { this->rx_callback_ = std::move(cb); }
 
+  /// Channel index on the bridge (interface number on multi-port bridges)
+  uint8_t get_index() const { return this->index_; }
+
  protected:
   // Not directly instantiable; construct a concrete channel type instead.
   USBUartChannelBase(uint8_t index, uint16_t buffer_size) : input_buffer_(RingBuffer(buffer_size)), index_(index) {}

esphome/core/defines.h

@@ -395,6 +395,10 @@
 #define USB_HOST_MAX_REQUESTS 16
 #define USB_HOST_MAX_PACKET_SIZE 64
 #define USB_UART_OUTPUT_CHUNK_COUNT 5
+// USB identity on serial proxy ports needs the usb_host stack
+#ifdef USE_ESP32
+#define USE_SERIAL_PROXY_USB_INFO
+#endif
 
 #ifdef USE_ARDUINO
 #define USE_ARDUINO_VERSION_CODE VERSION_CODE(3, 3, 7)

tests/components/serial_proxy/test-usb.esp32-s3-idf.yaml

@@ -0,0 +1,21 @@
+wifi:
+  ssid: MySSID
+  password: password1
+
+api:
+
+usb_host:
+
+# port_type is omitted deliberately: a port on a USB UART channel derives USB_SERIAL
+usb_uart:
+  - type: CDC_ACM
+    vid: 0x303A
+    pid: 0x831A
+    channels:
+      - id: usb_serial_channel
+        baud_rate: 460800
+
+serial_proxy:
+  - id: serial_proxy_usb
+    uart_id: usb_serial_channel
+    name: USB Serial Port

tests/components/zigbee_proxy/test-usb.esp32-s3-idf.yaml

@@ -21,7 +21,6 @@ serial_proxy:
   - id: zigbee_usb_serial
     uart_id: zigbee_usb_channel
     name: Zigbee
-    port_type: TTL
 
 zigbee_proxy:
   serial_proxy_id: zigbee_usb_serial