Support USB discovery (#3100)

* Support USB discovery

* fix policy

* Fix scan command

* address comments

Co-authored-by: Ludeeus <ludeeus@ludeeus.dev>

supervisor/homeassistant/module.py

@@ -18,13 +18,17 @@ from ..const import (
     ATTR_PORT,
     ATTR_REFRESH_TOKEN,
     ATTR_SSL,
+    ATTR_TYPE,
     ATTR_UUID,
     ATTR_VERSION,
     ATTR_WAIT_BOOT,
     ATTR_WATCHDOG,
     FILE_HASSIO_HOMEASSISTANT,
+    BusEvent,
 )
 from ..coresys import CoreSys, CoreSysAttributes
+from ..hardware.const import PolicyGroup
+from ..hardware.data import Device
 from ..utils.common import FileConfiguration
 from .api import HomeAssistantAPI
 from .core import HomeAssistantCore
@@ -238,6 +242,9 @@ class HomeAssistant(FileConfiguration, CoreSysAttributes):
         """Prepare Home Assistant object."""
         await asyncio.wait([self.secrets.load(), self.core.load()])
 
+        # Register for events
+        self.sys_bus.register_event(BusEvent.HARDWARE_NEW_DEVICE, self._hardware_events)
+
     def write_pulse(self):
         """Write asound config to file and return True on success."""
         pulse_config = self.sys_plugins.audio.pulse_client(
@@ -256,3 +263,20 @@ class HomeAssistant(FileConfiguration, CoreSysAttributes):
             _LOGGER.error("Home Assistant can't write pulse/client.config: %s", err)
         else:
             _LOGGER.info("Update pulse/client.config: %s", self.path_pulse)
+
+    async def _hardware_events(self, device: Device) -> None:
+        """Process hardware requests."""
+        if (
+            not self.sys_hardware.policy.is_match_cgroup(PolicyGroup.UART, device)
+            or not self.version
+            or self.version < "2021.9.0"
+        ):
+            return
+
+        configuration = await self.sys_homeassistant.websocket.async_send_command(
+            {ATTR_TYPE: "get_config"}
+        )
+        if not configuration or "usb" not in configuration.get("components", []):
+            return
+
+        self.sys_homeassistant.websocket.send_command({ATTR_TYPE: "usb/scan"})