Add iot brightness feature (#808)

kasa/iot/iotbulb.py

@@ -12,6 +12,7 @@ except ImportError:
 from ..bulb import HSV, Bulb, BulbPreset, ColorTempRange
 from ..device_type import DeviceType
 from ..deviceconfig import DeviceConfig
+from ..feature import Feature, FeatureType
 from ..protocol import BaseProtocol
 from .iotdevice import IotDevice, KasaException, requires_update
 from .modules import Antitheft, Cloud, Countdown, Emeter, Schedule, Time, Usage
@@ -204,6 +205,22 @@ class IotBulb(IotDevice, Bulb):
         self.add_module("countdown", Countdown(self, "countdown"))
         self.add_module("cloud", Cloud(self, "smartlife.iot.common.cloud"))
 
+    async def _initialize_features(self):
+        await super()._initialize_features()
+
+        if bool(self.sys_info["is_dimmable"]):  # pragma: no branch
+            self._add_feature(
+                Feature(
+                    device=self,
+                    name="Brightness",
+                    attribute_getter="brightness",
+                    attribute_setter="set_brightness",
+                    minimum_value=1,
+                    maximum_value=100,
+                    type=FeatureType.Number,
+                )
+            )
+
     @property  # type: ignore
     @requires_update
     def is_color(self) -> bool: