diff --git a/homeassistant/components/directv/config_flow.py b/homeassistant/components/directv/config_flow.py
index d1b3a6cbe62..b7d1604622e 100644
--- a/homeassistant/components/directv/config_flow.py
+++ b/homeassistant/components/directv/config_flow.py
@@ -12,6 +12,7 @@ from homeassistant.config_entries import CONN_CLASS_LOCAL_POLL, ConfigFlow
 from homeassistant.const import CONF_HOST, CONF_NAME
 from homeassistant.core import callback
 from homeassistant.exceptions import HomeAssistantError
+from homeassistant.helpers.typing import DiscoveryInfoType
 
 from .const import DEFAULT_PORT
 from .const import DOMAIN  # pylint: disable=unused-import
@@ -83,7 +84,7 @@ class DirecTVConfigFlow(ConfigFlow, domain=DOMAIN):
         return self.async_create_entry(title=info["title"], data=user_input)
 
     async def async_step_ssdp(
-        self, discovery_info: Optional[Dict] = None
+        self, discovery_info: Optional[DiscoveryInfoType] = None
     ) -> Dict[str, Any]:
         """Handle a flow initialized by discovery."""
         host = urlparse(discovery_info[ATTR_SSDP_LOCATION]).hostname
diff --git a/homeassistant/components/gtfs/sensor.py b/homeassistant/components/gtfs/sensor.py
index 2bd0ce1b09f..08550ed80b8 100644
--- a/homeassistant/components/gtfs/sensor.py
+++ b/homeassistant/components/gtfs/sensor.py
@@ -19,7 +19,11 @@ from homeassistant.const import (
 )
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity import Entity
-from homeassistant.helpers.typing import ConfigType, HomeAssistantType
+from homeassistant.helpers.typing import (
+    ConfigType,
+    DiscoveryInfoType,
+    HomeAssistantType,
+)
 from homeassistant.util import slugify
 import homeassistant.util.dt as dt_util
 
@@ -332,7 +336,7 @@ def setup_platform(
     hass: HomeAssistantType,
     config: ConfigType,
     add_entities: Callable[[list], None],
-    discovery_info: Optional[dict] = None,
+    discovery_info: Optional[DiscoveryInfoType] = None,
 ) -> None:
     """Set up the GTFS sensor."""
     gtfs_dir = hass.config.path(DEFAULT_PATH)
diff --git a/homeassistant/components/here_travel_time/sensor.py b/homeassistant/components/here_travel_time/sensor.py
index d93cfdf7053..c88aeb8e5a0 100644
--- a/homeassistant/components/here_travel_time/sensor.py
+++ b/homeassistant/components/here_travel_time/sensor.py
@@ -24,6 +24,7 @@ from homeassistant.core import HomeAssistant, State, callback
 from homeassistant.helpers import location
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity import Entity
+from homeassistant.helpers.typing import DiscoveryInfoType
 import homeassistant.util.dt as dt
 
 _LOGGER = logging.getLogger(__name__)
@@ -144,7 +145,7 @@ async def async_setup_platform(
     hass: HomeAssistant,
     config: Dict[str, Union[str, bool]],
     async_add_entities: Callable,
-    discovery_info: None = None,
+    discovery_info: Optional[DiscoveryInfoType] = None,
 ) -> None:
     """Set up the HERE travel time platform."""
 
diff --git a/homeassistant/components/remote/__init__.py b/homeassistant/components/remote/__init__.py
index 3a71ebb94d1..0a598ae345d 100644
--- a/homeassistant/components/remote/__init__.py
+++ b/homeassistant/components/remote/__init__.py
@@ -114,9 +114,7 @@ async def async_setup(hass: HomeAssistantType, config: ConfigType) -> bool:
 
 async def async_setup_entry(hass: HomeAssistantType, entry: ConfigEntry) -> bool:
     """Set up a config entry."""
-    return cast(
-        bool, await cast(EntityComponent, hass.data[DOMAIN]).async_setup_entry(entry)
-    )
+    return await cast(EntityComponent, hass.data[DOMAIN]).async_setup_entry(entry)
 
 
 async def async_unload_entry(hass: HomeAssistantType, entry: ConfigEntry) -> bool:
diff --git a/homeassistant/components/switch/light.py b/homeassistant/components/switch/light.py
index 5486b8d880c..92b64b36b93 100644
--- a/homeassistant/components/switch/light.py
+++ b/homeassistant/components/switch/light.py
@@ -1,6 +1,6 @@
 """Light support for switch entities."""
 import logging
-from typing import Callable, Dict, Optional, Sequence, cast
+from typing import Callable, Optional, Sequence, cast
 
 import voluptuous as vol
 
@@ -17,7 +17,11 @@ from homeassistant.core import CALLBACK_TYPE, State, callback
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.entity import Entity
 from homeassistant.helpers.event import async_track_state_change
-from homeassistant.helpers.typing import ConfigType, HomeAssistantType
+from homeassistant.helpers.typing import (
+    ConfigType,
+    DiscoveryInfoType,
+    HomeAssistantType,
+)
 
 # mypy: allow-untyped-calls, allow-untyped-defs, no-check-untyped-defs
 
@@ -37,7 +41,7 @@ async def async_setup_platform(
     hass: HomeAssistantType,
     config: ConfigType,
     async_add_entities: Callable[[Sequence[Entity], bool], None],
-    discovery_info: Optional[Dict] = None,
+    discovery_info: Optional[DiscoveryInfoType] = None,
 ) -> None:
     """Initialize Light Switch platform."""
     async_add_entities(
diff --git a/homeassistant/components/switcher_kis/__init__.py b/homeassistant/components/switcher_kis/__init__.py
index 63f2aa47a3a..0545687b003 100644
--- a/homeassistant/components/switcher_kis/__init__.py
+++ b/homeassistant/components/switcher_kis/__init__.py
@@ -20,6 +20,7 @@ from homeassistant.helpers.dispatcher import async_dispatcher_send
 from homeassistant.helpers.event import async_track_time_interval
 from homeassistant.helpers.typing import (
     ContextType,
+    DiscoveryInfoType,
     EventType,
     HomeAssistantType,
     ServiceCallType,
@@ -115,7 +116,7 @@ async def async_setup(hass: HomeAssistantType, config: Dict) -> bool:
     hass.data[DOMAIN] = {DATA_DEVICE: device_data}
 
     async def async_switch_platform_discovered(
-        platform: str, discovery_info: Optional[Dict]
+        platform: str, discovery_info: DiscoveryInfoType
     ) -> None:
         """Use for registering services after switch platform is discovered."""
         if platform != DOMAIN:
diff --git a/homeassistant/components/vizio/config_flow.py b/homeassistant/components/vizio/config_flow.py
index 7dc4b19fa83..ba3ac5107bb 100644
--- a/homeassistant/components/vizio/config_flow.py
+++ b/homeassistant/components/vizio/config_flow.py
@@ -1,7 +1,7 @@
 """Config flow for Vizio."""
 import copy
 import logging
-from typing import Any, Dict
+from typing import Any, Dict, Optional
 
 from pyvizio import VizioAsync, async_guess_device_type
 import voluptuous as vol
@@ -23,6 +23,7 @@ from homeassistant.const import (
 from homeassistant.core import callback
 from homeassistant.helpers import config_validation as cv
 from homeassistant.helpers.aiohttp_client import async_get_clientsession
+from homeassistant.helpers.typing import DiscoveryInfoType
 
 from .const import (
     CONF_APPS,
@@ -318,7 +319,7 @@ class VizioConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
         return await self.async_step_user(user_input=import_config)
 
     async def async_step_zeroconf(
-        self, discovery_info: Dict[str, Any] = None
+        self, discovery_info: Optional[DiscoveryInfoType] = None
     ) -> Dict[str, Any]:
         """Handle zeroconf discovery."""
 
diff --git a/homeassistant/components/zone/__init__.py b/homeassistant/components/zone/__init__.py
index c71026ea79c..08304df8137 100644
--- a/homeassistant/components/zone/__init__.py
+++ b/homeassistant/components/zone/__init__.py
@@ -221,7 +221,7 @@ async def async_setup(hass: HomeAssistant, config: Dict) -> bool:
 
     home_zone = Zone(_home_conf(hass), True,)
     home_zone.entity_id = ENTITY_ID_HOME
-    await component.async_add_entities([home_zone])  # type: ignore
+    await component.async_add_entities([home_zone])
 
     async def core_config_updated(_: Event) -> None:
         """Handle core config updated."""
diff --git a/homeassistant/helpers/collection.py b/homeassistant/helpers/collection.py
index 8234dd6ec87..e720887eb70 100644
--- a/homeassistant/helpers/collection.py
+++ b/homeassistant/helpers/collection.py
@@ -266,7 +266,7 @@ def attach_entity_component_collection(
         """Handle a collection change."""
         if change_type == CHANGE_ADDED:
             entity = create_entity(config)
-            await entity_component.async_add_entities([entity])  # type: ignore
+            await entity_component.async_add_entities([entity])
             entities[item_id] = entity
             return
 
diff --git a/homeassistant/helpers/discovery.py b/homeassistant/helpers/discovery.py
index 806540e57ce..ea20d8c9216 100644
--- a/homeassistant/helpers/discovery.py
+++ b/homeassistant/helpers/discovery.py
@@ -5,7 +5,7 @@ There are two different types of discoveries that can be fired/listened for.
  - listen_platform/discover_platform is for platforms. These are used by
    components to allow discovery of their platforms.
 """
-from typing import Callable, Collection, Union
+from typing import Any, Callable, Collection, Dict, Optional, Union
 
 from homeassistant import core, setup
 from homeassistant.const import ATTR_DISCOVERED, ATTR_SERVICE, EVENT_PLATFORM_DISCOVERED
@@ -90,7 +90,9 @@ def listen_platform(
 
 @bind_hass
 def async_listen_platform(
-    hass: core.HomeAssistant, component: str, callback: Callable
+    hass: core.HomeAssistant,
+    component: str,
+    callback: Callable[[str, Optional[Dict[str, Any]]], Any],
 ) -> None:
     """Register a platform loader listener.
 
diff --git a/homeassistant/helpers/entity_component.py b/homeassistant/helpers/entity_component.py
index f6c473dd418..71c57dc13f1 100644
--- a/homeassistant/helpers/entity_component.py
+++ b/homeassistant/helpers/entity_component.py
@@ -4,12 +4,14 @@ from datetime import timedelta
 from itertools import chain
 import logging
 from types import ModuleType
-from typing import Dict, Optional, cast
+from typing import Any, Callable, Dict, Iterable, List, Optional, Tuple, Union
+
+import voluptuous as vol
 
 from homeassistant import config as conf_util
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import CONF_ENTITY_NAMESPACE, CONF_SCAN_INTERVAL
-from homeassistant.core import HomeAssistant, callback
+from homeassistant.core import HomeAssistant, ServiceCall, callback
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.helpers import (
     config_per_platform,
@@ -18,13 +20,12 @@ from homeassistant.helpers import (
     entity,
     service,
 )
+from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
 from homeassistant.loader import async_get_integration, bind_hass
 from homeassistant.setup import async_prepare_setup_platform
 
 from .entity_platform import EntityPlatform
 
-# mypy: allow-untyped-defs, no-check-untyped-defs
-
 DEFAULT_SCAN_INTERVAL = timedelta(seconds=15)
 DATA_INSTANCES = "entity_components"
 
@@ -75,18 +76,18 @@ class EntityComponent:
         self.domain = domain
         self.scan_interval = scan_interval
 
-        self.config = None
+        self.config: Optional[ConfigType] = None
 
-        self._platforms: Dict[str, EntityPlatform] = {
-            domain: self._async_init_entity_platform(domain, None)
-        }
+        self._platforms: Dict[
+            Union[str, Tuple[str, Optional[timedelta], Optional[str]]], EntityPlatform
+        ] = {domain: self._async_init_entity_platform(domain, None)}
         self.async_add_entities = self._platforms[domain].async_add_entities
         self.add_entities = self._platforms[domain].add_entities
 
         hass.data.setdefault(DATA_INSTANCES, {})[domain] = self
 
     @property
-    def entities(self):
+    def entities(self) -> Iterable[entity.Entity]:
         """Return an iterable that returns all entities."""
         return chain.from_iterable(
             platform.entities.values() for platform in self._platforms.values()
@@ -95,19 +96,23 @@ class EntityComponent:
     def get_entity(self, entity_id: str) -> Optional[entity.Entity]:
         """Get an entity."""
         for platform in self._platforms.values():
-            entity_obj = cast(Optional[entity.Entity], platform.entities.get(entity_id))
+            entity_obj = platform.entities.get(entity_id)
             if entity_obj is not None:
                 return entity_obj
         return None
 
-    def setup(self, config):
+    def setup(self, config: ConfigType) -> None:
         """Set up a full entity component.
 
         This doesn't block the executor to protect from deadlocks.
         """
-        self.hass.add_job(self.async_setup(config))
+        self.hass.add_job(
+            self.async_setup(  # type: ignore
+                config
+            )
+        )
 
-    async def async_setup(self, config):
+    async def async_setup(self, config: ConfigType) -> None:
         """Set up a full entity component.
 
         Loads the platforms from the config and will listen for supported
@@ -127,7 +132,9 @@ class EntityComponent:
 
         # Generic discovery listener for loading platform dynamically
         # Refer to: homeassistant.components.discovery.load_platform()
-        async def component_platform_discovered(platform, info):
+        async def component_platform_discovered(
+            platform: str, info: Optional[Dict[str, Any]]
+        ) -> None:
             """Handle the loading of a platform."""
             await self.async_setup_platform(platform, {}, info)
 
@@ -135,7 +142,7 @@ class EntityComponent:
             self.hass, self.domain, component_platform_discovered
         )
 
-    async def async_setup_entry(self, config_entry):
+    async def async_setup_entry(self, config_entry: ConfigEntry) -> bool:
         """Set up a config entry."""
         platform_type = config_entry.domain
         platform = await async_prepare_setup_platform(
@@ -161,7 +168,7 @@ class EntityComponent:
             scan_interval=getattr(platform, "SCAN_INTERVAL", None),
         )
 
-        return await self._platforms[key].async_setup_entry(config_entry)
+        return await self._platforms[key].async_setup_entry(config_entry)  # type: ignore
 
     async def async_unload_entry(self, config_entry: ConfigEntry) -> bool:
         """Unload a config entry."""
@@ -175,24 +182,32 @@ class EntityComponent:
         await platform.async_reset()
         return True
 
-    async def async_extract_from_service(self, service_call, expand_group=True):
+    async def async_extract_from_service(
+        self, service_call: ServiceCall, expand_group: bool = True
+    ) -> List[entity.Entity]:
         """Extract all known and available entities from a service call.
 
         Will return an empty list if entities specified but unknown.
 
         This method must be run in the event loop.
         """
-        return await service.async_extract_entities(
+        return await service.async_extract_entities(  # type: ignore
             self.hass, self.entities, service_call, expand_group
         )
 
     @callback
-    def async_register_entity_service(self, name, schema, func, required_features=None):
+    def async_register_entity_service(
+        self,
+        name: str,
+        schema: Union[Dict[str, Any], vol.Schema],
+        func: str,
+        required_features: Optional[int] = None,
+    ) -> None:
         """Register an entity service."""
         if isinstance(schema, dict):
             schema = cv.make_entity_service_schema(schema)
 
-        async def handle_service(call):
+        async def handle_service(call: Callable) -> None:
             """Handle the service."""
             await self.hass.helpers.service.entity_service_call(
                 self._platforms.values(), func, call, required_features
@@ -201,8 +216,11 @@ class EntityComponent:
         self.hass.services.async_register(self.domain, name, handle_service, schema)
 
     async def async_setup_platform(
-        self, platform_type, platform_config, discovery_info=None
-    ):
+        self,
+        platform_type: str,
+        platform_config: ConfigType,
+        discovery_info: Optional[DiscoveryInfoType] = None,
+    ) -> None:
         """Set up a platform for this component."""
         if self.config is None:
             raise RuntimeError("async_setup needs to be called first")
@@ -227,7 +245,9 @@ class EntityComponent:
                 platform_type, platform, scan_interval, entity_namespace
             )
 
-        await self._platforms[key].async_setup(platform_config, discovery_info)
+        await self._platforms[key].async_setup(  # type: ignore
+            platform_config, discovery_info
+        )
 
     async def _async_reset(self) -> None:
         """Remove entities and reset the entity component to initial values.
@@ -285,7 +305,7 @@ class EntityComponent:
         if scan_interval is None:
             scan_interval = self.scan_interval
 
-        return EntityPlatform(  # type: ignore
+        return EntityPlatform(
             hass=self.hass,
             logger=self.logger,
             domain=self.domain,
diff --git a/homeassistant/helpers/entity_platform.py b/homeassistant/helpers/entity_platform.py
index e1e046eaa6d..0c288b0ad21 100644
--- a/homeassistant/helpers/entity_platform.py
+++ b/homeassistant/helpers/entity_platform.py
@@ -1,18 +1,24 @@
 """Class to manage the entities for a single platform."""
 import asyncio
 from contextvars import ContextVar
-from datetime import datetime
-from typing import Optional
+from datetime import datetime, timedelta
+from logging import Logger
+from types import ModuleType
+from typing import TYPE_CHECKING, Dict, Iterable, List, Optional, cast
 
 from homeassistant.const import DEVICE_DEFAULT_NAME
-from homeassistant.core import callback, split_entity_id, valid_entity_id
+from homeassistant.core import CALLBACK_TYPE, callback, split_entity_id, valid_entity_id
 from homeassistant.exceptions import HomeAssistantError, PlatformNotReady
 from homeassistant.helpers import config_validation as cv, service
+from homeassistant.helpers.typing import HomeAssistantType
 from homeassistant.util.async_ import run_callback_threadsafe
 
 from .entity_registry import DISABLED_INTEGRATION
 from .event import async_call_later, async_track_time_interval
 
+if TYPE_CHECKING:
+    from .entity import Entity
+
 # mypy: allow-untyped-defs, no-check-untyped-defs
 
 SLOW_SETUP_WARNING = 10
@@ -26,23 +32,15 @@ class EntityPlatform:
     def __init__(
         self,
         *,
-        hass,
-        logger,
-        domain,
-        platform_name,
-        platform,
-        scan_interval,
-        entity_namespace,
+        hass: HomeAssistantType,
+        logger: Logger,
+        domain: str,
+        platform_name: str,
+        platform: Optional[ModuleType],
+        scan_interval: timedelta,
+        entity_namespace: Optional[str],
     ):
-        """Initialize the entity platform.
-
-        hass: HomeAssistant
-        logger: Logger
-        domain: str
-        platform_name: str
-        scan_interval: timedelta
-        entity_namespace: str
-        """
+        """Initialize the entity platform."""
         self.hass = hass
         self.logger = logger
         self.domain = domain
@@ -51,13 +49,13 @@ class EntityPlatform:
         self.scan_interval = scan_interval
         self.entity_namespace = entity_namespace
         self.config_entry = None
-        self.entities = {}
-        self._tasks = []
+        self.entities: Dict[str, Entity] = {}  # pylint: disable=used-before-assignment
+        self._tasks: List[asyncio.Future] = []
         # Method to cancel the state change listener
-        self._async_unsub_polling = None
+        self._async_unsub_polling: Optional[CALLBACK_TYPE] = None
         # Method to cancel the retry of setup
-        self._async_cancel_retry_setup = None
-        self._process_updates = None
+        self._async_cancel_retry_setup: Optional[CALLBACK_TYPE] = None
+        self._process_updates: Optional[asyncio.Lock] = None
 
         # Platform is None for the EntityComponent "catch-all" EntityPlatform
         # which powers entity_component.add_entities
@@ -224,7 +222,9 @@ class EntityPlatform:
         finally:
             warn_task.cancel()
 
-    def _schedule_add_entities(self, new_entities, update_before_add=False):
+    def _schedule_add_entities(
+        self, new_entities: Iterable["Entity"], update_before_add: bool = False
+    ) -> None:
         """Schedule adding entities for a single platform, synchronously."""
         run_callback_threadsafe(
             self.hass.loop,
@@ -234,17 +234,24 @@ class EntityPlatform:
         ).result()
 
     @callback
-    def _async_schedule_add_entities(self, new_entities, update_before_add=False):
+    def _async_schedule_add_entities(
+        self, new_entities: Iterable["Entity"], update_before_add: bool = False
+    ) -> None:
         """Schedule adding entities for a single platform async."""
         self._tasks.append(
-            self.hass.async_add_job(
-                self.async_add_entities(
-                    new_entities, update_before_add=update_before_add
-                )
+            cast(
+                asyncio.Future,
+                self.hass.async_add_job(
+                    self.async_add_entities(  # type: ignore
+                        new_entities, update_before_add=update_before_add
+                    ),
+                ),
             )
         )
 
-    def add_entities(self, new_entities, update_before_add=False):
+    def add_entities(
+        self, new_entities: Iterable["Entity"], update_before_add: bool = False
+    ) -> None:
         """Add entities for a single platform."""
         # That avoid deadlocks
         if update_before_add:
@@ -258,7 +265,9 @@ class EntityPlatform:
             self.hass.loop,
         ).result()
 
-    async def async_add_entities(self, new_entities, update_before_add=False):
+    async def async_add_entities(
+        self, new_entities: Iterable["Entity"], update_before_add: bool = False
+    ) -> None:
         """Add entities for a single platform async.
 
         This method must be run in the event loop.
@@ -272,7 +281,7 @@ class EntityPlatform:
         device_registry = await hass.helpers.device_registry.async_get_registry()
         entity_registry = await hass.helpers.entity_registry.async_get_registry()
         tasks = [
-            self._async_add_entity(
+            self._async_add_entity(  # type: ignore
                 entity, update_before_add, entity_registry, device_registry
             )
             for entity in new_entities
@@ -290,7 +299,9 @@ class EntityPlatform:
             return
 
         self._async_unsub_polling = async_track_time_interval(
-            self.hass, self._update_entity_states, self.scan_interval
+            self.hass,
+            self._update_entity_states,  # type: ignore
+            self.scan_interval,
         )
 
     async def _async_add_entity(
@@ -515,7 +526,7 @@ class EntityPlatform:
             for entity in self.entities.values():
                 if not entity.should_poll:
                     continue
-                tasks.append(entity.async_update_ha_state(True))
+                tasks.append(entity.async_update_ha_state(True))  # type: ignore
 
             if tasks:
                 await asyncio.wait(tasks)
diff --git a/homeassistant/helpers/typing.py b/homeassistant/helpers/typing.py
index 6e31301066c..c7859d9d1d9 100644
--- a/homeassistant/helpers/typing.py
+++ b/homeassistant/helpers/typing.py
@@ -8,6 +8,7 @@ import homeassistant.core
 GPSType = Tuple[float, float]
 ConfigType = Dict[str, Any]
 ContextType = homeassistant.core.Context
+DiscoveryInfoType = Dict[str, Any]
 EventType = homeassistant.core.Event
 HomeAssistantType = homeassistant.core.HomeAssistant
 ServiceCallType = homeassistant.core.ServiceCall