Add base class for all modbus platforms (#50878)

* Add base for all platforms.

* Please pylint.

homeassistant/components/modbus/base_platform.py

@@ -0,0 +1,67 @@
+"""Base implementation for all modbus platforms."""
+from __future__ import annotations
+
+from abc import abstractmethod
+from datetime import timedelta
+import logging
+from typing import Any
+
+from homeassistant.const import (
+    CONF_ADDRESS,
+    CONF_DEVICE_CLASS,
+    CONF_NAME,
+    CONF_SCAN_INTERVAL,
+    CONF_SLAVE,
+)
+from homeassistant.helpers.entity import Entity
+from homeassistant.helpers.event import async_track_time_interval
+
+from .const import CONF_INPUT_TYPE
+from .modbus import ModbusHub
+
+PARALLEL_UPDATES = 1
+_LOGGER = logging.getLogger(__name__)
+
+
+class BasePlatform(Entity):
+    """Base for readonly platforms."""
+
+    def __init__(self, hub: ModbusHub, entry: dict[str, Any]) -> None:
+        """Initialize the Modbus binary sensor."""
+        self._hub = hub
+        self._name = entry[CONF_NAME]
+        self._slave = entry.get(CONF_SLAVE)
+        self._address = int(entry[CONF_ADDRESS])
+        self._device_class = entry.get(CONF_DEVICE_CLASS)
+        self._input_type = entry[CONF_INPUT_TYPE]
+        self._value = None
+        self._available = True
+        self._scan_interval = timedelta(seconds=entry[CONF_SCAN_INTERVAL])
+
+    @abstractmethod
+    async def async_update(self, now=None):
+        """Virtual function to be overwritten."""
+
+    async def async_base_added_to_hass(self):
+        """Handle entity which will be added."""
+        async_track_time_interval(self.hass, self.async_update, self._scan_interval)
+
+    @property
+    def name(self):
+        """Return the name of the sensor."""
+        return self._name
+
+    @property
+    def should_poll(self):
+        """Return True if entity has to be polled for state."""
+        return False
+
+    @property
+    def device_class(self) -> str | None:
+        """Return the device class of the sensor."""
+        return self._device_class
+
+    @property
+    def available(self) -> bool:
+        """Return True if entity is available."""
+        return self._available