Add restore_mode to rotary_encoder (#2643)

esphome/components/rotary_encoder/rotary_encoder.h

@@ -10,6 +10,12 @@
 namespace esphome {
 namespace rotary_encoder {
 
+/// All possible restore modes for the rotary encoder
+enum RotaryEncoderRestoreMode {
+  ROTARY_ENCODER_RESTORE_DEFAULT_ZERO,  /// try to restore counter, otherwise set to zero
+  ROTARY_ENCODER_ALWAYS_ZERO,           /// do not restore counter, always set to zero
+};
+
 /// All possible resolutions for the rotary encoder
 enum RotaryEncoderResolution {
   ROTARY_ENCODER_1_PULSE_PER_CYCLE =
@@ -40,6 +46,15 @@ class RotaryEncoderSensor : public sensor::Sensor, public Component {
   void set_pin_a(InternalGPIOPin *pin_a) { pin_a_ = pin_a; }
   void set_pin_b(InternalGPIOPin *pin_b) { pin_b_ = pin_b; }
 
+  /** Set the restore mode of the rotary encoder.
+   *
+   * By default (if possible) the last known counter state is restored. Otherwise the value 0 is used.
+   * Restoring the state can also be turned off.
+   *
+   * @param restore_mode The restore mode to use.
+   */
+  void set_restore_mode(RotaryEncoderRestoreMode restore_mode);
+
   /** Set the resolution of the rotary encoder.
    *
    * By default, this component will increment the counter by 1 with every A-B input cycle.
@@ -81,6 +96,8 @@ class RotaryEncoderSensor : public sensor::Sensor, public Component {
   InternalGPIOPin *pin_b_;
   GPIOPin *pin_i_{nullptr};  /// Index pin, if this is not nullptr, the counter will reset to 0 once this pin is HIGH.
   bool publish_initial_value_;
+  ESPPreferenceObject rtc_;
+  RotaryEncoderRestoreMode restore_mode_{ROTARY_ENCODER_RESTORE_DEFAULT_ZERO};
 
   RotaryEncoderSensorStore store_{};