Implement detachFromHost() and attachToHost()

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/kaleidoscope/hardware/ErgoDox.cpp

@@ -217,6 +217,14 @@ void ErgoDox::debounceRow(uint8_t change, uint8_t row) {
   }
 }
 
+void ErgoDox::detachFromHost() {
+  UDCON |= (1 << DETACH);
+}
+
+void ErgoDox::attachToHost() {
+  UDCON &= ~(1 << DETACH);
+}
+
 }
 }
 

src/kaleidoscope/hardware/ErgoDox.h

@@ -63,6 +63,17 @@ class ErgoDox {
   void actOnMatrixScan(void);
   void setup();
 
+  /** Detaching from / attaching to the host.
+   *
+   * These two functions should detach the device from (or attach it to) the
+   * host, preferably without rebooting the device. Their purpose is to allow
+   * one to do some configuration inbetween, so the re-attach happens with
+   * different properties. The device remains powered between these operations,
+   * only the connection to the host gets severed.
+   */
+  void detachFromHost();
+  void attachToHost();
+
   /* Key masking
    * -----------
    *