Add CH9329 Serial to HID support (#121)

* Add ch9329 plugin

* refactoring ch9329

* refactor ch9329 and cleanup

* refactoring

* fixing lint errors

* clarifying list type

kvmd/plugins/hid/ch9329/keyboard.py

@@ -0,0 +1,71 @@
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main PiKVM daemon.                                           #
+#                                                                            #
+#    Copyright (C) 2018-2022  Maxim Devaev <mdevaev@gmail.com>               #
+#                                                                            #
+#    This program is free software: you can redistribute it and/or modify    #
+#    it under the terms of the GNU General Public License as published by    #
+#    the Free Software Foundation, either version 3 of the License, or       #
+#    (at your option) any later version.                                     #
+#                                                                            #
+#    This program is distributed in the hope that it will be useful,         #
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of          #
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
+#    GNU General Public License for more details.                            #
+#                                                                            #
+#    You should have received a copy of the GNU General Public License       #
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
+#                                                                            #
+# ========================================================================== #
+
+from .... import aiomulti
+
+from ....keyboard.mappings import KEYMAP
+
+
+class Keyboard:
+    def __init__(self) -> None:
+
+        self.__notifier = aiomulti.AioProcessNotifier()
+        self.__leds = aiomulti.AioSharedFlags({
+            "num": False,
+            "caps": False,
+            "scroll": False,
+        }, self.__notifier, type=bool)
+
+        self.__active_keys: list[list] = []
+
+    def key(self, key: str, state: bool) -> list[int]:
+        if state:
+            self.__active_keys.append([key, self.__is_modifier(key)])
+        else:
+            self.__active_keys.remove([key, self.__is_modifier(key)])
+        return self.__key()
+
+    async def leds(self) -> dict:
+        leds = await self.__leds.get()
+        return leds
+
+    def set_leds(self, led_byte: int) -> None:
+        num = bool(led_byte & 1)
+        caps = bool((led_byte >> 1) & 1)
+        scroll = bool((led_byte >> 2) & 1)
+        self.__leds.update(num=num, caps=caps, scroll=scroll)
+
+    def __key(self) -> list[int]:
+        cmd = [0x00, 0x02, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
+        counter = 0
+        for key in self.__active_keys:
+            if key[1]:
+                cmd[3 + counter] = self.__keycode(key[0])
+            else:
+                cmd[5 + counter] = self.__keycode(key[0])
+            counter += 1
+        return cmd
+
+    def __keycode(self, key: str) -> int:
+        return KEYMAP[key].usb.code
+
+    def __is_modifier(self, key: str) -> bool:
+        return KEYMAP[key].usb.is_modifier