Added driver for xh_hk4401 4 port HDMI/USB KVM (#69)

* Added driver for xh_hk4401 4 port HDMI/USB KVM

* Removed trailing whitespace

* Changed xh_hk4401 channel numbers

Used 0-3 to match other KVM plugins instead of the 1-4 numbering the KVM
uses.

kvmd/plugins/ugpio/xh_hk4401.py

@@ -0,0 +1,192 @@
+# ========================================================================== #
+#                                                                            #
+#    KVMD - The main PiKVM daemon.                                           #
+#                                                                            #
+#    Copyright (C) 2018-2021  Maxim Devaev <mdevaev@gmail.com>               #
+#                  2021-2021  Sebastian Goscik <sebastian.goscik@live.co.uk> #
+#                                                                            #
+#    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/>.  #
+#                                                                            #
+# ========================================================================== #
+
+
+import re
+import multiprocessing
+import functools
+import errno
+import time
+
+from typing import Tuple
+from typing import Dict
+from typing import Callable
+from typing import Optional
+from typing import Any
+
+import serial
+
+from ...logging import get_logger
+
+from ... import aiotools
+from ... import aiomulti
+from ... import aioproc
+
+from ...yamlconf import Option
+
+from ...validators.basic import valid_number
+from ...validators.basic import valid_float_f01
+from ...validators.os import valid_abs_path
+from ...validators.hw import valid_tty_speed
+
+from . import GpioDriverOfflineError
+from . import BaseUserGpioDriver
+
+
+# =====
+class Plugin(BaseUserGpioDriver):  # pylint: disable=too-many-instance-attributes
+    def __init__(
+        self,
+        instance_name: str,
+        notifier: aiotools.AioNotifier,
+
+        device_path: str,
+        speed: int,
+        read_timeout: float,
+    ) -> None:
+
+        super().__init__(instance_name, notifier)
+
+        self.__device_path = device_path
+        self.__speed = speed
+        self.__read_timeout = read_timeout
+
+        self.__ctl_queue: "multiprocessing.Queue[int]" = multiprocessing.Queue()
+        self.__channel_queue: "multiprocessing.Queue[Optional[int]]" = multiprocessing.Queue()
+        self.__channel: Optional[int] = -1
+
+        self.__proc: Optional[multiprocessing.Process] = None
+        self.__stop_event = multiprocessing.Event()
+
+    @classmethod
+    def get_plugin_options(cls) -> Dict:
+        return {
+            "device":       Option("",     type=valid_abs_path, unpack_as="device_path"),
+            "speed":        Option(19200,  type=valid_tty_speed),
+            "read_timeout": Option(2.0,    type=valid_float_f01),
+        }
+
+    @classmethod
+    def get_pin_validator(cls) -> Callable[[Any], Any]:
+        return functools.partial(valid_number, min=0, max=3, name="XH-HK4401 channel")
+
+    def prepare(self) -> None:
+        assert self.__proc is None
+        self.__proc = multiprocessing.Process(target=self.__serial_worker, daemon=True)
+        self.__proc.start()
+
+    async def run(self) -> None:
+        while True:
+            (got, channel) = await aiomulti.queue_get_last(self.__channel_queue, 1)
+            if got and self.__channel != channel:
+                self.__channel = channel
+                await self._notifier.notify()
+
+    async def cleanup(self) -> None:
+        if self.__proc is not None:
+            if self.__proc.is_alive():
+                get_logger(0).info("Stopping %s daemon ...", self)
+                self.__stop_event.set()
+            if self.__proc.is_alive() or self.__proc.exitcode is not None:
+                self.__proc.join()
+
+    async def read(self, pin: str) -> bool:
+        if not self.__is_online():
+            raise GpioDriverOfflineError(self)
+        return (self.__channel == int(pin))
+
+    async def write(self, pin: str, state: bool) -> None:
+        if not self.__is_online():
+            raise GpioDriverOfflineError(self)
+        if state:
+            self.__ctl_queue.put_nowait(int(pin))
+
+    # =====
+
+    def __is_online(self) -> bool:
+        return (
+            self.__proc is not None
+            and self.__proc.is_alive()
+            and self.__channel is not None
+        )
+
+    def __serial_worker(self) -> None:
+        logger = aioproc.settle(str(self), f"gpio-xh-hk4401-{self._instance_name}")
+        while not self.__stop_event.is_set():
+            try:
+                with self.__get_serial() as tty:
+                    data = b""
+                    self.__channel_queue.put_nowait(-1)
+
+                    # Wait for first port heartbeat to set correct channel (~2 sec max)
+                    while True:
+                        (channel, data) = self.__recv_channel(tty, data)
+                        if channel is not None:
+                            self.__channel_queue.put_nowait(channel)
+                            break
+
+                    while not self.__stop_event.is_set():
+                        (channel, data) = self.__recv_channel(tty, data)
+                        if channel is not None:
+                            self.__channel_queue.put_nowait(channel)
+
+                        (got, channel) = aiomulti.queue_get_last_sync(self.__ctl_queue, 0.1)  # type: ignore
+                        if got:
+                            assert channel is not None
+                            self.__send_channel(tty, channel)
+
+            except Exception as err:
+                self.__channel_queue.put_nowait(None)
+                if isinstance(err, serial.SerialException) and err.errno == errno.ENOENT:  # pylint: disable=no-member
+                    logger.error("Missing %s serial device: %s", self, self.__device_path)
+                else:
+                    logger.exception("Unexpected %s error", self)
+                time.sleep(1)
+
+    def __get_serial(self) -> serial.Serial:
+        return serial.Serial(self.__device_path, self.__speed, timeout=self.__read_timeout)
+
+    def __recv_channel(self, tty: serial.Serial, data: bytes) -> Tuple[Optional[int], bytes]:
+        channel: Optional[int] = None
+        if tty.in_waiting:
+            data += tty.read_all()
+            found = re.findall(b"AG0[0-4]gA", data)
+            data = data[-12:]
+
+            if found:
+                try:
+                    channel = int(found[-1][2:4])-1
+                except Exception:
+                    return (None, data)
+                assert 0 <= channel <= 3
+        return (channel, data)
+
+    def __send_channel(self, tty: serial.Serial, channel: int) -> None:
+        assert 0 <= channel <= 3
+        cmd = "SW{port}\r\nAG{port:02d}gA".format(port=channel+1).encode()
+        tty.write(cmd)
+        tty.flush()
+
+    def __str__(self) -> str:
+        return f"Xh_hk4401({self._instance_name})"
+
+    __repr__ = __str__