259 lines
8.3 KiB
Python
259 lines
8.3 KiB
Python
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#! python
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#
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# Backend for Silicon Labs CP2110/4 HID-to-UART devices.
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#
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# This file is part of pySerial. https://github.com/pyserial/pyserial
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# (C) 2001-2015 Chris Liechti <cliechti@gmx.net>
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# (C) 2019 Google LLC
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#
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# SPDX-License-Identifier: BSD-3-Clause
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# This backend implements support for HID-to-UART devices manufactured
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# by Silicon Labs and marketed as CP2110 and CP2114. The
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# implementation is (mostly) OS-independent and in userland. It relies
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# on cython-hidapi (https://github.com/trezor/cython-hidapi).
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# The HID-to-UART protocol implemented by CP2110/4 is described in the
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# AN434 document from Silicon Labs:
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# https://www.silabs.com/documents/public/application-notes/AN434-CP2110-4-Interface-Specification.pdf
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# TODO items:
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# - rtscts support is configured for hardware flow control, but the
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# signaling is missing (AN434 suggests this is done through GPIO).
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# - Cancelling reads and writes is not supported.
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# - Baudrate validation is not implemented, as it depends on model and configuration.
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import struct
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import threading
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try:
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import urlparse
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except ImportError:
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import urllib.parse as urlparse
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try:
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import Queue
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except ImportError:
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import queue as Queue
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import hid # hidapi
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import serial
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from serial.serialutil import SerialBase, SerialException, PortNotOpenError, to_bytes, Timeout
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# Report IDs and related constant
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_REPORT_GETSET_UART_ENABLE = 0x41
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_DISABLE_UART = 0x00
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_ENABLE_UART = 0x01
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_REPORT_SET_PURGE_FIFOS = 0x43
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_PURGE_TX_FIFO = 0x01
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_PURGE_RX_FIFO = 0x02
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_REPORT_GETSET_UART_CONFIG = 0x50
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_REPORT_SET_TRANSMIT_LINE_BREAK = 0x51
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_REPORT_SET_STOP_LINE_BREAK = 0x52
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class Serial(SerialBase):
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# This is not quite correct. AN343 specifies that the minimum
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# baudrate is different between CP2110 and CP2114, and it's halved
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# when using non-8-bit symbols.
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BAUDRATES = (300, 375, 600, 1200, 1800, 2400, 4800, 9600, 19200,
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38400, 57600, 115200, 230400, 460800, 500000, 576000,
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921600, 1000000)
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def __init__(self, *args, **kwargs):
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self._hid_handle = None
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self._read_buffer = None
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self._thread = None
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super(Serial, self).__init__(*args, **kwargs)
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def open(self):
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if self._port is None:
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raise SerialException("Port must be configured before it can be used.")
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if self.is_open:
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raise SerialException("Port is already open.")
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self._read_buffer = Queue.Queue()
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self._hid_handle = hid.device()
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try:
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portpath = self.from_url(self.portstr)
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self._hid_handle.open_path(portpath)
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except OSError as msg:
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raise SerialException(msg.errno, "could not open port {}: {}".format(self._port, msg))
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try:
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self._reconfigure_port()
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except:
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try:
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self._hid_handle.close()
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except:
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pass
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self._hid_handle = None
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raise
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else:
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self.is_open = True
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self._thread = threading.Thread(target=self._hid_read_loop)
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self._thread.setDaemon(True)
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self._thread.setName('pySerial CP2110 reader thread for {}'.format(self._port))
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self._thread.start()
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def from_url(self, url):
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parts = urlparse.urlsplit(url)
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if parts.scheme != "cp2110":
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raise SerialException(
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'expected a string in the forms '
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'"cp2110:///dev/hidraw9" or "cp2110://0001:0023:00": '
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'not starting with cp2110:// {{!r}}'.format(parts.scheme))
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if parts.netloc: # cp2100://BUS:DEVICE:ENDPOINT, for libusb
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return parts.netloc.encode('utf-8')
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return parts.path.encode('utf-8')
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def close(self):
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self.is_open = False
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if self._thread:
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self._thread.join(1) # read timeout is 0.1
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self._thread = None
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self._hid_handle.close()
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self._hid_handle = None
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def _reconfigure_port(self):
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parity_value = None
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if self._parity == serial.PARITY_NONE:
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parity_value = 0x00
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elif self._parity == serial.PARITY_ODD:
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parity_value = 0x01
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elif self._parity == serial.PARITY_EVEN:
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parity_value = 0x02
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elif self._parity == serial.PARITY_MARK:
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parity_value = 0x03
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elif self._parity == serial.PARITY_SPACE:
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parity_value = 0x04
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else:
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raise ValueError('Invalid parity: {!r}'.format(self._parity))
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if self.rtscts:
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flow_control_value = 0x01
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else:
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flow_control_value = 0x00
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data_bits_value = None
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if self._bytesize == 5:
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data_bits_value = 0x00
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elif self._bytesize == 6:
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data_bits_value = 0x01
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elif self._bytesize == 7:
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data_bits_value = 0x02
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elif self._bytesize == 8:
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data_bits_value = 0x03
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else:
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raise ValueError('Invalid char len: {!r}'.format(self._bytesize))
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stop_bits_value = None
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if self._stopbits == serial.STOPBITS_ONE:
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stop_bits_value = 0x00
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elif self._stopbits == serial.STOPBITS_ONE_POINT_FIVE:
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stop_bits_value = 0x01
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elif self._stopbits == serial.STOPBITS_TWO:
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stop_bits_value = 0x01
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else:
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raise ValueError('Invalid stop bit specification: {!r}'.format(self._stopbits))
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configuration_report = struct.pack(
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'>BLBBBB',
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_REPORT_GETSET_UART_CONFIG,
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self._baudrate,
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parity_value,
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flow_control_value,
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data_bits_value,
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stop_bits_value)
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self._hid_handle.send_feature_report(configuration_report)
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self._hid_handle.send_feature_report(
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bytes((_REPORT_GETSET_UART_ENABLE, _ENABLE_UART)))
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self._update_break_state()
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@property
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def in_waiting(self):
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return self._read_buffer.qsize()
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def reset_input_buffer(self):
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if not self.is_open:
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raise PortNotOpenError()
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self._hid_handle.send_feature_report(
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bytes((_REPORT_SET_PURGE_FIFOS, _PURGE_RX_FIFO)))
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# empty read buffer
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while self._read_buffer.qsize():
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self._read_buffer.get(False)
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def reset_output_buffer(self):
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if not self.is_open:
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raise PortNotOpenError()
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self._hid_handle.send_feature_report(
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bytes((_REPORT_SET_PURGE_FIFOS, _PURGE_TX_FIFO)))
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def _update_break_state(self):
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if not self._hid_handle:
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raise PortNotOpenError()
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if self._break_state:
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self._hid_handle.send_feature_report(
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bytes((_REPORT_SET_TRANSMIT_LINE_BREAK, 0)))
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else:
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# Note that while AN434 states "There are no data bytes in
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# the payload other than the Report ID", either hidapi or
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# Linux does not seem to send the report otherwise.
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self._hid_handle.send_feature_report(
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bytes((_REPORT_SET_STOP_LINE_BREAK, 0)))
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def read(self, size=1):
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if not self.is_open:
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raise PortNotOpenError()
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data = bytearray()
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try:
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timeout = Timeout(self._timeout)
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while len(data) < size:
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if self._thread is None:
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raise SerialException('connection failed (reader thread died)')
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buf = self._read_buffer.get(True, timeout.time_left())
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if buf is None:
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return bytes(data)
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data += buf
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if timeout.expired():
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break
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except Queue.Empty: # -> timeout
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pass
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return bytes(data)
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def write(self, data):
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if not self.is_open:
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raise PortNotOpenError()
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data = to_bytes(data)
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tx_len = len(data)
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while tx_len > 0:
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to_be_sent = min(tx_len, 0x3F)
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report = to_bytes([to_be_sent]) + data[:to_be_sent]
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self._hid_handle.write(report)
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data = data[to_be_sent:]
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tx_len = len(data)
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def _hid_read_loop(self):
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try:
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while self.is_open:
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data = self._hid_handle.read(64, timeout_ms=100)
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if not data:
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continue
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data_len = data.pop(0)
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assert data_len == len(data)
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self._read_buffer.put(bytearray(data))
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finally:
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self._thread = None
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