Optimization: remove read/write from SPI device and return SPI bus on context manager enter.

Author: tdicola

adafruit_bus_device/spi_device.py

@@ -51,45 +51,13 @@ def __init__(self, spi, chip_select, baudrate=100000, polarity=0, phase=0):
  self.chip_select = chip_select
  self.chip_select.switch_to_output(value=True)
 
- def read(self, buffer, **kwargs):
- """
- Read into ``buffer`` from the device. The number of bytes read will be the
- length of ``buffer``.
-
- If ``start`` or ``end`` is provided, then the buffer will be sliced
- as if ``buffer[start:end]``. This will not cause an allocation like
- ``buffer[start:end]`` will so it saves memory.
-
- :param bytearray buffer: buffer to write into
- :param int start: Index to start writing at
- :param int end: Index to write up to but not include
- """
- self.spi.read(buffer, **kwargs)
-
- def write(self, buffer, **kwargs):
- """
- Write the bytes from ``buffer`` to the device. Transmits a stop bit if
- ``stop`` is set.
-
- If ``start`` or ``end`` is provided, then the buffer will be sliced
- as if ``buffer[start:end]``. This will not cause an allocation like
- ``buffer[start:end]`` will so it saves memory.
-
- :param bytearray buffer: buffer containing the bytes to write
- :param int start: Index to start writing from
- :param int end: Index to read up to but not include
- :param bool stop: If true, output an I2C stop condition after the
- buffer is written
- """
- self.spi.write(buffer, **kwargs)
-
  def __enter__(self):
  while not self.spi.try_lock():
  pass
  self.spi.configure(baudrate=self.baudrate, polarity=self.polarity,
  phase=self.phase)
  self.chip_select.value = False
- return self
+ return self.spi
 
  def __exit__(self, *exc):
  self.chip_select.value = True