Merge pull request #540 from ezio-melotti/close-mcp2221

[Adafruit_Blinka-hackapet.git] / src / adafruit_blinka / microcontroller / mcp2221 / mcp2221.py

diff --git a/src/adafruit_blinka/microcontroller/mcp2221/mcp2221.py b/src/adafruit_blinka/microcontroller/mcp2221/mcp2221.py
index 66d406dd902247aa1769cd76cdf4893191f906f1..5ff027ab2803df4957508ee388cef9016c1f80e8 100644 (file)
--- a/src/adafruit_blinka/microcontroller/mcp2221/mcp2221.py
+++ b/src/adafruit_blinka/microcontroller/mcp2221/mcp2221.py
@@ -1,12 +1,17 @@
+# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
 """Chip Definition for MCP2221"""
 
 import os
 import time
+import atexit
+
 import hid
 
 # Here if you need it
 MCP2221_HID_DELAY = float(os.environ.get("BLINKA_MCP2221_HID_DELAY", 0))
-# Use to set delay between reset and device reopen
+# Use to set delay between reset and device reopen. if negative, don't reset at all
 MCP2221_RESET_DELAY = float(os.environ.get("BLINKA_MCP2221_RESET_DELAY", 0.5))
 
 # from the C driver
@@ -51,12 +56,23 @@ class MCP2221:
     def __init__(self):
         self._hid = hid.device()
         self._hid.open(MCP2221.VID, MCP2221.PID)
-        self._reset()
+        # make sure the device gets closed before exit
+        atexit.register(self.close)
+        if MCP2221_RESET_DELAY >= 0:
+            self._reset()
         self._gp_config = [0x07] * 4  # "don't care" initial value
         for pin in range(4):
             self.gp_set_mode(pin, self.GP_GPIO)  # set to GPIO mode
             self.gpio_set_direction(pin, 1)  # set to INPUT
 
+    def close(self):
+        """Close the hid device. Does nothing if the device is not open."""
+        self._hid.close()
+
+    def __del__(self):
+        # try to close the device before destroying the instance
+        self.close()
+
     def _hid_xfer(self, report, response=True):
         """Perform HID Transfer"""
         # first byte is report ID, which =0 for MCP2221
@@ -188,7 +204,7 @@ class MCP2221:
             # bus release will need "a few hundred microseconds"
             time.sleep(0.001)
 
-    # pylint: disable=too-many-arguments
+    # pylint: disable=too-many-arguments,too-many-branches
     def _i2c_write(self, cmd, address, buffer, start=0, end=None):
         if self._i2c_state() != 0x00:
             self._i2c_cancel()
@@ -197,7 +213,7 @@ class MCP2221:
         length = end - start
         retries = 0
 
-        while (end - start) > 0:
+        while (end - start) > 0 or not buffer:
             chunk = min(end - start, MCP2221_MAX_I2C_DATA_LEN)
             # write out current chunk
             resp = self._hid_xfer(
@@ -222,6 +238,8 @@ class MCP2221:
             # yay chunk sent!
             while self._i2c_state() == RESP_I2C_PARTIALDATA:
                 time.sleep(0.001)
+            if not buffer:
+                break
             start += chunk
             retries = 0
 
@@ -284,6 +302,8 @@ class MCP2221:
                     continue
                 if resp[2] in (RESP_READ_COMPL, RESP_READ_PARTIAL):
                     break
+            else:
+                raise RuntimeError("I2C read error: max retries reached.")
 
             # move data into buffer
             chunk = min(end - start, 60)
@@ -293,7 +313,7 @@ class MCP2221:
 
     # pylint: enable=too-many-arguments
 
-    def i2c_configure(self, baudrate=100000):
+    def _i2c_configure(self, baudrate=100000):
         """Configure I2C"""
         self._hid_xfer(
             bytes(
@@ -324,7 +344,7 @@ class MCP2221:
         out_start=0,
         out_end=None,
         in_start=0,
-        in_end=None
+        in_end=None,
     ):
         """Write data from buffer_out to an address and then
         read data from an address and into buffer_in