Merge pull request #807 from brentru/force-mcp

[Adafruit_Blinka-hackapet.git] / src / adafruit_blinka / microcontroller / am335x / sysfs_pwmout.py

diff --git a/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py b/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py
index 2ba135927da79d86e24ae76fd758e9fed9383c63..dd96c53b36fa8ec458cd944b1d663b6203e8389e 100644 (file)
--- a/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py
+++ b/src/adafruit_blinka/microcontroller/am335x/sysfs_pwmout.py
@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
 """
 Much code from https://github.com/vsergeev/python-periphery/blob/master/periphery/pwm.py
 Copyright (c) 2015-2016 vsergeev / Ivan (Vanya) A. Sergeev
@@ -9,7 +12,8 @@ import os
 try:
     from microcontroller.pin import pwmOuts
 except ImportError:
-    raise RuntimeError("No PWM outputs defined for this board")
+    raise RuntimeError("No PWM outputs defined for this board") from ImportError
+
 
 # pylint: disable=unnecessary-pass
 class PWMError(IOError):
@@ -101,11 +105,11 @@ class PWMOut:
         if not os.path.isdir(pin_path):
             try:
                 with open(
-                    os.path.join(channel_path, self._export_path), "w"
+                    os.path.join(channel_path, self._export_path), "w", encoding="utf-8"
                 ) as f_export:
                     f_export.write("%d\n" % self._pwmpin)
             except IOError as e:
-                raise PWMError(e.errno, "Exporting PWM pin: " + e.strerror)
+                raise PWMError(e.errno, "Exporting PWM pin: " + e.strerror) from IOError
 
         # Look up the period, for fast duty cycle updates
         self._period = self._get_period()
@@ -131,11 +135,15 @@ class PWMOut:
                 try:
                     # unexport_path = os.path.join(channel_path, self._unexport_path)
                     with open(
-                        os.path.join(channel_path, self._unexport_path), "w"
+                        os.path.join(channel_path, self._unexport_path),
+                        "w",
+                        encoding="utf-8",
                     ) as f_unexport:
                         f_unexport.write("%d\n" % self._pwmpin)
                 except IOError as e:
-                    raise PWMError(e.errno, "Unexporting PWM pin: " + e.strerror)
+                    raise PWMError(
+                        e.errno, "Unexporting PWM pin: " + e.strerror
+                    ) from IOError
         except Exception as e:
             # due to a race condition for which I have not yet been
             # able to find the root cause, deinit() often fails
@@ -168,7 +176,7 @@ class PWMOut:
             attr,
         )
 
-        with open(path, "w") as f_attr:
+        with open(path, "w", encoding="utf-8") as f_attr:
             f_attr.write(value + "\n")
 
     def _read_pin_attr(self, attr):
@@ -182,7 +190,7 @@ class PWMOut:
             attr,
         )
 
-        with open(path, "r") as f_attr:
+        with open(path, "r", encoding="utf-8") as f_attr:
             return f_attr.read().strip()
 
     # Mutable properties
@@ -192,7 +200,9 @@ class PWMOut:
         try:
             period_ns = int(period_ns)
         except ValueError:
-            raise PWMError(None, 'Unknown period value: "%s"' % period_ns)
+            raise PWMError(
+                None, 'Unknown period value: "%s"' % period_ns
+            ) from ValueError
 
         # Convert period from nanoseconds to seconds
         period = period_ns / 1e9
@@ -230,7 +240,9 @@ class PWMOut:
         try:
             duty_cycle_ns = int(duty_cycle_ns)
         except ValueError:
-            raise PWMError(None, 'Unknown duty cycle value: "%s"' % duty_cycle_ns)
+            raise PWMError(
+                None, 'Unknown duty cycle value: "%s"' % duty_cycle_ns
+            ) from ValueError
 
         # Convert duty cycle from nanoseconds to seconds
         duty_cycle = duty_cycle_ns / 1e9