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[Adafruit_Blinka-hackapet.git] / src / adafruit_blinka / microcontroller / generic_linux / i2c.py

diff --git a/src/adafruit_blinka/microcontroller/generic_linux/i2c.py b/src/adafruit_blinka/microcontroller/generic_linux/i2c.py
index ed8c8b8f7ed0860694d8a6e9200034b519e7e854..b6f2fa36885c46a6f53c3aaceff0af42f0b7833d 100644 (file)
--- a/src/adafruit_blinka/microcontroller/generic_linux/i2c.py
+++ b/src/adafruit_blinka/microcontroller/generic_linux/i2c.py
@@ -1,30 +1,50 @@
-import Adafruit_PureIO.smbus as smbus
-import time
+# SPDX-FileCopyrightText: 2021 Melissa LeBlanc-Williams for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+"""Generic Linux I2C class using PureIO's smbus class"""
+
+import warnings
+from Adafruit_PureIO import smbus
+
 
 class I2C:
+    """
+    I2C class
+
+    Baudrate has no effect on Linux systems. The argument is only there for compatibility.
+    """
+
     MASTER = 0
     SLAVE = 1
     _baudrate = None
     _mode = None
     _i2c_bus = None
 
+    # pylint: disable=unused-argument
     def __init__(self, bus_num, mode=MASTER, baudrate=None):
         if mode != self.MASTER:
             raise NotImplementedError("Only I2C Master supported!")
         _mode = self.MASTER
 
-        #if baudrate != None:
-        #    print("I2C frequency is not settable in python, ignoring!")
-        
+        if baudrate is not None:
+            warnings.warn(
+                "I2C frequency is not settable in python, ignoring!", RuntimeWarning
+            )
+
         try:
             self._i2c_bus = smbus.SMBus(bus_num)
         except FileNotFoundError:
-            raise RuntimeError("I2C Bus #%d not found, check if enabled in config!" % bus_num)
+            raise RuntimeError(
+                "I2C Bus #%d not found, check if enabled in config!" % bus_num
+            ) from RuntimeError
+
+    # pylint: enable=unused-argument
 
     def scan(self):
-        """Try to read a byte from each address, if you get an OSError it means the device isnt there"""
+        """Try to read a byte from each address, if you get an OSError
+        it means the device isnt there"""
         found = []
-        for addr in range(0,0x80):
+        for addr in range(0, 0x80):
             try:
                 self._i2c_bus.read_byte(addr)
             except OSError:
@@ -32,24 +52,41 @@ class I2C:
             found.append(addr)
         return found
 
+    # pylint: disable=unused-argument
     def writeto(self, address, buffer, *, start=0, end=None, stop=True):
+        """Write data from the buffer to an address"""
         if end is None:
             end = len(buffer)
         self._i2c_bus.write_bytes(address, buffer[start:end])
 
     def readfrom_into(self, address, buffer, *, start=0, end=None, stop=True):
+        """Read data from an address and into the buffer"""
         if end is None:
             end = len(buffer)
-        
-        readin = self._i2c_bus.read_bytes(address, end-start)
-        for i in range(end-start):
-            buffer[i+start] = readin[i]
 
-    def writeto_then_readfrom(self, address, buffer_out, buffer_in, *,
-                       out_start=0, out_end=None,
-                       in_start=0, in_end=None, stop=False):
+        readin = self._i2c_bus.read_bytes(address, end - start)
+        for i in range(end - start):
+            buffer[i + start] = readin[i]
+
+    # pylint: enable=unused-argument
+
+    def writeto_then_readfrom(
+        self,
+        address,
+        buffer_out,
+        buffer_in,
+        *,
+        out_start=0,
+        out_end=None,
+        in_start=0,
+        in_end=None,
+        stop=False,
+    ):
+        """Write data from buffer_out to an address and then
+        read data from an address and into buffer_in
+        """
         if out_end is None:
-            out_end = len(buffer_out)        
+            out_end = len(buffer_out)
         if in_end is None:
             in_end = len(buffer_in)
         if stop:
@@ -58,7 +95,8 @@ class I2C:
             self.readfrom_into(address, buffer_in, start=in_start, end=in_end)
         else:
             # To generate without a stop, do in one block transaction
-            readin = self._i2c_bus.read_i2c_block_data(address, buffer_out[out_start:out_end], in_end-in_start)
-            for i in range(in_end-in_start):
-                buffer_in[i+in_start] = readin[i]
-
+            readin = self._i2c_bus.read_i2c_block_data(
+                address, buffer_out[out_start:out_end], in_end - in_start
+            )
+            for i in range(in_end - in_start):
+                buffer_in[i + in_start] = readin[i]