initial commit

usr/python2.7/site-packages/smbus2/__init__.py

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+from .smbus2 import SMBus, SMBusWrapper, i2c_msg
+
+__version__ = "0.2.0"

usr/python2.7/site-packages/smbus2/smbus2.py

@@ -0,0 +1,451 @@
+"""smbus2 - A drop-in replacement for smbus-cffi/smbus-python"""
+# The MIT License (MIT)
+# Copyright (c) 2017 Karl-Petter Lindegaard
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import os
+import sys
+from fcntl import ioctl
+from ctypes import c_uint32, c_uint8, c_uint16, c_char, POINTER, Structure, Array, Union, create_string_buffer
+
+
+# Commands from uapi/linux/i2c-dev.h
+I2C_SLAVE = 0x0703  # Use this slave address
+I2C_SLAVE_FORCE = 0x0706  # Use this slave address, even if it is already in use by a driver!
+I2C_FUNCS = 0x0705  # Get the adapter functionality mask
+I2C_RDWR  = 0x0707  # Combined R/W transfer (one STOP only)
+I2C_SMBUS = 0x0720  # SMBus transfer. Takes pointer to i2c_smbus_ioctl_data
+
+# SMBus transfer read or write markers from uapi/linux/i2c.h
+I2C_SMBUS_WRITE = 0
+I2C_SMBUS_READ = 1
+
+# Size identifiers uapi/linux/i2c.h
+I2C_SMBUS_BYTE = 1
+I2C_SMBUS_BYTE_DATA = 2
+I2C_SMBUS_WORD_DATA = 3
+I2C_SMBUS_BLOCK_DATA = 5  # Can't get this one to work on my Raspberry Pi
+I2C_SMBUS_I2C_BLOCK_DATA = 8
+I2C_SMBUS_BLOCK_MAX = 32
+
+# To determine what functionality is present (uapi/linux/i2c.h)
+I2C_FUNC_I2C = 0x00000001
+I2C_FUNC_10BIT_ADDR = 0x00000002
+I2C_FUNC_PROTOCOL_MANGLING = 0x00000004  # I2C_M_IGNORE_NAK etc.
+I2C_FUNC_SMBUS_PEC = 0x00000008
+I2C_FUNC_NOSTART = 0x00000010  # I2C_M_NOSTART
+I2C_FUNC_SLAVE = 0x00000020
+I2C_FUNC_SMBUS_BLOCK_PROC_CALL = 0x00008000  # SMBus 2.0
+I2C_FUNC_SMBUS_QUICK = 0x00010000
+I2C_FUNC_SMBUS_READ_BYTE = 0x00020000
+I2C_FUNC_SMBUS_WRITE_BYTE = 0x00040000
+I2C_FUNC_SMBUS_READ_BYTE_DATA = 0x00080000
+I2C_FUNC_SMBUS_WRITE_BYTE_DATA = 0x00100000
+I2C_FUNC_SMBUS_READ_WORD_DATA = 0x00200000
+I2C_FUNC_SMBUS_WRITE_WORD_DATA = 0x00400000
+I2C_FUNC_SMBUS_PROC_CALL = 0x00800000
+I2C_FUNC_SMBUS_READ_BLOCK_DATA = 0x01000000
+I2C_FUNC_SMBUS_WRITE_BLOCK_DATA = 0x02000000
+I2C_FUNC_SMBUS_READ_I2C_BLOCK = 0x04000000  # I2C-like block xfer
+I2C_FUNC_SMBUS_WRITE_I2C_BLOCK = 0x08000000  # w/ 1-byte reg. addr.
+
+# i2c_msg flags from uapi/linux/i2c.h
+I2C_M_RD = 0x0001
+
+# Pointer definitions
+LP_c_uint8 = POINTER(c_uint8)
+LP_c_uint16 = POINTER(c_uint16)
+LP_c_uint32 = POINTER(c_uint32)
+
+
+#############################################################
+# Type definitions as in i2c.h
+
+
+class i2c_smbus_data(Array):
+    """
+    Adaptation of the i2c_smbus_data union in i2c.h
+
+    Data for SMBus messages.
+    """
+    _length_ = I2C_SMBUS_BLOCK_MAX+2
+    _type_ = c_uint8
+
+
+class union_i2c_smbus_data(Union):
+    _fields_ = [
+        ("byte", c_uint8),
+        ("word", c_uint16),
+        ("block", i2c_smbus_data)
+    ]
+
+union_pointer_type = POINTER(union_i2c_smbus_data)
+
+
+class i2c_smbus_ioctl_data(Structure):
+    """
+    As defined in i2c-dev.h
+    """
+    _fields_ = [
+        ('read_write', c_uint8),
+        ('command', c_uint8),
+        ('size', c_uint32),
+        ('data', union_pointer_type)]
+    __slots__ = [name for name, type in _fields_]
+
+    @staticmethod
+    def create(read_write=I2C_SMBUS_READ, command=0, size=I2C_SMBUS_BYTE_DATA):
+        u = union_i2c_smbus_data()
+        return i2c_smbus_ioctl_data(
+            read_write=read_write, command=command, size=size,
+            data=union_pointer_type(u))
+
+
+#############################################################
+# Type definitions for i2c_rdwr combined transactions
+
+
+class i2c_msg(Structure):
+    """
+    As defined in i2c.h
+    """
+    _fields_ = [
+        ('addr', c_uint16),
+        ('flags', c_uint16),
+        ('len', c_uint16),
+        ('buf', POINTER(c_char))]
+    __slots__ = [name for name, type in _fields_]
+
+    def __iter__(self):
+        return i2c_msg_iter(self)
+
+    @staticmethod
+    def read(address, length):
+        """
+        Prepares an i2c read transaction
+        :param address: Slave address
+        :param length: Number of bytes to read
+        :return: New i2c_msg instance for read operation
+        :rtype: i2c_msg
+        """
+        arr = create_string_buffer(length)
+        return i2c_msg(
+            addr=address, flags=I2C_M_RD, len=length,
+            buf=arr)
+
+    @staticmethod
+    def write(address, buf):
+        """
+        Prepares an i2c write transaction
+        :param address: Slave address
+        :param buf: Bytes to write. Either list of values or string
+        :return: New i2c_msg instance for write operation
+        :rtype: i2c_msg
+        """
+        if sys.version_info.major >= 3:
+            if type(buf) is str:
+                buf = bytes(buf, 'UTF-8')
+            else:
+                buf = bytes(buf)
+        else:
+            if type(buf) is not str:
+                buf = ''.join([chr(x) for x in buf])
+        arr = create_string_buffer(buf, len(buf))
+        return i2c_msg(
+            addr=address, flags=0, len=len(arr),
+            buf=arr)
+
+
+class i2c_rdwr_ioctl_data(Structure):
+    """
+    As defined in i2c-dev.h
+    """
+    _fields_ = [
+        ('msgs', POINTER(i2c_msg)),
+        ('nmsgs', c_uint32)
+    ]
+    __slots__ = [name for name, type in _fields_]
+
+    @staticmethod
+    def create(*i2c_msg_instances):
+        """
+        Factory method for creating a i2c_rdwr_ioctl_data struct that can
+        be called with ioctl(fd, I2C_RDWR, data)
+        :param i2c_msg_instances: Up to 42 i2c_msg instances
+        :return:
+        :rtype: i2c_rdwr_ioctl_data
+        """
+        n_msg = len(i2c_msg_instances)
+        msg_array = (i2c_msg * n_msg)(*i2c_msg_instances)
+        return i2c_rdwr_ioctl_data(
+            msgs=msg_array,
+            nmsgs=n_msg
+        )
+
+class i2c_msg_iter:
+    """
+    i2c_msg iterator. For convenience.
+    """
+
+    def __init__(self, msg):
+        self.msg = msg
+        self.idx = 0
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self.idx < self.msg.len:
+            val = ord(self.msg.buf[self.idx])
+            self.idx += 1
+            return val
+        else:
+            raise StopIteration()
+
+    def next(self):
+        return self.__next__()
+
+#############################################################
+
+
+class SMBus(object):
+
+    def __init__(self, bus=None, force=False):
+        # type: (int, bool) -> None
+        """
+        Initialize and (optionally) open an i2c bus connection.
+        :param bus: i2c bus number (e.g. 0 or 1). If not given, a subsequent call to open() is required.
+        :param force: force using the slave address even when driver is already using it
+        :type force: Boolean
+        """
+        self.fd = None
+        self.funcs = 0
+        if bus is not None:
+            self.open(bus)
+        self.address = None
+        self.force = force
+
+    def open(self, bus):
+        # type: (int) -> None
+        """
+        Open a given i2c bus.
+        :param bus: i2c bus number (e.g. 0 or 1)
+        """
+        self.fd = os.open("/dev/i2c-{}".format(bus), os.O_RDWR)
+        self.funcs = self._get_funcs()
+
+    def close(self):
+        """
+        Close the i2c connection.
+        """
+        if self.fd:
+            os.close(self.fd)
+            self.fd = None
+
+    def _set_address(self, address):
+        # type: (int) -> None
+        """
+        Set i2c slave address to use for subsequent calls.
+        :param address:
+        """
+        if self.address != address:
+            self.address = address
+            if self.force:
+                ioctl(self.fd, I2C_SLAVE_FORCE, address)
+            else:
+                ioctl(self.fd, I2C_SLAVE, address)
+
+    def _get_funcs(self):
+        """
+        Returns a 32-bit value stating supported I2C functions.
+        :rtype: int
+        """
+        f = c_uint32()
+        ioctl(self.fd, I2C_FUNCS, f)
+        return f.value
+
+    def read_byte(self, i2c_addr):
+        # type: (int) -> int
+        """
+        Read a single byte from a device
+        :rtype: int
+        :param i2c_addr: i2c address
+        :return: Read byte value
+        """
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_READ, command=0, size=I2C_SMBUS_BYTE
+        )
+        ioctl(self.fd, I2C_SMBUS, msg)
+        return msg.data.contents.byte
+
+    def write_byte(self, i2c_addr, value):
+        # type: (int, int) -> None
+        """
+        Write a single byte to a device
+        :param i2c_addr: i2c address
+        :param value: value to write
+        """
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_WRITE, command=value, size=I2C_SMBUS_BYTE
+        )
+        ioctl(self.fd, I2C_SMBUS, msg)
+
+    def read_byte_data(self, i2c_addr, register):
+        # type: (int, int) -> int
+        """
+        Read a single byte from a designated register.
+        :rtype: int
+        :param i2c_addr: i2c address
+        :param register: Register to read
+        :return: Read byte value
+        """
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_READ, command=register, size=I2C_SMBUS_BYTE_DATA
+        )
+        ioctl(self.fd, I2C_SMBUS, msg)
+        return msg.data.contents.byte
+
+    def write_byte_data(self, i2c_addr, register, value):
+        # type: (int, int, int) -> None
+        """
+        Write a byte to a given register
+        :param i2c_addr: i2c address
+        :param register: Register to write to
+        :param value: Byte value to transmit
+        """
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_WRITE, command=register, size=I2C_SMBUS_BYTE_DATA
+        )
+        msg.data.contents.byte = value
+        ioctl(self.fd, I2C_SMBUS, msg)
+
+    def read_word_data(self, i2c_addr, register):
+        # type: (int, int) -> int
+        """
+        Read a single word (2 bytes) from a given register
+        :rtype: int
+        :param i2c_addr: i2c address
+        :param register: Register to read
+        :return: 2-byte word
+        """
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_READ, command=register, size=I2C_SMBUS_WORD_DATA
+        )
+        ioctl(self.fd, I2C_SMBUS, msg)
+        return msg.data.contents.word
+
+    def write_word_data(self, i2c_addr, register, value):
+        # type: (int, int, int) -> None
+        """
+        Write a byte to a given register
+        :param i2c_addr: i2c address
+        :param register: Register to write to
+        :param value: Word value to transmit
+        """
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_WRITE, command=register, size=I2C_SMBUS_WORD_DATA
+        )
+        msg.data.contents.word = value
+        ioctl(self.fd, I2C_SMBUS, msg)
+
+    def read_i2c_block_data(self, i2c_addr, register, length):
+        # type: (int, int, int) -> list
+        """
+        Read a block of byte data from a given register
+        :rtype: list
+        :param i2c_addr: i2c address
+        :param register: Start register
+        :param length: Desired block length
+        :return: List of bytes
+        """
+        if length > I2C_SMBUS_BLOCK_MAX:
+            raise ValueError("Desired block length over %d bytes" % I2C_SMBUS_BLOCK_MAX)
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_READ, command=register, size=I2C_SMBUS_I2C_BLOCK_DATA
+        )
+        msg.data.contents.byte = length
+        ioctl(self.fd, I2C_SMBUS, msg)
+        return msg.data.contents.block[1:length+1]
+
+    def write_i2c_block_data(self, i2c_addr, register, data):
+        # type: (int, int, list) -> None
+        """
+        Write a block of byte data to a given register
+        :param i2c_addr: i2c address
+        :param register: Start register
+        :param data: List of bytes
+        """
+        length = len(data)
+        if length > I2C_SMBUS_BLOCK_MAX:
+            raise ValueError("Data length cannot exceed %d bytes" % I2C_SMBUS_BLOCK_MAX)
+        self._set_address(i2c_addr)
+        msg = i2c_smbus_ioctl_data.create(
+            read_write=I2C_SMBUS_WRITE, command=register, size=I2C_SMBUS_I2C_BLOCK_DATA
+        )
+        msg.data.contents.block[0] = length
+        msg.data.contents.block[1:length + 1] = data
+        ioctl(self.fd, I2C_SMBUS, msg)
+
+    def i2c_rdwr(self, *i2c_msgs):
+        # type: (i2c_msg) -> None
+        """
+        Combine a series of i2c read and write operations in a single
+        transaction (with repeted start bits but no stop bits in between).
+        This method takes i2c_msg instances as input, which must be created
+        first with i2c_msg.create_read() or i2c_msg.create_write().
+        :type i2c_msgs: i2c_msg
+        :param i2c_msgs: One or more i2c_msg class instances.
+        :return: None
+        """
+        ioctl_data = i2c_rdwr_ioctl_data.create(*i2c_msgs)
+        ioctl(self.fd, I2C_RDWR, ioctl_data)
+
+
+class SMBusWrapper:
+    """
+    Wrapper class around the SMBus. Enables the user to wrap access to
+    the SMBus class in a "with" statement. Will automatically close the SMBus handle upon
+    exit of the with block.
+    """
+    def __init__(self, bus_number=0, auto_cleanup=True, force=False):
+        """
+        :param auto_cleanup: Close bus when leaving scope.
+        :type auto_cleanup: Boolean
+        :param force: Force using the slave address even when driver is already using it.
+        :type force: Boolean
+        """
+        self.bus_number = bus_number
+        self.auto_cleanup = auto_cleanup
+        self.force = force
+
+    def __enter__(self):
+        self.bus = SMBus(bus=self.bus_number, force=self.force)
+        return self.bus
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if self.auto_cleanup:
+            self.bus.close()