forked from OpenPDU/openpdu-libs
452 lines
14 KiB
Python
452 lines
14 KiB
Python
"""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()
|