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#
# Copyright 2018 Ettus Research, a National Instruments Company
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
"""
Utilities for i2c lookups
"""
import pyudev
from usrp_mpm.sys_utils.udev import get_device_from_dt_symbol
def _get_i2c_adapter_from_parent(parent, context):
"""
Helper to get the i2c adapter from a given parent device.
This logic is common for different device lookup methods.
"""
if not parent:
return None
devices = list(context.list_devices(parent=parent, subsystem="i2c-dev"))
properties = [dict(d.properties) for d in devices]
# The i2c-adapter will have the lowest minor number
# FIXME: This likely isn't API--It just happens to work as of this writing
chosen = min([(int(p['MINOR']), p['DEVNAME']) for p in properties])
return chosen[1]
def of_get_i2c_adapter(of_name):
"""
Return bus adapter device for given device tree name. To use the OF_NAME
for matching (as this function does), it must be a unique property in the
device tree (and this must be a device-tree platform).
The return value is a string, e.g. '/dev/i2c-0'. If nothing is found, it'll
return None.
"""
# If has i2c-dev, follow to grab i2c-%d node
context = pyudev.Context()
parents = list(context.list_devices(subsystem="i2c-adapter", OF_NAME=of_name))
if len(parents) > 1:
raise RuntimeError("Non-unique OF_NAME when getting i2c bus id")
if len(parents) == 0:
return None
parent = parents[0]
return _get_i2c_adapter_from_parent(parent, context)
def dt_symbol_get_i2c_bus(symbol):
"""
Return i2c bus associated with the given device tree symbol
The return value is a string, e.g. '/dev/i2c-0'. If nothing is found, it'll
return None.
"""
context = pyudev.Context()
parent = get_device_from_dt_symbol(symbol, subsystem='i2c', context=context)
return _get_i2c_adapter_from_parent(parent, context)
def sysname_get_i2c_adapter(sys_name):
"""
Return bus adapter device for given device tree sys_name.
The return value is a string, e.g. '/dev/i2c-0'. If nothing is found, it'll
return None.
"""
parent = sysname_get_i2c_parent(sys_name)
return _get_i2c_adapter_from_parent(parent, pyudev.Context())
def sysname_get_i2c_parent(sys_name):
"""
Returns the parent of an i2c adapter found by sys_name
"""
# If has i2c-dev, follow to grab i2c-%d node
context = pyudev.Context()
parents = list(context.list_devices(subsystem="i2c-adapter", sys_name=sys_name))
if len(parents) > 1:
raise RuntimeError("Non-unique sys_name when getting i2c bus id")
if len(parents) == 0:
return None
return parents[0]
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