blob: 7da5177f828e5612602be9b0fd12ffc48cb46a15 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
|
#
# Copyright 2018 Ettus Research, a National Instruments Company
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
"""
Utilities for i2c lookups
"""
import pyudev
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]
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]
|
