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#
# Copyright 2017 Ettus Research, a National Instruments Company
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
"""
Manipulation of device tree overlays (Linux kernel)
"""
import os
from usrp_mpm.mpmlog import get_logger
SYSFS_OVERLAY_BASE_DIR = '/sys/kernel/config/device-tree/overlays'
OVERLAY_DEFAULT_PATH = '/lib/firmware'
def get_overlay_attrs(overlay_name):
"""
List those attributes that are connected to an overlay entry in a sysfs
node.
"""
overlay_path = os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name)
attrs = {}
for attr_name in os.listdir(overlay_path):
try:
attr_val = open(
os.path.join(overlay_path, attr_name), 'r'
).read().strip()
except OSError:
pass
if len(attr_val):
attrs[attr_name] = attr_val
return attrs
def is_applied(overlay_name):
"""
Returns True if the overlay is already applied, False if not.
"""
try:
return open(
os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name, 'status')
).read().strip() == 'applied'
except IOError:
return False
def list_overlays(applied_only=False):
"""
List all registered kernel modules. Returns a dict of dicts:
{
'<overlay_name>': {
# attributes
},
}
All the attributes come from sysfs. See get_overlay_attrs().
applied_only -- Only return those overlays that are already applied.
"""
return {
overlay_name: get_overlay_attrs(overlay_name)
for overlay_name in os.listdir(SYSFS_OVERLAY_BASE_DIR)
if not applied_only \
or get_overlay_attrs(overlay_name).get('status') == 'applied'
}
def list_available_overlays(path=None):
"""
List available overlay files (dtbo)
"""
path = path or OVERLAY_DEFAULT_PATH
return [x.strip()[:-5] for x in os.listdir(path) if x.endswith('.dtbo')]
def apply_overlay(overlay_name):
"""
Applies the given overlay. Does not check if the overlay is loaded.
"""
get_logger("DTO").trace("Applying overlay `{}'...".format(overlay_name))
overlay_path = os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name)
if not os.path.exists(overlay_path):
os.mkdir(overlay_path)
open(
os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name, 'path'), 'w'
).write("{}.dtbo".format(overlay_name))
def apply_overlay_safe(overlay_name):
"""
Only apply an overlay if it's not yet applied.
Finally, checks that the overlay was applied and throws an exception if not.
"""
if is_applied(overlay_name):
get_logger("DTO").debug(
"Overlay `{}' was already applied, not applying again.".format(
overlay_name
)
)
else:
apply_overlay(overlay_name)
if not is_applied(overlay_name):
raise RuntimeError("Failed to apply overlay `{}'".format(overlay_name))
def rm_overlay(overlay_name):
"""
Removes the given overlay. Does not check if the overlay is loaded.
"""
get_logger("DTO").trace("Removing overlay `{}'...".format(overlay_name))
os.rmdir(os.path.join(SYSFS_OVERLAY_BASE_DIR, overlay_name))
def rm_overlay_safe(overlay_name):
"""
Only remove an overlay if it's already applied.
"""
if overlay_name in list(list_overlays(applied_only=True).keys()):
rm_overlay(overlay_name)
else:
get_logger("DTO").debug(
"Overlay `{}' was not loaded, not removing.".format(overlay_name)
)
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