mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-29 08:01:08 +00:00
ec564b47da
This Python library provides a way to access the contents of the device tree. It uses fdtget, so is inefficient for larger device tree files. Signed-off-by: Simon Glass <sjg@chromium.org>
86 lines
2.1 KiB
Python
86 lines
2.1 KiB
Python
#!/usr/bin/python
|
|
#
|
|
# Copyright (C) 2016 Google, Inc
|
|
# Written by Simon Glass <sjg@chromium.org>
|
|
#
|
|
# SPDX-License-Identifier: GPL-2.0+
|
|
#
|
|
|
|
import struct
|
|
|
|
# A list of types we support
|
|
(TYPE_BYTE, TYPE_INT, TYPE_STRING, TYPE_BOOL) = range(4)
|
|
|
|
def BytesToValue(bytes):
|
|
"""Converts a string of bytes into a type and value
|
|
|
|
Args:
|
|
A string containing bytes
|
|
|
|
Return:
|
|
A tuple:
|
|
Type of data
|
|
Data, either a single element or a list of elements. Each element
|
|
is one of:
|
|
TYPE_STRING: string value from the property
|
|
TYPE_INT: a byte-swapped integer stored as a 4-byte string
|
|
TYPE_BYTE: a byte stored as a single-byte string
|
|
"""
|
|
size = len(bytes)
|
|
strings = bytes.split('\0')
|
|
is_string = True
|
|
count = len(strings) - 1
|
|
if count > 0 and not strings[-1]:
|
|
for string in strings[:-1]:
|
|
if not string:
|
|
is_string = False
|
|
break
|
|
for ch in string:
|
|
if ch < ' ' or ch > '~':
|
|
is_string = False
|
|
break
|
|
else:
|
|
is_string = False
|
|
if is_string:
|
|
if count == 1:
|
|
return TYPE_STRING, strings[0]
|
|
else:
|
|
return TYPE_STRING, strings[:-1]
|
|
if size % 4:
|
|
if size == 1:
|
|
return TYPE_BYTE, bytes[0]
|
|
else:
|
|
return TYPE_BYTE, list(bytes)
|
|
val = []
|
|
for i in range(0, size, 4):
|
|
val.append(bytes[i:i + 4])
|
|
if size == 4:
|
|
return TYPE_INT, val[0]
|
|
else:
|
|
return TYPE_INT, val
|
|
|
|
def GetEmpty(type):
|
|
"""Get an empty / zero value of the given type
|
|
|
|
Returns:
|
|
A single value of the given type
|
|
"""
|
|
if type == TYPE_BYTE:
|
|
return chr(0)
|
|
elif type == TYPE_INT:
|
|
return struct.pack('<I', 0);
|
|
elif type == TYPE_STRING:
|
|
return ''
|
|
else:
|
|
return True
|
|
|
|
def fdt32_to_cpu(val):
|
|
"""Convert a device tree cell to an integer
|
|
|
|
Args:
|
|
Value to convert (4-character string representing the cell value)
|
|
|
|
Return:
|
|
A native-endian integer value
|
|
"""
|
|
return struct.unpack(">I", val)[0]
|