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fdt: Add Python bindings
An early version of this is available upstream. Bring it in as a starting point. This is from dtc upstream commit e56f2b0. Future work will plumb it into dtoc and remove the now-unnecessary local libraries. Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
parent
46bac66b20
commit
cf2064d785
2 changed files with 512 additions and 0 deletions
389
lib/libfdt/pylibfdt/libfdt.i
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389
lib/libfdt/pylibfdt/libfdt.i
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/*
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* pylibfdt - Flat Device Tree manipulation in Python
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* Copyright (C) 2017 Google, Inc.
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* Written by Simon Glass <sjg@chromium.org>
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*
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* SPDX-License-Identifier: GPL-2.0+ BSD-2-Clause
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*/
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%module libfdt
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%{
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#define SWIG_FILE_WITH_INIT
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#include "libfdt.h"
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%}
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%pythoncode %{
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import struct
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# Error codes, corresponding to FDT_ERR_... in libfdt.h
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(NOTFOUND,
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EXISTS,
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NOSPACE,
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BADOFFSET,
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BADPATH,
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BADPHANDLE,
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BADSTATE,
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TRUNCATED,
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BADMAGIC,
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BADVERSION,
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BADSTRUCTURE,
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BADLAYOUT,
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INTERNAL,
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BADNCELLS,
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BADVALUE,
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BADOVERLAY,
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NOPHANDLES) = QUIET_ALL = range(1, 18)
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# QUIET_ALL can be passed as the 'quiet' parameter to avoid exceptions
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# altogether. All # functions passed this value will return an error instead
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# of raising an exception.
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# Pass this as the 'quiet' parameter to return -ENOTFOUND on NOTFOUND errors,
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# instead of raising an exception.
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QUIET_NOTFOUND = (NOTFOUND,)
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class FdtException(Exception):
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"""An exception caused by an error such as one of the codes above"""
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def __init__(self, err):
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self.err = err
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def __str__(self):
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return 'pylibfdt error %d: %s' % (self.err, fdt_strerror(self.err))
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def strerror(fdt_err):
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"""Get the string for an error number
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Args:
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fdt_err: Error number (-ve)
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Returns:
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String containing the associated error
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"""
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return fdt_strerror(fdt_err)
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def check_err(val, quiet=()):
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"""Raise an error if the return value is -ve
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This is used to check for errors returned by libfdt C functions.
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Args:
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val: Return value from a libfdt function
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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val if val >= 0
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Raises
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FdtException if val < 0
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"""
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if val < 0:
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if -val not in quiet:
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raise FdtException(val)
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return val
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def check_err_null(val, quiet=()):
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"""Raise an error if the return value is NULL
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This is used to check for a NULL return value from certain libfdt C
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functions
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Args:
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val: Return value from a libfdt function
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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val if val is a list, None if not
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Raises
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FdtException if val indicates an error was reported and the error
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is not in @quiet.
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"""
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# Normally a list is returned which contains the data and its length.
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# If we get just an integer error code, it means the function failed.
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if not isinstance(val, list):
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if -val not in quiet:
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raise FdtException(val)
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return val
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class Fdt:
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"""Device tree class, supporting all operations
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The Fdt object is created is created from a device tree binary file,
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e.g. with something like:
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fdt = Fdt(open("filename.dtb").read())
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Operations can then be performed using the methods in this class. Each
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method xxx(args...) corresponds to a libfdt function fdt_xxx(fdt, args...).
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All methods raise an FdtException if an error occurs. To avoid this
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behaviour a 'quiet' parameter is provided for some functions. This
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defaults to empty, but you can pass a list of errors that you expect.
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If one of these errors occurs, the function will return an error number
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(e.g. -NOTFOUND).
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"""
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def __init__(self, data):
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self._fdt = bytearray(data)
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check_err(fdt_check_header(self._fdt));
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def path_offset(self, path, quiet=()):
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"""Get the offset for a given path
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Args:
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path: Path to the required node, e.g. '/node@3/subnode@1'
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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Node offset
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Raises
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FdtException if the path is not valid or not found
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"""
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return check_err(fdt_path_offset(self._fdt, path), quiet)
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def first_property_offset(self, nodeoffset, quiet=()):
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"""Get the offset of the first property in a node offset
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Args:
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nodeoffset: Offset to the node to check
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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Offset of the first property
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Raises
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FdtException if the associated node has no properties, or some
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other error occurred
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"""
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return check_err(fdt_first_property_offset(self._fdt, nodeoffset),
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quiet)
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def next_property_offset(self, prop_offset, quiet=()):
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"""Get the next property in a node
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Args:
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prop_offset: Offset of the previous property
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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Offset of the next property
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Raises:
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FdtException if the associated node has no more properties, or
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some other error occurred
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"""
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return check_err(fdt_next_property_offset(self._fdt, prop_offset),
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quiet)
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def get_name(self, nodeoffset):
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"""Get the name of a node
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Args:
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nodeoffset: Offset of node to check
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Returns:
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Node name
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Raises:
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FdtException on error (e.g. nodeoffset is invalid)
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"""
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return check_err_null(fdt_get_name(self._fdt, nodeoffset))[0]
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def get_property_by_offset(self, prop_offset, quiet=()):
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"""Obtains a property that can be examined
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Args:
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prop_offset: Offset of property (e.g. from first_property_offset())
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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Property object, or None if not found
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Raises:
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FdtException on error (e.g. invalid prop_offset or device
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tree format)
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"""
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pdata = check_err_null(
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fdt_get_property_by_offset(self._fdt, prop_offset), quiet)
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if isinstance(pdata, (int)):
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return pdata
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return Property(pdata[0], pdata[1])
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def first_subnode(self, nodeoffset, quiet=()):
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"""Find the first subnode of a parent node
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Args:
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nodeoffset: Node offset of parent node
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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The offset of the first subnode, if any
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Raises:
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FdtException if no subnode found or other error occurs
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"""
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return check_err(fdt_first_subnode(self._fdt, nodeoffset), quiet)
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def next_subnode(self, nodeoffset, quiet=()):
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"""Find the next subnode
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Args:
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nodeoffset: Node offset of previous subnode
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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The offset of the next subnode, if any
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Raises:
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FdtException if no more subnode found or other error occurs
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"""
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return check_err(fdt_next_subnode(self._fdt, nodeoffset), quiet)
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def totalsize(self):
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"""Return the total size of the device tree
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Returns:
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Total tree size in bytes
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"""
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return check_err(fdt_totalsize(self._fdt))
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def off_dt_struct(self):
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"""Return the start of the device tree struct area
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Returns:
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Start offset of struct area
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"""
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return check_err(fdt_off_dt_struct(self._fdt))
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def pack(self, quiet=()):
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"""Pack the device tree to remove unused space
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This adjusts the tree in place.
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Args:
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quiet: Errors to ignore (empty to raise on all errors)
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Raises:
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FdtException if any error occurs
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"""
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return check_err(fdt_pack(self._fdt), quiet)
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def delprop(self, nodeoffset, prop_name):
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"""Delete a property from a node
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Args:
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nodeoffset: Node offset containing property to delete
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prop_name: Name of property to delete
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Raises:
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FdtError if the property does not exist, or another error occurs
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"""
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return check_err(fdt_delprop(self._fdt, nodeoffset, prop_name))
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def getprop(self, nodeoffset, prop_name, quiet=()):
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"""Get a property from a node
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Args:
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nodeoffset: Node offset containing property to get
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prop_name: Name of property to get
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quiet: Errors to ignore (empty to raise on all errors)
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Returns:
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Value of property as a bytearray, or -ve error number
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Raises:
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FdtError if any error occurs (e.g. the property is not found)
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"""
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pdata = check_err_null(fdt_getprop(self._fdt, nodeoffset, prop_name),
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quiet)
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if isinstance(pdata, (int)):
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return pdata
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return bytearray(pdata[0])
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class Property:
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"""Holds a device tree property name and value.
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This holds a copy of a property taken from the device tree. It does not
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reference the device tree, so if anything changes in the device tree,
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a Property object will remain valid.
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Properties:
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name: Property name
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value: Proper value as a bytearray
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"""
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def __init__(self, name, value):
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self.name = name
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self.value = value
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%}
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%rename(fdt_property) fdt_property_func;
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typedef int fdt32_t;
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%include "libfdt/fdt.h"
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%include "typemaps.i"
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/* Most functions don't change the device tree, so use a const void * */
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%typemap(in) (const void *)(const void *fdt) {
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if (!PyByteArray_Check($input)) {
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SWIG_exception_fail(SWIG_TypeError, "in method '" "$symname"
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"', argument " "$argnum"" of type '" "$type""'");
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}
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$1 = (void *)PyByteArray_AsString($input);
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fdt = $1;
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fdt = fdt; /* avoid unused variable warning */
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}
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/* Some functions do change the device tree, so use void * */
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%typemap(in) (void *)(const void *fdt) {
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if (!PyByteArray_Check($input)) {
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SWIG_exception_fail(SWIG_TypeError, "in method '" "$symname"
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"', argument " "$argnum"" of type '" "$type""'");
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}
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$1 = PyByteArray_AsString($input);
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fdt = $1;
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fdt = fdt; /* avoid unused variable warning */
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}
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%typemap(out) (struct fdt_property *) {
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PyObject *buff;
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if ($1) {
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resultobj = PyString_FromString(
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fdt_string(fdt1, fdt32_to_cpu($1->nameoff)));
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buff = PyByteArray_FromStringAndSize(
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(const char *)($1 + 1), fdt32_to_cpu($1->len));
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resultobj = SWIG_Python_AppendOutput(resultobj, buff);
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}
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}
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%apply int *OUTPUT { int *lenp };
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/* typemap used for fdt_getprop() */
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%typemap(out) (const void *) {
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if (!$1)
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$result = Py_None;
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else
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$result = Py_BuildValue("s#", $1, *arg4);
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}
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/* We have both struct fdt_property and a function fdt_property() */
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%warnfilter(302) fdt_property;
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/* These are macros in the header so have to be redefined here */
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int fdt_magic(const void *fdt);
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int fdt_totalsize(const void *fdt);
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int fdt_off_dt_struct(const void *fdt);
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int fdt_off_dt_strings(const void *fdt);
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int fdt_off_mem_rsvmap(const void *fdt);
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int fdt_version(const void *fdt);
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int fdt_last_comp_version(const void *fdt);
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int fdt_boot_cpuid_phys(const void *fdt);
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int fdt_size_dt_strings(const void *fdt);
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int fdt_size_dt_struct(const void *fdt);
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%include <../libfdt/libfdt.h>
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123
lib/libfdt/pylibfdt/setup.py
Executable file
123
lib/libfdt/pylibfdt/setup.py
Executable file
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#!/usr/bin/env python
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"""
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setup.py file for SWIG libfdt
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Copyright (C) 2017 Google, Inc.
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Written by Simon Glass <sjg@chromium.org>
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SPDX-License-Identifier: GPL-2.0+ BSD-2-Clause
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Files to be built into the extension are provided in SOURCES
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C flags to use are provided in CPPFLAGS
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Object file directory is provided in OBJDIR
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Version is provided in VERSION
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If these variables are not given they are parsed from the Makefiles. This
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allows this script to be run stand-alone, e.g.:
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./pylibfdt/setup.py install [--prefix=...]
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"""
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from distutils.core import setup, Extension
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import os
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import re
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import sys
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# Decodes a Makefile assignment line into key and value (and plus for +=)
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RE_KEY_VALUE = re.compile('(?P<key>\w+) *(?P<plus>[+])?= *(?P<value>.*)$')
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def ParseMakefile(fname):
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"""Parse a Makefile to obtain its variables.
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This collects variable assigments of the form:
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VAR = value
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VAR += more
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It does not pick out := assignments, as these are not needed here. It does
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handle line continuation.
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Returns a dict:
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key: Variable name (e.g. 'VAR')
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value: Variable value (e.g. 'value more')
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"""
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makevars = {}
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with open(fname) as fd:
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prev_text = '' # Continuation text from previous line(s)
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for line in fd.read().splitlines():
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if line and line[-1] == '\\': # Deal with line continuation
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prev_text += line[:-1]
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continue
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elif prev_text:
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line = prev_text + line
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prev_text = '' # Continuation is now used up
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m = RE_KEY_VALUE.match(line)
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if m:
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value = m.group('value') or ''
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key = m.group('key')
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# Appending to a variable inserts a space beforehand
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if 'plus' in m.groupdict() and key in makevars:
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makevars[key] += ' ' + value
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else:
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makevars[key] = value
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return makevars
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def GetEnvFromMakefiles():
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"""Scan the Makefiles to obtain the settings we need.
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|
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This assumes that this script is being run from the top-level directory,
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not the pylibfdt directory.
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Returns:
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Tuple with:
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List of swig options
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Version string
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List of files to build
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List of extra C preprocessor flags needed
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Object directory to use (always '')
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"""
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basedir = os.path.dirname(os.path.dirname(os.path.abspath(sys.argv[0])))
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swig_opts = ['-I%s' % basedir]
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makevars = ParseMakefile(os.path.join(basedir, 'Makefile'))
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version = '%s.%s.%s' % (makevars['VERSION'], makevars['PATCHLEVEL'],
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makevars['SUBLEVEL'])
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makevars = ParseMakefile(os.path.join(basedir, 'libfdt', 'Makefile.libfdt'))
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files = makevars['LIBFDT_SRCS'].split()
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files = [os.path.join(basedir, 'libfdt', fname) for fname in files]
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files.append('pylibfdt/libfdt.i')
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cflags = ['-I%s' % basedir, '-I%s/libfdt' % basedir]
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objdir = ''
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return swig_opts, version, files, cflags, objdir
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progname = sys.argv[0]
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files = os.environ.get('SOURCES', '').split()
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cflags = os.environ.get('CPPFLAGS', '').split()
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objdir = os.environ.get('OBJDIR')
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version = os.environ.get('VERSION')
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swig_opts = []
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# If we were called directly rather than through our Makefile (which is often
|
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# the case with Python module installation), read the settings from the
|
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# Makefile.
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if not all((version, files, cflags, objdir)):
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swig_opts, version, files, cflags, objdir = GetEnvFromMakefiles()
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libfdt_module = Extension(
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'_libfdt',
|
||||
sources = files,
|
||||
extra_compile_args = cflags,
|
||||
swig_opts = swig_opts,
|
||||
)
|
||||
|
||||
setup(
|
||||
name='libfdt',
|
||||
version= version,
|
||||
author='Simon Glass <sjg@chromium.org>',
|
||||
description='Python binding for libfdt',
|
||||
ext_modules=[libfdt_module],
|
||||
package_dir={'': objdir},
|
||||
py_modules=['pylibfdt/libfdt'],
|
||||
)
|
Loading…
Add table
Reference in a new issue