Python script to read/write physical address (depends on python-mmap)

#!/usr/bin/env python

# -*- coding: utf-8 -*-

# Copyright (C) 2013, Elphel.inc.

# configuration of the DDR-related registers

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 3 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

__author__ = "Andrey Filippov"

__copyright__ = "Copyright 2014, Elphel, Inc."

__license__ = "GPL"

__version__ = "3.0+"

__maintainer__ = "Andrey Filippov"

__email__ = "andrey@elphel.com"

__status__ = "Development"

import mmap

import sys

import struct

PAGE_SIZE=4096

endian="<" # little, ">" for big

if len(sys.argv)<1:

    print "Usage: ", sys.argv[0]+" address [data]"

    exit (0)

addr=int(sys.argv[1],16) & 0xfffffffc

data=0

writeMode=len(sys.argv)>2

if (writeMode):

    data=int(sys.argv[2],16)

with open("/dev/mem", "r+b") as f:

    page_addr=addr & (~(PAGE_SIZE-1))

    page_offs=addr-page_addr

    if (page_addr>=0x80000000):

        page_addr-= (1<<32)

    mm = mmap.mmap(f.fileno(), PAGE_SIZE, offset=page_addr)

    if writeMode:

        packedData=struct.pack(endian+"L",data)

        d=struct.unpack(endian+"L",packedData)[0]

        mm[page_offs:page_offs+4]=packedData

        print ("0x%08x <== 0x%08x (%d)"%(addr,d,d))

    else:

        data=struct.unpack(endian+"L",mm[page_offs:page_offs+4])

        d=data[0]

        print ("0x%08x ==> 0x%08x (%d)"%(addr,d,d))

    mm.close()