#! /usr/bin/python

import struct
import sys
import getopt
from os import *
from mmap import *

def usage():
   	''' This is the Usage Method '''

   	print '\t\t pcisysfs.py  --get --offset <offset> --res <resource>'
   	print '\t\t pcisysfs.py --set --val <val>  --offset <offset> --res <resource>'
        sys.exit(1)

def pci_mem_read(mm,offset):
    mm.seek(offset)
    read_data_stream=mm.read(4)
    print ""
    reg_val=struct.unpack('I',read_data_stream)
    print "reg_val read:%x"%reg_val
    return reg_val

def pci_mem_write(mm,offset,data):
    mm.seek(offset)
    #print "data to write:%x"%data
    mm.write(struct.pack('I',data))

def pci_set_value(resource,val,offset):
    fd=open(resource,O_RDWR)
    mm=mmap(fd,0)
    pci_mem_write(mm,offset,val)
    close(fd)

def pci_get_value(resource,offset):
    fd=open(resource,O_RDWR)
    mm=mmap(fd,0)
    pci_mem_read(mm,offset)
    close(fd)

def main(argv):

    ''' The main function will read the user input from the
    command line argument and  process the request  '''

    opts = ''
    val = ''
    choice = ''
    resource = ''
    offset = ''

    try:
        opts, args = getopt.getopt(argv, "hgsv:" , \
        ["val=","res=","offset=","help", "get", "set"])
	
    except getopt.GetoptError:
        usage()

    for opt,arg in opts:

        if opt in ('-h','--help'):
            choice = 'help'

        elif opt in ('-g', '--get'):
            choice = 'get'

        elif opt in ('-s', '--set'):
            choice = 'set'

        elif opt ==  '--res':
            resource = arg

        elif opt ==  '--val':
            val = int(arg,16)

        elif opt ==  '--offset':
            offset = int(arg,16)

    if choice == 'set' and val != '' and offset !='' and resource !='':
        pci_set_value(resource,val,offset)

    elif choice == 'get' and offset != '' and resource !='':
        pci_get_value(resource,offset)

    else:
        usage()

#Calling the main method
if __name__ == "__main__":
	main(sys.argv[1:])