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#!/usr/bin/env python3
# Script for editing APCB_V3 binaries, such as injecting SPDs.
import sys
import re
import argparse
from collections import namedtuple
from struct import *
import binascii
import os
# SPD_MAGIC matches the expected SPD header:
# Byte 0 = 0x23 = 512 bytes total / 384 bytes used
# Byte 1 = 0x11 = Revision 1.1
# Byte 2 = 0x11 = LPDDR4X SDRAM
# Byte 3 = 0x0E = Non-DIMM Solution
SPD_MAGIC = bytes.fromhex('2311110E')
EMPTY_SPD = b'\x00' * 512
spd_ssp_struct_fmt = '??B?IIBBBxIIBBBx'
spd_ssp_struct = namedtuple(
'spd_ssp_struct', 'SpdValid, DimmPresent, \
PageAddress, NvDimmPresent, \
DramManufacturersIDCode, Address, \
SpdMuxPresent, MuxI2CAddress, MuxChannel, \
Technology, Package, SocketNumber, \
ChannelNumber, DimmNumber')
apcb_v3_header_fmt = 'HHHHBBBBBBH'
apcb_v3_header = namedtuple(
'apcb_v3_header', 'GroupId, TypeId, SizeOfType, \
InstanceId, ContextType, ContextFormat, UnitSize, \
PriorityMask, KeySize, KeyPos, BoardMask')
def parseargs():
parser = argparse.ArgumentParser(description='Inject SPDs into APCB binaries')
parser.add_argument(
'apcb_in',
type=str,
help='APCB input file')
parser.add_argument(
'apcb_out',
type=str,
help='APCB output file')
parser.add_argument(
'--spd_sources',
nargs='+',
help='List of SPD sources')
return parser.parse_args()
def chksum(data):
sum = 0
for b in data[:16] + data[17:]:
sum = (sum + b) & 0xff
return (0x100 - sum) & 0xff
def inject(orig, insert, offset):
return b''.join([orig[:offset], insert, orig[offset + len(insert):]])
def main():
args = parseargs()
print(f'Reading input APCB from {args.apcb_in}')
with open(args.apcb_in, 'rb') as f:
apcb = f.read()
orig_apcb_len = len(apcb)
assert chksum(apcb) == apcb[16], f'ERROR: {args.apcb_in} checksum is invalid'
print(f'Using SPD Sources = {args.spd_sources}')
spds = []
for spd_source in args.spd_sources:
with open(spd_source, 'rb') as f:
spd_data = bytes.fromhex(re.sub(r'\s+', '', f.read().decode()))
assert(len(spd_data) == 512), f'ERROR: {spd_source} not 512 bytes'
spds.append(spd_data)
spd_offset = 0
instance = 0
while True:
spd_offset = apcb.find(SPD_MAGIC, spd_offset)
if spd_offset < 0:
print('No more SPD magic numbers in APCB')
break
spd_ssp_offset = spd_offset - calcsize(spd_ssp_struct_fmt)
spd_ssp_bytes = apcb[spd_ssp_offset:spd_offset]
spd_ssp = spd_ssp_struct._make(
unpack(spd_ssp_struct_fmt, spd_ssp_bytes))
assert spd_ssp.DimmNumber >= 0 and spd_ssp.DimmNumber <= 1, \
'ERROR: Unexpected dimm number found in APCB'
assert spd_ssp.ChannelNumber >= 0 and spd_ssp.ChannelNumber <= 1, \
'ERROR: Unexpected channel number found in APCB'
print(f'Found SPD instance {instance} with channel {spd_ssp.ChannelNumber} '
f'and dimm {spd_ssp.DimmNumber} at offset {spd_offset}')
# APCB V3 header is above first channel 0 entry
if spd_ssp.ChannelNumber == 0:
apcb_v3_header_offset = spd_ssp_offset - \
calcsize(apcb_v3_header_fmt) - 4
apcb_v3_header_bytes = apcb[apcb_v3_header_offset:
apcb_v3_header_offset + calcsize(apcb_v3_header_fmt)]
apcb_v3 = apcb_v3_header._make(
unpack(apcb_v3_header_fmt, apcb_v3_header_bytes))
apcb_v3 = apcb_v3._replace(BoardMask=(1 << instance))
if instance < len(spds):
print(f'Enabling channel {spd_ssp.ChannelNumber}, '
f'dimm {spd_ssp.DimmNumber} and injecting SPD')
spd_ssp = spd_ssp._replace(SpdValid=True, DimmPresent=True)
spd = spds[instance]
else:
print(f'Disabling channel {spd_ssp.ChannelNumber}, '
f'dimm {spd_ssp.DimmNumber} and clearing SPD')
spd_ssp = spd_ssp._replace(SpdValid=False, DimmPresent=False)
spd = EMPTY_SPD
assert len(spd) == 512, f'ERROR: Expected SPD to be 512 bytes, got {len(spd)}'
apcb = inject(apcb, pack(spd_ssp_struct_fmt, *spd_ssp), spd_ssp_offset)
apcb = inject(apcb, spd, spd_offset)
if spd_ssp.ChannelNumber == 0:
apcb = inject(apcb, pack(apcb_v3_header_fmt, *apcb_v3), apcb_v3_header_offset)
else:
instance += 1
spd_offset += 512
assert instance >= len(spds), \
f'ERROR: Not enough SPD slots in APCB, found {instance}, need {len(spds)}'
print(f'Fixing checksum and writing to {args.apcb_out}')
apcb = inject(apcb, bytes([chksum(apcb)]), 16)
assert chksum(apcb) == apcb[16], 'ERROR: Final checksum is invalid'
assert orig_apcb_len == len(apcb), \
'ERROR: The size of the APCB binary changed.'
print(f'Writing {len(apcb)} bytes to {args.apcb_out}')
with open(args.apcb_out, 'wb') as f:
f.write(apcb)
if __name__ == "__main__":
main()
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