util/apcb: Add apcb_v3_edit tool

apcb_v3_edit.py tool edits APCB V3 binaries. Specifically it will inject
up to 16 SPDs into an existing APCB. The APCB must have a magic number
at the top of each SPD slot.

BUG=b:209486191
BRANCH=None
TEST=Inject 4 SPDs into magic APCB, boot guybrush with modified APCB

Change-Id: I9148977c415df41210a3a13a1cd9b3bc1504a480
Signed-off-by: Rob Barnes <robbarnes@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60281
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

1 files changed, 156 insertions, 0 deletions

diff --git a/util/apcb/apcb_v3_edit.py b/util/apcb/apcb_v3_edit.py
new file mode 100755
index 0000000000..9a70bace3e
--- /dev/null
+++ b/util/apcb/apcb_v3_edit.py
@@ -0,0 +1,156 @@
+#!/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()