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# Copyright (C) 2017 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#!/usr/bin/env python
"""Basic utility for reading and writing registers on an ASPEED BMC.
The values hardcoded are for the ASPEED AST2400.
"""
import subprocess
import sys
IO_TOOL = 'devmem'
PROTECTION_KEY = '0x1E6E2000'
HWTRAP = '0x1E6E2070'
# The AST2400 SCU Password (as int for write_register)
SCU_PASSWORD = 0x1688A8A8
# Bits 13:12
SPI_MASK = 0xffffcfff
# Enable SPI Master
SPI_MASTER = 0x1000
# Enable SPI Master and SPI Slave to AHB Bridge
SPI_MASTER_SLAVE = 0x2000
# Enable SPI Pass-through
SPI_BYPASS = 0x3000
def read_register(address):
"""Run a tool to read a register value.
This will convert it to an integer.
"""
output = subprocess.check_output([IO_TOOL, address]).replace('\n', '')
value = int(output, 16)
return value
def write_register(address, value):
"""Run a tool to write the 32-bit register value."""
subprocess.check_output([IO_TOOL, address, '32', '0x%x' % value])
return
def set_master(value):
"""Set Hardware Strapping to SPI Master."""
print 'Setting to "SPI Master"'
masked = value & SPI_MASK
masked |= SPI_MASTER
print 'setting: 0x%x' % masked
write_register(HWTRAP, masked)
def set_ahb_bridge(value):
"""Set hardware strapping to spi master and spi-slave to ahb."""
print 'Setting to "SPI Master and SPI Slave to AHB Bridge"'
masked = value & SPI_MASK
masked |= SPI_MASTER_SLAVE
print 'setting: 0x%x' % masked
write_register(HWTRAP, masked)
def set_bypass(value):
"""Set hardware strappign to spi bypass."""
print 'Setting to "Enable SPI Pass-through"'
masked = value & SPI_MASK
masked |= SPI_BYPASS
print 'setting: 0x%x' % masked
write_register(HWTRAP, masked)
def usage():
"""Print usage string."""
print 'usage: %s master|bridge|bypass' % sys.argv[0]
print 'master sets the BMC SPI to Master.'
print ('bridge sets the BMC SPI to Master-Slave bridge to AHB (for BIOS ' +
'Update).')
print 'bypass sets the BMC SPI to Bypass (default).'
def main():
"""Main entry point for execution."""
if len(sys.argv) != 2:
usage()
sys.exit(-1)
ctrl = sys.argv[1].lower()
if ctrl not in ('master', 'bridge', 'bypass'):
usage()
sys.exit(-1)
locked = False
# Check if locked
value = read_register(PROTECTION_KEY)
if value == 1:
print 'Presently unlocked'
else:
print 'Presently locked'
locked = True
# if Locked we need to unlock it.
if locked:
write_register(PROTECTION_KEY, SCU_PASSWORD)
# Read the value.
value = read_register(HWTRAP)
if value & SPI_BYPASS == SPI_BYPASS:
print 'Presently set to bypass'
elif value & SPI_MASTER == SPI_MASTER:
print 'Presently set to master'
elif value & SPI_MASTER_SLAVE == SPI_MASTER_SLAVE:
print 'Presently set to master-slave'
if ctrl == 'master':
set_master(value)
elif ctrl == 'bridge':
set_ahb_bridge(value)
elif ctrl == 'bypass':
set_bypass(value)
# We leave it unlocked in case it was locked.
# we could lock it.
# TODO(venture): lock it by writing any non-password value.
if __name__ == '__main__':
main()
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