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#!/usr/bin/env bash
# SPDX-License-Identifier: BSD-3-Clause
ROM="$1"
declare -i NEW_SPEED="$2"
readonly EFS_SIG_DWORD="55aa55aa"
readonly FAST_SPEED_NEW_F15_MOD_60_6F_OFFSET=0x41
readonly SPI_FASTSPEED_F17_MOD_00_2F_OFFSET=0x44
readonly SPI_FASTSPEED_F17_MOD_30_3F_OFFSET=0x48
# print out the very simple usage
usage() {
echo "Usage: $0 <ROM> <Speed>"
echo " Speed must be between 0 & 5"
echo " 0: 66.66Mhz"
echo " 1: 33.33MHz"
echo " 2: 22.22MHz"
echo " 3: 16.66MHz"
echo " 4: 100MHz"
echo " 5: 800KHz"
}
# Validate the input parameters
if [[ $# -ne 2 || ! -f "${ROM}" || "${NEW_SPEED}" -lt 0 || "${NEW_SPEED}" -gt 5 ]]; then
usage
exit 1
fi
# Read a 32, 16, or 8 bit value from a location in a binary file
getval() {
local location=$1
local length=$2
if [[ ${length} -eq 1 ]]; then
dd "if=${ROM}" bs=1 "skip=${location}" "count=${length}" 2>/dev/null | hexdump -v -e '1/1 "%02x\n"'
elif [[ ${length} -eq 2 ]]; then
dd "if=${ROM}" bs=1 "skip=${location}" "count=${length}" 2>/dev/null | hexdump -v -e '1/2 "%04x\n"'
elif [[ ${length} -eq 4 ]]; then
dd "if=${ROM}" bs=1 "skip=${location}" "count=${length}" 2>/dev/null | hexdump -v -e '1/4 "%08x\n"'
else
echo "Error: invalid value"
exit 1
fi
}
# Update a location in a binary
# Note that the passed in value must be formatted correctly:
# Each byte needs to be specified as "\\xXX" where X is a hex digit
setval() {
local location=$1
local length=$2
local hexval=$3
# shellcheck disable=SC2059
if ! printf "$hexval" | dd "of=${ROM}" bs=1 "seek=${location}" "count=${length}" conv=notrunc status=none; then
echo "Error: Could not write to ${ROM}"
exit 1
fi
}
# Print the speed associated with the passed-in value
showspeed() {
local speedval=$1
case ${speedval} in
0 | 00) echo "0: 66.66Mhz" ;;
1 | 01) echo "1: 33.33MHz" ;;
2 | 02) echo "2: 22.22MHz" ;;
3 | 03) echo "3: 16.66MHz" ;;
4 | 04) echo "4: 100MHz" ;;
5 | 05) echo "5: 800KHz" ;;
ff) echo "Error: Speed not set" ;;
*) echo "Error: Unknown speed (${speedval})" ;;
esac
}
# Locate the SPI speed data and update it to the new speed
update_efs() {
local location=$1
local updated_speed=0
for speed_offset in FAST_SPEED_NEW_F15_MOD_60_6F_OFFSET SPI_FASTSPEED_F17_MOD_00_2F_OFFSET SPI_FASTSPEED_F17_MOD_30_3F_OFFSET; do
local speed_val
local speed_loc=$((location + speed_offset))
speed_val=$(getval "${speed_loc}" "1")
if [[ "${speed_val}" != "ff" ]]; then
printf "Found speed value of %s at %#06x\n" "$(showspeed "${speed_val}")" "${speed_loc}"
updated_speed=1
setval "${speed_loc}" "1" "\\x0${NEW_SPEED}"
speed_val=$(getval "${speed_loc}" "1")
printf "New speed value: %s\n" "$(showspeed "${speed_val}")"
fi
done
if [[ ${updated_speed} -eq 0 ]]; then
echo "Error: Could not find speed value to update."
exit 1
fi
}
# Find the EFS location and update the speed
main() {
local location
local val
for i in {0..5}; do
location="$((0xffffff - (0x80000 << i) + 0x20000 + 1))"
val="$(getval "${location}" 4 )"
if [[ "${val}" == "${EFS_SIG_DWORD}" ]]; then
printf "EFS found at %#06x\n" "${location}"
update_efs "${location}"
exit 0
fi
done
echo "Error: EFS not found in ${ROM}."
exit 1
}
main
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