51 lines
1.4 KiB
Tcl
51 lines
1.4 KiB
Tcl
# SPDX-License-Identifier: GPL-2.0-or-later
|
|
|
|
# Description:
|
|
# Measure the CPU clock frequency of an ARM Cortex-M based device.
|
|
#
|
|
# Return:
|
|
# The CPU clock frequency in Hz. A negative value indicates that the loop
|
|
# counter was saturated.
|
|
#
|
|
# Note:
|
|
# You may need to adapt the number of cycles for your device.
|
|
#
|
|
add_help_text cortex_m_test_cpu_speed "Measure the CPU clock frequency of an ARM Cortex-M based device"
|
|
add_usage_text cortex_m_test_cpu_speed {address [timeout [cycles_per_loop]]}
|
|
proc cortex_m_test_cpu_speed { address { timeout 200 } { cycles_per_loop 4 } } {
|
|
set loop_counter_start 0xffffffff
|
|
|
|
halt
|
|
|
|
# Backup registers and memory.
|
|
set backup_regs [get_reg -force {pc r0 xpsr}]
|
|
set backup_mem [read_memory $address 16 3]
|
|
|
|
# We place the following code at the given address to measure the
|
|
# CPU clock frequency:
|
|
#
|
|
# 3801: subs r0, #1
|
|
# d1fd: bne #-2
|
|
# e7fe: b #-4
|
|
write_memory $address 16 {0x3801 0xd1fd 0xe7fe}
|
|
|
|
set_reg "pc $address r0 $loop_counter_start"
|
|
resume
|
|
sleep $timeout
|
|
halt
|
|
|
|
# Get the loop counter value from register r0.
|
|
set loop_counter_end [dict values [get_reg r0]]
|
|
set loop_counter_diff [expr {$loop_counter_start - $loop_counter_end}]
|
|
|
|
# Restore registers and memory.
|
|
set_reg $backup_regs
|
|
write_memory $address 16 $backup_mem
|
|
|
|
if { [expr {$loop_counter_end == 0}] } {
|
|
return -1
|
|
}
|
|
|
|
return [expr {double($loop_counter_diff) * $cycles_per_loop / $timeout * 1000}]
|
|
}
|