76 lines
2.4 KiB
INI
76 lines
2.4 KiB
INI
# SPDX-License-Identifier: GPL-2.0-or-later
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# Config for Raspberry Pi used as a bitbang adapter.
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# https://www.raspberrypi.com/documentation/computers/raspberry-pi.html
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# Supports all models with 40-pin or 26-pin GPIO connector up to Raspberry Pi 4 B
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# also supports Raspberry Pi Zero, Zero W and Zero 2 W.
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# Adapter speed calibration is computed from cpufreq/scaling_max_freq.
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# Adjusts automatically if CPU is overclocked.
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adapter driver bcm2835gpio
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proc read_file { name } {
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if {[catch {open $name r} fd]} {
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return ""
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}
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set result [read $fd]
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close $fd
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return $result
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}
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proc measure_clock {} {
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set result [exec vcgencmd measure_clock arm]
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set clock_hz [lindex [split $result "="] 1]
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expr { $clock_hz / 1000 }
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}
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proc get_max_cpu_clock { default } {
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set clock [read_file /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq]
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if { $clock > 100000 } {
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return $clock
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}
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# cpufreq not available. As the last resort try Broadcom's proprietary utility
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if {![catch measure_clock clock] && $clock > 100000} {
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return $clock
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}
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echo "Warn : Host CPU clock unknown."
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echo "Warn : Using the highest possible value $default kHz as a safe default."
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echo "Warn : Expect JTAG/SWD clock significantly slower than requested."
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return $default
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}
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set compat [read_file /proc/device-tree/compatible]
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set clocks_per_timing_loop 4
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if {[string match *bcm2711* $compat]} {
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set speed_offset 52
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} elseif {[string match *bcm2837* $compat] || [string match *bcm2710* $compat]} {
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set speed_offset 34
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} elseif {[string match *bcm2836* $compat] || [string match *bcm2709* $compat]} {
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set speed_offset 36
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} elseif {[string match *bcm2835* $compat] || [string match *bcm2708* $compat]} {
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set clocks_per_timing_loop 6
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set speed_offset 32
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} elseif {[string match *bcm2712* $compat]} {
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echo "Error: Raspberrypi Pi 5 has moved GPIOs to PCIe connected RP1 chip."
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echo "Error: Native GPIO handling is not supported, use 'raspberrypi5-gpiod.cfg'"
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shutdown
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} else {
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set speed_offset 32
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echo "Warn : Unknown type of the host SoC. Expect JTAG/SWD clock slower than requested."
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}
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set clock [get_max_cpu_clock 2000000]
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set speed_coeff [expr { $clock / $clocks_per_timing_loop }]
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# Transition delay calculation: SPEED_COEFF/khz - SPEED_OFFSET
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# The coefficients depend on system clock and CPU frequency scaling.
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bcm2835gpio speed_coeffs $speed_coeff $speed_offset
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source [find interface/raspberrypi-gpio-connector.cfg]
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