nmaggioni opened a new pull request, #16841:
URL: https://github.com/apache/nuttx/pull/16841
## Summary
Both cores of this uC can have a custom SWD DAP instance ID set. Changing
these from the default values is uncommon but can help with multi-drop
debugging where more than one board is daisy-chained to the same debug probe.
Currently, this can be achieved with a custom OpenOCD config like in the
following example, but such a technique needs more testing before it can be
considered stable for a broader use.
<details>
<summary>rp2040-custom_instid.cfg</summary>
```plaintext
# SPDX-License-Identifier: GPL-2.0-or-later
# RP2040 is a microcontroller with dual Cortex-M0+ core.
# https://www.raspberrypi.com/documentation/microcontrollers/rp2040.html
# The device requires multidrop SWD for debug.
transport select swd
source [find target/swj-dp.tcl]
if { [info exists CHIPNAME] } {
set _CHIPNAME $CHIPNAME
} else {
set _CHIPNAME rp2040
}
if { [info exists WORKAREASIZE] } {
set _WORKAREASIZE $WORKAREASIZE
} else {
set _WORKAREASIZE 0x10000
}
if { [info exists CPUTAPID] } {
set _CPUTAPID $CPUTAPID
} else {
set _CPUTAPID 0x01002927
}
if { [info exists DAP_INSTID_0] } {
set _DAP_INSTID_0 $DAP_INSTID_0
} else {
set _DAP_INSTID_0 0
}
if { [info exists DAP_INSTID_1] } {
set _DAP_INSTID_1 $DAP_INSTID_1
} else {
set _DAP_INSTID_1 1
}
# Set to '1' to start rescue mode
if { [info exists RESCUE] } {
set _RESCUE $RESCUE
} else {
set _RESCUE 0
}
# Set to '0' or '1' for single core configuration, 'SMP' for -rtos hwthread
# handling of both cores, anything else for isolated debugging of both cores
if { [info exists USE_CORE] } {
set _USE_CORE $USE_CORE
} else {
set _USE_CORE SMP
}
set _BOTH_CORES [expr { $_USE_CORE != 0 && $_USE_CORE != 1 }]
swj_newdap $_CHIPNAME cpu -expected-id $_CPUTAPID
# The rescue debug port uses the DP CTRL/STAT bit DBGPWRUPREQ to reset the
# PSM (power on state machine) of the RP2040 with a flag set in the
# VREG_AND_POR_CHIP_RESET register. Once the reset is released
# (by clearing the DBGPWRUPREQ flag), the bootrom will run, see this flag,
# and halt. Allowing the user to load some fresh code, rather than loading
# the potentially broken code stored in flash
if { $_RESCUE } {
dap create $_CHIPNAME.rescue_dap -chain-position $_CHIPNAME.cpu -dp-id
$_CPUTAPID -instance-id 0xf -ignore-syspwrupack
init
# Clear DBGPWRUPREQ
$_CHIPNAME.rescue_dap dpreg 0x4 0x00000000
# Verifying CTRL/STAT is 0
set _CTRLSTAT [$_CHIPNAME.rescue_dap dpreg 0x4]
if {[expr {$_CTRLSTAT & 0xf0000000}]} {
echo "Rescue failed, DP CTRL/STAT readback $_CTRLSTAT"
} else {
echo "Now restart OpenOCD without RESCUE flag and load code to
RP2040"
}
shutdown
}
# core 0
if { $_USE_CORE != 1 } {
dap create $_CHIPNAME.dap0 -chain-position $_CHIPNAME.cpu -dp-id
$_CPUTAPID -instance-id $_DAP_INSTID_0
set _TARGETNAME_0 $_CHIPNAME.core0
target create $_TARGETNAME_0 cortex_m -dap $_CHIPNAME.dap0 -coreid 0
# srst does not exist; use SYSRESETREQ to perform a soft reset
$_TARGETNAME_0 cortex_m reset_config sysresetreq
}
# core 1
if { $_USE_CORE != 0 } {
dap create $_CHIPNAME.dap1 -chain-position $_CHIPNAME.cpu -dp-id
$_CPUTAPID -instance-id $_DAP_INSTID_1
set _TARGETNAME_1 $_CHIPNAME.core1
target create $_TARGETNAME_1 cortex_m -dap $_CHIPNAME.dap1 -coreid 1
$_TARGETNAME_1 cortex_m reset_config sysresetreq
}
if {[string compare $_USE_CORE SMP] == 0} {
$_TARGETNAME_0 configure -rtos nuttx
$_TARGETNAME_1 configure -rtos nuttx
target smp $_TARGETNAME_0 $_TARGETNAME_1
}
if { $_USE_CORE == 1 } {
set _FLASH_TARGET $_TARGETNAME_1
} else {
set _FLASH_TARGET $_TARGETNAME_0
}
# Backup the work area. The flash probe runs an algorithm on the target CPU.
# The flash is probed during gdb connect if gdb_memory_map is enabled (by
default).
$_FLASH_TARGET configure -work-area-phys 0x20010000 -work-area-size
$_WORKAREASIZE -work-area-backup 1
set _FLASHNAME $_CHIPNAME.flash
flash bank $_FLASHNAME rp2040_flash 0x10000000 0 0 0 $_FLASH_TARGET
if { $_BOTH_CORES } {
# Alias to ensure gdb connecting to core 1 gets the correct memory map
flash bank $_CHIPNAME.alias virtual 0x10000000 0 0 0 $_TARGETNAME_1
$_FLASHNAME
# Select core 0
targets $_TARGETNAME_0
}
```
</details>
<details>
<summary>openocd.cfg</summary>
```plaintext
source [find interface/cmsis-dap.cfg]
adapter driver picoprobe
transport select swd
adapter speed 5000
set DAP_INSTID_0 4
set DAP_INSTID_1 5
source [find rp2040-custom_instid.cfg]
```
</details>
## Impact
Users will be able to debug boards with non-standard SWD DAP IDs.
## Testing
These changes were tested on a Linux host, targeting a custom Cortex-M0+
(RP2040) board using NuttX v12.8.0 as the baseline. They were then manually
ported to the current master branch.
The OpenOCD version used in the tests was 0.12.0+dev-gcf9c0b4.
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