Contribution description

After two failed attempts, I finally managed to get a shared and unified setup working for the RP2350. As opposed to the other approaches I took, where I tried to fully unify both the RISCV and ARM versions, this version takes a different approach similar to cortexm_common or riscv_common where each CPU still exists as a separate entity, e.g. rp2350_arm and rp2350_riscv but uses the shared rp2350_common folder.

This PR supersedes both #21745 and #21746, as in it:

• adds support for the Hazard3 CPU used on the RP2350
• adds support for the XH3IRQ Interrupt Controller used by the Hazard3. While fairly similar to CLIC/PLIC, the Hazard3 on the RP2350 actually has a custom interrupt controller to "mimick" the way interrupts work on the Cortex ARM side, even having support for direct vector table jumps (Not enabled here since I wanted to still use the trap_entry/trap_handler of riscv_common.
• updates the uart
• enables interrupts on the CortexM33
• unifies both the RISCV and ARM side of the RP2350
• renames rp2350 (arm version) to rp2350_arm
• renames rpi-pico-2 (arm version) to rpi-pico-2-arm
• fixes debugging completely (GDB now runs smoothly both on ARM and RISCV)

However, as of now, it does not yet add the multicore example. All the points raised in the other PRs also still hold true.

Testing procedure

Remember to specify USEMODULE += stdio_uart if you wish to print via UART.

For my testing I mostly modified examples/basic/blinky to also print. On RISCV you can also use xh3irq_force_irq to force interrupts for testing purposes, for example, on each blinky loop, if you feel like it :)

RISCV

make PROGRAMMER=openocd QUIET=0 BOARD=rpi-pico-2-riscv flash flashes the pico 2 in RISCV mode using openocd, you can also use make PROGRAMMER=picotool QUIET=0 BOARD=rpi-pico-2-riscv flash to flash it using picotool.

ARM

make PROGRAMMER=openocd QUIET=0 BOARD=rpi-pico-2-arm flash flashes the pico 2 in RISCV mode using openocd, you can also use make PROGRAMMER=picotool QUIET=0 BOARD=rpi-pico-2-arm flash to flash it using picotool.

Issues/PRs references