[Core] Add Raspberry Pi RP2040 support

[KarlK90]

Building on the great work of @hanya, @xyzz and @tzarc this PR adds support for RP2040 to QMK.

Todo

QMK:

• General code style
• Documentation updates
• QMK moves to ChibiOS 21.11.x or Trunk builds
• Rebase onto develop
• Double Tap reset to jump to bootloader
• Sort out USB driver hacks for correct HID enumeration [RP2040] Init USB out endpoints on transfer start ChibiOS/ChibiOS-Contrib#316
• SIO Split Keyboard Driver (This needs patches to ChibiOS)
• I2C Driver
• SPI Driver
• PIO Half-duplex split comms
• PIO WS2812 driver

Chibi OS:

• Apply SIO and RP2040 Patches (Part of 21.11.2 and Trunk)
• later Initialization of RAM areas in crt1.c has to be done in assembly. (If using the memcpy/memset functions from rp2040 bootrom)
• later Add *.preinit_array sections to xtors in order to call the VTABLE population for the functions in rp2040 bootrom
• later Port USB bootup fixes from pico-sdk to USB Driver (Only affects B0 and B1 Revisions of the RP2040 chips)

Future work after this PR

• RP2040 optimized Math function compiler intrinsics support
• EEPROM emulation for via(l) support
• WS2812 PIO driver uses DMA (actually done in this PR)
• PWM Audio output, this needs a ChibiOS driver
• PWM LED output, this needs a ChibiOS driver
• ADC support, this needs a ChibiOS driver

Description

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

• [Feature Request] Support for Raspberry Pi Pico #11649

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[zykrah]

Hi, i was just wondering if work is still being done on this?

[tzarc]

Hi, i was just wondering if work is still being done on this?

Can't move until ChibiOS/ChibiOS-Contrib#307 is sorted.

[zykrah]

Hi, i was just wondering if work is still being done on this?

Can't move until ChibiOS/ChibiOS-Contrib#307 is sorted.

I have a fork of chibios contrib 21.6.x that succesfully builds. Though you will have to see how i did it, as i didnt actually update the other MCUs to 21.11.x, rather it uses the master branch of chibios just for building the rp2040 and the other stuff still builds using chibios 20.3.x. (This was the only way i could get it to build properly without making major changes)

[zykrah]

This is the fork for reference: https://github.com/zykrahgaming/ChibiOS-Contrib

[zykrah]

ChibiOS/ChibiOS-Contrib#310
I have made a PR which has updated ChibiOS-Contrib to the ChibiOS master branch (21.11.x)

[KarlK90]

@zykrahgaming Thanks for your interest and effort in pushing RP2040 support forward 💪 I hope that contrib resurrects from the winter sleep soonish. To support split keebs I started #15907 which brings split comms support for the RP2040.

[hanya]

Double tap reset to enter bootloader have to be called after platform_setup() function in main() function.
Because ChibiOS initialize clocks for USB in chSysInit() function called in platform_setup function.
The following code supports double tap reset.
https://gist.github.com/hanya/57eb9703361a38d40bad6b05340ccc91
The boot_double_reset_bootloader function does not work if called in board_init() function.
So if we have entry point between platform_setup and protocol_setup functions, put it there.

[KarlK90]

@hanya thank you for the bootloader code and all the previous work on the contrib code. I'll have a more in depth look next week.

Giovanni the maintainer of ChibiOS also voiced interest to move the rp2040 contrib drivers into mainline, but wants somebody to actively maintain them. This might be interesting for you?

[stefancrain]

Good news! ChibiOS/ChibiOS-Contrib#310 (comment)

[KarlK90]

For people that wondered why their build failed with error messages when including an rp2040.h file to their keyboard folder. This is due to a naming conflict with another header file from CMSIS with the same name. To mitigate the issue do not include a file with the name rp2040.h in your keyboard folder.