* Use polled waiting on platforms that support it
Due to context switching overhead waiting a very short amount of time on
a sleeping thread is often not accurate and in fact not usable for timing
critical usage i.e. in a driver. Thus we use polled waiting for ranges
in the us range on platforms that support it instead. The fallback is
the thread sleeping mechanism.
This includes:
* ARM platforms with CYCCNT register (ARMv7, ARMv8) this is
incremented at CPU clock frequency
* GD32VF103 RISC-V port with CSR_MCYCLE register this is incremented at
CPU clock frequency
* RP2040 ARMv6 port which uses the integrated timer peripheral which is
incremented with a fixed 1MHz frequency
* Use wait_us() instead of chSysPolledDelayX
...as it is powered by busy waiting now.
* Add chibios waiting methods test bench
* Tentative Teensy 3.5 support
* Set firmware format to .hex for ARM Teensys
* Got to "device descriptor failed" by comparing with Teensy 3.6 code
* Drop down to 96MHz...
* Bump back up to 120MHz
* Disable RESET keycode because of naming conflicts
* Add Pico SDK as submodule
* Add RP2040 build support to QMK
* Adjust USB endpoint structs for RP2040
* Add RP2040 bootloader and double-tap reset routine
* Add generic and pro micro RP2040 boards
* Add RP2040 onekey keyboard
* Add WS2812 PIO DMA enabled driver and documentation
Supports regular and open-drain output configuration. RP2040 GPIOs are
sadly not 5V tolerant, so this is a bit use-less or needs extra hardware
or you take the risk to fry your hardware.
* Adjust SIO Driver for RP2040
* Adjust I2C Driver for RP2040
* Adjust SPI Driver for RP2040
* Add PIO serial driver and documentation
* Add general RP2040 documentation
* Apply suggestions from code review
Co-authored-by: Nick Brassel <nick@tzarc.org>
Co-authored-by: Nick Brassel <nick@tzarc.org>
