[Core] Add Raspberry Pi RP2040 support (#14877)

* 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>

1 files changed, 57 insertions, 0 deletions

diff --git a/platforms/chibios/bootloaders/rp2040.c b/platforms/chibios/bootloaders/rp2040.c
new file mode 100644
index 0000000000..13a54036ef
--- /dev/null
+++ b/platforms/chibios/bootloaders/rp2040.c
@@ -0,0 +1,57 @@
+// Copyright 2022 Stefan Kerkmann
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "quantum.h"
+#include "hal.h"
+#include "bootloader.h"
+#include "pico/bootrom.h"
+
+#if !defined(RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED)
+#    define RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED_MASK 0U
+#else
+#    define RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED_MASK (1U << RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED)
+#endif
+
+__attribute__((weak)) void mcu_reset(void) {
+    NVIC_SystemReset();
+}
+void bootloader_jump(void) {
+    reset_usb_boot(RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED_MASK, 0U);
+}
+
+void enter_bootloader_mode_if_requested(void) {}
+
+#if defined(RP2040_BOOTLOADER_DOUBLE_TAP_RESET)
+#    if !defined(RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT)
+#        define RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT 200U
+#    endif
+
+// Needs to be located in a RAM section that is never initialized on boot to
+// preserve its value on reset
+static volatile uint32_t __attribute__((section(".ram0.bootloader_magic"))) magic_location;
+const uint32_t magic_token = 0xCAFEB0BA;
+
+// We can not use the __early_init / enter_bootloader_mode_if_requested hook as
+// we depend on an already initialized system with usable memory regions and
+// populated function pointer tables to the optimized math functions in the
+// bootrom. This function is called just prior to main.
+void __late_init(void) {
+    // All clocks have to be enabled before jumping to the bootloader function,
+    // otherwise the bootrom will be stuck infinitely.
+    clocks_init();
+
+    if (magic_location != magic_token) {
+        magic_location = magic_token;
+        // ChibiOS is not initialized at this point, so sleeping is only
+        // possible via busy waiting. The internal timer peripheral is running
+        // at this point with a precision of 1us.
+        chSysPolledDelayX(MS2RTC(1 * MHZ, RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT));
+        magic_location = 0;
+        return;
+    }
+
+    magic_location = 0;
+    reset_usb_boot(RP2040_BOOTLOADER_DOUBLE_TAP_RESET_LED_MASK, 0U);
+}
+
+#endif