Add RP2350 port (Intech Studio Grid RP2350)

.claude/skills/build/scripts/check_build.py

@@ -51,6 +51,7 @@
   'lpc55': ['lpcxpresso55s69'],
   'maxim': ['max32666fthr'],
   'mimxrt10xx': ['imxrt1064_evk', 'imxrt1170_evk'],
+  'rp2350': ['intechstudio_grid_rp2350'],
   'samd51': ['intech_grid'],
   'stm32f3': ['stm32f303disco'],
   'stm32f4': ['stm32f411ve_discovery', 'feather_stm32f405_express'],

.claude/test/test_build.py

@@ -375,8 +375,8 @@ def test_app_nothing_builds_is_uncovered(self):
 
   def test_top_level_app_selects_ports_whose_backend_compiles_it(self):
     ports = {cb.port_of(b) for b, _ in classify('apps/blinky/src/blinky.c')[2]}
-    self.assertEqual(ports, {'espressif', 'lpc55', 'maxim', 'mimxrt10xx', 'samd51', 'stm32f3', 'stm32f4', 'stm32h5',
-                             'stm32h7'})
+    self.assertEqual(ports, {'espressif', 'lpc55', 'maxim', 'mimxrt10xx', 'rp2350', 'samd51', 'stm32f3', 'stm32f4',
+                             'stm32h5', 'stm32h7'})
 
   def test_a_ports_cmake_files_select_its_cmake_build(self):
     for port in ('kinetis_k32l2', 'stm32h7', 'stm32l4'):

.github/workflows/build.yml

@@ -76,6 +76,7 @@ jobs:
           - 'lpc55'
           - 'maxim'
           - 'mimxrt10xx'
+          - 'rp2350'
           - 'samd51'
           - 'stm32f3'
           - 'stm32f4'

README.md

@@ -35,6 +35,7 @@ Not all features are implemented for all MCUs, following is supported MCUs and i
 | LPC55              |  ✔   |      ✔       |             |                  |    ✔     |      |
 | MAX32              |  ✔   |      ✔       |      ✔      |                  |          |      |
 | iMXRT              |  ✔   |      ✔       |      ✔      |                  |    ✔     |      |
+| RP2350             |  ✔   |      ✔       |      ✔      |                  |    ✔     |      |
 | SAMD51             |  ✔   |              |      ✔      |        ✔         |    ✔     |      |
 | STM32F3            |  ✔   |      ✔       |      ✔      |        ✔         |    ✔     |      |
 | STM32F4            |  ✔   |      ✔       |      ✔      |        ✔         |    ✔     |      |

ports/family_support.cmake

@@ -126,7 +126,7 @@ function(family_add_app NAME SOURCE_DIR)
     -DARTIFACT_PATH=${ARTIFACT_PATH}
     -DPython_EXECUTABLE=${Python_EXECUTABLE}
     )
-  foreach (VAR LOG LOGGER CFLAGS_CLI TRACE_ETM LTO_ON)
+  foreach (VAR LOG LOGGER CFLAGS_CLI TRACE_ETM LTO_ON PICO_SDK_PATH PICO_PLATFORM LD_FLASH_BOOT_SIZE)
     if (DEFINED ${VAR})
       # LIST_SEPARATOR below turns | back into ; so a list value stays one argument
       string(REPLACE ";" "|" VALUE "${${VAR}}")

ports/rp2350/CMakeLists.txt

@@ -0,0 +1,51 @@
+cmake_minimum_required(VERSION 3.20)
+
+# family.cmake (included by family_support.cmake) pulls in pico_sdk_init.cmake, which must happen before project()
+include(${CMAKE_CURRENT_LIST_DIR}/../family_support.cmake)
+
+project(tinyuf2 C CXX ASM)
+set(CMAKE_EXECUTABLE_SUFFIX .elf)
+
+# pico-sdk's toolchain file does not set CMAKE_SIZE, which family_configure_common runs after the build
+if (NOT CMAKE_SIZE)
+  string(REGEX REPLACE "gcc$" "size" CMAKE_SIZE "${CMAKE_C_COMPILER}")
+endif ()
+
+pico_sdk_init()
+
+#------------------------------------
+# TinyUF2
+#------------------------------------
+add_executable(tinyuf2
+  board_flash.c
+  boards.c
+  ${TOP}/lib/tinyusb/src/portable/raspberrypi/rp2040/dcd_rp2040.c
+  ${TOP}/lib/tinyusb/src/portable/raspberrypi/rp2040/rp2040_usb.c
+  )
+
+# the WS2812 PIO program
+pico_generate_pio_header(tinyuf2 ${CMAKE_CURRENT_LIST_DIR}/ws2812.pio)
+
+# The bootloader links into the first LD_FLASH_BOOT_SIZE bytes of flash only. pico_override_flash_size() cannot be used
+# for that: it also defines PICO_FLASH_SIZE_BYTES, which makes flash_range_erase/program hard_assert() on every offset
+# beyond the bootloader, i.e. on every application write. So only the linker region is overridden.
+set(PICO_FLASH_SIZE_BYTES_STRING "${LD_FLASH_BOOT_SIZE}")
+configure_file(${PICO_SDK_PATH}/src/rp2_common/pico_standard_link/pico_flash_region.template.ld
+  ${CMAKE_CURRENT_BINARY_DIR}/tinyuf2/pico_flash_region.ld)
+pico_add_linker_script_override_path(tinyuf2 ${CMAKE_CURRENT_BINARY_DIR}/tinyuf2 FILES pico_flash_region.ld)
+
+# drop the SDK runtime parts the bootloader does not use (default alarm pool, printf, float/double, panic, ...)
+pico_minimize_runtime(tinyuf2)
+
+# see __wrap_irq_add_shared_handler() in boards.c
+target_link_options(tinyuf2 PUBLIC "LINKER:--wrap=irq_add_shared_handler")
+
+# the RP2040 and RP2350 share one TinyUSB device driver (OPT_MCU_RP2040)
+family_configure_tinyuf2(tinyuf2 OPT_MCU_RP2040)
+family_gen_uf2(tinyuf2 ${UF2_FAMILY_ID})
+
+#------------------------------------
+# Application
+#------------------------------------
+family_add_app(blinky ${TOP}/apps/blinky)
+family_add_app(update-tinyuf2 ${TOP}/apps/self_update SELF_UPDATE)

ports/rp2350/README.md

@@ -0,0 +1,88 @@
+# TinyUF2 for RP2350
+
+Port for the RP2350 (Arm Cortex-M33, secure) built on [pico-sdk](https://github.com/raspberrypi/pico-sdk). The bootloader runs
+behind the RP2350 bootrom, which finds its `IMAGE_DEF` in flash and starts it: the bootrom USB bootloader (BOOTSEL) stays
+available as recovery whatever is in flash.
+
+Boards:
+
+| Board | Notes |
+| --- | --- |
+| `intechstudio_grid_rp2350` | 16 WS2812 on GPIO6 (PIO0), volume `GRIDRP2350` |
+| `intechstudio_wrid_rp2350` | Same hardware and USB IDs as `intechstudio_grid_rp2350`, volume `WRIDRP2350`, to tell the two bootloaders apart |
+
+## Build
+
+pico-sdk is not a submodule: `tools/get_deps.py` fetches the pinned version into `lib/mcu/raspberrypi/pico-sdk`.
+
+```
+python3 tools/get_deps.py rp2350
+cmake -B build -G Ninja -DBOARD=intechstudio_grid_rp2350 ports/rp2350
+cmake --build build
+```
+
+Use another pico-sdk with `-DPICO_SDK_PATH=<path>` or the `PICO_SDK_PATH` environment variable. The build also needs a host
+compiler, for the SDK's `pioasm`.
+
+## Flash layout
+
+| Address | Content |
+| --- | --- |
+| `0x10000000` | TinyUF2, 32 KB region (`LD_FLASH_BOOT_SIZE` in `board.cmake`) |
+| `0x10008000` | Application |
+
+The application must be linked at `0x10008000`, which `app.cmake` does for the applications built here. A UF2 file of an
+application uses the family ID `0xe48bff59` (`RP2350_ARM_S`) and absolute flash addresses. To create one from a `.bin`:
+
+```
+uf2conv.py -c -b 0x10008000 -f 0xe48bff59 firmware.bin
+```
+
+The bootloader refuses UF2 blocks below the application start or past the end of the flash, and erases a 4 KB sector only
+when a block to write does not fit in blank flash, writing back the blocks of that sector it knows to be good.
+
+The bootloader image is about 17 KB, so the region could shrink: 16 KB was not reached with pico-sdk, TinyUSB's mass storage
+class and the flash driver. What was tried: `pico_minimize_runtime()` and replacing `irq_add_shared_handler()` (both used,
+about 3.4 KB saved) and LTO (does not link with the Arm GNU 13.3 and Debian 14.2 toolchains).
+
+## Flashing the bootloader
+
+Hold BOOTSEL while plugging in, then copy `_bin/<board>/tinyuf2.uf2` to the BOOTSEL drive. Updating a running bootloader is done with
+the self-update below. SWD flash targets are not set up.
+
+## Entering the bootloader
+
+- Double tap reset: the LEDs show purple for 0.5 s after reset, a second reset within that time stays in the bootloader.
+- The bootloader also stays when the application is missing or invalid: the stack pointer in the first vector must point into
+  SRAM and the reset vector must be a Thumb address inside the application area.
+- From an application: `board_reboot_to_bootloader()`.
+
+The double tap uses the `DOUBLE_TAP` flag of POWMAN, armed from the start of the bootloader until it starts the application or
+enters DFU mode. A RUN pin reset powers down RAM and also resets the POWMAN scratch registers, which are only kept over watchdog
+and software resets: the application request therefore uses `powman_hw->scratch[0]`, the reset button the flag.
+
+## Self-update
+
+`update-tinyuf2.uf2` is built next to the bootloader in `_bin/<board>/apps`. Copy it to the bootloader drive: it runs from the
+application area, rewrites the bootloader and erases itself, then the new bootloader starts. The application area is
+overwritten, so copy the application again afterwards.
+
+The bootloader's first sector holds the `IMAGE_DEF` the bootrom looks for. The update erases it first and writes it last, so an
+interrupted update leaves no bootable mix of old and new code: the bootrom then starts its USB bootloader, from where
+`tinyuf2.uf2` can be copied again. An image is only written when its vector table is valid, it fits the boot area and holds an
+`IMAGE_DEF` start marker in its first 4 KB.
+
+## Not implemented
+
+- Write protection: `board_flash_protect_bootloader()` does nothing. UF2 writes cannot reach the bootloader, but the flash
+  itself is not protected against an application. It needs the block protect bits of the flash chip, whose type is not known yet.
+- `BOARD_FLASH_SIZE` in `board.cmake` is the assumed 2 MB, to be confirmed for the board.
+- Applications for the RISC-V cores and the non-secure Arm family are not supported.
+
+## Notes
+
+- pico-sdk's own TinyUSB support is switched off in `family.cmake`: its glue defines functions with the names of this repo's
+  `family_support.cmake` and replaces them. TinyUF2 builds `lib/tinyusb`, and CMake prints a warning that SDK USB support is unavailable.
+- `pico_override_flash_size()` must not be used for the boot region: it also defines `PICO_FLASH_SIZE_BYTES`, and the SDK's
+  `flash_range_erase()`/`flash_range_program()` assert on every offset beyond it.
+- Flash writes keep interrupts off, as the flash leaves XIP mode meanwhile.

ports/rp2350/app.cmake

@@ -0,0 +1,20 @@
+include_guard(GLOBAL)
+
+# applications are standalone pico-sdk projects: pico_sdk_init() must come after their project() and before their targets
+enable_language(CXX)
+if (NOT CMAKE_SIZE)
+  string(REGEX REPLACE "gcc$" "size" CMAKE_SIZE "${CMAKE_C_COMPILER}")
+endif ()
+pico_sdk_init()
+
+function(family_configure_app TARGET)
+  family_configure_common(${TARGET})
+
+  # boards.c is compiled into the application too, it drives the WS2812
+  pico_generate_pio_header(${TARGET} ${FAMILY_PATH}/ws2812.pio)
+
+  # link behind the bootloader: the flash region starts at the application start
+  configure_file(${FAMILY_PATH}/linker/pico_flash_region_app.template.ld
+    ${CMAKE_CURRENT_BINARY_DIR}/${TARGET}/pico_flash_region.ld @ONLY)
+  pico_add_linker_script_override_path(${TARGET} ${CMAKE_CURRENT_BINARY_DIR}/${TARGET} FILES pico_flash_region.ld)
+endfunction()