ricardgb opened a new pull request, #19255:
URL: https://github.com/apache/nuttx/pull/19255
> ⚠️ **Disclosure:** developed with **Claude Code** (an AI coding agent) and
validated on real Pico 2 W hardware. Please review accordingly.
## Summary
Adds an on-chip flash **LittleFS** for the RP2350 (rp23xx). A new MTD driver
(`rp23xx_flash_mtd.c`) is created over the region of the QSPI flash that lies
beyond the NuttX image, and the common board bringup mounts a LittleFS on it
for persistent local storage. It uses the RP2350 bootrom flash programming
functions.
Design notes:
- The erase/program routine (`do_flash_op`) runs from RAM (`.ram_code`) with
interrupts disabled and XIP exited during the operation; the QMI window‑1 (CS1)
registers that `flash_exit_xip()` disturbs on the RP2350 are saved/restored.
Erase is chunked **one 4 KiB block per critical section** to bound the
interrupts‑off window.
- Reads go through the **cached XIP window** (`0x10000000`) — the same alias
the CPU executes from; freshness after a program/erase is guaranteed because
`do_flash_op()` calls the bootrom `flash_flush_cache()`.
- Off by default (`CONFIG_RP23XX_FLASH_FILE_SYSTEM`). Region offset/size and
mount point are Kconfig‑configurable.
- A blank/corrupt optional filesystem is **non‑fatal**: it is logged and
bringup continues (previously a failed mount could abort the rest of bringup).
Format once from NSH: `mount -t littlefs -o autoformat /dev/rpflash /data`.
## Impact
- New: `arch/arm/src/rp23xx/rp23xx_flash_mtd.{c,h}`.
- Wiring: arch `Make.defs`/`CMakeLists.txt` (compiled only under
`CONFIG_RP23XX_FLASH_FILE_SYSTEM`), arch `Kconfig` (new options), common
bringup (mount block, guarded). No behaviour change when the option is off (the
default).
## Testing
- **Build:** `raspberrypi-pico-2:nsh` + `CONFIG_RP23XX_FLASH_FILE_SYSTEM=y`
— the driver and bringup compile cleanly; `nxstyle` clean on all changed files.
- **Hardware (Raspberry Pi Pico 2 W):** formatted the FS, wrote/read files,
confirmed **persistence across a power-cycle** (auto-mount of the formatted
FS), and copied a code image onto the LittleFS and **loaded + executed it from
flash**:
```console
nsh> mount -t littlefs -o autoformat /dev/rpflash /data
nsh> echo hello-littlefs > /data/test.txt
nsh> cat /data/test.txt
hello-littlefs
```
After a reboot, `/data` auto-mounts and the contents persist.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
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