Fix nRF52 flash completion and preserve recoverable ExtraFS

scripts/nrf52_internal_flash_fix.py

@@ -0,0 +1,59 @@
+"""Build-local fix for the nRF52 InternalFS SoftDevice flash wait.
+
+GCC 14/LTO can treat the naked SVC wrapper as not writing through its pointer
+argument. It then folds wait_for_async_flash_op_completion() into an immediate
+success return, allowing LittleFS to read or rewrite a page before the async
+erase/program has completed. Keep the SoftDevice state volatile and add a
+compiler barrier after the SVC call. Do not modify PlatformIO's shared SDK.
+"""
+
+from pathlib import Path
+
+
+OLD_WAIT = """  uint8_t sd_en = 0;
+  (void) sd_softdevice_is_enabled(&sd_en);
+
+  if (sd_en) {
+"""
+FIXED_WAIT = """  volatile uint8_t sd_en = 0;
+  (void) sd_softdevice_is_enabled((uint8_t*) &sd_en);
+  __asm volatile ("" ::: "memory");
+
+  if (sd_en) {
+"""
+
+
+def patched_source(source):
+    source = source.replace("\r\n", "\n")
+    if FIXED_WAIT in source and OLD_WAIT not in source:
+        return source
+    if source.count(OLD_WAIT) != 1:
+        raise RuntimeError(
+            "nRF52 flash fix: unrecognized InternalFS flash driver; review "
+            "the framework update before building (shared SDK not modified)"
+        )
+    return source.replace(OLD_WAIT, FIXED_WAIT)
+
+
+def replace_driver(build_env, node):
+    source = Path(node.srcnode().get_abspath())
+    patched = patched_source(source.read_text(encoding="utf-8"))
+    build_env.AppendUnique(CPPPATH=[str(source.parent)])
+    destination = Path(build_env.subst("$BUILD_DIR")) / "patched-nrf52-flash" / source.name
+    destination.parent.mkdir(parents=True, exist_ok=True)
+    if not destination.exists() or destination.read_text(encoding="utf-8") != patched:
+        destination.write_text(patched, encoding="utf-8")
+    print("nRF52 flash: build-local SoftDevice completion wait fix enabled")
+    return build_env.File(str(destination))
+
+
+def install(build_env):
+    build_env.AddBuildMiddleware(
+        replace_driver,
+        "*InternalFileSytem*src*flash*flash_nrf5x.c",
+    )
+
+
+if "Import" in globals():
+    Import("env")
+    install(env)