Add make format target

This simplifies the formatting before creating PR, just 'make format'.

Author: ChinYikMing

Makefile

@@ -488,6 +488,30 @@ quake: artifact $(quake_deps)
 endif
 endif
 
+CLANG_FMT := $(shell which clang-format 2>/dev/null)
+SH_FMT := $(shell which shfmt 2>/dev/null)
+BLACK := $(shell which black 2>/dev/null)
+SUBMODULES := $(shell git config --file .gitmodules --get-regexp path | awk '{ print $$2 }')
+SUBMODULES_PRUNE_PATHS := $(shell for subm in $(SUBMODULES); do echo -n "-path \"./$$subm\" -o "; done | sed 's/ -o $$//')
+format:
+ifeq ($(CLANG_FMT),)
+	$(error clang-format not found. Install clang-format version 18 or above and try again)
+else
+        # Skip formatting submodules and everything in $(OUT), apply the same rule for shfmt and black
+	$(Q)$(shell $(CLANG_FMT) -i $(shell find . \( $(SUBMODULES_PRUNE_PATHS) -o -path \"./$(OUT)\" \) -prune -o -name "*.[ch]" -print))
+endif
+ifeq ($(SH_FMT),)
+	$(error shfmt not found. Install shfmt and try again)
+else
+	$(Q)$(shell $(SH_FMT) -w $(shell find . \( $(SUBMODULES_PRUNE_PATHS) -o -path \"./$(OUT)\" \) -prune -o -name "*.sh" -print))
+endif
+ifeq ($(BLACK),)
+	$(error black not found. Install black version 25.1.0 or above and try again)
+else
+	$(Q)$(shell $(BLACK) --quiet $(shell find . \( $(SUBMODULES_PRUNE_PATHS) -o -path \"./$(OUT)\" \) -prune -o \( -name "*.py" -o -name "*.pyi" \) -print))
+endif
+	$(Q)$(call notice,All files are properly formatted.)
+
 clean:
 	$(VECHO) "Cleaning... "
 	$(Q)$(RM) $(BIN) $(OBJS) $(DEV_OBJS) $(BUILD_DTB) $(BUILD_DTB2C) $(HIST_BIN) $(HIST_OBJS) $(deps) $(WEB_FILES) $(CACHE_OUT)