mimxrt: Make linker scripts configurable.

Can simply add LD_FILES to a board's mpconfigboard.mk
to change the linkerscripts, such as to change the section
sizes, or change the contents for each region. Example usage:

LD_FILES = $(BOARD_DIR)/my_board.ld boards/common.ld

Signed-off-by: Dryw Wade <dryw.wade@sparkfun.com>

Author: sfe-SparkFro

ports/mimxrt/Makefile

@@ -56,7 +56,7 @@ MCUX_SDK_DIR = lib/nxp_driver/sdk
 MCU_DIR = $(MCUX_SDK_DIR)/devices/$(MCU_SERIES)
 
 # Select linker scripts based on MCU_SERIES
-LD_FILES = boards/$(MCU_SERIES).ld boards/common.ld
+LD_FILES ?= boards/$(MCU_SERIES).ld boards/common.ld
 
 # Parameter configurations for generation
 AF_FILE = boards/$(MCU_SERIES)_af.csv
@@ -573,7 +573,7 @@ $(HEADER_BUILD)/qstrdefs.generated.h: $(BOARD_DIR)/mpconfigboard.h
 $(GEN_FLEXRAM_CONFIG_SRC): $(HEADER_BUILD)
 	$(ECHO) "Create $@"
 	$(Q)$(PYTHON) $(MAKE_FLEXRAM_LD) -d $(TOP)/$(MCU_DIR)/$(MCU_SERIES)$(MCU_CORE).h \
-		-f $(TOP)/$(MCU_DIR)/$(MCU_SERIES)$(MCU_CORE)_features.h -l boards/$(MCU_SERIES).ld -c $(MCU_SERIES) > $@
+		-f $(TOP)/$(MCU_DIR)/$(MCU_SERIES)$(MCU_CORE)_features.h $(addprefix -l,$(LD_FILES)) -c $(MCU_SERIES) > $@
 
 # Use a pattern rule here so that make will only call make-pins.py once to make
 # both pins_gen.c and pins.h

ports/mimxrt/boards/make-flexram-config.py

@@ -55,9 +55,14 @@
 
 
 # Value parser
-def mimxrt_default_parser(defines_file, features_file, ld_script):
-    with open(ld_script, "r") as input_file:
-        input_str = input_file.read()
+def mimxrt_default_parser(defines_file, features_file, ld_scripts):
+    input_str = ""
+    if ld_scripts is None:
+        # Default linker script
+        ld_scripts = ["boards/MIMXRT1021.ld"]
+    for ld_script in ld_scripts:
+        with open(ld_script, "r") as input_file:
+            input_str += input_file.read()
     #
     ocram_match = re.search(ocram_regex, input_str, re.MULTILINE)
     dtcm_match = re.search(dtcm_regex, input_str, re.MULTILINE)
@@ -249,7 +254,9 @@ def main(defines_file, features_file, ld_script, controller):
         "--ld_file",
         dest="linker_file",
         help="Path to the aggregated linker-script",
-        default="MIMXRT1021.ld",
+        action="append",
+        # Can't specify default here when using 'append' action, see
+        # https://github.com/python/cpython/issues/60603
     )
     parser.add_argument(
         "-c", "--controller", dest="controller", help="Controller name", default="MIMXRT1021"