Initial Longer3D LK1/2 (Alfawise U20/U20+/U30) support (#14597)

buildroot/share/PlatformIO/ldscripts/alfawise_Ux0.ld

@@ -0,0 +1,14 @@
+MEMORY
+{
+  ram (rwx) : ORIGIN = 0x20000000, LENGTH = 64K - 40
+  rom (rx)  : ORIGIN = 0x08010000, LENGTH = 512K - 64K
+}
+
+/* Provide memory region aliases for common.inc */
+REGION_ALIAS("REGION_TEXT", rom);
+REGION_ALIAS("REGION_DATA", ram);
+REGION_ALIAS("REGION_BSS", ram);
+REGION_ALIAS("REGION_RODATA", rom);
+
+/* Let common.inc handle the real work. */
+INCLUDE common.inc

buildroot/share/PlatformIO/scripts/alfawise_Ux0.py

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+Import("env")
+
+# Relocate firmware from 0x08000000 to 0x08010000
+for define in env['CPPDEFINES']:
+    if define[0] == "VECT_TAB_ADDR":
+        env['CPPDEFINES'].remove(define)
+env['CPPDEFINES'].append(("VECT_TAB_ADDR", "0x08010000"))
+env.Replace(LDSCRIPT_PATH="buildroot/share/PlatformIO/ldscripts/alfawise_Ux0.ld")
+
+# Encrypt ${PROGNAME}.bin and save it as 'project.bin'
+def encrypt(source, target, env):
+    import os
+
+    firmware = open(target[0].path, "rb")
+    marlin_alfa = open(target[0].dir.path +'/project.bin', "wb")
+    length = os.path.getsize(target[0].path)
+    position = 0
+    try:
+        while position < length:
+            byte = firmware.read(1)
+            marlin_alfa.write(byte)
+            position += 1
+    finally:
+        firmware.close()
+        marlin_alfa.close()
+env.AddPostAction("$BUILD_DIR/${PROGNAME}.bin", encrypt);

buildroot/share/tests/alfawise_U20-tests

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+#!/usr/bin/env bash
+#
+# Build tests for STM32F103VET6
+#
+
+# exit on first failure
+set -e
+
+use_example_configs Alfawise/U20
+opt_set MOTHERBOARD BOARD_LONGER3D_LK
+opt_set SERIAL_PORT 1
+exec_test $1 $2 "Full-featured U20 config"
+
+# cleanup
+restore_configs