From 84b3a071af706785fa07c34c1c3da8f9df1224ce Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <andrew@tridgell.net>
Date: Sat, 19 Oct 2024 09:02:18 +0900
Subject: [PATCH] support bootloader update with CAN bootloader

---
 Makefile                       |  7 +--
 bl_update/ldscript_bl_CAN.ld   |  2 +
 bl_update/main.c               | 32 ++++++++++++-
 bl_update/set_app_signature.py | 85 ++++++++++++++++++++++++++++++++++
 4 files changed, 122 insertions(+), 4 deletions(-)
 create mode 100755 bl_update/set_app_signature.py

diff --git a/Makefile b/Makefile
index 964087a6..038f6c10 100644
--- a/Makefile
+++ b/Makefile
@@ -174,7 +174,7 @@ $(ELF_FILE): $$(SRC_$(MCU)_BL) $$(SRC_BL) $$(SRC_DRONECAN)
 $(H_FILE): $(BIN_FILE)
 	$$(QUIET)python3 bl_update/make_binheader.py $(BIN_FILE) $(H_FILE)
 
-$(BLU_ELF_FILE): CFLAGS_BLU := $$(MCU_$(MCU)) $$(CFLAGS_$(MCU)) $$(CFLAGS_BASE) -DBOOTLOADER -DUSE_$(PIN) $(EXTRA_CFLAGS) -Wno-unused-variable -Wno-unused-function
+$(BLU_ELF_FILE): CFLAGS_BLU := -DAM32_MCU=\"$(MCU)\" $$(MCU_$(MCU)) $$(CFLAGS_$(MCU)) $$(CFLAGS_BASE) -DBOOTLOADER -DUSE_$(PIN) $(EXTRA_CFLAGS) -Wno-unused-variable -Wno-unused-function
 $(BLU_ELF_FILE): LDFLAGS_BLU := $$(LDFLAGS_COMMON) $$(LDFLAGS_$(MCU)) -T$(xBLU_LDSCRIPT)
 $(BLU_ELF_FILE): $$(SRC_$(MCU)_BL) $$(SRC_BLU) $(H_FILE)
 	$$(QUIET)echo building bootloader updater for $(BUILD) with pin $(PIN)
@@ -191,12 +191,13 @@ $(HEX_FILE): $$(ELF_FILE)
 $(BIN_FILE): $$(HEX_FILE)
 
 # Generate bin and hex files for bl updater
-$(BLU_HEX_FILE): $$(BLU_ELF_FILE)
+$(BLU_BIN_FILE): $$(BLU_ELF_FILE)
 	$$(QUIET)echo Generating $(notdir $$@)
 	$$(QUIET)$(xOBJCOPY) -O binary $$(<) $$(@:.hex=.bin)
+	$$(QUIET)python3 bl_update/set_app_signature.py $$@ $$(<)
 	$$(QUIET)$(xOBJCOPY) $$(<) -O ihex $$(@:.bin=.hex)
 
-$(BLU_AMJ_FILE): $$(BLU_HEX_FILE)
+$(BLU_AMJ_FILE): $$(BLU_BIN_FILE)
 	$$(QUIET)echo Generating $(notdir $$@)
 	$$(QUIET)python3 bl_update/make_amj.py --type bl_update --githash $(shell git rev-parse HEAD) $(BLU_HEX_FILE) $(BLU_AMJ_FILE)
 
diff --git a/bl_update/ldscript_bl_CAN.ld b/bl_update/ldscript_bl_CAN.ld
index fd66569c..84c216fc 100644
--- a/bl_update/ldscript_bl_CAN.ld
+++ b/bl_update/ldscript_bl_CAN.ld
@@ -25,6 +25,8 @@ SECTIONS
     . = ALIGN(4);
     KEEP(*(.isr_vector)) /* Startup code */
     . = ALIGN(4);
+    KEEP(*(.app_signature))
+    . = ALIGN(4);
   } >FLASH
 
   /* The program code and other data goes into FLASH */
diff --git a/bl_update/main.c b/bl_update/main.c
index d34889ad..c4e398bd 100644
--- a/bl_update/main.c
+++ b/bl_update/main.c
@@ -20,10 +20,40 @@
 // dummy pin and port so we can re-use blutil.h
 static GPIO_PORT_TYPE input_port;
 static uint32_t input_pin;
-#define FIRMWARE_RELATIVE_START 0x1000
 
 #define MCU_FLASH_START 0x08000000
 
+
+#if !DRONECAN_SUPPORT
+#define FIRMWARE_RELATIVE_START 0x1000
+#else
+
+#define FIRMWARE_RELATIVE_START 0x4000
+
+#define APP_SIGNATURE_MAGIC1 0x68f058e6
+#define APP_SIGNATURE_MAGIC2 0xafcee5a0
+
+/*
+  application signature, filled in by set_app_signature.py
+ */
+const struct {
+    uint32_t magic1;
+    uint32_t magic2;
+    uint32_t fwlen; // total fw length in bytes
+    uint32_t crc1; // crc32 up to start of app_signature
+    uint32_t crc2; // crc32 from end of app_signature to end of fw
+    char mcu[16];
+    uint32_t unused[2];
+} app_signature __attribute__((section(".app_signature"))) = {
+        .magic1 = APP_SIGNATURE_MAGIC1,
+        .magic2 = APP_SIGNATURE_MAGIC2,
+        .fwlen = 0,
+        .crc1 = 0,
+        .crc2 = 0,
+        .mcu = AM32_MCU,
+};
+#endif
+
 /*
   use stringize to construct an include of the right bootloader header
  */
diff --git a/bl_update/set_app_signature.py b/bl_update/set_app_signature.py
new file mode 100755
index 00000000..aa52d2f5
--- /dev/null
+++ b/bl_update/set_app_signature.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python3
+'''
+set application signature in bin and elf files
+'''
+
+import struct
+import sys
+
+APP_SIGNATURE_MAGIC1 = 0x68f058e6
+APP_SIGNATURE_MAGIC2 = 0xafcee5a0
+
+def crc32(buf):
+    '''crc32 implementation'''
+    crc = 0
+    size = len(buf)
+    for i in range(size):
+        byte = buf[i]
+        crc ^= byte
+        for _ in range(8):
+            mask = -(crc & 1)
+            crc >>= 1
+            crc ^= (0xEDB88320 & mask)
+    return crc
+
+# Example usage:
+# buf = bytearray([0x31, 0x32, 0x33, 0x34])  # Sample input
+# result = crc32(buf, len(buf))
+# print(f"CRC32: {hex(result)}")
+
+def set_app_descriptor(bin_file, elf_file):
+    '''setup app descriptor in bin file and elf file'''
+    descriptor = struct.pack("<II", APP_SIGNATURE_MAGIC1, APP_SIGNATURE_MAGIC2);
+    img = open(bin_file, 'rb').read()
+    len1 = len(img)
+    offset = img.find(descriptor)
+    if offset == -1:
+        print("No APP_DESCRIPTOR found in %s" % bin_file)
+        sys.exit(1)
+
+    # full descriptor length
+    desc_len = 44
+
+    img1 = bytearray(img[:offset])
+    img2 = bytearray(img[offset+desc_len:])
+    crc1 = crc32(img1)
+    crc2 = crc32(img2)
+
+    desc = struct.pack('<III', len(img), crc1, crc2)
+    img = img[:offset+len(descriptor)] + desc + img[offset+len(descriptor)+len(desc):]
+    if len(img) != len1:
+        print("Bad app descriptor size", len1, len(img))
+        sys.exit(1)
+    open(bin_file, 'wb').write(img)
+
+    elf_img = open(elf_file,'rb').read()
+    elf_ofs = elf_img.find(descriptor)
+    if elf_ofs == -1:
+        print("No APP_DESCRIPTOR found in elf file")
+        sys.exit(1)
+    elf_ofs += len(descriptor)
+    elf_img = elf_img[:elf_ofs] + desc + elf_img[elf_ofs+len(desc):]
+    open(elf_file, 'wb').write(elf_img)
+    print("Applied APP_DESCRIPTOR %08x%08x for %s" % (crc1, crc2, bin_file))
+
+from argparse import ArgumentParser
+parser = ArgumentParser(description="AM32 set application signature")
+
+parser.add_argument("binfile", type=str, help="application bin file")
+parser.add_argument("elffile", type=str, help="application elf file")
+
+args = parser.parse_args()
+
+# only apply to CAN firmwares for now
+if args.binfile.find("_CAN_") == -1:
+    sys.exit(0)
+
+if not args.binfile.endswith(".bin"):
+    print("Invalid bin file %s" % args.binfile)
+    sys.exit(1)
+
+if not args.elffile.endswith(".elf"):
+    print("Invalid elf file %s" % args.elffile)
+    sys.exit(1)
+    
+set_app_descriptor(args.binfile, args.elffile)