[realtek-ambz2] Implement OTA

Author: prokoma

builder/family/realtek-ambz2.py

@@ -3,6 +3,7 @@
 from os.path import isfile, join
 from shutil import copyfile
 
+from ltchiptool.soc.ambz2.util.models.config import ImageConfig
 from platformio.platform.base import PlatformBase
 from platformio.platform.board import PlatformBoardConfig
 from SCons.Script import DefaultEnvironment, Environment
@@ -15,6 +16,22 @@
 
 COMPONENT_DIR = join("$SDK_DIR", "component")
 
+
+# Get image decryption public key
+def get_public_key(private: bytes) -> bytes:
+    from ltchiptool.util.curve25519 import X25519PrivateKey
+
+    key = X25519PrivateKey.from_private_bytes(private)
+    return key.public_key()
+
+
+def encode_for_define(data: bytes) -> str:
+    # we need to escape both shell and the C string
+    return '\\"' + "".join(f"\\\\x{byte:02x}" for byte in data) + '\\"'
+
+
+public_key_bytes = get_public_key(ImageConfig(**board.get("image")).keys.decryption)
+
 # Flags
 queue.AppendPublic(
     CCFLAGS=[
@@ -39,6 +56,7 @@
         ("__ARM_ARCH_8M_MAIN__", "1"),
         ("CONFIG_BUILD_RAM", "1"),
         "V8M_STKOVF",
+        ("IMAGE_PUBLIC_KEY", encode_for_define(public_key_bytes)),
     ],
     CPPPATH=[
         # allow including <ctype.h> from GCC instead of RTL SDK
@@ -419,17 +437,20 @@
 image_part_table = "${BUILD_DIR}/image_part_table.${FLASH_PART_TABLE_OFFSET}.bin"
 image_bootloader = "${BUILD_DIR}/image_bootloader.${FLASH_BOOT_OFFSET}.bin"
 image_firmware_is = "${BUILD_DIR}/image_firmware_is.${FLASH_OTA1_OFFSET}.bin"
+image_firmware_is_ota = "${BUILD_DIR}/image_firmware_is_ota.${FLASH_OTA1_OFFSET}.bin"
 env.Replace(
     # linker command (dual .bin outputs)
     LINK='${LTCHIPTOOL} link2bin ${BOARD_JSON} "" ""',
     # UF2OTA input list
     UF2OTA=[
-        # same OTA images for flasher and device
-        f"{image_firmware_is},{image_firmware_is}=device:ota1,ota2;flasher:ota1,ota2",
+        # use unmodified image for flasher
+        f"{image_firmware_is},{image_firmware_is}=flasher:ota1,ota2",
+        # use patched OTA image for device
+        f"{image_firmware_is_ota},{image_firmware_is_ota}=device:ota1,ota2",
         # having flashed an application image, update the bootloader and partition table (incl. keys)
         f"{image_bootloader},{image_bootloader}=flasher:boot,boot",
         f"{image_part_table},{image_part_table}=flasher:part_table,part_table",
         # clearing headers of the "other" OTA image (hence the indexes are swapped)
-        f"{image_ota_clear},{image_ota_clear}=device:ota2,ota1;flasher:ota2,ota1",
+        f"{image_ota_clear},{image_ota_clear}=flasher:ota2,ota1",
     ],
 )

cores/realtek-ambz2/base/api/lt_ota.c

@@ -2,23 +2,130 @@
 
 #include <libretiny.h>
 #include <sdk_private.h>
+#include <osdep_service.h>
+#include <device_lock.h>
+
+// from SDK
+extern uint32_t sys_update_ota_get_curr_fw_idx(void);
+
+#define FLASH_SECTOR_SIZE		0x1000
+// IMAGE_PUBLIC_KEY is defined by the build script
+#define IMAGE_PUBLIC_KEY_OFFSET 32
+#define IMAGE_PUBLIC_KEY_LENGTH 32
+
+typedef enum {
+	INVALID	 = 0,
+	DISABLED = 1,
+	ENABLED	 = 2,
+} lt_ota_image_state_t;
+
+static bool lt_ota_get_image_offset(uint8_t index, uint32_t *offset) {
+	switch (index) {
+		case 1:
+			*offset = FLASH_OTA1_OFFSET;
+			break;
+		case 2:
+			*offset = FLASH_OTA2_OFFSET;
+			break;
+		default:
+			return false;
+	}
+	return true;
+}
+
+static uint8_t lt_ota_get_other_index(uint8_t index) {
+	return index ^ 0b11; // 1 -> 2, 2 -> 1
+}
+
+static lt_ota_image_state_t lt_ota_get_image_state(uint8_t index) {
+	uint32_t offset;
+	if (!lt_ota_get_image_offset(index, &offset))
+		return INVALID;
+
+	uint8_t public_key[IMAGE_PUBLIC_KEY_LENGTH];
+	uint32_t num_read = lt_flash_read(offset + IMAGE_PUBLIC_KEY_OFFSET, public_key, sizeof(public_key));
+	if (num_read != sizeof(public_key))
+		return INVALID;
+
+	if (memcmp(public_key, IMAGE_PUBLIC_KEY, sizeof(public_key)) == 0)
+		return ENABLED;
+
+	public_key[0] = ~(public_key[0]);
+	if (memcmp(public_key, IMAGE_PUBLIC_KEY, sizeof(public_key)) == 0)
+		return DISABLED;
+
+	return INVALID;
+}
+
+static bool lt_ota_set_image_enabled(uint8_t index, bool new_enabled) {
+	uint32_t offset;
+	if (!lt_ota_get_image_offset(index, &offset))
+		return false;
+
+	_irqL irqL;
+	uint8_t *header = (uint8_t *)malloc(FLASH_SECTOR_SIZE);
+
+	rtw_enter_critical(NULL, &irqL);
+	device_mutex_lock(RT_DEV_LOCK_FLASH);
+	flash_stream_read(&lt_flash_obj, offset, FLASH_SECTOR_SIZE, header);
+
+	bool enabled = header[IMAGE_PUBLIC_KEY_OFFSET] == IMAGE_PUBLIC_KEY[0];
+	if (enabled != new_enabled) {
+		// negate first byte of OTA signature
+		header[0] = ~(header[0]);
+		// negate first byte of public key
+		header[IMAGE_PUBLIC_KEY_OFFSET] = ~(header[IMAGE_PUBLIC_KEY_OFFSET]);
+
+		// write to flash
+		hal_flash_sector_erase(lt_flash_obj.phal_spic_adaptor, offset);
+		hal_flash_burst_write(lt_flash_obj.phal_spic_adaptor, FLASH_SECTOR_SIZE, offset, header);
+	}
+
+	device_mutex_unlock(RT_DEV_LOCK_FLASH);
+	rtw_exit_critical(NULL, &irqL);
+	free(header);
+
+	return true;
+}
+
+// public interface implementation
 
 lt_ota_type_t lt_ota_get_type() {
 	return OTA_TYPE_DUAL;
 }
 
 bool lt_ota_is_valid(uint8_t index) {
-	return false;
+	return lt_ota_get_image_state(index) != INVALID;
 }
 
 uint8_t lt_ota_dual_get_current() {
-	return 0;
+	// ambz2 uses virtual memory, so we can't use function address to determine active image
+	// use the SDK instead
+	return sys_update_ota_get_curr_fw_idx();
 }
 
 uint8_t lt_ota_dual_get_stored() {
-	return 0;
+	// bootloader prioritizes FW1 if both are valid
+	return lt_ota_get_image_state(1) == ENABLED ? 1 : 2;
 }
 
 bool lt_ota_switch(bool revert) {
-	return false;
+	uint8_t current = lt_ota_dual_get_current();
+	uint8_t stored	= lt_ota_dual_get_stored();
+	if ((current == stored) == revert)
+		return true;
+
+	uint8_t to_enable  = lt_ota_get_other_index(stored);
+	uint8_t to_disable = stored;
+
+	if (!lt_ota_is_valid(to_enable))
+		return false;
+
+	// enable first, so there is always at least one enabled image
+	if (!lt_ota_set_image_enabled(to_enable, true))
+		return false;
+	if (!lt_ota_set_image_enabled(to_disable, false))
+		return false;
+
+	return true;
 }

cores/realtek-ambz2/base/lt_defs.h

@@ -7,4 +7,5 @@
 #define LT_HAS_LWIP2	1
 #define LT_HAS_MBEDTLS	1
 #define LT_HAS_PRINTF	1
+#define LT_HAS_OTA		1
 #define LT_HW_BLE		1