Add wolfBoot HAL port for RealTek RTL8735B (AmebaPro2)#797
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Pull request overview
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Adds initial wolfBoot HAL enablement for the RealTek RTL8735B (AmebaPro2) platform, including build integration and packaging support for producing a flashable image using the vendor SDK tooling.
Changes:
- Introduces a new RTL8735B HAL implementation and linker script for SRAM-staged boot.
- Adds an SDK shim header to avoid pulling FreeRTOS/CMSIS-OS into the wolfBoot build.
- Adds build system wiring (arch.mk), example config, and a packaging script to generate
flash_ntz.bin.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| tools/scripts/amebapro2_package.sh | Adds packaging flow to convert wolfboot.elf into a vendor-style flash image. |
| hal/rtl8735b/sdk-shim/cmsis_os.h | Provides CMSIS-OS opaque typedefs to compile SDK headers without FreeRTOS. |
| hal/rtl8735b/README | Documents the RTL8735B HAL design, backends, and SDK integration approach. |
| hal/rtl8735b.ld | Defines SRAM layout, RAM start-table placement, and partition symbols. |
| hal/rtl8735b.c | Implements RTL8735B HAL + RAM start-table/trampoline + SDK-backed ext flash/cache hooks. |
| config/examples/rtl8735b.config | Provides an example configuration for RTL8735B builds and partition layout. |
| arch.mk | Adds TARGET=rtl8735b build integration and SDK include/define wiring. |
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| int ext_flash_read(uintptr_t address, uint8_t *data, int len) | ||
| { | ||
| if (len <= 0) { | ||
| return -1; | ||
| } | ||
| #ifdef HAL_BACKEND_SDK | ||
| /* flash_stream_read returns 1 on success; propagate a read failure rather | ||
| * than handing potentially-stale data to the verifier. */ | ||
| if (flash_stream_read(&hal_flash_obj, (uint32_t)address, (uint32_t)len, | ||
| data) != 1) { | ||
| return -1; | ||
| } | ||
| return len; | ||
| #else | ||
| /* TODO(bare): implement via direct SPIC / ROM hal_flash_stream_read. */ | ||
| (void)address; | ||
| (void)data; | ||
| return -1; | ||
| #endif | ||
| } |
Comment on lines
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| int ext_flash_write(uintptr_t address, const uint8_t *data, int len) | ||
| { | ||
| if (len <= 0) { | ||
| return -1; | ||
| } | ||
| #ifdef HAL_BACKEND_SDK | ||
| /* flash_stream_write returns 1 on success; propagate a write failure. */ | ||
| if (flash_stream_write(&hal_flash_obj, (uint32_t)address, (uint32_t)len, | ||
| (uint8_t *)data) != 1) { | ||
| return -1; | ||
| } | ||
| return 0; | ||
| #else | ||
| /* TODO(bare): implement via direct SPIC / ROM hal_flash_burst_write. */ | ||
| (void)address; | ||
| (void)data; | ||
| return -1; | ||
| #endif | ||
| } |
Comment on lines
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| int hal_flash_write(uint32_t address, const uint8_t *data, int len) | ||
| { | ||
| (void)address; | ||
| (void)data; | ||
| (void)len; | ||
| return 0; | ||
| } | ||
|
|
||
| int hal_flash_erase(uint32_t address, int len) | ||
| { | ||
| (void)address; | ||
| (void)len; | ||
| return 0; | ||
| } |
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Adds wolfBoot support for the RealTek RTL8735B (Arm Cortex-M33) as used on the AmebaPro2 EVB. wolfBoot runs as a second-stage verified bootloader and A/B firmware-update engine on top of RealTek's secure-boot ROM -- the non-TrustZone "Model A" integration.
How it boots
RealTek ROM -> boot.bin -> wolfBoot (staged into SRAM via a RealTek RAM start-table) -> verifies the application in external SPI NOR (ECDSA P-256 / SHA-256), applies any pending A/B update, copies the verified image into DDR, and jumps. This reuses wolfBoot's existing RAMBOOT path (
EXT_FLASH+NO_XIP,src/update_ram.c); no new boot assembly is required.What's included
hal/rtl8735b.c/hal/rtl8735b.ld: single-file HAL -- HAL entry points,ext_flash_*over the RealTek SPI NOR, the RAM start-table + trampoline, cache maintenance, a self-containedDEBUG_UARTconsole, and a reset-reason readout. Flash/UART/cache backend selected byHAL_BACKEND(sdk= default/working;bare= scaffold).config/examples/rtl8735b.configand anarch.mktarget block.tools/scripts/rtl8735b_build.sh(compile + SDK-resolved final link) andtools/scripts/amebapro2_package.sh(wrapwolfboot.elfinto a flashableflash_ntz.bin).hal/rtl8735b/test-app/: a minimal DDR test application (also demonstrates servicing the vendor watchdog).docs/Targets.mdsection (build, staging an app, A/B update, watchdog, status/roadmap) andhal/rtl8735b/README.Verified on the AmebaPro2 EVB
DEBUG_UARTconsole and signed boot of an application from the BOOT partition (verify -> copy to DDR -> jump).Follow-ons (not in this PR)
See the "Status and roadmap" list in the
docs/Targets.mdsection: device-bound encrypted updates bound to the Hardware Unique Key (wolfSSL PR #10677), TrustZone-M "Model B", the no-SDK "bare" backend, and measured boot / DICE.