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标题: [NUC980] Implementing OTA Firmware Update on NUC980 Chili Board [打印本页]

作者: admin 时间: 昨天 16:08
标题: [NUC980] Implementing OTA Firmware Update on NUC980 Chili Board

Linux 5.10 + UBIFS RootFS on SPI NOR (W25Q256) + Dual-Kernel Strategy

This article documents a complete OTA firmware update solution on the NUC980 Chili board (with Winbond W25Q256, 32MB, SPI NOR Flash) using:

Buildroot 2024 / Linux kernel 5.10
UBIFS as root filesystem
Dual-kernel layout (kernel1/kernel2)
Custom U-Boot OTA command
fwupdate userspace tool

The design provides:

UBIFS rootfs on SPI NOR
Safe kernel update via A/B strategy
Automatic copy from kernel2 → kernel1 after validation

1. System Architecture Overview

Flash layout (32MB W25Q256):

[td]

Name	Start	End	Size
WHOLE	0x00000000	0x02000000	32MB
uboot	0x00000000	0x000A0000	640KB
kernel1	0x000A0000	0x004A0000	4MB
kernel2	0x004A0000	0x008A0000	4MB
rootfs	0x008A0000	0x02000000	23MB

Update flow:

System runs kernel1.
OTA writes new kernel to kernel2.
On next boot, U-Boot validates kernel2.
If valid → copy to kernel1.
Reset and boot updated system.

2. Buildroot Setup

Strongly recommended: clone a fresh repository to avoid residual files occupied on kernel image.

$ git clone https://github.com/OpenNuvoton/buildroot_2024
$ cd buildroot_2024
$ make nuvoton_nuc980_chili_defconfig

3. Configure UBIFS as RootFS

$ make menuconfig

Disable RAM filesystem

Filesystem images --->
[ ] initial RAM filesystem linked into linux kernel
[ ] cpio the root filesystem (for use as an initial RAM filesystem)

Enable UBIFS

Filesystem images --->

ubi image containing an ubifs root filesystem

UBIFS parameters (for W25Q256 SPI NOR)

[td]

Parameter	Value
Physical eraseblock size	0x10000
Sub-page size	1
Logical eraseblock size	0xFF80
Minimum I/O unit size	0x1
Maximum logical eraseblock count	374
Additional mkfs options	-F

These values must match the SPI NOR geometry.

4. Linux Kernel Configuration

$ make linux-menuconfig

Remove initramfs

General setup --->
[ ] Boot config support
[ ] Initial RAM filesystem and RAM disk support

Enable MTD / UBI / SPI NOR

Device Drivers  --->
Memory Technology Device (MTD) support  --->
      Partition parsers  --->
         <*> Command line partition table parsing
      Enable UBI - Unsorted block images  --->

UBI Fastmap
SPI NOR device support --->
[ ] Use small 4096 B erase sectors

Important: disable 4K sectors (W25Q256 uses 64K erase blocks).

5. Device Tree Partition Layout

Edit the qspi0 session of ./output/build/linux-custom/arch/arm/boot/dts/nuc980-chili.dts

qspi0: spi@b0060000 { status = "okay"; flash: flash@0 { compatible = "jedec,spi-nor"; #address-cells = <1>; #size-cells = <1>; reg = <0>; spi-max-frequency = <30000000>; partition@0 { label = "WHOLE"; reg = <0x00000000 0x02000000>; }; partition@1 { label = "uboot"; reg = <0x00000000 0x000A0000>; }; partition@2 { label = "kernel1"; reg = <0x000A0000 0x00400000>; }; partition@3 { label = "kernel2"; reg = <0x004A0000 0x00400000>; }; partition@4 { label = "rootfs"; reg = <0x008A0000 0x01760000>; }; };};

6. Prevent Incorrect mdev Mounting

Since 5 partitions exist, modify ./board/nuvoton/nuc9x0/rootfs-chili/etc/mdev.conf

Change last line:

mtdblock([5-9]+) ...

This prevents unwanted yaffs/jffs2 auto-mount attempts.

7. Add OTA Command to U-Boot

Extract U-Boot source:

$ make uboot-patch

Add following files which are in the attached ZIP to ./output/build/uboot-master/common/ directory.

ota_update.c
check_crc.c / .h
crc_checksum.c / .h

nuc980_uboot_ota_update_files.zip

Edit ./output/build/uboot-master/common/Makefile

Add following three lines to the Makefile

obj-y += ota_update.oobj-y += check_crc.oobj-y += crc_checksum.o

This adds a custom ota_update command that:

Validates kernel2
Performs CRC check
Returns success/failure

8. U-Boot Environment Configuration

Create env.txt (The file is also in attached ZIP file)

baudrate=115200bootdelay=1stderr=serialstdin=serialstdout=serialimage1_flash_offset=0xA0000image2_flash_offset=0x4A0000image_size=0x400000image1_ram_offset=0x7fc0image2_ram_offset=0x407fc0dtb_flash_offset=0x90000dtb_ram_offset=0x1800000dtb_size=0x10000setspi=sf probe 0 30000000loadkernel1=sf read ${image1_ram_offset} ${image1_flash_offset} ${image_size}loadkernel2=sf read ${image2_ram_offset} ${image2_flash_offset} ${image_size}eraseflash=sf erase ${image1_flash_offset} ${image_size}copykernel=sf write ${image2_ram_offset} ${image1_flash_offset} ${image_size}loaddtb=sf read ${dtb_ram_offset} ${dtb_flash_offset} ${dtb_size}bootcmd=run setspi;run loaddtb;run loadkernel1;run loadkernel2;if ota_update ${image1_ram_offset} ${image2_ram_offset} ${image_size} ${dtb_ram_offset};then run eraseflash;run copykernel;reset;fi;bootargs=noinitrd ubi.mtd=rootfs root=ubi0:rootfs rootfstype=ubifs rw console=ttyS0 rdinit=/sbin/init mem=64M

Boot logic:

Always load both kernels
If kernel2 valid and differ from kernel1 → copy to kernel1
Reset system
Otherwise continue booting kernel1

9. Build Everything

$ make

10. Build fwupdate Tool

Setup toolchain:

$ cd
$ source ~/buildroot_2024/output/host/environment_setup

Clone and build:

$ git clone https://github.com/OpenNuvoton/NUC980_Linux_Applications
$ cd NUC980_Linux_Applications/demos/fwupdate
$ make

Copy into rootfs:

$ cp fwupdate ~/buildroot_2024/output/target/usr/bin
$ cd ~/buildroot_2024
$ make

11. Flash Images

From ./output/images directory, use NuWriter to program following files to SPI Flash.

[td]

File	Type	Addr/Offset
uboot.bin	Loader	0xE00000
env.txt	Environment	0x0080000
nuc980-chili.dtb	Data	0x0090000
uImage (kernel1)	Data	0x00A0000
uImage (kernel2)	Data	0x04A0000
rootfs.ubi	Data	0x08A0000

Ensure full erase of rootfs partition before flashing.

12. OTA Update Procedure

For future updates:

Use NuWriter to pack new kernel image (targeting kernel2 offset).
Transfer pack file to device.
Run fwupdate to overwrite kernel2 region.
Reboot.
U-Boot validates and copies kernel2 → kernel1.
System reboots into updated firmware.

Final Notes

This design provides:

UBIFS rootfs on SPI NOR
Dual-kernel safety
CRC-verified upgrade
No NAND required
No initramfs dependency
Deterministic boot behavior

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