up/
├── main.go              # Application entry point
├── go.mod               # Go module definition
├── up.conf              # Environment configuration file
├── api/                 # HTTP handlers
│   ├── frontend/        # Embedded web UI (HTML, CSS, JS)
│   ├── Extlinux.go      # Boot config read/write router
│   ├── ExtlinuxRead.go  # Read extlinux.conf
│   ├── ExtlinuxWrite.go # Write extlinux.conf
│   ├── FileDate.go      # Get file version timestamps
│   ├── HandleReboot.go  # System reboot endpoint
│   ├── HandleTemperature.go # Temperature monitoring
│   ├── HandleUpload.go  # File upload handler
│   ├── MountStatus.go   # Mount status checker
│   └── spa.go           # SPA file server
├── server/              # Server configuration
│   ├── Configure.go     # Route configuration
│   └── Run.go           # Server startup (HTTP/HTTPS)
└── utils/               # Utility functions
    ├── mtd/             # MTD (Memory Technology Device) utilities
    ├── EnsureDir.go     # Directory creation
    ├── GetTargetFilename.go # Filename resolution by type
    ├── LoadEnv.go       # Environment loader
    ├── MountDevice.go   # Device mounting
    └── WriteUbootToDevices.go # U-Boot flashing

Configuration

The server uses up.conf (dotenv format) for configuration:

ENABLE_TLS=false                    # Enable HTTPS
CERT_FILE=cert.crt                  # TLS certificate path
KEY_FILE=privkey.key                # TLS key path
SERVER_ADDRESS=0.0.0.0              # Bind address
SERVER_PORT=8989                    # Bind port
MOUNT_POINT=/media                  # Mount point for target device
DEVICE=/dev/mmcblk1p1               # Target block device
KERNEL_FILE=Image.gz                # Kernel image filename
DTB_FILE=sun50i-h618-orangepi-zero2w.dtb  # Device tree blob
UBOOT_FILE=uboot.env                # U-Boot environment file
EXTLINUX_FILE=extlinux/extlinux.conf # Bootloader config
MAX_FILE_SIZE=200                   # Max upload size (MB)
UBOOT_BIN_FILE=u-boot-sunxi-with-spl.bin # U-Boot binary
UBOOT_MAX_SIZE=1                    # Max U-Boot size (MB)
MMC_BOOT_OFFSET=8192                # MMC boot offset

API Endpoints

Endpoint	Method	Description
`/`	GET	Web UI (SPA)
`/api/mount`	GET	Get mount status
`/api/extlinux`	GET	Read extlinux.conf
`/api/extlinux`	POST	Write extlinux.conf
`/api/filedate`	GET	Get file version date
`/api/temperature`	GET	Get CPU temperature
`/api/upload`	POST	Upload files
`/api/reboot`	POST	Reboot system

API Examples

Get Temperature:

curl http://localhost:8989/api/temperature
# Response: {"success":true,"temperature":45.2,"unit":"Celsius"}

Upload File:

curl -X POST -F "type=kernel" -F "file=@Image.gz" http://localhost:8989/api/upload

Reboot System:

curl -X POST http://localhost:8989/api/reboot

Read Boot Config:

curl http://localhost:8989/api/extlinux

Write Boot Config:

curl -X POST -H "Content-Type: application/json" \
  -d '{"content":"default linux\n  label linux\n  kernel /Image.gz\n"}' \
  http://localhost:8989/api/extlinux

Supported Upload Types

The server supports uploading the following file types:

kernel - Kernel image (Image.gz)
dtb - Device tree blob
uboot_bin - U-Boot bootloader
uboot_env - U-Boot environment
extlinux - Bootloader configuration

Building

# Build
go build -o up

# Run
./up

Requirements

Go 1.26+
Root privileges (for mounting devices and rebooting)
Target storage device (eMMC/SD card)

Features

Web Interface: Embedded SPA frontend for easy management
TLS Support: Optional HTTPS with certificate configuration
Progress Tracking: Real-time upload progress monitoring
Version Tracking: Automatic timestamp logging for uploaded files
Safe Reboot: Graceful unmount and sync before reboot
Temperature Monitoring: CPU thermal sensor readings