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+# UP - Embedded Linux Update Server
+
+A Go-based HTTP server for managing embedded Linux system updates, designed for Orange Pi Zero 2W (Allwinner H618) and similar ARM-based devices.
+
+## Overview
+
+This server provides a web interface and REST API for:
+- Uploading and managing boot files (U-Boot, kernel, DTB)
+- Editing extlinux boot configuration
+- Monitoring system temperature
+- Remote system reboot
+- File version tracking
+
+## Project Structure
+
+```
+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:
+
+```env
+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:**
+```bash
+curl http://localhost:8989/api/temperature
+# Response: {"success":true,"temperature":45.2,"unit":"Celsius"}
+```
+
+**Upload File:**
+```bash
+curl -X POST -F "type=kernel" -F "file=@Image.gz" http://localhost:8989/api/upload
+```
+
+**Reboot System:**
+```bash
+curl -X POST http://localhost:8989/api/reboot
+```
+
+**Read Boot Config:**
+```bash
+curl http://localhost:8989/api/extlinux
+```
+
+**Write Boot Config:**
+```bash
+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
+
+```bash
+# 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