Embedded Linux Project

Overview

This repository contains the source code and documentation for an Embedded Linux project, developed as part of the SETI - Embedded Linux course. The project focuses on Linux kernel compilation, device driver development, user-kernel communication, and I2C-based peripheral interaction, all within an ARM-based emulation environment.

A key aspect of this project is the simulation of an ARM Cortex-A9 processor using QEMU, allowing the deployment and testing of low-level Linux systems and custom kernel drivers on an embedded ARM architecture.

Key Features

• ARM Cortex-A9 Emulation & Linux Kernel Compilation

  • Compiled a Linux 5.15.6 kernel for an ARMv7-A architecture.
  • Simulated an ARM CoreTile Express A9x4 Cortex-A9-based expansion board using QEMU.
  • Used a custom QEMU version with an integrated ADXL345 accelerometer emulation.

• Custom I2C Device Driver (pilote_i2c)

  • Developed a Linux kernel driver for the ADXL345 accelerometer.
  • Implemented probe and remove functions using the Linux I2C driver model.
  • Modified the Device Tree for proper driver discovery.

• User-Kernel Communication via Misc Framework

  • Exposed device data to user space using a character device interface.
  • Implemented read and ioctl functions for efficient user-kernel interaction.

• Interrupt Handling & FIFO Buffering

  • Configured hardware interrupts to efficiently collect accelerometer data.
  • Managed a FIFO buffer to store sensor readings asynchronously.

• Concurrency & Multi-Threading Support

  • Implemented thread synchronization mechanisms for multi-process access.
  • Used spinlocks to ensure safe concurrent access to shared resources.

Project Structure

embedded-linux-project/
├── 📁 initramfs_busybox/ # Initramfs with BusyBox (minimal Linux root filesystem)
├── 📁 initramfs_simple/ # Basic initramfs setup for QEMU booting
├── 📁 pilote_i2c/ # ADXL345 I2C device driver source code
├── 📁 qemu-system-arm/ # QEMU binaries and configuration files
├── 📄 .gitignore # Git exclusion rules
└── 📄 README.md # Project documentation (you are here)

Getting Started

Prerequisites

• QEMU (ARM Cortex-A9 emulation)
• Linux Kernel 5.15.6
• ARM Cross-Compiler (arm-linux-gnueabi-gcc)
• BusyBox (for minimal root filesystem)
• Build Essentials (make, gcc, binutils)

Installation & Usage

1. Clone the Repository

   git clone https://github.com/coiti4/embedded-linux-project.git
   cd embedded-linux-project
   

2. Compile the Linux Kernel for ARM

   make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- zImage dtbs modules
   

3. Start QEMU with ARM Cortex-A9 Emulation

   ./qemu-system-arm -M vexpress-a9 -kernel zImage -dtb vexpress-v2p-ca9.dtb -nographic
   

4. Build and Load the I2C Device Driver

   cd pilote_i2c
   make
   insmod adxl345.ko
   

5. Test with the User-Space Application

   ./user_app/main
   

Results

• Successfully compiled and booted Linux on an ARM Cortex-A9 platform.
• Developed a functional I2C device driver for the ADXL345 accelerometer.
• Implemented interrupt-driven data collection with an efficient FIFO buffer.
• Integrated concurrent access control mechanisms for multi-threaded execution.

Future Improvements

• Enhance the driver with additional configuration options for power management.
• Implement DMA support for optimized data transfer.
• Expand user-space utilities to provide a more comprehensive interface.

Contributors

• Agustín Coitinho
• Arthur Ruback
• Irene Asensio

License

This project is licensed under the MIT License. See LICENSE for details.