litzfw

A freestanding hardware abstraction library for LitziumOS, providing portable access to UART, GPIO, timers, display, and interrupt handling across multiple platforms.

Platform Support

litzfw currently supports:

• x86-64 — UART (16550), Timers (PIT)
• Raspberry Pi 3/4 — UART (PL011), GPIO (BCM), Timers (BCM), Display (VideoCore mailbox)

Features

• Hardware Abstraction Layer (HAL) — Clean interfaces for common peripherals
• Freestanding — No dependencies on standard library or operating system services
• Modular drivers — Pluggable implementations for different SoCs and platforms
• Interrupt handling — IRQ management and routing
• Multi-platform — Shared abstractions across ARM and x86 architectures

Getting Started

Prerequisites

• CMake 3.10+
• C compiler (GCC, Clang, or compatible)
• Make or Ninja build system

Building

cmake -B build
cmake --build build

The library produces a static archive that can be linked into your baremetal or kernel project.

Architecture

litzfw is organized into three main components:

HAL (Hardware Abstraction Layer)

Defined in hal/, these headers provide platform-agnostic interfaces:

• hal_uart.h — Serial communication
• hal_gpio.h — General-purpose I/O
• hal_timer.h — Timing and periodic interrupts
• hal_display.h — Display output
• hal_irq.h — Interrupt handling
• hal_i2c.h — I2C bus (planned)
• hal_spi.h — SPI bus (planned)

Drivers

Implementations in drivers/ and bsp/:

• drivers/ — Device drivers (UART, GPIO, timer implementations)
• bsp/ — Board Support Package with platform-specific initialization

Core

Infrastructure in include/:

• litzfw_types.h — Common types
• litzfw_mmio.h — Memory-mapped I/O utilities
• litzfw_compiler.h — Compiler-specific macros and attributes

Porting to a New Platform

To port litzfw to a new platform:

1. Create a new BSP directory in bsp/
2. Implement platform initialization (bsp_*.c)
3. Implement or reuse device drivers in drivers/
4. Update CMakeLists.txt to include new platform

License

See LICENSE for details.