Device Drivers

Purpose

Guide agents through Linux kernel device driver development: the driver model (platform_driver, i2c_driver, spi_driver), character device lifecycle, IRQ handling including threaded IRQs, DMA engine API, regmap for register abstraction, runtime power management, and udev rules for userspace device nodes.

When to Use

• Writing a platform driver for memory-mapped hardware
• Implementing a character device with read/write/ioctl
• Handling hardware interrupts (hard IRQ vs threaded)
• Setting up DMA coherent or streaming mappings
• Abstracting register access with regmap
• Configuring udev rules for /dev node permissions

Workflow

1. Driver model overview