Kernel Driver API Reference

This section collects Linux kernel APIs used throughout the kernel driver learning path, including driver core, platform drivers, DMA Engine, character devices, event notification, synchronization, GPIO, IRQ, and deferred execution.

Driver Core

API	Purpose
Driver Core APIs	Register buses, devices, and drivers and understand matching and probe lifecycle

Platform Driver

API	Purpose
module_platform_driver()	Register a platform driver using the standard module initialization and cleanup helpers.
struct platform_driver	Define probe, remove, matching, and driver metadata for a platform driver.
struct of_device_id	Define Device Tree compatible matching entries for a driver.

DMA Engine

API	Purpose
DMA Engine APIs	Allocate DMA channels, prepare and submit transactions, track DMA cookies, query transaction status and residue, handle completion callbacks, manage cyclic DMA, and terminate and synchronize DMA activity

Character Device Registration

API	Purpose
file_operations	Define VFS callbacks for a character device
alloc_chrdev_region	Allocate a dynamic device number range
cdev_add	Register a character device with the VFS
class_create	Create a sysfs class for device nodes
device_create	Create a device object and /dev node
misc_register	Register a simple misc character device

User Access and Control Plane

API	Purpose
copy_to_user	Copy data from kernel to user space
copy_from_user	Copy data from user space to kernel
ioctl	Implement command-based control plane
sysfs attributes	Expose simple device attributes

Blocking I/O and Event Notification

API	Purpose
wait queues	Sleep until a condition becomes true
poll_wait	Integrate driver readiness with poll/epoll
non-blocking I/O	Implement O_NONBLOCK behavior
fasync_helper	Register or unregister asynchronous listeners for SIGIO

Locking, GPIO, and IRQ

API	Purpose
spinlock	Protect shared state accessed from Process Context and IRQ Context using an interrupt-safe spinlock.
mutex	Protect shared state in sleepable contexts such as Process Context, workqueues, and kernel threads.
rw_semaphore	Reader-writer synchronization allowing multiple concurrent readers.
devm_gpiod_get	Get GPIO descriptors from Device Tree
devm_request_threaded_irq	Register threaded IRQ handlers

Deferred Execution

API	Purpose
workqueue	Execute deferred work in process context using kernel worker threads
kthread	Create and manage long-lived kernel execution threads

Related Topics

• Kernel Driver Topics