API Reference

This section provides quick lookup pages for common Linux userspace and kernel APIs used in the labs.

The goal is not to replace the Linux man pages or kernel documentation. Instead, this section explains each API in the context of the lab code, common embedded Linux usage, and typical mistakes found during development.

API Groups

Group	Example APIs
POSIX I/O	open, read, write, close, fcntl, pipe, dup, errno
Process and Signal	fork, sigaction, sigprocmask, kill, waitpid
Network Socket	socket, bind, listen, accept, connect, recv, send, setsockopt, inet_ntop
Event Loop	epoll_create1, epoll_ctl, epoll_wait, timerfd_create, timerfd_settime, signalfd, eventfd, poll, select
IPC	socketpair, sendmsg, recvmsg, SCM_RIGHTS, shm_open, ftruncate, mmap, mq_open, sem_init, sem_wait, sem_post
Kernel Driver	file_operations, alloc_chrdev_region, cdev_add, device_create, copy_to_user, poll_wait, fasync_helper, devm_gpiod_get
Subsystem	devm_iio_device_alloc, iio_push_to_buffers, input_report_key, input_sync, gpiod_to_irq, devm_hwmon_device_register_with_info

Documentation Style

Each API page follows a consistent layout:

• Purpose
• Header
• Prototype
• Parameters
• Return Value
• Minimal Example
• Common Pitfalls
• Related Topics

Refactor Status

Phase 6 expands the API reference from topic-level summaries into focused per-API lookup pages. Phase 8 adds subsystem-focused API pages for IIO, Input, GPIO, and hwmon. Phase 10 adds POSIX I/O, process/signal, and network socket API references.

Build and Platform Driver Helpers

Phase 11 adds a small set of kernel driver helper references used by platform-driver and Device Tree workflows:

• module_platform_driver()
• struct platform_driver
• struct of_device_id