Kernel Driver Topics¶

This section organizes Linux kernel driver concepts into reusable topic pages.

Unlike the original Day-based labs, these topics are organized by subject area rather than chronological learning order. Each module can be studied independently while still following a recommended progression.

Driver Foundation¶

Core concepts required before developing Linux kernel drivers.

Topic	Main Idea	Related Labs
Linux Driver Model	Understand device, driver, bus, matching, probe, and sysfs hierarchy	Day71
Platform Bus	Understand platform devices, platform drivers, matching, and Device Tree integration	Day72
Character Device Basics	Register a character device and expose a file interface	Day05, Day06
Platform Driver and Device Tree Binding	Bind hardware description to a driver using `compatible`	Day08, Day09, Day10

DMA Engine¶

Learn how Linux abstracts DMA hardware into reusable transaction-based interfaces.

Topic	Main Idea	Related Labs
Linux DMA Engine Framework	Understand the DMA Engine architecture and framework abstraction	Day99
DMA Controller Driver	Understand DMA controllers, DMA channels, channel allocation, and Device Tree integration	Day100
DMA Descriptor	Understand DMA transaction objects, descriptor ownership, preparation, submission, queue lifecycle, and controller scheduling	Day101, Day102
DMA Completion and Transaction Status	Understand hardware completion, cookie completion, transaction status, residue reporting, deferred callback processing, and descriptor finalization	Day103
DMA Termination and Synchronization	Understand DMA termination, completion synchronization, shutdown races, and safe client resource cleanup	Day104
Cyclic DMA	Understand long-running cyclic DMA transactions, periods, period callbacks, producer/consumer behavior, residue, and cyclic DMA shutdown	Day105
DMA Slave Configuration	Configure peripheral addresses, transfer widths, burst behavior, and understand how slave configuration combines with transaction descriptors.	Day106
DMA Slave Transfer	Prepare and execute one-shot slave DMA transfers using DMA-mapped buffers, single or scatter-gather transactions, completion handling, and safe resource cleanup	Day107
DMA Scatter-Gather Transfer	Build and map scatter-gather memory, distinguish original SG entries from DMA-visible segments, and prepare slave SG transactions with `dmaengine_prep_slave_sg()`	Day108
DMA Client Driver Architecture	Coordinate request-based and continuous DMA transfers, persistent mappings, buffer ownership, producer-consumer flow, completion, and safe cleanup	Day109, Day110

Event Notification and Asynchronous I/O¶

Learn how Linux drivers notify user space and integrate with event-driven I/O.

Topic	Main Idea	Related Labs
Blocking and Non-blocking I/O	Implement blocking and non-blocking read paths using wait queues	Day12, Day14, Day18, Day50
Wait Queue and poll Support	Integrate drivers with `poll()`, `select()`, and `epoll()`	Day12, Day15, Day50, Day51
epoll	Scale event notification using Interest List and Ready List	Day86
fasync and SIGIO	Notify user space asynchronously using signals	Day52

Interrupts and Deferred Execution¶

Learn how interrupt handling is separated from deferred execution.

Topic	Main Idea	Related Labs
GPIO and IRQ Driver	Build GPIO interrupt drivers using gpiod and IRQ handlers	Day09, Day11, Day13
Deferred Work Selection	Compare Threaded IRQ, Workqueue, kthread_worker, and Dedicated kthread	Day80, Day81, Day82, Day83

Driver Synchronization¶

Learn how Linux protects shared kernel resources.

Topic	Main Idea	Related Labs
Kernel Locking	Protect shared kernel data using spinlocks, mutexes, and reader-writer semaphores	Day88

Driver Control Plane¶

Learn how drivers expose configuration interfaces separately from the data path.

Topic	Main Idea	Related Labs
Driver Control Plane	Separate data path from configuration path using `ioctl()` and `sysfs`	Day16, Day17

Core Driver Model¶

Device Tree
        ↓
platform_device
        ↓
platform_match()
        ↓
platform_driver.probe()
        ↓
initialize hardware and software state
        ↓
file_operations
        ↓
open/read/write/poll/ioctl/release
        ↓
/dev/<name>
        ↓
User-space application

DMA Learning Path¶

Linux DMA Engine Framework
            ↓
DMA Controller Driver
            ↓
DMA Descriptor
            ↓
Descriptor Submission
            ↓
DMA Completion and Transaction Status
            ↓
DMA Termination and Synchronization
            ↓
Cyclic DMA
            ↓
DMA Slave Configuration
            ↓
DMA Slave Transfer
            ↓
DMA Scatter-Gather Transfer
            ↓
DMA Client Driver Architecture

Deferred Execution Learning Path¶

IRQ
        ↓
IRQ Bottom Half
        ↓
Workqueue
        ↓
kthread_worker
        ↓
Deferred Work Selection
        ↓
Wait Queue