What does request_irq () do inside?

Question

As I know, it "selects an interrupt line", but

> what is happening after request_irq()?
> How a particular handler is getting called on receiving interrupt?

Can someone explain this with snipet code?

Answer 1

what happens after request_irq ()?

The device driver registers an interrupt handler and includes the specified interrupt line for processing by calling request_irq ().

call flow: -

• request_irq () -> setup_irq () to register struct irqaction.
• setup_irq () -> start_irq_thread () to create a kernel thread to serve the interrupt string.

do_irqd(). , - .

request_irq() ISR ( ) start_irq_thread(). start_irq_thread() , ISR.

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, PIC CPU.

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. . ISR ( IRQ). - . ".

http://wiki.osdev.org/Interrupts