Edge triggering and level triggering of Linux interruptions

* Handle_edge_irq-edge type IRQ handler
* @ Irq: the interrupt number
* @ Desc: the interrupt description structure for this irq
*
* Interrupt occures on the falling and/or rising edge of a hardware
* Signal. The occurence is latched into the irq controller hardware
* And must be acked in order to be reenabled. After the ack another
* Interrupt can happen on the same source even before the first one
* Is handled by the assosiacted event handler. If this happens it
* Might be necessary to disable (mask) the interrupt depending on
* Controller hardware. This requires to reenable the interrupt inside
* Of the loop which handles the interrupts which have arrived while
* The handler was running. If all pending interrupts are handled,
* Loop is left.
*/

* Handle_level_irq-Level type irq handler
* @ Irq: the interrupt number
* @ Desc: the interrupt description structure for this irq
*
* Level type interrupts are active as long as the hardware line has
* The active level. This may require to mask the interrupt and unmask
* It after the associated handler has acknowledged the device, so
* Interrupt line is back to inactive.
*/

//

Handle_level_irqirqreturn_t action_ret
Spin_lockMask_ack_irq
Desckstat_incr_irqs_this_cpu
* If its disabled or no action available
* Keep it masked and get out of here
*/Action
Descspin_unlock
Action_ret note_interrupt
Spin_lockdesc
Descdescout_unlockspin_unlockEXPORT_SYMBOL_GPL
Handle_edge_irqspin_lock
Desc
* If we're currently running this IRQ, or its disabled,
* We shouldn't process the IRQ. Mark it pending, handle
* The necessary masking and go out
*/Descmask_ack_irqkstat_incr_irqs_this_cpu
Desc
Desc
Irqreturn_t action_ret
Desc
* When another irq arrived while we were handling
* One, we cocould have masked the irq.
* Renable it, if it was not disabled in meantime.
*/Descdesc
Descspin_unlockaction_ret note_interruptspin_lock

Descout_unlockspin_unlock