/* * linux/kernel/irq/handle.c * * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar * * This file contains the core interrupt handling code. */ #include <linux/irq.h>#include <linux/module.h>#include <linux/random.h>#include <linux/interrupt.h>#include <linux/kernel_stat.h> #include "internals.h" /* * Linux has a controller-independent interrupt architecture. * Every controller has a 'controller-template', that is used * by the main code to do the right thing. Each driver-visible * interrupt source is transparently wired to the apropriate * controller. Thus drivers need not be aware of the * interrupt-controller. * * The code is designed to be easily extended with new/different * interrupt controllers, without having to do assembly magic or * having to touch the generic code. * * Controller mappings for all interrupt sources: */irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {	[0 ... NR_IRQS-1] = {		.status = IRQ_DISABLED,		.handler = &no_irq_type,		.lock = SPIN_LOCK_UNLOCKED	}}; /* * Generic 'no controller' code */static void end_none(unsigned int irq) { }static void enable_none(unsigned int irq) { }static void disable_none(unsigned int irq) { }static void shutdown_none(unsigned int irq) { }static unsigned int startup_none(unsigned int irq) { return 0; } static void ack_none(unsigned int irq){	/*	 * 'what should we do if we get a hw irq event on an illegal vector'.	 * each architecture has to answer this themself.	 */	ack_bad_irq(irq);} struct hw_interrupt_type no_irq_type = {	.typename = 	"none",	.startup = 	startup_none,	.shutdown = 	shutdown_none,	.enable = 	enable_none,	.disable = 	disable_none,	.ack = 		ack_none,	.end = 		end_none,	.set_affinity = NULL}; /* * Special, empty irq handler: */irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs){	return IRQ_NONE;} /* * Have got an event to handle: */fastcall int handle_IRQ_event(unsigned int irq, struct pt_regs *regs,				struct irqaction *action){	int ret, retval = 0, status = 0; 	if (!(action->flags & SA_INTERRUPT))		local_irq_enable(); 	do {		ret = action->handler(irq, action->dev_id, regs);		if (ret == IRQ_HANDLED)			status |= action->flags;		retval |= ret;		action = action->next;	} while (action); 	if (status & SA_SAMPLE_RANDOM)		add_interrupt_randomness(irq);	local_irq_disable(); 	return retval;} /* * do_IRQ handles all normal device IRQ's (the special * SMP cross-CPU interrupts have their own specific * handlers). */fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs){	irq_desc_t *desc = irq_desc + irq;	struct irqaction * action;	unsigned int status; 	kstat_this_cpu.irqs[irq]++;	if (CHECK_IRQ_PER_CPU(desc->status)) {		irqreturn_t action_ret; 		/*		 * No locking required for CPU-local interrupts:		 */		if (desc->handler->ack)			desc->handler->ack(irq);		action_ret = handle_IRQ_event(irq, regs, desc->action);		desc->handler->end(irq);		return 1;	} 	spin_lock(&desc->lock);	if (desc->handler->ack)		desc->handler->ack(irq);	/*	 * REPLAY is when Linux resends an IRQ that was dropped earlier	 * WAITING is used by probe to mark irqs that are being tested	 */	status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);	status |= IRQ_PENDING; /* we _want_ to handle it */ 	/*	 * If the IRQ is disabled for whatever reason, we cannot	 * use the action we have.	 */	action = NULL;	if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {		action = desc->action;		status &= ~IRQ_PENDING; /* we commit to handling */		status |= IRQ_INPROGRESS; /* we are handling it */	}	desc->status = status; 	/*	 * If there is no IRQ handler or it was disabled, exit early.	 * Since we set PENDING, if another processor is handling	 * a different instance of this same irq, the other processor	 * will take care of it.	 */	if (unlikely(!action))		goto out; 	/*	 * Edge triggered interrupts need to remember	 * pending events.	 * This applies to any hw interrupts that allow a second	 * instance of the same irq to arrive while we are in do_IRQ	 * or in the handler. But the code here only handles the _second_	 * instance of the irq, not the third or fourth. So it is mostly	 * useful for irq hardware that does not mask cleanly in an	 * SMP environment.	 */	for (;;) {		irqreturn_t action_ret; 		spin_unlock(&desc->lock); 		action_ret = handle_IRQ_event(irq, regs, action); 		spin_lock(&desc->lock);		if (!noirqdebug)			note_interrupt(irq, desc, action_ret, regs);		if (likely(!(desc->status & IRQ_PENDING)))			break;		desc->status &= ~IRQ_PENDING;	}	desc->status &= ~IRQ_INPROGRESS; out:	/*	 * The ->end() handler has to deal with interrupts which got	 * disabled while the handler was running.	 */	desc->handler->end(irq);	spin_unlock(&desc->lock); 	return 1;}