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/*
* 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 (desc->status & IRQ_PER_CPU) {
irqreturn_t action_ret;
/*
* No locking required for CPU-local interrupts:
*/
desc->handler->ack(irq);
action_ret = handle_IRQ_event(irq, regs, desc->action);
desc->handler->end(irq);
return 1;
}
spin_lock(&desc->lock);
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);
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;
}
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