2 * linux/kernel/irq/handle.c
4 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
6 * This file contains the core interrupt handling code.
10 #include <linux/module.h>
11 #include <linux/random.h>
12 #include <linux/interrupt.h>
13 #include <linux/kernel_stat.h>
15 #include "internals.h"
18 * Linux has a controller-independent interrupt architecture.
19 * Every controller has a 'controller-template', that is used
20 * by the main code to do the right thing. Each driver-visible
21 * interrupt source is transparently wired to the appropriate
22 * controller. Thus drivers need not be aware of the
23 * interrupt-controller.
25 * The code is designed to be easily extended with new/different
26 * interrupt controllers, without having to do assembly magic or
27 * having to touch the generic code.
29 * Controller mappings for all interrupt sources:
31 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = {
33 .status = IRQ_DISABLED,
35 .lock = SPIN_LOCK_UNLOCKED,
37 .affinity = CPU_MASK_ALL
43 * What should we do if we get a hw irq event on an illegal vector?
44 * Each architecture has to answer this themself.
46 static void ack_bad(unsigned int irq)
54 static void noop(unsigned int irq)
58 static unsigned int noop_ret(unsigned int irq)
64 * Generic no controller implementation
66 struct hw_interrupt_type no_irq_type = {
77 * Special, empty irq handler:
79 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
85 * handle_IRQ_event - irq action chain handler
86 * @irq: the interrupt number
87 * @regs: pointer to a register structure
88 * @action: the interrupt action chain for this irq
90 * Handles the action chain of an irq event
92 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
93 struct irqaction *action)
95 irqreturn_t ret, retval = IRQ_NONE;
96 unsigned int status = 0;
98 if (!(action->flags & SA_INTERRUPT))
102 ret = action->handler(irq, action->dev_id, regs);
103 if (ret == IRQ_HANDLED)
104 status |= action->flags;
106 action = action->next;
109 if (status & SA_SAMPLE_RANDOM)
110 add_interrupt_randomness(irq);
117 * __do_IRQ - original all in one highlevel IRQ handler
118 * @irq: the interrupt number
119 * @regs: pointer to a register structure
121 * __do_IRQ handles all normal device IRQ's (the special
122 * SMP cross-CPU interrupts have their own specific
125 * This is the original x86 implementation which is used for every
128 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
130 struct irq_desc *desc = irq_desc + irq;
131 struct irqaction *action;
134 kstat_this_cpu.irqs[irq]++;
135 if (CHECK_IRQ_PER_CPU(desc->status)) {
136 irqreturn_t action_ret;
139 * No locking required for CPU-local interrupts:
142 desc->chip->ack(irq);
143 action_ret = handle_IRQ_event(irq, regs, desc->action);
144 desc->chip->end(irq);
148 spin_lock(&desc->lock);
150 desc->chip->ack(irq);
152 * REPLAY is when Linux resends an IRQ that was dropped earlier
153 * WAITING is used by probe to mark irqs that are being tested
155 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
156 status |= IRQ_PENDING; /* we _want_ to handle it */
159 * If the IRQ is disabled for whatever reason, we cannot
160 * use the action we have.
163 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
164 action = desc->action;
165 status &= ~IRQ_PENDING; /* we commit to handling */
166 status |= IRQ_INPROGRESS; /* we are handling it */
168 desc->status = status;
171 * If there is no IRQ handler or it was disabled, exit early.
172 * Since we set PENDING, if another processor is handling
173 * a different instance of this same irq, the other processor
174 * will take care of it.
176 if (unlikely(!action))
180 * Edge triggered interrupts need to remember
182 * This applies to any hw interrupts that allow a second
183 * instance of the same irq to arrive while we are in do_IRQ
184 * or in the handler. But the code here only handles the _second_
185 * instance of the irq, not the third or fourth. So it is mostly
186 * useful for irq hardware that does not mask cleanly in an
190 irqreturn_t action_ret;
192 spin_unlock(&desc->lock);
194 action_ret = handle_IRQ_event(irq, regs, action);
196 spin_lock(&desc->lock);
198 note_interrupt(irq, desc, action_ret, regs);
199 if (likely(!(desc->status & IRQ_PENDING)))
201 desc->status &= ~IRQ_PENDING;
203 desc->status &= ~IRQ_INPROGRESS;
207 * The ->end() handler has to deal with interrupts which got
208 * disabled while the handler was running.
210 desc->chip->end(irq);
211 spin_unlock(&desc->lock);