2 * linux/kernel/irq/handle.c
4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
7 * This file contains the core interrupt handling code.
9 * Detailed information is available in Documentation/DocBook/genericirq
13 #include <linux/irq.h>
14 #include <linux/module.h>
15 #include <linux/random.h>
16 #include <linux/interrupt.h>
17 #include <linux/kernel_stat.h>
19 #include "internals.h"
22 * handle_bad_irq - handle spurious and unhandled irqs
25 handle_bad_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
27 kstat_this_cpu.irqs[irq]++;
32 * Linux has a controller-independent interrupt architecture.
33 * Every controller has a 'controller-template', that is used
34 * by the main code to do the right thing. Each driver-visible
35 * interrupt source is transparently wired to the appropriate
36 * controller. Thus drivers need not be aware of the
37 * interrupt-controller.
39 * The code is designed to be easily extended with new/different
40 * interrupt controllers, without having to do assembly magic or
41 * having to touch the generic code.
43 * Controller mappings for all interrupt sources:
45 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = {
47 .status = IRQ_DISABLED,
49 .handle_irq = handle_bad_irq,
51 .lock = SPIN_LOCK_UNLOCKED,
53 .affinity = CPU_MASK_ALL
59 * What should we do if we get a hw irq event on an illegal vector?
60 * Each architecture has to answer this themself.
62 static void ack_bad(unsigned int irq)
70 static void noop(unsigned int irq)
74 static unsigned int noop_ret(unsigned int irq)
80 * Generic no controller implementation
82 struct irq_chip no_irq_chip = {
93 * Special, empty irq handler:
95 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
101 * handle_IRQ_event - irq action chain handler
102 * @irq: the interrupt number
103 * @regs: pointer to a register structure
104 * @action: the interrupt action chain for this irq
106 * Handles the action chain of an irq event
108 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
109 struct irqaction *action)
111 irqreturn_t ret, retval = IRQ_NONE;
112 unsigned int status = 0;
114 if (!(action->flags & SA_INTERRUPT))
118 ret = action->handler(irq, action->dev_id, regs);
119 if (ret == IRQ_HANDLED)
120 status |= action->flags;
122 action = action->next;
125 if (status & SA_SAMPLE_RANDOM)
126 add_interrupt_randomness(irq);
133 * __do_IRQ - original all in one highlevel IRQ handler
134 * @irq: the interrupt number
135 * @regs: pointer to a register structure
137 * __do_IRQ handles all normal device IRQ's (the special
138 * SMP cross-CPU interrupts have their own specific
141 * This is the original x86 implementation which is used for every
144 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
146 struct irq_desc *desc = irq_desc + irq;
147 struct irqaction *action;
150 kstat_this_cpu.irqs[irq]++;
151 if (CHECK_IRQ_PER_CPU(desc->status)) {
152 irqreturn_t action_ret;
155 * No locking required for CPU-local interrupts:
158 desc->chip->ack(irq);
159 action_ret = handle_IRQ_event(irq, regs, desc->action);
160 desc->chip->end(irq);
164 spin_lock(&desc->lock);
166 desc->chip->ack(irq);
168 * REPLAY is when Linux resends an IRQ that was dropped earlier
169 * WAITING is used by probe to mark irqs that are being tested
171 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
172 status |= IRQ_PENDING; /* we _want_ to handle it */
175 * If the IRQ is disabled for whatever reason, we cannot
176 * use the action we have.
179 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
180 action = desc->action;
181 status &= ~IRQ_PENDING; /* we commit to handling */
182 status |= IRQ_INPROGRESS; /* we are handling it */
184 desc->status = status;
187 * If there is no IRQ handler or it was disabled, exit early.
188 * Since we set PENDING, if another processor is handling
189 * a different instance of this same irq, the other processor
190 * will take care of it.
192 if (unlikely(!action))
196 * Edge triggered interrupts need to remember
198 * This applies to any hw interrupts that allow a second
199 * instance of the same irq to arrive while we are in do_IRQ
200 * or in the handler. But the code here only handles the _second_
201 * instance of the irq, not the third or fourth. So it is mostly
202 * useful for irq hardware that does not mask cleanly in an
206 irqreturn_t action_ret;
208 spin_unlock(&desc->lock);
210 action_ret = handle_IRQ_event(irq, regs, action);
212 spin_lock(&desc->lock);
214 note_interrupt(irq, desc, action_ret, regs);
215 if (likely(!(desc->status & IRQ_PENDING)))
217 desc->status &= ~IRQ_PENDING;
219 desc->status &= ~IRQ_INPROGRESS;
223 * The ->end() handler has to deal with interrupts which got
224 * disabled while the handler was running.
226 desc->chip->end(irq);
227 spin_unlock(&desc->lock);