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 apropriate
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 irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
33 .handler = &no_irq_type,
34 .lock = SPIN_LOCK_UNLOCKED
39 * Generic 'no controller' code
41 static void end_none(unsigned int irq) { }
42 static void enable_none(unsigned int irq) { }
43 static void disable_none(unsigned int irq) { }
44 static void shutdown_none(unsigned int irq) { }
45 static unsigned int startup_none(unsigned int irq) { return 0; }
47 static void ack_none(unsigned int irq)
50 * 'what should we do if we get a hw irq event on an illegal vector'.
51 * each architecture has to answer this themself.
56 struct hw_interrupt_type no_irq_type = {
58 .startup = startup_none,
59 .shutdown = shutdown_none,
60 .enable = enable_none,
61 .disable = disable_none,
68 * Special, empty irq handler:
70 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
76 * Exit an interrupt context. Process softirqs if needed and possible:
80 preempt_count() -= IRQ_EXIT_OFFSET;
81 if (!in_interrupt() && local_softirq_pending())
83 preempt_enable_no_resched();
87 * Have got an event to handle:
89 fastcall int handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
90 struct irqaction *action)
92 int ret, retval = 0, status = 0;
94 if (!(action->flags & SA_INTERRUPT))
98 ret = action->handler(irq, action->dev_id, regs);
99 if (ret == IRQ_HANDLED)
100 status |= action->flags;
102 action = action->next;
105 if (status & SA_SAMPLE_RANDOM)
106 add_interrupt_randomness(irq);
113 * do_IRQ handles all normal device IRQ's (the special
114 * SMP cross-CPU interrupts have their own specific
117 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
119 irq_desc_t *desc = irq_desc + irq;
120 struct irqaction * action;
123 kstat_this_cpu.irqs[irq]++;
124 if (desc->status & IRQ_PER_CPU) {
125 irqreturn_t action_ret;
128 * No locking required for CPU-local interrupts:
130 desc->handler->ack(irq);
131 action_ret = handle_IRQ_event(irq, regs, desc->action);
133 note_interrupt(irq, desc, action_ret);
134 desc->handler->end(irq);
138 spin_lock(&desc->lock);
139 desc->handler->ack(irq);
141 * REPLAY is when Linux resends an IRQ that was dropped earlier
142 * WAITING is used by probe to mark irqs that are being tested
144 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
145 status |= IRQ_PENDING; /* we _want_ to handle it */
148 * If the IRQ is disabled for whatever reason, we cannot
149 * use the action we have.
152 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
153 action = desc->action;
154 status &= ~IRQ_PENDING; /* we commit to handling */
155 status |= IRQ_INPROGRESS; /* we are handling it */
157 desc->status = status;
160 * If there is no IRQ handler or it was disabled, exit early.
161 * Since we set PENDING, if another processor is handling
162 * a different instance of this same irq, the other processor
163 * will take care of it.
165 if (unlikely(!action))
169 * Edge triggered interrupts need to remember
171 * This applies to any hw interrupts that allow a second
172 * instance of the same irq to arrive while we are in do_IRQ
173 * or in the handler. But the code here only handles the _second_
174 * instance of the irq, not the third or fourth. So it is mostly
175 * useful for irq hardware that does not mask cleanly in an
179 irqreturn_t action_ret;
181 spin_unlock(&desc->lock);
183 action_ret = handle_IRQ_event(irq, regs, action);
185 spin_lock(&desc->lock);
187 note_interrupt(irq, desc, action_ret);
188 if (likely(!(desc->status & IRQ_PENDING)))
190 desc->status &= ~IRQ_PENDING;
192 desc->status &= ~IRQ_INPROGRESS;
196 * The ->end() handler has to deal with interrupts which got
197 * disabled while the handler was running.
199 desc->handler->end(irq);
200 spin_unlock(&desc->lock);