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>
14 #include <linux/vs_base.h>
15 #include <linux/vs_context.h>
17 #include "internals.h"
20 * Linux has a controller-independent interrupt architecture.
21 * Every controller has a 'controller-template', that is used
22 * by the main code to do the right thing. Each driver-visible
23 * interrupt source is transparently wired to the apropriate
24 * controller. Thus drivers need not be aware of the
25 * interrupt-controller.
27 * The code is designed to be easily extended with new/different
28 * interrupt controllers, without having to do assembly magic or
29 * having to touch the generic code.
31 * Controller mappings for all interrupt sources:
33 irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
35 .status = IRQ_DISABLED,
36 .handler = &no_irq_type,
37 .lock = SPIN_LOCK_UNLOCKED
42 * Generic 'no controller' code
44 static void end_none(unsigned int irq) { }
45 static void enable_none(unsigned int irq) { }
46 static void disable_none(unsigned int irq) { }
47 static void shutdown_none(unsigned int irq) { }
48 static unsigned int startup_none(unsigned int irq) { return 0; }
50 static void ack_none(unsigned int irq)
53 * 'what should we do if we get a hw irq event on an illegal vector'.
54 * each architecture has to answer this themself.
59 struct hw_interrupt_type no_irq_type = {
61 .startup = startup_none,
62 .shutdown = shutdown_none,
63 .enable = enable_none,
64 .disable = disable_none,
71 * Special, empty irq handler:
73 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
79 * Have got an event to handle:
81 fastcall int handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
82 struct irqaction *action)
84 int ret, retval = 0, status = 0;
86 if (!(action->flags & SA_INTERRUPT))
90 ret = action->handler(irq, action->dev_id, regs);
91 if (ret == IRQ_HANDLED)
92 status |= action->flags;
94 action = action->next;
97 if (status & SA_SAMPLE_RANDOM)
98 add_interrupt_randomness(irq);
105 * do_IRQ handles all normal device IRQ's (the special
106 * SMP cross-CPU interrupts have their own specific
109 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
111 irq_desc_t *desc = irq_desc + irq;
112 struct irqaction * action;
115 kstat_this_cpu.irqs[irq]++;
116 if (CHECK_IRQ_PER_CPU(desc->status)) {
117 irqreturn_t action_ret;
120 * No locking required for CPU-local interrupts:
122 if (desc->handler->ack)
123 desc->handler->ack(irq);
124 action_ret = handle_IRQ_event(irq, regs, desc->action);
125 desc->handler->end(irq);
129 spin_lock(&desc->lock);
130 if (desc->handler->ack)
131 desc->handler->ack(irq);
133 * REPLAY is when Linux resends an IRQ that was dropped earlier
134 * WAITING is used by probe to mark irqs that are being tested
136 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
137 status |= IRQ_PENDING; /* we _want_ to handle it */
140 * If the IRQ is disabled for whatever reason, we cannot
141 * use the action we have.
144 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
145 action = desc->action;
146 status &= ~IRQ_PENDING; /* we commit to handling */
147 status |= IRQ_INPROGRESS; /* we are handling it */
149 desc->status = status;
152 * If there is no IRQ handler or it was disabled, exit early.
153 * Since we set PENDING, if another processor is handling
154 * a different instance of this same irq, the other processor
155 * will take care of it.
157 if (unlikely(!action))
161 * Edge triggered interrupts need to remember
163 * This applies to any hw interrupts that allow a second
164 * instance of the same irq to arrive while we are in do_IRQ
165 * or in the handler. But the code here only handles the _second_
166 * instance of the irq, not the third or fourth. So it is mostly
167 * useful for irq hardware that does not mask cleanly in an
171 irqreturn_t action_ret;
173 spin_unlock(&desc->lock);
175 action_ret = handle_IRQ_event(irq, regs, action);
177 spin_lock(&desc->lock);
179 note_interrupt(irq, desc, action_ret, regs);
180 if (likely(!(desc->status & IRQ_PENDING)))
182 desc->status &= ~IRQ_PENDING;
184 desc->status &= ~IRQ_INPROGRESS;
188 * The ->end() handler has to deal with interrupts which got
189 * disabled while the handler was running.
191 desc->handler->end(irq);
192 spin_unlock(&desc->lock);