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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/irq/handle.c
3 *
4 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
5 *
6 * This file contains the core interrupt handling code.
7 */
8
9#include <linux/irq.h>
10#include <linux/module.h>
11#include <linux/random.h>
12#include <linux/interrupt.h>
13#include <linux/kernel_stat.h>
14
15#include "internals.h"
16
17/*
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
Ingo Molnar06fcb0c2006-06-29 02:24:40 -070021 * interrupt source is transparently wired to the appropriate
Linus Torvalds1da177e2005-04-16 15:20:36 -070022 * controller. Thus drivers need not be aware of the
23 * interrupt-controller.
24 *
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.
28 *
29 * Controller mappings for all interrupt sources:
30 */
Ingo Molnar34ffdb72006-06-29 02:24:40 -070031struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070032 [0 ... NR_IRQS-1] = {
Zhang, Yanmin4f167fb2005-05-16 21:53:43 -070033 .status = IRQ_DISABLED,
Ingo Molnard1bef4e2006-06-29 02:24:36 -070034 .chip = &no_irq_type,
Thomas Gleixner94d39e12006-06-29 02:24:50 -070035 .depth = 1,
Ingo Molnara53da522006-06-29 02:24:38 -070036 .lock = SPIN_LOCK_UNLOCKED,
37#ifdef CONFIG_SMP
38 .affinity = CPU_MASK_ALL
39#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 }
41};
42
43/*
Ingo Molnar77a5afe2006-06-29 02:24:46 -070044 * What should we do if we get a hw irq event on an illegal vector?
45 * Each architecture has to answer this themself.
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 */
Ingo Molnar77a5afe2006-06-29 02:24:46 -070047static void ack_bad(unsigned int irq)
Linus Torvalds1da177e2005-04-16 15:20:36 -070048{
Linus Torvalds1da177e2005-04-16 15:20:36 -070049 ack_bad_irq(irq);
50}
51
Ingo Molnar77a5afe2006-06-29 02:24:46 -070052/*
53 * NOP functions
54 */
55static void noop(unsigned int irq)
56{
57}
58
59static unsigned int noop_ret(unsigned int irq)
60{
61 return 0;
62}
63
64/*
65 * Generic no controller implementation
66 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070067struct hw_interrupt_type no_irq_type = {
Ingo Molnar77a5afe2006-06-29 02:24:46 -070068 .typename = "none",
69 .startup = noop_ret,
70 .shutdown = noop,
71 .enable = noop,
72 .disable = noop,
73 .ack = ack_bad,
74 .end = noop,
Linus Torvalds1da177e2005-04-16 15:20:36 -070075};
76
77/*
78 * Special, empty irq handler:
79 */
80irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
81{
82 return IRQ_NONE;
83}
84
Ingo Molnar8d28bc72006-06-29 02:24:46 -070085/**
86 * handle_IRQ_event - irq action chain handler
87 * @irq: the interrupt number
88 * @regs: pointer to a register structure
89 * @action: the interrupt action chain for this irq
90 *
91 * Handles the action chain of an irq event
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 */
Ingo Molnar2e60bbb2006-06-29 02:24:39 -070093irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
94 struct irqaction *action)
Linus Torvalds1da177e2005-04-16 15:20:36 -070095{
Jan Beulich908dcec2006-06-23 02:06:00 -070096 irqreturn_t ret, retval = IRQ_NONE;
97 unsigned int status = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070098
99 if (!(action->flags & SA_INTERRUPT))
100 local_irq_enable();
101
102 do {
103 ret = action->handler(irq, action->dev_id, regs);
104 if (ret == IRQ_HANDLED)
105 status |= action->flags;
106 retval |= ret;
107 action = action->next;
108 } while (action);
109
110 if (status & SA_SAMPLE_RANDOM)
111 add_interrupt_randomness(irq);
112 local_irq_disable();
113
114 return retval;
115}
116
Ingo Molnar8d28bc72006-06-29 02:24:46 -0700117/**
118 * __do_IRQ - original all in one highlevel IRQ handler
119 * @irq: the interrupt number
120 * @regs: pointer to a register structure
121 *
122 * __do_IRQ handles all normal device IRQ's (the special
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 * SMP cross-CPU interrupts have their own specific
124 * handlers).
Ingo Molnar8d28bc72006-06-29 02:24:46 -0700125 *
126 * This is the original x86 implementation which is used for every
127 * interrupt type.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 */
129fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
130{
Ingo Molnar34ffdb72006-06-29 02:24:40 -0700131 struct irq_desc *desc = irq_desc + irq;
Ingo Molnar06fcb0c2006-06-29 02:24:40 -0700132 struct irqaction *action;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 unsigned int status;
134
135 kstat_this_cpu.irqs[irq]++;
Karsten Wiesef26fdd52005-09-06 15:17:25 -0700136 if (CHECK_IRQ_PER_CPU(desc->status)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 irqreturn_t action_ret;
138
139 /*
140 * No locking required for CPU-local interrupts:
141 */
Ingo Molnard1bef4e2006-06-29 02:24:36 -0700142 if (desc->chip->ack)
143 desc->chip->ack(irq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144 action_ret = handle_IRQ_event(irq, regs, desc->action);
Ingo Molnard1bef4e2006-06-29 02:24:36 -0700145 desc->chip->end(irq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 return 1;
147 }
148
149 spin_lock(&desc->lock);
Ingo Molnard1bef4e2006-06-29 02:24:36 -0700150 if (desc->chip->ack)
151 desc->chip->ack(irq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 /*
153 * REPLAY is when Linux resends an IRQ that was dropped earlier
154 * WAITING is used by probe to mark irqs that are being tested
155 */
156 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
157 status |= IRQ_PENDING; /* we _want_ to handle it */
158
159 /*
160 * If the IRQ is disabled for whatever reason, we cannot
161 * use the action we have.
162 */
163 action = NULL;
164 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
165 action = desc->action;
166 status &= ~IRQ_PENDING; /* we commit to handling */
167 status |= IRQ_INPROGRESS; /* we are handling it */
168 }
169 desc->status = status;
170
171 /*
172 * If there is no IRQ handler or it was disabled, exit early.
173 * Since we set PENDING, if another processor is handling
174 * a different instance of this same irq, the other processor
175 * will take care of it.
176 */
177 if (unlikely(!action))
178 goto out;
179
180 /*
181 * Edge triggered interrupts need to remember
182 * pending events.
183 * This applies to any hw interrupts that allow a second
184 * instance of the same irq to arrive while we are in do_IRQ
185 * or in the handler. But the code here only handles the _second_
186 * instance of the irq, not the third or fourth. So it is mostly
187 * useful for irq hardware that does not mask cleanly in an
188 * SMP environment.
189 */
190 for (;;) {
191 irqreturn_t action_ret;
192
193 spin_unlock(&desc->lock);
194
195 action_ret = handle_IRQ_event(irq, regs, action);
196
197 spin_lock(&desc->lock);
198 if (!noirqdebug)
Alan Cox200803d2005-06-28 20:45:18 -0700199 note_interrupt(irq, desc, action_ret, regs);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 if (likely(!(desc->status & IRQ_PENDING)))
201 break;
202 desc->status &= ~IRQ_PENDING;
203 }
204 desc->status &= ~IRQ_INPROGRESS;
205
206out:
207 /*
208 * The ->end() handler has to deal with interrupts which got
209 * disabled while the handler was running.
210 */
Ingo Molnard1bef4e2006-06-29 02:24:36 -0700211 desc->chip->end(irq);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 spin_unlock(&desc->lock);
213
214 return 1;
215}
216