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 * Generic 'no controller' code
45 static void end_none(unsigned int irq) { }
46 static void enable_none(unsigned int irq) { }
47 static void disable_none(unsigned int irq) { }
48 static void shutdown_none(unsigned int irq) { }
49 static unsigned int startup_none(unsigned int irq) { return 0; }
51 static void ack_none(unsigned int irq)
54 * 'what should we do if we get a hw irq event on an illegal vector'.
55 * each architecture has to answer this themself.
60 struct hw_interrupt_type no_irq_type = {
62 .startup = startup_none,
63 .shutdown = shutdown_none,
64 .enable = enable_none,
65 .disable = disable_none,
72 * Special, empty irq handler:
74 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
80 * handle_IRQ_event - irq action chain handler
81 * @irq: the interrupt number
82 * @regs: pointer to a register structure
83 * @action: the interrupt action chain for this irq
85 * Handles the action chain of an irq event
87 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
88 struct irqaction *action)
90 irqreturn_t ret, retval = IRQ_NONE;
91 unsigned int status = 0;
93 if (!(action->flags & SA_INTERRUPT))
97 ret = action->handler(irq, action->dev_id, regs);
98 if (ret == IRQ_HANDLED)
99 status |= action->flags;
101 action = action->next;
104 if (status & SA_SAMPLE_RANDOM)
105 add_interrupt_randomness(irq);
112 * __do_IRQ - original all in one highlevel IRQ handler
113 * @irq: the interrupt number
114 * @regs: pointer to a register structure
116 * __do_IRQ handles all normal device IRQ's (the special
117 * SMP cross-CPU interrupts have their own specific
120 * This is the original x86 implementation which is used for every
123 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
125 struct irq_desc *desc = irq_desc + irq;
126 struct irqaction *action;
129 kstat_this_cpu.irqs[irq]++;
130 if (CHECK_IRQ_PER_CPU(desc->status)) {
131 irqreturn_t action_ret;
134 * No locking required for CPU-local interrupts:
137 desc->chip->ack(irq);
138 action_ret = handle_IRQ_event(irq, regs, desc->action);
139 desc->chip->end(irq);
143 spin_lock(&desc->lock);
145 desc->chip->ack(irq);
147 * REPLAY is when Linux resends an IRQ that was dropped earlier
148 * WAITING is used by probe to mark irqs that are being tested
150 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
151 status |= IRQ_PENDING; /* we _want_ to handle it */
154 * If the IRQ is disabled for whatever reason, we cannot
155 * use the action we have.
158 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
159 action = desc->action;
160 status &= ~IRQ_PENDING; /* we commit to handling */
161 status |= IRQ_INPROGRESS; /* we are handling it */
163 desc->status = status;
166 * If there is no IRQ handler or it was disabled, exit early.
167 * Since we set PENDING, if another processor is handling
168 * a different instance of this same irq, the other processor
169 * will take care of it.
171 if (unlikely(!action))
175 * Edge triggered interrupts need to remember
177 * This applies to any hw interrupts that allow a second
178 * instance of the same irq to arrive while we are in do_IRQ
179 * or in the handler. But the code here only handles the _second_
180 * instance of the irq, not the third or fourth. So it is mostly
181 * useful for irq hardware that does not mask cleanly in an
185 irqreturn_t action_ret;
187 spin_unlock(&desc->lock);
189 action_ret = handle_IRQ_event(irq, regs, action);
191 spin_lock(&desc->lock);
193 note_interrupt(irq, desc, action_ret, regs);
194 if (likely(!(desc->status & IRQ_PENDING)))
196 desc->status &= ~IRQ_PENDING;
198 desc->status &= ~IRQ_INPROGRESS;
202 * The ->end() handler has to deal with interrupts which got
203 * disabled while the handler was running.
205 desc->chip->end(irq);
206 spin_unlock(&desc->lock);