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 * Have got an event to handle:
78 fastcall
int handle_IRQ_event(unsigned int irq
, struct pt_regs
*regs
,
79 struct irqaction
*action
)
81 int ret
, retval
= 0, status
= 0;
83 if (!(action
->flags
& SA_INTERRUPT
))
87 ret
= action
->handler(irq
, action
->dev_id
, regs
);
88 if (ret
== IRQ_HANDLED
)
89 status
|= action
->flags
;
91 action
= action
->next
;
94 if (status
& SA_SAMPLE_RANDOM
)
95 add_interrupt_randomness(irq
);
102 * do_IRQ handles all normal device IRQ's (the special
103 * SMP cross-CPU interrupts have their own specific
106 fastcall
unsigned int __do_IRQ(unsigned int irq
, struct pt_regs
*regs
)
108 irq_desc_t
*desc
= irq_desc
+ irq
;
109 struct irqaction
* action
;
112 kstat_this_cpu
.irqs
[irq
]++;
113 if (desc
->status
& IRQ_PER_CPU
) {
114 irqreturn_t action_ret
;
117 * No locking required for CPU-local interrupts:
119 desc
->handler
->ack(irq
);
120 action_ret
= handle_IRQ_event(irq
, regs
, desc
->action
);
122 note_interrupt(irq
, desc
, action_ret
);
123 desc
->handler
->end(irq
);
127 spin_lock(&desc
->lock
);
128 desc
->handler
->ack(irq
);
130 * REPLAY is when Linux resends an IRQ that was dropped earlier
131 * WAITING is used by probe to mark irqs that are being tested
133 status
= desc
->status
& ~(IRQ_REPLAY
| IRQ_WAITING
);
134 status
|= IRQ_PENDING
; /* we _want_ to handle it */
137 * If the IRQ is disabled for whatever reason, we cannot
138 * use the action we have.
141 if (likely(!(status
& (IRQ_DISABLED
| IRQ_INPROGRESS
)))) {
142 action
= desc
->action
;
143 status
&= ~IRQ_PENDING
; /* we commit to handling */
144 status
|= IRQ_INPROGRESS
; /* we are handling it */
146 desc
->status
= status
;
149 * If there is no IRQ handler or it was disabled, exit early.
150 * Since we set PENDING, if another processor is handling
151 * a different instance of this same irq, the other processor
152 * will take care of it.
154 if (unlikely(!action
))
158 * Edge triggered interrupts need to remember
160 * This applies to any hw interrupts that allow a second
161 * instance of the same irq to arrive while we are in do_IRQ
162 * or in the handler. But the code here only handles the _second_
163 * instance of the irq, not the third or fourth. So it is mostly
164 * useful for irq hardware that does not mask cleanly in an
168 irqreturn_t action_ret
;
170 spin_unlock(&desc
->lock
);
172 action_ret
= handle_IRQ_event(irq
, regs
, action
);
174 spin_lock(&desc
->lock
);
176 note_interrupt(irq
, desc
, action_ret
);
177 if (likely(!(desc
->status
& IRQ_PENDING
)))
179 desc
->status
&= ~IRQ_PENDING
;
181 desc
->status
&= ~IRQ_INPROGRESS
;
185 * The ->end() handler has to deal with interrupts which got
186 * disabled while the handler was running.
188 desc
->handler
->end(irq
);
189 spin_unlock(&desc
->lock
);