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1da177e4 LT |
1 | /* |
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 | |
21 | * interrupt source is transparently wired to the apropriate | |
22 | * 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 | */ | |
31 | irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = { | |
32 | [0 ... NR_IRQS-1] = { | |
33 | .handler = &no_irq_type, | |
34 | .lock = SPIN_LOCK_UNLOCKED | |
35 | } | |
36 | }; | |
37 | ||
38 | /* | |
39 | * Generic 'no controller' code | |
40 | */ | |
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; } | |
46 | ||
47 | static void ack_none(unsigned int irq) | |
48 | { | |
49 | /* | |
50 | * 'what should we do if we get a hw irq event on an illegal vector'. | |
51 | * each architecture has to answer this themself. | |
52 | */ | |
53 | ack_bad_irq(irq); | |
54 | } | |
55 | ||
56 | struct hw_interrupt_type no_irq_type = { | |
57 | .typename = "none", | |
58 | .startup = startup_none, | |
59 | .shutdown = shutdown_none, | |
60 | .enable = enable_none, | |
61 | .disable = disable_none, | |
62 | .ack = ack_none, | |
63 | .end = end_none, | |
64 | .set_affinity = NULL | |
65 | }; | |
66 | ||
67 | /* | |
68 | * Special, empty irq handler: | |
69 | */ | |
70 | irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs) | |
71 | { | |
72 | return IRQ_NONE; | |
73 | } | |
74 | ||
75 | /* | |
76 | * Have got an event to handle: | |
77 | */ | |
78 | fastcall int handle_IRQ_event(unsigned int irq, struct pt_regs *regs, | |
79 | struct irqaction *action) | |
80 | { | |
81 | int ret, retval = 0, status = 0; | |
82 | ||
83 | if (!(action->flags & SA_INTERRUPT)) | |
84 | local_irq_enable(); | |
85 | ||
86 | do { | |
87 | ret = action->handler(irq, action->dev_id, regs); | |
88 | if (ret == IRQ_HANDLED) | |
89 | status |= action->flags; | |
90 | retval |= ret; | |
91 | action = action->next; | |
92 | } while (action); | |
93 | ||
94 | if (status & SA_SAMPLE_RANDOM) | |
95 | add_interrupt_randomness(irq); | |
96 | local_irq_disable(); | |
97 | ||
98 | return retval; | |
99 | } | |
100 | ||
101 | /* | |
102 | * do_IRQ handles all normal device IRQ's (the special | |
103 | * SMP cross-CPU interrupts have their own specific | |
104 | * handlers). | |
105 | */ | |
106 | fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs) | |
107 | { | |
108 | irq_desc_t *desc = irq_desc + irq; | |
109 | struct irqaction * action; | |
110 | unsigned int status; | |
111 | ||
112 | kstat_this_cpu.irqs[irq]++; | |
113 | if (desc->status & IRQ_PER_CPU) { | |
114 | irqreturn_t action_ret; | |
115 | ||
116 | /* | |
117 | * No locking required for CPU-local interrupts: | |
118 | */ | |
119 | desc->handler->ack(irq); | |
120 | action_ret = handle_IRQ_event(irq, regs, desc->action); | |
121 | if (!noirqdebug) | |
122 | note_interrupt(irq, desc, action_ret); | |
123 | desc->handler->end(irq); | |
124 | return 1; | |
125 | } | |
126 | ||
127 | spin_lock(&desc->lock); | |
128 | desc->handler->ack(irq); | |
129 | /* | |
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 | |
132 | */ | |
133 | status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING); | |
134 | status |= IRQ_PENDING; /* we _want_ to handle it */ | |
135 | ||
136 | /* | |
137 | * If the IRQ is disabled for whatever reason, we cannot | |
138 | * use the action we have. | |
139 | */ | |
140 | action = NULL; | |
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 */ | |
145 | } | |
146 | desc->status = status; | |
147 | ||
148 | /* | |
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. | |
153 | */ | |
154 | if (unlikely(!action)) | |
155 | goto out; | |
156 | ||
157 | /* | |
158 | * Edge triggered interrupts need to remember | |
159 | * pending events. | |
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 | |
165 | * SMP environment. | |
166 | */ | |
167 | for (;;) { | |
168 | irqreturn_t action_ret; | |
169 | ||
170 | spin_unlock(&desc->lock); | |
171 | ||
172 | action_ret = handle_IRQ_event(irq, regs, action); | |
173 | ||
174 | spin_lock(&desc->lock); | |
175 | if (!noirqdebug) | |
176 | note_interrupt(irq, desc, action_ret); | |
177 | if (likely(!(desc->status & IRQ_PENDING))) | |
178 | break; | |
179 | desc->status &= ~IRQ_PENDING; | |
180 | } | |
181 | desc->status &= ~IRQ_INPROGRESS; | |
182 | ||
183 | out: | |
184 | /* | |
185 | * The ->end() handler has to deal with interrupts which got | |
186 | * disabled while the handler was running. | |
187 | */ | |
188 | desc->handler->end(irq); | |
189 | spin_unlock(&desc->lock); | |
190 | ||
191 | return 1; | |
192 | } | |
193 |