ia64/linux-2.6.18-xen.hg

view kernel/irq/handle.c @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents 831230e53067
children
line source
1 /*
2 * linux/kernel/irq/handle.c
3 *
4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
6 *
7 * This file contains the core interrupt handling code.
8 *
9 * Detailed information is available in Documentation/DocBook/genericirq
10 *
11 */
13 #include <linux/irq.h>
14 #include <linux/module.h>
15 #include <linux/random.h>
16 #include <linux/interrupt.h>
17 #include <linux/kernel_stat.h>
19 #include "internals.h"
21 /**
22 * handle_bad_irq - handle spurious and unhandled irqs
23 * @irq: the interrupt number
24 * @desc: description of the interrupt
25 * @regs: pointer to a register structure
26 *
27 * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
28 */
29 void fastcall
30 handle_bad_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
31 {
32 print_irq_desc(irq, desc);
33 kstat_this_cpu.irqs[irq]++;
34 ack_bad_irq(irq);
35 }
37 /*
38 * Linux has a controller-independent interrupt architecture.
39 * Every controller has a 'controller-template', that is used
40 * by the main code to do the right thing. Each driver-visible
41 * interrupt source is transparently wired to the appropriate
42 * controller. Thus drivers need not be aware of the
43 * interrupt-controller.
44 *
45 * The code is designed to be easily extended with new/different
46 * interrupt controllers, without having to do assembly magic or
47 * having to touch the generic code.
48 *
49 * Controller mappings for all interrupt sources:
50 */
51 struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned = {
52 [0 ... NR_IRQS-1] = {
53 .status = IRQ_DISABLED,
54 .chip = &no_irq_chip,
55 .handle_irq = handle_bad_irq,
56 .depth = 1,
57 .lock = SPIN_LOCK_UNLOCKED,
58 #ifdef CONFIG_SMP
59 .affinity = CPU_MASK_ALL
60 #endif
61 }
62 };
64 /*
65 * What should we do if we get a hw irq event on an illegal vector?
66 * Each architecture has to answer this themself.
67 */
68 static void ack_bad(unsigned int irq)
69 {
70 print_irq_desc(irq, irq_desc + irq);
71 ack_bad_irq(irq);
72 }
74 /*
75 * NOP functions
76 */
77 static void noop(unsigned int irq)
78 {
79 }
81 static unsigned int noop_ret(unsigned int irq)
82 {
83 return 0;
84 }
86 /*
87 * Generic no controller implementation
88 */
89 struct irq_chip no_irq_chip = {
90 .name = "none",
91 .startup = noop_ret,
92 .shutdown = noop,
93 .enable = noop,
94 .disable = noop,
95 .ack = ack_bad,
96 .end = noop,
97 };
99 /*
100 * Generic dummy implementation which can be used for
101 * real dumb interrupt sources
102 */
103 struct irq_chip dummy_irq_chip = {
104 .name = "dummy",
105 .startup = noop_ret,
106 .shutdown = noop,
107 .enable = noop,
108 .disable = noop,
109 .ack = noop,
110 .mask = noop,
111 .unmask = noop,
112 .end = noop,
113 };
115 /*
116 * Special, empty irq handler:
117 */
118 irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
119 {
120 return IRQ_NONE;
121 }
123 /**
124 * handle_IRQ_event - irq action chain handler
125 * @irq: the interrupt number
126 * @regs: pointer to a register structure
127 * @action: the interrupt action chain for this irq
128 *
129 * Handles the action chain of an irq event
130 */
131 irqreturn_t handle_IRQ_event(unsigned int irq, struct pt_regs *regs,
132 struct irqaction *action)
133 {
134 irqreturn_t ret, retval = IRQ_NONE;
135 unsigned int status = 0;
137 handle_dynamic_tick(action);
139 if (!(action->flags & IRQF_DISABLED))
140 local_irq_enable_in_hardirq();
142 do {
143 ret = action->handler(irq, action->dev_id, regs);
144 if (ret == IRQ_HANDLED)
145 status |= action->flags;
146 retval |= ret;
147 action = action->next;
148 } while (action);
150 if (status & IRQF_SAMPLE_RANDOM)
151 add_interrupt_randomness(irq);
152 local_irq_disable();
154 return retval;
155 }
157 /**
158 * __do_IRQ - original all in one highlevel IRQ handler
159 * @irq: the interrupt number
160 * @regs: pointer to a register structure
161 *
162 * __do_IRQ handles all normal device IRQ's (the special
163 * SMP cross-CPU interrupts have their own specific
164 * handlers).
165 *
166 * This is the original x86 implementation which is used for every
167 * interrupt type.
168 */
169 fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs)
170 {
171 struct irq_desc *desc = irq_desc + irq;
172 struct irqaction *action;
173 unsigned int status;
175 kstat_this_cpu.irqs[irq]++;
176 if (CHECK_IRQ_PER_CPU(desc->status)) {
177 irqreturn_t action_ret;
179 /*
180 * No locking required for CPU-local interrupts:
181 */
182 if (desc->chip->ack)
183 desc->chip->ack(irq);
184 action_ret = handle_IRQ_event(irq, regs, desc->action);
185 desc->chip->end(irq);
186 return 1;
187 }
189 spin_lock(&desc->lock);
190 if (desc->chip->ack)
191 desc->chip->ack(irq);
192 /*
193 * REPLAY is when Linux resends an IRQ that was dropped earlier
194 * WAITING is used by probe to mark irqs that are being tested
195 */
196 status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
197 status |= IRQ_PENDING; /* we _want_ to handle it */
199 /*
200 * If the IRQ is disabled for whatever reason, we cannot
201 * use the action we have.
202 */
203 action = NULL;
204 if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
205 action = desc->action;
206 status &= ~IRQ_PENDING; /* we commit to handling */
207 status |= IRQ_INPROGRESS; /* we are handling it */
208 }
209 desc->status = status;
211 /*
212 * If there is no IRQ handler or it was disabled, exit early.
213 * Since we set PENDING, if another processor is handling
214 * a different instance of this same irq, the other processor
215 * will take care of it.
216 */
217 if (unlikely(!action))
218 goto out;
220 /*
221 * Edge triggered interrupts need to remember
222 * pending events.
223 * This applies to any hw interrupts that allow a second
224 * instance of the same irq to arrive while we are in do_IRQ
225 * or in the handler. But the code here only handles the _second_
226 * instance of the irq, not the third or fourth. So it is mostly
227 * useful for irq hardware that does not mask cleanly in an
228 * SMP environment.
229 */
230 for (;;) {
231 irqreturn_t action_ret;
233 spin_unlock(&desc->lock);
235 action_ret = handle_IRQ_event(irq, regs, action);
237 spin_lock(&desc->lock);
238 if (!noirqdebug)
239 note_interrupt(irq, desc, action_ret, regs);
240 if (likely(!(desc->status & IRQ_PENDING)))
241 break;
242 desc->status &= ~IRQ_PENDING;
243 }
244 desc->status &= ~IRQ_INPROGRESS;
246 out:
247 /*
248 * The ->end() handler has to deal with interrupts which got
249 * disabled while the handler was running.
250 */
251 desc->chip->end(irq);
252 spin_unlock(&desc->lock);
254 return 1;
255 }
257 #ifdef CONFIG_TRACE_IRQFLAGS
259 /*
260 * lockdep: we want to handle all irq_desc locks as a single lock-class:
261 */
262 static struct lock_class_key irq_desc_lock_class;
264 void early_init_irq_lock_class(void)
265 {
266 int i;
268 for (i = 0; i < NR_IRQS; i++)
269 lockdep_set_class(&irq_desc[i].lock, &irq_desc_lock_class);
270 }
272 #endif