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1 | /* | |
2 | * linux/kernel/irq/manage.c | |
3 | * | |
4 | * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar | |
5 | * | |
6 | * This file contains driver APIs to the irq subsystem. | |
7 | */ | |
8 | ||
9 | #include <linux/config.h> | |
10 | #include <linux/irq.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/random.h> | |
13 | #include <linux/interrupt.h> | |
14 | ||
15 | #include "internals.h" | |
16 | ||
17 | #ifdef CONFIG_SMP | |
18 | ||
19 | cpumask_t irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL }; | |
20 | ||
21 | #if defined (CONFIG_GENERIC_PENDING_IRQ) || defined (CONFIG_IRQBALANCE) | |
22 | cpumask_t __cacheline_aligned pending_irq_cpumask[NR_IRQS]; | |
23 | #endif | |
24 | ||
25 | /** | |
26 | * synchronize_irq - wait for pending IRQ handlers (on other CPUs) | |
27 | * | |
28 | * This function waits for any pending IRQ handlers for this interrupt | |
29 | * to complete before returning. If you use this function while | |
30 | * holding a resource the IRQ handler may need you will deadlock. | |
31 | * | |
32 | * This function may be called - with care - from IRQ context. | |
33 | */ | |
34 | void synchronize_irq(unsigned int irq) | |
35 | { | |
36 | struct irq_desc *desc = irq_desc + irq; | |
37 | ||
38 | while (desc->status & IRQ_INPROGRESS) | |
39 | cpu_relax(); | |
40 | } | |
41 | ||
42 | EXPORT_SYMBOL(synchronize_irq); | |
43 | ||
44 | #endif | |
45 | ||
46 | /** | |
47 | * disable_irq_nosync - disable an irq without waiting | |
48 | * @irq: Interrupt to disable | |
49 | * | |
50 | * Disable the selected interrupt line. Disables and Enables are | |
51 | * nested. | |
52 | * Unlike disable_irq(), this function does not ensure existing | |
53 | * instances of the IRQ handler have completed before returning. | |
54 | * | |
55 | * This function may be called from IRQ context. | |
56 | */ | |
57 | void disable_irq_nosync(unsigned int irq) | |
58 | { | |
59 | irq_desc_t *desc = irq_desc + irq; | |
60 | unsigned long flags; | |
61 | ||
62 | spin_lock_irqsave(&desc->lock, flags); | |
63 | if (!desc->depth++) { | |
64 | desc->status |= IRQ_DISABLED; | |
65 | desc->handler->disable(irq); | |
66 | } | |
67 | spin_unlock_irqrestore(&desc->lock, flags); | |
68 | } | |
69 | ||
70 | EXPORT_SYMBOL(disable_irq_nosync); | |
71 | ||
72 | /** | |
73 | * disable_irq - disable an irq and wait for completion | |
74 | * @irq: Interrupt to disable | |
75 | * | |
76 | * Disable the selected interrupt line. Enables and Disables are | |
77 | * nested. | |
78 | * This function waits for any pending IRQ handlers for this interrupt | |
79 | * to complete before returning. If you use this function while | |
80 | * holding a resource the IRQ handler may need you will deadlock. | |
81 | * | |
82 | * This function may be called - with care - from IRQ context. | |
83 | */ | |
84 | void disable_irq(unsigned int irq) | |
85 | { | |
86 | irq_desc_t *desc = irq_desc + irq; | |
87 | ||
88 | disable_irq_nosync(irq); | |
89 | if (desc->action) | |
90 | synchronize_irq(irq); | |
91 | } | |
92 | ||
93 | EXPORT_SYMBOL(disable_irq); | |
94 | ||
95 | /** | |
96 | * enable_irq - enable handling of an irq | |
97 | * @irq: Interrupt to enable | |
98 | * | |
99 | * Undoes the effect of one call to disable_irq(). If this | |
100 | * matches the last disable, processing of interrupts on this | |
101 | * IRQ line is re-enabled. | |
102 | * | |
103 | * This function may be called from IRQ context. | |
104 | */ | |
105 | void enable_irq(unsigned int irq) | |
106 | { | |
107 | irq_desc_t *desc = irq_desc + irq; | |
108 | unsigned long flags; | |
109 | ||
110 | spin_lock_irqsave(&desc->lock, flags); | |
111 | switch (desc->depth) { | |
112 | case 0: | |
113 | WARN_ON(1); | |
114 | break; | |
115 | case 1: { | |
116 | unsigned int status = desc->status & ~IRQ_DISABLED; | |
117 | ||
118 | desc->status = status; | |
119 | if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) { | |
120 | desc->status = status | IRQ_REPLAY; | |
121 | hw_resend_irq(desc->handler,irq); | |
122 | } | |
123 | desc->handler->enable(irq); | |
124 | /* fall-through */ | |
125 | } | |
126 | default: | |
127 | desc->depth--; | |
128 | } | |
129 | spin_unlock_irqrestore(&desc->lock, flags); | |
130 | } | |
131 | ||
132 | EXPORT_SYMBOL(enable_irq); | |
133 | ||
134 | /* | |
135 | * Internal function that tells the architecture code whether a | |
136 | * particular irq has been exclusively allocated or is available | |
137 | * for driver use. | |
138 | */ | |
139 | int can_request_irq(unsigned int irq, unsigned long irqflags) | |
140 | { | |
141 | struct irqaction *action; | |
142 | ||
143 | if (irq >= NR_IRQS) | |
144 | return 0; | |
145 | ||
146 | action = irq_desc[irq].action; | |
147 | if (action) | |
148 | if (irqflags & action->flags & SA_SHIRQ) | |
149 | action = NULL; | |
150 | ||
151 | return !action; | |
152 | } | |
153 | ||
154 | /* | |
155 | * Internal function to register an irqaction - typically used to | |
156 | * allocate special interrupts that are part of the architecture. | |
157 | */ | |
158 | int setup_irq(unsigned int irq, struct irqaction * new) | |
159 | { | |
160 | struct irq_desc *desc = irq_desc + irq; | |
161 | struct irqaction *old, **p; | |
162 | unsigned long flags; | |
163 | int shared = 0; | |
164 | ||
165 | if (desc->handler == &no_irq_type) | |
166 | return -ENOSYS; | |
167 | /* | |
168 | * Some drivers like serial.c use request_irq() heavily, | |
169 | * so we have to be careful not to interfere with a | |
170 | * running system. | |
171 | */ | |
172 | if (new->flags & SA_SAMPLE_RANDOM) { | |
173 | /* | |
174 | * This function might sleep, we want to call it first, | |
175 | * outside of the atomic block. | |
176 | * Yes, this might clear the entropy pool if the wrong | |
177 | * driver is attempted to be loaded, without actually | |
178 | * installing a new handler, but is this really a problem, | |
179 | * only the sysadmin is able to do this. | |
180 | */ | |
181 | rand_initialize_irq(irq); | |
182 | } | |
183 | ||
184 | /* | |
185 | * The following block of code has to be executed atomically | |
186 | */ | |
187 | spin_lock_irqsave(&desc->lock,flags); | |
188 | p = &desc->action; | |
189 | if ((old = *p) != NULL) { | |
190 | /* Can't share interrupts unless both agree to */ | |
191 | if (!(old->flags & new->flags & SA_SHIRQ)) { | |
192 | spin_unlock_irqrestore(&desc->lock,flags); | |
193 | return -EBUSY; | |
194 | } | |
195 | ||
196 | /* add new interrupt at end of irq queue */ | |
197 | do { | |
198 | p = &old->next; | |
199 | old = *p; | |
200 | } while (old); | |
201 | shared = 1; | |
202 | } | |
203 | ||
204 | *p = new; | |
205 | ||
206 | if (!shared) { | |
207 | desc->depth = 0; | |
208 | desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | | |
209 | IRQ_WAITING | IRQ_INPROGRESS); | |
210 | if (desc->handler->startup) | |
211 | desc->handler->startup(irq); | |
212 | else | |
213 | desc->handler->enable(irq); | |
214 | } | |
215 | spin_unlock_irqrestore(&desc->lock,flags); | |
216 | ||
217 | new->irq = irq; | |
218 | register_irq_proc(irq); | |
219 | new->dir = NULL; | |
220 | register_handler_proc(irq, new); | |
221 | ||
222 | return 0; | |
223 | } | |
224 | ||
225 | /** | |
226 | * free_irq - free an interrupt | |
227 | * @irq: Interrupt line to free | |
228 | * @dev_id: Device identity to free | |
229 | * | |
230 | * Remove an interrupt handler. The handler is removed and if the | |
231 | * interrupt line is no longer in use by any driver it is disabled. | |
232 | * On a shared IRQ the caller must ensure the interrupt is disabled | |
233 | * on the card it drives before calling this function. The function | |
234 | * does not return until any executing interrupts for this IRQ | |
235 | * have completed. | |
236 | * | |
237 | * This function must not be called from interrupt context. | |
238 | */ | |
239 | void free_irq(unsigned int irq, void *dev_id) | |
240 | { | |
241 | struct irq_desc *desc; | |
242 | struct irqaction **p; | |
243 | unsigned long flags; | |
244 | ||
245 | if (irq >= NR_IRQS) | |
246 | return; | |
247 | ||
248 | desc = irq_desc + irq; | |
249 | spin_lock_irqsave(&desc->lock,flags); | |
250 | p = &desc->action; | |
251 | for (;;) { | |
252 | struct irqaction * action = *p; | |
253 | ||
254 | if (action) { | |
255 | struct irqaction **pp = p; | |
256 | ||
257 | p = &action->next; | |
258 | if (action->dev_id != dev_id) | |
259 | continue; | |
260 | ||
261 | /* Found it - now remove it from the list of entries */ | |
262 | *pp = action->next; | |
263 | ||
264 | /* Currently used only by UML, might disappear one day.*/ | |
265 | #ifdef CONFIG_IRQ_RELEASE_METHOD | |
266 | if (desc->handler->release) | |
267 | desc->handler->release(irq, dev_id); | |
268 | #endif | |
269 | ||
270 | if (!desc->action) { | |
271 | desc->status |= IRQ_DISABLED; | |
272 | if (desc->handler->shutdown) | |
273 | desc->handler->shutdown(irq); | |
274 | else | |
275 | desc->handler->disable(irq); | |
276 | } | |
277 | spin_unlock_irqrestore(&desc->lock,flags); | |
278 | unregister_handler_proc(irq, action); | |
279 | ||
280 | /* Make sure it's not being used on another CPU */ | |
281 | synchronize_irq(irq); | |
282 | kfree(action); | |
283 | return; | |
284 | } | |
285 | printk(KERN_ERR "Trying to free free IRQ%d\n",irq); | |
286 | spin_unlock_irqrestore(&desc->lock,flags); | |
287 | return; | |
288 | } | |
289 | } | |
290 | ||
291 | EXPORT_SYMBOL(free_irq); | |
292 | ||
293 | /** | |
294 | * request_irq - allocate an interrupt line | |
295 | * @irq: Interrupt line to allocate | |
296 | * @handler: Function to be called when the IRQ occurs | |
297 | * @irqflags: Interrupt type flags | |
298 | * @devname: An ascii name for the claiming device | |
299 | * @dev_id: A cookie passed back to the handler function | |
300 | * | |
301 | * This call allocates interrupt resources and enables the | |
302 | * interrupt line and IRQ handling. From the point this | |
303 | * call is made your handler function may be invoked. Since | |
304 | * your handler function must clear any interrupt the board | |
305 | * raises, you must take care both to initialise your hardware | |
306 | * and to set up the interrupt handler in the right order. | |
307 | * | |
308 | * Dev_id must be globally unique. Normally the address of the | |
309 | * device data structure is used as the cookie. Since the handler | |
310 | * receives this value it makes sense to use it. | |
311 | * | |
312 | * If your interrupt is shared you must pass a non NULL dev_id | |
313 | * as this is required when freeing the interrupt. | |
314 | * | |
315 | * Flags: | |
316 | * | |
317 | * SA_SHIRQ Interrupt is shared | |
318 | * SA_INTERRUPT Disable local interrupts while processing | |
319 | * SA_SAMPLE_RANDOM The interrupt can be used for entropy | |
320 | * | |
321 | */ | |
322 | int request_irq(unsigned int irq, | |
323 | irqreturn_t (*handler)(int, void *, struct pt_regs *), | |
324 | unsigned long irqflags, const char * devname, void *dev_id) | |
325 | { | |
326 | struct irqaction * action; | |
327 | int retval; | |
328 | ||
329 | /* | |
330 | * Sanity-check: shared interrupts must pass in a real dev-ID, | |
331 | * otherwise we'll have trouble later trying to figure out | |
332 | * which interrupt is which (messes up the interrupt freeing | |
333 | * logic etc). | |
334 | */ | |
335 | if ((irqflags & SA_SHIRQ) && !dev_id) | |
336 | return -EINVAL; | |
337 | if (irq >= NR_IRQS) | |
338 | return -EINVAL; | |
339 | if (!handler) | |
340 | return -EINVAL; | |
341 | ||
342 | action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC); | |
343 | if (!action) | |
344 | return -ENOMEM; | |
345 | ||
346 | action->handler = handler; | |
347 | action->flags = irqflags; | |
348 | cpus_clear(action->mask); | |
349 | action->name = devname; | |
350 | action->next = NULL; | |
351 | action->dev_id = dev_id; | |
352 | ||
353 | retval = setup_irq(irq, action); | |
354 | if (retval) | |
355 | kfree(action); | |
356 | ||
357 | return retval; | |
358 | } | |
359 | ||
360 | EXPORT_SYMBOL(request_irq); | |
361 |