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1da177e4 LT |
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 | ||
b77d6adc | 9 | #include <linux/config.h> |
1da177e4 LT |
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 | /** | |
22 | * synchronize_irq - wait for pending IRQ handlers (on other CPUs) | |
23 | * | |
24 | * This function waits for any pending IRQ handlers for this interrupt | |
25 | * to complete before returning. If you use this function while | |
26 | * holding a resource the IRQ handler may need you will deadlock. | |
27 | * | |
28 | * This function may be called - with care - from IRQ context. | |
29 | */ | |
30 | void synchronize_irq(unsigned int irq) | |
31 | { | |
32 | struct irq_desc *desc = irq_desc + irq; | |
33 | ||
34 | while (desc->status & IRQ_INPROGRESS) | |
35 | cpu_relax(); | |
36 | } | |
37 | ||
38 | EXPORT_SYMBOL(synchronize_irq); | |
39 | ||
40 | #endif | |
41 | ||
42 | /** | |
43 | * disable_irq_nosync - disable an irq without waiting | |
44 | * @irq: Interrupt to disable | |
45 | * | |
46 | * Disable the selected interrupt line. Disables and Enables are | |
47 | * nested. | |
48 | * Unlike disable_irq(), this function does not ensure existing | |
49 | * instances of the IRQ handler have completed before returning. | |
50 | * | |
51 | * This function may be called from IRQ context. | |
52 | */ | |
53 | void disable_irq_nosync(unsigned int irq) | |
54 | { | |
55 | irq_desc_t *desc = irq_desc + irq; | |
56 | unsigned long flags; | |
57 | ||
58 | spin_lock_irqsave(&desc->lock, flags); | |
59 | if (!desc->depth++) { | |
60 | desc->status |= IRQ_DISABLED; | |
61 | desc->handler->disable(irq); | |
62 | } | |
63 | spin_unlock_irqrestore(&desc->lock, flags); | |
64 | } | |
65 | ||
66 | EXPORT_SYMBOL(disable_irq_nosync); | |
67 | ||
68 | /** | |
69 | * disable_irq - disable an irq and wait for completion | |
70 | * @irq: Interrupt to disable | |
71 | * | |
72 | * Disable the selected interrupt line. Enables and Disables are | |
73 | * nested. | |
74 | * This function waits for any pending IRQ handlers for this interrupt | |
75 | * to complete before returning. If you use this function while | |
76 | * holding a resource the IRQ handler may need you will deadlock. | |
77 | * | |
78 | * This function may be called - with care - from IRQ context. | |
79 | */ | |
80 | void disable_irq(unsigned int irq) | |
81 | { | |
82 | irq_desc_t *desc = irq_desc + irq; | |
83 | ||
84 | disable_irq_nosync(irq); | |
85 | if (desc->action) | |
86 | synchronize_irq(irq); | |
87 | } | |
88 | ||
89 | EXPORT_SYMBOL(disable_irq); | |
90 | ||
91 | /** | |
92 | * enable_irq - enable handling of an irq | |
93 | * @irq: Interrupt to enable | |
94 | * | |
95 | * Undoes the effect of one call to disable_irq(). If this | |
96 | * matches the last disable, processing of interrupts on this | |
97 | * IRQ line is re-enabled. | |
98 | * | |
99 | * This function may be called from IRQ context. | |
100 | */ | |
101 | void enable_irq(unsigned int irq) | |
102 | { | |
103 | irq_desc_t *desc = irq_desc + irq; | |
104 | unsigned long flags; | |
105 | ||
106 | spin_lock_irqsave(&desc->lock, flags); | |
107 | switch (desc->depth) { | |
108 | case 0: | |
109 | WARN_ON(1); | |
110 | break; | |
111 | case 1: { | |
112 | unsigned int status = desc->status & ~IRQ_DISABLED; | |
113 | ||
114 | desc->status = status; | |
115 | if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) { | |
116 | desc->status = status | IRQ_REPLAY; | |
117 | hw_resend_irq(desc->handler,irq); | |
118 | } | |
119 | desc->handler->enable(irq); | |
120 | /* fall-through */ | |
121 | } | |
122 | default: | |
123 | desc->depth--; | |
124 | } | |
125 | spin_unlock_irqrestore(&desc->lock, flags); | |
126 | } | |
127 | ||
128 | EXPORT_SYMBOL(enable_irq); | |
129 | ||
130 | /* | |
131 | * Internal function that tells the architecture code whether a | |
132 | * particular irq has been exclusively allocated or is available | |
133 | * for driver use. | |
134 | */ | |
135 | int can_request_irq(unsigned int irq, unsigned long irqflags) | |
136 | { | |
137 | struct irqaction *action; | |
138 | ||
139 | if (irq >= NR_IRQS) | |
140 | return 0; | |
141 | ||
142 | action = irq_desc[irq].action; | |
143 | if (action) | |
144 | if (irqflags & action->flags & SA_SHIRQ) | |
145 | action = NULL; | |
146 | ||
147 | return !action; | |
148 | } | |
149 | ||
150 | /* | |
151 | * Internal function to register an irqaction - typically used to | |
152 | * allocate special interrupts that are part of the architecture. | |
153 | */ | |
154 | int setup_irq(unsigned int irq, struct irqaction * new) | |
155 | { | |
156 | struct irq_desc *desc = irq_desc + irq; | |
157 | struct irqaction *old, **p; | |
158 | unsigned long flags; | |
159 | int shared = 0; | |
160 | ||
161 | if (desc->handler == &no_irq_type) | |
162 | return -ENOSYS; | |
163 | /* | |
164 | * Some drivers like serial.c use request_irq() heavily, | |
165 | * so we have to be careful not to interfere with a | |
166 | * running system. | |
167 | */ | |
168 | if (new->flags & SA_SAMPLE_RANDOM) { | |
169 | /* | |
170 | * This function might sleep, we want to call it first, | |
171 | * outside of the atomic block. | |
172 | * Yes, this might clear the entropy pool if the wrong | |
173 | * driver is attempted to be loaded, without actually | |
174 | * installing a new handler, but is this really a problem, | |
175 | * only the sysadmin is able to do this. | |
176 | */ | |
177 | rand_initialize_irq(irq); | |
178 | } | |
179 | ||
180 | /* | |
181 | * The following block of code has to be executed atomically | |
182 | */ | |
183 | spin_lock_irqsave(&desc->lock,flags); | |
184 | p = &desc->action; | |
185 | if ((old = *p) != NULL) { | |
186 | /* Can't share interrupts unless both agree to */ | |
187 | if (!(old->flags & new->flags & SA_SHIRQ)) { | |
188 | spin_unlock_irqrestore(&desc->lock,flags); | |
189 | return -EBUSY; | |
190 | } | |
191 | ||
192 | /* add new interrupt at end of irq queue */ | |
193 | do { | |
194 | p = &old->next; | |
195 | old = *p; | |
196 | } while (old); | |
197 | shared = 1; | |
198 | } | |
199 | ||
200 | *p = new; | |
201 | ||
202 | if (!shared) { | |
203 | desc->depth = 0; | |
204 | desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | | |
205 | IRQ_WAITING | IRQ_INPROGRESS); | |
206 | if (desc->handler->startup) | |
207 | desc->handler->startup(irq); | |
208 | else | |
209 | desc->handler->enable(irq); | |
210 | } | |
211 | spin_unlock_irqrestore(&desc->lock,flags); | |
212 | ||
213 | new->irq = irq; | |
214 | register_irq_proc(irq); | |
215 | new->dir = NULL; | |
216 | register_handler_proc(irq, new); | |
217 | ||
218 | return 0; | |
219 | } | |
220 | ||
221 | /** | |
222 | * free_irq - free an interrupt | |
223 | * @irq: Interrupt line to free | |
224 | * @dev_id: Device identity to free | |
225 | * | |
226 | * Remove an interrupt handler. The handler is removed and if the | |
227 | * interrupt line is no longer in use by any driver it is disabled. | |
228 | * On a shared IRQ the caller must ensure the interrupt is disabled | |
229 | * on the card it drives before calling this function. The function | |
230 | * does not return until any executing interrupts for this IRQ | |
231 | * have completed. | |
232 | * | |
233 | * This function must not be called from interrupt context. | |
234 | */ | |
235 | void free_irq(unsigned int irq, void *dev_id) | |
236 | { | |
237 | struct irq_desc *desc; | |
238 | struct irqaction **p; | |
239 | unsigned long flags; | |
240 | ||
241 | if (irq >= NR_IRQS) | |
242 | return; | |
243 | ||
244 | desc = irq_desc + irq; | |
245 | spin_lock_irqsave(&desc->lock,flags); | |
246 | p = &desc->action; | |
247 | for (;;) { | |
248 | struct irqaction * action = *p; | |
249 | ||
250 | if (action) { | |
251 | struct irqaction **pp = p; | |
252 | ||
253 | p = &action->next; | |
254 | if (action->dev_id != dev_id) | |
255 | continue; | |
256 | ||
257 | /* Found it - now remove it from the list of entries */ | |
258 | *pp = action->next; | |
dbce706e | 259 | |
b77d6adc PBG |
260 | /* Currently used only by UML, might disappear one day.*/ |
261 | #ifdef CONFIG_IRQ_RELEASE_METHOD | |
dbce706e PBG |
262 | if (desc->handler->release) |
263 | desc->handler->release(irq, dev_id); | |
b77d6adc | 264 | #endif |
dbce706e | 265 | |
1da177e4 LT |
266 | if (!desc->action) { |
267 | desc->status |= IRQ_DISABLED; | |
268 | if (desc->handler->shutdown) | |
269 | desc->handler->shutdown(irq); | |
270 | else | |
271 | desc->handler->disable(irq); | |
272 | } | |
273 | spin_unlock_irqrestore(&desc->lock,flags); | |
274 | unregister_handler_proc(irq, action); | |
275 | ||
276 | /* Make sure it's not being used on another CPU */ | |
277 | synchronize_irq(irq); | |
278 | kfree(action); | |
279 | return; | |
280 | } | |
281 | printk(KERN_ERR "Trying to free free IRQ%d\n",irq); | |
282 | spin_unlock_irqrestore(&desc->lock,flags); | |
283 | return; | |
284 | } | |
285 | } | |
286 | ||
287 | EXPORT_SYMBOL(free_irq); | |
288 | ||
289 | /** | |
290 | * request_irq - allocate an interrupt line | |
291 | * @irq: Interrupt line to allocate | |
292 | * @handler: Function to be called when the IRQ occurs | |
293 | * @irqflags: Interrupt type flags | |
294 | * @devname: An ascii name for the claiming device | |
295 | * @dev_id: A cookie passed back to the handler function | |
296 | * | |
297 | * This call allocates interrupt resources and enables the | |
298 | * interrupt line and IRQ handling. From the point this | |
299 | * call is made your handler function may be invoked. Since | |
300 | * your handler function must clear any interrupt the board | |
301 | * raises, you must take care both to initialise your hardware | |
302 | * and to set up the interrupt handler in the right order. | |
303 | * | |
304 | * Dev_id must be globally unique. Normally the address of the | |
305 | * device data structure is used as the cookie. Since the handler | |
306 | * receives this value it makes sense to use it. | |
307 | * | |
308 | * If your interrupt is shared you must pass a non NULL dev_id | |
309 | * as this is required when freeing the interrupt. | |
310 | * | |
311 | * Flags: | |
312 | * | |
313 | * SA_SHIRQ Interrupt is shared | |
314 | * SA_INTERRUPT Disable local interrupts while processing | |
315 | * SA_SAMPLE_RANDOM The interrupt can be used for entropy | |
316 | * | |
317 | */ | |
318 | int request_irq(unsigned int irq, | |
319 | irqreturn_t (*handler)(int, void *, struct pt_regs *), | |
320 | unsigned long irqflags, const char * devname, void *dev_id) | |
321 | { | |
322 | struct irqaction * action; | |
323 | int retval; | |
324 | ||
325 | /* | |
326 | * Sanity-check: shared interrupts must pass in a real dev-ID, | |
327 | * otherwise we'll have trouble later trying to figure out | |
328 | * which interrupt is which (messes up the interrupt freeing | |
329 | * logic etc). | |
330 | */ | |
331 | if ((irqflags & SA_SHIRQ) && !dev_id) | |
332 | return -EINVAL; | |
333 | if (irq >= NR_IRQS) | |
334 | return -EINVAL; | |
335 | if (!handler) | |
336 | return -EINVAL; | |
337 | ||
338 | action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC); | |
339 | if (!action) | |
340 | return -ENOMEM; | |
341 | ||
342 | action->handler = handler; | |
343 | action->flags = irqflags; | |
344 | cpus_clear(action->mask); | |
345 | action->name = devname; | |
346 | action->next = NULL; | |
347 | action->dev_id = dev_id; | |
348 | ||
349 | retval = setup_irq(irq, action); | |
350 | if (retval) | |
351 | kfree(action); | |
352 | ||
353 | return retval; | |
354 | } | |
355 | ||
356 | EXPORT_SYMBOL(request_irq); | |
357 |