2 * linux/kernel/irq/manage.c
4 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
6 * This file contains driver APIs to the irq subsystem.
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>
15 #include "internals.h"
20 * synchronize_irq - wait for pending IRQ handlers (on other CPUs)
21 * @irq: interrupt number to wait for
23 * This function waits for any pending IRQ handlers for this interrupt
24 * to complete before returning. If you use this function while
25 * holding a resource the IRQ handler may need you will deadlock.
27 * This function may be called - with care - from IRQ context.
29 void synchronize_irq(unsigned int irq)
31 struct irq_desc *desc = irq_desc + irq;
36 while (desc->status & IRQ_INPROGRESS)
39 EXPORT_SYMBOL(synchronize_irq);
44 * disable_irq_nosync - disable an irq without waiting
45 * @irq: Interrupt to disable
47 * Disable the selected interrupt line. Disables and Enables are
49 * Unlike disable_irq(), this function does not ensure existing
50 * instances of the IRQ handler have completed before returning.
52 * This function may be called from IRQ context.
54 void disable_irq_nosync(unsigned int irq)
56 struct irq_desc *desc = irq_desc + irq;
62 spin_lock_irqsave(&desc->lock, flags);
64 desc->status |= IRQ_DISABLED;
65 desc->chip->disable(irq);
67 spin_unlock_irqrestore(&desc->lock, flags);
69 EXPORT_SYMBOL(disable_irq_nosync);
72 * disable_irq - disable an irq and wait for completion
73 * @irq: Interrupt to disable
75 * Disable the selected interrupt line. Enables and Disables are
77 * This function waits for any pending IRQ handlers for this interrupt
78 * to complete before returning. If you use this function while
79 * holding a resource the IRQ handler may need you will deadlock.
81 * This function may be called - with care - from IRQ context.
83 void disable_irq(unsigned int irq)
85 struct irq_desc *desc = irq_desc + irq;
90 disable_irq_nosync(irq);
94 EXPORT_SYMBOL(disable_irq);
97 * enable_irq - enable handling of an irq
98 * @irq: Interrupt to enable
100 * Undoes the effect of one call to disable_irq(). If this
101 * matches the last disable, processing of interrupts on this
102 * IRQ line is re-enabled.
104 * This function may be called from IRQ context.
106 void enable_irq(unsigned int irq)
108 struct irq_desc *desc = irq_desc + irq;
114 spin_lock_irqsave(&desc->lock, flags);
115 switch (desc->depth) {
120 unsigned int status = desc->status & ~IRQ_DISABLED;
122 desc->status = status;
123 if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
124 desc->status = status | IRQ_REPLAY;
125 hw_resend_irq(desc->chip,irq);
127 desc->chip->enable(irq);
133 spin_unlock_irqrestore(&desc->lock, flags);
135 EXPORT_SYMBOL(enable_irq);
138 * Internal function that tells the architecture code whether a
139 * particular irq has been exclusively allocated or is available
142 int can_request_irq(unsigned int irq, unsigned long irqflags)
144 struct irqaction *action;
149 action = irq_desc[irq].action;
151 if (irqflags & action->flags & SA_SHIRQ)
158 * Internal function to register an irqaction - typically used to
159 * allocate special interrupts that are part of the architecture.
161 int setup_irq(unsigned int irq, struct irqaction *new)
163 struct irq_desc *desc = irq_desc + irq;
164 struct irqaction *old, **p;
171 if (desc->chip == &no_irq_type)
174 * Some drivers like serial.c use request_irq() heavily,
175 * so we have to be careful not to interfere with a
178 if (new->flags & SA_SAMPLE_RANDOM) {
180 * This function might sleep, we want to call it first,
181 * outside of the atomic block.
182 * Yes, this might clear the entropy pool if the wrong
183 * driver is attempted to be loaded, without actually
184 * installing a new handler, but is this really a problem,
185 * only the sysadmin is able to do this.
187 rand_initialize_irq(irq);
191 * The following block of code has to be executed atomically
193 spin_lock_irqsave(&desc->lock, flags);
197 /* Can't share interrupts unless both agree to */
198 if (!(old->flags & new->flags & SA_SHIRQ))
201 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
202 /* All handlers must agree on per-cpuness */
203 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
207 /* add new interrupt at end of irq queue */
216 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
217 if (new->flags & SA_PERCPU_IRQ)
218 desc->status |= IRQ_PER_CPU;
222 desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT |
223 IRQ_WAITING | IRQ_INPROGRESS);
224 if (desc->chip->startup)
225 desc->chip->startup(irq);
227 desc->chip->enable(irq);
229 spin_unlock_irqrestore(&desc->lock, flags);
232 register_irq_proc(irq);
234 register_handler_proc(irq, new);
239 spin_unlock_irqrestore(&desc->lock, flags);
240 if (!(new->flags & SA_PROBEIRQ)) {
241 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
248 * free_irq - free an interrupt
249 * @irq: Interrupt line to free
250 * @dev_id: Device identity to free
252 * Remove an interrupt handler. The handler is removed and if the
253 * interrupt line is no longer in use by any driver it is disabled.
254 * On a shared IRQ the caller must ensure the interrupt is disabled
255 * on the card it drives before calling this function. The function
256 * does not return until any executing interrupts for this IRQ
259 * This function must not be called from interrupt context.
261 void free_irq(unsigned int irq, void *dev_id)
263 struct irq_desc *desc;
264 struct irqaction **p;
267 WARN_ON(in_interrupt());
271 desc = irq_desc + irq;
272 spin_lock_irqsave(&desc->lock, flags);
275 struct irqaction *action = *p;
278 struct irqaction **pp = p;
281 if (action->dev_id != dev_id)
284 /* Found it - now remove it from the list of entries */
287 /* Currently used only by UML, might disappear one day.*/
288 #ifdef CONFIG_IRQ_RELEASE_METHOD
289 if (desc->chip->release)
290 desc->chip->release(irq, dev_id);
294 desc->status |= IRQ_DISABLED;
295 if (desc->chip->shutdown)
296 desc->chip->shutdown(irq);
298 desc->chip->disable(irq);
300 spin_unlock_irqrestore(&desc->lock, flags);
301 unregister_handler_proc(irq, action);
303 /* Make sure it's not being used on another CPU */
304 synchronize_irq(irq);
308 printk(KERN_ERR "Trying to free free IRQ%d\n", irq);
309 spin_unlock_irqrestore(&desc->lock, flags);
313 EXPORT_SYMBOL(free_irq);
316 * request_irq - allocate an interrupt line
317 * @irq: Interrupt line to allocate
318 * @handler: Function to be called when the IRQ occurs
319 * @irqflags: Interrupt type flags
320 * @devname: An ascii name for the claiming device
321 * @dev_id: A cookie passed back to the handler function
323 * This call allocates interrupt resources and enables the
324 * interrupt line and IRQ handling. From the point this
325 * call is made your handler function may be invoked. Since
326 * your handler function must clear any interrupt the board
327 * raises, you must take care both to initialise your hardware
328 * and to set up the interrupt handler in the right order.
330 * Dev_id must be globally unique. Normally the address of the
331 * device data structure is used as the cookie. Since the handler
332 * receives this value it makes sense to use it.
334 * If your interrupt is shared you must pass a non NULL dev_id
335 * as this is required when freeing the interrupt.
339 * SA_SHIRQ Interrupt is shared
340 * SA_INTERRUPT Disable local interrupts while processing
341 * SA_SAMPLE_RANDOM The interrupt can be used for entropy
344 int request_irq(unsigned int irq,
345 irqreturn_t (*handler)(int, void *, struct pt_regs *),
346 unsigned long irqflags, const char *devname, void *dev_id)
348 struct irqaction *action;
352 * Sanity-check: shared interrupts must pass in a real dev-ID,
353 * otherwise we'll have trouble later trying to figure out
354 * which interrupt is which (messes up the interrupt freeing
357 if ((irqflags & SA_SHIRQ) && !dev_id)
364 action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
368 action->handler = handler;
369 action->flags = irqflags;
370 cpus_clear(action->mask);
371 action->name = devname;
373 action->dev_id = dev_id;
375 select_smp_affinity(irq);
377 retval = setup_irq(irq, action);
383 EXPORT_SYMBOL(request_irq);