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) {
117 printk(KERN_WARNING "Unablanced enable_irq(%d)\n", irq);
121 unsigned int status = desc->status & ~IRQ_DISABLED;
123 desc->status = status;
124 if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
125 desc->status = status | IRQ_REPLAY;
126 if (desc->chip && desc->chip->retrigger)
127 desc->chip->retrigger(irq);
129 desc->chip->enable(irq);
135 spin_unlock_irqrestore(&desc->lock, flags);
137 EXPORT_SYMBOL(enable_irq);
140 * Internal function that tells the architecture code whether a
141 * particular irq has been exclusively allocated or is available
144 int can_request_irq(unsigned int irq, unsigned long irqflags)
146 struct irqaction *action;
151 action = irq_desc[irq].action;
153 if (irqflags & action->flags & SA_SHIRQ)
160 * Internal function to register an irqaction - typically used to
161 * allocate special interrupts that are part of the architecture.
163 int setup_irq(unsigned int irq, struct irqaction *new)
165 struct irq_desc *desc = irq_desc + irq;
166 struct irqaction *old, **p;
173 if (desc->chip == &no_irq_type)
176 * Some drivers like serial.c use request_irq() heavily,
177 * so we have to be careful not to interfere with a
180 if (new->flags & SA_SAMPLE_RANDOM) {
182 * This function might sleep, we want to call it first,
183 * outside of the atomic block.
184 * Yes, this might clear the entropy pool if the wrong
185 * driver is attempted to be loaded, without actually
186 * installing a new handler, but is this really a problem,
187 * only the sysadmin is able to do this.
189 rand_initialize_irq(irq);
193 * The following block of code has to be executed atomically
195 spin_lock_irqsave(&desc->lock, flags);
199 /* Can't share interrupts unless both agree to */
200 if (!(old->flags & new->flags & SA_SHIRQ))
203 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
204 /* All handlers must agree on per-cpuness */
205 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
209 /* add new interrupt at end of irq queue */
218 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
219 if (new->flags & SA_PERCPU_IRQ)
220 desc->status |= IRQ_PER_CPU;
224 desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT |
225 IRQ_WAITING | IRQ_INPROGRESS);
226 if (desc->chip->startup)
227 desc->chip->startup(irq);
229 desc->chip->enable(irq);
231 spin_unlock_irqrestore(&desc->lock, flags);
234 register_irq_proc(irq);
236 register_handler_proc(irq, new);
241 spin_unlock_irqrestore(&desc->lock, flags);
242 if (!(new->flags & SA_PROBEIRQ)) {
243 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
250 * free_irq - free an interrupt
251 * @irq: Interrupt line to free
252 * @dev_id: Device identity to free
254 * Remove an interrupt handler. The handler is removed and if the
255 * interrupt line is no longer in use by any driver it is disabled.
256 * On a shared IRQ the caller must ensure the interrupt is disabled
257 * on the card it drives before calling this function. The function
258 * does not return until any executing interrupts for this IRQ
261 * This function must not be called from interrupt context.
263 void free_irq(unsigned int irq, void *dev_id)
265 struct irq_desc *desc;
266 struct irqaction **p;
269 WARN_ON(in_interrupt());
273 desc = irq_desc + irq;
274 spin_lock_irqsave(&desc->lock, flags);
277 struct irqaction *action = *p;
280 struct irqaction **pp = p;
283 if (action->dev_id != dev_id)
286 /* Found it - now remove it from the list of entries */
289 /* Currently used only by UML, might disappear one day.*/
290 #ifdef CONFIG_IRQ_RELEASE_METHOD
291 if (desc->chip->release)
292 desc->chip->release(irq, dev_id);
296 desc->status |= IRQ_DISABLED;
297 if (desc->chip->shutdown)
298 desc->chip->shutdown(irq);
300 desc->chip->disable(irq);
302 spin_unlock_irqrestore(&desc->lock, flags);
303 unregister_handler_proc(irq, action);
305 /* Make sure it's not being used on another CPU */
306 synchronize_irq(irq);
310 printk(KERN_ERR "Trying to free free IRQ%d\n", irq);
311 spin_unlock_irqrestore(&desc->lock, flags);
315 EXPORT_SYMBOL(free_irq);
318 * request_irq - allocate an interrupt line
319 * @irq: Interrupt line to allocate
320 * @handler: Function to be called when the IRQ occurs
321 * @irqflags: Interrupt type flags
322 * @devname: An ascii name for the claiming device
323 * @dev_id: A cookie passed back to the handler function
325 * This call allocates interrupt resources and enables the
326 * interrupt line and IRQ handling. From the point this
327 * call is made your handler function may be invoked. Since
328 * your handler function must clear any interrupt the board
329 * raises, you must take care both to initialise your hardware
330 * and to set up the interrupt handler in the right order.
332 * Dev_id must be globally unique. Normally the address of the
333 * device data structure is used as the cookie. Since the handler
334 * receives this value it makes sense to use it.
336 * If your interrupt is shared you must pass a non NULL dev_id
337 * as this is required when freeing the interrupt.
341 * SA_SHIRQ Interrupt is shared
342 * SA_INTERRUPT Disable local interrupts while processing
343 * SA_SAMPLE_RANDOM The interrupt can be used for entropy
346 int request_irq(unsigned int irq,
347 irqreturn_t (*handler)(int, void *, struct pt_regs *),
348 unsigned long irqflags, const char *devname, void *dev_id)
350 struct irqaction *action;
354 * Sanity-check: shared interrupts must pass in a real dev-ID,
355 * otherwise we'll have trouble later trying to figure out
356 * which interrupt is which (messes up the interrupt freeing
359 if ((irqflags & SA_SHIRQ) && !dev_id)
366 action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
370 action->handler = handler;
371 action->flags = irqflags;
372 cpus_clear(action->mask);
373 action->name = devname;
375 action->dev_id = dev_id;
377 select_smp_affinity(irq);
379 retval = setup_irq(irq, action);
385 EXPORT_SYMBOL(request_irq);