2 * linux/kernel/irq/manage.c
4 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
5 * Copyright (C) 2005-2006 Thomas Gleixner
7 * This file contains driver APIs to the irq subsystem.
10 #include <linux/config.h>
11 #include <linux/irq.h>
12 #include <linux/module.h>
13 #include <linux/random.h>
14 #include <linux/interrupt.h>
16 #include "internals.h"
21 * synchronize_irq - wait for pending IRQ handlers (on other CPUs)
22 * @irq: interrupt number to wait for
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.
28 * This function may be called - with care - from IRQ context.
30 void synchronize_irq(unsigned int irq)
32 struct irq_desc *desc = irq_desc + irq;
37 while (desc->status & IRQ_INPROGRESS)
40 EXPORT_SYMBOL(synchronize_irq);
45 * disable_irq_nosync - disable an irq without waiting
46 * @irq: Interrupt to disable
48 * Disable the selected interrupt line. Disables and Enables are
50 * Unlike disable_irq(), this function does not ensure existing
51 * instances of the IRQ handler have completed before returning.
53 * This function may be called from IRQ context.
55 void disable_irq_nosync(unsigned int irq)
57 struct irq_desc *desc = irq_desc + irq;
63 spin_lock_irqsave(&desc->lock, flags);
65 desc->status |= IRQ_DISABLED;
66 desc->chip->disable(irq);
68 spin_unlock_irqrestore(&desc->lock, flags);
70 EXPORT_SYMBOL(disable_irq_nosync);
73 * disable_irq - disable an irq and wait for completion
74 * @irq: Interrupt to disable
76 * Disable the selected interrupt line. Enables and Disables are
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.
82 * This function may be called - with care - from IRQ context.
84 void disable_irq(unsigned int irq)
86 struct irq_desc *desc = irq_desc + irq;
91 disable_irq_nosync(irq);
95 EXPORT_SYMBOL(disable_irq);
98 * enable_irq - enable handling of an irq
99 * @irq: Interrupt to enable
101 * Undoes the effect of one call to disable_irq(). If this
102 * matches the last disable, processing of interrupts on this
103 * IRQ line is re-enabled.
105 * This function may be called from IRQ context.
107 void enable_irq(unsigned int irq)
109 struct irq_desc *desc = irq_desc + irq;
115 spin_lock_irqsave(&desc->lock, flags);
116 switch (desc->depth) {
118 printk(KERN_WARNING "Unablanced enable_irq(%d)\n", irq);
122 unsigned int status = desc->status & ~IRQ_DISABLED;
124 /* Prevent probing on this irq: */
125 desc->status = status | IRQ_NOPROBE;
126 check_irq_resend(desc, irq);
132 spin_unlock_irqrestore(&desc->lock, flags);
134 EXPORT_SYMBOL(enable_irq);
137 * Internal function that tells the architecture code whether a
138 * particular irq has been exclusively allocated or is available
141 int can_request_irq(unsigned int irq, unsigned long irqflags)
143 struct irqaction *action;
145 if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
148 action = irq_desc[irq].action;
150 if (irqflags & action->flags & SA_SHIRQ)
157 * Internal function to register an irqaction - typically used to
158 * allocate special interrupts that are part of the architecture.
160 int setup_irq(unsigned int irq, struct irqaction *new)
162 struct irq_desc *desc = irq_desc + irq;
163 struct irqaction *old, **p;
170 if (desc->chip == &no_irq_type)
173 * Some drivers like serial.c use request_irq() heavily,
174 * so we have to be careful not to interfere with a
177 if (new->flags & SA_SAMPLE_RANDOM) {
179 * This function might sleep, we want to call it first,
180 * outside of the atomic block.
181 * Yes, this might clear the entropy pool if the wrong
182 * driver is attempted to be loaded, without actually
183 * installing a new handler, but is this really a problem,
184 * only the sysadmin is able to do this.
186 rand_initialize_irq(irq);
190 * The following block of code has to be executed atomically
192 spin_lock_irqsave(&desc->lock, flags);
196 /* Can't share interrupts unless both agree to */
197 if (!(old->flags & new->flags & SA_SHIRQ))
200 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
201 /* All handlers must agree on per-cpuness */
202 if ((old->flags & IRQ_PER_CPU) != (new->flags & IRQ_PER_CPU))
206 /* add new interrupt at end of irq queue */
215 #if defined(CONFIG_IRQ_PER_CPU) && defined(SA_PERCPU_IRQ)
216 if (new->flags & SA_PERCPU_IRQ)
217 desc->status |= IRQ_PER_CPU;
220 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
223 if (!(desc->status & IRQ_NOAUTOEN)) {
225 desc->status &= ~IRQ_DISABLED;
226 if (desc->chip->startup)
227 desc->chip->startup(irq);
229 desc->chip->enable(irq);
232 spin_unlock_irqrestore(&desc->lock, flags);
235 register_irq_proc(irq);
237 register_handler_proc(irq, new);
242 spin_unlock_irqrestore(&desc->lock, flags);
243 if (!(new->flags & SA_PROBEIRQ)) {
244 printk(KERN_ERR "%s: irq handler mismatch\n", __FUNCTION__);
251 * free_irq - free an interrupt
252 * @irq: Interrupt line to free
253 * @dev_id: Device identity to free
255 * Remove an interrupt handler. The handler is removed and if the
256 * interrupt line is no longer in use by any driver it is disabled.
257 * On a shared IRQ the caller must ensure the interrupt is disabled
258 * on the card it drives before calling this function. The function
259 * does not return until any executing interrupts for this IRQ
262 * This function must not be called from interrupt context.
264 void free_irq(unsigned int irq, void *dev_id)
266 struct irq_desc *desc;
267 struct irqaction **p;
270 WARN_ON(in_interrupt());
274 desc = irq_desc + irq;
275 spin_lock_irqsave(&desc->lock, flags);
278 struct irqaction *action = *p;
281 struct irqaction **pp = p;
284 if (action->dev_id != dev_id)
287 /* Found it - now remove it from the list of entries */
290 /* Currently used only by UML, might disappear one day.*/
291 #ifdef CONFIG_IRQ_RELEASE_METHOD
292 if (desc->chip->release)
293 desc->chip->release(irq, dev_id);
297 desc->status |= IRQ_DISABLED;
298 if (desc->chip->shutdown)
299 desc->chip->shutdown(irq);
301 desc->chip->disable(irq);
303 spin_unlock_irqrestore(&desc->lock, flags);
304 unregister_handler_proc(irq, action);
306 /* Make sure it's not being used on another CPU */
307 synchronize_irq(irq);
311 printk(KERN_ERR "Trying to free free IRQ%d\n", irq);
312 spin_unlock_irqrestore(&desc->lock, flags);
316 EXPORT_SYMBOL(free_irq);
319 * request_irq - allocate an interrupt line
320 * @irq: Interrupt line to allocate
321 * @handler: Function to be called when the IRQ occurs
322 * @irqflags: Interrupt type flags
323 * @devname: An ascii name for the claiming device
324 * @dev_id: A cookie passed back to the handler function
326 * This call allocates interrupt resources and enables the
327 * interrupt line and IRQ handling. From the point this
328 * call is made your handler function may be invoked. Since
329 * your handler function must clear any interrupt the board
330 * raises, you must take care both to initialise your hardware
331 * and to set up the interrupt handler in the right order.
333 * Dev_id must be globally unique. Normally the address of the
334 * device data structure is used as the cookie. Since the handler
335 * receives this value it makes sense to use it.
337 * If your interrupt is shared you must pass a non NULL dev_id
338 * as this is required when freeing the interrupt.
342 * SA_SHIRQ Interrupt is shared
343 * SA_INTERRUPT Disable local interrupts while processing
344 * SA_SAMPLE_RANDOM The interrupt can be used for entropy
347 int request_irq(unsigned int irq,
348 irqreturn_t (*handler)(int, void *, struct pt_regs *),
349 unsigned long irqflags, const char *devname, void *dev_id)
351 struct irqaction *action;
355 * Sanity-check: shared interrupts must pass in a real dev-ID,
356 * otherwise we'll have trouble later trying to figure out
357 * which interrupt is which (messes up the interrupt freeing
360 if ((irqflags & SA_SHIRQ) && !dev_id)
364 if (irq_desc[irq].status & IRQ_NOREQUEST)
369 action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
373 action->handler = handler;
374 action->flags = irqflags;
375 cpus_clear(action->mask);
376 action->name = devname;
378 action->dev_id = dev_id;
380 select_smp_affinity(irq);
382 retval = setup_irq(irq, action);
388 EXPORT_SYMBOL(request_irq);