kernel/irq/manage.c - linux - Git at Google

 /*
  * linux/kernel/irq/manage.c
  *
  * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
  *
  * This file contains driver APIs to the irq subsystem.
  */

 #include <linux/config.h>
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/random.h>
 #include <linux/interrupt.h>

 #include "internals.h"

 #ifdef CONFIG_SMP

 cpumask_t irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };

 /**
  *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  *
  *	This function waits for any pending IRQ handlers for this interrupt
  *	to complete before returning. If you use this function while
  *	holding a resource the IRQ handler may need you will deadlock.
  *
  *	This function may be called - with care - from IRQ context.
  */
 void synchronize_irq(unsigned int irq)
 {
 	struct irq_desc *desc = irq_desc + irq;

 	while (desc->status & IRQ_INPROGRESS)
 		cpu_relax();
 }

 EXPORT_SYMBOL(synchronize_irq);

 #endif

 /**
  *	disable_irq_nosync - disable an irq without waiting
  *	@irq: Interrupt to disable
  *
  *	Disable the selected interrupt line.  Disables and Enables are
  *	nested.
  *	Unlike disable_irq(), this function does not ensure existing
  *	instances of the IRQ handler have completed before returning.
  *
  *	This function may be called from IRQ context.
  */
 void disable_irq_nosync(unsigned int irq)
 {
 	irq_desc_t *desc = irq_desc + irq;
 	unsigned long flags;

 	spin_lock_irqsave(&desc->lock, flags);
 	if (!desc->depth++) {
 		desc->status |= IRQ_DISABLED;
 		desc->handler->disable(irq);
 	}
 	spin_unlock_irqrestore(&desc->lock, flags);
 }

 EXPORT_SYMBOL(disable_irq_nosync);

 /**
  *	disable_irq - disable an irq and wait for completion
  *	@irq: Interrupt to disable
  *
  *	Disable the selected interrupt line.  Enables and Disables are
  *	nested.
  *	This function waits for any pending IRQ handlers for this interrupt
  *	to complete before returning. If you use this function while
  *	holding a resource the IRQ handler may need you will deadlock.
  *
  *	This function may be called - with care - from IRQ context.
  */
 void disable_irq(unsigned int irq)
 {
 	irq_desc_t *desc = irq_desc + irq;

 	disable_irq_nosync(irq);
 	if (desc->action)
 		synchronize_irq(irq);
 }

 EXPORT_SYMBOL(disable_irq);

 /**
  *	enable_irq - enable handling of an irq
  *	@irq: Interrupt to enable
  *
  *	Undoes the effect of one call to disable_irq().  If this
  *	matches the last disable, processing of interrupts on this
  *	IRQ line is re-enabled.
  *
  *	This function may be called from IRQ context.
  */
 void enable_irq(unsigned int irq)
 {
 	irq_desc_t *desc = irq_desc + irq;
 	unsigned long flags;

 	spin_lock_irqsave(&desc->lock, flags);
 	switch (desc->depth) {
 	case 0:
 		WARN_ON(1);
 		break;
 	case 1: {
 		unsigned int status = desc->status & ~IRQ_DISABLED;

 		desc->status = status;
 		if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
 			desc->status = status | IRQ_REPLAY;
 			hw_resend_irq(desc->handler,irq);
 		}
 		desc->handler->enable(irq);
 		/* fall-through */
 	}
 	default:
 		desc->depth--;
 	}
 	spin_unlock_irqrestore(&desc->lock, flags);
 }

 EXPORT_SYMBOL(enable_irq);

 /*
  * Internal function that tells the architecture code whether a
  * particular irq has been exclusively allocated or is available
  * for driver use.
  */
 int can_request_irq(unsigned int irq, unsigned long irqflags)
 {
 	struct irqaction *action;

 	if (irq >= NR_IRQS)
 		return 0;

 	action = irq_desc[irq].action;
 	if (action)
 		if (irqflags & action->flags & SA_SHIRQ)
 			action = NULL;

 	return !action;
 }

 /*
  * Internal function to register an irqaction - typically used to
  * allocate special interrupts that are part of the architecture.
  */
 int setup_irq(unsigned int irq, struct irqaction * new)
 {
 	struct irq_desc *desc = irq_desc + irq;
 	struct irqaction *old, **p;
 	unsigned long flags;
 	int shared = 0;

 	if (desc->handler == &no_irq_type)
 		return -ENOSYS;
 	/*
 	 * Some drivers like serial.c use request_irq() heavily,
 	 * so we have to be careful not to interfere with a
 	 * running system.
 	 */
 	if (new->flags & SA_SAMPLE_RANDOM) {
 		/*
 		 * This function might sleep, we want to call it first,
 		 * outside of the atomic block.
 		 * Yes, this might clear the entropy pool if the wrong
 		 * driver is attempted to be loaded, without actually
 		 * installing a new handler, but is this really a problem,
 		 * only the sysadmin is able to do this.
 		 */
 		rand_initialize_irq(irq);
 	}

 	/*
 	 * The following block of code has to be executed atomically
 	 */
 	spin_lock_irqsave(&desc->lock,flags);
 	p = &desc->action;
 	if ((old = *p) != NULL) {
 		/* Can't share interrupts unless both agree to */
 		if (!(old->flags & new->flags & SA_SHIRQ)) {
 			spin_unlock_irqrestore(&desc->lock,flags);
 			return -EBUSY;
 		}

 		/* add new interrupt at end of irq queue */
 		do {
 			p = &old->next;
 			old = *p;
 		} while (old);
 		shared = 1;
 	}

 	*p = new;

 	if (!shared) {
 		desc->depth = 0;
 		desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT |
 				  IRQ_WAITING | IRQ_INPROGRESS);
 		if (desc->handler->startup)
 			desc->handler->startup(irq);
 		else
 			desc->handler->enable(irq);
 	}
 	spin_unlock_irqrestore(&desc->lock,flags);

 	new->irq = irq;
 	register_irq_proc(irq);
 	new->dir = NULL;
 	register_handler_proc(irq, new);

 	return 0;
 }

 /**
  *	free_irq - free an interrupt
  *	@irq: Interrupt line to free
  *	@dev_id: Device identity to free
  *
  *	Remove an interrupt handler. The handler is removed and if the
  *	interrupt line is no longer in use by any driver it is disabled.
  *	On a shared IRQ the caller must ensure the interrupt is disabled
  *	on the card it drives before calling this function. The function
  *	does not return until any executing interrupts for this IRQ
  *	have completed.
  *
  *	This function must not be called from interrupt context.
  */
 void free_irq(unsigned int irq, void *dev_id)
 {
 	struct irq_desc *desc;
 	struct irqaction **p;
 	unsigned long flags;

 	if (irq >= NR_IRQS)
 		return;

 	desc = irq_desc + irq;
 	spin_lock_irqsave(&desc->lock,flags);
 	p = &desc->action;
 	for (;;) {
 		struct irqaction * action = *p;

 		if (action) {
 			struct irqaction **pp = p;

 			p = &action->next;
 			if (action->dev_id != dev_id)
 				continue;

 			/* Found it - now remove it from the list of entries */
 			*pp = action->next;

 			/* Currently used only by UML, might disappear one day.*/
 #ifdef CONFIG_IRQ_RELEASE_METHOD
 			if (desc->handler->release)
 				desc->handler->release(irq, dev_id);
 #endif

 			if (!desc->action) {
 				desc->status |= IRQ_DISABLED;
 				if (desc->handler->shutdown)
 					desc->handler->shutdown(irq);
 				else
 					desc->handler->disable(irq);
 			}
 			spin_unlock_irqrestore(&desc->lock,flags);
 			unregister_handler_proc(irq, action);

 			/* Make sure it's not being used on another CPU */
 			synchronize_irq(irq);
 			kfree(action);
 			return;
 		}
 		printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
 		spin_unlock_irqrestore(&desc->lock,flags);
 		return;
 	}
 }

 EXPORT_SYMBOL(free_irq);

 /**
  *	request_irq - allocate an interrupt line
  *	@irq: Interrupt line to allocate
  *	@handler: Function to be called when the IRQ occurs
  *	@irqflags: Interrupt type flags
  *	@devname: An ascii name for the claiming device
  *	@dev_id: A cookie passed back to the handler function
  *
  *	This call allocates interrupt resources and enables the
  *	interrupt line and IRQ handling. From the point this
  *	call is made your handler function may be invoked. Since
  *	your handler function must clear any interrupt the board
  *	raises, you must take care both to initialise your hardware
  *	and to set up the interrupt handler in the right order.
  *
  *	Dev_id must be globally unique. Normally the address of the
  *	device data structure is used as the cookie. Since the handler
  *	receives this value it makes sense to use it.
  *
  *	If your interrupt is shared you must pass a non NULL dev_id
  *	as this is required when freeing the interrupt.
  *
  *	Flags:
  *
  *	SA_SHIRQ		Interrupt is shared
  *	SA_INTERRUPT		Disable local interrupts while processing
  *	SA_SAMPLE_RANDOM	The interrupt can be used for entropy
  *
  */
 int request_irq(unsigned int irq,
 		irqreturn_t (*handler)(int, void *, struct pt_regs *),
 		unsigned long irqflags, const char * devname, void *dev_id)
 {
 	struct irqaction * action;
 	int retval;

 	/*
 	 * Sanity-check: shared interrupts must pass in a real dev-ID,
 	 * otherwise we'll have trouble later trying to figure out
 	 * which interrupt is which (messes up the interrupt freeing
 	 * logic etc).
 	 */
 	if ((irqflags & SA_SHIRQ) && !dev_id)
 		return -EINVAL;
 	if (irq >= NR_IRQS)
 		return -EINVAL;
 	if (!handler)
 		return -EINVAL;

 	action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 	if (!action)
 		return -ENOMEM;

 	action->handler = handler;
 	action->flags = irqflags;
 	cpus_clear(action->mask);
 	action->name = devname;
 	action->next = NULL;
 	action->dev_id = dev_id;

 	retval = setup_irq(irq, action);
 	if (retval)
 		kfree(action);

 	return retval;
 }

 EXPORT_SYMBOL(request_irq);
	/*
	* linux/kernel/irq/manage.c
	*
	* Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
	*
	* This file contains driver APIs to the irq subsystem.
	*/

	#include <linux/config.h>
	#include <linux/irq.h>
	#include <linux/module.h>
	#include <linux/random.h>
	#include <linux/interrupt.h>

	#include "internals.h"

	#ifdef CONFIG_SMP

	cpumask_t irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };

	/**
	* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
	*
	* This function waits for any pending IRQ handlers for this interrupt
	* to complete before returning. If you use this function while
	* holding a resource the IRQ handler may need you will deadlock.
	*
	* This function may be called - with care - from IRQ context.
	*/
	void synchronize_irq(unsigned int irq)
	{
	struct irq_desc *desc = irq_desc + irq;

	while (desc->status & IRQ_INPROGRESS)
	cpu_relax();
	}

	EXPORT_SYMBOL(synchronize_irq);

	#endif

	/**
	* disable_irq_nosync - disable an irq without waiting
	* @irq: Interrupt to disable
	*
	* Disable the selected interrupt line. Disables and Enables are
	* nested.
	* Unlike disable_irq(), this function does not ensure existing
	* instances of the IRQ handler have completed before returning.
	*
	* This function may be called from IRQ context.
	*/
	void disable_irq_nosync(unsigned int irq)
	{
	irq_desc_t *desc = irq_desc + irq;
	unsigned long flags;

	spin_lock_irqsave(&desc->lock, flags);
	if (!desc->depth++) {
	desc->status \|= IRQ_DISABLED;
	desc->handler->disable(irq);
	}
	spin_unlock_irqrestore(&desc->lock, flags);
	}

	EXPORT_SYMBOL(disable_irq_nosync);

	/**
	* disable_irq - disable an irq and wait for completion
	* @irq: Interrupt to disable
	*
	* Disable the selected interrupt line. Enables and Disables are
	* nested.
	* This function waits for any pending IRQ handlers for this interrupt
	* to complete before returning. If you use this function while
	* holding a resource the IRQ handler may need you will deadlock.
	*
	* This function may be called - with care - from IRQ context.
	*/
	void disable_irq(unsigned int irq)
	{
	irq_desc_t *desc = irq_desc + irq;

	disable_irq_nosync(irq);
	if (desc->action)
	synchronize_irq(irq);
	}

	EXPORT_SYMBOL(disable_irq);

	/**
	* enable_irq - enable handling of an irq
	* @irq: Interrupt to enable
	*
	* Undoes the effect of one call to disable_irq(). If this
	* matches the last disable, processing of interrupts on this
	* IRQ line is re-enabled.
	*
	* This function may be called from IRQ context.
	*/
	void enable_irq(unsigned int irq)
	{
	irq_desc_t *desc = irq_desc + irq;
	unsigned long flags;

	spin_lock_irqsave(&desc->lock, flags);
	switch (desc->depth) {
	case 0:
	WARN_ON(1);
	break;
	case 1: {
	unsigned int status = desc->status & ~IRQ_DISABLED;

	desc->status = status;
	if ((status & (IRQ_PENDING \| IRQ_REPLAY)) == IRQ_PENDING) {
	desc->status = status \| IRQ_REPLAY;
	hw_resend_irq(desc->handler,irq);
	}
	desc->handler->enable(irq);
	/* fall-through */
	}
	default:
	desc->depth--;
	}
	spin_unlock_irqrestore(&desc->lock, flags);
	}

	EXPORT_SYMBOL(enable_irq);

	/*
	* Internal function that tells the architecture code whether a
	* particular irq has been exclusively allocated or is available
	* for driver use.
	*/
	int can_request_irq(unsigned int irq, unsigned long irqflags)
	{
	struct irqaction *action;

	if (irq >= NR_IRQS)
	return 0;

	action = irq_desc[irq].action;
	if (action)
	if (irqflags & action->flags & SA_SHIRQ)
	action = NULL;

	return !action;
	}

	/*
	* Internal function to register an irqaction - typically used to
	* allocate special interrupts that are part of the architecture.
	*/
	int setup_irq(unsigned int irq, struct irqaction * new)
	{
	struct irq_desc *desc = irq_desc + irq;
	struct irqaction old, *p;
	unsigned long flags;
	int shared = 0;

	if (desc->handler == &no_irq_type)
	return -ENOSYS;
	/*
	* Some drivers like serial.c use request_irq() heavily,
	* so we have to be careful not to interfere with a
	* running system.
	*/
	if (new->flags & SA_SAMPLE_RANDOM) {
	/*
	* This function might sleep, we want to call it first,
	* outside of the atomic block.
	* Yes, this might clear the entropy pool if the wrong
	* driver is attempted to be loaded, without actually
	* installing a new handler, but is this really a problem,
	* only the sysadmin is able to do this.
	*/
	rand_initialize_irq(irq);
	}

	/*
	* The following block of code has to be executed atomically
	*/
	spin_lock_irqsave(&desc->lock,flags);
	p = &desc->action;
	if ((old = *p) != NULL) {
	/* Can't share interrupts unless both agree to */
	if (!(old->flags & new->flags & SA_SHIRQ)) {
	spin_unlock_irqrestore(&desc->lock,flags);
	return -EBUSY;
	}

	/* add new interrupt at end of irq queue */
	do {
	p = &old->next;
	old = *p;
	} while (old);
	shared = 1;
	}

	*p = new;

	if (!shared) {
	desc->depth = 0;
	desc->status &= ~(IRQ_DISABLED \| IRQ_AUTODETECT \|
	IRQ_WAITING \| IRQ_INPROGRESS);
	if (desc->handler->startup)
	desc->handler->startup(irq);
	else
	desc->handler->enable(irq);
	}
	spin_unlock_irqrestore(&desc->lock,flags);

	new->irq = irq;
	register_irq_proc(irq);
	new->dir = NULL;
	register_handler_proc(irq, new);

	return 0;
	}

	/**
	* free_irq - free an interrupt
	* @irq: Interrupt line to free
	* @dev_id: Device identity to free
	*
	* Remove an interrupt handler. The handler is removed and if the
	* interrupt line is no longer in use by any driver it is disabled.
	* On a shared IRQ the caller must ensure the interrupt is disabled
	* on the card it drives before calling this function. The function
	* does not return until any executing interrupts for this IRQ
	* have completed.
	*
	* This function must not be called from interrupt context.
	*/
	void free_irq(unsigned int irq, void *dev_id)
	{
	struct irq_desc *desc;
	struct irqaction **p;
	unsigned long flags;

	if (irq >= NR_IRQS)
	return;

	desc = irq_desc + irq;
	spin_lock_irqsave(&desc->lock,flags);
	p = &desc->action;
	for (;;) {
	struct irqaction * action = *p;

	if (action) {
	struct irqaction **pp = p;

	p = &action->next;
	if (action->dev_id != dev_id)
	continue;

	/* Found it - now remove it from the list of entries */
	*pp = action->next;

	/* Currently used only by UML, might disappear one day.*/
	#ifdef CONFIG_IRQ_RELEASE_METHOD
	if (desc->handler->release)
	desc->handler->release(irq, dev_id);
	#endif

	if (!desc->action) {
	desc->status \|= IRQ_DISABLED;
	if (desc->handler->shutdown)
	desc->handler->shutdown(irq);
	else
	desc->handler->disable(irq);
	}
	spin_unlock_irqrestore(&desc->lock,flags);
	unregister_handler_proc(irq, action);

	/* Make sure it's not being used on another CPU */
	synchronize_irq(irq);
	kfree(action);
	return;
	}
	printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
	spin_unlock_irqrestore(&desc->lock,flags);
	return;
	}
	}

	EXPORT_SYMBOL(free_irq);

	/**
	* request_irq - allocate an interrupt line
	* @irq: Interrupt line to allocate
	* @handler: Function to be called when the IRQ occurs
	* @irqflags: Interrupt type flags
	* @devname: An ascii name for the claiming device
	* @dev_id: A cookie passed back to the handler function
	*
	* This call allocates interrupt resources and enables the
	* interrupt line and IRQ handling. From the point this
	* call is made your handler function may be invoked. Since
	* your handler function must clear any interrupt the board
	* raises, you must take care both to initialise your hardware
	* and to set up the interrupt handler in the right order.
	*
	* Dev_id must be globally unique. Normally the address of the
	* device data structure is used as the cookie. Since the handler
	* receives this value it makes sense to use it.
	*
	* If your interrupt is shared you must pass a non NULL dev_id
	* as this is required when freeing the interrupt.
	*
	* Flags:
	*
	* SA_SHIRQ Interrupt is shared
	* SA_INTERRUPT Disable local interrupts while processing
	* SA_SAMPLE_RANDOM The interrupt can be used for entropy
	*
	*/
	int request_irq(unsigned int irq,
	irqreturn_t (handler)(int, void , struct pt_regs *),
	unsigned long irqflags, const char * devname, void *dev_id)
	{
	struct irqaction * action;
	int retval;

	/*
	* Sanity-check: shared interrupts must pass in a real dev-ID,
	* otherwise we'll have trouble later trying to figure out
	* which interrupt is which (messes up the interrupt freeing
	* logic etc).
	*/
	if ((irqflags & SA_SHIRQ) && !dev_id)
	return -EINVAL;
	if (irq >= NR_IRQS)
	return -EINVAL;
	if (!handler)
	return -EINVAL;

	action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
	if (!action)
	return -ENOMEM;

	action->handler = handler;
	action->flags = irqflags;
	cpus_clear(action->mask);
	action->name = devname;
	action->next = NULL;
	action->dev_id = dev_id;

	retval = setup_irq(irq, action);
	if (retval)
	kfree(action);

	return retval;
	}

	EXPORT_SYMBOL(request_irq);