/* * linux/kernel/irq/manage.c * * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar * Copyright (C) 2005-2006 Thomas Gleixner * * This file contains driver APIs to the irq subsystem. */ #include <linux/irq.h> #include <linux/module.h> #include <linux/random.h> #include <linux/interrupt.h> #include "internals.h" #ifdef CONFIG_SMP /** * synchronize_irq - wait for pending IRQ handlers (on other CPUs) * @irq: interrupt number to wait for * * 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; if (irq >= NR_IRQS) return; 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) { struct irq_desc *desc = irq_desc + irq; unsigned long flags; if (irq >= NR_IRQS) return; spin_lock_irqsave(&desc->lock, flags); if (!desc->depth++) { desc->status |= IRQ_DISABLED; desc->chip->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) { struct irq_desc *desc = irq_desc + irq; if (irq >= NR_IRQS) return; 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) { struct irq_desc *desc = irq_desc + irq; unsigned long flags; if (irq >= NR_IRQS) return; spin_lock_irqsave(&desc->lock, flags); switch (desc->depth) { case 0: printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq); WARN_ON(1); break; case 1: { unsigned int status = desc->status & ~IRQ_DISABLED; /* Prevent probing on this irq: */ desc->status = status | IRQ_NOPROBE; check_irq_resend(desc, irq); /* fall-through */ } default: desc->depth--; } spin_unlock_irqrestore(&desc->lock, flags); } EXPORT_SYMBOL(enable_irq); /** * set_irq_wake - control irq power management wakeup * @irq: interrupt to control * @on: enable/disable power management wakeup * * Enable/disable power management wakeup mode */ int set_irq_wake(unsigned int irq, unsigned int on) { struct irq_desc *desc = irq_desc + irq; unsigned long flags; int ret = -ENXIO; spin_lock_irqsave(&desc->lock, flags); if (desc->chip->set_wake) ret = desc->chip->set_wake(irq, on); spin_unlock_irqrestore(&desc->lock, flags); return ret; } EXPORT_SYMBOL(set_irq_wake); /* * 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 || irq_desc[irq].status & IRQ_NOREQUEST) return 0; action = irq_desc[irq].action; if (action) if (irqflags & action->flags & IRQF_SHARED) action = NULL; return !action; } void compat_irq_chip_set_default_handler(struct irq_desc *desc) { /* * If the architecture still has not overriden * the flow handler then zap the default. This * should catch incorrect flow-type setting. */ if (desc->handle_irq == &handle_bad_irq) desc->handle_irq = NULL; } /* * 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 (irq >= NR_IRQS) return -EINVAL; if (desc->chip == &no_irq_chip) 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 & IRQF_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; old = *p; if (old) { /* * Can't share interrupts unless both agree to and are * the same type (level, edge, polarity). So both flag * fields must have IRQF_SHARED set and the bits which * set the trigger type must match. */ if (!((old->flags & new->flags) & IRQF_SHARED) || ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) goto mismatch; #if defined(CONFIG_IRQ_PER_CPU) /* All handlers must agree on per-cpuness */ if ((old->flags & IRQF_PERCPU) != (new->flags & IRQF_PERCPU)) goto mismatch; #endif /* add new interrupt at end of irq queue */ do { p = &old->next; old = *p; } while (old); shared = 1; } *p = new; #if defined(CONFIG_IRQ_PER_CPU) if (new->flags & IRQF_PERCPU) desc->status |= IRQ_PER_CPU; #endif if (!shared) { irq_chip_set_defaults(desc->chip); /* Setup the type (level, edge polarity) if configured: */ if (new->flags & IRQF_TRIGGER_MASK) { if (desc->chip && desc->chip->set_type) desc->chip->set_type(irq, new->flags & IRQF_TRIGGER_MASK); else /* * IRQF_TRIGGER_* but the PIC does not support * multiple flow-types? */ printk(KERN_WARNING "No IRQF_TRIGGER set_type " "function for IRQ %d (%s)\n", irq, desc->chip ? desc->chip->name : "unknown"); } else compat_irq_chip_set_default_handler(desc); desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_INPROGRESS); if (!(desc->status & IRQ_NOAUTOEN)) { desc->depth = 0; desc->status &= ~IRQ_DISABLED; if (desc->chip->startup) desc->chip->startup(irq); else desc->chip->enable(irq); } else /* Undo nested disables: */ desc->depth = 1; } spin_unlock_irqrestore(&desc->lock, flags); new->irq = irq; register_irq_proc(irq); new->dir = NULL; register_handler_proc(irq, new); return 0; mismatch: spin_unlock_irqrestore(&desc->lock, flags); if (!(new->flags & IRQF_PROBE_SHARED)) { printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq); dump_stack(); } return -EBUSY; } /** * 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; WARN_ON(in_interrupt()); 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->chip->release) desc->chip->release(irq, dev_id); #endif if (!desc->action) { desc->status |= IRQ_DISABLED; if (desc->chip->shutdown) desc->chip->shutdown(irq); else desc->chip->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 already-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: * * IRQF_SHARED Interrupt is shared * IRQF_DISABLED Disable local interrupts while processing * IRQF_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 & IRQF_SHARED) && !dev_id) return -EINVAL; if (irq >= NR_IRQS) return -EINVAL; if (irq_desc[irq].status & IRQ_NOREQUEST) 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; select_smp_affinity(irq); retval = setup_irq(irq, action); if (retval) kfree(action); return retval; } EXPORT_SYMBOL(request_irq);