/* * This file is subject to the terms and conditions of the GNU General Public * License. See the file "COPYING" in the main directory of this archive * for more details. * * Code to handle x86 style IRQs plus some generic interrupt stuff. * * Copyright (C) 1992 Linus Torvalds * Copyright (C) 1994 - 2000 Ralf Baechle */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Controller mappings for all interrupt sources: */ irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = { [0 ... NR_IRQS-1] = { 0, &no_irq_type, NULL, 0, SPIN_LOCK_UNLOCKED}}; /* * Special irq handlers. */ void no_action(int cpl, void *dev_id, struct pt_regs *regs) { } /* * Generic no controller code */ static void enable_none(unsigned int irq) { } static unsigned int startup_none(unsigned int irq) { return 0; } static void disable_none(unsigned int irq) { } static void ack_none(unsigned int irq) { /* * 'what should we do if we get a hw irq event on an illegal vector'. * each architecture has to answer this themselves, it doesnt deserve * a generic callback i think. */ printk("unexpected interrupt %d\n", irq); } /* startup is the same as "enable", shutdown is same as "disable" */ #define shutdown_none disable_none #define end_none enable_none struct hw_interrupt_type no_irq_type = { "none", startup_none, shutdown_none, enable_none, disable_none, ack_none, end_none }; volatile unsigned long irq_err_count; /* * Generic, controller-independent functions: */ int get_irq_list(char *buf) { struct irqaction * action; char *p = buf; int i; p += sprintf(p, " "); for (i=0; i < 1 /*smp_num_cpus*/; i++) p += sprintf(p, "CPU%d ", i); *p++ = '\n'; for (i = 0 ; i < NR_IRQS ; i++) { action = irq_desc[i].action; if (!action) continue; p += sprintf(p, "%3d: ",i); p += sprintf(p, "%10u ", kstat_irqs(i)); p += sprintf(p, " %14s", irq_desc[i].handler->typename); p += sprintf(p, " %s", action->name); for (action=action->next; action; action = action->next) p += sprintf(p, ", %s", action->name); *p++ = '\n'; } p += sprintf(p, "ERR: %10lu\n", irq_err_count); return p - buf; } /* * This should really return information about whether * we should do bottom half handling etc. Right now we * end up _always_ checking the bottom half, which is a * waste of time and is not what some drivers would * prefer. */ int handle_IRQ_event(unsigned int irq, struct pt_regs * regs, struct irqaction * action) { int status; int cpu = smp_processor_id(); irq_enter(cpu, irq); status = 1; /* Force the "do bottom halves" bit */ if (!(action->flags & SA_INTERRUPT)) __sti(); do { status |= action->flags; action->handler(irq, action->dev_id, regs); action = action->next; } while (action); if (status & SA_SAMPLE_RANDOM) add_interrupt_randomness(irq); __cli(); irq_exit(cpu, irq); return status; } /* * Generic enable/disable code: this just calls * down into the PIC-specific version for the actual * hardware disable after having gotten the irq * controller lock. */ /** * disable_irq_nosync - disable an irq without waiting * @irq: Interrupt to disable * * Disable the selected interrupt line. Disables of an interrupt * stack. 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 inline 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); } /** * disable_irq - disable an irq and wait for completion * @irq: Interrupt to disable * * Disable the selected interrupt line. Disables of an interrupt * stack. That is for two disables you need two enables. 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) { disable_irq_nosync(irq); if (!local_irq_count(smp_processor_id())) { do { barrier(); } while (irq_desc[irq].status & IRQ_INPROGRESS); } } /** * enable_irq - enable interrupt handling on an irq * @irq: Interrupt to enable * * Re-enables the processing of interrupts on this IRQ line * providing no disable_irq calls are now in effect. * * 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 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--; break; case 0: printk("enable_irq(%u) unbalanced from %p\n", irq, __builtin_return_address(0)); } spin_unlock_irqrestore(&desc->lock, flags); } /* * do_IRQ handles all normal device IRQ's (the special * SMP cross-CPU interrupts have their own specific * handlers). */ #ifdef CONFIG_PREEMPT_TIMES extern void latency_cause(int,int); #else #define latency_cause(a, b) #endif asmlinkage unsigned int do_IRQ(int irq, struct pt_regs *regs) { /* * We ack quickly, we don't want the irq controller * thinking we're snobs just because some other CPU has * disabled global interrupts (we have already done the * INT_ACK cycles, it's too late to try to pretend to the * controller that we aren't taking the interrupt). * * 0 return value means that this irq is already being * handled by some other CPU. (or is disabled) */ int cpu = smp_processor_id(); irq_desc_t *desc = irq_desc + irq; struct irqaction * action; unsigned int status; #ifdef CONFIG_ILATENCY { extern void interrupt_overhead_start(void); interrupt_overhead_start(); } #endif /* CONFIG_ILATENCY */ preempt_disable(); preempt_lock_start(-99); kstat.irqs[cpu][irq]++; spin_lock(&desc->lock); desc->handler->ack(irq); latency_cause(-99,~irq); /* REPLAY is when Linux resends an IRQ that was dropped earlier WAITING is used by probe to mark irqs that are being tested */ status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING); status |= IRQ_PENDING; /* we _want_ to handle it */ /* * If the IRQ is disabled for whatever reason, we cannot * use the action we have. */ action = NULL; if (!(status & (IRQ_DISABLED | IRQ_INPROGRESS))) { action = desc->action; status &= ~IRQ_PENDING; /* we commit to handling */ status |= IRQ_INPROGRESS; /* we are handling it */ } desc->status = status; /* * If there is no IRQ handler or it was disabled, exit early. Since we set PENDING, if another processor is handling a different instance of this same irq, the other processor will take care of it. */ if (!action) goto out; /* * Edge triggered interrupts need to remember * pending events. * This applies to any hw interrupts that allow a second * instance of the same irq to arrive while we are in do_IRQ * or in the handler. But the code here only handles the _second_ * instance of the irq, not the third or fourth. So it is mostly * useful for irq hardware that does not mask cleanly in an * SMP environment. */ #ifdef CONFIG_ILATENCY { extern void interrupt_overhead_stop(void); interrupt_overhead_stop(); } #endif /* CONFIG_ILATENCY */ for (;;) { spin_unlock(&desc->lock); handle_IRQ_event(irq, regs, action); spin_lock(&desc->lock); if (!(desc->status & IRQ_PENDING)) break; desc->status &= ~IRQ_PENDING; } desc->status &= ~IRQ_INPROGRESS; out: /* * The ->end() handler has to deal with interrupts which got * disabled while the handler was running. */ desc->handler->end(irq); spin_unlock(&desc->lock); preempt_lock_stop(); if (softirq_pending(cpu)) do_softirq(); #if defined(CONFIG_PREEMPT) while (--current->preempt_count == 0) { db_assert(intr_off()); db_assert(!in_interrupt()); if (current->need_resched == 0) { break; } current->preempt_count ++; sti(); if (user_mode(regs)) { schedule(); } else { preempt_schedule(); } cli(); } #endif #ifdef CONFIG_ILATENCY intr_ret_from_exception(); #endif return 1; } /** * 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, void (*handler)(int, void *, struct pt_regs *), unsigned long irqflags, const char * devname, void *dev_id) { int retval; struct irqaction * action; #if 1 /* * Sanity-check: shared interrupts should REALLY 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) { if (!dev_id) printk("Bad boy: %s (at 0x%x) called us without a dev_id!\n", devname, (&irq)[-1]); } #endif if (irq >= NR_IRQS) return -EINVAL; if (!handler) return -EINVAL; action = (struct irqaction *) kmalloc(sizeof(struct irqaction), GFP_KERNEL); if (!action) return -ENOMEM; action->handler = handler; action->flags = irqflags; action->mask = 0; action->name = devname; action->next = NULL; action->dev_id = dev_id; retval = setup_irq(irq, action); if (retval) kfree(action); return retval; } /** * 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 may be called from interrupt context. * * Bugs: Attempting to free an irq in a handler for the same irq hangs * the machine. */ void free_irq(unsigned int irq, void *dev_id) { irq_desc_t *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; if (!desc->action) { desc->status |= IRQ_DISABLED; desc->handler->shutdown(irq); } spin_unlock_irqrestore(&desc->lock,flags); #ifdef CONFIG_SMP /* Wait to make sure it's not being used on another CPU */ while (desc->status & IRQ_INPROGRESS) barrier(); #endif kfree(action); return; } printk("Trying to free free IRQ%d\n",irq); spin_unlock_irqrestore(&desc->lock,flags); return; } } /* * IRQ autodetection code.. * * This depends on the fact that any interrupt that * comes in on to an unassigned handler will get stuck * with "IRQ_WAITING" cleared and the interrupt * disabled. */ static DECLARE_MUTEX(probe_sem); /** * probe_irq_on - begin an interrupt autodetect * * Commence probing for an interrupt. The interrupts are scanned * and a mask of potential interrupt lines is returned. * */ unsigned long probe_irq_on(void) { unsigned int i; irq_desc_t *desc; unsigned long val; unsigned long delay; down(&probe_sem); /* * something may have generated an irq long ago and we want to * flush such a longstanding irq before considering it as spurious. */ for (i = NR_IRQS-1; i > 0; i--) { desc = irq_desc + i; spin_lock_irq(&desc->lock); if (!irq_desc[i].action) irq_desc[i].handler->startup(i); spin_unlock_irq(&desc->lock); } /* Wait for longstanding interrupts to trigger. */ for (delay = jiffies + HZ/50; time_after(delay, jiffies); ) /* about 20ms delay */ synchronize_irq(); /* * enable any unassigned irqs * (we must startup again here because if a longstanding irq * happened in the previous stage, it may have masked itself) */ for (i = NR_IRQS-1; i > 0; i--) { desc = irq_desc + i; spin_lock_irq(&desc->lock); if (!desc->action) { desc->status |= IRQ_AUTODETECT | IRQ_WAITING; if (desc->handler->startup(i)) desc->status |= IRQ_PENDING; } spin_unlock_irq(&desc->lock); } /* * Wait for spurious interrupts to trigger */ for (delay = jiffies + HZ/10; time_after(delay, jiffies); ) /* about 100ms delay */ synchronize_irq(); /* * Now filter out any obviously spurious interrupts */ val = 0; for (i = 0; i < NR_IRQS; i++) { irq_desc_t *desc = irq_desc + i; unsigned int status; spin_lock_irq(&desc->lock); status = desc->status; if (status & IRQ_AUTODETECT) { /* It triggered already - consider it spurious. */ if (!(status & IRQ_WAITING)) { desc->status = status & ~IRQ_AUTODETECT; desc->handler->shutdown(i); } else if (i < 32) val |= 1 << i; } spin_unlock_irq(&desc->lock); } return val; } /* * Return a mask of triggered interrupts (this * can handle only legacy ISA interrupts). */ /** * probe_irq_mask - scan a bitmap of interrupt lines * @val: mask of interrupts to consider * * Scan the ISA bus interrupt lines and return a bitmap of * active interrupts. The interrupt probe logic state is then * returned to its previous value. * * Note: we need to scan all the irq's even though we will * only return ISA irq numbers - just so that we reset them * all to a known state. */ unsigned int probe_irq_mask(unsigned long val) { int i; unsigned int mask; mask = 0; for (i = 0; i < NR_IRQS; i++) { irq_desc_t *desc = irq_desc + i; unsigned int status; spin_lock_irq(&desc->lock); status = desc->status; if (status & IRQ_AUTODETECT) { if (i < 16 && !(status & IRQ_WAITING)) mask |= 1 << i; desc->status = status & ~IRQ_AUTODETECT; desc->handler->shutdown(i); } spin_unlock_irq(&desc->lock); } up(&probe_sem); return mask & val; } /* * Return the one interrupt that triggered (this can * handle any interrupt source). */ /** * probe_irq_off - end an interrupt autodetect * @val: mask of potential interrupts (unused) * * Scans the unused interrupt lines and returns the line which * appears to have triggered the interrupt. If no interrupt was * found then zero is returned. If more than one interrupt is * found then minus the first candidate is returned to indicate * their is doubt. * * The interrupt probe logic state is returned to its previous * value. * * BUGS: When used in a module (which arguably shouldnt happen) * nothing prevents two IRQ probe callers from overlapping. The * results of this are non-optimal. */ int probe_irq_off(unsigned long val) { int i, irq_found, nr_irqs; nr_irqs = 0; irq_found = 0; for (i = 0; i < NR_IRQS; i++) { irq_desc_t *desc = irq_desc + i; unsigned int status; spin_lock_irq(&desc->lock); status = desc->status; if (status & IRQ_AUTODETECT) { if (!(status & IRQ_WAITING)) { if (!nr_irqs) irq_found = i; nr_irqs++; } desc->status = status & ~IRQ_AUTODETECT; desc->handler->shutdown(i); } spin_unlock_irq(&desc->lock); } up(&probe_sem); if (nr_irqs > 1) irq_found = -irq_found; return irq_found; } /* this was setup_x86_irq but it seems pretty generic */ int setup_irq(unsigned int irq, struct irqaction * new) { int shared = 0; unsigned long flags; struct irqaction *old, **p; irq_desc_t *desc = irq_desc + irq; /* * 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); desc->handler->startup(irq); } spin_unlock_irqrestore(&desc->lock,flags); /* register_irq_proc(irq); */ return 0; } void __init init_generic_irq(void) { int i; for (i = 0; i < NR_IRQS; i++) { irq_desc[i].status = IRQ_DISABLED; irq_desc[i].action = NULL; irq_desc[i].depth = 1; irq_desc[i].handler = &no_irq_type; } } EXPORT_SYMBOL(disable_irq_nosync); EXPORT_SYMBOL(disable_irq); EXPORT_SYMBOL(enable_irq); EXPORT_SYMBOL(probe_irq_mask);