diff options
Diffstat (limited to 'kernel/irq/handle.c')
| -rw-r--r-- | kernel/irq/handle.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c new file mode 100644 index 00000000000..2fb0e46e11f --- /dev/null +++ b/kernel/irq/handle.c @@ -0,0 +1,193 @@ +/* + * linux/kernel/irq/handle.c + * + * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar + * + * This file contains the core interrupt handling code. + */ + +#include <linux/irq.h> +#include <linux/module.h> +#include <linux/random.h> +#include <linux/interrupt.h> +#include <linux/kernel_stat.h> + +#include "internals.h" + +/* + * Linux has a controller-independent interrupt architecture. + * Every controller has a 'controller-template', that is used + * by the main code to do the right thing. Each driver-visible + * interrupt source is transparently wired to the apropriate + * controller. Thus drivers need not be aware of the + * interrupt-controller. + * + * The code is designed to be easily extended with new/different + * interrupt controllers, without having to do assembly magic or + * having to touch the generic code. + * + * Controller mappings for all interrupt sources: + */ +irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = { + [0 ... NR_IRQS-1] = { + .handler = &no_irq_type, + .lock = SPIN_LOCK_UNLOCKED + } +}; + +/* + * Generic 'no controller' code + */ +static void end_none(unsigned int irq) { } +static void enable_none(unsigned int irq) { } +static void disable_none(unsigned int irq) { } +static void shutdown_none(unsigned int irq) { } +static unsigned int startup_none(unsigned int irq) { return 0; } + +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 themself. + */ + ack_bad_irq(irq); +} + +struct hw_interrupt_type no_irq_type = { + .typename = "none", + .startup = startup_none, + .shutdown = shutdown_none, + .enable = enable_none, + .disable = disable_none, + .ack = ack_none, + .end = end_none, + .set_affinity = NULL +}; + +/* + * Special, empty irq handler: + */ +irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs) +{ + return IRQ_NONE; +} + +/* + * Have got an event to handle: + */ +fastcall int handle_IRQ_event(unsigned int irq, struct pt_regs *regs, + struct irqaction *action) +{ + int ret, retval = 0, status = 0; + + if (!(action->flags & SA_INTERRUPT)) + local_irq_enable(); + + do { + ret = action->handler(irq, action->dev_id, regs); + if (ret == IRQ_HANDLED) + status |= action->flags; + retval |= ret; + action = action->next; + } while (action); + + if (status & SA_SAMPLE_RANDOM) + add_interrupt_randomness(irq); + local_irq_disable(); + + return retval; +} + +/* + * do_IRQ handles all normal device IRQ's (the special + * SMP cross-CPU interrupts have their own specific + * handlers). + */ +fastcall unsigned int __do_IRQ(unsigned int irq, struct pt_regs *regs) +{ + irq_desc_t *desc = irq_desc + irq; + struct irqaction * action; + unsigned int status; + + kstat_this_cpu.irqs[irq]++; + if (desc->status & IRQ_PER_CPU) { + irqreturn_t action_ret; + + /* + * No locking required for CPU-local interrupts: + */ + desc->handler->ack(irq); + action_ret = handle_IRQ_event(irq, regs, desc->action); + if (!noirqdebug) + note_interrupt(irq, desc, action_ret); + desc->handler->end(irq); + return 1; + } + + spin_lock(&desc->lock); + desc->handler->ack(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 (likely(!(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 (unlikely(!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. + */ + for (;;) { + irqreturn_t action_ret; + + spin_unlock(&desc->lock); + + action_ret = handle_IRQ_event(irq, regs, action); + + spin_lock(&desc->lock); + if (!noirqdebug) + note_interrupt(irq, desc, action_ret); + if (likely(!(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); + + return 1; +} + |