1 files changed, 193 insertions, 0 deletions

diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
new file mode 100644
index 000000000000..2fb0e46e11f3
--- /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;
+}
+