Initial import

1 files changed, 1891 insertions, 0 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
new file mode 100644
index 000000000..e68932bb3
--- /dev/null
+++ b/kernel/irq/manage.c
@@ -0,0 +1,1891 @@
+/*
+ * 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.
+ */
+
+#define pr_fmt(fmt) "genirq: " fmt
+
+#include <linux/irq.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/sched/rt.h>
+#include <linux/task_work.h>
+
+#include "internals.h"
+
+#ifdef CONFIG_IRQ_FORCED_THREADING
+__read_mostly bool force_irqthreads;
+
+static int __init setup_forced_irqthreads(char *arg)
+{
+	force_irqthreads = true;
+	return 0;
+}
+early_param("threadirqs", setup_forced_irqthreads);
+#endif
+
+static void __synchronize_hardirq(struct irq_desc *desc)
+{
+	bool inprogress;
+
+	do {
+		unsigned long flags;
+
+		/*
+		 * Wait until we're out of the critical section.  This might
+		 * give the wrong answer due to the lack of memory barriers.
+		 */
+		while (irqd_irq_inprogress(&desc->irq_data))
+			cpu_relax();
+
+		/* Ok, that indicated we're done: double-check carefully. */
+		raw_spin_lock_irqsave(&desc->lock, flags);
+		inprogress = irqd_irq_inprogress(&desc->irq_data);
+		raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+		/* Oops, that failed? */
+	} while (inprogress);
+}
+
+/**
+ *	synchronize_hardirq - wait for pending hard IRQ handlers (on other CPUs)
+ *	@irq: interrupt number to wait for
+ *
+ *	This function waits for any pending hard 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. It does not take associated threaded handlers
+ *	into account.
+ *
+ *	Do not use this for shutdown scenarios where you must be sure
+ *	that all parts (hardirq and threaded handler) have completed.
+ *
+ *	Returns: false if a threaded handler is active.
+ *
+ *	This function may be called - with care - from IRQ context.
+ */
+bool synchronize_hardirq(unsigned int irq)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (desc) {
+		__synchronize_hardirq(desc);
+		return !atomic_read(&desc->threads_active);
+	}
+
+	return true;
+}
+EXPORT_SYMBOL(synchronize_hardirq);
+
+/**
+ *	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_to_desc(irq);
+
+	if (desc) {
+		__synchronize_hardirq(desc);
+		/*
+		 * We made sure that no hardirq handler is
+		 * running. Now verify that no threaded handlers are
+		 * active.
+		 */
+		wait_event(desc->wait_for_threads,
+			   !atomic_read(&desc->threads_active));
+	}
+}
+EXPORT_SYMBOL(synchronize_irq);
+
+#ifdef CONFIG_SMP
+cpumask_var_t irq_default_affinity;
+
+/**
+ *	irq_can_set_affinity - Check if the affinity of a given irq can be set
+ *	@irq:		Interrupt to check
+ *
+ */
+int irq_can_set_affinity(unsigned int irq)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (!desc || !irqd_can_balance(&desc->irq_data) ||
+	    !desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
+		return 0;
+
+	return 1;
+}
+
+/**
+ *	irq_set_thread_affinity - Notify irq threads to adjust affinity
+ *	@desc:		irq descriptor which has affitnity changed
+ *
+ *	We just set IRQTF_AFFINITY and delegate the affinity setting
+ *	to the interrupt thread itself. We can not call
+ *	set_cpus_allowed_ptr() here as we hold desc->lock and this
+ *	code can be called from hard interrupt context.
+ */
+void irq_set_thread_affinity(struct irq_desc *desc)
+{
+	struct irqaction *action = desc->action;
+
+	while (action) {
+		if (action->thread)
+			set_bit(IRQTF_AFFINITY, &action->thread_flags);
+		action = action->next;
+	}
+}
+
+#ifdef CONFIG_GENERIC_PENDING_IRQ
+static inline bool irq_can_move_pcntxt(struct irq_data *data)
+{
+	return irqd_can_move_in_process_context(data);
+}
+static inline bool irq_move_pending(struct irq_data *data)
+{
+	return irqd_is_setaffinity_pending(data);
+}
+static inline void
+irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask)
+{
+	cpumask_copy(desc->pending_mask, mask);
+}
+static inline void
+irq_get_pending(struct cpumask *mask, struct irq_desc *desc)
+{
+	cpumask_copy(mask, desc->pending_mask);
+}
+#else
+static inline bool irq_can_move_pcntxt(struct irq_data *data) { return true; }
+static inline bool irq_move_pending(struct irq_data *data) { return false; }
+static inline void
+irq_copy_pending(struct irq_desc *desc, const struct cpumask *mask) { }
+static inline void
+irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
+#endif
+
+int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
+			bool force)
+{
+	struct irq_desc *desc = irq_data_to_desc(data);
+	struct irq_chip *chip = irq_data_get_irq_chip(data);
+	int ret;
+
+	ret = chip->irq_set_affinity(data, mask, force);
+	switch (ret) {
+	case IRQ_SET_MASK_OK:
+	case IRQ_SET_MASK_OK_DONE:
+		cpumask_copy(data->affinity, mask);
+	case IRQ_SET_MASK_OK_NOCOPY:
+		irq_set_thread_affinity(desc);
+		ret = 0;
+	}
+
+	return ret;
+}
+
+int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
+			    bool force)
+{
+	struct irq_chip *chip = irq_data_get_irq_chip(data);
+	struct irq_desc *desc = irq_data_to_desc(data);
+	int ret = 0;
+
+	if (!chip || !chip->irq_set_affinity)
+		return -EINVAL;
+
+	if (irq_can_move_pcntxt(data)) {
+		ret = irq_do_set_affinity(data, mask, force);
+	} else {
+		irqd_set_move_pending(data);
+		irq_copy_pending(desc, mask);
+	}
+
+	if (desc->affinity_notify) {
+		kref_get(&desc->affinity_notify->kref);
+		schedule_work(&desc->affinity_notify->work);
+	}
+	irqd_set(data, IRQD_AFFINITY_SET);
+
+	return ret;
+}
+
+int __irq_set_affinity(unsigned int irq, const struct cpumask *mask, bool force)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	unsigned long flags;
+	int ret;
+
+	if (!desc)
+		return -EINVAL;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	ret = irq_set_affinity_locked(irq_desc_get_irq_data(desc), mask, force);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	return ret;
+}
+
+int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
+
+	if (!desc)
+		return -EINVAL;
+	desc->affinity_hint = m;
+	irq_put_desc_unlock(desc, flags);
+	/* set the initial affinity to prevent every interrupt being on CPU0 */
+	if (m)
+		__irq_set_affinity(irq, m, false);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
+
+static void irq_affinity_notify(struct work_struct *work)
+{
+	struct irq_affinity_notify *notify =
+		container_of(work, struct irq_affinity_notify, work);
+	struct irq_desc *desc = irq_to_desc(notify->irq);
+	cpumask_var_t cpumask;
+	unsigned long flags;
+
+	if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
+		goto out;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	if (irq_move_pending(&desc->irq_data))
+		irq_get_pending(cpumask, desc);
+	else
+		cpumask_copy(cpumask, desc->irq_data.affinity);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	notify->notify(notify, cpumask);
+
+	free_cpumask_var(cpumask);
+out:
+	kref_put(&notify->kref, notify->release);
+}
+
+/**
+ *	irq_set_affinity_notifier - control notification of IRQ affinity changes
+ *	@irq:		Interrupt for which to enable/disable notification
+ *	@notify:	Context for notification, or %NULL to disable
+ *			notification.  Function pointers must be initialised;
+ *			the other fields will be initialised by this function.
+ *
+ *	Must be called in process context.  Notification may only be enabled
+ *	after the IRQ is allocated and must be disabled before the IRQ is
+ *	freed using free_irq().
+ */
+int
+irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irq_affinity_notify *old_notify;
+	unsigned long flags;
+
+	/* The release function is promised process context */
+	might_sleep();
+
+	if (!desc)
+		return -EINVAL;
+
+	/* Complete initialisation of *notify */
+	if (notify) {
+		notify->irq = irq;
+		kref_init(&notify->kref);
+		INIT_WORK(&notify->work, irq_affinity_notify);
+	}
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	old_notify = desc->affinity_notify;
+	desc->affinity_notify = notify;
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	if (old_notify)
+		kref_put(&old_notify->kref, old_notify->release);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
+
+#ifndef CONFIG_AUTO_IRQ_AFFINITY
+/*
+ * Generic version of the affinity autoselector.
+ */
+static int
+setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
+{
+	struct cpumask *set = irq_default_affinity;
+	int node = desc->irq_data.node;
+
+	/* Excludes PER_CPU and NO_BALANCE interrupts */
+	if (!irq_can_set_affinity(irq))
+		return 0;
+
+	/*
+	 * Preserve an userspace affinity setup, but make sure that
+	 * one of the targets is online.
+	 */
+	if (irqd_has_set(&desc->irq_data, IRQD_AFFINITY_SET)) {
+		if (cpumask_intersects(desc->irq_data.affinity,
+				       cpu_online_mask))
+			set = desc->irq_data.affinity;
+		else
+			irqd_clear(&desc->irq_data, IRQD_AFFINITY_SET);
+	}
+
+	cpumask_and(mask, cpu_online_mask, set);
+	if (node != NUMA_NO_NODE) {
+		const struct cpumask *nodemask = cpumask_of_node(node);
+
+		/* make sure at least one of the cpus in nodemask is online */
+		if (cpumask_intersects(mask, nodemask))
+			cpumask_and(mask, mask, nodemask);
+	}
+	irq_do_set_affinity(&desc->irq_data, mask, false);
+	return 0;
+}
+#else
+static inline int
+setup_affinity(unsigned int irq, struct irq_desc *d, struct cpumask *mask)
+{
+	return irq_select_affinity(irq);
+}
+#endif
+
+/*
+ * Called when affinity is set via /proc/irq
+ */
+int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	unsigned long flags;
+	int ret;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	ret = setup_affinity(irq, desc, mask);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	return ret;
+}
+
+#else
+static inline int
+setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
+{
+	return 0;
+}
+#endif
+
+void __disable_irq(struct irq_desc *desc, unsigned int irq)
+{
+	if (!desc->depth++)
+		irq_disable(desc);
+}
+
+static int __disable_irq_nosync(unsigned int irq)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
+
+	if (!desc)
+		return -EINVAL;
+	__disable_irq(desc, irq);
+	irq_put_desc_busunlock(desc, flags);
+	return 0;
+}
+
+/**
+ *	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)
+{
+	__disable_irq_nosync(irq);
+}
+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)
+{
+	if (!__disable_irq_nosync(irq))
+		synchronize_irq(irq);
+}
+EXPORT_SYMBOL(disable_irq);
+
+/**
+ *	disable_hardirq - disables an irq and waits for hardirq completion
+ *	@irq: Interrupt to disable
+ *
+ *	Disable the selected interrupt line.  Enables and Disables are
+ *	nested.
+ *	This function waits for any pending hard IRQ handlers for this
+ *	interrupt to complete before returning. If you use this function while
+ *	holding a resource the hard IRQ handler may need you will deadlock.
+ *
+ *	When used to optimistically disable an interrupt from atomic context
+ *	the return value must be checked.
+ *
+ *	Returns: false if a threaded handler is active.
+ *
+ *	This function may be called - with care - from IRQ context.
+ */
+bool disable_hardirq(unsigned int irq)
+{
+	if (!__disable_irq_nosync(irq))
+		return synchronize_hardirq(irq);
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(disable_hardirq);
+
+void __enable_irq(struct irq_desc *desc, unsigned int irq)
+{
+	switch (desc->depth) {
+	case 0:
+ err_out:
+		WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
+		break;
+	case 1: {
+		if (desc->istate & IRQS_SUSPENDED)
+			goto err_out;
+		/* Prevent probing on this irq: */
+		irq_settings_set_noprobe(desc);
+		irq_enable(desc);
+		check_irq_resend(desc, irq);
+		/* fall-through */
+	}
+	default:
+		desc->depth--;
+	}
+}
+
+/**
+ *	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 only when
+ *	desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
+ */
+void enable_irq(unsigned int irq)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
+
+	if (!desc)
+		return;
+	if (WARN(!desc->irq_data.chip,
+		 KERN_ERR "enable_irq before setup/request_irq: irq %u\n", irq))
+		goto out;
+
+	__enable_irq(desc, irq);
+out:
+	irq_put_desc_busunlock(desc, flags);
+}
+EXPORT_SYMBOL(enable_irq);
+
+static int set_irq_wake_real(unsigned int irq, unsigned int on)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	int ret = -ENXIO;
+
+	if (irq_desc_get_chip(desc)->flags &  IRQCHIP_SKIP_SET_WAKE)
+		return 0;
+
+	if (desc->irq_data.chip->irq_set_wake)
+		ret = desc->irq_data.chip->irq_set_wake(&desc->irq_data, on);
+
+	return ret;
+}
+
+/**
+ *	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, which is
+ *	disabled by default.  Enables and disables must match,
+ *	just as they match for non-wakeup mode support.
+ *
+ *	Wakeup mode lets this IRQ wake the system from sleep
+ *	states like "suspend to RAM".
+ */
+int irq_set_irq_wake(unsigned int irq, unsigned int on)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_buslock(irq, &flags, IRQ_GET_DESC_CHECK_GLOBAL);
+	int ret = 0;
+
+	if (!desc)
+		return -EINVAL;
+
+	/* wakeup-capable irqs can be shared between drivers that
+	 * don't need to have the same sleep mode behaviors.
+	 */
+	if (on) {
+		if (desc->wake_depth++ == 0) {
+			ret = set_irq_wake_real(irq, on);
+			if (ret)
+				desc->wake_depth = 0;
+			else
+				irqd_set(&desc->irq_data, IRQD_WAKEUP_STATE);
+		}
+	} else {
+		if (desc->wake_depth == 0) {
+			WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
+		} else if (--desc->wake_depth == 0) {
+			ret = set_irq_wake_real(irq, on);
+			if (ret)
+				desc->wake_depth = 1;
+			else
+				irqd_clear(&desc->irq_data, IRQD_WAKEUP_STATE);
+		}
+	}
+	irq_put_desc_busunlock(desc, flags);
+	return ret;
+}
+EXPORT_SYMBOL(irq_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)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
+	int canrequest = 0;
+
+	if (!desc)
+		return 0;
+
+	if (irq_settings_can_request(desc)) {
+		if (!desc->action ||
+		    irqflags & desc->action->flags & IRQF_SHARED)
+			canrequest = 1;
+	}
+	irq_put_desc_unlock(desc, flags);
+	return canrequest;
+}
+
+int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
+		      unsigned long flags)
+{
+	struct irq_chip *chip = desc->irq_data.chip;
+	int ret, unmask = 0;
+
+	if (!chip || !chip->irq_set_type) {
+		/*
+		 * IRQF_TRIGGER_* but the PIC does not support multiple
+		 * flow-types?
+		 */
+		pr_debug("No set_type function for IRQ %d (%s)\n", irq,
+			 chip ? (chip->name ? : "unknown") : "unknown");
+		return 0;
+	}
+
+	flags &= IRQ_TYPE_SENSE_MASK;
+
+	if (chip->flags & IRQCHIP_SET_TYPE_MASKED) {
+		if (!irqd_irq_masked(&desc->irq_data))
+			mask_irq(desc);
+		if (!irqd_irq_disabled(&desc->irq_data))
+			unmask = 1;
+	}
+
+	/* caller masked out all except trigger mode flags */
+	ret = chip->irq_set_type(&desc->irq_data, flags);
+
+	switch (ret) {
+	case IRQ_SET_MASK_OK:
+	case IRQ_SET_MASK_OK_DONE:
+		irqd_clear(&desc->irq_data, IRQD_TRIGGER_MASK);
+		irqd_set(&desc->irq_data, flags);
+
+	case IRQ_SET_MASK_OK_NOCOPY:
+		flags = irqd_get_trigger_type(&desc->irq_data);
+		irq_settings_set_trigger_mask(desc, flags);
+		irqd_clear(&desc->irq_data, IRQD_LEVEL);
+		irq_settings_clr_level(desc);
+		if (flags & IRQ_TYPE_LEVEL_MASK) {
+			irq_settings_set_level(desc);
+			irqd_set(&desc->irq_data, IRQD_LEVEL);
+		}
+
+		ret = 0;
+		break;
+	default:
+		pr_err("Setting trigger mode %lu for irq %u failed (%pF)\n",
+		       flags, irq, chip->irq_set_type);
+	}
+	if (unmask)
+		unmask_irq(desc);
+	return ret;
+}
+
+#ifdef CONFIG_HARDIRQS_SW_RESEND
+int irq_set_parent(int irq, int parent_irq)
+{
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
+
+	if (!desc)
+		return -EINVAL;
+
+	desc->parent_irq = parent_irq;
+
+	irq_put_desc_unlock(desc, flags);
+	return 0;
+}
+#endif
+
+/*
+ * Default primary interrupt handler for threaded interrupts. Is
+ * assigned as primary handler when request_threaded_irq is called
+ * with handler == NULL. Useful for oneshot interrupts.
+ */
+static irqreturn_t irq_default_primary_handler(int irq, void *dev_id)
+{
+	return IRQ_WAKE_THREAD;
+}
+
+/*
+ * Primary handler for nested threaded interrupts. Should never be
+ * called.
+ */
+static irqreturn_t irq_nested_primary_handler(int irq, void *dev_id)
+{
+	WARN(1, "Primary handler called for nested irq %d\n", irq);
+	return IRQ_NONE;
+}
+
+static int irq_wait_for_interrupt(struct irqaction *action)
+{
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	while (!kthread_should_stop()) {
+
+		if (test_and_clear_bit(IRQTF_RUNTHREAD,
+				       &action->thread_flags)) {
+			__set_current_state(TASK_RUNNING);
+			return 0;
+		}
+		schedule();
+		set_current_state(TASK_INTERRUPTIBLE);
+	}
+	__set_current_state(TASK_RUNNING);
+	return -1;
+}
+
+/*
+ * Oneshot interrupts keep the irq line masked until the threaded
+ * handler finished. unmask if the interrupt has not been disabled and
+ * is marked MASKED.
+ */
+static void irq_finalize_oneshot(struct irq_desc *desc,
+				 struct irqaction *action)
+{
+	if (!(desc->istate & IRQS_ONESHOT))
+		return;
+again:
+	chip_bus_lock(desc);
+	raw_spin_lock_irq(&desc->lock);
+
+	/*
+	 * Implausible though it may be we need to protect us against
+	 * the following scenario:
+	 *
+	 * The thread is faster done than the hard interrupt handler
+	 * on the other CPU. If we unmask the irq line then the
+	 * interrupt can come in again and masks the line, leaves due
+	 * to IRQS_INPROGRESS and the irq line is masked forever.
+	 *
+	 * This also serializes the state of shared oneshot handlers
+	 * versus "desc->threads_onehsot |= action->thread_mask;" in
+	 * irq_wake_thread(). See the comment there which explains the
+	 * serialization.
+	 */
+	if (unlikely(irqd_irq_inprogress(&desc->irq_data))) {
+		raw_spin_unlock_irq(&desc->lock);
+		chip_bus_sync_unlock(desc);
+		cpu_relax();
+		goto again;
+	}
+
+	/*
+	 * Now check again, whether the thread should run. Otherwise
+	 * we would clear the threads_oneshot bit of this thread which
+	 * was just set.
+	 */
+	if (test_bit(IRQTF_RUNTHREAD, &action->thread_flags))
+		goto out_unlock;
+
+	desc->threads_oneshot &= ~action->thread_mask;
+
+	if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
+	    irqd_irq_masked(&desc->irq_data))
+		unmask_threaded_irq(desc);
+
+out_unlock:
+	raw_spin_unlock_irq(&desc->lock);
+	chip_bus_sync_unlock(desc);
+}
+
+#ifdef CONFIG_SMP
+/*
+ * Check whether we need to change the affinity of the interrupt thread.
+ */
+static void
+irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
+{
+	cpumask_var_t mask;
+	bool valid = true;
+
+	if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
+		return;
+
+	/*
+	 * In case we are out of memory we set IRQTF_AFFINITY again and
+	 * try again next time
+	 */
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
+		set_bit(IRQTF_AFFINITY, &action->thread_flags);
+		return;
+	}
+
+	raw_spin_lock_irq(&desc->lock);
+	/*
+	 * This code is triggered unconditionally. Check the affinity
+	 * mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
+	 */
+	if (desc->irq_data.affinity)
+		cpumask_copy(mask, desc->irq_data.affinity);
+	else
+		valid = false;
+	raw_spin_unlock_irq(&desc->lock);
+
+	if (valid)
+		set_cpus_allowed_ptr(current, mask);
+	free_cpumask_var(mask);
+}
+#else
+static inline void
+irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action) { }
+#endif
+
+/*
+ * Interrupts which are not explicitely requested as threaded
+ * interrupts rely on the implicit bh/preempt disable of the hard irq
+ * context. So we need to disable bh here to avoid deadlocks and other
+ * side effects.
+ */
+static irqreturn_t
+irq_forced_thread_fn(struct irq_desc *desc, struct irqaction *action)
+{
+	irqreturn_t ret;
+
+	local_bh_disable();
+	ret = action->thread_fn(action->irq, action->dev_id);
+	irq_finalize_oneshot(desc, action);
+	local_bh_enable();
+	return ret;
+}
+
+/*
+ * Interrupts explicitly requested as threaded interrupts want to be
+ * preemtible - many of them need to sleep and wait for slow busses to
+ * complete.
+ */
+static irqreturn_t irq_thread_fn(struct irq_desc *desc,
+		struct irqaction *action)
+{
+	irqreturn_t ret;
+
+	ret = action->thread_fn(action->irq, action->dev_id);
+	irq_finalize_oneshot(desc, action);
+	return ret;
+}
+
+static void wake_threads_waitq(struct irq_desc *desc)
+{
+	if (atomic_dec_and_test(&desc->threads_active))
+		wake_up(&desc->wait_for_threads);
+}
+
+static void irq_thread_dtor(struct callback_head *unused)
+{
+	struct task_struct *tsk = current;
+	struct irq_desc *desc;
+	struct irqaction *action;
+
+	if (WARN_ON_ONCE(!(current->flags & PF_EXITING)))
+		return;
+
+	action = kthread_data(tsk);
+
+	pr_err("exiting task \"%s\" (%d) is an active IRQ thread (irq %d)\n",
+	       tsk->comm, tsk->pid, action->irq);
+
+
+	desc = irq_to_desc(action->irq);
+	/*
+	 * If IRQTF_RUNTHREAD is set, we need to decrement
+	 * desc->threads_active and wake possible waiters.
+	 */
+	if (test_and_clear_bit(IRQTF_RUNTHREAD, &action->thread_flags))
+		wake_threads_waitq(desc);
+
+	/* Prevent a stale desc->threads_oneshot */
+	irq_finalize_oneshot(desc, action);
+}
+
+/*
+ * Interrupt handler thread
+ */
+static int irq_thread(void *data)
+{
+	struct callback_head on_exit_work;
+	struct irqaction *action = data;
+	struct irq_desc *desc = irq_to_desc(action->irq);
+	irqreturn_t (*handler_fn)(struct irq_desc *desc,
+			struct irqaction *action);
+
+	if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
+					&action->thread_flags))
+		handler_fn = irq_forced_thread_fn;
+	else
+		handler_fn = irq_thread_fn;
+
+	init_task_work(&on_exit_work, irq_thread_dtor);
+	task_work_add(current, &on_exit_work, false);
+
+	irq_thread_check_affinity(desc, action);
+
+	while (!irq_wait_for_interrupt(action)) {
+		irqreturn_t action_ret;
+
+		irq_thread_check_affinity(desc, action);
+
+		action_ret = handler_fn(desc, action);
+		if (action_ret == IRQ_HANDLED)
+			atomic_inc(&desc->threads_handled);
+
+		wake_threads_waitq(desc);
+	}
+
+	/*
+	 * This is the regular exit path. __free_irq() is stopping the
+	 * thread via kthread_stop() after calling
+	 * synchronize_irq(). So neither IRQTF_RUNTHREAD nor the
+	 * oneshot mask bit can be set. We cannot verify that as we
+	 * cannot touch the oneshot mask at this point anymore as
+	 * __setup_irq() might have given out currents thread_mask
+	 * again.
+	 */
+	task_work_cancel(current, irq_thread_dtor);
+	return 0;
+}
+
+/**
+ *	irq_wake_thread - wake the irq thread for the action identified by dev_id
+ *	@irq:		Interrupt line
+ *	@dev_id:	Device identity for which the thread should be woken
+ *
+ */
+void irq_wake_thread(unsigned int irq, void *dev_id)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irqaction *action;
+	unsigned long flags;
+
+	if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
+		return;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	for (action = desc->action; action; action = action->next) {
+		if (action->dev_id == dev_id) {
+			if (action->thread)
+				__irq_wake_thread(desc, action);
+			break;
+		}
+	}
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+}
+EXPORT_SYMBOL_GPL(irq_wake_thread);
+
+static void irq_setup_forced_threading(struct irqaction *new)
+{
+	if (!force_irqthreads)
+		return;
+	if (new->flags & (IRQF_NO_THREAD | IRQF_PERCPU | IRQF_ONESHOT))
+		return;
+
+	new->flags |= IRQF_ONESHOT;
+
+	if (!new->thread_fn) {
+		set_bit(IRQTF_FORCED_THREAD, &new->thread_flags);
+		new->thread_fn = new->handler;
+		new->handler = irq_default_primary_handler;
+	}
+}
+
+static int irq_request_resources(struct irq_desc *desc)
+{
+	struct irq_data *d = &desc->irq_data;
+	struct irq_chip *c = d->chip;
+
+	return c->irq_request_resources ? c->irq_request_resources(d) : 0;
+}
+
+static void irq_release_resources(struct irq_desc *desc)
+{
+	struct irq_data *d = &desc->irq_data;
+	struct irq_chip *c = d->chip;
+
+	if (c->irq_release_resources)
+		c->irq_release_resources(d);
+}
+
+/*
+ * Internal function to register an irqaction - typically used to
+ * allocate special interrupts that are part of the architecture.
+ */
+static int
+__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
+{
+	struct irqaction *old, **old_ptr;
+	unsigned long flags, thread_mask = 0;
+	int ret, nested, shared = 0;
+	cpumask_var_t mask;
+
+	if (!desc)
+		return -EINVAL;
+
+	if (desc->irq_data.chip == &no_irq_chip)
+		return -ENOSYS;
+	if (!try_module_get(desc->owner))
+		return -ENODEV;
+
+	/*
+	 * Check whether the interrupt nests into another interrupt
+	 * thread.
+	 */
+	nested = irq_settings_is_nested_thread(desc);
+	if (nested) {
+		if (!new->thread_fn) {
+			ret = -EINVAL;
+			goto out_mput;
+		}
+		/*
+		 * Replace the primary handler which was provided from
+		 * the driver for non nested interrupt handling by the
+		 * dummy function which warns when called.
+		 */
+		new->handler = irq_nested_primary_handler;
+	} else {
+		if (irq_settings_can_thread(desc))
+			irq_setup_forced_threading(new);
+	}
+
+	/*
+	 * Create a handler thread when a thread function is supplied
+	 * and the interrupt does not nest into another interrupt
+	 * thread.
+	 */
+	if (new->thread_fn && !nested) {
+		struct task_struct *t;
+		static const struct sched_param param = {
+			.sched_priority = MAX_USER_RT_PRIO/2,
+		};
+
+		t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
+				   new->name);
+		if (IS_ERR(t)) {
+			ret = PTR_ERR(t);
+			goto out_mput;
+		}
+
+		sched_setscheduler_nocheck(t, SCHED_FIFO, &param);
+
+		/*
+		 * We keep the reference to the task struct even if
+		 * the thread dies to avoid that the interrupt code
+		 * references an already freed task_struct.
+		 */
+		get_task_struct(t);
+		new->thread = t;
+		/*
+		 * Tell the thread to set its affinity. This is
+		 * important for shared interrupt handlers as we do
+		 * not invoke setup_affinity() for the secondary
+		 * handlers as everything is already set up. Even for
+		 * interrupts marked with IRQF_NO_BALANCE this is
+		 * correct as we want the thread to move to the cpu(s)
+		 * on which the requesting code placed the interrupt.
+		 */
+		set_bit(IRQTF_AFFINITY, &new->thread_flags);
+	}
+
+	if (!alloc_cpumask_var(&mask, GFP_KERNEL)) {
+		ret = -ENOMEM;
+		goto out_thread;
+	}
+
+	/*
+	 * Drivers are often written to work w/o knowledge about the
+	 * underlying irq chip implementation, so a request for a
+	 * threaded irq without a primary hard irq context handler
+	 * requires the ONESHOT flag to be set. Some irq chips like
+	 * MSI based interrupts are per se one shot safe. Check the
+	 * chip flags, so we can avoid the unmask dance at the end of
+	 * the threaded handler for those.
+	 */
+	if (desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)
+		new->flags &= ~IRQF_ONESHOT;
+
+	/*
+	 * The following block of code has to be executed atomically
+	 */
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	old_ptr = &desc->action;
+	old = *old_ptr;
+	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. Also all must
+		 * agree on ONESHOT.
+		 */
+		if (!((old->flags & new->flags) & IRQF_SHARED) ||
+		    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK) ||
+		    ((old->flags ^ new->flags) & IRQF_ONESHOT))
+			goto mismatch;
+
+		/* All handlers must agree on per-cpuness */
+		if ((old->flags & IRQF_PERCPU) !=
+		    (new->flags & IRQF_PERCPU))
+			goto mismatch;
+
+		/* add new interrupt at end of irq queue */
+		do {
+			/*
+			 * Or all existing action->thread_mask bits,
+			 * so we can find the next zero bit for this
+			 * new action.
+			 */
+			thread_mask |= old->thread_mask;
+			old_ptr = &old->next;
+			old = *old_ptr;
+		} while (old);
+		shared = 1;
+	}
+
+	/*
+	 * Setup the thread mask for this irqaction for ONESHOT. For
+	 * !ONESHOT irqs the thread mask is 0 so we can avoid a
+	 * conditional in irq_wake_thread().
+	 */
+	if (new->flags & IRQF_ONESHOT) {
+		/*
+		 * Unlikely to have 32 resp 64 irqs sharing one line,
+		 * but who knows.
+		 */
+		if (thread_mask == ~0UL) {
+			ret = -EBUSY;
+			goto out_mask;
+		}
+		/*
+		 * The thread_mask for the action is or'ed to
+		 * desc->thread_active to indicate that the
+		 * IRQF_ONESHOT thread handler has been woken, but not
+		 * yet finished. The bit is cleared when a thread
+		 * completes. When all threads of a shared interrupt
+		 * line have completed desc->threads_active becomes
+		 * zero and the interrupt line is unmasked. See
+		 * handle.c:irq_wake_thread() for further information.
+		 *
+		 * If no thread is woken by primary (hard irq context)
+		 * interrupt handlers, then desc->threads_active is
+		 * also checked for zero to unmask the irq line in the
+		 * affected hard irq flow handlers
+		 * (handle_[fasteoi|level]_irq).
+		 *
+		 * The new action gets the first zero bit of
+		 * thread_mask assigned. See the loop above which or's
+		 * all existing action->thread_mask bits.
+		 */
+		new->thread_mask = 1 << ffz(thread_mask);
+
+	} else if (new->handler == irq_default_primary_handler &&
+		   !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) {
+		/*
+		 * The interrupt was requested with handler = NULL, so
+		 * we use the default primary handler for it. But it
+		 * does not have the oneshot flag set. In combination
+		 * with level interrupts this is deadly, because the
+		 * default primary handler just wakes the thread, then
+		 * the irq lines is reenabled, but the device still
+		 * has the level irq asserted. Rinse and repeat....
+		 *
+		 * While this works for edge type interrupts, we play
+		 * it safe and reject unconditionally because we can't
+		 * say for sure which type this interrupt really
+		 * has. The type flags are unreliable as the
+		 * underlying chip implementation can override them.
+		 */
+		pr_err("Threaded irq requested with handler=NULL and !ONESHOT for irq %d\n",
+		       irq);
+		ret = -EINVAL;
+		goto out_mask;
+	}
+
+	if (!shared) {
+		ret = irq_request_resources(desc);
+		if (ret) {
+			pr_err("Failed to request resources for %s (irq %d) on irqchip %s\n",
+			       new->name, irq, desc->irq_data.chip->name);
+			goto out_mask;
+		}
+
+		init_waitqueue_head(&desc->wait_for_threads);
+
+		/* Setup the type (level, edge polarity) if configured: */
+		if (new->flags & IRQF_TRIGGER_MASK) {
+			ret = __irq_set_trigger(desc, irq,
+					new->flags & IRQF_TRIGGER_MASK);
+
+			if (ret)
+				goto out_mask;
+		}
+
+		desc->istate &= ~(IRQS_AUTODETECT | IRQS_SPURIOUS_DISABLED | \
+				  IRQS_ONESHOT | IRQS_WAITING);
+		irqd_clear(&desc->irq_data, IRQD_IRQ_INPROGRESS);
+
+		if (new->flags & IRQF_PERCPU) {
+			irqd_set(&desc->irq_data, IRQD_PER_CPU);
+			irq_settings_set_per_cpu(desc);
+		}
+
+		if (new->flags & IRQF_ONESHOT)
+			desc->istate |= IRQS_ONESHOT;
+
+		if (irq_settings_can_autoenable(desc))
+			irq_startup(desc, true);
+		else
+			/* Undo nested disables: */
+			desc->depth = 1;
+
+		/* Exclude IRQ from balancing if requested */
+		if (new->flags & IRQF_NOBALANCING) {
+			irq_settings_set_no_balancing(desc);
+			irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
+		}
+
+		/* Set default affinity mask once everything is setup */
+		setup_affinity(irq, desc, mask);
+
+	} else if (new->flags & IRQF_TRIGGER_MASK) {
+		unsigned int nmsk = new->flags & IRQF_TRIGGER_MASK;
+		unsigned int omsk = irq_settings_get_trigger_mask(desc);
+
+		if (nmsk != omsk)
+			/* hope the handler works with current  trigger mode */
+			pr_warning("irq %d uses trigger mode %u; requested %u\n",
+				   irq, nmsk, omsk);
+	}
+
+	new->irq = irq;
+	*old_ptr = new;
+
+	irq_pm_install_action(desc, new);
+
+	/* Reset broken irq detection when installing new handler */
+	desc->irq_count = 0;
+	desc->irqs_unhandled = 0;
+
+	/*
+	 * Check whether we disabled the irq via the spurious handler
+	 * before. Reenable it and give it another chance.
+	 */
+	if (shared && (desc->istate & IRQS_SPURIOUS_DISABLED)) {
+		desc->istate &= ~IRQS_SPURIOUS_DISABLED;
+		__enable_irq(desc, irq);
+	}
+
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	/*
+	 * Strictly no need to wake it up, but hung_task complains
+	 * when no hard interrupt wakes the thread up.
+	 */
+	if (new->thread)
+		wake_up_process(new->thread);
+
+	register_irq_proc(irq, desc);
+	new->dir = NULL;
+	register_handler_proc(irq, new);
+	free_cpumask_var(mask);
+
+	return 0;
+
+mismatch:
+	if (!(new->flags & IRQF_PROBE_SHARED)) {
+		pr_err("Flags mismatch irq %d. %08x (%s) vs. %08x (%s)\n",
+		       irq, new->flags, new->name, old->flags, old->name);
+#ifdef CONFIG_DEBUG_SHIRQ
+		dump_stack();
+#endif
+	}
+	ret = -EBUSY;
+
+out_mask:
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	free_cpumask_var(mask);
+
+out_thread:
+	if (new->thread) {
+		struct task_struct *t = new->thread;
+
+		new->thread = NULL;
+		kthread_stop(t);
+		put_task_struct(t);
+	}
+out_mput:
+	module_put(desc->owner);
+	return ret;
+}
+
+/**
+ *	setup_irq - setup an interrupt
+ *	@irq: Interrupt line to setup
+ *	@act: irqaction for the interrupt
+ *
+ * Used to statically setup interrupts in the early boot process.
+ */
+int setup_irq(unsigned int irq, struct irqaction *act)
+{
+	int retval;
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (WARN_ON(irq_settings_is_per_cpu_devid(desc)))
+		return -EINVAL;
+	chip_bus_lock(desc);
+	retval = __setup_irq(irq, desc, act);
+	chip_bus_sync_unlock(desc);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(setup_irq);
+
+/*
+ * Internal function to unregister an irqaction - used to free
+ * regular and special interrupts that are part of the architecture.
+ */
+static struct irqaction *__free_irq(unsigned int irq, void *dev_id)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irqaction *action, **action_ptr;
+	unsigned long flags;
+
+	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
+
+	if (!desc)
+		return NULL;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+
+	/*
+	 * There can be multiple actions per IRQ descriptor, find the right
+	 * one based on the dev_id:
+	 */
+	action_ptr = &desc->action;
+	for (;;) {
+		action = *action_ptr;
+
+		if (!action) {
+			WARN(1, "Trying to free already-free IRQ %d\n", irq);
+			raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+			return NULL;
+		}
+
+		if (action->dev_id == dev_id)
+			break;
+		action_ptr = &action->next;
+	}
+
+	/* Found it - now remove it from the list of entries: */
+	*action_ptr = action->next;
+
+	irq_pm_remove_action(desc, action);
+
+	/* If this was the last handler, shut down the IRQ line: */
+	if (!desc->action) {
+		irq_shutdown(desc);
+		irq_release_resources(desc);
+	}
+
+#ifdef CONFIG_SMP
+	/* make sure affinity_hint is cleaned up */
+	if (WARN_ON_ONCE(desc->affinity_hint))
+		desc->affinity_hint = NULL;
+#endif
+
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	unregister_handler_proc(irq, action);
+
+	/* Make sure it's not being used on another CPU: */
+	synchronize_irq(irq);
+
+#ifdef CONFIG_DEBUG_SHIRQ
+	/*
+	 * It's a shared IRQ -- the driver ought to be prepared for an IRQ
+	 * event to happen even now it's being freed, so let's make sure that
+	 * is so by doing an extra call to the handler ....
+	 *
+	 * ( We do this after actually deregistering it, to make sure that a
+	 *   'real' IRQ doesn't run in * parallel with our fake. )
+	 */
+	if (action->flags & IRQF_SHARED) {
+		local_irq_save(flags);
+		action->handler(irq, dev_id);
+		local_irq_restore(flags);
+	}
+#endif
+
+	if (action->thread) {
+		kthread_stop(action->thread);
+		put_task_struct(action->thread);
+	}
+
+	module_put(desc->owner);
+	return action;
+}
+
+/**
+ *	remove_irq - free an interrupt
+ *	@irq: Interrupt line to free
+ *	@act: irqaction for the interrupt
+ *
+ * Used to remove interrupts statically setup by the early boot process.
+ */
+void remove_irq(unsigned int irq, struct irqaction *act)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (desc && !WARN_ON(irq_settings_is_per_cpu_devid(desc)))
+	    __free_irq(irq, act->dev_id);
+}
+EXPORT_SYMBOL_GPL(remove_irq);
+
+/**
+ *	free_irq - free an interrupt allocated with request_irq
+ *	@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 = irq_to_desc(irq);
+
+	if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
+		return;
+
+#ifdef CONFIG_SMP
+	if (WARN_ON(desc->affinity_notify))
+		desc->affinity_notify = NULL;
+#endif
+
+	chip_bus_lock(desc);
+	kfree(__free_irq(irq, dev_id));
+	chip_bus_sync_unlock(desc);
+}
+EXPORT_SYMBOL(free_irq);
+
+/**
+ *	request_threaded_irq - allocate an interrupt line
+ *	@irq: Interrupt line to allocate
+ *	@handler: Function to be called when the IRQ occurs.
+ *		  Primary handler for threaded interrupts
+ *		  If NULL and thread_fn != NULL the default
+ *		  primary handler is installed
+ *	@thread_fn: Function called from the irq handler thread
+ *		    If NULL, no irq thread is created
+ *	@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.
+ *
+ *	If you want to set up a threaded irq handler for your device
+ *	then you need to supply @handler and @thread_fn. @handler is
+ *	still called in hard interrupt context and has to check
+ *	whether the interrupt originates from the device. If yes it
+ *	needs to disable the interrupt on the device and return
+ *	IRQ_WAKE_THREAD which will wake up the handler thread and run
+ *	@thread_fn. This split handler design is necessary to support
+ *	shared interrupts.
+ *
+ *	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_TRIGGER_*		Specify active edge(s) or level
+ *
+ */
+int request_threaded_irq(unsigned int irq, irq_handler_t handler,
+			 irq_handler_t thread_fn, unsigned long irqflags,
+			 const char *devname, void *dev_id)
+{
+	struct irqaction *action;
+	struct irq_desc *desc;
+	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).
+	 *
+	 * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and
+	 * it cannot be set along with IRQF_NO_SUSPEND.
+	 */
+	if (((irqflags & IRQF_SHARED) && !dev_id) ||
+	    (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
+	    ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
+		return -EINVAL;
+
+	desc = irq_to_desc(irq);
+	if (!desc)
+		return -EINVAL;
+
+	if (!irq_settings_can_request(desc) ||
+	    WARN_ON(irq_settings_is_per_cpu_devid(desc)))
+		return -EINVAL;
+
+	if (!handler) {
+		if (!thread_fn)
+			return -EINVAL;
+		handler = irq_default_primary_handler;
+	}
+
+	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
+	if (!action)
+		return -ENOMEM;
+
+	action->handler = handler;
+	action->thread_fn = thread_fn;
+	action->flags = irqflags;
+	action->name = devname;
+	action->dev_id = dev_id;
+
+	chip_bus_lock(desc);
+	retval = __setup_irq(irq, desc, action);
+	chip_bus_sync_unlock(desc);
+
+	if (retval)
+		kfree(action);
+
+#ifdef CONFIG_DEBUG_SHIRQ_FIXME
+	if (!retval && (irqflags & IRQF_SHARED)) {
+		/*
+		 * It's a shared IRQ -- the driver ought to be prepared for it
+		 * to happen immediately, so let's make sure....
+		 * We disable the irq to make sure that a 'real' IRQ doesn't
+		 * run in parallel with our fake.
+		 */
+		unsigned long flags;
+
+		disable_irq(irq);
+		local_irq_save(flags);
+
+		handler(irq, dev_id);
+
+		local_irq_restore(flags);
+		enable_irq(irq);
+	}
+#endif
+	return retval;
+}
+EXPORT_SYMBOL(request_threaded_irq);
+
+/**
+ *	request_any_context_irq - allocate an interrupt line
+ *	@irq: Interrupt line to allocate
+ *	@handler: Function to be called when the IRQ occurs.
+ *		  Threaded handler for threaded interrupts.
+ *	@flags: Interrupt type flags
+ *	@name: 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. It selects either a
+ *	hardirq or threaded handling method depending on the
+ *	context.
+ *
+ *	On failure, it returns a negative value. On success,
+ *	it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.
+ */
+int request_any_context_irq(unsigned int irq, irq_handler_t handler,
+			    unsigned long flags, const char *name, void *dev_id)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	int ret;
+
+	if (!desc)
+		return -EINVAL;
+
+	if (irq_settings_is_nested_thread(desc)) {
+		ret = request_threaded_irq(irq, NULL, handler,
+					   flags, name, dev_id);
+		return !ret ? IRQC_IS_NESTED : ret;
+	}
+
+	ret = request_irq(irq, handler, flags, name, dev_id);
+	return !ret ? IRQC_IS_HARDIRQ : ret;
+}
+EXPORT_SYMBOL_GPL(request_any_context_irq);
+
+void enable_percpu_irq(unsigned int irq, unsigned int type)
+{
+	unsigned int cpu = smp_processor_id();
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
+
+	if (!desc)
+		return;
+
+	type &= IRQ_TYPE_SENSE_MASK;
+	if (type != IRQ_TYPE_NONE) {
+		int ret;
+
+		ret = __irq_set_trigger(desc, irq, type);
+
+		if (ret) {
+			WARN(1, "failed to set type for IRQ%d\n", irq);
+			goto out;
+		}
+	}
+
+	irq_percpu_enable(desc, cpu);
+out:
+	irq_put_desc_unlock(desc, flags);
+}
+EXPORT_SYMBOL_GPL(enable_percpu_irq);
+
+void disable_percpu_irq(unsigned int irq)
+{
+	unsigned int cpu = smp_processor_id();
+	unsigned long flags;
+	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, IRQ_GET_DESC_CHECK_PERCPU);
+
+	if (!desc)
+		return;
+
+	irq_percpu_disable(desc, cpu);
+	irq_put_desc_unlock(desc, flags);
+}
+EXPORT_SYMBOL_GPL(disable_percpu_irq);
+
+/*
+ * Internal function to unregister a percpu irqaction.
+ */
+static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_id)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	struct irqaction *action;
+	unsigned long flags;
+
+	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
+
+	if (!desc)
+		return NULL;
+
+	raw_spin_lock_irqsave(&desc->lock, flags);
+
+	action = desc->action;
+	if (!action || action->percpu_dev_id != dev_id) {
+		WARN(1, "Trying to free already-free IRQ %d\n", irq);
+		goto bad;
+	}
+
+	if (!cpumask_empty(desc->percpu_enabled)) {
+		WARN(1, "percpu IRQ %d still enabled on CPU%d!\n",
+		     irq, cpumask_first(desc->percpu_enabled));
+		goto bad;
+	}
+
+	/* Found it - now remove it from the list of entries: */
+	desc->action = NULL;
+
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+	unregister_handler_proc(irq, action);
+
+	module_put(desc->owner);
+	return action;
+
+bad:
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	return NULL;
+}
+
+/**
+ *	remove_percpu_irq - free a per-cpu interrupt
+ *	@irq: Interrupt line to free
+ *	@act: irqaction for the interrupt
+ *
+ * Used to remove interrupts statically setup by the early boot process.
+ */
+void remove_percpu_irq(unsigned int irq, struct irqaction *act)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (desc && irq_settings_is_per_cpu_devid(desc))
+	    __free_percpu_irq(irq, act->percpu_dev_id);
+}
+
+/**
+ *	free_percpu_irq - free an interrupt allocated with request_percpu_irq
+ *	@irq: Interrupt line to free
+ *	@dev_id: Device identity to free
+ *
+ *	Remove a percpu interrupt handler. The handler is removed, but
+ *	the interrupt line is not disabled. This must be done on each
+ *	CPU 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_percpu_irq(unsigned int irq, void __percpu *dev_id)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (!desc || !irq_settings_is_per_cpu_devid(desc))
+		return;
+
+	chip_bus_lock(desc);
+	kfree(__free_percpu_irq(irq, dev_id));
+	chip_bus_sync_unlock(desc);
+}
+
+/**
+ *	setup_percpu_irq - setup a per-cpu interrupt
+ *	@irq: Interrupt line to setup
+ *	@act: irqaction for the interrupt
+ *
+ * Used to statically setup per-cpu interrupts in the early boot process.
+ */
+int setup_percpu_irq(unsigned int irq, struct irqaction *act)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+	int retval;
+
+	if (!desc || !irq_settings_is_per_cpu_devid(desc))
+		return -EINVAL;
+	chip_bus_lock(desc);
+	retval = __setup_irq(irq, desc, act);
+	chip_bus_sync_unlock(desc);
+
+	return retval;
+}
+
+/**
+ *	request_percpu_irq - allocate a percpu interrupt line
+ *	@irq: Interrupt line to allocate
+ *	@handler: Function to be called when the IRQ occurs.
+ *	@devname: An ascii name for the claiming device
+ *	@dev_id: A percpu cookie passed back to the handler function
+ *
+ *	This call allocates interrupt resources, but doesn't
+ *	automatically enable the interrupt. It has to be done on each
+ *	CPU using enable_percpu_irq().
+ *
+ *	Dev_id must be globally unique. It is a per-cpu variable, and
+ *	the handler gets called with the interrupted CPU's instance of
+ *	that variable.
+ */
+int request_percpu_irq(unsigned int irq, irq_handler_t handler,
+		       const char *devname, void __percpu *dev_id)
+{
+	struct irqaction *action;
+	struct irq_desc *desc;
+	int retval;
+
+	if (!dev_id)
+		return -EINVAL;
+
+	desc = irq_to_desc(irq);
+	if (!desc || !irq_settings_can_request(desc) ||
+	    !irq_settings_is_per_cpu_devid(desc))
+		return -EINVAL;
+
+	action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
+	if (!action)
+		return -ENOMEM;
+
+	action->handler = handler;
+	action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND;
+	action->name = devname;
+	action->percpu_dev_id = dev_id;
+
+	chip_bus_lock(desc);
+	retval = __setup_irq(irq, desc, action);
+	chip_bus_sync_unlock(desc);
+
+	if (retval)
+		kfree(action);
+
+	return retval;
+}
+
+/**
+ *	irq_get_irqchip_state - returns the irqchip state of a interrupt.
+ *	@irq: Interrupt line that is forwarded to a VM
+ *	@which: One of IRQCHIP_STATE_* the caller wants to know about
+ *	@state: a pointer to a boolean where the state is to be storeed
+ *
+ *	This call snapshots the internal irqchip state of an
+ *	interrupt, returning into @state the bit corresponding to
+ *	stage @which
+ *
+ *	This function should be called with preemption disabled if the
+ *	interrupt controller has per-cpu registers.
+ */
+int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
+			  bool *state)
+{
+	struct irq_desc *desc;
+	struct irq_data *data;
+	struct irq_chip *chip;
+	unsigned long flags;
+	int err = -EINVAL;
+
+	desc = irq_get_desc_buslock(irq, &flags, 0);
+	if (!desc)
+		return err;
+
+	data = irq_desc_get_irq_data(desc);
+
+	do {
+		chip = irq_data_get_irq_chip(data);
+		if (chip->irq_get_irqchip_state)
+			break;
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+		data = data->parent_data;
+#else
+		data = NULL;
+#endif
+	} while (data);
+
+	if (data)
+		err = chip->irq_get_irqchip_state(data, which, state);
+
+	irq_put_desc_busunlock(desc, flags);
+	return err;
+}
+
+/**
+ *	irq_set_irqchip_state - set the state of a forwarded interrupt.
+ *	@irq: Interrupt line that is forwarded to a VM
+ *	@which: State to be restored (one of IRQCHIP_STATE_*)
+ *	@val: Value corresponding to @which
+ *
+ *	This call sets the internal irqchip state of an interrupt,
+ *	depending on the value of @which.
+ *
+ *	This function should be called with preemption disabled if the
+ *	interrupt controller has per-cpu registers.
+ */
+int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
+			  bool val)
+{
+	struct irq_desc *desc;
+	struct irq_data *data;
+	struct irq_chip *chip;
+	unsigned long flags;
+	int err = -EINVAL;
+
+	desc = irq_get_desc_buslock(irq, &flags, 0);
+	if (!desc)
+		return err;
+
+	data = irq_desc_get_irq_data(desc);
+
+	do {
+		chip = irq_data_get_irq_chip(data);
+		if (chip->irq_set_irqchip_state)
+			break;
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+		data = data->parent_data;
+#else
+		data = NULL;
+#endif
+	} while (data);
+
+	if (data)
+		err = chip->irq_set_irqchip_state(data, which, val);
+
+	irq_put_desc_busunlock(desc, flags);
+	return err;
+}