Merge branch 'irq/for-gpio' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into devel

Documentation/driver-model/devres.txt

@@ -312,6 +312,7 @@ IRQ
   devm_irq_alloc_descs_from()
   devm_irq_alloc_generic_chip()
   devm_irq_setup_generic_chip()
+  devm_irq_sim_init()
 
 LED
   devm_led_classdev_register()

include/linux/irq.h

@@ -568,6 +568,8 @@ extern int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg);
 extern int irq_chip_pm_get(struct irq_data *data);
 extern int irq_chip_pm_put(struct irq_data *data);
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
+extern void handle_fasteoi_ack_irq(struct irq_desc *desc);
+extern void handle_fasteoi_mask_irq(struct irq_desc *desc);
 extern void irq_chip_enable_parent(struct irq_data *data);
 extern void irq_chip_disable_parent(struct irq_data *data);
 extern void irq_chip_ack_parent(struct irq_data *data);

include/linux/irq_sim.h

+#ifndef _LINUX_IRQ_SIM_H
+#define _LINUX_IRQ_SIM_H
+/*
+ * Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/irq_work.h>
+#include <linux/device.h>
+
+/*
+ * Provides a framework for allocating simulated interrupts which can be
+ * requested like normal irqs and enqueued from process context.
+ */
+
+struct irq_sim_work_ctx {
+	struct irq_work		work;
+	int			irq;
+};
+
+struct irq_sim_irq_ctx {
+	int			irqnum;
+	bool			enabled;
+};
+
+struct irq_sim {
+	struct irq_sim_work_ctx	work_ctx;
+	int			irq_base;
+	unsigned int		irq_count;
+	struct irq_sim_irq_ctx	*irqs;
+};
+
+int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs);
+int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
+		      unsigned int num_irqs);
+void irq_sim_fini(struct irq_sim *sim);
+void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
+int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
+
+#endif /* _LINUX_IRQ_SIM_H */

include/linux/irqdomain.h

@@ -460,6 +460,9 @@ extern void irq_domain_free_irqs_common(struct irq_domain *domain,
 extern void irq_domain_free_irqs_top(struct irq_domain *domain,
 				     unsigned int virq, unsigned int nr_irqs);
 
+extern int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg);
+extern int irq_domain_pop_irq(struct irq_domain *domain, int virq);
+
 extern int irq_domain_alloc_irqs_parent(struct irq_domain *domain,
 					unsigned int irq_base,
 					unsigned int nr_irqs, void *arg);

kernel/irq/Kconfig

@@ -63,11 +63,20 @@ config GENERIC_IRQ_CHIP
 config IRQ_DOMAIN
 	bool
 
+# Support for simulated interrupts
+config IRQ_SIM
+	bool
+	select IRQ_WORK
+
 # Support for hierarchical irq domains
 config IRQ_DOMAIN_HIERARCHY
 	bool
 	select IRQ_DOMAIN
 
+# Support for hierarchical fasteoi+edge and fasteoi+level handlers
+config IRQ_FASTEOI_HIERARCHY_HANDLERS
+	bool
+
 # Generic IRQ IPI support
 config GENERIC_IRQ_IPI
 	bool

kernel/irq/Makefile

@@ -4,6 +4,7 @@ obj-$(CONFIG_IRQ_TIMINGS) += timings.o
 obj-$(CONFIG_GENERIC_IRQ_CHIP) += generic-chip.o
 obj-$(CONFIG_GENERIC_IRQ_PROBE) += autoprobe.o
 obj-$(CONFIG_IRQ_DOMAIN) += irqdomain.o
+obj-$(CONFIG_IRQ_SIM) += irq_sim.o
 obj-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_GENERIC_PENDING_IRQ) += migration.o
 obj-$(CONFIG_GENERIC_IRQ_MIGRATION) += cpuhotplug.o

kernel/irq/chip.c

@@ -1092,6 +1092,112 @@ void irq_cpu_offline(void)
 }
 
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
+
+#ifdef CONFIG_IRQ_FASTEOI_HIERARCHY_HANDLERS
+/**
+ *	handle_fasteoi_ack_irq - irq handler for edge hierarchy
+ *	stacked on transparent controllers
+ *
+ *	@desc:	the interrupt description structure for this irq
+ *
+ *	Like handle_fasteoi_irq(), but for use with hierarchy where
+ *	the irq_chip also needs to have its ->irq_ack() function
+ *	called.
+ */
+void handle_fasteoi_ack_irq(struct irq_desc *desc)
+{
+	struct irq_chip *chip = desc->irq_data.chip;
+
+	raw_spin_lock(&desc->lock);
+
+	if (!irq_may_run(desc))
+		goto out;
+
+	desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING);
+
+	/*
+	 * If its disabled or no action available
+	 * then mask it and get out of here:
+	 */
+	if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) {
+		desc->istate |= IRQS_PENDING;
+		mask_irq(desc);
+		goto out;
+	}
+
+	kstat_incr_irqs_this_cpu(desc);
+	if (desc->istate & IRQS_ONESHOT)
+		mask_irq(desc);
+
+	/* Start handling the irq */
+	desc->irq_data.chip->irq_ack(&desc->irq_data);
+
+	preflow_handler(desc);
+	handle_irq_event(desc);
+
+	cond_unmask_eoi_irq(desc, chip);
+
+	raw_spin_unlock(&desc->lock);
+	return;
+out:
+	if (!(chip->flags & IRQCHIP_EOI_IF_HANDLED))
+		chip->irq_eoi(&desc->irq_data);
+	raw_spin_unlock(&desc->lock);
+}
+EXPORT_SYMBOL_GPL(handle_fasteoi_ack_irq);
+
+/**
+ *	handle_fasteoi_mask_irq - irq handler for level hierarchy
+ *	stacked on transparent controllers
+ *
+ *	@desc:	the interrupt description structure for this irq
+ *
+ *	Like handle_fasteoi_irq(), but for use with hierarchy where
+ *	the irq_chip also needs to have its ->irq_mask_ack() function
+ *	called.
+ */
+void handle_fasteoi_mask_irq(struct irq_desc *desc)
+{
+	struct irq_chip *chip = desc->irq_data.chip;
+
+	raw_spin_lock(&desc->lock);
+	mask_ack_irq(desc);
+
+	if (!irq_may_run(desc))
+		goto out;
+
+	desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING);
+
+	/*
+	 * If its disabled or no action available
+	 * then mask it and get out of here:
+	 */
+	if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) {
+		desc->istate |= IRQS_PENDING;
+		mask_irq(desc);
+		goto out;
+	}
+
+	kstat_incr_irqs_this_cpu(desc);
+	if (desc->istate & IRQS_ONESHOT)
+		mask_irq(desc);
+
+	preflow_handler(desc);
+	handle_irq_event(desc);
+
+	cond_unmask_eoi_irq(desc, chip);
+
+	raw_spin_unlock(&desc->lock);
+	return;
+out:
+	if (!(chip->flags & IRQCHIP_EOI_IF_HANDLED))
+		chip->irq_eoi(&desc->irq_data);
+	raw_spin_unlock(&desc->lock);
+}
+EXPORT_SYMBOL_GPL(handle_fasteoi_mask_irq);
+
+#endif /* CONFIG_IRQ_FASTEOI_HIERARCHY_HANDLERS */
+
 /**
  * irq_chip_enable_parent - Enable the parent interrupt (defaults to unmask if
  * NULL)
@@ -1105,6 +1211,7 @@ void irq_chip_enable_parent(struct irq_data *data)
 	else
 		data->chip->irq_unmask(data);
 }
+EXPORT_SYMBOL_GPL(irq_chip_enable_parent);
 
 /**
  * irq_chip_disable_parent - Disable the parent interrupt (defaults to mask if
@@ -1119,6 +1226,7 @@ void irq_chip_disable_parent(struct irq_data *data)
 	else
 		data->chip->irq_mask(data);
 }
+EXPORT_SYMBOL_GPL(irq_chip_disable_parent);
 
 /**
  * irq_chip_ack_parent - Acknowledge the parent interrupt
@@ -1181,6 +1289,7 @@ int irq_chip_set_affinity_parent(struct irq_data *data,
 
 	return -ENOSYS;
 }
+EXPORT_SYMBOL_GPL(irq_chip_set_affinity_parent);
 
 /**
  * irq_chip_set_type_parent - Set IRQ type on the parent interrupt

kernel/irq/irq_sim.c

+/*
+ * Copyright (C) 2017 Bartosz Golaszewski <brgl@bgdev.pl>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/irq_sim.h>
+#include <linux/irq.h>
+
+struct irq_sim_devres {
+	struct irq_sim		*sim;
+};
+
+static void irq_sim_irqmask(struct irq_data *data)
+{
+	struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
+
+	irq_ctx->enabled = false;
+}
+
+static void irq_sim_irqunmask(struct irq_data *data)
+{
+	struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
+
+	irq_ctx->enabled = true;
+}
+
+static struct irq_chip irq_sim_irqchip = {
+	.name		= "irq_sim",
+	.irq_mask	= irq_sim_irqmask,
+	.irq_unmask	= irq_sim_irqunmask,
+};
+
+static void irq_sim_handle_irq(struct irq_work *work)
+{
+	struct irq_sim_work_ctx *work_ctx;
+
+	work_ctx = container_of(work, struct irq_sim_work_ctx, work);
+	handle_simple_irq(irq_to_desc(work_ctx->irq));
+}
+
+/**
+ * irq_sim_init - Initialize the interrupt simulator: allocate a range of
+ *                dummy interrupts.
+ *
+ * @sim:        The interrupt simulator object to initialize.
+ * @num_irqs:   Number of interrupts to allocate
+ *
+ * Returns 0 on success and a negative error number on failure.
+ */
+int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
+{
+	int i;
+
+	sim->irqs = kmalloc_array(num_irqs, sizeof(*sim->irqs), GFP_KERNEL);
+	if (!sim->irqs)
+		return -ENOMEM;
+
+	sim->irq_base = irq_alloc_descs(-1, 0, num_irqs, 0);
+	if (sim->irq_base < 0) {
+		kfree(sim->irqs);
+		return sim->irq_base;
+	}
+
+	for (i = 0; i < num_irqs; i++) {
+		sim->irqs[i].irqnum = sim->irq_base + i;
+		sim->irqs[i].enabled = false;
+		irq_set_chip(sim->irq_base + i, &irq_sim_irqchip);
+		irq_set_chip_data(sim->irq_base + i, &sim->irqs[i]);
+		irq_set_handler(sim->irq_base + i, &handle_simple_irq);
+		irq_modify_status(sim->irq_base + i,
+				  IRQ_NOREQUEST | IRQ_NOAUTOEN, IRQ_NOPROBE);
+	}
+
+	init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq);
+	sim->irq_count = num_irqs;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_sim_init);
+
+/**
+ * irq_sim_fini - Deinitialize the interrupt simulator: free the interrupt
+ *                descriptors and allocated memory.
+ *
+ * @sim:        The interrupt simulator to tear down.
+ */
+void irq_sim_fini(struct irq_sim *sim)
+{
+	irq_work_sync(&sim->work_ctx.work);
+	irq_free_descs(sim->irq_base, sim->irq_count);
+	kfree(sim->irqs);
+}
+EXPORT_SYMBOL_GPL(irq_sim_fini);
+
+static void devm_irq_sim_release(struct device *dev, void *res)
+{
+	struct irq_sim_devres *this = res;
+
+	irq_sim_fini(this->sim);
+}
+
+/**
+ * irq_sim_init - Initialize the interrupt simulator for a managed device.
+ *
+ * @dev:        Device to initialize the simulator object for.
+ * @sim:        The interrupt simulator object to initialize.
+ * @num_irqs:   Number of interrupts to allocate
+ *
+ * Returns 0 on success and a negative error number on failure.
+ */
+int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
+		      unsigned int num_irqs)
+{
+	struct irq_sim_devres *dr;
+	int rv;
+
+	dr = devres_alloc(devm_irq_sim_release, sizeof(*dr), GFP_KERNEL);
+	if (!dr)
+		return -ENOMEM;
+
+	rv = irq_sim_init(sim, num_irqs);
+	if (rv) {
+		devres_free(dr);
+		return rv;
+	}
+
+	dr->sim = sim;
+	devres_add(dev, dr);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devm_irq_sim_init);
+
+/**
+ * irq_sim_fire - Enqueue an interrupt.
+ *
+ * @sim:        The interrupt simulator object.
+ * @offset:     Offset of the simulated interrupt which should be fired.
+ */
+void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
+{
+	if (sim->irqs[offset].enabled) {
+		sim->work_ctx.irq = irq_sim_irqnum(sim, offset);
+		irq_work_queue(&sim->work_ctx.work);
+	}
+}
+EXPORT_SYMBOL_GPL(irq_sim_fire);
+
+/**
+ * irq_sim_irqnum - Get the allocated number of a dummy interrupt.
+ *
+ * @sim:        The interrupt simulator object.
+ * @offset:     Offset of the simulated interrupt for which to retrieve
+ *              the number.
+ */
+int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset)
+{
+	return sim->irqs[offset].irqnum;
+}
+EXPORT_SYMBOL_GPL(irq_sim_irqnum);

kernel/irq/irqdomain.c

@@ -455,6 +455,31 @@ void irq_set_default_host(struct irq_domain *domain)
 }
 EXPORT_SYMBOL_GPL(irq_set_default_host);
 
+static void irq_domain_clear_mapping(struct irq_domain *domain,
+				     irq_hw_number_t hwirq)
+{
+	if (hwirq < domain->revmap_size) {
+		domain->linear_revmap[hwirq] = 0;
+	} else {
+		mutex_lock(&revmap_trees_mutex);
+		radix_tree_delete(&domain->revmap_tree, hwirq);
+		mutex_unlock(&revmap_trees_mutex);
+	}
+}
+
+static void irq_domain_set_mapping(struct irq_domain *domain,
+				   irq_hw_number_t hwirq,
+				   struct irq_data *irq_data)
+{
+	if (hwirq < domain->revmap_size) {
+		domain->linear_revmap[hwirq] = irq_data->irq;
+	} else {
+		mutex_lock(&revmap_trees_mutex);
+		radix_tree_insert(&domain->revmap_tree, hwirq, irq_data);
+		mutex_unlock(&revmap_trees_mutex);
+	}
+}
+
 void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
 {
 	struct irq_data *irq_data = irq_get_irq_data(irq);
@@ -483,13 +508,7 @@ void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
 	domain->mapcount--;
 
 	/* Clear reverse map for this hwirq */
-	if (hwirq < domain->revmap_size) {
-		domain->linear_revmap[hwirq] = 0;
-	} else {
-		mutex_lock(&revmap_trees_mutex);
-		radix_tree_delete(&domain->revmap_tree, hwirq);
-		mutex_unlock(&revmap_trees_mutex);
-	}
+	irq_domain_clear_mapping(domain, hwirq);
 }
 
 int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
@@ -533,13 +552,7 @@ int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
 	}
 
 	domain->mapcount++;
-	if (hwirq < domain->revmap_size) {
-		domain->linear_revmap[hwirq] = virq;
-	} else {
-		mutex_lock(&revmap_trees_mutex);
-		radix_tree_insert(&domain->revmap_tree, hwirq, irq_data);
-		mutex_unlock(&revmap_trees_mutex);
-	}
+	irq_domain_set_mapping(domain, hwirq, irq_data);
 	mutex_unlock(&irq_domain_mutex);
 
 	irq_clear_status_flags(virq, IRQ_NOREQUEST);
@@ -1138,16 +1151,9 @@ static void irq_domain_insert_irq(int virq)
 
 	for (data = irq_get_irq_data(virq); data; data = data->parent_data) {
 		struct irq_domain *domain = data->domain;
-		irq_hw_number_t hwirq = data->hwirq;
 
 		domain->mapcount++;
-		if (hwirq < domain->revmap_size) {
-			domain->linear_revmap[hwirq] = virq;
-		} else {
-			mutex_lock(&revmap_trees_mutex);
-			radix_tree_insert(&domain->revmap_tree, hwirq, data);
-			mutex_unlock(&revmap_trees_mutex);
-		}
+		irq_domain_set_mapping(domain, data->hwirq, data);
 
 		/* If not already assigned, give the domain the chip's name */
 		if (!domain->name && data->chip)
@@ -1171,13 +1177,7 @@ static void irq_domain_remove_irq(int virq)
 		irq_hw_number_t hwirq = data->hwirq;
 
 		domain->mapcount--;
-		if (hwirq < domain->revmap_size) {
-			domain->linear_revmap[hwirq] = 0;
-		} else {
-			mutex_lock(&revmap_trees_mutex);
-			radix_tree_delete(&domain->revmap_tree, hwirq);
-			mutex_unlock(&revmap_trees_mutex);
-		}
+		irq_domain_clear_mapping(domain, hwirq);
 	}
 }
 
@@ -1362,7 +1362,8 @@ static void irq_domain_free_irqs_hierarchy(struct irq_domain *domain,
 					   unsigned int irq_base,
 					   unsigned int nr_irqs)
 {
-	domain->ops->free(domain, irq_base, nr_irqs);
+	if (domain->ops->free)
+		domain->ops->free(domain, irq_base, nr_irqs);
 }
 
 int irq_domain_alloc_irqs_hierarchy(struct irq_domain *domain,
@@ -1448,6 +1449,175 @@ int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base,
 	return ret;
 }
 
+/* The irq_data was moved, fix the revmap to refer to the new location */
+static void irq_domain_fix_revmap(struct irq_data *d)
+{
+	void **slot;
+
+	if (d->hwirq < d->domain->revmap_size)
+		return; /* Not using radix tree. */
+
+	/* Fix up the revmap. */
+	mutex_lock(&revmap_trees_mutex);
+	slot = radix_tree_lookup_slot(&d->domain->revmap_tree, d->hwirq);
+	if (slot)
+		radix_tree_replace_slot(&d->domain->revmap_tree, slot, d);
+	mutex_unlock(&revmap_trees_mutex);
+}
+
+/**
+ * irq_domain_push_irq() - Push a domain in to the top of a hierarchy.
+ * @domain:	Domain to push.
+ * @virq:	Irq to push the domain in to.
+ * @arg:	Passed to the irq_domain_ops alloc() function.
+ *
+ * For an already existing irqdomain hierarchy, as might be obtained
+ * via a call to pci_enable_msix(), add an additional domain to the
+ * head of the processing chain.  Must be called before request_irq()
+ * has been called.
+ */
+int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg)
+{
+	struct irq_data *child_irq_data;
+	struct irq_data *root_irq_data = irq_get_irq_data(virq);
+	struct irq_desc *desc;
+	int rv = 0;
+
+	/*
+	 * Check that no action has been set, which indicates the virq
+	 * is in a state where this function doesn't have to deal with
+	 * races between interrupt handling and maintaining the
+	 * hierarchy.  This will catch gross misuse.  Attempting to
+	 * make the check race free would require holding locks across
+	 * calls to struct irq_domain_ops->alloc(), which could lead
+	 * to deadlock, so we just do a simple check before starting.
+	 */
+	desc = irq_to_desc(virq);
+	if (!desc)
+		return -EINVAL;
+	if (WARN_ON(desc->action))
+		return -EBUSY;
+
+	if (domain == NULL)
+		return -EINVAL;
+
+	if (WARN_ON(!irq_domain_is_hierarchy(domain)))
+		return -EINVAL;
+
+	if (domain->parent != root_irq_data->domain)
+		return -EINVAL;
+
+	if (!root_irq_data)
+		return -EINVAL;
+
+	child_irq_data = kzalloc_node(sizeof(*child_irq_data), GFP_KERNEL,
+				      irq_data_get_node(root_irq_data));
+	if (!child_irq_data)
+		return -ENOMEM;
+
+	mutex_lock(&irq_domain_mutex);
+
+	/* Copy the original irq_data. */
+	*child_irq_data = *root_irq_data;
+
+	/*
+	 * Overwrite the root_irq_data, which is embedded in struct
+	 * irq_desc, with values for this domain.
+	 */
+	root_irq_data->parent_data = child_irq_data;
+	root_irq_data->domain = domain;
+	root_irq_data->mask = 0;
+	root_irq_data->hwirq = 0;
+	root_irq_data->chip = NULL;
+	root_irq_data->chip_data = NULL;
+
+	/* May (probably does) set hwirq, chip, etc. */
+	rv = irq_domain_alloc_irqs_hierarchy(domain, virq, 1, arg);
+	if (rv) {
+		/* Restore the original irq_data. */
+		*root_irq_data = *child_irq_data;
+		goto error;
+	}
+
+	irq_domain_fix_revmap(child_irq_data);
+	irq_domain_set_mapping(domain, root_irq_data->hwirq, root_irq_data);
+
+error:
+	mutex_unlock(&irq_domain_mutex);
+
+	return rv;
+}
+EXPORT_SYMBOL_GPL(irq_domain_push_irq);
+
+/**
+ * irq_domain_pop_irq() - Remove a domain from the top of a hierarchy.
+ * @domain:	Domain to remove.
+ * @virq:	Irq to remove the domain from.
+ *
+ * Undo the effects of a call to irq_domain_push_irq().  Must be
+ * called either before request_irq() or after free_irq().
+ */
+int irq_domain_pop_irq(struct irq_domain *domain, int virq)
+{
+	struct irq_data *root_irq_data = irq_get_irq_data(virq);
+	struct irq_data *child_irq_data;
+	struct irq_data *tmp_irq_data;
+	struct irq_desc *desc;
+
+	/*
+	 * Check that no action is set, which indicates the virq is in
+	 * a state where this function doesn't have to deal with races
+	 * between interrupt handling and maintaining the hierarchy.
+	 * This will catch gross misuse.  Attempting to make the check
+	 * race free would require holding locks across calls to
+	 * struct irq_domain_ops->free(), which could lead to
+	 * deadlock, so we just do a simple check before starting.
+	 */
+	desc = irq_to_desc(virq);
+	if (!desc)
+		return -EINVAL;
+	if (WARN_ON(desc->action))
+		return -EBUSY;
+
+	if (domain == NULL)
+		return -EINVAL;
+
+	if (!root_irq_data)
+		return -EINVAL;
+
+	tmp_irq_data = irq_domain_get_irq_data(domain, virq);
+
+	/* We can only "pop" if this domain is at the top of the list */
+	if (WARN_ON(root_irq_data != tmp_irq_data))
+		return -EINVAL;
+
+	if (WARN_ON(root_irq_data->domain != domain))
+		return -EINVAL;
+
+	child_irq_data = root_irq_data->parent_data;
+	if (WARN_ON(!child_irq_data))
+		return -EINVAL;
+
+	mutex_lock(&irq_domain_mutex);
+
+	root_irq_data->parent_data = NULL;
+
+	irq_domain_clear_mapping(domain, root_irq_data->hwirq);
+	irq_domain_free_irqs_hierarchy(domain, virq, 1);
+
+	/* Restore the original irq_data. */
+	*root_irq_data = *child_irq_data;
+
+	irq_domain_fix_revmap(root_irq_data);
+
+	mutex_unlock(&irq_domain_mutex);
+
+	kfree(child_irq_data);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_domain_pop_irq);
+
 /**
  * irq_domain_free_irqs - Free IRQ number and associated data structures
  * @virq:	base IRQ number