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Commit 9e2c986c authored by Marc Zyngier's avatar Marc Zyngier Committed by Thomas Gleixner
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irqchip: Add per-cpu interrupt partitioning library 



We've unfortunately started seeing a situation where percpu interrupts
are partitioned in the system: one arbitrary set of CPUs has an
interrupt connected to a type of device, while another disjoint
set of CPUs has the same interrupt connected to another type of device.

This makes it impossible to have a device driver requesting this interrupt
using the current percpu-interrupt abstraction, as the same interrupt number
is now potentially claimed by at least two drivers, and we forbid interrupt
sharing on per-cpu interrupt.

A solution to this is to turn things upside down. Let's assume that our
system describes all the possible partitions for a given interrupt, and
give each of them a unique identifier. It is then possible to create
a namespace where the affinity identifier itself is a form of interrupt
number. At this point, it becomes easy to implement a set of partitions
as a cascaded irqchip, each affinity identifier being the HW irq.

This allows us to keep a number of nice properties:
- Each partition results in a separate percpu-interrupt (with a restrictied
  affinity), which keeps drivers happy.
- Because the underlying interrupt is still per-cpu, the overhead of
  the indirection can be kept pretty minimal.
- The core code can ignore most of that crap.

For that purpose, we implement a small library that deals with some of
the boilerplate code, relying on platform-specific drivers to provide
a description of the affinity sets and a set of callbacks.

Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Link: http://lkml.kernel.org/r/1460365075-7316-4-git-send-email-marc.zyngier@arm.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 222df54f

drivers/irqchip/Kconfig

+3 −0
Original line number Original line Diff line number Diff line
@@ -244,3 +244,6 @@ config IRQ_MXS 
config MVEBU_ODMI

config MVEBU_ODMI

	bool

	bool

	select GENERIC_MSI_IRQ_DOMAIN

	select GENERIC_MSI_IRQ_DOMAIN



config PARTITION_PERCPU

	bool

drivers/irqchip/Makefile

+1 −0
Original line number Original line Diff line number Diff line
@@ -27,6 +27,7 @@ obj-$(CONFIG_REALVIEW_DT) += irq-gic-realview.o 
obj-$(CONFIG_ARM_GIC_V2M)		+= irq-gic-v2m.o

obj-$(CONFIG_ARM_GIC_V2M)		+= irq-gic-v2m.o

obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o irq-gic-common.o

obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o irq-gic-common.o

obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o irq-gic-v3-its-pci-msi.o irq-gic-v3-its-platform-msi.o

obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o irq-gic-v3-its-pci-msi.o irq-gic-v3-its-platform-msi.o

obj-$(CONFIG_PARTITION_PERCPU)		+= irq-partition-percpu.o

obj-$(CONFIG_HISILICON_IRQ_MBIGEN)	+= irq-mbigen.o

obj-$(CONFIG_HISILICON_IRQ_MBIGEN)	+= irq-mbigen.o

obj-$(CONFIG_ARM_NVIC)			+= irq-nvic.o

obj-$(CONFIG_ARM_NVIC)			+= irq-nvic.o

obj-$(CONFIG_ARM_VIC)			+= irq-vic.o

obj-$(CONFIG_ARM_VIC)			+= irq-vic.o

drivers/irqchip/irq-partition-percpu.c

0 → 100644
+256 −0
Original line number Original line Diff line number Diff line 
/*

 * Copyright (C) 2016 ARM Limited, All Rights Reserved.

 * Author: Marc Zyngier <marc.zyngier@arm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/bitops.h>

#include <linux/interrupt.h>

#include <linux/irqchip.h>

#include <linux/irqchip/chained_irq.h>

#include <linux/irqchip/irq-partition-percpu.h>

#include <linux/irqdomain.h>

#include <linux/seq_file.h>

#include <linux/slab.h>



struct partition_desc {

	int				nr_parts;

	struct partition_affinity	*parts;

	struct irq_domain		*domain;

	struct irq_desc			*chained_desc;

	unsigned long			*bitmap;

	struct irq_domain_ops		ops;

};



static bool partition_check_cpu(struct partition_desc *part,

				unsigned int cpu, unsigned int hwirq)

{

	return cpumask_test_cpu(cpu, &part->parts[hwirq].mask);

}



static void partition_irq_mask(struct irq_data *d)

{

	struct partition_desc *part = irq_data_get_irq_chip_data(d);

	struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);

	struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);



	if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&

	    chip->irq_mask)

		chip->irq_mask(data);

}



static void partition_irq_unmask(struct irq_data *d)

{

	struct partition_desc *part = irq_data_get_irq_chip_data(d);

	struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);

	struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);



	if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&

	    chip->irq_unmask)

		chip->irq_unmask(data);

}



static int partition_irq_set_irqchip_state(struct irq_data *d,

					   enum irqchip_irq_state which,

					   bool val)

{

	struct partition_desc *part = irq_data_get_irq_chip_data(d);

	struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);

	struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);



	if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&

	    chip->irq_set_irqchip_state)

		return chip->irq_set_irqchip_state(data, which, val);



	return -EINVAL;

}



static int partition_irq_get_irqchip_state(struct irq_data *d,

					   enum irqchip_irq_state which,

					   bool *val)

{

	struct partition_desc *part = irq_data_get_irq_chip_data(d);

	struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);

	struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);



	if (partition_check_cpu(part, smp_processor_id(), d->hwirq) &&

	    chip->irq_get_irqchip_state)

		return chip->irq_get_irqchip_state(data, which, val);



	return -EINVAL;

}



static int partition_irq_set_type(struct irq_data *d, unsigned int type)

{

	struct partition_desc *part = irq_data_get_irq_chip_data(d);

	struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);

	struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);



	if (chip->irq_set_type)

		return chip->irq_set_type(data, type);



	return -EINVAL;

}



static void partition_irq_print_chip(struct irq_data *d, struct seq_file *p)

{

	struct partition_desc *part = irq_data_get_irq_chip_data(d);

	struct irq_chip *chip = irq_desc_get_chip(part->chained_desc);

	struct irq_data *data = irq_desc_get_irq_data(part->chained_desc);



	seq_printf(p, " %5s-%lu", chip->name, data->hwirq);

}



static struct irq_chip partition_irq_chip = {

	.irq_mask		= partition_irq_mask,

	.irq_unmask		= partition_irq_unmask,

	.irq_set_type		= partition_irq_set_type,

	.irq_get_irqchip_state	= partition_irq_get_irqchip_state,

	.irq_set_irqchip_state	= partition_irq_set_irqchip_state,

	.irq_print_chip		= partition_irq_print_chip,

};



static void partition_handle_irq(struct irq_desc *desc)

{

	struct partition_desc *part = irq_desc_get_handler_data(desc);

	struct irq_chip *chip = irq_desc_get_chip(desc);

	int cpu = smp_processor_id();

	int hwirq;



	chained_irq_enter(chip, desc);



	for_each_set_bit(hwirq, part->bitmap, part->nr_parts) {

		if (partition_check_cpu(part, cpu, hwirq))

			break;

	}



	if (unlikely(hwirq == part->nr_parts)) {

		handle_bad_irq(desc);

	} else {

		unsigned int irq;

		irq = irq_find_mapping(part->domain, hwirq);

		generic_handle_irq(irq);

	}



	chained_irq_exit(chip, desc);

}



static int partition_domain_alloc(struct irq_domain *domain, unsigned int virq,

				  unsigned int nr_irqs, void *arg)

{

	int ret;

	irq_hw_number_t hwirq;

	unsigned int type;

	struct irq_fwspec *fwspec = arg;

	struct partition_desc *part;



	BUG_ON(nr_irqs != 1);

	ret = domain->ops->translate(domain, fwspec, &hwirq, &type);

	if (ret)

		return ret;



	part = domain->host_data;



	set_bit(hwirq, part->bitmap);

	irq_set_chained_handler_and_data(irq_desc_get_irq(part->chained_desc),

					 partition_handle_irq, part);

	irq_set_percpu_devid_partition(virq, &part->parts[hwirq].mask);

	irq_domain_set_info(domain, virq, hwirq, &partition_irq_chip, part,

			    handle_percpu_devid_irq, NULL, NULL);

	irq_set_status_flags(virq, IRQ_NOAUTOEN);



	return 0;

}



static void partition_domain_free(struct irq_domain *domain, unsigned int virq,

				  unsigned int nr_irqs)

{

	struct irq_data *d;



	BUG_ON(nr_irqs != 1);



	d = irq_domain_get_irq_data(domain, virq);

	irq_set_handler(virq, NULL);

	irq_domain_reset_irq_data(d);

}



int partition_translate_id(struct partition_desc *desc, void *partition_id)

{

	struct partition_affinity *part = NULL;

	int i;



	for (i = 0; i < desc->nr_parts; i++) {

		if (desc->parts[i].partition_id == partition_id) {

			part = &desc->parts[i];

			break;

		}

	}



	if (WARN_ON(!part)) {

		pr_err("Failed to find partition\n");

		return -EINVAL;

	}



	return i;

}



struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode,

					     struct partition_affinity *parts,

					     int nr_parts,

					     int chained_irq,

					     const struct irq_domain_ops *ops)

{

	struct partition_desc *desc;

	struct irq_domain *d;



	BUG_ON(!ops->select || !ops->translate);



	desc = kzalloc(sizeof(*desc), GFP_KERNEL);

	if (!desc)

		return NULL;



	desc->ops = *ops;

	desc->ops.free = partition_domain_free;

	desc->ops.alloc = partition_domain_alloc;



	d = irq_domain_create_linear(fwnode, nr_parts, &desc->ops, desc);

	if (!d)

		goto out;

	desc->domain = d;



	desc->bitmap = kzalloc(sizeof(long) * BITS_TO_LONGS(nr_parts),

			       GFP_KERNEL);

	if (WARN_ON(!desc->bitmap))

		goto out;



	desc->chained_desc = irq_to_desc(chained_irq);

	desc->nr_parts = nr_parts;

	desc->parts = parts;



	return desc;

out:

	if (d)

		irq_domain_remove(d);

	kfree(desc);



	return NULL;

}



struct irq_domain *partition_get_domain(struct partition_desc *dsc)

{

	if (dsc)

		return dsc->domain;



	return NULL;

}

include/linux/irqchip/irq-partition-percpu.h

0 → 100644
+59 −0
Original line number Original line Diff line number Diff line 
/*

 * Copyright (C) 2016 ARM Limited, All Rights Reserved.

 * Author: Marc Zyngier <marc.zyngier@arm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/fwnode.h>

#include <linux/cpumask.h>

#include <linux/irqdomain.h>



struct partition_affinity {

	cpumask_t			mask;

	void				*partition_id;

};



struct partition_desc;



#ifdef CONFIG_PARTITION_PERCPU

int partition_translate_id(struct partition_desc *desc, void *partition_id);

struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode,

					     struct partition_affinity *parts,

					     int nr_parts,

					     int chained_irq,

					     const struct irq_domain_ops *ops);

struct irq_domain *partition_get_domain(struct partition_desc *dsc);

#else

static inline int partition_translate_id(struct partition_desc *desc,

					 void *partition_id)

{

	return -EINVAL;

}



static inline

struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode,

					     struct partition_affinity *parts,

					     int nr_parts,

					     int chained_irq,

					     const struct irq_domain_ops *ops)

{

	return NULL;

}



static inline

struct irq_domain *partition_get_domain(struct partition_desc *dsc)

{

	return NULL;

}

#endif