2019-06-03 01:44:50 -04:00
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/* SPDX-License-Identifier: GPL-2.0-only */
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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: Marc 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: Thomas Gleixner <tglx@linutronix.de>
2016-04-11 04:57:53 -04:00
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/*
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* Copyright (C) 2016 ARM Limited, All Rights Reserved.
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* Author: Marc Zyngier <marc.zyngier@arm.com>
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*/
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2019-08-19 03:45:34 -04:00
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#ifndef __LINUX_IRQCHIP_IRQ_PARTITION_PERCPU_H
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#define __LINUX_IRQCHIP_IRQ_PARTITION_PERCPU_H
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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: Marc 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: Thomas Gleixner <tglx@linutronix.de>
2016-04-11 04:57:53 -04:00
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#include <linux/fwnode.h>
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#include <linux/cpumask.h>
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#include <linux/irqdomain.h>
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struct partition_affinity {
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cpumask_t mask;
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void *partition_id;
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};
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struct partition_desc;
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#ifdef CONFIG_PARTITION_PERCPU
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int partition_translate_id(struct partition_desc *desc, void *partition_id);
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struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode,
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struct partition_affinity *parts,
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int nr_parts,
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int chained_irq,
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const struct irq_domain_ops *ops);
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struct irq_domain *partition_get_domain(struct partition_desc *dsc);
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#else
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static inline int partition_translate_id(struct partition_desc *desc,
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void *partition_id)
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{
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return -EINVAL;
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}
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static inline
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struct partition_desc *partition_create_desc(struct fwnode_handle *fwnode,
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struct partition_affinity *parts,
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int nr_parts,
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int chained_irq,
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const struct irq_domain_ops *ops)
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{
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return NULL;
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}
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static inline
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struct irq_domain *partition_get_domain(struct partition_desc *dsc)
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{
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return NULL;
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}
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#endif
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2019-08-19 03:45:34 -04:00
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#endif /* __LINUX_IRQCHIP_IRQ_PARTITION_PERCPU_H */
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