9e2c986cb4
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>
60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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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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