From 9e2c986cb460bf97154f18e85aa833739a1e8dc7 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Mon, 11 Apr 2016 09:57:53 +0100 Subject: 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 Cc: Mark Rutland Cc: devicetree@vger.kernel.org Cc: Jason Cooper Cc: Will Deacon Cc: Rob Herring Link: http://lkml.kernel.org/r/1460365075-7316-4-git-send-email-marc.zyngier@arm.com Signed-off-by: Thomas Gleixner --- include/linux/irqchip/irq-partition-percpu.h | 59 ++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 include/linux/irqchip/irq-partition-percpu.h (limited to 'include/linux') diff --git a/include/linux/irqchip/irq-partition-percpu.h b/include/linux/irqchip/irq-partition-percpu.h new file mode 100644 index 000000000000..87433a5d1285 --- /dev/null +++ b/include/linux/irqchip/irq-partition-percpu.h @@ -0,0 +1,59 @@ +/* + * Copyright (C) 2016 ARM Limited, All Rights Reserved. + * Author: Marc Zyngier + * + * 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 . + */ + +#include +#include +#include + +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 -- cgit v1.2.3