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authorMarc Zyngier <marc.zyngier@arm.com>2016-04-11 09:57:53 +0100
committerThomas Gleixner <tglx@linutronix.de>2016-05-02 13:42:51 +0200
commit9e2c986cb460bf97154f18e85aa833739a1e8dc7 (patch)
treee99c9e595296ef212031e1ef1498458aee8711a3 /include/linux/irqchip
parent222df54fd8b7641dcc81476f157806bb3144ee1d (diff)
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>
Diffstat (limited to 'include/linux/irqchip')
-rw-r--r--include/linux/irqchip/irq-partition-percpu.h59
1 files changed, 59 insertions, 0 deletions
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 <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