1 files changed, 93 insertions, 0 deletions
diff --git a/include/linux/irqbypass.h b/include/linux/irqbypass.h
new file mode 100644
index 000000000000..ede1fa938152
--- /dev/null
+++ b/include/linux/irqbypass.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * IRQ offload/bypass manager
+ *
+ * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (c) 2015 Linaro Ltd.
+ */
+#ifndef IRQBYPASS_H
+#define IRQBYPASS_H
+
+#include <linux/list.h>
+
+struct eventfd_ctx;
+struct irq_bypass_consumer;
+
+/*
+ * Theory of operation
+ *
+ * The IRQ bypass manager is a simple set of lists and callbacks that allows
+ * IRQ producers (ex. physical interrupt sources) to be matched to IRQ
+ * consumers (ex. virtualization hardware that allows IRQ bypass or offload)
+ * via a shared eventfd_ctx.  Producers and consumers register independently.
+ * When a producer and consumer are paired, i.e. an eventfd match is found, the
+ * optional @stop callback will be called for each participant.  The pair will
+ * then be connected via the @add_* callbacks, and finally the optional @start
+ * callback will allow any final coordination.  When either participant is
+ * unregistered, the process is repeated using the @del_* callbacks in place of
+ * the @add_* callbacks.  eventfds must be unique per producer/consumer, 1:N
+ * pairings are not supported.
+ */
+
+struct irq_bypass_consumer;
+
+/**
+ * struct irq_bypass_producer - IRQ bypass producer definition
+ * @eventfd: eventfd context used to match producers and consumers
+ * @consumer: The connected consumer (NULL if no connection)
+ * @irq: Linux IRQ number for the producer device
+ * @add_consumer: Connect the IRQ producer to an IRQ consumer (optional)
+ * @del_consumer: Disconnect the IRQ producer from an IRQ consumer (optional)
+ * @stop: Perform any quiesce operations necessary prior to add/del (optional)
+ * @start: Perform any startup operations necessary after add/del (optional)
+ *
+ * The IRQ bypass producer structure represents an interrupt source for
+ * participation in possible host bypass, for instance an interrupt vector
+ * for a physical device assigned to a VM.
+ */
+struct irq_bypass_producer {
+	struct eventfd_ctx *eventfd;
+	struct irq_bypass_consumer *consumer;
+	int irq;
+	int (*add_consumer)(struct irq_bypass_producer *,
+			    struct irq_bypass_consumer *);
+	void (*del_consumer)(struct irq_bypass_producer *,
+			     struct irq_bypass_consumer *);
+	void (*stop)(struct irq_bypass_producer *);
+	void (*start)(struct irq_bypass_producer *);
+};
+
+/**
+ * struct irq_bypass_consumer - IRQ bypass consumer definition
+ * @eventfd: eventfd context used to match producers and consumers
+ * @producer: The connected producer (NULL if no connection)
+ * @add_producer: Connect the IRQ consumer to an IRQ producer
+ * @del_producer: Disconnect the IRQ consumer from an IRQ producer
+ * @stop: Perform any quiesce operations necessary prior to add/del (optional)
+ * @start: Perform any startup operations necessary after add/del (optional)
+ *
+ * The IRQ bypass consumer structure represents an interrupt sink for
+ * participation in possible host bypass, for instance a hypervisor may
+ * support offloads to allow bypassing the host entirely or offload
+ * portions of the interrupt handling to the VM.
+ */
+struct irq_bypass_consumer {
+	struct eventfd_ctx *eventfd;
+	struct irq_bypass_producer *producer;
+
+	int (*add_producer)(struct irq_bypass_consumer *,
+			    struct irq_bypass_producer *);
+	void (*del_producer)(struct irq_bypass_consumer *,
+			     struct irq_bypass_producer *);
+	void (*stop)(struct irq_bypass_consumer *);
+	void (*start)(struct irq_bypass_consumer *);
+};
+
+int irq_bypass_register_producer(struct irq_bypass_producer *producer,
+				 struct eventfd_ctx *eventfd, int irq);
+void irq_bypass_unregister_producer(struct irq_bypass_producer *producer);
+int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer,
+				 struct eventfd_ctx *eventfd);
+void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer);
+
+#endif /* IRQBYPASS_H */