genirq/irqdomain: Allow irq domain aliasing

It is not uncommon (at least with the ARM stuff) to have a piece
of hardware that implements different flavours of "interrupts".
A typical example of this is the GICv3 ITS, which implements
standard PCI/MSI support, but also some form of "generic MSI".

So far, the PCI/MSI domain is registered using the ITS device_node,
so that irq_find_host can return it. On the contrary, the raw MSI
domain is not registered with an device_node, making it impossible
to be looked up by another subsystem (obviously, using the same
device_node twice would only result in confusion, as it is not
defined which one irq_find_host would return).

A solution to this is to "type" domains that may be aliasing, and
to be able to lookup an device_node that matches a given type.
For this, we introduce irq_find_matching_host() as a superset
of irq_find_host:

struct irq_domain *irq_find_matching_host(struct device_node *node,
                                enum irq_domain_bus_token bus_token);

where bus_token is the "type" we want to match the domain against
(so far, only DOMAIN_BUS_ANY is defined). This result in some
moderately invasive changes on the PPC side (which is the only
user of the .match method).

This has otherwise no functionnal change.

Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Yijing Wang <wangyijing@huawei.com>
Cc: Ma Jun <majun258@huawei.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Duc Dang <dhdang@apm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1438091186-10244-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 21 insertions, 2 deletions

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 744ac0ec98eb..91a83adf5e45 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -45,6 +45,17 @@ struct irq_data;
 /* Number of irqs reserved for a legacy isa controller */
 #define NUM_ISA_INTERRUPTS	16
 
+/*
+ * Should several domains have the same device node, but serve
+ * different purposes (for example one domain is for PCI/MSI, and the
+ * other for wired IRQs), they can be distinguished using a
+ * bus-specific token. Most domains are expected to only carry
+ * DOMAIN_BUS_ANY.
+ */
+enum irq_domain_bus_token {
+	DOMAIN_BUS_ANY		= 0,
+};
+
 /**
  * struct irq_domain_ops - Methods for irq_domain objects
  * @match: Match an interrupt controller device node to a host, returns
@@ -61,7 +72,8 @@ struct irq_data;
  * to setup the irq_desc when returning from map().
  */
 struct irq_domain_ops {
-	int (*match)(struct irq_domain *d, struct device_node *node);
+	int (*match)(struct irq_domain *d, struct device_node *node,
+		     enum irq_domain_bus_token bus_token);
 	int (*map)(struct irq_domain *d, unsigned int virq, irq_hw_number_t hw);
 	void (*unmap)(struct irq_domain *d, unsigned int virq);
 	int (*xlate)(struct irq_domain *d, struct device_node *node,
@@ -116,6 +128,7 @@ struct irq_domain {
 
 	/* Optional data */
 	struct device_node *of_node;
+	enum irq_domain_bus_token bus_token;
 	struct irq_domain_chip_generic *gc;
 #ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
 	struct irq_domain *parent;
@@ -161,9 +174,15 @@ struct irq_domain *irq_domain_add_legacy(struct device_node *of_node,
 					 irq_hw_number_t first_hwirq,
 					 const struct irq_domain_ops *ops,
 					 void *host_data);
-extern struct irq_domain *irq_find_host(struct device_node *node);
+extern struct irq_domain *irq_find_matching_host(struct device_node *node,
+						 enum irq_domain_bus_token bus_token);
 extern void irq_set_default_host(struct irq_domain *host);
 
+static inline struct irq_domain *irq_find_host(struct device_node *node)
+{
+	return irq_find_matching_host(node, DOMAIN_BUS_ANY);
+}
+
 /**
  * irq_domain_add_linear() - Allocate and register a linear revmap irq_domain.
  * @of_node: pointer to interrupt controller's device tree node.