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authorMark Brown <broonie@opensource.wolfsonmicro.com>2012-07-05 12:19:19 +0100
committerGrant Likely <grant.likely@secretlab.ca>2012-07-11 14:59:17 +0100
commit781d0f46d81e2c26c70649903b503bcfe817efc8 (patch)
tree11794b64c41e8468db6d14243c5becce3b5b64c8
parentaed98048bd1c83469d96932c1901e867d9ba519a (diff)
downloadblackbird-op-linux-781d0f46d81e2c26c70649903b503bcfe817efc8.tar.gz
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irq_domain: Standardise legacy/linear domain selection
A large proportion of interrupt controllers that support legacy mappings do so because non-DT systems need to use fixed IRQ numbers when registering devices via buses but can otherwise use a linear mapping. The interrupt controller itself typically is not affected by the mapping used and best practice is to use a linear mapping where possible so drivers frequently select at runtime depending on if a legacy range has been allocated to them. Standardise this behaviour by providing irq_domain_register_simple() which will allocate a linear mapping unless a positive first_irq is provided in which case it will fall back to a legacy mapping. This helps make best practice for irq_domain adoption clearer. Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
-rw-r--r--Documentation/IRQ-domain.txt5
-rw-r--r--include/linux/irqdomain.h5
-rw-r--r--kernel/irq/irqdomain.c30
3 files changed, 40 insertions, 0 deletions
diff --git a/Documentation/IRQ-domain.txt b/Documentation/IRQ-domain.txt
index 27dcaabfb4db..1401cece745a 100644
--- a/Documentation/IRQ-domain.txt
+++ b/Documentation/IRQ-domain.txt
@@ -93,6 +93,7 @@ Linux IRQ number into the hardware.
Most drivers cannot use this mapping.
==== Legacy ====
+irq_domain_add_simple()
irq_domain_add_legacy()
irq_domain_add_legacy_isa()
@@ -115,3 +116,7 @@ The legacy map should only be used if fixed IRQ mappings must be
supported. For example, ISA controllers would use the legacy map for
mapping Linux IRQs 0-15 so that existing ISA drivers get the correct IRQ
numbers.
+
+Most users of legacy mappings should use irq_domain_add_simple() which
+will use a legacy domain only if an IRQ range is supplied by the
+system and will otherwise use a linear domain mapping.
diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 5abb533eb8eb..17b60be30fff 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -112,6 +112,11 @@ struct irq_domain {
};
#ifdef CONFIG_IRQ_DOMAIN
+struct irq_domain *irq_domain_add_simple(struct device_node *of_node,
+ unsigned int size,
+ unsigned int first_irq,
+ const struct irq_domain_ops *ops,
+ void *host_data);
struct irq_domain *irq_domain_add_legacy(struct device_node *of_node,
unsigned int size,
unsigned int first_irq,
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index d3968e91bfd2..0c51958c6335 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -140,6 +140,36 @@ static unsigned int irq_domain_legacy_revmap(struct irq_domain *domain,
}
/**
+ * irq_domain_add_simple() - Allocate and register a simple irq_domain.
+ * @of_node: pointer to interrupt controller's device tree node.
+ * @size: total number of irqs in mapping
+ * @first_irq: first number of irq block assigned to the domain
+ * @ops: map/unmap domain callbacks
+ * @host_data: Controller private data pointer
+ *
+ * Allocates a legacy irq_domain if irq_base is positive or a linear
+ * domain otherwise.
+ *
+ * This is intended to implement the expected behaviour for most
+ * interrupt controllers which is that a linear mapping should
+ * normally be used unless the system requires a legacy mapping in
+ * order to support supplying interrupt numbers during non-DT
+ * registration of devices.
+ */
+struct irq_domain *irq_domain_add_simple(struct device_node *of_node,
+ unsigned int size,
+ unsigned int first_irq,
+ const struct irq_domain_ops *ops,
+ void *host_data)
+{
+ if (first_irq > 0)
+ return irq_domain_add_legacy(of_node, size, first_irq, 0,
+ ops, host_data);
+ else
+ return irq_domain_add_linear(of_node, size, ops, host_data);
+}
+
+/**
* irq_domain_add_legacy() - Allocate and register a legacy revmap irq_domain.
* @of_node: pointer to interrupt controller's device tree node.
* @size: total number of irqs in legacy mapping
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