Commit 781d0f46 authored by Mark Brown's avatar Mark Brown Committed by Grant Likely
Browse files

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: default avatarMark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
parent aed98048

Documentation/IRQ-domain.txt

+5 −0
Original line number Diff line number Diff line
@@ -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.

include/linux/irqdomain.h

+5 −0
Original line number Diff line number Diff line
@@ -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,

kernel/irq/irqdomain.c

+30 −0
Original line number Diff line number Diff line
@@ -139,6 +139,36 @@ static unsigned int irq_domain_legacy_revmap(struct irq_domain *domain, 
	return hwirq - first_hwirq + domain->revmap_data.legacy.first_irq;

}



/**

 * 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.

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