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>

1 files changed, 5 insertions, 0 deletions

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,