From 781d0f46d81e2c26c70649903b503bcfe817efc8 Mon Sep 17 00:00:00 2001 From: Mark Brown Date: Thu, 5 Jul 2012 12:19:19 +0100 Subject: 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 Signed-off-by: Grant Likely --- Documentation/IRQ-domain.txt | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'Documentation') 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. -- cgit v1.2.3-58-ga151