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Documentation/IRQ-domain.txt: Document irq_domain_create_{linear, tree}

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They have the same functionalities as irq_domain_add_{linear, tree},
except fro accepting different first argument.

Signed-off-by: Jianyu Zhan <nasa4836@gmail.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Jianyu Zhan 2016-03-27 11:51:20 +08:00 committed by Jonathan Corbet
parent 83d26b6326
commit dbe7fcdaf9
1 changed files with 12 additions and 0 deletions
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Documentation/IRQ-domain.txt
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@ -70,6 +70,7 @@ of the reverse map types are described below:
==== Linear ==== ==== Linear ====
irq_domain_add_linear() irq_domain_add_linear()
irq_domain_create_linear()
The linear reverse map maintains a fixed size table indexed by the The linear reverse map maintains a fixed size table indexed by the
hwirq number. When a hwirq is mapped, an irq_desc is allocated for hwirq number. When a hwirq is mapped, an irq_desc is allocated for
@ -81,10 +82,16 @@ map are fixed time lookup for IRQ numbers, and irq_descs are only
allocated for in-use IRQs. The disadvantage is that the table must be allocated for in-use IRQs. The disadvantage is that the table must be
as large as the largest possible hwirq number. as large as the largest possible hwirq number.
irq_domain_add_linear() and irq_domain_create_linear() are functionally
equivalent, except for the first argument is different - the former
accepts an Open Firmware specific 'struct device_node', while the latter
accepts a more general abstraction 'struct fwnode_handle'.
The majority of drivers should use the linear map. The majority of drivers should use the linear map.
==== Tree ==== ==== Tree ====
irq_domain_add_tree() irq_domain_add_tree()
irq_domain_create_tree()
The irq_domain maintains a radix tree map from hwirq numbers to Linux The irq_domain maintains a radix tree map from hwirq numbers to Linux
IRQs. When an hwirq is mapped, an irq_desc is allocated and the IRQs. When an hwirq is mapped, an irq_desc is allocated and the
@ -95,6 +102,11 @@ since it doesn't need to allocate a table as large as the largest
hwirq number. The disadvantage is that hwirq to IRQ number lookup is hwirq number. The disadvantage is that hwirq to IRQ number lookup is
dependent on how many entries are in the table. dependent on how many entries are in the table.
irq_domain_add_tree() and irq_domain_create_tree() are functionally
equivalent, except for the first argument is different - the former
accepts an Open Firmware specific 'struct device_node', while the latter
accepts a more general abstraction 'struct fwnode_handle'.
Very few drivers should need this mapping. Very few drivers should need this mapping.
==== No Map ===- ==== No Map ===-