提交 dbe7fcda 编写于 作者: J Jianyu Zhan 提交者: Jonathan Corbet

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

They have the same functionalities as irq_domain_add_{linear, tree},
except fro accepting different first argument.
Signed-off-by: NJianyu Zhan <nasa4836@gmail.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
上级 83d26b63
......@@ -70,6 +70,7 @@ of the reverse map types are described below:
==== Linear ====
irq_domain_add_linear()
irq_domain_create_linear()
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
......@@ -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
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.
==== Tree ====
irq_domain_add_tree()
irq_domain_create_tree()
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
......@@ -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
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.
==== No Map ===-
......
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