core-api/irq/irq-domain.rst

29 the controller-local IRQ (hwirq) number into the Linux IRQ number
32 The irq_domain library adds mapping between hwirq and IRQ numbers on
38 structure to hwirq numbers (Device Tree and ACPI GSI so far), and can
51 between hwirq and IRQ numbers.  Mappings are added to the irq_domain
53 hwirq number as arguments.  If a mapping for the hwirq doesn't already
55 the hwirq, and call the .map() callback so the driver can perform any
62   for a given domain and hwirq number, and NULL if there was no
65   hwirq number, and 0 if there was no mapping
69   domain and a hwirq number
79 needs to know the associated hwirq number (such as in the irq_chip
80 callbacks) then it can be directly obtained from irq_data->hwirq.
85 There are several mechanisms available for reverse mapping from hwirq
99 hwirq number.  When a hwirq is mapped, an irq_desc is allocated for
100 the hwirq, and the IRQ number is stored in the table.
106 as large as the largest possible hwirq number.
123 The irq_domain maintains a radix tree map from hwirq numbers to Linux
124 IRQs.  When an hwirq is mapped, an irq_desc is allocated and the
125 hwirq is used as the lookup key for the radix tree.
127 The tree map is a good choice if the hwirq number can be very large
129 hwirq number.  The disadvantage is that hwirq to IRQ number lookup is
146 The No Map mapping is to be used when the hwirq number is
182 calculated by adding a fixed offset to the hwirq number, and
185 allocated for every hwirq, even if it is unused.