github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-27 16:44:58 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

Documentation: irq-domain.rst: Simple improvements

Browse Source 
The improvements include:

  * Capitals in headlines.
  * Add commas: for easier reading, it is always desired to add commas
    at some places in text. Like before adverbs or after fronted
    sentences.
  * 3rd person -> add 's' to verbs.
  * End some sentences with period and start a new one. Avoid thus heavy
    sentences.

[ tglx: Fix up subject prefix ]

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250319092951.37667-56-jirislaby@kernel.org
This commit is contained in:
Jiri Slaby (SUSE) 2025-03-19 10:29:48 +01:00 committed by Thomas Gleixner
parent 225942f06e
commit 95cfac1b2f
1 changed files with 11 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
Documentation/core-api/irq/irq-domain.rst
View File

@ -1,19 +1,19 @@
===============================================
The irq_domain interrupt number mapping library
The irq_domain Interrupt Number Mapping Library
===============================================
The current design of the Linux kernel uses a single large number
space where each separate IRQ source is assigned a different number.
This is simple when there is only one interrupt controller, but in
systems with multiple interrupt controllers the kernel must ensure
systems with multiple interrupt controllers, the kernel must ensure
that each one gets assigned non-overlapping allocations of Linux
IRQ numbers.
The number of interrupt controllers registered as unique irqchips
show a rising tendency: for example subdrivers of different kinds
shows a rising tendency. For example, subdrivers of different kinds
such as GPIO controllers avoid reimplementing identical callback
mechanisms as the IRQ core system by modelling their interrupt
handlers as irqchips, i.e. in effect cascading interrupt controllers.
handlers as irqchips. I.e. in effect cascading interrupt controllers.
Here the interrupt number loose all kind of correspondence to
hardware interrupt numbers: whereas in the past, IRQ numbers could
@ -21,15 +21,15 @@ be chosen so they matched the hardware IRQ line into the root
interrupt controller (i.e. the component actually fireing the
interrupt line to the CPU) nowadays this number is just a number.
For this reason we need a mechanism to separate controller-local
interrupt numbers, called hardware irq's, from Linux IRQ numbers.
For this reason, we need a mechanism to separate controller-local
interrupt numbers, called hardware IRQs, from Linux IRQ numbers.
The irq_alloc_desc*() and irq_free_desc*() APIs provide allocation of
irq numbers, but they don't provide any support for reverse mapping of
the controller-local IRQ (hwirq) number into the Linux IRQ number
space.
The irq_domain library adds mapping between hwirq and IRQ numbers on
The irq_domain library adds a mapping between hwirq and IRQ numbers on
top of the irq_alloc_desc*() API. An irq_domain to manage mapping is
preferred over interrupt controller drivers open coding their own
reverse mapping scheme.
@ -38,7 +38,7 @@ irq_domain also implements translation from an abstract irq_fwspec
structure to hwirq numbers (Device Tree and ACPI GSI so far), and can
be easily extended to support other IRQ topology data sources.
irq_domain usage
irq_domain Usage
================
An interrupt controller driver creates and registers an irq_domain by
@ -76,7 +76,7 @@ If the driver has the Linux IRQ number or the irq_data pointer, and
needs to know the associated hwirq number (such as in the irq_chip
callbacks) then it can be directly obtained from irq_data->hwirq.
Types of irq_domain mappings
Types of irq_domain Mappings
============================
There are several mechanisms available for reverse mapping from hwirq
@ -101,7 +101,7 @@ 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.
The majority of drivers should use the linear map.
The majority of drivers should use the Linear map.
Tree
----
@ -189,7 +189,7 @@ that the driver using the simple domain call irq_create_mapping()
before any irq_find_mapping() since the latter will actually work
for the static IRQ assignment case.
Hierarchy IRQ domain
Hierarchy IRQ Domain
--------------------
On some architectures, there may be multiple interrupt controllers