Commit 76d40fae authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet
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genericirq.rst: add cross-reference links and use monospaced fonts



The document describes several functions that are documented
there via kernel doc macros. Add cross-references to them.

In order to be consistend with other documents, use monospaced
fonts for fields.
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent 3bd3b99a
......@@ -26,7 +26,7 @@ Rationale
=========
The original implementation of interrupt handling in Linux uses the
__do_IRQ() super-handler, which is able to deal with every type of
:c:func:`__do_IRQ` super-handler, which is able to deal with every type of
interrupt logic.
Originally, Russell King identified different types of handlers to build
......@@ -43,7 +43,7 @@ During the implementation we identified another type:
- Fast EOI type
In the SMP world of the __do_IRQ() super-handler another type was
In the SMP world of the :c:func:`__do_IRQ` super-handler another type was
identified:
- Per CPU type
......@@ -54,11 +54,11 @@ type. This reduces complexity in that particular code path and allows
the optimized handling of a given type.
The original general IRQ implementation used hw_interrupt_type
structures and their ->ack(), ->end() [etc.] callbacks to differentiate
structures and their ``->ack``, ``->end`` [etc.] callbacks to differentiate
the flow control in the super-handler. This leads to a mix of flow logic
and low-level hardware logic, and it also leads to unnecessary code
duplication: for example in i386, there is an ioapic_level_irq and an
ioapic_edge_irq IRQ-type which share many of the low-level details but
duplication: for example in i386, there is an ``ioapic_level_irq`` and an
``ioapic_edge_irq`` IRQ-type which share many of the low-level details but
have different flow handling.
A more natural abstraction is the clean separation of the 'irq flow' and
......@@ -83,7 +83,7 @@ IRQ-flow implementation for 'level type' interrupts and add a
(sub)architecture specific 'edge type' implementation.
To make the transition to the new model easier and prevent the breakage
of existing implementations, the __do_IRQ() super-handler is still
of existing implementations, the :c:func:`__do_IRQ` super-handler is still
available. This leads to a kind of duality for the time being. Over time
the new model should be used in more and more architectures, as it
enables smaller and cleaner IRQ subsystems. It's deprecated for three
......@@ -116,7 +116,7 @@ status information and pointers to the interrupt flow method and the
interrupt chip structure which are assigned to this interrupt.
Whenever an interrupt triggers, the low-level architecture code calls
into the generic interrupt code by calling desc->handle_irq(). This
into the generic interrupt code by calling :c:func:`desc->handle_irq`. This
high-level IRQ handling function only uses desc->irq_data.chip
primitives referenced by the assigned chip descriptor structure.
......@@ -125,27 +125,27 @@ High-level Driver API
The high-level Driver API consists of following functions:
- request_irq()
- :c:func:`request_irq`
- free_irq()
- :c:func:`free_irq`
- disable_irq()
- :c:func:`disable_irq`
- enable_irq()
- :c:func:`enable_irq`
- disable_irq_nosync() (SMP only)
- :c:func:`disable_irq_nosync` (SMP only)
- synchronize_irq() (SMP only)
- :c:func:`synchronize_irq` (SMP only)
- irq_set_irq_type()
- :c:func:`irq_set_irq_type`
- irq_set_irq_wake()
- :c:func:`irq_set_irq_wake`
- irq_set_handler_data()
- :c:func:`irq_set_handler_data`
- irq_set_chip()
- :c:func:`irq_set_chip`
- irq_set_chip_data()
- :c:func:`irq_set_chip_data`
See the autogenerated function documentation for details.
......@@ -154,19 +154,19 @@ High-level IRQ flow handlers
The generic layer provides a set of pre-defined irq-flow methods:
- handle_level_irq
- :c:func:`handle_level_irq`
- handle_edge_irq
- :c:func:`handle_edge_irq`
- handle_fasteoi_irq
- :c:func:`handle_fasteoi_irq`
- handle_simple_irq
- :c:func:`handle_simple_irq`
- handle_percpu_irq
- :c:func:`handle_percpu_irq`
- handle_edge_eoi_irq
- :c:func:`handle_edge_eoi_irq`
- handle_bad_irq
- :c:func:`handle_bad_irq`
The interrupt flow handlers (either pre-defined or architecture
specific) are assigned to specific interrupts by the architecture either
......@@ -225,9 +225,9 @@ interrupts.
The following control flow is implemented (simplified excerpt)::
desc->irq_data.chip->irq_mask_ack();
:c:func:`desc->irq_data.chip->irq_mask_ack`;
handle_irq_event(desc->action);
desc->irq_data.chip->irq_unmask();
:c:func:`desc->irq_data.chip->irq_unmask`;
Default Fast EOI IRQ flow handler
......@@ -239,7 +239,7 @@ which only need an EOI at the end of the handler.
The following control flow is implemented (simplified excerpt)::
handle_irq_event(desc->action);
desc->irq_data.chip->irq_eoi();
:c:func:`desc->irq_data.chip->irq_eoi`;
Default Edge IRQ flow handler
......@@ -251,15 +251,15 @@ interrupts.
The following control flow is implemented (simplified excerpt)::
if (desc->status & running) {
desc->irq_data.chip->irq_mask_ack();
:c:func:`desc->irq_data.chip->irq_mask_ack`;
desc->status |= pending | masked;
return;
}
desc->irq_data.chip->irq_ack();
:c:func:`desc->irq_data.chip->irq_ack`;
desc->status |= running;
do {
if (desc->status & masked)
desc->irq_data.chip->irq_unmask();
:c:func:`desc->irq_data.chip->irq_unmask`;
desc->status &= ~pending;
handle_irq_event(desc->action);
} while (status & pending);
......@@ -293,10 +293,10 @@ simplified version without locking.
The following control flow is implemented (simplified excerpt)::
if (desc->irq_data.chip->irq_ack)
desc->irq_data.chip->irq_ack();
:c:func:`desc->irq_data.chip->irq_ack`;
handle_irq_event(desc->action);
if (desc->irq_data.chip->irq_eoi)
desc->irq_data.chip->irq_eoi();
:c:func:`desc->irq_data.chip->irq_eoi`;
EOI Edge IRQ flow handler
......@@ -325,14 +325,14 @@ Delayed interrupt disable
This per interrupt selectable feature, which was introduced by Russell
King in the ARM interrupt implementation, does not mask an interrupt at
the hardware level when disable_irq() is called. The interrupt is kept
the hardware level when :c:func:`disable_irq` is called. The interrupt is kept
enabled and is masked in the flow handler when an interrupt event
happens. This prevents losing edge interrupts on hardware which does not
store an edge interrupt event while the interrupt is disabled at the
hardware level. When an interrupt arrives while the IRQ_DISABLED flag
is set, then the interrupt is masked at the hardware level and the
IRQ_PENDING bit is set. When the interrupt is re-enabled by
enable_irq() the pending bit is checked and if it is set, the interrupt
:c:func:`enable_irq` the pending bit is checked and if it is set, the interrupt
is resent either via hardware or by a software resend mechanism. (It's
necessary to enable CONFIG_HARDIRQS_SW_RESEND when you want to use
the delayed interrupt disable feature and your hardware is not capable
......@@ -342,25 +342,25 @@ configurable.
Chip-level hardware encapsulation
---------------------------------
The chip-level hardware descriptor structure irq_chip contains all the
direct chip relevant functions, which can be utilized by the irq flow
The chip-level hardware descriptor structure :c:type:`irq_chip` contains all
the direct chip relevant functions, which can be utilized by the irq flow
implementations.
- irq_ack()
- ``irq_ack``
- irq_mask_ack() - Optional, recommended for performance
- ``irq_mask_ack`` - Optional, recommended for performance
- irq_mask()
- ``irq_mask``
- irq_unmask()
- ``irq_unmask``
- irq_eoi() - Optional, required for EOI flow handlers
- ``irq_eoi`` - Optional, required for EOI flow handlers
- irq_retrigger() - Optional
- ``irq_retrigger`` - Optional
- irq_set_type() - Optional
- ``irq_set_type`` - Optional
- irq_set_wake() - Optional
- ``irq_set_wake`` - Optional
These primitives are strictly intended to mean what they say: ack means
ACK, masking means masking of an IRQ line, etc. It is up to the flow
......@@ -369,7 +369,7 @@ handler(s) to use these basic units of low-level functionality.
__do_IRQ entry point
====================
The original implementation __do_IRQ() was an alternative entry point
The original implementation :c:func:`__do_IRQ` was an alternative entry point
for all types of interrupts. It no longer exists.
This handler turned out to be not suitable for all interrupt hardware
......@@ -415,10 +415,8 @@ This chapter contains the autogenerated documentation of the kernel API
functions which are exported.
.. kernel-doc:: kernel/irq/manage.c
:export:
.. kernel-doc:: kernel/irq/chip.c
:export:
Internal Functions Provided
===========================
......@@ -427,13 +425,10 @@ This chapter contains the autogenerated documentation of the internal
functions.
.. kernel-doc:: kernel/irq/irqdesc.c
:internal:
.. kernel-doc:: kernel/irq/handle.c
:internal:
.. kernel-doc:: kernel/irq/chip.c
:internal:
Credits
=======
......
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