<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
<book id="Generic-IRQ-Guide">
<bookinfo>
<title>Linux generic IRQ handling</title>
<authorgroup>
<author>
<firstname>Thomas</firstname>
<surname>Gleixner</surname>
<affiliation>
<address>
<email>tglx@linutronix.de</email>
</address>
</affiliation>
</author>
<author>
<firstname>Ingo</firstname>
<surname>Molnar</surname>
<affiliation>
<address>
<email>mingo@elte.hu</email>
</address>
</affiliation>
</author>
</authorgroup>
<copyright>
<year>2005-2006</year>
<holder>Thomas Gleixner</holder>
</copyright>
<copyright>
<year>2005-2006</year>
<holder>Ingo Molnar</holder>
</copyright>
<legalnotice>
<para>
This documentation is free software; you can redistribute
it and/or modify it under the terms of the GNU General Public
License version 2 as published by the Free Software Foundation.
</para>
<para>
This program is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
</para>
<para>
You should have received a copy of the GNU General Public
License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
</para>
<para>
For more details see the file COPYING in the source
distribution of Linux.
</para>
</legalnotice>
</bookinfo>
<toc></toc>
<chapter id="intro">
<title>Introduction</title>
<para>
The generic interrupt handling layer is designed to provide a
complete abstraction of interrupt handling for device drivers.
It is able to handle all the different types of interrupt controller
hardware. Device drivers use generic API functions to request, enable,
disable and free interrupts. The drivers do not have to know anything
about interrupt hardware details, so they can be used on different
platforms without code changes.
</para>
<para>
This documentation is provided to developers who want to implement
an interrupt subsystem based for their architecture, with the help
of the generic IRQ handling layer.
</para>
</chapter>
<chapter id="rationale">
<title>Rationale</title>
<para>
The original implementation of interrupt handling in Linux is using
the __do_IRQ() super-handler, which is able to deal with every
type of interrupt logic.
</para>
<para>
Originally, Russell King identified different types of handlers to
build a quite universal set for the ARM interrupt handler
implementation in Linux 2.5/2.6. He distinguished between:
<itemizedlist>
<listitem><para>Level type</para></listitem>
<listitem><para>Edge type</para></listitem>
<listitem><para>Simple type</para></listitem>
</itemizedlist>
In the SMP world of the __do_IRQ() super-handler another type
was identified:
<itemizedlist>
<listitem><para>Per CPU type</para></listitem>
</itemizedlist>
</para>
<para>
This split implementation of highlevel IRQ handlers allows us to
optimize the flow of the interrupt handling for each specific
interrupt type. This reduces complexity in that particular codepath
and allows the optimized handling of a given type.
</para>
<para>
The original general IRQ implementation used hw_interrupt_type
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 lowlevel hardware logic, and it also leads
to unnecessary code duplication: for example in i386, there is a
ioapic_level_irq and a ioapic_edge_irq irq-type which share many
of the lowlevel details but have different flow handling.
</para>
<para>
A more natural abstraction is the clean separation of the
'irq flow' and the 'chip details'.
</para>
<para>
Analysing a couple of architecture's IRQ subsystem implementations
reveals that most of them can use a generic set of 'irq flow'
methods and only need to add the chip level specific code.
The separation is also valuable for (sub)architectures
which need specific quirks in the irq flow itself but not in the
chip-details - and thus provides a more transparent IRQ subsystem
design.
</para>
<para>
Each interrupt descriptor is assigned its own highlevel flow
handler, which is normally one of the generic
implementations. (This highlevel flow handler implementation also
makes it simple to provide demultiplexing handlers which can be
found in embedded platforms on various architectures.)
</para>
<para>
The separation makes the generic interrupt handling layer more
flexible and extensible. For example, an (sub)architecture can
use a generic irq-flow implementation for 'level type' interrupts
and add a (sub)architecture specific 'edge type' implementation.
</para>
<para>
To make the transition to the new model easier and prevent the
breakage of existing implementations, the __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.
</para>
</chapter>
<chapter id="bugs">
<title>Known Bugs And Assumptions</title>
<para>
None (knock on wood).
</para>
</chapter>
<chapter id="Abstraction">
<title>Abstraction layers</title>
<para>
There are three main levels of abstraction in the interrupt code:
<orderedlist>
<listitem><para>Highlevel driver API</para></listitem>
<listitem><para>Highlevel IRQ flow handlers</para></listitem>
<listitem><para>Chiplevel hardware encapsulation</para></listitem>
</orderedlist>
</para>
<sect1 id="Interrupt_control_flow">
<title>Interrupt control flow</title>
<para>
Each interrupt is described by an interrupt descriptor structure
irq_desc. The interrupt is referenced by an 'unsigned int' numeric
value which selects the corresponding interrupt decription structure
in the descriptor structures array.
The descriptor structure contains status information and pointers
to the interrupt flow method and the interrupt chip structure
which are assigned to this interrupt.
</para>
<para>
Whenever an interrupt triggers, the lowlevel arch code calls into
the generic interrupt code by calling desc->handle_irq().
This highlevel IRQ handling function only uses desc->chip primitives
referenced by the assigned chip descriptor structure.
</para>
</sect1>
<sect1 id="Highlevel_Driver_API">
<title>Highlevel Driver API</title>
<para>
The highlevel Driver API consists of following functions:
<itemizedlist>
<listitem><para>request_irq()</para></listitem>
<listitem><para>free_irq()</para></listitem>
<listitem><para>disable_irq()</para></listitem>
<listitem><para>enable_irq()</para></listitem>
<listitem><para>disable_irq_nosync() (SMP only)</para></listitem>
<listitem><para>synchronize_irq() (SMP only)</para></listitem>
<listitem><para>set_irq_type()</para></listitem>
<listitem><para>set_irq_wake()</para></listitem>
<listitem><para>set_irq_data()</para></listitem>
<listitem><para>set_irq_chip()</para></listitem>
<listitem><para>set_irq_chip_data()</para></listitem>
</itemizedlist>
See the autogenerated function documentation for details.
</para>
</sect1>
<sect1 id="Highlevel_IRQ_flow_handlers">
<title>Highlevel IRQ flow handlers</title>
<para>
The generic layer provides a set of pre-defined irq-flow methods:
<itemizedlist>
<listitem><para>handle_level_irq</para></listitem>
<listitem><para>handle_edge_irq</para></listitem>
<listitem><para>handle_simple_irq</para></listitem>
<listitem><para>handle_percpu_irq</para></listitem>
</itemizedlist>
The interrupt flow handlers (either predefined or architecture
specific) are assigned to specific interrupts by the architecture
either during bootup or during device initialization.
</para>
<sect2 id="Default_flow_implementations">
<title>Default flow implementations</title>
<sect3 id="Helper_functions">
<title>Helper functions</title>
<para>
The helper functions call the chip primitives and
are used by the default flow implementations.
The following helper functions are implemented (simplified excerpt):
<programlisting>
default_enable(irq)
{
desc->chip->unmask(irq);
}
default_disable(irq)
{
if (!delay_disable(irq))
desc->chip->mask(irq);
}
default_ack(irq)
{
chip->ack(irq);
}
default_mask_ack(irq)
{
if (chip->mask_ack) {
chip->mask_ack(irq);
} else {
chip->mask(irq);
chip->ack(irq);
}
}
noop(irq)
{
}
</programlisting>
</para>
</sect3>
</sect2>
<sect2 id="Default_flow_handler_implementations">
<title>Default flow handler implementations</title>
<sect3 id="Default_Level_IRQ_flow_handler">
<title>Default Level IRQ flow handler</title>
<para>
handle_level_irq provides a generic implementation
for level-triggered interrupts.
</para>
<para>
The following control flow is implemented (simplified excerpt):
<programlisting>
desc->chip->start();
handle_IRQ_event(desc->action);
desc->chip->end();
</programlisting>
</para>
</sect3>
<sect3 id="Default_Edge_IRQ_flow_handler">
<title>Default Edge IRQ flow handler</title>
<para>
handle_edge_irq provides a generic implementation
for edge-triggered interrupts.
</para>
<para>
The following control flow is implemented (simplified excerpt):
<programlisting>
if (desc->status & running) {
desc->chip->hold();
desc->status |= pending | masked;
return;
}
desc->chip->start();
desc->status |= running;
do {
if (desc->status & masked)
desc->chip->enable();
desc->status &= ~pending;
handle_IRQ_event(desc->action);
} while (status & pending);
desc->status &= ~running;
desc->chip->end();
</programlisting>
</para>
</sect3>
<sect3 id="Default_simple_IRQ_flow_handler">
<title>Default simple IRQ flow handler</title>
<para>
handle_simple_irq provides a generic implementation
for simple interrupts.
</para>
<para>
Note: The simple flow handler does not call any
handler/chip primitives.
</para>
<para>
The following control flow is implemented (simplified excerpt):
<programlisting>
handle_IRQ_event(desc->action);
</programlisting>
</para>
</sect3>
<sect3 id="Default_per_CPU_flow_handler">
<title>Default per CPU flow handler</title>
<para>
handle_percpu_irq provides a generic implementation
for per CPU interrupts.
</para>
<para>
Per CPU interrupts are only available on SMP and
the handler provides a simplified version without
locking.
</para>
<para>
The following control flow is implemented (simplified excerpt):
<programlisting>
desc->chip->start();
handle_IRQ_event(desc->action);
desc->chip->end();
</programlisting>
</para>
</sect3>
</sect2>
<sect2 id="Quirks_and_optimizations">
<title>Quirks and optimizations</title>
<para>
The generic functions are intended for 'clean' architectures and chips,
which have no platform-specific IRQ handling quirks. If an architecture
needs to implement quirks on the 'flow' level then it can do so by
overriding the highlevel irq-flow handler.
</para>
</sect2>
<sect2 id="Delayed_interrupt_disable">
<title>Delayed interrupt disable</title>
<para>
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 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 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 of retriggering an interrupt.)
The delayed interrupt disable can be runtime enabled, per interrupt,
by setting the IRQ_DELAYED_DISABLE flag in the irq_desc status field.
</para>
</sect2>
</sect1>
<sect1 id="Chiplevel_hardware_encapsulation">
<title>Chiplevel hardware encapsulation</title>
<para>
The chip level hardware descriptor structure irq_chip
contains all the direct chip relevant functions, which
can be utilized by the irq flow implementations.
<itemizedlist>
<listitem><para>ack()</para></listitem>
<listitem><para>mask_ack() - Optional, recommended for performance</para></listitem>
<listitem><para>mask()</para></listitem>
<listitem><para>unmask()</para></listitem>
<listitem><para>retrigger() - Optional</para></listitem>
<listitem><para>set_type() - Optional</para></listitem>
<listitem><para>set_wake() - Optional</para></listitem>
</itemizedlist>
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
handler(s) to use these basic units of lowlevel functionality.
</para>
</sect1>
</chapter>
<chapter id="doirq">
<title>__do_IRQ entry point</title>
<para>
The original implementation __do_IRQ() is an alternative entry
point for all types of interrupts.
</para>
<para>
This handler turned out to be not suitable for all
interrupt hardware and was therefore reimplemented with split
functionality for egde/level/simple/percpu interrupts. This is not
only a functional optimization. It also shortens code paths for
interrupts.
</para>
<para>
To make use of the split implementation, replace the call to
__do_IRQ by a call to desc->chip->handle_irq() and associate
the appropriate handler function to desc->chip->handle_irq().
In most cases the generic handler implementations should
be sufficient.
</para>
</chapter>
<chapter id="locking">
<title>Locking on SMP</title>
<para>
The locking of chip registers is up to the architecture that
defines the chip primitives. There is a chip->lock field that can be used
for serialization, but the generic layer does not touch it. The per-irq
structure is protected via desc->lock, by the generic layer.
</para>
</chapter>
<chapter id="structs">
<title>Structures</title>
<para>
This chapter contains the autogenerated documentation of the structures which are
used in the generic IRQ layer.
</para>
<!-- include/linux/irq.h -->
<refentry id="API-struct-irq-chip">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>struct irq_chip</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>struct irq_chip</refname>
<refpurpose>
hardware interrupt chip descriptor
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<programlisting>
struct irq_chip {
const char * name;
unsigned int (* startup) (unsigned int irq);
void (* shutdown) (unsigned int irq);
void (* enable) (unsigned int irq);
void (* disable) (unsigned int irq);
void (* ack) (unsigned int irq);
void (* mask) (unsigned int irq);
void (* mask_ack) (unsigned int irq);
void (* unmask) (unsigned int irq);
void (* eoi) (unsigned int irq);
void (* end) (unsigned int irq);
int (* set_affinity) (unsigned int irq,const struct cpumask *dest);
int (* retrigger) (unsigned int irq);
int (* set_type) (unsigned int irq, unsigned int flow_type);
int (* set_wake) (unsigned int irq, unsigned int on);
void (* bus_lock) (unsigned int irq);
void (* bus_sync_unlock) (unsigned int irq);
#ifdef CONFIG_IRQ_RELEASE_METHOD
void (* release) (unsigned int irq, void *dev_id);
#endif
const char * typename;
}; </programlisting>
</refsynopsisdiv>
<refsect1>
<title>Members</title>
<variablelist>
<varlistentry> <term>name</term>
<listitem><para>
name for /proc/interrupts
</para></listitem>
</varlistentry>
<varlistentry> <term>startup</term>
<listitem><para>
start up the interrupt (defaults to ->enable if NULL)
</para></listitem>
</varlistentry>
<varlistentry> <term>shutdown</term>
<listitem><para>
shut down the interrupt (defaults to ->disable if NULL)
</para></listitem>
</varlistentry>
<varlistentry> <term>enable</term>
<listitem><para>
enable the interrupt (defaults to chip->unmask if NULL)
</para></listitem>
</varlistentry>
<varlistentry> <term>disable</term>
<listitem><para>
disable the interrupt (defaults to chip->mask if NULL)
</para></listitem>
</varlistentry>
<varlistentry> <term>ack</term>
<listitem><para>
start of a new interrupt
</para></listitem>
</varlistentry>
<varlistentry> <term>mask</term>
<listitem><para>
mask an interrupt source
</para></listitem>
</varlistentry>
<varlistentry> <term>mask_ack</term>
<listitem><para>
ack and mask an interrupt source
</para></listitem>
</varlistentry>
<varlistentry> <term>unmask</term>
<listitem><para>
unmask an interrupt source
</para></listitem>
</varlistentry>
<varlistentry> <term>eoi</term>
<listitem><para>
end of interrupt - chip level
</para></listitem>
</varlistentry>
<varlistentry> <term>end</term>
<listitem><para>
end of interrupt - flow level
</para></listitem>
</varlistentry>
<varlistentry> <term>set_affinity</term>
<listitem><para>
set the CPU affinity on SMP machines
</para></listitem>
</varlistentry>
<varlistentry> <term>retrigger</term>
<listitem><para>
resend an IRQ to the CPU
</para></listitem>
</varlistentry>
<varlistentry> <term>set_type</term>
<listitem><para>
set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ
</para></listitem>
</varlistentry>
<varlistentry> <term>set_wake</term>
<listitem><para>
enable/disable power-management wake-on of an IRQ
</para></listitem>
</varlistentry>
<varlistentry> <term>bus_lock</term>
<listitem><para>
function to lock access to slow bus (i2c) chips
</para></listitem>
</varlistentry>
<varlistentry> <term>bus_sync_unlock</term>
<listitem><para>
function to sync and unlock slow bus (i2c) chips
</para></listitem>
</varlistentry>
<varlistentry> <term>release</term>
<listitem><para>
release function solely used by UML
</para></listitem>
</varlistentry>
<varlistentry> <term>typename</term>
<listitem><para>
obsoleted by name, kept as migration helper
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
<refentry id="API-struct-irq-desc">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>struct irq_desc</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>struct irq_desc</refname>
<refpurpose>
interrupt descriptor
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<programlisting>
struct irq_desc {
unsigned int irq;
struct timer_rand_state * timer_rand_state;
unsigned int * kstat_irqs;
#ifdef CONFIG_INTR_REMAP
struct irq_2_iommu * irq_2_iommu;
#endif
irq_flow_handler_t handle_irq;
struct irq_chip * chip;
struct msi_desc * msi_desc;
void * handler_data;
void * chip_data;
struct irqaction * action;
unsigned int status;
unsigned int depth;
unsigned int wake_depth;
unsigned int irq_count;
unsigned long last_unhandled;
unsigned int irqs_unhandled;
spinlock_t lock;
#ifdef CONFIG_SMP
cpumask_var_t affinity;
unsigned int node;
#ifdef CONFIG_GENERIC_PENDING_IRQ
cpumask_var_t pending_mask;
#endif
#endif
atomic_t threads_active;
wait_queue_head_t wait_for_threads;
#ifdef CONFIG_PROC_FS
struct proc_dir_entry * dir;
#endif
const char * name;
}; </programlisting>
</refsynopsisdiv>
<refsect1>
<title>Members</title>
<variablelist>
<varlistentry> <term>irq</term>
<listitem><para>
interrupt number for this descriptor
</para></listitem>
</varlistentry>
<varlistentry> <term>timer_rand_state</term>
<listitem><para>
pointer to timer rand state struct
</para></listitem>
</varlistentry>
<varlistentry> <term>kstat_irqs</term>
<listitem><para>
irq stats per cpu
</para></listitem>
</varlistentry>
<varlistentry> <term>irq_2_iommu</term>
<listitem><para>
iommu with this irq
</para></listitem>
</varlistentry>
<varlistentry> <term>handle_irq</term>
<listitem><para>
highlevel irq-events handler [if NULL, <function>__do_IRQ</function>]
</para></listitem>
</varlistentry>
<varlistentry> <term>chip</term>
<listitem><para>
low level interrupt hardware access
</para></listitem>
</varlistentry>
<varlistentry> <term>msi_desc</term>
<listitem><para>
MSI descriptor
</para></listitem>
</varlistentry>
<varlistentry> <term>handler_data</term>
<listitem><para>
per-IRQ data for the irq_chip methods
</para></listitem>
</varlistentry>
<varlistentry> <term>chip_data</term>
<listitem><para>
platform-specific per-chip private data for the chip
methods, to allow shared chip implementations
</para></listitem>
</varlistentry>
<varlistentry> <term>action</term>
<listitem><para>
the irq action chain
</para></listitem>
</varlistentry>
<varlistentry> <term>status</term>
<listitem><para>
status information
</para></listitem>
</varlistentry>
<varlistentry> <term>depth</term>
<listitem><para>
disable-depth, for nested <function>irq_disable</function> calls
</para></listitem>
</varlistentry>
<varlistentry> <term>wake_depth</term>
<listitem><para>
enable depth, for multiple <function>set_irq_wake</function> callers
</para></listitem>
</varlistentry>
<varlistentry> <term>irq_count</term>
<listitem><para>
stats field to detect stalled irqs
</para></listitem>
</varlistentry>
<varlistentry> <term>last_unhandled</term>
<listitem><para>
aging timer for unhandled count
</para></listitem>
</varlistentry>
<varlistentry> <term>irqs_unhandled</term>
<listitem><para>
stats field for spurious unhandled interrupts
</para></listitem>
</varlistentry>
<varlistentry> <term>lock</term>
<listitem><para>
locking for SMP
</para></listitem>
</varlistentry>
<varlistentry> <term>affinity</term>
<listitem><para>
IRQ affinity on SMP
</para></listitem>
</varlistentry>
<varlistentry> <term>node</term>
<listitem><para>
node index useful for balancing
</para></listitem>
</varlistentry>
<varlistentry> <term>pending_mask</term>
<listitem><para>
pending rebalanced interrupts
</para></listitem>
</varlistentry>
<varlistentry> <term>threads_active</term>
<listitem><para>
number of irqaction threads currently running
</para></listitem>
</varlistentry>
<varlistentry> <term>wait_for_threads</term>
<listitem><para>
wait queue for sync_irq to wait for threaded handlers
</para></listitem>
</varlistentry>
<varlistentry> <term>dir</term>
<listitem><para>
/proc/irq/ procfs entry
</para></listitem>
</varlistentry>
<varlistentry> <term>name</term>
<listitem><para>
flow handler name for /proc/interrupts output
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
<refentry id="API-alloc-desc-masks">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>alloc_desc_masks</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>alloc_desc_masks</refname>
<refpurpose>
allocate cpumasks for irq_desc
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>bool <function>alloc_desc_masks </function></funcdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
<paramdef>int <parameter>node</parameter></paramdef>
<paramdef>bool <parameter>boot</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
pointer to irq_desc struct
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>node</parameter></term>
<listitem>
<para>
node which will be handling the cpumasks
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>boot</parameter></term>
<listitem>
<para>
true if need bootmem
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Allocates affinity and pending_mask cpumask if required.
Returns true if successful (or not required).
</para>
</refsect1>
</refentry>
<refentry id="API-init-copy-desc-masks">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>init_copy_desc_masks</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>init_copy_desc_masks</refname>
<refpurpose>
copy cpumasks for irq_desc
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>init_copy_desc_masks </function></funcdef>
<paramdef>struct irq_desc * <parameter>old_desc</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>new_desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>old_desc</parameter></term>
<listitem>
<para>
pointer to old irq_desc struct
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>new_desc</parameter></term>
<listitem>
<para>
pointer to new irq_desc struct
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Insures affinity and pending_masks are copied to new irq_desc.
If !CONFIG_CPUMASKS_OFFSTACK the cpumasks are embedded in the
irq_desc struct so the copy is redundant.
</para>
</refsect1>
</refentry>
<!-- include/linux/interrupt.h -->
<refentry id="API-struct-irqaction">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>struct irqaction</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>struct irqaction</refname>
<refpurpose>
per interrupt action descriptor
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<programlisting>
struct irqaction {
irq_handler_t handler;
unsigned long flags;
const char * name;
void * dev_id;
struct irqaction * next;
int irq;
struct proc_dir_entry * dir;
irq_handler_t thread_fn;
struct task_struct * thread;
unsigned long thread_flags;
}; </programlisting>
</refsynopsisdiv>
<refsect1>
<title>Members</title>
<variablelist>
<varlistentry> <term>handler</term>
<listitem><para>
interrupt handler function
</para></listitem>
</varlistentry>
<varlistentry> <term>flags</term>
<listitem><para>
flags (see IRQF_* above)
</para></listitem>
</varlistentry>
<varlistentry> <term>name</term>
<listitem><para>
name of the device
</para></listitem>
</varlistentry>
<varlistentry> <term>dev_id</term>
<listitem><para>
cookie to identify the device
</para></listitem>
</varlistentry>
<varlistentry> <term>next</term>
<listitem><para>
pointer to the next irqaction for shared interrupts
</para></listitem>
</varlistentry>
<varlistentry> <term>irq</term>
<listitem><para>
interrupt number
</para></listitem>
</varlistentry>
<varlistentry> <term>dir</term>
<listitem><para>
pointer to the proc/irq/NN/name entry
</para></listitem>
</varlistentry>
<varlistentry> <term>thread_fn</term>
<listitem><para>
interupt handler function for threaded interrupts
</para></listitem>
</varlistentry>
<varlistentry> <term>thread</term>
<listitem><para>
thread pointer for threaded interrupts
</para></listitem>
</varlistentry>
<varlistentry> <term>thread_flags</term>
<listitem><para>
flags related to <parameter>thread</parameter>
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
</chapter>
<chapter id="pubfunctions">
<title>Public Functions Provided</title>
<para>
This chapter contains the autogenerated documentation of the kernel API functions
which are exported.
</para>
<!-- kernel/irq/manage.c -->
<refentry id="API-synchronize-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>synchronize_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>synchronize_irq</refname>
<refpurpose>
wait for pending IRQ handlers (on other CPUs)
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>synchronize_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
interrupt number to wait for
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
This function waits for any pending IRQ handlers for this interrupt
to complete before returning. If you use this function while
holding a resource the IRQ handler may need you will deadlock.
</para><para>
This function may be called - with care - from IRQ context.
</para>
</refsect1>
</refentry>
<refentry id="API-disable-irq-nosync">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>disable_irq_nosync</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>disable_irq_nosync</refname>
<refpurpose>
disable an irq without waiting
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>disable_irq_nosync </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt to disable
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Disable the selected interrupt line. Disables and Enables are
nested.
Unlike <function>disable_irq</function>, this function does not ensure existing
instances of the IRQ handler have completed before returning.
</para><para>
This function may be called from IRQ context.
</para>
</refsect1>
</refentry>
<refentry id="API-disable-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>disable_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>disable_irq</refname>
<refpurpose>
disable an irq and wait for completion
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>disable_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt to disable
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Disable the selected interrupt line. Enables and Disables are
nested.
This function waits for any pending IRQ handlers for this interrupt
to complete before returning. If you use this function while
holding a resource the IRQ handler may need you will deadlock.
</para><para>
This function may be called - with care - from IRQ context.
</para>
</refsect1>
</refentry>
<refentry id="API-enable-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>enable_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>enable_irq</refname>
<refpurpose>
enable handling of an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>enable_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt to enable
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Undoes the effect of one call to <function>disable_irq</function>. If this
matches the last disable, processing of interrupts on this
IRQ line is re-enabled.
</para><para>
This function may be called from IRQ context only when
desc->chip->bus_lock and desc->chip->bus_sync_unlock are NULL !
</para>
</refsect1>
</refentry>
<refentry id="API-set-irq-wake">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_wake</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_wake</refname>
<refpurpose>
control irq power management wakeup
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>set_irq_wake </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>unsigned int <parameter>on</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
interrupt to control
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>on</parameter></term>
<listitem>
<para>
enable/disable power management wakeup
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Enable/disable power management wakeup mode, which is
disabled by default. Enables and disables must match,
just as they match for non-wakeup mode support.
</para><para>
Wakeup mode lets this IRQ wake the system from sleep
states like <quote>suspend to RAM</quote>.
</para>
</refsect1>
</refentry>
<refentry id="API-setup-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>setup_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>setup_irq</refname>
<refpurpose>
setup an interrupt
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>setup_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irqaction * <parameter>act</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt line to setup
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>act</parameter></term>
<listitem>
<para>
irqaction for the interrupt
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Used to statically setup interrupts in the early boot process.
</para>
</refsect1>
</refentry>
<refentry id="API-remove-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>remove_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>remove_irq</refname>
<refpurpose>
free an interrupt
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>remove_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irqaction * <parameter>act</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt line to free
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>act</parameter></term>
<listitem>
<para>
irqaction for the interrupt
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Used to remove interrupts statically setup by the early boot process.
</para>
</refsect1>
</refentry>
<refentry id="API-free-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>free_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>free_irq</refname>
<refpurpose>
free an interrupt allocated with request_irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>free_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>void * <parameter>dev_id</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt line to free
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>dev_id</parameter></term>
<listitem>
<para>
Device identity to free
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Remove an interrupt handler. The handler is removed and if the
interrupt line is no longer in use by any driver it is disabled.
On a shared IRQ the caller must ensure the interrupt is disabled
on the card it drives before calling this function. The function
does not return until any executing interrupts for this IRQ
have completed.
</para><para>
This function must not be called from interrupt context.
</para>
</refsect1>
</refentry>
<refentry id="API-request-threaded-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>request_threaded_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>request_threaded_irq</refname>
<refpurpose>
allocate an interrupt line
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>request_threaded_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>irq_handler_t <parameter>handler</parameter></paramdef>
<paramdef>irq_handler_t <parameter>thread_fn</parameter></paramdef>
<paramdef>unsigned long <parameter>irqflags</parameter></paramdef>
<paramdef>const char * <parameter>devname</parameter></paramdef>
<paramdef>void * <parameter>dev_id</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt line to allocate
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>handler</parameter></term>
<listitem>
<para>
Function to be called when the IRQ occurs.
Primary handler for threaded interrupts
If NULL and thread_fn != NULL the default
primary handler is installed
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>thread_fn</parameter></term>
<listitem>
<para>
Function called from the irq handler thread
If NULL, no irq thread is created
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>irqflags</parameter></term>
<listitem>
<para>
Interrupt type flags
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>devname</parameter></term>
<listitem>
<para>
An ascii name for the claiming device
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>dev_id</parameter></term>
<listitem>
<para>
A cookie passed back to the handler function
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
This call allocates interrupt resources and enables the
interrupt line and IRQ handling. From the point this
call is made your handler function may be invoked. Since
your handler function must clear any interrupt the board
raises, you must take care both to initialise your hardware
and to set up the interrupt handler in the right order.
</para><para>
If you want to set up a threaded irq handler for your device
then you need to supply <parameter>handler</parameter> and <parameter>thread_fn</parameter>. <parameter>handler</parameter> ist
still called in hard interrupt context and has to check
whether the interrupt originates from the device. If yes it
needs to disable the interrupt on the device and return
IRQ_WAKE_THREAD which will wake up the handler thread and run
<parameter>thread_fn</parameter>. This split handler design is necessary to support
shared interrupts.
</para><para>
Dev_id must be globally unique. Normally the address of the
device data structure is used as the cookie. Since the handler
receives this value it makes sense to use it.
</para><para>
If your interrupt is shared you must pass a non NULL dev_id
as this is required when freeing the interrupt.
</para>
</refsect1>
<refsect1>
<title>Flags</title>
<para>
</para><para>
IRQF_SHARED Interrupt is shared
IRQF_DISABLED Disable local interrupts while processing
IRQF_SAMPLE_RANDOM The interrupt can be used for entropy
IRQF_TRIGGER_* Specify active edge(s) or level
</para>
</refsect1>
</refentry>
<!-- kernel/irq/chip.c -->
<refentry id="API-set-irq-chip">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_chip</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_chip</refname>
<refpurpose>
set the irq chip for an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>set_irq_chip </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_chip * <parameter>chip</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
irq number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>chip</parameter></term>
<listitem>
<para>
pointer to irq chip description structure
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
<refentry id="API-set-irq-type">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_type</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_type</refname>
<refpurpose>
set the irq trigger type for an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>set_irq_type </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>unsigned int <parameter>type</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
irq number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>type</parameter></term>
<listitem>
<para>
IRQ_TYPE_{LEVEL,EDGE}_* value - see include/linux/irq.h
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
<refentry id="API-set-irq-data">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_data</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_data</refname>
<refpurpose>
set irq type data for an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>set_irq_data </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>void * <parameter>data</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>data</parameter></term>
<listitem>
<para>
Pointer to interrupt specific data
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Set the hardware irq controller data for an irq
</para>
</refsect1>
</refentry>
<refentry id="API-set-irq-chip-data">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_chip_data</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_chip_data</refname>
<refpurpose>
set irq chip data for an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>set_irq_chip_data </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>void * <parameter>data</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>data</parameter></term>
<listitem>
<para>
Pointer to chip specific data
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Set the hardware irq chip data for an irq
</para>
</refsect1>
</refentry>
<refentry id="API-set-irq-nested-thread">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_nested_thread</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_nested_thread</refname>
<refpurpose>
Set/Reset the IRQ_NESTED_THREAD flag of an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>set_irq_nested_thread </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>int <parameter>nest</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>nest</parameter></term>
<listitem>
<para>
0 to clear / 1 to set the IRQ_NESTED_THREAD flag
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
The IRQ_NESTED_THREAD flag indicates that on
<function>request_threaded_irq</function> no separate interrupt thread should be
created for the irq as the handler are called nested in the
context of a demultiplexing interrupt handler thread.
</para>
</refsect1>
</refentry>
<refentry id="API-handle-level-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_level_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_level_irq</refname>
<refpurpose>
Level type irq handler
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>handle_level_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
the interrupt description structure for this irq
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Level type interrupts are active as long as the hardware line has
the active level. This may require to mask the interrupt and unmask
it after the associated handler has acknowledged the device, so the
interrupt line is back to inactive.
</para>
</refsect1>
</refentry>
</chapter>
<chapter id="intfunctions">
<title>Internal Functions Provided</title>
<para>
This chapter contains the autogenerated documentation of the internal functions.
</para>
<!-- kernel/irq/handle.c -->
<refentry id="API-handle-bad-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_bad_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_bad_irq</refname>
<refpurpose>
handle spurious and unhandled irqs
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>handle_bad_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
description of the interrupt
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Handles spurious and unhandled IRQ's. It also prints a debugmessage.
</para>
</refsect1>
</refentry>
<refentry id="API-handle-IRQ-event">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_IRQ_event</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_IRQ_event</refname>
<refpurpose>
irq action chain handler
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>irqreturn_t <function>handle_IRQ_event </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irqaction * <parameter>action</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>action</parameter></term>
<listitem>
<para>
the interrupt action chain for this irq
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Handles the action chain of an irq event
</para>
</refsect1>
</refentry>
<refentry id="API---do-IRQ">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>__do_IRQ</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>__do_IRQ</refname>
<refpurpose>
original all in one highlevel IRQ handler
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>unsigned int <function>__do_IRQ </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
__do_IRQ handles all normal device IRQ's (the special
SMP cross-CPU interrupts have their own specific
handlers).
</para><para>
This is the original x86 implementation which is used for every
interrupt type.
</para>
</refsect1>
</refentry>
<!-- kernel/irq/chip.c -->
<refentry id="API-dynamic-irq-init">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>dynamic_irq_init</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>dynamic_irq_init</refname>
<refpurpose>
initialize a dynamically allocated irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>dynamic_irq_init </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
irq number to initialize
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
<refentry id="API-dynamic-irq-init-keep-chip-data">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>dynamic_irq_init_keep_chip_data</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>dynamic_irq_init_keep_chip_data</refname>
<refpurpose>
initialize a dynamically allocated irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>dynamic_irq_init_keep_chip_data </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
irq number to initialize
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
does not set irq_to_desc(irq)->chip_data to NULL
</para>
</refsect1>
</refentry>
<refentry id="API-dynamic-irq-cleanup">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>dynamic_irq_cleanup</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>dynamic_irq_cleanup</refname>
<refpurpose>
cleanup a dynamically allocated irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>dynamic_irq_cleanup </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
irq number to initialize
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
<refentry id="API-dynamic-irq-cleanup-keep-chip-data">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>dynamic_irq_cleanup_keep_chip_data</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>dynamic_irq_cleanup_keep_chip_data</refname>
<refpurpose>
cleanup a dynamically allocated irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>dynamic_irq_cleanup_keep_chip_data </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
irq number to initialize
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
does not set irq_to_desc(irq)->chip_data to NULL
</para>
</refsect1>
</refentry>
<refentry id="API-set-irq-msi">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>set_irq_msi</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>set_irq_msi</refname>
<refpurpose>
set irq type data for an irq
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>int <function>set_irq_msi </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct msi_desc * <parameter>entry</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
Interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>entry</parameter></term>
<listitem>
<para>
Pointer to MSI descriptor data
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Set the hardware irq controller data for an irq
</para>
</refsect1>
</refentry>
<refentry id="API-handle-simple-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_simple_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_simple_irq</refname>
<refpurpose>
Simple and software-decoded IRQs.
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>handle_simple_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
the interrupt description structure for this irq
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Simple interrupts are either sent from a demultiplexing interrupt
handler or come from hardware, where no interrupt hardware control
is necessary.
</para>
</refsect1>
<refsect1>
<title>Note</title>
<para>
The caller is expected to handle the ack, clear, mask and
unmask issues if necessary.
</para>
</refsect1>
</refentry>
<refentry id="API-handle-fasteoi-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_fasteoi_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_fasteoi_irq</refname>
<refpurpose>
irq handler for transparent controllers
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>handle_fasteoi_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
the interrupt description structure for this irq
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Only a single callback will be issued to the chip</title>
<para>
an -><function>eoi</function>
call when the interrupt has been serviced. This enables support
for modern forms of interrupt handlers, which handle the flow
details in hardware, transparently.
</para>
</refsect1>
</refentry>
<refentry id="API-handle-edge-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_edge_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_edge_irq</refname>
<refpurpose>
edge type IRQ handler
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>handle_edge_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
the interrupt description structure for this irq
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Interrupt occures on the falling and/or rising edge of a hardware
signal. The occurence is latched into the irq controller hardware
and must be acked in order to be reenabled. After the ack another
interrupt can happen on the same source even before the first one
is handled by the assosiacted event handler. If this happens it
might be necessary to disable (mask) the interrupt depending on the
controller hardware. This requires to reenable the interrupt inside
of the loop which handles the interrupts which have arrived while
the handler was running. If all pending interrupts are handled, the
loop is left.
</para>
</refsect1>
</refentry>
<refentry id="API-handle-percpu-irq">
<refentryinfo>
<title>LINUX</title>
<productname>Kernel Hackers Manual</productname>
<date>October 2011</date>
</refentryinfo>
<refmeta>
<refentrytitle><phrase>handle_percpu_irq</phrase></refentrytitle>
<manvolnum>9</manvolnum>
<refmiscinfo class="version">2.6.32</refmiscinfo>
</refmeta>
<refnamediv>
<refname>handle_percpu_irq</refname>
<refpurpose>
Per CPU local irq handler
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Synopsis</title>
<funcsynopsis><funcprototype>
<funcdef>void <function>handle_percpu_irq </function></funcdef>
<paramdef>unsigned int <parameter>irq</parameter></paramdef>
<paramdef>struct irq_desc * <parameter>desc</parameter></paramdef>
</funcprototype></funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>irq</parameter></term>
<listitem>
<para>
the interrupt number
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>desc</parameter></term>
<listitem>
<para>
the interrupt description structure for this irq
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Description</title>
<para>
Per CPU interrupts on SMP machines without locking requirements
</para>
</refsect1>
</refentry>
</chapter>
<chapter id="credits">
<title>Credits</title>
<para>
The following people have contributed to this document:
<orderedlist>
<listitem><para>Thomas Gleixner<email>tglx@linutronix.de</email></para></listitem>
<listitem><para>Ingo Molnar<email>mingo@elte.hu</email></para></listitem>
</orderedlist>
</para>
</chapter>
</book>
