Linux generic IRQ handling

Copyright

© 2005-2010: Thomas Gleixner

Copyright

© 2005-2006: Ingo Molnar

Introduction

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.

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.

Rationale

The original implementation of interrupt handling in Linux uses the __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 a quite universal set for the ARM interrupt handler implementation in Linux 2.5/2.6. He distinguished between:

  • Level type

  • Edge type

  • Simple type

During the implementation we identified another type:

  • Fast EOI type

In the SMP world of the __do_IRQ() super-handler another type was identified:

  • Per CPU type

This split implementation of high-level IRQ handlers allows us to optimize the flow of the interrupt handling for each specific interrupt 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 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 have different flow handling.

A more natural abstraction is the clean separation of the 'irq flow' and the 'chip details'.

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.

Each interrupt descriptor is assigned its own high-level flow handler, which is normally one of the generic implementations. (This high-level flow handler implementation also makes it simple to provide demultiplexing handlers which can be found in embedded platforms on various architectures.)

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.

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. It's deprecated for three years now and about to be removed.

Known Bugs And Assumptions

None (knock on wood).

Abstraction layers

There are three main levels of abstraction in the interrupt code:

  1. High-level driver API

  2. High-level IRQ flow handlers

  3. Chip-level hardware encapsulation

Interrupt control flow

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 description 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.

Whenever an interrupt triggers, the low-level architecture code calls into the generic interrupt code by calling desc->handle_irq(). This high-level IRQ handling function only uses desc->irq_data.chip primitives referenced by the assigned chip descriptor structure.

High-level Driver API

The high-level Driver API consists of following functions:

See the autogenerated function documentation for details.

High-level IRQ flow handlers

The generic layer provides a set of pre-defined irq-flow methods:

The interrupt flow handlers (either pre-defined or architecture specific) are assigned to specific interrupts by the architecture either during bootup or during device initialization.

Default flow implementations

Helper functions

The helper functions call the chip primitives and are used by the default flow implementations. The following helper functions are implemented (simplified excerpt):

default_enable(struct irq_data *data)
{
    desc->irq_data.chip->irq_unmask(data);
}

default_disable(struct irq_data *data)
{
    if (!delay_disable(data))
        desc->irq_data.chip->irq_mask(data);
}

default_ack(struct irq_data *data)
{
    chip->irq_ack(data);
}

default_mask_ack(struct irq_data *data)
{
    if (chip->irq_mask_ack) {
        chip->irq_mask_ack(data);
    } else {
        chip->irq_mask(data);
        chip->irq_ack(data);
    }
}

noop(struct irq_data *data))
{
}

Default flow handler implementations

Default Level IRQ flow handler

handle_level_irq provides a generic implementation for level-triggered interrupts.

The following control flow is implemented (simplified excerpt):

desc->irq_data.chip->irq_mask_ack();
handle_irq_event(desc->action);
desc->irq_data.chip->irq_unmask();
Default Fast EOI IRQ flow handler

handle_fasteoi_irq provides a generic implementation for interrupts, 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();
Default Edge IRQ flow handler

handle_edge_irq provides a generic implementation for edge-triggered interrupts.

The following control flow is implemented (simplified excerpt):

if (desc->status & running) {
    desc->irq_data.chip->irq_mask_ack();
    desc->status |= pending | masked;
    return;
}
desc->irq_data.chip->irq_ack();
desc->status |= running;
do {
    if (desc->status & masked)
        desc->irq_data.chip->irq_unmask();
    desc->status &= ~pending;
    handle_irq_event(desc->action);
} while (status & pending);
desc->status &= ~running;
Default simple IRQ flow handler

handle_simple_irq provides a generic implementation for simple interrupts.

注釈

The simple flow handler does not call any handler/chip primitives.

The following control flow is implemented (simplified excerpt):

handle_irq_event(desc->action);
Default per CPU flow handler

handle_percpu_irq provides a generic implementation for per CPU interrupts.

Per CPU interrupts are only available on SMP and the handler provides a 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();
handle_irq_event(desc->action);
if (desc->irq_data.chip->irq_eoi)
    desc->irq_data.chip->irq_eoi();
EOI Edge IRQ flow handler

handle_edge_eoi_irq provides an abnomination of the edge handler which is solely used to tame a badly wreckaged irq controller on powerpc/cell.

Bad IRQ flow handler

handle_bad_irq is used for spurious interrupts which have no real handler assigned..

Quirks and optimizations

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 high-level irq-flow handler.

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 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 is not 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 implementations.

  • irq_ack

  • irq_mask_ack - Optional, recommended for performance

  • irq_mask

  • irq_unmask

  • irq_eoi - Optional, required for EOI flow handlers

  • irq_retrigger - Optional

  • irq_set_type - 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 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 for all types of interrupts. It no longer exists.

This handler turned out to be not suitable for all interrupt hardware and was therefore reimplemented with split functionality for edge/level/simple/percpu interrupts. This is not only a functional optimization. It also shortens code paths for interrupts.

Locking on SMP

The locking of chip registers is up to the architecture that defines the chip primitives. The per-irq structure is protected via desc->lock, by the generic layer.

Generic interrupt chip

To avoid copies of identical implementations of IRQ chips the core provides a configurable generic interrupt chip implementation. Developers should check carefully whether the generic chip fits their needs before implementing the same functionality slightly differently themselves.

void irq_gc_mask_set_bit(struct irq_data * d)

Mask chip via setting bit in mask register

Parameters

struct irq_data * d

irq_data

Description

Chip has a single mask register. Values of this register are cached and protected by gc->lock

void irq_gc_mask_clr_bit(struct irq_data * d)

Mask chip via clearing bit in mask register

Parameters

struct irq_data * d

irq_data

Description

Chip has a single mask register. Values of this register are cached and protected by gc->lock

void irq_gc_ack_set_bit(struct irq_data * d)

Ack pending interrupt via setting bit

Parameters

struct irq_data * d

irq_data

struct irq_chip_generic * irq_alloc_generic_chip(const char * name, int num_ct, unsigned int irq_base, void __iomem * reg_base, irq_flow_handler_t handler)

Allocate a generic chip and initialize it

Parameters

const char * name

Name of the irq chip

int num_ct

Number of irq_chip_type instances associated with this

unsigned int irq_base

Interrupt base nr for this chip

void __iomem * reg_base

Register base address (virtual)

irq_flow_handler_t handler

Default flow handler associated with this chip

Description

Returns an initialized irq_chip_generic structure. The chip defaults to the primary (index 0) irq_chip_type and handler

int __irq_alloc_domain_generic_chips(struct irq_domain * d, int irqs_per_chip, int num_ct, const char * name, irq_flow_handler_t handler, unsigned int clr, unsigned int set, enum irq_gc_flags gcflags)

Allocate generic chips for an irq domain

Parameters

struct irq_domain * d

irq domain for which to allocate chips

int irqs_per_chip

Number of interrupts each chip handles (max 32)

int num_ct

Number of irq_chip_type instances associated with this

const char * name

Name of the irq chip

irq_flow_handler_t handler

Default flow handler associated with these chips

unsigned int clr

IRQ_* bits to clear in the mapping function

unsigned int set

IRQ_* bits to set in the mapping function

enum irq_gc_flags gcflags

Generic chip specific setup flags

struct irq_chip_generic * irq_get_domain_generic_chip(struct irq_domain * d, unsigned int hw_irq)

Get a pointer to the generic chip of a hw_irq

Parameters

struct irq_domain * d

irq domain pointer

unsigned int hw_irq

Hardware interrupt number

void irq_setup_generic_chip(struct irq_chip_generic * gc, u32 msk, enum irq_gc_flags flags, unsigned int clr, unsigned int set)

Setup a range of interrupts with a generic chip

Parameters

struct irq_chip_generic * gc

Generic irq chip holding all data

u32 msk

Bitmask holding the irqs to initialize relative to gc->irq_base

enum irq_gc_flags flags

Flags for initialization

unsigned int clr

IRQ_* bits to clear

unsigned int set

IRQ_* bits to set

Description

Set up max. 32 interrupts starting from gc->irq_base. Note, this initializes all interrupts to the primary irq_chip_type and its associated handler.

int irq_setup_alt_chip(struct irq_data * d, unsigned int type)

Switch to alternative chip

Parameters

struct irq_data * d

irq_data for this interrupt

unsigned int type

Flow type to be initialized

Description

Only to be called from chip->:c:func:irq_set_type() callbacks.

void irq_remove_generic_chip(struct irq_chip_generic * gc, u32 msk, unsigned int clr, unsigned int set)

Remove a chip

Parameters

struct irq_chip_generic * gc

Generic irq chip holding all data

u32 msk

Bitmask holding the irqs to initialize relative to gc->irq_base

unsigned int clr

IRQ_* bits to clear

unsigned int set

IRQ_* bits to set

Description

Remove up to 32 interrupts starting from gc->irq_base.

Structures

This chapter contains the autogenerated documentation of the structures which are used in the generic IRQ layer.

struct irq_common_data

per irq data shared by all irqchips

Definition

struct irq_common_data {
  unsigned int            __private state_use_accessors;
#ifdef CONFIG_NUMA;
  unsigned int            node;
#endif;
  void *handler_data;
  struct msi_desc         *msi_desc;
  cpumask_var_t affinity;
#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK;
  cpumask_var_t effective_affinity;
#endif;
#ifdef CONFIG_GENERIC_IRQ_IPI;
  unsigned int            ipi_offset;
#endif;
};

Members

state_use_accessors

status information for irq chip functions. Use accessor functions to deal with it

node

node index useful for balancing

handler_data

per-IRQ data for the irq_chip methods

msi_desc

MSI descriptor

affinity

IRQ affinity on SMP. If this is an IPI related irq, then this is the mask of the CPUs to which an IPI can be sent.

effective_affinity

The effective IRQ affinity on SMP as some irq chips do not allow multi CPU destinations. A subset of affinity.

ipi_offset

Offset of first IPI target cpu in affinity. Optional.

struct irq_data

per irq chip data passed down to chip functions

Definition

struct irq_data {
  u32 mask;
  unsigned int            irq;
  unsigned long           hwirq;
  struct irq_common_data  *common;
  struct irq_chip         *chip;
  struct irq_domain       *domain;
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY;
  struct irq_data         *parent_data;
#endif;
  void *chip_data;
};

Members

mask

precomputed bitmask for accessing the chip registers

irq

interrupt number

hwirq

hardware interrupt number, local to the interrupt domain

common

point to data shared by all irqchips

chip

low level interrupt hardware access

domain

Interrupt translation domain; responsible for mapping between hwirq number and linux irq number.

parent_data

pointer to parent struct irq_data to support hierarchy irq_domain

chip_data

platform-specific per-chip private data for the chip methods, to allow shared chip implementations

struct irq_chip

hardware interrupt chip descriptor

Definition

struct irq_chip {
  struct device   *parent_device;
  const char      *name;
  unsigned int    (*irq_startup)(struct irq_data *data);
  void (*irq_shutdown)(struct irq_data *data);
  void (*irq_enable)(struct irq_data *data);
  void (*irq_disable)(struct irq_data *data);
  void (*irq_ack)(struct irq_data *data);
  void (*irq_mask)(struct irq_data *data);
  void (*irq_mask_ack)(struct irq_data *data);
  void (*irq_unmask)(struct irq_data *data);
  void (*irq_eoi)(struct irq_data *data);
  int (*irq_set_affinity)(struct irq_data *data, const struct cpumask *dest, bool force);
  int (*irq_retrigger)(struct irq_data *data);
  int (*irq_set_type)(struct irq_data *data, unsigned int flow_type);
  int (*irq_set_wake)(struct irq_data *data, unsigned int on);
  void (*irq_bus_lock)(struct irq_data *data);
  void (*irq_bus_sync_unlock)(struct irq_data *data);
  void (*irq_cpu_online)(struct irq_data *data);
  void (*irq_cpu_offline)(struct irq_data *data);
  void (*irq_suspend)(struct irq_data *data);
  void (*irq_resume)(struct irq_data *data);
  void (*irq_pm_shutdown)(struct irq_data *data);
  void (*irq_calc_mask)(struct irq_data *data);
  void (*irq_print_chip)(struct irq_data *data, struct seq_file *p);
  int (*irq_request_resources)(struct irq_data *data);
  void (*irq_release_resources)(struct irq_data *data);
  void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg);
  void (*irq_write_msi_msg)(struct irq_data *data, struct msi_msg *msg);
  int (*irq_get_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool *state);
  int (*irq_set_irqchip_state)(struct irq_data *data, enum irqchip_irq_state which, bool state);
  int (*irq_set_vcpu_affinity)(struct irq_data *data, void *vcpu_info);
  void (*ipi_send_single)(struct irq_data *data, unsigned int cpu);
  void (*ipi_send_mask)(struct irq_data *data, const struct cpumask *dest);
  int (*irq_nmi_setup)(struct irq_data *data);
  void (*irq_nmi_teardown)(struct irq_data *data);
  unsigned long   flags;
};

Members

parent_device

pointer to parent device for irqchip

name

name for /proc/interrupts

irq_startup

start up the interrupt (defaults to ->enable if NULL)

irq_shutdown

shut down the interrupt (defaults to ->disable if NULL)

irq_enable

enable the interrupt (defaults to chip->unmask if NULL)

irq_disable

disable the interrupt

irq_ack

start of a new interrupt

irq_mask

mask an interrupt source

irq_mask_ack

ack and mask an interrupt source

irq_unmask

unmask an interrupt source

irq_eoi

end of interrupt

irq_set_affinity

Set the CPU affinity on SMP machines. If the force argument is true, it tells the driver to unconditionally apply the affinity setting. Sanity checks against the supplied affinity mask are not required. This is used for CPU hotplug where the target CPU is not yet set in the cpu_online_mask.

irq_retrigger

resend an IRQ to the CPU

irq_set_type

set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ

irq_set_wake

enable/disable power-management wake-on of an IRQ

irq_bus_lock

function to lock access to slow bus (i2c) chips

irq_bus_sync_unlock

function to sync and unlock slow bus (i2c) chips

irq_cpu_online

configure an interrupt source for a secondary CPU

irq_cpu_offline

un-configure an interrupt source for a secondary CPU

irq_suspend

function called from core code on suspend once per chip, when one or more interrupts are installed

irq_resume

function called from core code on resume once per chip, when one ore more interrupts are installed

irq_pm_shutdown

function called from core code on shutdown once per chip

irq_calc_mask

Optional function to set irq_data.mask for special cases

irq_print_chip

optional to print special chip info in show_interrupts

irq_request_resources

optional to request resources before calling any other callback related to this irq

irq_release_resources

optional to release resources acquired with irq_request_resources

irq_compose_msi_msg

optional to compose message content for MSI

irq_write_msi_msg

optional to write message content for MSI

irq_get_irqchip_state

return the internal state of an interrupt

irq_set_irqchip_state

set the internal state of a interrupt

irq_set_vcpu_affinity

optional to target a vCPU in a virtual machine

ipi_send_single

send a single IPI to destination cpus

ipi_send_mask

send an IPI to destination cpus in cpumask

irq_nmi_setup

function called from core code before enabling an NMI

irq_nmi_teardown

function called from core code after disabling an NMI

flags

chip specific flags

struct irq_chip_regs

register offsets for struct irq_gci

Definition

struct irq_chip_regs {
  unsigned long           enable;
  unsigned long           disable;
  unsigned long           mask;
  unsigned long           ack;
  unsigned long           eoi;
  unsigned long           type;
  unsigned long           polarity;
};

Members

enable

Enable register offset to reg_base

disable

Disable register offset to reg_base

mask

Mask register offset to reg_base

ack

Ack register offset to reg_base

eoi

Eoi register offset to reg_base

type

Type configuration register offset to reg_base

polarity

Polarity configuration register offset to reg_base

struct irq_chip_type

Generic interrupt chip instance for a flow type

Definition

struct irq_chip_type {
  struct irq_chip         chip;
  struct irq_chip_regs    regs;
  irq_flow_handler_t handler;
  u32 type;
  u32 mask_cache_priv;
  u32 *mask_cache;
};

Members

chip

The real interrupt chip which provides the callbacks

regs

Register offsets for this chip

handler

Flow handler associated with this chip

type

Chip can handle these flow types

mask_cache_priv

Cached mask register private to the chip type

mask_cache

Pointer to cached mask register

Description

A irq_generic_chip can have several instances of irq_chip_type when it requires different functions and register offsets for different flow types.

struct irq_chip_generic

Generic irq chip data structure

Definition

struct irq_chip_generic {
  raw_spinlock_t lock;
  void __iomem            *reg_base;
  u32 (*reg_readl)(void __iomem *addr);
  void (*reg_writel)(u32 val, void __iomem *addr);
  void (*suspend)(struct irq_chip_generic *gc);
  void (*resume)(struct irq_chip_generic *gc);
  unsigned int            irq_base;
  unsigned int            irq_cnt;
  u32 mask_cache;
  u32 type_cache;
  u32 polarity_cache;
  u32 wake_enabled;
  u32 wake_active;
  unsigned int            num_ct;
  void *private;
  unsigned long           installed;
  unsigned long           unused;
  struct irq_domain       *domain;
  struct list_head        list;
  struct irq_chip_type    chip_types[0];
};

Members

lock

Lock to protect register and cache data access

reg_base

Register base address (virtual)

reg_readl

Alternate I/O accessor (defaults to readl if NULL)

reg_writel

Alternate I/O accessor (defaults to writel if NULL)

suspend

Function called from core code on suspend once per chip; can be useful instead of irq_chip::suspend to handle chip details even when no interrupts are in use

resume

Function called from core code on resume once per chip; can be useful instead of irq_chip::suspend to handle chip details even when no interrupts are in use

irq_base

Interrupt base nr for this chip

irq_cnt

Number of interrupts handled by this chip

mask_cache

Cached mask register shared between all chip types

type_cache

Cached type register

polarity_cache

Cached polarity register

wake_enabled

Interrupt can wakeup from suspend

wake_active

Interrupt is marked as an wakeup from suspend source

num_ct

Number of available irq_chip_type instances (usually 1)

private

Private data for non generic chip callbacks

installed

bitfield to denote installed interrupts

unused

bitfield to denote unused interrupts

domain

irq domain pointer

list

List head for keeping track of instances

chip_types

Array of interrupt irq_chip_types

Description

Note, that irq_chip_generic can have multiple irq_chip_type implementations which can be associated to a particular irq line of an irq_chip_generic instance. That allows to share and protect state in an irq_chip_generic instance when we need to implement different flow mechanisms (level/edge) for it.

enum irq_gc_flags

Initialization flags for generic irq chips

Constants

IRQ_GC_INIT_MASK_CACHE

Initialize the mask_cache by reading mask reg

IRQ_GC_INIT_NESTED_LOCK

Set the lock class of the irqs to nested for irq chips which need to call irq_set_wake() on the parent irq. Usually GPIO implementations

IRQ_GC_MASK_CACHE_PER_TYPE

Mask cache is chip type private

IRQ_GC_NO_MASK

Do not calculate irq_data->mask

IRQ_GC_BE_IO

Use big-endian register accesses (default: LE)

struct irqaction

per interrupt action descriptor

Definition

struct irqaction {
  irq_handler_t handler;
  void *dev_id;
  void __percpu           *percpu_dev_id;
  struct irqaction        *next;
  irq_handler_t thread_fn;
  struct task_struct      *thread;
  struct irqaction        *secondary;
  unsigned int            irq;
  unsigned int            flags;
  unsigned long           thread_flags;
  unsigned long           thread_mask;
  const char              *name;
  struct proc_dir_entry   *dir;
};

Members

handler

interrupt handler function

dev_id

cookie to identify the device

percpu_dev_id

cookie to identify the device

next

pointer to the next irqaction for shared interrupts

thread_fn

interrupt handler function for threaded interrupts

thread

thread pointer for threaded interrupts

secondary

pointer to secondary irqaction (force threading)

irq

interrupt number

flags

flags (see IRQF_* above)

thread_flags

flags related to thread

thread_mask

bitmask for keeping track of thread activity

name

name of the device

dir

pointer to the proc/irq/NN/name entry

struct irq_affinity_notify

context for notification of IRQ affinity changes

Definition

struct irq_affinity_notify {
  unsigned int irq;
  struct kref kref;
  struct work_struct work;
  void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
  void (*release)(struct kref *ref);
};

Members

irq

Interrupt to which notification applies

kref

Reference count, for internal use

work

Work item, for internal use

notify

Function to be called on change. This will be called in process context.

release

Function to be called on release. This will be called in process context. Once registered, the structure must only be freed when this function is called or later.

struct irq_affinity

Description for automatic irq affinity assignements

Definition

struct irq_affinity {
  unsigned int    pre_vectors;
  unsigned int    post_vectors;
  unsigned int    nr_sets;
  unsigned int    set_size[IRQ_AFFINITY_MAX_SETS];
  void (*calc_sets)(struct irq_affinity *, unsigned int nvecs);
  void *priv;
};

Members

pre_vectors

Don't apply affinity to pre_vectors at beginning of the MSI(-X) vector space

post_vectors

Don't apply affinity to post_vectors at end of the MSI(-X) vector space

nr_sets

The number of interrupt sets for which affinity spreading is required

set_size

Array holding the size of each interrupt set

calc_sets

Callback for calculating the number and size of interrupt sets

priv

Private data for usage by calc_sets, usually a pointer to driver/device specific data.

struct irq_affinity_desc

Interrupt affinity descriptor

Definition

struct irq_affinity_desc {
  struct cpumask  mask;
  unsigned int    is_managed : 1;
};

Members

mask

cpumask to hold the affinity assignment

is_managed

1 if the interrupt is managed internally

int irq_set_affinity(unsigned int irq, const struct cpumask * cpumask)

Set the irq affinity of a given irq

Parameters

unsigned int irq

Interrupt to set affinity

const struct cpumask * cpumask

cpumask

Description

Fails if cpumask does not contain an online CPU

int irq_force_affinity(unsigned int irq, const struct cpumask * cpumask)

Force the irq affinity of a given irq

Parameters

unsigned int irq

Interrupt to set affinity

const struct cpumask * cpumask

cpumask

Description

Same as irq_set_affinity, but without checking the mask against online cpus.

Solely for low level cpu hotplug code, where we need to make per cpu interrupts affine before the cpu becomes online.

Public Functions Provided

This chapter contains the autogenerated documentation of the kernel API functions which are exported.

bool synchronize_hardirq(unsigned int irq)

wait for pending hard IRQ handlers (on other CPUs)

Parameters

unsigned int irq

interrupt number to wait for

Description

This function waits for any pending hard 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. It does not take associated threaded handlers into account.

Do not use this for shutdown scenarios where you must be sure that all parts (hardirq and threaded handler) have completed.

Return

false if a threaded handler is active.

This function may be called - with care - from IRQ context.

void synchronize_irq(unsigned int irq)

wait for pending IRQ handlers (on other CPUs)

Parameters

unsigned int irq

interrupt number to wait for

Description

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.

This function may be called - with care - from IRQ context.

int irq_can_set_affinity(unsigned int irq)

Check if the affinity of a given irq can be set

Parameters

unsigned int irq

Interrupt to check

bool irq_can_set_affinity_usr(unsigned int irq)

Check if affinity of a irq can be set from user space

Parameters

unsigned int irq

Interrupt to check

Description

Like irq_can_set_affinity() above, but additionally checks for the AFFINITY_MANAGED flag.

void irq_set_thread_affinity(struct irq_desc * desc)

Notify irq threads to adjust affinity

Parameters

struct irq_desc * desc

irq descriptor which has affitnity changed

Description

We just set IRQTF_AFFINITY and delegate the affinity setting to the interrupt thread itself. We can not call set_cpus_allowed_ptr() here as we hold desc->lock and this code can be called from hard interrupt context.

int irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify * notify)

control notification of IRQ affinity changes

Parameters

unsigned int irq

Interrupt for which to enable/disable notification

struct irq_affinity_notify * notify

Context for notification, or NULL to disable notification. Function pointers must be initialised; the other fields will be initialised by this function.

Description

Must be called in process context. Notification may only be enabled after the IRQ is allocated and must be disabled before the IRQ is freed using free_irq().

int irq_set_vcpu_affinity(unsigned int irq, void * vcpu_info)

Set vcpu affinity for the interrupt

Parameters

unsigned int irq

interrupt number to set affinity

void * vcpu_info

vCPU specific data or pointer to a percpu array of vCPU specific data for percpu_devid interrupts

Description

This function uses the vCPU specific data to set the vCPU affinity for an irq. The vCPU specific data is passed from outside, such as KVM. One example code path is as below: KVM -> IOMMU -> irq_set_vcpu_affinity().

void disable_irq_nosync(unsigned int irq)

disable an irq without waiting

Parameters

unsigned int irq

Interrupt to disable

Description

Disable the selected interrupt line. Disables and Enables are nested. Unlike disable_irq(), this function does not ensure existing instances of the IRQ handler have completed before returning.

This function may be called from IRQ context.

void disable_irq(unsigned int irq)

disable an irq and wait for completion

Parameters

unsigned int irq

Interrupt to disable

Description

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.

This function may be called - with care - from IRQ context.

bool disable_hardirq(unsigned int irq)

disables an irq and waits for hardirq completion

Parameters

unsigned int irq

Interrupt to disable

Description

Disable the selected interrupt line. Enables and Disables are nested. This function waits for any pending hard IRQ handlers for this interrupt to complete before returning. If you use this function while holding a resource the hard IRQ handler may need you will deadlock.

When used to optimistically disable an interrupt from atomic context the return value must be checked.

Return

false if a threaded handler is active.

This function may be called - with care - from IRQ context.

void disable_nmi_nosync(unsigned int irq)

disable an nmi without waiting

Parameters

unsigned int irq

Interrupt to disable

Description

Disable the selected interrupt line. Disables and enables are nested. The interrupt to disable must have been requested through request_nmi. Unlike disable_nmi(), this function does not ensure existing instances of the IRQ handler have completed before returning.

void enable_irq(unsigned int irq)

enable handling of an irq

Parameters

unsigned int irq

Interrupt to enable

Description

Undoes the effect of one call to disable_irq(). If this matches the last disable, processing of interrupts on this IRQ line is re-enabled.

This function may be called from IRQ context only when desc->irq_data.chip->bus_lock and desc->chip->bus_sync_unlock are NULL !

void enable_nmi(unsigned int irq)

enable handling of an nmi

Parameters

unsigned int irq

Interrupt to enable

Description

The interrupt to enable must have been requested through request_nmi. Undoes the effect of one call to disable_nmi(). If this matches the last disable, processing of interrupts on this IRQ line is re-enabled.

int irq_set_irq_wake(unsigned int irq, unsigned int on)

control irq power management wakeup

Parameters

unsigned int irq

interrupt to control

unsigned int on

enable/disable power management wakeup

Description

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.

Wakeup mode lets this IRQ wake the system from sleep states like "suspend to RAM".

void irq_wake_thread(unsigned int irq, void * dev_id)

wake the irq thread for the action identified by dev_id

Parameters

unsigned int irq

Interrupt line

void * dev_id

Device identity for which the thread should be woken

int setup_irq(unsigned int irq, struct irqaction * act)

setup an interrupt

Parameters

unsigned int irq

Interrupt line to setup

struct irqaction * act

irqaction for the interrupt

Description

Used to statically setup interrupts in the early boot process.

void remove_irq(unsigned int irq, struct irqaction * act)

free an interrupt

Parameters

unsigned int irq

Interrupt line to free

struct irqaction * act

irqaction for the interrupt

Description

Used to remove interrupts statically setup by the early boot process.

const void * free_irq(unsigned int irq, void * dev_id)

free an interrupt allocated with request_irq

Parameters

unsigned int irq

Interrupt line to free

void * dev_id

Device identity to free

Description

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.

This function must not be called from interrupt context.

Returns the devname argument passed to request_irq.

int request_threaded_irq(unsigned int irq, irq_handler_t handler, irq_handler_t thread_fn, unsigned long irqflags, const char * devname, void * dev_id)

allocate an interrupt line

Parameters

unsigned int irq

Interrupt line to allocate

irq_handler_t handler

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

irq_handler_t thread_fn

Function called from the irq handler thread If NULL, no irq thread is created

unsigned long irqflags

Interrupt type flags

const char * devname

An ascii name for the claiming device

void * dev_id

A cookie passed back to the handler function

Description

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.

If you want to set up a threaded irq handler for your device then you need to supply handler and thread_fn. handler is 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 thread_fn. This split handler design is necessary to support shared interrupts.

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.

If your interrupt is shared you must pass a non NULL dev_id as this is required when freeing the interrupt.

Flags:

IRQF_SHARED Interrupt is shared IRQF_TRIGGER_* Specify active edge(s) or level

int request_any_context_irq(unsigned int irq, irq_handler_t handler, unsigned long flags, const char * name, void * dev_id)

allocate an interrupt line

Parameters

unsigned int irq

Interrupt line to allocate

irq_handler_t handler

Function to be called when the IRQ occurs. Threaded handler for threaded interrupts.

unsigned long flags

Interrupt type flags

const char * name

An ascii name for the claiming device

void * dev_id

A cookie passed back to the handler function

Description

This call allocates interrupt resources and enables the interrupt line and IRQ handling. It selects either a hardirq or threaded handling method depending on the context.

On failure, it returns a negative value. On success, it returns either IRQC_IS_HARDIRQ or IRQC_IS_NESTED.

int request_nmi(unsigned int irq, irq_handler_t handler, unsigned long irqflags, const char * name, void * dev_id)

allocate an interrupt line for NMI delivery

Parameters

unsigned int irq

Interrupt line to allocate

irq_handler_t handler

Function to be called when the IRQ occurs. Threaded handler for threaded interrupts.

unsigned long irqflags

Interrupt type flags

const char * name

An ascii name for the claiming device

void * dev_id

A cookie passed back to the handler function

Description

This call allocates interrupt resources and enables the interrupt line and IRQ handling. It sets up the IRQ line to be handled as an NMI.

An interrupt line delivering NMIs cannot be shared and IRQ handling cannot be threaded.

Interrupt lines requested for NMI delivering must produce per cpu interrupts and have auto enabling setting disabled.

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.

If the interrupt line cannot be used to deliver NMIs, function will fail and return a negative value.

bool irq_percpu_is_enabled(unsigned int irq)

Check whether the per cpu irq is enabled

Parameters

unsigned int irq

Linux irq number to check for

Description

Must be called from a non migratable context. Returns the enable state of a per cpu interrupt on the current cpu.

void remove_percpu_irq(unsigned int irq, struct irqaction * act)

free a per-cpu interrupt

Parameters

unsigned int irq

Interrupt line to free

struct irqaction * act

irqaction for the interrupt

Description

Used to remove interrupts statically setup by the early boot process.

void free_percpu_irq(unsigned int irq, void __percpu * dev_id)

free an interrupt allocated with request_percpu_irq

Parameters

unsigned int irq

Interrupt line to free

void __percpu * dev_id

Device identity to free

Description

Remove a percpu interrupt handler. The handler is removed, but the interrupt line is not disabled. This must be done on each CPU before calling this function. The function does not return until any executing interrupts for this IRQ have completed.

This function must not be called from interrupt context.

int setup_percpu_irq(unsigned int irq, struct irqaction * act)

setup a per-cpu interrupt

Parameters

unsigned int irq

Interrupt line to setup

struct irqaction * act

irqaction for the interrupt

Description

Used to statically setup per-cpu interrupts in the early boot process.

int __request_percpu_irq(unsigned int irq, irq_handler_t handler, unsigned long flags, const char * devname, void __percpu * dev_id)

allocate a percpu interrupt line

Parameters

unsigned int irq

Interrupt line to allocate

irq_handler_t handler

Function to be called when the IRQ occurs.

unsigned long flags

Interrupt type flags (IRQF_TIMER only)

const char * devname

An ascii name for the claiming device

void __percpu * dev_id

A percpu cookie passed back to the handler function

Description

This call allocates interrupt resources and enables the interrupt on the local CPU. If the interrupt is supposed to be enabled on other CPUs, it has to be done on each CPU using enable_percpu_irq().

Dev_id must be globally unique. It is a per-cpu variable, and the handler gets called with the interrupted CPU's instance of that variable.

int request_percpu_nmi(unsigned int irq, irq_handler_t handler, const char * name, void __percpu * dev_id)

allocate a percpu interrupt line for NMI delivery

Parameters

unsigned int irq

Interrupt line to allocate

irq_handler_t handler

Function to be called when the IRQ occurs.

const char * name

An ascii name for the claiming device

void __percpu * dev_id

A percpu cookie passed back to the handler function

Description

This call allocates interrupt resources for a per CPU NMI. Per CPU NMIs have to be setup on each CPU by calling prepare_percpu_nmi() before being enabled on the same CPU by using enable_percpu_nmi().

Dev_id must be globally unique. It is a per-cpu variable, and the handler gets called with the interrupted CPU's instance of that variable.

Interrupt lines requested for NMI delivering should have auto enabling setting disabled.

If the interrupt line cannot be used to deliver NMIs, function will fail returning a negative value.

int prepare_percpu_nmi(unsigned int irq)

performs CPU local setup for NMI delivery

Parameters

unsigned int irq

Interrupt line to prepare for NMI delivery

Description

This call prepares an interrupt line to deliver NMI on the current CPU, before that interrupt line gets enabled with enable_percpu_nmi().

As a CPU local operation, this should be called from non-preemptible context.

If the interrupt line cannot be used to deliver NMIs, function will fail returning a negative value.

void teardown_percpu_nmi(unsigned int irq)

undoes NMI setup of IRQ line

Parameters

unsigned int irq

Interrupt line from which CPU local NMI configuration should be removed

Description

This call undoes the setup done by prepare_percpu_nmi().

IRQ line should not be enabled for the current CPU.

As a CPU local operation, this should be called from non-preemptible context.

int irq_get_irqchip_state(unsigned int irq, enum irqchip_irq_state which, bool * state)

returns the irqchip state of a interrupt.

Parameters

unsigned int irq

Interrupt line that is forwarded to a VM

enum irqchip_irq_state which

One of IRQCHIP_STATE_* the caller wants to know about

bool * state

a pointer to a boolean where the state is to be storeed

Description

This call snapshots the internal irqchip state of an interrupt, returning into state the bit corresponding to stage which

This function should be called with preemption disabled if the interrupt controller has per-cpu registers.

int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which, bool val)

set the state of a forwarded interrupt.

Parameters

unsigned int irq

Interrupt line that is forwarded to a VM

enum irqchip_irq_state which

State to be restored (one of IRQCHIP_STATE_*)

bool val

Value corresponding to which

Description

This call sets the internal irqchip state of an interrupt, depending on the value of which.

This function should be called with preemption disabled if the interrupt controller has per-cpu registers.

int irq_set_chip(unsigned int irq, struct irq_chip * chip)

set the irq chip for an irq

Parameters

unsigned int irq

irq number

struct irq_chip * chip

pointer to irq chip description structure

int irq_set_irq_type(unsigned int irq, unsigned int type)

set the irq trigger type for an irq

Parameters

unsigned int irq

irq number

unsigned int type

IRQ_TYPE_{LEVEL,EDGE}_* value - see include/linux/irq.h

int irq_set_handler_data(unsigned int irq, void * data)

set irq handler data for an irq

Parameters

unsigned int irq

Interrupt number

void * data

Pointer to interrupt specific data

Description

Set the hardware irq controller data for an irq

int irq_set_msi_desc_off(unsigned int irq_base, unsigned int irq_offset, struct msi_desc * entry)

set MSI descriptor data for an irq at offset

Parameters

unsigned int irq_base

Interrupt number base

unsigned int irq_offset

Interrupt number offset

struct msi_desc * entry

Pointer to MSI descriptor data

Description

Set the MSI descriptor entry for an irq at offset

int irq_set_msi_desc(unsigned int irq, struct msi_desc * entry)

set MSI descriptor data for an irq

Parameters

unsigned int irq

Interrupt number

struct msi_desc * entry

Pointer to MSI descriptor data

Description

Set the MSI descriptor entry for an irq

int irq_set_chip_data(unsigned int irq, void * data)

set irq chip data for an irq

Parameters

unsigned int irq

Interrupt number

void * data

Pointer to chip specific data

Description

Set the hardware irq chip data for an irq

void irq_disable(struct irq_desc * desc)

Mark interrupt disabled

Parameters

struct irq_desc * desc

irq descriptor which should be disabled

Description

If the chip does not implement the irq_disable callback, we use a lazy disable approach. That means we mark the interrupt disabled, but leave the hardware unmasked. That's an optimization because we avoid the hardware access for the common case where no interrupt happens after we marked it disabled. If an interrupt happens, then the interrupt flow handler masks the line at the hardware level and marks it pending.

If the interrupt chip does not implement the irq_disable callback, a driver can disable the lazy approach for a particular irq line by calling 'irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY)'. This can be used for devices which cannot disable the interrupt at the device level under certain circumstances and have to use disable_irq[_nosync] instead.

void handle_simple_irq(struct irq_desc * desc)

Simple and software-decoded IRQs.

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Simple interrupts are either sent from a demultiplexing interrupt handler or come from hardware, where no interrupt hardware control is necessary.

Note

The caller is expected to handle the ack, clear, mask and

unmask issues if necessary.

void handle_untracked_irq(struct irq_desc * desc)

Simple and software-decoded IRQs.

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Untracked interrupts are sent from a demultiplexing interrupt handler when the demultiplexer does not know which device it its multiplexed irq domain generated the interrupt. IRQ's handled through here are not subjected to stats tracking, randomness, or spurious interrupt detection.

Note

Like handle_simple_irq, the caller is expected to handle

the ack, clear, mask and unmask issues if necessary.

void handle_level_irq(struct irq_desc * desc)

Level type irq handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

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.

void handle_fasteoi_irq(struct irq_desc * desc)

irq handler for transparent controllers

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Only a single callback will be issued to the chip: an ->:c:func:eoi() call when the interrupt has been serviced. This enables support for modern forms of interrupt handlers, which handle the flow details in hardware, transparently.

void handle_fasteoi_nmi(struct irq_desc * desc)

irq handler for NMI interrupt lines

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

A simple NMI-safe handler, considering the restrictions from request_nmi.

Only a single callback will be issued to the chip: an ->:c:func:eoi() call when the interrupt has been serviced. This enables support for modern forms of interrupt handlers, which handle the flow details in hardware, transparently.

void handle_edge_irq(struct irq_desc * desc)

edge type IRQ handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Interrupt occures on the falling and/or rising edge of a hardware signal. The occurrence 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 associated 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.

void handle_edge_eoi_irq(struct irq_desc * desc)

edge eoi type IRQ handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Similar as the above handle_edge_irq, but using eoi and w/o the mask/unmask logic.

void handle_percpu_irq(struct irq_desc * desc)

Per CPU local irq handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Per CPU interrupts on SMP machines without locking requirements

void handle_percpu_devid_irq(struct irq_desc * desc)

Per CPU local irq handler with per cpu dev ids

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Per CPU interrupts on SMP machines without locking requirements. Same as handle_percpu_irq() above but with the following extras:

action->percpu_dev_id is a pointer to percpu variables which contain the real device id for the cpu on which this handler is called

void handle_percpu_devid_fasteoi_nmi(struct irq_desc * desc)

Per CPU local NMI handler with per cpu dev ids

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Similar to handle_fasteoi_nmi, but handling the dev_id cookie as a percpu pointer.

void irq_cpu_online(void)

Invoke all irq_cpu_online functions.

Parameters

void

no arguments

Description

Iterate through all irqs and invoke the chip.:c:func:irq_cpu_online() for each.

void irq_cpu_offline(void)

Invoke all irq_cpu_offline functions.

Parameters

void

no arguments

Description

Iterate through all irqs and invoke the chip.:c:func:irq_cpu_offline() for each.

void handle_fasteoi_ack_irq(struct irq_desc * desc)

irq handler for edge hierarchy stacked on transparent controllers

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Like handle_fasteoi_irq(), but for use with hierarchy where the irq_chip also needs to have its ->:c:func:irq_ack() function called.

void handle_fasteoi_mask_irq(struct irq_desc * desc)

irq handler for level hierarchy stacked on transparent controllers

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Like handle_fasteoi_irq(), but for use with hierarchy where the irq_chip also needs to have its ->:c:func:irq_mask_ack() function called.

void irq_chip_enable_parent(struct irq_data * data)

Enable the parent interrupt (defaults to unmask if NULL)

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_disable_parent(struct irq_data * data)

Disable the parent interrupt (defaults to mask if NULL)

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_ack_parent(struct irq_data * data)

Acknowledge the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_mask_parent(struct irq_data * data)

Mask the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_mask_ack_parent(struct irq_data * data)

Mask and acknowledge the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_unmask_parent(struct irq_data * data)

Unmask the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_eoi_parent(struct irq_data * data)

Invoke EOI on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

int irq_chip_set_affinity_parent(struct irq_data * data, const struct cpumask * dest, bool force)

Set affinity on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

const struct cpumask * dest

The affinity mask to set

bool force

Flag to enforce setting (disable online checks)

Description

Conditinal, as the underlying parent chip might not implement it.

int irq_chip_set_type_parent(struct irq_data * data, unsigned int type)

Set IRQ type on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

unsigned int type

IRQ_TYPE_{LEVEL,EDGE}_* value - see include/linux/irq.h

Description

Conditional, as the underlying parent chip might not implement it.

int irq_chip_retrigger_hierarchy(struct irq_data * data)

Retrigger an interrupt in hardware

Parameters

struct irq_data * data

Pointer to interrupt specific data

Description

Iterate through the domain hierarchy of the interrupt and check whether a hw retrigger function exists. If yes, invoke it.

int irq_chip_set_vcpu_affinity_parent(struct irq_data * data, void * vcpu_info)

Set vcpu affinity on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void * vcpu_info

The vcpu affinity information

int irq_chip_set_wake_parent(struct irq_data * data, unsigned int on)

Set/reset wake-up on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

unsigned int on

Whether to set or reset the wake-up capability of this irq

Description

Conditional, as the underlying parent chip might not implement it.

int irq_chip_request_resources_parent(struct irq_data * data)

Request resources on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_release_resources_parent(struct irq_data * data)

Release resources on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

int irq_chip_compose_msi_msg(struct irq_data * data, struct msi_msg * msg)

Componse msi message for a irq chip

Parameters

struct irq_data * data

Pointer to interrupt specific data

struct msi_msg * msg

Pointer to the MSI message

Description

For hierarchical domains we find the first chip in the hierarchy which implements the irq_compose_msi_msg callback. For non hierarchical we use the top level chip.

int irq_chip_pm_get(struct irq_data * data)

Enable power for an IRQ chip

Parameters

struct irq_data * data

Pointer to interrupt specific data

Description

Enable the power to the IRQ chip referenced by the interrupt data structure.

int irq_chip_pm_put(struct irq_data * data)

Disable power for an IRQ chip

Parameters

struct irq_data * data

Pointer to interrupt specific data

Description

Disable the power to the IRQ chip referenced by the interrupt data structure, belongs. Note that power will only be disabled, once this function has been called for all IRQs that have called irq_chip_pm_get().

Internal Functions Provided

This chapter contains the autogenerated documentation of the internal functions.

int generic_handle_irq(unsigned int irq)

Invoke the handler for a particular irq

Parameters

unsigned int irq

The irq number to handle

int __handle_domain_irq(struct irq_domain * domain, unsigned int hwirq, bool lookup, struct pt_regs * regs)

Invoke the handler for a HW irq belonging to a domain

Parameters

struct irq_domain * domain

The domain where to perform the lookup

unsigned int hwirq

The HW irq number to convert to a logical one

bool lookup

Whether to perform the domain lookup or not

struct pt_regs * regs

Register file coming from the low-level handling code

Return

0 on success, or -EINVAL if conversion has failed

int handle_domain_nmi(struct irq_domain * domain, unsigned int hwirq, struct pt_regs * regs)

Invoke the handler for a HW irq belonging to a domain

Parameters

struct irq_domain * domain

The domain where to perform the lookup

unsigned int hwirq

The HW irq number to convert to a logical one

struct pt_regs * regs

Register file coming from the low-level handling code

Return

0 on success, or -EINVAL if conversion has failed

void irq_free_descs(unsigned int from, unsigned int cnt)

free irq descriptors

Parameters

unsigned int from

Start of descriptor range

unsigned int cnt

Number of consecutive irqs to free

int __ref __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node, struct module * owner, const struct irq_affinity_desc * affinity)

allocate and initialize a range of irq descriptors

Parameters

int irq

Allocate for specific irq number if irq >= 0

unsigned int from

Start the search from this irq number

unsigned int cnt

Number of consecutive irqs to allocate.

int node

Preferred node on which the irq descriptor should be allocated

struct module * owner

Owning module (can be NULL)

const struct irq_affinity_desc * affinity

Optional pointer to an affinity mask array of size cnt which hints where the irq descriptors should be allocated and which default affinities to use

Description

Returns the first irq number or error code

unsigned int irq_alloc_hwirqs(int cnt, int node)

Allocate an irq descriptor and initialize the hardware

Parameters

int cnt

number of interrupts to allocate

int node

node on which to allocate

Description

Returns an interrupt number > 0 or 0, if the allocation fails.

void irq_free_hwirqs(unsigned int from, int cnt)

Free irq descriptor and cleanup the hardware

Parameters

unsigned int from

Free from irq number

int cnt

number of interrupts to free

unsigned int irq_get_next_irq(unsigned int offset)

get next allocated irq number

Parameters

unsigned int offset

where to start the search

Description

Returns next irq number after offset or nr_irqs if none is found.

unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)

Get the statistics for an interrupt on a cpu

Parameters

unsigned int irq

The interrupt number

int cpu

The cpu number

Description

Returns the sum of interrupt counts on cpu since boot for irq. The caller must ensure that the interrupt is not removed concurrently.

unsigned int kstat_irqs(unsigned int irq)

Get the statistics for an interrupt

Parameters

unsigned int irq

The interrupt number

Description

Returns the sum of interrupt counts on all cpus since boot for irq. The caller must ensure that the interrupt is not removed concurrently.

unsigned int kstat_irqs_usr(unsigned int irq)

Get the statistics for an interrupt

Parameters

unsigned int irq

The interrupt number

Description

Returns the sum of interrupt counts on all cpus since boot for irq. Contrary to kstat_irqs() this can be called from any context. It uses rcu since a concurrent removal of an interrupt descriptor is observing an rcu grace period before delayed_free_desc()/irq_kobj_release().

void handle_bad_irq(struct irq_desc * desc)

handle spurious and unhandled irqs

Parameters

struct irq_desc * desc

description of the interrupt

Description

Handles spurious and unhandled IRQ's. It also prints a debugmessage.

int irq_set_chip(unsigned int irq, struct irq_chip * chip)

set the irq chip for an irq

Parameters

unsigned int irq

irq number

struct irq_chip * chip

pointer to irq chip description structure

int irq_set_irq_type(unsigned int irq, unsigned int type)

set the irq trigger type for an irq

Parameters

unsigned int irq

irq number

unsigned int type

IRQ_TYPE_{LEVEL,EDGE}_* value - see include/linux/irq.h

int irq_set_handler_data(unsigned int irq, void * data)

set irq handler data for an irq

Parameters

unsigned int irq

Interrupt number

void * data

Pointer to interrupt specific data

Description

Set the hardware irq controller data for an irq

int irq_set_msi_desc_off(unsigned int irq_base, unsigned int irq_offset, struct msi_desc * entry)

set MSI descriptor data for an irq at offset

Parameters

unsigned int irq_base

Interrupt number base

unsigned int irq_offset

Interrupt number offset

struct msi_desc * entry

Pointer to MSI descriptor data

Description

Set the MSI descriptor entry for an irq at offset

int irq_set_msi_desc(unsigned int irq, struct msi_desc * entry)

set MSI descriptor data for an irq

Parameters

unsigned int irq

Interrupt number

struct msi_desc * entry

Pointer to MSI descriptor data

Description

Set the MSI descriptor entry for an irq

int irq_set_chip_data(unsigned int irq, void * data)

set irq chip data for an irq

Parameters

unsigned int irq

Interrupt number

void * data

Pointer to chip specific data

Description

Set the hardware irq chip data for an irq

void irq_disable(struct irq_desc * desc)

Mark interrupt disabled

Parameters

struct irq_desc * desc

irq descriptor which should be disabled

Description

If the chip does not implement the irq_disable callback, we use a lazy disable approach. That means we mark the interrupt disabled, but leave the hardware unmasked. That's an optimization because we avoid the hardware access for the common case where no interrupt happens after we marked it disabled. If an interrupt happens, then the interrupt flow handler masks the line at the hardware level and marks it pending.

If the interrupt chip does not implement the irq_disable callback, a driver can disable the lazy approach for a particular irq line by calling 'irq_set_status_flags(irq, IRQ_DISABLE_UNLAZY)'. This can be used for devices which cannot disable the interrupt at the device level under certain circumstances and have to use disable_irq[_nosync] instead.

void handle_simple_irq(struct irq_desc * desc)

Simple and software-decoded IRQs.

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Simple interrupts are either sent from a demultiplexing interrupt handler or come from hardware, where no interrupt hardware control is necessary.

Note

The caller is expected to handle the ack, clear, mask and

unmask issues if necessary.

void handle_untracked_irq(struct irq_desc * desc)

Simple and software-decoded IRQs.

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Untracked interrupts are sent from a demultiplexing interrupt handler when the demultiplexer does not know which device it its multiplexed irq domain generated the interrupt. IRQ's handled through here are not subjected to stats tracking, randomness, or spurious interrupt detection.

Note

Like handle_simple_irq, the caller is expected to handle

the ack, clear, mask and unmask issues if necessary.

void handle_level_irq(struct irq_desc * desc)

Level type irq handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

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.

void handle_fasteoi_irq(struct irq_desc * desc)

irq handler for transparent controllers

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Only a single callback will be issued to the chip: an ->:c:func:eoi() call when the interrupt has been serviced. This enables support for modern forms of interrupt handlers, which handle the flow details in hardware, transparently.

void handle_fasteoi_nmi(struct irq_desc * desc)

irq handler for NMI interrupt lines

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

A simple NMI-safe handler, considering the restrictions from request_nmi.

Only a single callback will be issued to the chip: an ->:c:func:eoi() call when the interrupt has been serviced. This enables support for modern forms of interrupt handlers, which handle the flow details in hardware, transparently.

void handle_edge_irq(struct irq_desc * desc)

edge type IRQ handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Interrupt occures on the falling and/or rising edge of a hardware signal. The occurrence 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 associated 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.

void handle_edge_eoi_irq(struct irq_desc * desc)

edge eoi type IRQ handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Similar as the above handle_edge_irq, but using eoi and w/o the mask/unmask logic.

void handle_percpu_irq(struct irq_desc * desc)

Per CPU local irq handler

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Per CPU interrupts on SMP machines without locking requirements

void handle_percpu_devid_irq(struct irq_desc * desc)

Per CPU local irq handler with per cpu dev ids

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Per CPU interrupts on SMP machines without locking requirements. Same as handle_percpu_irq() above but with the following extras:

action->percpu_dev_id is a pointer to percpu variables which contain the real device id for the cpu on which this handler is called

void handle_percpu_devid_fasteoi_nmi(struct irq_desc * desc)

Per CPU local NMI handler with per cpu dev ids

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Similar to handle_fasteoi_nmi, but handling the dev_id cookie as a percpu pointer.

void irq_cpu_online(void)

Invoke all irq_cpu_online functions.

Parameters

void

no arguments

Description

Iterate through all irqs and invoke the chip.:c:func:irq_cpu_online() for each.

void irq_cpu_offline(void)

Invoke all irq_cpu_offline functions.

Parameters

void

no arguments

Description

Iterate through all irqs and invoke the chip.:c:func:irq_cpu_offline() for each.

void handle_fasteoi_ack_irq(struct irq_desc * desc)

irq handler for edge hierarchy stacked on transparent controllers

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Like handle_fasteoi_irq(), but for use with hierarchy where the irq_chip also needs to have its ->:c:func:irq_ack() function called.

void handle_fasteoi_mask_irq(struct irq_desc * desc)

irq handler for level hierarchy stacked on transparent controllers

Parameters

struct irq_desc * desc

the interrupt description structure for this irq

Description

Like handle_fasteoi_irq(), but for use with hierarchy where the irq_chip also needs to have its ->:c:func:irq_mask_ack() function called.

void irq_chip_enable_parent(struct irq_data * data)

Enable the parent interrupt (defaults to unmask if NULL)

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_disable_parent(struct irq_data * data)

Disable the parent interrupt (defaults to mask if NULL)

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_ack_parent(struct irq_data * data)

Acknowledge the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_mask_parent(struct irq_data * data)

Mask the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_mask_ack_parent(struct irq_data * data)

Mask and acknowledge the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_unmask_parent(struct irq_data * data)

Unmask the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_eoi_parent(struct irq_data * data)

Invoke EOI on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

int irq_chip_set_affinity_parent(struct irq_data * data, const struct cpumask * dest, bool force)

Set affinity on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

const struct cpumask * dest

The affinity mask to set

bool force

Flag to enforce setting (disable online checks)

Description

Conditinal, as the underlying parent chip might not implement it.

int irq_chip_set_type_parent(struct irq_data * data, unsigned int type)

Set IRQ type on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

unsigned int type

IRQ_TYPE_{LEVEL,EDGE}_* value - see include/linux/irq.h

Description

Conditional, as the underlying parent chip might not implement it.

int irq_chip_retrigger_hierarchy(struct irq_data * data)

Retrigger an interrupt in hardware

Parameters

struct irq_data * data

Pointer to interrupt specific data

Description

Iterate through the domain hierarchy of the interrupt and check whether a hw retrigger function exists. If yes, invoke it.

int irq_chip_set_vcpu_affinity_parent(struct irq_data * data, void * vcpu_info)

Set vcpu affinity on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void * vcpu_info

The vcpu affinity information

int irq_chip_set_wake_parent(struct irq_data * data, unsigned int on)

Set/reset wake-up on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

unsigned int on

Whether to set or reset the wake-up capability of this irq

Description

Conditional, as the underlying parent chip might not implement it.

int irq_chip_request_resources_parent(struct irq_data * data)

Request resources on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

void irq_chip_release_resources_parent(struct irq_data * data)

Release resources on the parent interrupt

Parameters

struct irq_data * data

Pointer to interrupt specific data

int irq_chip_compose_msi_msg(struct irq_data * data, struct msi_msg * msg)

Componse msi message for a irq chip

Parameters

struct irq_data * data

Pointer to interrupt specific data

struct msi_msg * msg

Pointer to the MSI message

Description

For hierarchical domains we find the first chip in the hierarchy which implements the irq_compose_msi_msg callback. For non hierarchical we use the top level chip.

int irq_chip_pm_get(struct irq_data * data)

Enable power for an IRQ chip

Parameters

struct irq_data * data

Pointer to interrupt specific data

Description

Enable the power to the IRQ chip referenced by the interrupt data structure.

int irq_chip_pm_put(struct irq_data * data)

Disable power for an IRQ chip

Parameters

struct irq_data * data

Pointer to interrupt specific data

Description

Disable the power to the IRQ chip referenced by the interrupt data structure, belongs. Note that power will only be disabled, once this function has been called for all IRQs that have called irq_chip_pm_get().

Credits

The following people have contributed to this document:

  1. Thomas Gleixner tglx@linutronix.de

  2. Ingo Molnar mingo@elte.hu