English

Chinese (Simplified)

The irq_domain Interrupt Number Mapping Library¶

The current design of the Linux kernel uses a single large number space where each separate IRQ source is assigned a unique number. This is simple when there is only one interrupt controller. But in systems with multiple interrupt controllers, the kernel must ensure that each one gets assigned non-overlapping allocations of Linux IRQ numbers.

The number of interrupt controllers registered as unique irqchips shows a rising tendency. For example, subdrivers of different kinds such as GPIO controllers avoid reimplementing identical callback mechanisms as the IRQ core system by modelling their interrupt handlers as irqchips. I.e. in effect cascading interrupt controllers.

So in the past, IRQ numbers could be chosen so that they match the hardware IRQ line into the root interrupt controller (i.e. the component actually firing the interrupt line to the CPU). Nowadays, this number is just a number and the number loose all kind of correspondence to hardware interrupt numbers.

For this reason, we need a mechanism to separate controller-local interrupt numbers, called hardware IRQs, from Linux IRQ numbers.

The irq_alloc_desc*() and irq_free_desc*() APIs provide allocation of IRQ numbers, but they don’t provide any support for reverse mapping of the controller-local IRQ (hwirq) number into the Linux IRQ number space.

The irq_domain library adds a mapping between hwirq and IRQ numbers on top of the irq_alloc_desc*() API. An irq_domain to manage the mapping is preferred over interrupt controller drivers open coding their own reverse mapping scheme.

irq_domain also implements a translation from an abstract struct irq_fwspec to hwirq numbers (Device Tree, non-DT firmware node, ACPI GSI, and software node so far), and can be easily extended to support other IRQ topology data sources. The implementation is performed without any extra platform support code.

irq_domain Usage¶

struct irq_domain could be defined as an irq domain controller. That is, it handles the mapping between hardware and virtual interrupt numbers for a given interrupt domain. The domain structure is generally created by the PIC code for a given PIC instance (though a domain can cover more than one PIC if they have a flat number model). It is the domain callbacks that are responsible for setting the irq_chip on a given irq_desc after it has been mapped.

The host code and data structures use a fwnode_handle pointer to identify the domain. In some cases, and in order to preserve source code compatibility, this fwnode pointer is “upgraded” to a DT device_node. For those firmware infrastructures that do not provide a unique identifier for an interrupt controller, the irq_domain code offers a fwnode allocator.

An interrupt controller driver creates and registers a struct irq_domain by calling one of the irq_domain_create_*() functions (each mapping method has a different allocator function, more on that later). The function will return a pointer to the struct irq_domain on success. The caller must provide the allocator function with a struct irq_domain_ops pointer.

In most cases, the irq_domain will begin empty without any mappings between hwirq and IRQ numbers. Mappings are added to the irq_domain by calling irq_create_mapping() which accepts the irq_domain and a hwirq number as arguments. If a mapping for the hwirq doesn’t already exist, irq_create_mapping() allocates a new Linux irq_desc, associates it with the hwirq, and calls the irq_domain_ops.map() callback. In there, the driver can perform any required hardware setup.

Once a mapping has been established, it can be retrieved or used via a variety of methods:

irq_resolve_mapping() returns a pointer to the irq_desc structure for a given domain and hwirq number, and NULL if there was no mapping.
irq_find_mapping() returns a Linux IRQ number for a given domain and hwirq number, and 0 if there was no mapping
generic_handle_domain_irq() handles an interrupt described by a domain and a hwirq number

Note that irq domain lookups must happen in contexts that are compatible with a RCU read-side critical section.

The irq_create_mapping() function must be called at least once before any call to irq_find_mapping(), lest the descriptor will not be allocated.

If the driver has the Linux IRQ number or the irq_data pointer, and needs to know the associated hwirq number (such as in the irq_chip callbacks) then it can be directly obtained from irq_data.hwirq.

Types of irq_domain Mappings¶

There are several mechanisms available for reverse mapping from hwirq to Linux irq, and each mechanism uses a different allocation function. Which reverse map type should be used depends on the use case. Each of the reverse map types are described below:

Linear¶

irq_domain_create_linear()

The linear reverse map maintains a fixed size table indexed by the hwirq number. When a hwirq is mapped, an irq_desc is allocated for the hwirq, and the IRQ number is stored in the table.

The Linear map is a good choice when the maximum number of hwirqs is fixed and a relatively small number (~ < 256). The advantages of this map are fixed time lookup for IRQ numbers, and irq_descs are only allocated for in-use IRQs. The disadvantage is that the table must be as large as the largest possible hwirq number.

The majority of drivers should use the Linear map.

Tree¶

irq_domain_create_tree()

The irq_domain maintains a radix tree map from hwirq numbers to Linux IRQs. When an hwirq is mapped, an irq_desc is allocated and the hwirq is used as the lookup key for the radix tree.

The tree map is a good choice if the hwirq number can be very large since it doesn’t need to allocate a table as large as the largest hwirq number. The disadvantage is that hwirq to IRQ number lookup is dependent on how many entries are in the table.

Very few drivers should need this mapping.

No Map¶

irq_domain_create_nomap()

The No Map mapping is to be used when the hwirq number is programmable in the hardware. In this case it is best to program the Linux IRQ number into the hardware itself so that no mapping is required. Calling irq_create_direct_mapping() will allocate a Linux IRQ number and call the .map() callback so that driver can program the Linux IRQ number into the hardware.

Most drivers cannot use this mapping, and it is now gated on the CONFIG_IRQ_DOMAIN_NOMAP option. Please refrain from introducing new users of this API.

Legacy¶

irq_domain_create_simple()
irq_domain_create_legacy()

The Legacy mapping is a special case for drivers that already have a range of irq_descs allocated for the hwirqs. It is used when the driver cannot be immediately converted to use the linear mapping. For example, many embedded system board support files use a set of #defines for IRQ numbers that are passed to struct device registrations. In that case the Linux IRQ numbers cannot be dynamically assigned and the legacy mapping should be used.

As the name implies, the *_legacy() functions are deprecated and only exist to ease the support of ancient platforms. No new users should be added. Same goes for the *_simple() functions when their use results in the legacy behaviour.

The legacy map assumes a contiguous range of IRQ numbers has already been allocated for the controller and that the IRQ number can be calculated by adding a fixed offset to the hwirq number, and visa-versa. The disadvantage is that it requires the interrupt controller to manage IRQ allocations and it requires an irq_desc to be allocated for every hwirq, even if it is unused.

The legacy map should only be used if fixed IRQ mappings must be supported. For example, ISA controllers would use the legacy map for mapping Linux IRQs 0-15 so that existing ISA drivers get the correct IRQ numbers.

Most users of legacy mappings should use irq_domain_create_simple() which will use a legacy domain only if an IRQ range is supplied by the system and will otherwise use a linear domain mapping. The semantics of this call are such that if an IRQ range is specified then descriptors will be allocated on-the-fly for it, and if no range is specified it will fall through to irq_domain_create_linear() which means no irq descriptors will be allocated.

A typical use case for simple domains is where an irqchip provider is supporting both dynamic and static IRQ assignments.

In order to avoid ending up in a situation where a linear domain is used and no descriptor gets allocated it is very important to make sure that the driver using the simple domain call irq_create_mapping() before any irq_find_mapping() since the latter will actually work for the static IRQ assignment case.

Hierarchy IRQ Domain¶

On some architectures, there may be multiple interrupt controllers involved in delivering an interrupt from the device to the target CPU. Let’s look at a typical interrupt delivering path on x86 platforms:

Device --> IOAPIC -> Interrupt remapping Controller -> Local APIC -> CPU

There are three interrupt controllers involved:

IOAPIC controller
Interrupt remapping controller
Local APIC controller

To support such a hardware topology and make software architecture match hardware architecture, an irq_domain data structure is built for each interrupt controller and those irq_domains are organized into hierarchy. When building irq_domain hierarchy, the irq_domain near to the device is child and the irq_domain near to CPU is parent. So a hierarchy structure as below will be built for the example above:

CPU Vector irq_domain (root irq_domain to manage CPU vectors)
        ^
        |
Interrupt Remapping irq_domain (manage irq_remapping entries)
        ^
        |
IOAPIC irq_domain (manage IOAPIC delivery entries/pins)

There are four major interfaces to use hierarchy irq_domain:

irq_domain_alloc_irqs(): allocate IRQ descriptors and interrupt controller related resources to deliver these interrupts.
irq_domain_free_irqs(): free IRQ descriptors and interrupt controller related resources associated with these interrupts.
irq_domain_activate_irq(): activate interrupt controller hardware to deliver the interrupt.
irq_domain_deactivate_irq(): deactivate interrupt controller hardware to stop delivering the interrupt.

The following is needed to support hierarchy irq_domain:

The parent field in struct irq_domain is used to maintain irq_domain hierarchy information.
The parent_data field in struct irq_data is used to build hierarchy irq_data to match hierarchy irq_domains. The irq_data is used to store irq_domain pointer and hardware irq number.
The alloc(), free(), and other callbacks in struct irq_domain_ops to support hierarchy irq_domain operations.

With the support of hierarchy irq_domain and hierarchy irq_data ready, an irq_domain structure is built for each interrupt controller, and an irq_data structure is allocated for each irq_domain associated with an IRQ.

For an interrupt controller driver to support hierarchy irq_domain, it needs to:

Implement irq_domain_ops.alloc() and irq_domain_ops.free()
Optionally, implement irq_domain_ops.activate() and irq_domain_ops.deactivate().
Optionally, implement an irq_chip to manage the interrupt controller hardware.
There is no need to implement irq_domain_ops.map() and irq_domain_ops.unmap(). They are unused with hierarchy irq_domain.

Note the hierarchy irq_domain is in no way x86-specific, and is heavily used to support other architectures, such as ARM, ARM64 etc.

Stacked irq_chip¶

Now, we could go one step further to support stacked (hierarchy) irq_chip. That is, an irq_chip is associated with each irq_data along the hierarchy. A child irq_chip may implement a required action by itself or by cooperating with its parent irq_chip.

With stacked irq_chip, interrupt controller driver only needs to deal with the hardware managed by itself and may ask for services from its parent irq_chip when needed. So we could achieve a much cleaner software architecture.

Debugging¶

Most of the internals of the IRQ subsystem are exposed in debugfs by turning CONFIG_GENERIC_IRQ_DEBUGFS on.

Structures and Public Functions Provided¶

This chapter contains the autogenerated documentation of the structures and exported kernel API functions which are used for IRQ domains.

struct irq_fwspec¶: generic IRQ specifier structure

Definition:

struct irq_fwspec {
    struct fwnode_handle    *fwnode;
    int param_count;
    u32 param[IRQ_DOMAIN_IRQ_SPEC_PARAMS];
};

Members

fwnode: Pointer to a firmware-specific descriptor
param_count: Number of device-specific parameters
param: Device-specific parameters

Description

This structure, directly modeled after of_phandle_args, is used to pass a device-specific description of an interrupt.

struct irq_domain_ops¶: Methods for irq_domain objects

Definition:

struct irq_domain_ops {
    int (*match)(struct irq_domain *d, struct device_node *node, enum irq_domain_bus_token bus_token);
    int (*select)(struct irq_domain *d, struct irq_fwspec *fwspec, enum irq_domain_bus_token bus_token);
    int (*map)(struct irq_domain *d, unsigned int virq, irq_hw_number_t hw);
    void (*unmap)(struct irq_domain *d, unsigned int virq);
    int (*xlate)(struct irq_domain *d, struct device_node *node,const u32 *intspec, unsigned int intsize, unsigned long *out_hwirq, unsigned int *out_type);
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY;
    int (*alloc)(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs, void *arg);
    void (*free)(struct irq_domain *d, unsigned int virq, unsigned int nr_irqs);
    int (*activate)(struct irq_domain *d, struct irq_data *irqd, bool reserve);
    void (*deactivate)(struct irq_domain *d, struct irq_data *irq_data);
    int (*translate)(struct irq_domain *d, struct irq_fwspec *fwspec, unsigned long *out_hwirq, unsigned int *out_type);
#endif;
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS;
    void (*debug_show)(struct seq_file *m, struct irq_domain *d, struct irq_data *irqd, int ind);
#endif;
};

Members

match: Match an interrupt controller device node to a domain, returns 1 on a match
select: Match an interrupt controller fw specification. It is more generic than match as it receives a complete struct irq_fwspec. Therefore, select is preferred if provided. Returns 1 on a match.
map: Create or update a mapping between a virtual irq number and a hw irq number. This is called only once for a given mapping.
unmap: Dispose of such a mapping
xlate: Given a device tree node and interrupt specifier, decode the hardware irq number and linux irq type value.
alloc: Allocate nr_irqs interrupts starting from virq.
free: Free nr_irqs interrupts starting from virq.
activate: Activate one interrupt in HW (irqd). If reserve is set, only reserve the vector. If unset, assign the vector (called from request_irq()).
deactivate: Disarm one interrupt (irqd).
translate: Given fwspec, decode the hardware irq number (out_hwirq) and linux irq type value (out_type). This is a generalised xlate (over struct irq_fwspec) and is preferred if provided.
debug_show: For domains to show specific data for an interrupt in debugfs.

Description

Functions below are provided by the driver and called whenever a new mapping is created or an old mapping is disposed. The driver can then proceed to whatever internal data structures management is required. It also needs to setup the irq_desc when returning from map().

struct irq_domain¶: Hardware interrupt number translation object

Definition:

struct irq_domain {
    struct list_head                link;
    const char                      *name;
    const struct irq_domain_ops     *ops;
    void *host_data;
    unsigned int                    flags;
    unsigned int                    mapcount;
    struct mutex                    mutex;
    struct irq_domain               *root;
    struct fwnode_handle            *fwnode;
    enum irq_domain_bus_token       bus_token;
    struct irq_domain_chip_generic  *gc;
    struct device                   *dev;
    struct device                   *pm_dev;
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY;
    struct irq_domain               *parent;
#endif;
#ifdef CONFIG_GENERIC_MSI_IRQ;
    const struct msi_parent_ops     *msi_parent_ops;
#endif;
    void (*exit)(struct irq_domain *d);
    irq_hw_number_t hwirq_max;
    unsigned int                    revmap_size;
    struct radix_tree_root          revmap_tree;
    struct irq_data __rcu           *revmap[] ;
};

Members

link: Element in global irq_domain list.
name: Name of interrupt domain
ops: Pointer to irq_domain methods
host_data: Private data pointer for use by owner. Not touched by irq_domain core code.
flags: Per irq_domain flags
mapcount: The number of mapped interrupts
mutex: Domain lock, hierarchical domains use root domain’s lock
root: Pointer to root domain, or containing structure if non-hierarchical
fwnode: Pointer to firmware node associated with the irq_domain. Pretty easy to swap it for the of_node via the irq_domain_get_of_node accessor
bus_token: fwnode’s device_node might be used for several irq domains. But in connection with bus_token, the pair shall be unique in a system.
gc: Pointer to a list of generic chips. There is a helper function for setting up one or more generic chips for interrupt controllers drivers using the generic chip library which uses this pointer.
dev: Pointer to the device which instantiated the irqdomain With per device irq domains this is not necessarily the same as pm_dev.
pm_dev: Pointer to a device that can be utilized for power management purposes related to the irq domain.
parent: Pointer to parent irq_domain to support hierarchy irq_domains
msi_parent_ops: Pointer to MSI parent domain methods for per device domain init
exit: Function called when the domain is destroyed
hwirq_max: Top limit for the HW irq number. Especially to avoid conflicts/failures with reserved HW irqs. Can be ~0.
revmap_size: Size of the linear map table revmap
revmap_tree: Radix map tree for hwirqs that don’t fit in the linear map
revmap: Linear table of irq_data pointers

Description

Optional elements: Revmap data, used internally by the irq domain code:

struct irq_domain_info¶: Domain information structure

Definition:

struct irq_domain_info {
    struct fwnode_handle                    *fwnode;
    unsigned int                            domain_flags;
    unsigned int                            size;
    irq_hw_number_t hwirq_max;
    int direct_max;
    unsigned int                            hwirq_base;
    unsigned int                            virq_base;
    enum irq_domain_bus_token               bus_token;
    const char                              *name_suffix;
    const struct irq_domain_ops             *ops;
    void *host_data;
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY;
    struct irq_domain                       *parent;
#endif;
    struct irq_domain_chip_generic_info     *dgc_info;
    int (*init)(struct irq_domain *d);
    void (*exit)(struct irq_domain *d);
};

Members

fwnode: firmware node for the interrupt controller
domain_flags: Additional flags to add to the domain flags
size: Size of linear map; 0 for radix mapping only
hwirq_max: Maximum number of interrupts supported by controller
direct_max: Maximum value of direct maps; Use ~0 for no limit; 0 for no direct mapping
hwirq_base: The first hardware interrupt number (legacy domains only)
virq_base: The first Linux interrupt number for legacy domains to immediately associate the interrupts after domain creation
bus_token: Domain bus token
name_suffix: Optional name suffix to avoid collisions when multiple domains are added using same fwnode
ops: Domain operation callbacks
host_data: Controller private data pointer
parent: Pointer to the parent irq domain used in a hierarchy domain
dgc_info: Geneneric chip information structure pointer used to create generic chips for the domain if not NULL.
init: Function called when the domain is created. Allow to do some additional domain initialisation.
exit: Function called when the domain is destroyed. Allow to do some additional cleanup operation.

struct irq_domain *irq_domain_create_linear(struct fwnode_handle *fwnode, unsigned int size, const struct irq_domain_ops *ops, void *host_data)¶: Allocate and register a linear revmap irq_domain.

Parameters

struct fwnode_handle *fwnode: pointer to interrupt controller’s FW node.
unsigned int size: Number of interrupts in the domain.
const struct irq_domain_ops *ops: map/unmap domain callbacks
void *host_data: Controller private data pointer

Return

Newly created irq_domain

unsigned int irq_create_mapping(struct irq_domain *domain, irq_hw_number_t hwirq)¶: Map a hardware interrupt into linux irq space

Parameters

struct irq_domain *domain: domain owning this hardware interrupt or NULL for default domain
irq_hw_number_t hwirq: hardware irq number in that domain space

Description

Only one mapping per hardware interrupt is permitted.

If the sense/trigger is to be specified, set_irq_type() should be called on the number returned from that call.

Return

Linux irq number or 0 on error

struct irq_desc *irq_resolve_mapping(struct irq_domain *domain, irq_hw_number_t hwirq)¶: Find a linux irq from a hw irq number.

Parameters

struct irq_domain *domain: domain owning this hardware interrupt
irq_hw_number_t hwirq: hardware irq number in that domain space

Return

Interrupt descriptor

unsigned int irq_find_mapping(struct irq_domain *domain, irq_hw_number_t hwirq)¶: Find a linux irq from a hw irq number.

Parameters

struct irq_domain *domain: domain owning this hardware interrupt
irq_hw_number_t hwirq: hardware irq number in that domain space

Return

Linux irq number or 0 if not found

struct irq_domain *irq_domain_create_hierarchy(struct irq_domain *parent, unsigned int flags, unsigned int size, struct fwnode_handle *fwnode, const struct irq_domain_ops *ops, void *host_data)¶: Add a irqdomain into the hierarchy

Parameters

struct irq_domain *parent: Parent irq domain to associate with the new domain
unsigned int flags: Irq domain flags associated to the domain
unsigned int size: Size of the domain. See below
struct fwnode_handle *fwnode: Optional fwnode of the interrupt controller
const struct irq_domain_ops *ops: Pointer to the interrupt domain callbacks
void *host_data: Controller private data pointer

Description

If size is 0 a tree domain is created, otherwise a linear domain.

If successful the parent is associated to the new domain and the domain flags are set.

Return

A pointer to IRQ domain, or NULL on failure.

int irq_domain_alloc_irqs(struct irq_domain *domain, unsigned int nr_irqs, int node, void *arg)¶: Allocate IRQs from domain

Parameters

struct irq_domain *domain: domain to allocate from
unsigned int nr_irqs: number of IRQs to allocate
int node: NUMA node id for memory allocation
void *arg: domain specific argument

Description

See __irq_domain_alloc_irqs()’ documentation.

struct fwnode_handle *__irq_domain_alloc_fwnode(unsigned int type, int id, const char *name, phys_addr_t *pa)¶: Allocate a fwnode_handle suitable for identifying an irq domain

Parameters

unsigned int type: Type of irqchip_fwnode. See linux/irqdomain.h
int id: Optional user provided id if name != NULL
const char *name: Optional user provided domain name
phys_addr_t *pa: Optional user-provided physical address

Description

Allocate a struct irqchip_fwid, and return a pointer to the embedded fwnode_handle (or NULL on failure).

Note

The types IRQCHIP_FWNODE_NAMED and IRQCHIP_FWNODE_NAMED_ID are solely to transport name information to irqdomain creation code. The node is not stored. For other types the pointer is kept in the irq domain struct.

void irq_domain_free_fwnode(struct fwnode_handle *fwnode)¶: Free a non-OF-backed fwnode_handle

Parameters

struct fwnode_handle *fwnode: fwnode_handle to free

Description

Free a fwnode_handle allocated with irq_domain_alloc_fwnode.

struct irq_domain *irq_domain_instantiate(const struct irq_domain_info *info)¶: Instantiate a new irq domain data structure

Parameters

const struct irq_domain_info *info: Domain information pointer pointing to the information for this domain

Return

A pointer to the instantiated irq domain or an ERR_PTR value.

void irq_domain_remove(struct irq_domain *domain)¶: Remove an irq domain.

Parameters

struct irq_domain *domain: domain to remove

Description

This routine is used to remove an irq domain. The caller must ensure that all mappings within the domain have been disposed of prior to use, depending on the revmap type.

struct irq_domain *irq_domain_create_simple(struct fwnode_handle *fwnode, unsigned int size, unsigned int first_irq, const struct irq_domain_ops *ops, void *host_data)¶: Register an irq_domain and optionally map a range of irqs

Parameters

struct fwnode_handle *fwnode: firmware node for the interrupt controller
unsigned int size: total number of irqs in mapping
unsigned int first_irq: first number of irq block assigned to the domain, pass zero to assign irqs on-the-fly. If first_irq is non-zero, then pre-map all of the irqs in the domain to virqs starting at first_irq.
const struct irq_domain_ops *ops: domain callbacks
void *host_data: Controller private data pointer

Description

Allocates an irq_domain, and optionally if first_irq is positive then also allocate irq_descs and map all of the hwirqs to virqs starting at first_irq.

This is intended to implement the expected behaviour for most interrupt controllers. If device tree is used, then first_irq will be 0 and irqs get mapped dynamically on the fly. However, if the controller requires static virq assignments (non-DT boot) then it will set that up correctly.

struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec, enum irq_domain_bus_token bus_token)¶: Locates a domain for a given fwspec

Parameters

struct irq_fwspec *fwspec: FW specifier for an interrupt
enum irq_domain_bus_token bus_token: domain-specific data

void irq_set_default_domain(struct irq_domain *domain)¶: Set a “default” irq domain

Parameters

struct irq_domain *domain: default domain pointer

Description

For convenience, it’s possible to set a “default” domain that will be used whenever NULL is passed to irq_create_mapping(). It makes life easier for platforms that want to manipulate a few hard coded interrupt numbers that aren’t properly represented in the device-tree.

struct irq_domain *irq_get_default_domain(void)¶: Retrieve the “default” irq domain

Parameters

void: no arguments

Return

the default domain, if any.

Description

Modern code should never use this. This should only be used on systems that cannot implement a firmware->fwnode mapping (which both DT and ACPI provide).

unsigned int irq_create_direct_mapping(struct irq_domain *domain)¶: Allocate an irq for direct mapping

Parameters

struct irq_domain *domain: domain to allocate the irq for or NULL for default domain

Description

This routine is used for irq controllers which can choose the hardware interrupt numbers they generate. In such a case it’s simplest to use the linux irq as the hardware interrupt number. It still uses the linear or radix tree to store the mapping, but the irq controller can optimize the revmap path by using the hwirq directly.

unsigned int irq_create_mapping_affinity(struct irq_domain *domain, irq_hw_number_t hwirq, const struct irq_affinity_desc *affinity)¶: Map a hardware interrupt into linux irq space

Parameters

struct irq_domain *domain: domain owning this hardware interrupt or NULL for default domain
irq_hw_number_t hwirq: hardware irq number in that domain space
const struct irq_affinity_desc *affinity: irq affinity

Description

Only one mapping per hardware interrupt is permitted. Returns a linux irq number. If the sense/trigger is to be specified, set_irq_type() should be called on the number returned from that call.

void irq_dispose_mapping(unsigned int virq)¶: Unmap an interrupt

Parameters

unsigned int virq: linux irq number of the interrupt to unmap

struct irq_desc *__irq_resolve_mapping(struct irq_domain *domain, irq_hw_number_t hwirq, unsigned int *irq)¶: Find a linux irq from a hw irq number.

Parameters

struct irq_domain *domain: domain owning this hardware interrupt
irq_hw_number_t hwirq: hardware irq number in that domain space
unsigned int *irq: optional pointer to return the Linux irq if required

Description

Returns the interrupt descriptor.

int irq_domain_xlate_onecell(struct irq_domain *d, struct device_node *ctrlr, const u32 *intspec, unsigned int intsize, unsigned long *out_hwirq, unsigned int *out_type)¶: Generic xlate for direct one cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct device_node *ctrlr: The device tree node for the device whose interrupt is translated
const u32 *intspec: The interrupt specifier data from the device tree
unsigned int intsize: The number of entries in intspec
unsigned long *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

Description

Device Tree IRQ specifier translation function which works with one cell bindings where the cell value maps directly to the hwirq number.

int irq_domain_xlate_twocell(struct irq_domain *d, struct device_node *ctrlr, const u32 *intspec, unsigned int intsize, irq_hw_number_t *out_hwirq, unsigned int *out_type)¶: Generic xlate for direct two cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct device_node *ctrlr: The device tree node for the device whose interrupt is translated
const u32 *intspec: The interrupt specifier data from the device tree
unsigned int intsize: The number of entries in intspec
irq_hw_number_t *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

Description

Device Tree IRQ specifier translation function which works with two cell bindings where the cell values map directly to the hwirq number and linux irq flags.

int irq_domain_xlate_twothreecell(struct irq_domain *d, struct device_node *ctrlr, const u32 *intspec, unsigned int intsize, irq_hw_number_t *out_hwirq, unsigned int *out_type)¶: Generic xlate for direct two or three cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct device_node *ctrlr: The device tree node for the device whose interrupt is translated
const u32 *intspec: The interrupt specifier data from the device tree
unsigned int intsize: The number of entries in intspec
irq_hw_number_t *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

Description

Device Tree interrupt specifier translation function for two or three cell bindings, where the cell values map directly to the hardware interrupt number and the type specifier.

int irq_domain_xlate_onetwocell(struct irq_domain *d, struct device_node *ctrlr, const u32 *intspec, unsigned int intsize, unsigned long *out_hwirq, unsigned int *out_type)¶: Generic xlate for one or two cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct device_node *ctrlr: The device tree node for the device whose interrupt is translated
const u32 *intspec: The interrupt specifier data from the device tree
unsigned int intsize: The number of entries in intspec
unsigned long *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

Description

Device Tree IRQ specifier translation function which works with either one or two cell bindings where the cell values map directly to the hwirq number and linux irq flags.

Note

don’t use this function unless your interrupt controller explicitly supports both one and two cell bindings. For the majority of controllers the _onecell() or _twocell() variants above should be used.

int irq_domain_translate_onecell(struct irq_domain *d, struct irq_fwspec *fwspec, unsigned long *out_hwirq, unsigned int *out_type)¶: Generic translate for direct one cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct irq_fwspec *fwspec: The firmware interrupt specifier to translate
unsigned long *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

int irq_domain_translate_twocell(struct irq_domain *d, struct irq_fwspec *fwspec, unsigned long *out_hwirq, unsigned int *out_type)¶: Generic translate for direct two cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct irq_fwspec *fwspec: The firmware interrupt specifier to translate
unsigned long *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

Description

Device Tree IRQ specifier translation function which works with two cell bindings where the cell values map directly to the hwirq number and linux irq flags.

int irq_domain_translate_twothreecell(struct irq_domain *d, struct irq_fwspec *fwspec, unsigned long *out_hwirq, unsigned int *out_type)¶: Generic translate for direct two or three cell bindings

Parameters

struct irq_domain *d: Interrupt domain involved in the translation
struct irq_fwspec *fwspec: The firmware interrupt specifier to translate
unsigned long *out_hwirq: Pointer to storage for the hardware interrupt number
unsigned int *out_type: Pointer to storage for the interrupt type

Description

Firmware interrupt specifier translation function for two or three cell specifications, where the parameter values map directly to the hardware interrupt number and the type specifier.

void irq_domain_reset_irq_data(struct irq_data *irq_data)¶: Clear hwirq, chip and chip_data in irq_data

Parameters

struct irq_data *irq_data: The pointer to irq_data

int irq_domain_disconnect_hierarchy(struct irq_domain *domain, unsigned int virq)¶: Mark the first unused level of a hierarchy

Parameters

struct irq_domain *domain: IRQ domain from which the hierarchy is to be disconnected
unsigned int virq: IRQ number where the hierarchy is to be trimmed

Description

Marks the virq level belonging to domain as disconnected. Returns -EINVAL if virq doesn’t have a valid irq_data pointing to domain.

Its only use is to be able to trim levels of hierarchy that do not have any real meaning for this interrupt, and that the driver marks as such from its .alloc() callback.

struct irq_data *irq_domain_get_irq_data(struct irq_domain *domain, unsigned int virq)¶: Get irq_data associated with virq and domain

Parameters

struct irq_domain *domain: domain to match
unsigned int virq: IRQ number to get irq_data

int irq_domain_set_hwirq_and_chip(struct irq_domain *domain, unsigned int virq, irq_hw_number_t hwirq, const struct irq_chip *chip, void *chip_data)¶: Set hwirq and irqchip of virq at domain

Parameters

struct irq_domain *domain: Interrupt domain to match
unsigned int virq: IRQ number
irq_hw_number_t hwirq: The hwirq number
const struct irq_chip *chip: The associated interrupt chip
void *chip_data: The associated chip data

void irq_domain_set_info(struct irq_domain *domain, unsigned int virq, irq_hw_number_t hwirq, const struct irq_chip *chip, void *chip_data, irq_flow_handler_t handler, void *handler_data, const char *handler_name)¶: Set the complete data for a virq in domain

Parameters

struct irq_domain *domain: Interrupt domain to match
unsigned int virq: IRQ number
irq_hw_number_t hwirq: The hardware interrupt number
const struct irq_chip *chip: The associated interrupt chip
void *chip_data: The associated interrupt chip data
irq_flow_handler_t handler: The interrupt flow handler
void *handler_data: The interrupt flow handler data
const char *handler_name: The interrupt handler name

void irq_domain_free_irqs_common(struct irq_domain *domain, unsigned int virq, unsigned int nr_irqs)¶: Clear irq_data and free the parent

Parameters

struct irq_domain *domain: Interrupt domain to match
unsigned int virq: IRQ number to start with
unsigned int nr_irqs: The number of irqs to free

int __irq_domain_alloc_irqs(struct irq_domain *domain, int irq_base, unsigned int nr_irqs, int node, void *arg, bool realloc, const struct irq_affinity_desc *affinity)¶: Allocate IRQs from domain

Parameters

struct irq_domain *domain: domain to allocate from
int irq_base: allocate specified IRQ number if irq_base >= 0
unsigned int nr_irqs: number of IRQs to allocate
int node: NUMA node id for memory allocation
void *arg: domain specific argument
bool realloc: IRQ descriptors have already been allocated if true
const struct irq_affinity_desc *affinity: Optional irq affinity mask for multiqueue devices

Description

Allocate IRQ numbers and initialized all data structures to support hierarchy IRQ domains. Parameter realloc is mainly to support legacy IRQs. Returns error code or allocated IRQ number

The whole process to setup an IRQ has been split into two steps. The first step, __irq_domain_alloc_irqs(), is to allocate IRQ descriptor and required hardware resources. The second step, irq_domain_activate_irq(), is to program the hardware with preallocated resources. In this way, it’s easier to rollback when failing to allocate resources.

int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg)¶: Push a domain in to the top of a hierarchy.

Parameters

struct irq_domain *domain: Domain to push.
int virq: Irq to push the domain in to.
void *arg: Passed to the irq_domain_ops alloc() function.

Description

For an already existing irqdomain hierarchy, as might be obtained via a call to pci_enable_msix(), add an additional domain to the head of the processing chain. Must be called before request_irq() has been called.

int irq_domain_pop_irq(struct irq_domain *domain, int virq)¶: Remove a domain from the top of a hierarchy.

Parameters

struct irq_domain *domain: Domain to remove.
int virq: Irq to remove the domain from.

Description

Undo the effects of a call to irq_domain_push_irq(). Must be called either before request_irq() or after free_irq().

int irq_domain_alloc_irqs_parent(struct irq_domain *domain, unsigned int irq_base, unsigned int nr_irqs, void *arg)¶: Allocate interrupts from parent domain

Parameters

struct irq_domain *domain: Domain below which interrupts must be allocated
unsigned int irq_base: Base IRQ number
unsigned int nr_irqs: Number of IRQs to allocate
void *arg: Allocation data (arch/domain specific)

void irq_domain_free_irqs_parent(struct irq_domain *domain, unsigned int irq_base, unsigned int nr_irqs)¶: Free interrupts from parent domain

Parameters

struct irq_domain *domain: Domain below which interrupts must be freed
unsigned int irq_base: Base IRQ number
unsigned int nr_irqs: Number of IRQs to free

Internal Functions Provided¶

This chapter contains the autogenerated documentation of the internal functions.

void irq_domain_free_irqs_top(struct irq_domain *domain, unsigned int virq, unsigned int nr_irqs)¶: Clear handler and handler data, clear irqdata and free parent

Parameters

struct irq_domain *domain: Interrupt domain to match
unsigned int virq: IRQ number to start with
unsigned int nr_irqs: The number of irqs to free

void irq_domain_free_irqs(unsigned int virq, unsigned int nr_irqs)¶: Free IRQ number and associated data structures

Parameters

unsigned int virq: base IRQ number
unsigned int nr_irqs: number of IRQs to free

int irq_domain_activate_irq(struct irq_data *irq_data, bool reserve)¶: Call domain_ops->activate recursively to activate interrupt

Parameters

struct irq_data *irq_data: Outermost irq_data associated with interrupt
bool reserve: If set only reserve an interrupt vector instead of assigning one

Description

This is the second step to call domain_ops->activate to program interrupt controllers, so the interrupt could actually get delivered.

void irq_domain_deactivate_irq(struct irq_data *irq_data)¶: Call domain_ops->deactivate recursively to deactivate interrupt

Parameters

struct irq_data *irq_data: outermost irq_data associated with interrupt

Description

It calls domain_ops->deactivate to program interrupt controllers to disable interrupt delivery.

The Linux Kernel

Contents

This Page

The irq_domain Interrupt Number Mapping Library¶

irq_domain Usage¶

Types of irq_domain Mappings¶

Linear¶

Tree¶

No Map¶

Legacy¶

Hierarchy IRQ Domain¶

Stacked irq_chip¶

Debugging¶

Structures and Public Functions Provided¶

Internal Functions Provided¶