IOInterruptEventSource

Inherits from
IOEventSource
Availability
Available in OS X v10.0 and later.
Declared in
IOCommandGate.h
IOInterruptEventSource.h

Overview

Event source for interrupt delivery to work-loop based drivers.

The IOInterruptEventSource is a generic object that delivers calls interrupt routines in it's client in a guaranteed single-threaded manner. IOInterruptEventSource is part of the IOKit $link IOWorkLoop infrastructure where the semantic that one and only one action method is executing within a work-loops event chain.

When the action method is called in the client member function will receive 2 arguments, (IOEventSource *) sender and (int) count, See $link IOInterruptEventSource::Action. Where sender will be reference to the interrupt that occurred and the count will be computed by the difference between the $link producerCount and $link consumerCount. This number may not be reliable as no attempt is made to adjust for around the world type problems but is provided for general information and statistic gathering.

In general a client will use the factory member function to create and initialise the event source and then add it to their work-loop. It is the work loop's responsiblity to maintain the new event source in it's event chain. See $link IOWorkLoop.

An interrupt event source attaches itself to the given provider's interrupt source at initialisation time. At this time it determines if it is connected to a level or edge triggered interrupt. If the interrupt is an level triggered interrupt the event source automatically disables the interrupt source at primary interrupt time and after it call's the client it automatically reenables the interrupt. This action is fairly expensive but it is 100% safe and defaults sensibly so that the driver writer does not have to implement type dependant interrupt routines. So to repeat, the driver writer does not have to be concerned by the actual underlying interrupt mechanism as the event source hides the complexity.

Saying this if the hardware is a multi-device card, for instance a 4 port NIC, where all of the devices are sharing one level triggered interrupt AND it is possible to determine each port's interrupt state non-destructively then the $link IOFilterInterruptEventSource would be a better choice.

Warning: All IOInterruptEventSources are created in the disabled state. If you want to actually schedule interrupt delivery do not forget to enable the source.

Tasks

Miscellaneous

Instance Methods

checkForWork

Pure Virtual member function used by IOWorkLoop for issueing a client calls.

virtual bool checkForWork();
Return Value

Return true if this function needs to be called again before all its outstanding events have been processed.

Discussion

This function called when the work-loop is ready to check for any work to do and then to call out the owner/action.

disable

Disable event source.

virtual void disable();
Discussion

A subclass implementation is expected to respect the enabled state when checkForWork is called.

disableInterruptOccurred

Functions that get called by the interrupt controller.See $link IOService::registerInterrupt

virtual void disableInterruptOccurred( void *, IOService *nub, int ind);
Parameters
nub

Where did the interrupt originate from

ind

What is this interrupts index within 'nub'.

enable

Enable event source.

virtual void enable();
Discussion

A subclass implementation is expected to respect the enabled state when checkForWork is called. Calling this function will cause the work-loop to be signalled so that a checkForWork is performed.

free

Sub-class implementation of free method, disconnects from the interrupt source.

virtual void free();

getAutoDisable

Get'ter for $link autoDisable variable.

virtual bool getAutoDisable() const;
Return Value

value of autoDisable.

getIntIndex

Get'ter for $link intIndex interrupt index variable.

virtual int getIntIndex() const;
Return Value

value of intIndex.

getProvider

Get'ter for $link provider variable.

virtual const IOService *getProvider() const;
Return Value

value of provider.

init

Primary initialiser for the IOInterruptEventSource class.

virtual bool init( OSObject *owner, Action action, IOService *provider = 0, int intIndex = 0);
Parameters
owner

Owning client of the new event source.

action

'C' Function to call when something happens.

provider

IOService that represents the interrupt source. Defaults to 0. When no provider is defined the event source assumes that the client will in some manner call the interruptOccured method explicitly. This will start the ball rolling for safe delivery of asynchronous event's into the driver.

intIndex

The index of the interrupt within the provider's interrupt sources. Defaults to 0, i.e. the first interrupt in the provider.

Return Value

true if the inherited classes and this instance initialise successfully.

interruptEventSource

Factory function for IOInterruptEventSources creation and initialisation.

static IOInterruptEventSource * interruptEventSource( OSObject *owner, Action action, IOService *provider = 0, int intIndex = 0);
Parameters
owner

Owning client of the new event source.

action

'C' Function to call when something happens.

provider

IOService that represents the interrupt source. Defaults to 0. When no provider is defined the event source assumes that the client will in some manner call the interruptOccured method explicitly. This will start the ball rolling for safe delivery of asynchronous event's into the driver.

intIndex

The index of the interrupt within the provider's interrupt sources. Defaults to 0, i.e. the first interrupt in the provider.

Return Value

A new interrupt event source if successfully created and initialised, 0 otherwise.

interruptOccurred

Functions that get called by the interrupt controller. See $link IOService::registerInterrupt

virtual void interruptOccurred( void *, IOService *nub, int ind);
Parameters
nub

Where did the interrupt originate from

ind

What is this interrupts index within 'nub'.

normalInterruptOccurred

Functions that get called by the interrupt controller.See $link IOService::registerInterrupt

virtual void normalInterruptOccurred( void *, IOService *nub, int ind);
Parameters
nub

Where did the interrupt originate from

ind

What is this interrupts index within 'nub'.

setWorkLoop

Sub-class implementation of setWorkLoop method.

virtual void setWorkLoop( IOWorkLoop *inWorkLoop);

warmCPU

Tries to reduce latency for an interrupt which will be received near a specified time.

IOReturn warmCPU( uint64_t abstime);
Parameters
abstime

Time at which interrupt is expected.

Discussion

Warms up a CPU in advance of an interrupt so that the interrupt may be serviced with predictable latency. The warm-up is not periodic; callers should call warmCPU once in advance of each interrupt. It is recommended that requests be issues in serial (i.e. each after the target for the previous call has elapsed), as there is a systemwide cap on the number of outstanding requests. This routine may be disruptive to the system if used with very small intervals between requests; it should be used only in cases where interrupt latency is absolutely critical, and tens or hundreds of milliseconds between targets is the expected time scale. NOTE: it is not safe to call this method with interrupts disabled.

Callbacks

Action

typedef void ( *Action)(
   OSObject *,
   IOInterruptEventSource *,
   int count);

Parameters
owner

Pointer to client instance.

sender

Pointer to generation interrupt event source.

count

Number of interrupts seen before delivery.

Discussion

'C' pointer prototype of functions that are called in a single threaded context when an interrupt occurs.

Availability
Declared In
IOCommandGate.h

Constants

Miscellaneous Defines

   
#define IOInterruptEventAction IOInterruptEventSource::Action
Constants
IOInterruptEventAction

Backward compatibilty define for the old non-class scoped type definition. See $link IOInterruptEventSource::Action

Available in OS X v10.0 and later.

Declared in IOInterruptEventSource.h.

ExpansionData

struct ExpansionData {
};
Discussion

This structure will be used to expand the capablilties of the IOWorkLoop in the future.

Instance Variables

autoDisable

bool autoDisable;

Do we need to automatically disable the interrupt source when we take an interrupt, i.e. we are level triggered.

consumerCount

unsigned int consumerCount;

Current count of produced interrupts that the owner has been informed of.

explicitDisable

bool explicitDisable;

Has the user expicitly disabled this event source, if so then do not overide their request when returning from the callout

intIndex

int intIndex;

producerCount

volatile unsigned int producerCount;

Current count of produced interrupts that have been received.

provider

IOService *provider;

IOService that provides interrupts for delivery.

reserved

ExpansionData *reserved;

Reserved for future use. (Internal use only)