Overview

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

Discussion

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.

Functions

checkForWork

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

disable

Disable event source.

disableInterruptOccurred

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

enable

Enable event source.

free

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

getAutoDisable

Get'ter for $link autoDisable variable.

getIntIndex

Get'ter for $link intIndex interrupt index variable.

getProvider

Get'ter for $link provider variable.

init

Primary initialiser for the IOInterruptEventSource class.

interruptEventSource

Factory function for IOInterruptEventSources creation and initialisation.

interruptOccurred

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

normalInterruptOccurred

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

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

protected

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 event source.

public

virtual void disable(); 

Discussion

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

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

public

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

Parameters

Enable event source.

public

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.

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

protected

virtual void free(); 

Get'ter for $link autoDisable variable.

public

virtual bool getAutoDisable() const; 

Return Value

value of autoDisable.

Get'ter for $link intIndex interrupt index variable.

public

virtual int getIntIndex() const; 

Return Value

value of intIndex.

Get'ter for $link provider variable.

public

virtual const IOService *getProvider() const; 

Return Value

value of provider.

Primary initialiser for the IOInterruptEventSource class.

public

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

Parameters

Return Value

true if the inherited classes and this instance initialise successfully.

Factory function for IOInterruptEventSources creation and initialisation.

public

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

Parameters

Return Value

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

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

public

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

Parameters

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

public

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

Parameters

Typedefs

Action

public

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

Fields

Discussion

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

Structs and Unions

ExpansionData

protected

struct ExpansionData {
}; 

Discussion

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

Member Data

autoDisable

consumerCount

explicitDisable

intIndex

producerCount

provider

reserved

protected

bool autoDisable; 

Discussion

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

protected

unsigned int consumerCount; 

Discussion

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

protected

bool explicitDisable; 

Discussion

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

protected

int intIndex; 

protected

volatile unsigned int producerCount; 

Discussion

Current count of produced interrupts that have been received.

protected

IOService *provider; 

Discussion

IOService that provides interrupts for delivery.

protected

ExpansionData *reserved; 

Discussion

Reserved for future use. (Internal use only)

Macro Definitions

IOInterruptEventAction

#define IOInterruptEventAction IOInterruptEventSource::Action 

Discussion

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

Last Updated: 2010-07-29