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IOInterruptEventSource Class Reference

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IOInterruptEventSource

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.

Inheritance


Not Applicable

Conforms To


Not Applicable

Import Statement


Not Applicable

Objective-C

@import Kernel;

Availability


Available in OS X v10.0 and later.
  • Pure Virtual member function used by IOWorkLoop for issueing a client calls.

    Declaration

    C++

    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.

    Declaration

    C++

    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

    Declaration

    C++

    virtual void disableInterruptOccurred( void *, IOService *nub, intind);

    Parameters

    nub

    Where did the interrupt originate from

    ind

    What is this interrupts index within 'nub'.

  • Enable event source.

    Declaration

    C++

    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.

    Declaration

    C++

    virtual void free();

  • Get'ter for $link autoDisable variable.

    Declaration

    C++

    virtual bool getAutoDisable() const;

    Return Value

    value of autoDisable.

  • Get'ter for $link intIndex interrupt index variable.

    Declaration

    C++

    virtual int getIntIndex() const;

    Return Value

    value of intIndex.

  • Get'ter for $link provider variable.

    Declaration

    C++

    virtual const IOService *getProvider() const;

    Return Value

    value of provider.

  • Primary initialiser for the IOInterruptEventSource class.

    Declaration

    C++

    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.

  • Factory function for IOInterruptEventSources creation and initialisation.

    Declaration

    C++

    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.

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

    Declaration

    C++

    virtual void interruptOccurred( void *, IOService *nub, intind);

    Parameters

    nub

    Where did the interrupt originate from

    ind

    What is this interrupts index within 'nub'.

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

    Declaration

    C++

    virtual void normalInterruptOccurred( void *, IOService *nub, intind);

    Parameters

    nub

    Where did the interrupt originate from

    ind

    What is this interrupts index within 'nub'.

  • Sub-class implementation of setWorkLoop method.

    Declaration

    C++

    virtual void setWorkLoop( IOWorkLoop *inWorkLoop);

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

    Declaration

    C++

    IOReturn warmCPU( uint64_tabstime);

    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

  • Declaration

    C++

    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.

    Import Statement

    Objective-C

    #include <IOCommandGate.h>;

    Availability

    Available in OS X v10.0 through OS X v10.5.

Constants

  • Declaration

    CPlusPlus

    #define IOInterruptEventAction IOInterruptEventSource::Action

    Constants

    • IOInterruptEventAction

      IOInterruptEventAction

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

      Available in OS X v10.0 and later.

  • Data Types

    • Declaration

      C++

      struct ExpansionData { };

      Discussion

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

    Instance Variables

    • Reserved for future use. (Internal use only)

      Declaration

      C++

      ExpansionData *reserved;

    • IOService that provides interrupts for delivery.

      Declaration

      C++

      IOService *provider;

    • Current count of produced interrupts that have been received.

      Declaration

      C++

      volatile unsigned int producerCount;

    • Declaration

      C++

      int intIndex;

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

      Declaration

      C++

      bool explicitDisable;

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

      Declaration

      C++

      unsigned int consumerCount;

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

      Declaration

      C++

      bool autoDisable;