iokit/IOKit/IOEventSource.h

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23 Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  24 HISTORY
  25     1998-7-13   Godfrey van der Linden(gvdl)
  26         Created.
  27     1998-10-30  Godfrey van der Linden(gvdl)
  28         Converted to C++
  29 */
  30 #ifndef _IOKIT_IOEVENTSOURCE_H
  31 #define _IOKIT_IOEVENTSOURCE_H
  32
  33 #include <sys/cdefs.h>
  34
  35 #include <libkern/c++/OSObject.h>
  36
  37 #include <IOKit/IOLib.h>
  38 #include <IOKit/system.h>
  39 #include <IOKit/IOWorkLoop.h>
  40
  41
  42 __BEGIN_DECLS
  43 #include <mach/clock_types.h>
  44 #include <kern/clock.h>
  45 __END_DECLS
  46
  47 /*!
  48     @class IOEventSource : public OSObject
  49     @abstract Abstract class for all work-loop event sources.
  50     @discussion The IOEventSource declares the abstract super class that all
  51 event sources must inherit from if an IOWorkLoop is to receive events from them.
  52 <br><br>
  53         An event source can represent any event that should cause the work-loop of a
  54 device to wake up and perform work.  Two examples of event sources are the
  55 IOInterruptEventSource which delivers interrupt notifications and IOCommandGate
  56 which delivers command requests.
  57 <br><br>
  58         A kernel module can always use the work-loop model for serialising access to
  59 anything at all.  The IOEventSource is used for communicating events to the
  60 work-loop, and the chain of event sources should be used to walk the possible
  61 event sources and demultipex them.  Note a particular instance of an event
  62 source may only be a member of 1 linked list chain.  If you need to move it
  63 between chains than make sure it is removed from the original chain before
  64 attempting to move it.
  65 <br><br>
  66         The IOEventSource makes no attempt to maintain the consitency of it's internal data across multi-threading.  It is assumed that the user of these basic tools will protect the data that these objects represent in some sort of device wide instance lock.     For example the IOWorkLoop maintains the event chain by handing off change request to its own thread and thus single threading access to its state.
  67 <br><br>
  68         All subclasses of the IOEventSource are expected to implement the checkForWork() member function.
  69
  70 <br><br>
  71         checkForWork() is the key method in this class.  It is called by some work-loop when convienient and is expected to evaluate it's internal state and determine if an event has occurred since the last call.  In the case of an event having occurred then the instance defined target(owner)/action will be called.     The action is stored as an ordinary C function pointer but the first parameter is always the owner.  This means that a C++ member function can be used as an action function though this depends on the ABI.
  72 <br><br>
  73         Although the eventChainNext variable contains a reference to the next event source in the chain this reference is not retained.  The list 'owner' i.e. the client that creates the event, not the work-loop, is expected to retain the source.
  74 */
  75 class IOEventSource : public OSObject
  76 {
  77     OSDeclareAbstractStructors(IOEventSource)
  78     friend class IOWorkLoop;
  79
  80 public:
  81 /*!
  82     @typedef Action
  83     @discussion Placeholder type for C++ function overloading discrimination.
  84 As the all event sources require an action and it has to be stored somewhere
  85 and be of some type, this is that type.
  86     @param owner
  87         Target of the function, can be used as a refcon.  The owner is set
  88 during initialisation.   Note if a C++ function was specified this parameter
  89 is implicitly the first paramter in the target member function's parameter list.
  90 */
  91     typedef void (*Action)(OSObject *owner, ...);
  92
  93 /*! @defined IOEventSourceAction
  94     @discussion Backward compatibilty define for the old non-class scoped type definition.  See $link IOEventSource::Action */
  95  #define IOEventSourceAction IOEventSource::Action
  96
  97 protected:
  98 /*! @var eventChainNext
  99         The next event source in the event chain. nil at end of chain. */
 100     IOEventSource *eventChainNext;
 101
 102 /*! @var owner The owner object called when an event has been delivered. */
 103     OSObject *owner;
 104
 105 /*! @var action
 106         The action method called when an event has been delivered */
 107     Action action;
 108
 109 /*! @var enabled
 110         Is this event source enabled to deliver requests to the work-loop. */
 111     bool enabled;
 112
 113 /*! @var workLoop What is the work-loop for this event source. */
 114     IOWorkLoop *workLoop;
 115
 116 /*! @var refcon What ever the client wants to do, see $link setRefcon. */
 117     void *refcon;
 118
 119 /*! @struct ExpansionData
 120     @discussion This structure will be used to expand the capablilties of the IOEventSource in the future.
 121     */
 122     struct ExpansionData { };
 123
 124 /*! @var reserved
 125     Reserved for future use.  (Internal use only)  */
 126     ExpansionData *reserved;
 127
 128 /*! @function init
 129     @abstract Primary initialiser for the IOEventSource class.
 130     @param owner
 131         Owner of this instance of an event source.  Used as the first parameter
 132 of the action callout.  Owner will generally be an OSObject it doesn't have to
 133 be as no member functions will be called directly in it.  It can just be a
 134 refcon for a client routine.
 135     @param action
 136         Pointer to C call out function.  Action is a pointer to a C function
 137 that gets called when this event source has outstanding work.  It will usually
 138 be called by the checkForWork member function.  The first parameter of the
 139 action call out will always be the owner, this allows C++ member functions to
 140 be used as actions.  Defaults to 0.
 141     @result true if the inherited classes and this instance initialise
 142 successfully.
 143 */
 144     virtual bool init(OSObject *owner, IOEventSource::Action action = 0);
 145
 146 /*! @function checkForWork
 147     @abstract Pure Virtual member function used by IOWorkLoop for work
 148 scheduling.
 149     @discussion This function will be called to request a subclass to check
 150 it's internal state for any work to do and then to call out the owner/action.
 151     @result Return true if this function needs to be called again before all its outstanding events have been processed.
 152         */
 153     virtual bool checkForWork() = 0;
 154
 155 /*! @function setWorkLoop
 156     @abstract Set'ter for $link workLoop variable.
 157     @param workLoop
 158         Target work-loop of this event source instance.  A subclass of
 159 IOWorkLoop that at least reacts to signalWorkAvailable() and onThread functions.
 160 */
 161     virtual void setWorkLoop(IOWorkLoop *workLoop);
 162
 163 /*! @function setNext
 164     @abstract Set'ter for $link eventChainNext variable.
 165     @param next
 166         Pointer to another IOEventSource instance.
 167 */
 168     virtual void setNext(IOEventSource *next);
 169
 170 /*! @function getNext
 171     @abstract Get'ter for $link eventChainNext variable.
 172     @result value of eventChainNext.
 173 */
 174     virtual IOEventSource *getNext() const;
 175
 176
 177 protected:
 178     // Methods to access the IOWorkLoop exported fields
 179     /* inline */ void signalWorkAvailable();
 180         /* { workLoop->signalWorkAvailable(); }; */
 181     /* inline */ void openGate();
 182         /* { workLoop->openGate(); }; */
 183     /* inline */ void closeGate();
 184         /* { workLoop->closeGate(); }; */
 185     /* inline */ bool tryCloseGate();
 186         /* { return workLoop->tryCloseGate(); }; */
 187     /* inline */ int sleepGate(void *event, UInt32 type);
 188         /* { return workLoop->sleepGate(event, type); }; */
 189     /* inline */ void wakeupGate(void *event, bool oneThread);
 190         /* { workLoop->wakeupGate(event, oneThread); }; */
 191
 192 public:
 193 /*! @function setAction
 194     @abstract Set'ter for $link action variable.
 195     @param action Pointer to a C function of type IOEventSource::Action. */
 196     virtual void setAction(IOEventSource::Action action);
 197
 198 /*! @function getAction
 199     @abstract Get'ter for $link action variable.
 200     @result value of action. */
 201     virtual IOEventSource::Action getAction() const;
 202
 203 /*! @function enable
 204     @abstract Enable event source.
 205     @discussion A subclass implementation is expected to respect the enabled
 206 state when checkForWork is called.  Calling this function will cause the
 207 work-loop to be signalled so that a checkForWork is performed. */
 208     virtual void enable();
 209
 210 /*! @function disable
 211     @abstract Disable event source.
 212     @discussion A subclass implementation is expected to respect the enabled
 213 state when checkForWork is called. */
 214     virtual void disable();
 215
 216 /*! @function isEnabled
 217     @abstract Get'ter for $link enable variable.
 218     @result true if enabled. */
 219     virtual bool isEnabled() const;
 220
 221 /*! @function getWorkLoop
 222     @abstract Get'ter for $link workLoop variable.
 223     @result value of workLoop. */
 224     virtual IOWorkLoop *getWorkLoop() const;
 225
 226 /*! @function onThread
 227     @abstract Convenience function for workLoop->onThread.
 228     @result true if called on the work-loop thread.
 229 */
 230     virtual bool onThread() const;
 231
 232 private:
 233     OSMetaClassDeclareReservedUnused(IOEventSource, 0);
 234     OSMetaClassDeclareReservedUnused(IOEventSource, 1);
 235     OSMetaClassDeclareReservedUnused(IOEventSource, 2);
 236     OSMetaClassDeclareReservedUnused(IOEventSource, 3);
 237     OSMetaClassDeclareReservedUnused(IOEventSource, 4);
 238     OSMetaClassDeclareReservedUnused(IOEventSource, 5);
 239     OSMetaClassDeclareReservedUnused(IOEventSource, 6);
 240     OSMetaClassDeclareReservedUnused(IOEventSource, 7);
 241 };
 242
 243 #endif /* !_IOKIT_IOEVENTSOURCE_H */