iokit/IOKit/IOEventSource.h

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26 Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  27 HISTORY
  28     1998-7-13   Godfrey van der Linden(gvdl)
  29         Created.
  30     1998-10-30  Godfrey van der Linden(gvdl)
  31         Converted to C++
  32 */
  33 #ifndef _IOKIT_IOEVENTSOURCE_H
  34 #define _IOKIT_IOEVENTSOURCE_H
  35
  36 #include <sys/cdefs.h>
  37
  38 #include <libkern/c++/OSObject.h>
  39
  40 #include <IOKit/IOLib.h>
  41 #include <IOKit/system.h>
  42 #include <IOKit/IOWorkLoop.h>
  43
  44
  45 __BEGIN_DECLS
  46 #include <mach/clock_types.h>
  47 #include <kern/clock.h>
  48 __END_DECLS
  49
  50 /*!
  51     @class IOEventSource : public OSObject
  52     @abstract Abstract class for all work-loop event sources.
  53     @discussion The IOEventSource declares the abstract super class that all
  54 event sources must inherit from if an IOWorkLoop is to receive events from them.
  55 <br><br>
  56         An event source can represent any event that should cause the work-loop of a
  57 device to wake up and perform work.  Two examples of event sources are the
  58 IOInterruptEventSource which delivers interrupt notifications and IOCommandGate
  59 which delivers command requests.
  60 <br><br>
  61         A kernel module can always use the work-loop model for serialising access to
  62 anything at all.  The IOEventSource is used for communicating events to the
  63 work-loop, and the chain of event sources should be used to walk the possible
  64 event sources and demultipex them.  Note a particular instance of an event
  65 source may only be a member of 1 linked list chain.  If you need to move it
  66 between chains than make sure it is removed from the original chain before
  67 attempting to move it.
  68 <br><br>
  69         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.
  70 <br><br>
  71         All subclasses of the IOEventSource are expected to implement the checkForWork() member function.
  72
  73 <br><br>
  74         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 occured 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.
  75 <br><br>
  76         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.
  77 */
  78 class IOEventSource : public OSObject
  79 {
  80     OSDeclareAbstractStructors(IOEventSource)
  81     friend class IOWorkLoop;
  82
  83 public:
  84 /*!
  85     @typedef Action
  86     @discussion Placeholder type for C++ function overloading discrimination.
  87 As the all event sources require an action and it has to be stored somewhere
  88 and be of some type, this is that type.
  89     @param owner
  90         Target of the function, can be used as a refcon.  The owner is set
  91 during initialisation.   Note if a C++ function was specified this parameter
  92 is implicitly the first paramter in the target member function's parameter list.
  93 */
  94     typedef void (*Action)(OSObject *owner, ...);
  95
  96 /*! @defined IOEventSourceAction
  97     @discussion Backward compatibilty define for the old non-class scoped type definition.  See $link IOEventSource::Action */
  98  #define IOEventSourceAction IOEventSource::Action
  99
 100 protected:
 101 /*! @var eventChainNext
 102         The next event source in the event chain. nil at end of chain. */
 103     IOEventSource *eventChainNext;
 104
 105 /*! @var owner The owner object called when an event has been delivered. */
 106     OSObject *owner;
 107
 108 /*! @var action
 109         The action method called when an event has been delivered */
 110     Action action;
 111
 112 /*! @var enabled
 113         Is this event source enabled to deliver requests to the work-loop. */
 114     bool enabled;
 115
 116 /*! @var workLoop What is the work-loop for this event source. */
 117     IOWorkLoop *workLoop;
 118
 119 /*! @var refcon What ever the client wants to do, see $link setRefcon. */
 120     void *refcon;
 121
 122 /*! @struct ExpansionData
 123     @discussion This structure will be used to expand the capablilties of the IOEventSource in the future.
 124     */
 125     struct ExpansionData { };
 126
 127 /*! @var reserved
 128     Reserved for future use.  (Internal use only)  */
 129     ExpansionData *reserved;
 130
 131 /*! @function init
 132     @abstract Primary initialiser for the IOEventSource class.
 133     @param owner
 134         Owner of this instance of an event source.  Used as the first parameter
 135 of the action callout.  Owner will generally be an OSObject it doesn't have to
 136 be as no member functions will be called directly in it.  It can just be a
 137 refcon for a client routine.
 138     @param action
 139         Pointer to C call out function.  Action is a pointer to a C function
 140 that gets called when this event source has outstanding work.  It will usually
 141 be called by the checkForWork member function.  The first parameter of the
 142 action call out will always be the owner, this allows C++ member functions to
 143 be used as actions.  Defaults to 0.
 144     @result true if the inherited classes and this instance initialise
 145 successfully.
 146 */
 147     virtual bool init(OSObject *owner, IOEventSource::Action action = 0);
 148
 149 /*! @function checkForWork
 150     @abstract Pure Virtual member function used by IOWorkLoop for work
 151 scheduling.
 152     @discussion This function will be called to request a subclass to check
 153 it's internal state for any work to do and then to call out the owner/action.
 154     @result Return true if this function needs to be called again before all its outstanding events have been processed.
 155         */
 156     virtual bool checkForWork() = 0;
 157
 158 /*! @function setWorkLoop
 159     @abstract Set'ter for $link workLoop variable.
 160     @param workLoop
 161         Target work-loop of this event source instance.  A subclass of
 162 IOWorkLoop that at least reacts to signalWorkAvailable() and onThread functions.
 163 */
 164     virtual void setWorkLoop(IOWorkLoop *workLoop);
 165
 166 /*! @function setNext
 167     @abstract Set'ter for $link eventChainNext variable.
 168     @param next
 169         Pointer to another IOEventSource instance.
 170 */
 171     virtual void setNext(IOEventSource *next);
 172
 173 /*! @function getNext
 174     @abstract Get'ter for $link eventChainNext variable.
 175     @result value of eventChainNext.
 176 */
 177     virtual IOEventSource *getNext() const;
 178
 179
 180 protected:
 181     // Methods to access the IOWorkLoop exported fields
 182     /* inline */ void signalWorkAvailable();
 183         /* { workLoop->signalWorkAvailable(); }; */
 184     /* inline */ void openGate();
 185         /* { workLoop->openGate(); }; */
 186     /* inline */ void closeGate();
 187         /* { workLoop->closeGate(); }; */
 188     /* inline */ bool tryCloseGate();
 189         /* { return workLoop->tryCloseGate(); }; */
 190     /* inline */ int sleepGate(void *event, UInt32 type);
 191         /* { return workLoop->sleepGate(event, type); }; */
 192     /* inline */ void wakeupGate(void *event, bool oneThread);
 193         /* { workLoop->wakeupGate(event, oneThread); }; */
 194
 195 public:
 196 /*! @function setAction
 197     @abstract Set'ter for $link action variable.
 198     @param action Pointer to a C function of type IOEventSource::Action. */
 199     virtual void setAction(IOEventSource::Action action);
 200
 201 /*! @function getAction
 202     @abstract Get'ter for $link action variable.
 203     @result value of action. */
 204     virtual IOEventSource::Action getAction() const;
 205
 206 /*! @function enable
 207     @abstract Enable event source.
 208     @discussion A subclass implementation is expected to respect the enabled
 209 state when checkForWork is called.  Calling this function will cause the
 210 work-loop to be signalled so that a checkForWork is performed. */
 211     virtual void enable();
 212
 213 /*! @function disable
 214     @abstract Disable event source.
 215     @discussion A subclass implementation is expected to respect the enabled
 216 state when checkForWork is called. */
 217     virtual void disable();
 218
 219 /*! @function isEnabled
 220     @abstract Get'ter for $link enable variable.
 221     @result true if enabled. */
 222     virtual bool isEnabled() const;
 223
 224 /*! @function getWorkLoop
 225     @abstract Get'ter for $link workLoop variable.
 226     @result value of workLoop. */
 227     virtual IOWorkLoop *getWorkLoop() const;
 228
 229 /*! @function onThread
 230     @abstract Convenience function for workLoop->onThread.
 231     @result true if called on the work-loop thread.
 232 */
 233     virtual bool onThread() const;
 234
 235 private:
 236     OSMetaClassDeclareReservedUnused(IOEventSource, 0);
 237     OSMetaClassDeclareReservedUnused(IOEventSource, 1);
 238     OSMetaClassDeclareReservedUnused(IOEventSource, 2);
 239     OSMetaClassDeclareReservedUnused(IOEventSource, 3);
 240     OSMetaClassDeclareReservedUnused(IOEventSource, 4);
 241     OSMetaClassDeclareReservedUnused(IOEventSource, 5);
 242     OSMetaClassDeclareReservedUnused(IOEventSource, 6);
 243     OSMetaClassDeclareReservedUnused(IOEventSource, 7);
 244 };
 245
 246 #endif /* !_IOKIT_IOEVENTSOURCE_H */