iokit/IOKit/IOEventSource.h

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29 Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
  30 HISTORY
  31     1998-7-13   Godfrey van der Linden(gvdl)
  32         Created.
  33     1998-10-30  Godfrey van der Linden(gvdl)
  34         Converted to C++
  35 */
  36 #ifndef _IOKIT_IOEVENTSOURCE_H
  37 #define _IOKIT_IOEVENTSOURCE_H
  38
  39 #include <sys/cdefs.h>
  40
  41 #include <libkern/c++/OSObject.h>
  42
  43 #include <IOKit/IOLib.h>
  44 #include <IOKit/system.h>
  45 #include <IOKit/IOWorkLoop.h>
  46
  47
  48 __BEGIN_DECLS
  49 #include <mach/clock_types.h>
  50 #include <kern/clock.h>
  51 __END_DECLS
  52
  53 /*!
  54     @class IOEventSource : public OSObject
  55     @abstract Abstract class for all work-loop event sources.
  56     @discussion The IOEventSource declares the abstract super class that all
  57 event sources must inherit from if an IOWorkLoop is to receive events from them.
  58 <br><br>
  59         An event source can represent any event that should cause the work-loop of a
  60 device to wake up and perform work.  Two examples of event sources are the
  61 IOInterruptEventSource which delivers interrupt notifications and IOCommandGate
  62 which delivers command requests.
  63 <br><br>
  64         A kernel module can always use the work-loop model for serialising access to
  65 anything at all.  The IOEventSource is used for communicating events to the
  66 work-loop, and the chain of event sources should be used to walk the possible
  67 event sources and demultipex them.  Note a particular instance of an event
  68 source may only be a member of 1 linked list chain.  If you need to move it
  69 between chains than make sure it is removed from the original chain before
  70 attempting to move it.
  71 <br><br>
  72         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.
  73 <br><br>
  74         All subclasses of the IOEventSource are expected to implement the checkForWork() member function.
  75
  76 <br><br>
  77         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.
  78 <br><br>
  79         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.
  80 */
  81 class IOEventSource : public OSObject
  82 {
  83     OSDeclareAbstractStructors(IOEventSource)
  84     friend class IOWorkLoop;
  85
  86 public:
  87 /*!
  88     @typedef Action
  89     @discussion Placeholder type for C++ function overloading discrimination.
  90 As the all event sources require an action and it has to be stored somewhere
  91 and be of some type, this is that type.
  92     @param owner
  93         Target of the function, can be used as a refcon.  The owner is set
  94 during initialisation.   Note if a C++ function was specified this parameter
  95 is implicitly the first paramter in the target member function's parameter list.
  96 */
  97     typedef void (*Action)(OSObject *owner, ...);
  98
  99 /*! @defined IOEventSourceAction
 100     @discussion Backward compatibilty define for the old non-class scoped type definition.  See $link IOEventSource::Action */
 101  #define IOEventSourceAction IOEventSource::Action
 102
 103 protected:
 104 /*! @var eventChainNext
 105         The next event source in the event chain. nil at end of chain. */
 106     IOEventSource *eventChainNext;
 107
 108 /*! @var owner The owner object called when an event has been delivered. */
 109     OSObject *owner;
 110
 111 /*! @var action
 112         The action method called when an event has been delivered */
 113     Action action;
 114
 115 /*! @var enabled
 116         Is this event source enabled to deliver requests to the work-loop. */
 117     bool enabled;
 118
 119 /*! @var workLoop What is the work-loop for this event source. */
 120     IOWorkLoop *workLoop;
 121
 122 /*! @var refcon What ever the client wants to do, see $link setRefcon. */
 123     void *refcon;
 124
 125 /*! @struct ExpansionData
 126     @discussion This structure will be used to expand the capablilties of the IOEventSource in the future.
 127     */
 128     struct ExpansionData { };
 129
 130 /*! @var reserved
 131     Reserved for future use.  (Internal use only)  */
 132     ExpansionData *reserved;
 133
 134 /*! @function init
 135     @abstract Primary initialiser for the IOEventSource class.
 136     @param owner
 137         Owner of this instance of an event source.  Used as the first parameter
 138 of the action callout.  Owner will generally be an OSObject it doesn't have to
 139 be as no member functions will be called directly in it.  It can just be a
 140 refcon for a client routine.
 141     @param action
 142         Pointer to C call out function.  Action is a pointer to a C function
 143 that gets called when this event source has outstanding work.  It will usually
 144 be called by the checkForWork member function.  The first parameter of the
 145 action call out will always be the owner, this allows C++ member functions to
 146 be used as actions.  Defaults to 0.
 147     @result true if the inherited classes and this instance initialise
 148 successfully.
 149 */
 150     virtual bool init(OSObject *owner, IOEventSource::Action action = 0);
 151
 152 /*! @function checkForWork
 153     @abstract Pure Virtual member function used by IOWorkLoop for work
 154 scheduling.
 155     @discussion This function will be called to request a subclass to check
 156 it's internal state for any work to do and then to call out the owner/action.
 157     @result Return true if this function needs to be called again before all its outstanding events have been processed.
 158         */
 159     virtual bool checkForWork() = 0;
 160
 161 /*! @function setWorkLoop
 162     @abstract Set'ter for $link workLoop variable.
 163     @param workLoop
 164         Target work-loop of this event source instance.  A subclass of
 165 IOWorkLoop that at least reacts to signalWorkAvailable() and onThread functions.
 166 */
 167     virtual void setWorkLoop(IOWorkLoop *workLoop);
 168
 169 /*! @function setNext
 170     @abstract Set'ter for $link eventChainNext variable.
 171     @param next
 172         Pointer to another IOEventSource instance.
 173 */
 174     virtual void setNext(IOEventSource *next);
 175
 176 /*! @function getNext
 177     @abstract Get'ter for $link eventChainNext variable.
 178     @result value of eventChainNext.
 179 */
 180     virtual IOEventSource *getNext() const;
 181
 182
 183 protected:
 184     // Methods to access the IOWorkLoop exported fields
 185     /* inline */ void signalWorkAvailable();
 186         /* { workLoop->signalWorkAvailable(); }; */
 187     /* inline */ void openGate();
 188         /* { workLoop->openGate(); }; */
 189     /* inline */ void closeGate();
 190         /* { workLoop->closeGate(); }; */
 191     /* inline */ bool tryCloseGate();
 192         /* { return workLoop->tryCloseGate(); }; */
 193     /* inline */ int sleepGate(void *event, UInt32 type);
 194         /* { return workLoop->sleepGate(event, type); }; */
 195     /* inline */ void wakeupGate(void *event, bool oneThread);
 196         /* { workLoop->wakeupGate(event, oneThread); }; */
 197
 198 public:
 199 /*! @function setAction
 200     @abstract Set'ter for $link action variable.
 201     @param action Pointer to a C function of type IOEventSource::Action. */
 202     virtual void setAction(IOEventSource::Action action);
 203
 204 /*! @function getAction
 205     @abstract Get'ter for $link action variable.
 206     @result value of action. */
 207     virtual IOEventSource::Action getAction() const;
 208
 209 /*! @function enable
 210     @abstract Enable event source.
 211     @discussion A subclass implementation is expected to respect the enabled
 212 state when checkForWork is called.  Calling this function will cause the
 213 work-loop to be signalled so that a checkForWork is performed. */
 214     virtual void enable();
 215
 216 /*! @function disable
 217     @abstract Disable event source.
 218     @discussion A subclass implementation is expected to respect the enabled
 219 state when checkForWork is called. */
 220     virtual void disable();
 221
 222 /*! @function isEnabled
 223     @abstract Get'ter for $link enable variable.
 224     @result true if enabled. */
 225     virtual bool isEnabled() const;
 226
 227 /*! @function getWorkLoop
 228     @abstract Get'ter for $link workLoop variable.
 229     @result value of workLoop. */
 230     virtual IOWorkLoop *getWorkLoop() const;
 231
 232 /*! @function onThread
 233     @abstract Convenience function for workLoop->onThread.
 234     @result true if called on the work-loop thread.
 235 */
 236     virtual bool onThread() const;
 237
 238 private:
 239     OSMetaClassDeclareReservedUnused(IOEventSource, 0);
 240     OSMetaClassDeclareReservedUnused(IOEventSource, 1);
 241     OSMetaClassDeclareReservedUnused(IOEventSource, 2);
 242     OSMetaClassDeclareReservedUnused(IOEventSource, 3);
 243     OSMetaClassDeclareReservedUnused(IOEventSource, 4);
 244     OSMetaClassDeclareReservedUnused(IOEventSource, 5);
 245     OSMetaClassDeclareReservedUnused(IOEventSource, 6);
 246     OSMetaClassDeclareReservedUnused(IOEventSource, 7);
 247 };
 248
 249 #endif /* !_IOKIT_IOEVENTSOURCE_H */