iokit/IOKit/IOEventSource.h

   1 /*
   2  * Copyright (c) 1998-2000, 2009 Apple 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,
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  23  * Please see the License for the specific language governing rights and
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  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 #if IOKITSTATS
  48 #include <IOKit/IOStatisticsPrivate.h>
  49 #endif
  50
  51 __BEGIN_DECLS
  52 #include <mach/clock_types.h>
  53 #include <kern/clock.h>
  54 __END_DECLS
  55
  56 /*!
  57  *   @class IOEventSource : public OSObject
  58  *   @abstract Abstract class for all work-loop event sources.
  59  *   @discussion The IOEventSource declares the abstract super class that all
  60  *  event sources must inherit from if an IOWorkLoop is to receive events from them.
  61  *  <br><br>
  62  *       An event source can represent any event that should cause the work-loop of a
  63  *  device to wake up and perform work.  Two examples of event sources are the
  64  *  IOInterruptEventSource which delivers interrupt notifications and IOCommandGate
  65  *  which delivers command requests.
  66  *  <br><br>
  67  *       A kernel module can always use the work-loop model for serialising access to
  68  *  anything at all.  The IOEventSource is used for communicating events to the
  69  *  work-loop, and the chain of event sources should be used to walk the possible
  70  *  event sources and demultipex them.  Note a particular instance of an event
  71  *  source may only be a member of 1 linked list chain.  If you need to move it
  72  *  between chains than make sure it is removed from the original chain before
  73  *  attempting to move it.
  74  *  <br><br>
  75  *       The IOEventSource makes no attempt to maintain the consistency of its 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 using an IOCommandGate and thus single threading access to its state.
  76  *  <br><br>
  77  *       All subclasses of IOEventSource that wish to perform work on the work-loop thread are expected to implement the checkForWork() member function. As of Mac OS X, 10.7 (Darwin 11), checkForWork is no longer pure virtual, and should not be overridden if there is no work to be done.
  78  *
  79  *  <br><br>
  80  *       checkForWork() is the key method in this class.         It is called by some work-loop when convienient and is expected to evaluate its 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.
  81  *  <br><br>
  82  *       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.
  83  */
  84 class IOEventSource : public OSObject
  85 {
  86         OSDeclareAbstractStructors(IOEventSource)
  87         friend class IOWorkLoop;
  88 #if IOKITSTATS
  89         friend class IOStatistics;
  90 #endif
  91
  92 public:
  93 /*!
  94  *   @typedef Action
  95  *   @discussion Placeholder type for C++ function overloading discrimination.
  96  *  As the all event sources require an action and it has to be stored somewhere
  97  *  and be of some type, this is that type.
  98  *   @param owner
  99  *       Target of the function, can be used as a refcon.  The owner is set
 100  *  during initialisation.       Note if a C++ function was specified this parameter
 101  *  is implicitly the first paramter in the target member function's parameter list.
 102  */
 103         typedef void (*Action)(OSObject *owner, ...);
 104
 105 /*! @defined IOEventSourceAction
 106  *   @discussion Backward compatibilty define for the old non-class scoped type definition.  See $link IOEventSource::Action */
 107  #define IOEventSourceAction IOEventSource::Action
 108
 109 #ifdef __BLOCKS__
 110         typedef IOReturn (^ActionBlock)();
 111 #endif /* __BLOCKS__ */
 112
 113 protected:
 114 /*! @var eventChainNext
 115  *       The next event source in the event chain. nil at end of chain. */
 116         IOEventSource *eventChainNext;
 117
 118 /*! @var owner The owner object called when an event has been delivered. */
 119         OSObject *owner;
 120
 121 /*! @var action
 122  *       The action method called when an event has been delivered */
 123
 124 #if XNU_KERNEL_PRIVATE
 125         union { Action action; ActionBlock actionBlock; };
 126 #else /* XNU_KERNEL_PRIVATE */
 127         Action action;
 128 #endif /* !XNU_KERNEL_PRIVATE */
 129
 130 /*! @var enabled
 131  *       Is this event source enabled to deliver requests to the work-loop. */
 132         bool enabled;
 133
 134 #if XNU_KERNEL_PRIVATE
 135         enum{
 136                 kPassive         = 0x0001,
 137                 kActive          = 0x0002,
 138                 kActionBlock     = 0x0004,
 139                 kSubClass0       = 0x0008,
 140         };
 141         uint8_t  eventSourceReserved1[1];
 142         uint16_t flags;
 143 #if __LP64__
 144         uint8_t eventSourceReserved2[4];
 145 #endif /* __LP64__ */
 146
 147 #endif /* XNU_KERNEL_PRIVATE */
 148
 149 /*! @var workLoop What is the work-loop for this event source. */
 150         IOWorkLoop *workLoop;
 151
 152 /*! @var refcon What ever the client wants to do, see $link setRefcon. */
 153         void *refcon;
 154
 155 /*! @struct ExpansionData
 156  *   @discussion This structure will be used to expand the capablilties of the IOEventSource in the future.
 157  */
 158         struct ExpansionData {
 159 #if IOKITSTATS
 160                 struct IOEventSourceCounter *counter;
 161 #else
 162                 void *iokitstatsReserved;
 163 #endif
 164         };
 165
 166 /*! @var reserved
 167  *   Reserved for future use.  (Internal use only)  */
 168         ExpansionData *reserved;
 169
 170 /*! @function init
 171  *   @abstract Primary initialiser for the IOEventSource class.
 172  *   @param owner
 173  *       Owner of this instance of an event source.  Used as the first parameter
 174  *  of the action callout.      Owner must be an OSObject.
 175  *   @param action
 176  *       Pointer to C call out function.         Action is a pointer to a C function
 177  *  that gets called when this event source has outstanding work.  It will usually
 178  *  be called by the checkForWork member function.      The first parameter of the
 179  *  action call out will always be the owner, this allows C++ member functions to
 180  *  be used as actions.  Defaults to 0.
 181  *   @result true if the inherited classes and this instance initialise
 182  *  successfully.
 183  */
 184         virtual bool init(OSObject *owner, IOEventSource::Action action = 0);
 185
 186         virtual void free( void ) APPLE_KEXT_OVERRIDE;
 187
 188 /*! @function checkForWork
 189  *   @abstract Virtual member function used by IOWorkLoop for work
 190  *  scheduling.
 191  *   @discussion This function will be called to request a subclass to check
 192  *  its internal state for any work to do and then to call out the owner/action.
 193  *  If this event source never performs any work (e.g. IOCommandGate), this
 194  *  method should not be overridden. NOTE: This method is no longer declared pure
 195  *  virtual. A default implementation is provided in IOEventSource.
 196  *   @result Return true if this function needs to be called again before all its outstanding events have been processed.
 197  */
 198         virtual bool checkForWork();
 199
 200 /*! @function setWorkLoop
 201  *   @abstract Set'ter for $link workLoop variable.
 202  *   @param workLoop
 203  *       Target work-loop of this event source instance.         A subclass of
 204  *  IOWorkLoop that at least reacts to signalWorkAvailable() and onThread functions.
 205  */
 206         virtual void setWorkLoop(IOWorkLoop *workLoop);
 207
 208 /*! @function setNext
 209  *   @abstract Set'ter for $link eventChainNext variable.
 210  *   @param next
 211  *       Pointer to another IOEventSource instance.
 212  */
 213         virtual void setNext(IOEventSource *next);
 214
 215 /*! @function getNext
 216  *   @abstract Get'ter for $link eventChainNext variable.
 217  *   @result value of eventChainNext.
 218  */
 219         virtual IOEventSource *getNext() const;
 220
 221
 222 protected:
 223 // Methods to access the IOWorkLoop exported fields
 224         void signalWorkAvailable();
 225         void openGate();
 226         void closeGate();
 227         bool tryCloseGate();
 228         int sleepGate(void *event, UInt32 type);
 229         int sleepGate(void *event, AbsoluteTime deadline, UInt32 type);
 230         void wakeupGate(void *event, bool oneThread);
 231
 232 public:
 233 /*! @function setAction
 234  *   @abstract Set'ter for $link action variable.
 235  *   @param action Pointer to a C function of type IOEventSource::Action. */
 236         virtual void setAction(IOEventSource::Action action);
 237
 238 /*! @function getAction
 239  *   @abstract Get'ter for $link action variable.
 240  *   @result value of action. */
 241         virtual IOEventSource::Action getAction() const;
 242
 243 #ifdef __BLOCKS__
 244 /*! @function setActionBlock
 245  *   @abstract Setter for action ivar. The current block is released, & the new block is retained.
 246  *   @param block Block pointer of type IOEventSource::ActionBlock. */
 247         void setActionBlock(ActionBlock block);
 248 /*! @function getActionBlock
 249  *   @abstract Getter for action ivar.
 250  *   @result Block pointer of type IOEventSource::ActionBlock, if set, or NULL. */
 251         ActionBlock getActionBlock(ActionBlock) const;
 252 #endif /* __BLOCKS__ */
 253
 254 /*! @function setRefcon
 255  *   @abstract Setter for refcon ivar. This function will assert if a block action has been set.
 256  *   @param refcon Refcon. */
 257         void setRefcon(void *refcon);
 258 /*! @function getRefcon
 259  *   @abstract Getter for refcon ivar.
 260  *   @result The refcon. This function will assert if a block action has been set. */
 261         void * getRefcon() const;
 262
 263 /*! @function enable
 264  *   @abstract Enable event source.
 265  *   @discussion A subclass implementation is expected to respect the enabled
 266  *  state when checkForWork is called.  Calling this function will cause the
 267  *  work-loop to be signalled so that a checkForWork is performed. */
 268         virtual void enable();
 269
 270 /*! @function disable
 271  *   @abstract Disable event source.
 272  *   @discussion A subclass implementation is expected to respect the enabled
 273  *  state when checkForWork is called. */
 274         virtual void disable();
 275
 276 /*! @function isEnabled
 277  *   @abstract Get'ter for $link enable variable.
 278  *   @result true if enabled. */
 279         virtual bool isEnabled() const;
 280
 281 /*! @function getWorkLoop
 282  *   @abstract Get'ter for $link workLoop variable.
 283  *   @result value of workLoop. */
 284         virtual IOWorkLoop *getWorkLoop() const;
 285
 286 /*! @function onThread
 287  *   @abstract Convenience function for workLoop->onThread.
 288  *   @result true if called on the work-loop thread.
 289  */
 290         virtual bool onThread() const;
 291
 292 private:
 293         OSMetaClassDeclareReservedUnused(IOEventSource, 0);
 294         OSMetaClassDeclareReservedUnused(IOEventSource, 1);
 295         OSMetaClassDeclareReservedUnused(IOEventSource, 2);
 296         OSMetaClassDeclareReservedUnused(IOEventSource, 3);
 297         OSMetaClassDeclareReservedUnused(IOEventSource, 4);
 298         OSMetaClassDeclareReservedUnused(IOEventSource, 5);
 299         OSMetaClassDeclareReservedUnused(IOEventSource, 6);
 300         OSMetaClassDeclareReservedUnused(IOEventSource, 7);
 301 };
 302
 303 #endif /* !_IOKIT_IOEVENTSOURCE_H */