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     {
 137         kPassive         = 0x0001,
 138         kActive          = 0x0002,
 139         kActionBlock     = 0x0004,
 140         kSubClass0       = 0x0008,
 141     };
 142     uint8_t  eventSourceReserved1[1];
 143     uint16_t flags;
 144 #if __LP64__
 145     uint8_t eventSourceReserved2[4];
 146 #endif /* __LP64__ */
 147
 148 #endif /* XNU_KERNEL_PRIVATE */
 149
 150 /*! @var workLoop What is the work-loop for this event source. */
 151     IOWorkLoop *workLoop;
 152
 153 /*! @var refcon What ever the client wants to do, see $link setRefcon. */
 154     void *refcon;
 155
 156 /*! @struct ExpansionData
 157     @discussion This structure will be used to expand the capablilties of the IOEventSource in the future.
 158     */
 159     struct ExpansionData {
 160 #if IOKITSTATS
 161             struct IOEventSourceCounter *counter;
 162 #else
 163             void *iokitstatsReserved;
 164 #endif
 165         };
 166
 167 /*! @var reserved
 168     Reserved for future use.  (Internal use only)  */
 169     ExpansionData *reserved;
 170
 171 /*! @function init
 172     @abstract Primary initialiser for the IOEventSource class.
 173     @param owner
 174         Owner of this instance of an event source.  Used as the first parameter
 175 of the action callout.  Owner must be an OSObject.
 176     @param action
 177         Pointer to C call out function.  Action is a pointer to a C function
 178 that gets called when this event source has outstanding work.  It will usually
 179 be called by the checkForWork member function.  The first parameter of the
 180 action call out will always be the owner, this allows C++ member functions to
 181 be used as actions.  Defaults to 0.
 182     @result true if the inherited classes and this instance initialise
 183 successfully.
 184 */
 185     virtual bool init(OSObject *owner, IOEventSource::Action action = 0);
 186
 187     virtual void free( void ) APPLE_KEXT_OVERRIDE;
 188
 189 /*! @function checkForWork
 190     @abstract Virtual member function used by IOWorkLoop for work
 191 scheduling.
 192     @discussion This function will be called to request a subclass to check
 193 its internal state for any work to do and then to call out the owner/action.
 194 If this event source never performs any work (e.g. IOCommandGate), this
 195 method should not be overridden. NOTE: This method is no longer declared pure
 196 virtual. A default implementation is provided in IOEventSource.
 197     @result Return true if this function needs to be called again before all its outstanding events have been processed.
 198         */
 199     virtual bool checkForWork();
 200
 201 /*! @function setWorkLoop
 202     @abstract Set'ter for $link workLoop variable.
 203     @param workLoop
 204         Target work-loop of this event source instance.  A subclass of
 205 IOWorkLoop that at least reacts to signalWorkAvailable() and onThread functions.
 206 */
 207     virtual void setWorkLoop(IOWorkLoop *workLoop);
 208
 209 /*! @function setNext
 210     @abstract Set'ter for $link eventChainNext variable.
 211     @param next
 212         Pointer to another IOEventSource instance.
 213 */
 214     virtual void setNext(IOEventSource *next);
 215
 216 /*! @function getNext
 217     @abstract Get'ter for $link eventChainNext variable.
 218     @result value of eventChainNext.
 219 */
 220     virtual IOEventSource *getNext() const;
 221
 222
 223 protected:
 224     // Methods to access the IOWorkLoop exported fields
 225     void signalWorkAvailable();
 226     void openGate();
 227     void closeGate();
 228     bool tryCloseGate();
 229     int sleepGate(void *event, UInt32 type);
 230         int sleepGate(void *event, AbsoluteTime deadline, UInt32 type);
 231     void wakeupGate(void *event, bool oneThread);
 232
 233 public:
 234 /*! @function setAction
 235     @abstract Set'ter for $link action variable.
 236     @param action Pointer to a C function of type IOEventSource::Action. */
 237     virtual void setAction(IOEventSource::Action action);
 238
 239 /*! @function getAction
 240     @abstract Get'ter for $link action variable.
 241     @result value of action. */
 242     virtual IOEventSource::Action getAction() const;
 243
 244 #ifdef __BLOCKS__
 245 /*! @function setActionBlock
 246     @abstract Setter for action ivar. The current block is released, & the new block is retained.
 247     @param block Block pointer of type IOEventSource::ActionBlock. */
 248     void setActionBlock(ActionBlock block);
 249 /*! @function getActionBlock
 250     @abstract Getter for action ivar.
 251     @result Block pointer of type IOEventSource::ActionBlock, if set, or NULL. */
 252     ActionBlock getActionBlock(ActionBlock) const;
 253 #endif /* __BLOCKS__ */
 254
 255 /*! @function setRefcon
 256     @abstract Setter for refcon ivar. This function will assert if a block action has been set.
 257     @param refcon Refcon. */
 258     void setRefcon(void *refcon);
 259 /*! @function getRefcon
 260     @abstract Getter for refcon ivar.
 261     @result The refcon. This function will assert if a block action has been set. */
 262     void * getRefcon() const;
 263
 264 /*! @function enable
 265     @abstract Enable event source.
 266     @discussion A subclass implementation is expected to respect the enabled
 267 state when checkForWork is called.  Calling this function will cause the
 268 work-loop to be signalled so that a checkForWork is performed. */
 269     virtual void enable();
 270
 271 /*! @function disable
 272     @abstract Disable event source.
 273     @discussion A subclass implementation is expected to respect the enabled
 274 state when checkForWork is called. */
 275     virtual void disable();
 276
 277 /*! @function isEnabled
 278     @abstract Get'ter for $link enable variable.
 279     @result true if enabled. */
 280     virtual bool isEnabled() const;
 281
 282 /*! @function getWorkLoop
 283     @abstract Get'ter for $link workLoop variable.
 284     @result value of workLoop. */
 285     virtual IOWorkLoop *getWorkLoop() const;
 286
 287 /*! @function onThread
 288     @abstract Convenience function for workLoop->onThread.
 289     @result true if called on the work-loop thread.
 290 */
 291     virtual bool onThread() const;
 292
 293 private:
 294     OSMetaClassDeclareReservedUnused(IOEventSource, 0);
 295     OSMetaClassDeclareReservedUnused(IOEventSource, 1);
 296     OSMetaClassDeclareReservedUnused(IOEventSource, 2);
 297     OSMetaClassDeclareReservedUnused(IOEventSource, 3);
 298     OSMetaClassDeclareReservedUnused(IOEventSource, 4);
 299     OSMetaClassDeclareReservedUnused(IOEventSource, 5);
 300     OSMetaClassDeclareReservedUnused(IOEventSource, 6);
 301     OSMetaClassDeclareReservedUnused(IOEventSource, 7);
 302 };
 303
 304 #endif /* !_IOKIT_IOEVENTSOURCE_H */