iokit/IOKit/IOTimerEventSource.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) 1999 Apple Computer, Inc.  All rights reserved.
  24  *
  25  * IOTimerEventSource.h
  26  *
  27  * HISTORY
  28  * 2-Feb-1999           Joe Liu (jliu) created.
  29  *
  30  */
  31
  32 #ifndef _IOTIMEREVENTSOURCE
  33 #define _IOTIMEREVENTSOURCE
  34
  35 #include <sys/cdefs.h>
  36
  37 __BEGIN_DECLS
  38 #include <kern/clock.h>
  39 __END_DECLS
  40
  41 #include <IOKit/IOEventSource.h>
  42 #include <IOKit/IOTypes.h>
  43
  44 /*!
  45     @class IOTimerEventSource : public IOEventSource
  46     @abstract Time based event source mechanism.
  47     @discussion An event source that implements a simple timer.  A timeout handler is called once the timeout period expires.  This timeout handler will be called by the work-loop that this event source is attached to.
  48 <br><br>
  49         Usually a timer event source will be used to implement a timeout.  In general when a driver makes a request it will need to setup a call to keep track of when the I/O doesn't complete.  This class is designed to make that somewhat easier.
  50 <br><br>
  51         Remember the system doesn't guarantee the accuracy of the callout.      It is possible that a higher priority thread is running which will delay the execution of the action routine.  In fact the thread will be made runable at the exact requested time, within the accuracy of the CPU's decrementer based interrupt, but the scheduler will then control execution.
  52 */
  53 class IOTimerEventSource : public IOEventSource
  54 {
  55     OSDeclareDefaultStructors(IOTimerEventSource)
  56
  57 protected:
  58 /*! @var calloutEntry thread_call entry for preregistered thread callouts */
  59     void *calloutEntry;
  60
  61 /*! @var abstime time to wake up next, see enable. */
  62     AbsoluteTime abstime;
  63
  64 /*! @struct ExpansionData
  65     @discussion This structure will be used to expand the capablilties of the IOWorkLoop in the future.
  66     */
  67     struct ExpansionData { };
  68
  69 /*! @var reserved
  70     Reserved for future use.  (Internal use only)  */
  71     ExpansionData *reserved;
  72
  73 /*! @function timeout
  74     @abstract Function that routes the call from the OS' timeout mechanism into a work-loop context.
  75     @discussion timeout will normally not be called nor overridden by a subclass.  If the event source is enabled then close the work-loop's gate and call the action routine.
  76     @param self This argument will be cast to an IOTimerEventSource. */
  77     static void timeout(void *self);
  78
  79 /*! @function setTimeoutFunc
  80     @abstract Set's timeout as the function of calloutEntry.
  81     @discussion IOTimerEventSource is based upon the kern/thread_call.h APIs currently.  This function allocates the calloutEntry member variable by using thread_call_allocate(timeout, this).  If you need to write your own subclass of IOTimerEventSource you probably should override this method to allocate an entry that points to your own timeout routine. */
  82     virtual void setTimeoutFunc();
  83
  84 /*! @function free
  85     @abstract Sub-class implementation of free method, frees calloutEntry */
  86     virtual void free();
  87
  88 /*! @function checkForWork
  89     @abstract Have to implement it is mandatory in $link IOEventSource, but IOTimerEventSources don't actually use this work-loop mechanism. */
  90     virtual bool checkForWork();
  91
  92 public:
  93
  94 /*! @typedef Action
  95     @discussion 'C' Function pointer defining the callout routine of this event source.
  96     @param owner Owning target object.  Note by a startling coincidence the first parameter in a C callout is currently used to define the target of a C++ member function.
  97     @param sender The object that timed out. */
  98     typedef void (*Action)(OSObject *owner, IOTimerEventSource *sender);
  99
 100 /*! @function timerEventSource
 101     @abstract Allocates and returns an initialized timer instance.
 102     @param owner
 103     @param action */
 104     static IOTimerEventSource *
 105         timerEventSource(OSObject *owner, Action action = 0);
 106
 107 /*! @function init
 108     @abstract Initializes the timer with an owner, and a handler to call when the timeout expires.
 109     @param owner
 110     @param action */
 111     virtual bool init(OSObject *owner, Action action = 0);
 112
 113 /*! @function enable
 114     @abstract Enables a call to the action.
 115     @discussion Allows the action function to be called.  If the timer event source was disabled while a call was outstanding and the call wasn't cancelled then it will be rescheduled.  So a disable/enable pair will disable calls from this event source. */
 116     virtual void enable();
 117
 118 /*! @function disable
 119     @abstract Disable a timed callout.
 120     @discussion When disable returns the action will not be called until the next time enable(qv) is called. */
 121     virtual void disable();
 122
 123
 124 /*! @function setTimeoutTicks
 125     @abstract Setup a callback at after the delay in scheduler ticks.  See wakeAtTime(AbsoluteTime).
 126     @param interval Delay from now to wake up, in scheduler ticks, whatever that may be.
 127     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 128     virtual IOReturn setTimeoutTicks(UInt32 ticks);
 129
 130 /*! @function setTimeoutMS
 131     @abstract Setup a callback at after the delay in milliseconds.  See wakeAtTime(AbsoluteTime).
 132     @param interval Delay from now to wake up, time in milliseconds.
 133     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 134     virtual IOReturn setTimeoutMS(UInt32 ms);
 135
 136 /*! @function setTimeoutUS
 137         @abstract Setup a callback at after the delay in microseconds.   See wakeAtTime(AbsoluteTime).
 138     @param interval Delay from now to wake up, time in microseconds.
 139     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 140     virtual IOReturn setTimeoutUS(UInt32 us);
 141
 142 /*! @function setTimeout
 143     @abstract Setup a callback at after the delay in some unit.  See wakeAtTime(AbsoluteTime).
 144     @param interval Delay from now to wake up in some defined unit.
 145     @param scale_factor Define the unit of interval, default to nanoseconds.
 146     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 147     virtual IOReturn setTimeout(UInt32 interval,
 148                                 UInt32 scale_factor = kNanosecondScale);
 149
 150 /*! @function setTimeout
 151     @abstract Setup a callback at after the delay in decrementer ticks.  See wakeAtTime(AbsoluteTime).
 152     @param interval Delay from now to wake up.
 153     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 154     virtual IOReturn setTimeout(mach_timespec_t interval);
 155
 156 /*! @function setTimeout
 157     @abstract Setup a callback at after the delay in decrementer ticks.  See wakeAtTime(AbsoluteTime).
 158     @param interval Delay from now to wake up in decrementer ticks.
 159     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 160     virtual IOReturn setTimeout(AbsoluteTime interval);
 161
 162 /*! @function wakeAtTimeTicks
 163     @abstract Setup a callback at this absolute time.  See wakeAtTime(AbsoluteTime).
 164     @param abstime Time to wake up in scheduler quantums, whatever that is?
 165     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 166     virtual IOReturn wakeAtTimeTicks(UInt32 ticks);
 167
 168 /*! @function wakeAtTimeMS
 169     @abstract Setup a callback at this absolute time.  See wakeAtTime(AbsoluteTime).
 170     @param abstime Time to wake up in milliseconds.
 171     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 172     virtual IOReturn wakeAtTimeMS(UInt32 ms);
 173
 174 /*! @function wakeAtTimeUS
 175     @abstract Setup a callback at this absolute time.  See wakeAtTime(AbsoluteTime).
 176     @param abstime Time to wake up in microseconds.
 177     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 178     virtual IOReturn wakeAtTimeUS(UInt32 us);
 179
 180 /*! @function wakeAtTime
 181     @abstract Setup a callback at this absolute time.  See wakeAtTime(AbsoluteTime).
 182     @param abstime Time to wake up in some unit.
 183     @param scale_factor Define the unit of abstime, default to nanoseconds.
 184     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 185     virtual IOReturn wakeAtTime(UInt32 abstime,
 186                                 UInt32 scale_factor = kNanosecondScale);
 187
 188 /*! @function wakeAtTime
 189     @abstract Setup a callback at this absolute time.  See wakeAtTime(AbsoluteTime).
 190     @param abstime mach_timespec_t of the desired callout time.
 191     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared. */
 192     virtual IOReturn wakeAtTime(mach_timespec_t abstime);
 193
 194 /*! @function wakeAtTime
 195     @abstract Setup a callback at this absolute time.
 196     @discussion Starts the timer, which will expire at abstime. After it expires, the timer will call the 'action' registered in the init() function. This timer is not periodic, a further call is needed to reset and restart the timer after it expires.
 197     @param abstime Absolute Time when to wake up, counted in 'decrementer' units and starts at zero when system boots.
 198     @result kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared by init or IOEventSource::setAction (qqv). */
 199     virtual IOReturn wakeAtTime(AbsoluteTime abstime);
 200
 201 /*! @function cancelTimeout
 202     @abstract Disable any outstanding calls to this event source.
 203     @discussion Clear down any oustanding calls.  By the time this function completes it is guaranteed that the action will not be called again. */
 204    virtual void cancelTimeout();
 205
 206 private:
 207     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 0);
 208     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 1);
 209     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 2);
 210     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 3);
 211     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 4);
 212     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 5);
 213     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 6);
 214     OSMetaClassDeclareReservedUnused(IOTimerEventSource, 7);
 215 };
 216
 217 #endif /* !_IOTIMEREVENTSOURCE */