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1.1 root 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: #include <libkern/c++/OSObject.h>
23: #include <IOKit/IOReturn.h>
24:
25: // This is a list of State Changes which are in progress. Its purpose is to keep track of the
26: // notifications and acknowledgements caused by state change. A change is added to the list
27: // when either our parent notifies us that the power domain is changing state or when we decide
28: // to change power to our device or domain.
29: //
30: // A change is removed from the list when all interested parties have been informed of the upcoming
31: // change, all of them have acknowledged the notification, the change has been made, all interested
32: // parties have been informed that the change was made, and all of them have acknowledged.
33: //
34: // The list is strictly first-in, first-out. It is implemented as a circular list in a linear
35: // array. There are two pointers into the array. The circular list is empty when these two
36: // pointers are equal.
37:
38: // More specifically, a change note is put into the array when one of these things happens:
39: // the device decides it is idle and needs to reduce power. (changeStateTo)
40: // the device decides it is not idle and needs to increase power. (changeStateTo)
41: // the controlling driver requests a state change. (changeStateTo)
42: // some client needs to use the device but it is powered down. (makeUsable)
43: // the parent says the domain power is changing. (powerStateWillChangeTo)
44: // a child says it no longer needs power, and all other children are similarly idle. (requestDomainState)
45: //. a child wants more power in the domain so it can raise its power state. (requestDomainState)
46: //
47: // A change note is removed from the array when all interested drivers and power domain
48: // children have acknowledged the change.
49:
50: // Each change note contains:
51: // A flag field which describes the change.
52: // Which power state the device will be in after the change.
53: // The power flags which describe the result of this change.
54:
55: struct changeNoteItem{
56: unsigned long flags;
57: unsigned long newStateNumber;
58: IOPMPowerFlags outputPowerCharacter;
59: IOPMPowerFlags inputPowerRequirement;
60: IOPMPowerFlags domainState;
61: IOPMPowerFlags capabilityFlags;
62: };
63:
64: typedef struct changeNoteItem changeNoteItem;
65:
66:
67: // flags field
68:
69: #define IOPMParentInitiated 1 // this power change initiated by our parent
70: #define IOPMWeInitiated 2 // this power change initiated by this device (not parent)
71: #define IOPMNotDone 4 // we couldn't make this change
72: #define IOPMNotInUse 8 // this list element not currently in use
73:
74:
75: // Length of change note list is maximum 5. There cannot be two adjacent device-initiated change notes unless
76: // one is currently being actioned, because two adjacent in-active device-initiated changes are always collapsed
77: // into one, and there cannot be more than two parent-initiated change notes in the queue, because the parent does not
78: // initiate a change (by calling domainStateWillChange) until everybody has acknowledged the previous one
79: // (by calling domainStateDidChange), although if we are the last to send that acknowledgement, the change we
80: // are acknowledging will still be in the queue as we acknowledge, and at that point the parent can give us another
81: // (by callingdomainStateWillChange). So we need room for two parent changes, two non-adjacent device changes,
82: // and room for one more device change to get into the queue before collapsing it with its neighbor. Or, we need
83: // room for two adjacent device changes (one in progress), a parent change, another device change, and room for
84: // one more device change to get into the queue before collapsing it with its neighbor. Five entries in either case.
85: // I'm not sure what irrationallity causes me to code for ten entries in the queue.
86: #define IOPMMaxChangeNotes 10
87:
88: class IOPMchangeNoteList :public OSObject
89: {
90: OSDeclareDefaultStructors(IOPMchangeNoteList)
91:
92: private:
93: unsigned long firstInList; // points to oldest active change note in list
94: unsigned long firstUnused; // points just beyond newest change note in list
95:
96: public:
97:
98: changeNoteItem changeNote[IOPMMaxChangeNotes];
99:
100:
101: void initialize ( void );
102:
103: long createChangeNote ( void );
104:
105: long currentChange ( void );
106:
107: long latestChange ( void );
108:
109: IOReturn releaseHeadChangeNote ( void );
110:
111: IOReturn releaseTailChangeNote ( void );
112:
113: bool changeNoteInUse ( unsigned long ordinal );
114:
115: long nextChangeNote ( unsigned long ordinal );
116:
117: unsigned long increment (unsigned long ordinal );
118:
119: unsigned long decrement (unsigned long ordinal );
120:
121: long previousChangeNote (unsigned long ordinal );
122:
123: bool listEmpty ( void );
124:
125: };
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