1/*
2 * Copyright (c) 1998-2016 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
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27 */
28/*[
29 1999-8-10 Godfrey van der Linden(gvdl)
30 Created.
31]*/
32/*! @language embedded-c++ */
33
34#ifndef _IOKIT_IOCOMMANDGATE_H
35#define _IOKIT_IOCOMMANDGATE_H
36
37#include <IOKit/IOEventSource.h>
38
39/*!
40 @class IOCommandGate : public IOEventSource
41 @abstract Single-threaded work loop client request mechanism.
42 @discussion An IOCommandGate instance is an extremely lightweight mechanism
43that executes an action on the driver's work loop. Although the code does not
44technically execute on the work loop itself, a single-threaded work loop semantic
45is maintained for this event source using the work loop gate. The command gate
46tests for a potential self dead lock by checking if the runCommand request is
47made from the work loop's thread, it doesn't check for a mutual dead lock though
48where a pair of work loop's dead lock each other.
49<br><br>
50 The IOCommandGate is a lighter weight version of the IOCommandQueue and
51should be used in preference. Generally use a command queue whenever you need a
52client to submit a request to a work loop. A typical command gate action would
53check if the hardware is active, if so it will add the request to a pending
54queue internal to the device or the device's family. Otherwise if the hardware
55is inactive then this request can be acted upon immediately.
56<br><br>
57 CAUTION: The runAction, runCommand, and attemptCommand functions cannot be called from an interrupt context.
58
59*/
60class IOCommandGate : public IOEventSource
61{
62 OSDeclareDefaultStructors(IOCommandGate)
63
64public:
65/*!
66 @typedef Action
67 @discussion Type and arguments of callout C function that is used when
68a runCommand is executed by a client. Cast to this type when you want a C++
69member function to be used. Note the arg1 - arg3 parameters are straight pass
70through from the runCommand to the action callout.
71 @param owner
72 Target of the function, can be used as a refcon. The owner is set
73during initialisation of the IOCommandGate instance. Note if a C++ function
74was specified this parameter is implicitly the first paramter in the target
75member function's parameter list.
76 @param arg0 Argument to action from run operation.
77 @param arg1 Argument to action from run operation.
78 @param arg2 Argument to action from run operation.
79 @param arg3 Argument to action from run operation.
80*/
81 typedef IOReturn (*Action)(OSObject *owner,
82 void *arg0, void *arg1,
83 void *arg2, void *arg3);
84
85protected:
86
87/*! @struct ExpansionData
88 @discussion This structure will be used to expand the capablilties of the IOWorkLoop in the future.
89 */
90 struct ExpansionData { };
91
92/*! @var reserved
93 Reserved for future use. (Internal use only) */
94 APPLE_KEXT_WSHADOW_PUSH;
95 ExpansionData *reserved;
96 APPLE_KEXT_WSHADOW_POP;
97
98public:
99/*! @function commandGate
100 @abstract Factory method to create and initialise an IOCommandGate, See $link init.
101 @result Returns a pointer to the new command gate if sucessful, 0 otherwise. */
102 static IOCommandGate *commandGate(OSObject *owner, Action action = 0);
103
104/*! @function init
105 @abstract Class initialiser.
106 @discussion Initialiser for IOCommandGate operates only on newly 'newed'
107objects. Shouldn't be used to re-init an existing instance.
108 @param owner Owner of this, newly created, instance of the IOCommandGate. This argument will be used as the first parameter in the action callout.
109 @param action
110 Pointer to a C function that is called whenever a client of the
111IOCommandGate calls runCommand. NB Can be a C++ member function but caller
112must cast the member function to $link IOCommandGate::Action and they will get a
113compiler warning. Defaults to zero, see $link IOEventSource::setAction.
114 @result True if inherited classes initialise successfully. */
115 virtual bool init(OSObject *owner, Action action = 0);
116
117 // Superclass overrides
118 virtual void free() APPLE_KEXT_OVERRIDE;
119 virtual void setWorkLoop(IOWorkLoop *inWorkLoop) APPLE_KEXT_OVERRIDE;
120
121/*! @function runCommand
122 @abstract Single thread a command with the target work loop.
123 @discussion Client function that causes the current action to be called in
124a single threaded manner. Beware the work loop's gate is recursive and command
125gates can cause direct or indirect re-entrancy. When the executing on a
126client's thread runCommand will sleep until the work loop's gate opens for
127execution of client actions, the action is single threaded against all other
128work loop event sources. If the command is disabled the attempt to run a command will be stalled until enable is called.
129 @param arg0 Parameter for action of command gate, defaults to 0.
130 @param arg1 Parameter for action of command gate, defaults to 0.
131 @param arg2 Parameter for action of command gate, defaults to 0.
132 @param arg3 Parameter for action of command gate, defaults to 0.
133 @result kIOReturnSuccess if successful. kIOReturnAborted if a disabled command gate is free()ed before being reenabled, kIOReturnNoResources if no action available.
134*/
135 virtual IOReturn runCommand(void *arg0 = 0, void *arg1 = 0,
136 void *arg2 = 0, void *arg3 = 0);
137
138/*! @function runAction
139 @abstract Single thread a call to an action with the target work loop.
140 @discussion Client function that causes the given action to be called in
141a single threaded manner. Beware the work loop's gate is recursive and command
142gates can cause direct or indirect re-entrancy. When the executing on a
143client's thread runAction will sleep until the work loop's gate opens for
144execution of client actions, the action is single threaded against all other
145work loop event sources. If the command is disabled the attempt to run a command will be stalled until enable is called.
146 @param action Pointer to function to be executed in the context of the work loop.
147 @param arg0 Parameter for action parameter, defaults to 0.
148 @param arg1 Parameter for action parameter, defaults to 0.
149 @param arg2 Parameter for action parameter, defaults to 0.
150 @param arg3 Parameter for action parameter, defaults to 0.
151 @result The return value of action if it was called, kIOReturnBadArgument if action is not defined, kIOReturnAborted if a disabled command gate is free()ed before being reenabled.
152*/
153 virtual IOReturn runAction(Action action,
154 void *arg0 = 0, void *arg1 = 0,
155 void *arg2 = 0, void *arg3 = 0);
156
157#ifdef __BLOCKS__
158/*! @function runActionBlock
159 @abstract Single thread a call to an action with the target work loop.
160 @discussion Client function that causes the given action to be called in
161a single threaded manner. Beware the work loop's gate is recursive and command
162gates can cause direct or indirect re-entrancy. When the executing on a
163client's thread runAction will sleep until the work loop's gate opens for
164execution of client actions, the action is single threaded against all other
165work loop event sources. If the command is disabled the attempt to run a command will be stalled until enable is called.
166 @param action Block to be executed in the context of the work loop.
167 @result The return value of action if it was called, kIOReturnBadArgument if action is not defined, kIOReturnAborted if a disabled command gate is free()ed before being reenabled.
168*/
169 IOReturn runActionBlock(ActionBlock action);
170#endif /* __BLOCKS__ */
171
172/*! @function attemptCommand
173 @abstract Single thread a command with the target work loop.
174 @discussion Client function that causes the current action to be called in
175a single threaded manner. When the executing on a client's thread attemptCommand will fail if the work loop's gate is closed.
176 @param arg0 Parameter for action of command gate, defaults to 0.
177 @param arg1 Parameter for action of command gate, defaults to 0.
178 @param arg2 Parameter for action of command gate, defaults to 0.
179 @param arg3 Parameter for action of command gate, defaults to 0.
180 @result kIOReturnSuccess if successful. kIOReturnNotPermitted if this event source is currently disabled, kIOReturnNoResources if no action available, kIOReturnCannotLock if lock attempt fails.
181*/
182 virtual IOReturn attemptCommand(void *arg0 = 0, void *arg1 = 0,
183 void *arg2 = 0, void *arg3 = 0);
184
185/*! @function attemptAction
186 @abstract Single thread a call to an action with the target work loop.
187 @discussion Client function that causes the given action to be called in
188a single threaded manner. Beware the work loop's gate is recursive and command
189gates can cause direct or indirect re-entrancy. When the executing on a
190client's thread attemptCommand will fail if the work loop's gate is closed.
191 @param action Pointer to function to be executed in context of the work loop.
192 @param arg0 Parameter for action parameter, defaults to 0.
193 @param arg1 Parameter for action parameter, defaults to 0.
194 @param arg2 Parameter for action parameter, defaults to 0.
195 @param arg3 Parameter for action parameter, defaults to 0.
196 @result kIOReturnSuccess if successful. kIOReturnBadArgument if action is not defined, kIOReturnNotPermitted if this event source is currently disabled, kIOReturnCannotLock if lock attempt fails.
197
198*/
199 virtual IOReturn attemptAction(Action action,
200 void *arg0 = 0, void *arg1 = 0,
201 void *arg2 = 0, void *arg3 = 0);
202
203/*! @function commandSleep
204 @abstract Put a thread that is currently holding the command gate to sleep.
205 @discussion Put a thread to sleep waiting for an event but release the gate first. If the event occurs then the commandGate is closed before the function returns. If the thread does not hold the gate, panic.
206 @param event Pointer to an address.
207 @param interruptible THREAD_UNINT, THREAD_INTERRUPTIBLE or THREAD_ABORTSAFE. THREAD_UNINT specifies that the sleep cannot be interrupted by a signal. THREAD_INTERRUPTIBLE specifies that the sleep may be interrupted by a "kill -9" signal. THREAD_ABORTSAFE (the default value) specifies that the sleep may be interrupted by any user signal.
208 @result THREAD_AWAKENED - normal wakeup, THREAD_TIMED_OUT - timeout expired, THREAD_INTERRUPTED - interrupted, THREAD_RESTART - restart operation entirely. */
209 virtual IOReturn commandSleep(void *event,
210 UInt32 interruptible = THREAD_ABORTSAFE);
211
212/*! @function commandWakeup
213 @abstract Wakeup one or more threads that are asleep on an event.
214 @param event Pointer to an address.
215 @param oneThread true to only wake up at most one thread, false otherwise. */
216 virtual void commandWakeup(void *event, bool oneThread = false);
217
218/*! @function disable
219 @abstract Disable the command gate
220 @discussion When a command gate is disabled all future calls to runAction and runCommand will stall until the gate is enable()d later. This can be used to block client threads when a system sleep is requested. The IOWorkLoop thread itself will never stall, even when making runAction/runCommand calls. This call must be made from a gated context, to clear potential race conditions. */
221 virtual void disable() APPLE_KEXT_OVERRIDE;
222
223/*! @function enable
224 @abstract Enable command gate, this will unblock any blocked Commands and Actions.
225 @discussion Enable the command gate. The attemptAction/attemptCommand calls will now be enabled and can succeeed. Stalled runCommand/runAction calls will be woken up. */
226 virtual void enable() APPLE_KEXT_OVERRIDE;
227
228/*! @function commandSleep
229 @abstract Put a thread that is currently holding the command gate to sleep.
230 @discussion Put a thread to sleep waiting for an event but release the gate first. If the event occurs or timeout occurs then the commandGate is closed before the function returns. If the thread does not hold the gate, panic.
231 @param event Pointer to an address.
232 @param deadline Clock deadline to timeout the sleep.
233 @param interruptible THREAD_UNINT, THREAD_INTERRUPTIBLE or THREAD_ABORTSAFE. THREAD_UNINT specifies that the sleep cannot be interrupted by a signal. THREAD_INTERRUPTIBLE specifies that the sleep may be interrupted by a "kill -9" signal. THREAD_ABORTSAFE specifies that the sleep may be interrupted by any user signal.
234 @result THREAD_AWAKENED - normal wakeup, THREAD_TIMED_OUT - timeout expired, THREAD_INTERRUPTED - interrupted, THREAD_RESTART - restart operation entirely. */
235 virtual IOReturn commandSleep(void *event,
236 AbsoluteTime deadline,
237 UInt32 interruptible);
238
239private:
240#if __LP64__
241 OSMetaClassDeclareReservedUnused(IOCommandGate, 0);
242#else
243 OSMetaClassDeclareReservedUsed(IOCommandGate, 0);
244#endif
245 OSMetaClassDeclareReservedUnused(IOCommandGate, 1);
246 OSMetaClassDeclareReservedUnused(IOCommandGate, 2);
247 OSMetaClassDeclareReservedUnused(IOCommandGate, 3);
248 OSMetaClassDeclareReservedUnused(IOCommandGate, 4);
249 OSMetaClassDeclareReservedUnused(IOCommandGate, 5);
250 OSMetaClassDeclareReservedUnused(IOCommandGate, 6);
251 OSMetaClassDeclareReservedUnused(IOCommandGate, 7);
252};
253
254#endif /* !_IOKIT_IOCOMMANDGATE_H */
255