Merge remote-tracking branch 'remotes/alistair23/tags/pull-riscv-to-apply-20210921...
[qemu.git] / include / hw / resettable.h
1 /*
2 * Resettable interface header.
3 *
4 * Copyright (c) 2019 GreenSocs SAS
5 *
6 * Authors:
7 * Damien Hedde
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
10 * See the COPYING file in the top-level directory.
11 */
12
13 #ifndef HW_RESETTABLE_H
14 #define HW_RESETTABLE_H
15
16 #include "qom/object.h"
17
18 #define TYPE_RESETTABLE_INTERFACE "resettable"
19
20 typedef struct ResettableClass ResettableClass;
21 DECLARE_CLASS_CHECKERS(ResettableClass, RESETTABLE,
22 TYPE_RESETTABLE_INTERFACE)
23
24
25 typedef struct ResettableState ResettableState;
26
27 /**
28 * ResetType:
29 * Types of reset.
30 *
31 * + Cold: reset resulting from a power cycle of the object.
32 *
33 * TODO: Support has to be added to handle more types. In particular,
34 * ResettableState structure needs to be expanded.
35 */
36 typedef enum ResetType {
37 RESET_TYPE_COLD,
38 } ResetType;
39
40 /*
41 * ResettableClass:
42 * Interface for resettable objects.
43 *
44 * See docs/devel/reset.rst for more detailed information about how QEMU models
45 * reset. This whole API must only be used when holding the iothread mutex.
46 *
47 * All objects which can be reset must implement this interface;
48 * it is usually provided by a base class such as DeviceClass or BusClass.
49 * Every Resettable object must maintain some state tracking the
50 * progress of a reset operation by providing a ResettableState structure.
51 * The functions defined in this module take care of updating the
52 * state of the reset.
53 * The base class implementation of the interface provides this
54 * state and implements the associated method: get_state.
55 *
56 * Concrete object implementations (typically specific devices
57 * such as a UART model) should provide the functions
58 * for the phases.enter, phases.hold and phases.exit methods, which
59 * they can set in their class init function, either directly or
60 * by calling resettable_class_set_parent_phases().
61 * The phase methods are guaranteed to only only ever be called once
62 * for any reset event, in the order 'enter', 'hold', 'exit'.
63 * An object will always move quickly from 'enter' to 'hold'
64 * but might remain in 'hold' for an arbitrary period of time
65 * before eventually reset is deasserted and the 'exit' phase is called.
66 * Object implementations should be prepared for functions handling
67 * inbound connections from other devices (such as qemu_irq handler
68 * functions) to be called at any point during reset after their
69 * 'enter' method has been called.
70 *
71 * Users of a resettable object should not call these methods
72 * directly, but instead use the function resettable_reset().
73 *
74 * @phases.enter: This phase is called when the object enters reset. It
75 * should reset local state of the object, but it must not do anything that
76 * has a side-effect on other objects, such as raising or lowering a qemu_irq
77 * line or reading or writing guest memory. It takes the reset's type as
78 * argument.
79 *
80 * @phases.hold: This phase is called for entry into reset, once every object
81 * in the system which is being reset has had its @phases.enter method called.
82 * At this point devices can do actions that affect other objects.
83 *
84 * @phases.exit: This phase is called when the object leaves the reset state.
85 * Actions affecting other objects are permitted.
86 *
87 * @get_state: Mandatory method which must return a pointer to a
88 * ResettableState.
89 *
90 * @get_transitional_function: transitional method to handle Resettable objects
91 * not yet fully moved to this interface. It will be removed as soon as it is
92 * not needed anymore. This method is optional and may return a pointer to a
93 * function to be used instead of the phases. If the method exists and returns
94 * a non-NULL function pointer then that function is executed as a replacement
95 * of the 'hold' phase method taking the object as argument. The two other phase
96 * methods are not executed.
97 *
98 * @child_foreach: Executes a given callback on every Resettable child. Child
99 * in this context means a child in the qbus tree, so the children of a qbus
100 * are the devices on it, and the children of a device are all the buses it
101 * owns. This is not the same as the QOM object hierarchy. The function takes
102 * additional opaque and ResetType arguments which must be passed unmodified to
103 * the callback.
104 */
105 typedef void (*ResettableEnterPhase)(Object *obj, ResetType type);
106 typedef void (*ResettableHoldPhase)(Object *obj);
107 typedef void (*ResettableExitPhase)(Object *obj);
108 typedef ResettableState * (*ResettableGetState)(Object *obj);
109 typedef void (*ResettableTrFunction)(Object *obj);
110 typedef ResettableTrFunction (*ResettableGetTrFunction)(Object *obj);
111 typedef void (*ResettableChildCallback)(Object *, void *opaque,
112 ResetType type);
113 typedef void (*ResettableChildForeach)(Object *obj,
114 ResettableChildCallback cb,
115 void *opaque, ResetType type);
116 typedef struct ResettablePhases {
117 ResettableEnterPhase enter;
118 ResettableHoldPhase hold;
119 ResettableExitPhase exit;
120 } ResettablePhases;
121 struct ResettableClass {
122 InterfaceClass parent_class;
123
124 /* Phase methods */
125 ResettablePhases phases;
126
127 /* State access method */
128 ResettableGetState get_state;
129
130 /* Transitional method for legacy reset compatibility */
131 ResettableGetTrFunction get_transitional_function;
132
133 /* Hierarchy handling method */
134 ResettableChildForeach child_foreach;
135 };
136
137 /**
138 * ResettableState:
139 * Structure holding reset related state. The fields should not be accessed
140 * directly; the definition is here to allow further inclusion into other
141 * objects.
142 *
143 * @count: Number of reset level the object is into. It is incremented when
144 * the reset operation starts and decremented when it finishes.
145 * @hold_phase_pending: flag which indicates that we need to invoke the 'hold'
146 * phase handler for this object.
147 * @exit_phase_in_progress: true if we are currently in the exit phase
148 */
149 struct ResettableState {
150 unsigned count;
151 bool hold_phase_pending;
152 bool exit_phase_in_progress;
153 };
154
155 /**
156 * resettable_state_clear:
157 * Clear the state. It puts the state to the initial (zeroed) state required
158 * to reuse an object. Typically used in realize step of base classes
159 * implementing the interface.
160 */
161 static inline void resettable_state_clear(ResettableState *state)
162 {
163 memset(state, 0, sizeof(ResettableState));
164 }
165
166 /**
167 * resettable_reset:
168 * Trigger a reset on an object @obj of type @type. @obj must implement
169 * Resettable interface.
170 *
171 * Calling this function is equivalent to calling @resettable_assert_reset()
172 * then @resettable_release_reset().
173 */
174 void resettable_reset(Object *obj, ResetType type);
175
176 /**
177 * resettable_assert_reset:
178 * Put an object @obj into reset. @obj must implement Resettable interface.
179 *
180 * @resettable_release_reset() must eventually be called after this call.
181 * There must be one call to @resettable_release_reset() per call of
182 * @resettable_assert_reset(), with the same type argument.
183 *
184 * NOTE: Until support for migration is added, the @resettable_release_reset()
185 * must not be delayed. It must occur just after @resettable_assert_reset() so
186 * that migration cannot be triggered in between. Prefer using
187 * @resettable_reset() for now.
188 */
189 void resettable_assert_reset(Object *obj, ResetType type);
190
191 /**
192 * resettable_release_reset:
193 * Release the object @obj from reset. @obj must implement Resettable interface.
194 *
195 * See @resettable_assert_reset() description for details.
196 */
197 void resettable_release_reset(Object *obj, ResetType type);
198
199 /**
200 * resettable_is_in_reset:
201 * Return true if @obj is under reset.
202 *
203 * @obj must implement Resettable interface.
204 */
205 bool resettable_is_in_reset(Object *obj);
206
207 /**
208 * resettable_change_parent:
209 * Indicate that the parent of Ressettable @obj is changing from @oldp to @newp.
210 * All 3 objects must implement resettable interface. @oldp or @newp may be
211 * NULL.
212 *
213 * This function will adapt the reset state of @obj so that it is coherent
214 * with the reset state of @newp. It may trigger @resettable_assert_reset()
215 * or @resettable_release_reset(). It will do such things only if the reset
216 * state of @newp and @oldp are different.
217 *
218 * When using this function during reset, it must only be called during
219 * a hold phase method. Calling this during enter or exit phase is an error.
220 */
221 void resettable_change_parent(Object *obj, Object *newp, Object *oldp);
222
223 /**
224 * resettable_cold_reset_fn:
225 * Helper to call resettable_reset((Object *) opaque, RESET_TYPE_COLD).
226 *
227 * This function is typically useful to register a reset handler with
228 * qemu_register_reset.
229 */
230 void resettable_cold_reset_fn(void *opaque);
231
232 /**
233 * resettable_class_set_parent_phases:
234 *
235 * Save @rc current reset phases into @parent_phases and override @rc phases
236 * by the given new methods (@enter, @hold and @exit).
237 * Each phase is overridden only if the new one is not NULL allowing to
238 * override a subset of phases.
239 */
240 void resettable_class_set_parent_phases(ResettableClass *rc,
241 ResettableEnterPhase enter,
242 ResettableHoldPhase hold,
243 ResettableExitPhase exit,
244 ResettablePhases *parent_phases);
245
246 #endif