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 247