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 #define RESETTABLE_CLASS(class) \ 21 OBJECT_CLASS_CHECK(ResettableClass, (class), TYPE_RESETTABLE_INTERFACE) 22 23 #define RESETTABLE_GET_CLASS(obj) \ 24 OBJECT_GET_CLASS(ResettableClass, (obj), TYPE_RESETTABLE_INTERFACE) 25 26 typedef struct ResettableState ResettableState; 27 28 /** 29 * ResetType: 30 * Types of reset. 31 * 32 * + Cold: reset resulting from a power cycle of the object. 33 * 34 * TODO: Support has to be added to handle more types. In particular, 35 * ResettableState structure needs to be expanded. 36 */ 37 typedef enum ResetType { 38 RESET_TYPE_COLD, 39 } ResetType; 40 41 /* 42 * ResettableClass: 43 * Interface for resettable objects. 44 * 45 * See docs/devel/reset.rst for more detailed information about how QEMU models 46 * reset. This whole API must only be used when holding the iothread mutex. 47 * 48 * All objects which can be reset must implement this interface; 49 * it is usually provided by a base class such as DeviceClass or BusClass. 50 * Every Resettable object must maintain some state tracking the 51 * progress of a reset operation by providing a ResettableState structure. 52 * The functions defined in this module take care of updating the 53 * state of the reset. 54 * The base class implementation of the interface provides this 55 * state and implements the associated method: get_state. 56 * 57 * Concrete object implementations (typically specific devices 58 * such as a UART model) should provide the functions 59 * for the phases.enter, phases.hold and phases.exit methods, which 60 * they can set in their class init function, either directly or 61 * by calling resettable_class_set_parent_phases(). 62 * The phase methods are guaranteed to only only ever be called once 63 * for any reset event, in the order 'enter', 'hold', 'exit'. 64 * An object will always move quickly from 'enter' to 'hold' 65 * but might remain in 'hold' for an arbitrary period of time 66 * before eventually reset is deasserted and the 'exit' phase is called. 67 * Object implementations should be prepared for functions handling 68 * inbound connections from other devices (such as qemu_irq handler 69 * functions) to be called at any point during reset after their 70 * 'enter' method has been called. 71 * 72 * Users of a resettable object should not call these methods 73 * directly, but instead use the function resettable_reset(). 74 * 75 * @phases.enter: This phase is called when the object enters reset. It 76 * should reset local state of the object, but it must not do anything that 77 * has a side-effect on other objects, such as raising or lowering a qemu_irq 78 * line or reading or writing guest memory. It takes the reset's type as 79 * argument. 80 * 81 * @phases.hold: This phase is called for entry into reset, once every object 82 * in the system which is being reset has had its @phases.enter method called. 83 * At this point devices can do actions that affect other objects. 84 * 85 * @phases.exit: This phase is called when the object leaves the reset state. 86 * Actions affecting other objects are permitted. 87 * 88 * @get_state: Mandatory method which must return a pointer to a 89 * ResettableState. 90 * 91 * @get_transitional_function: transitional method to handle Resettable objects 92 * not yet fully moved to this interface. It will be removed as soon as it is 93 * not needed anymore. This method is optional and may return a pointer to a 94 * function to be used instead of the phases. If the method exists and returns 95 * a non-NULL function pointer then that function is executed as a replacement 96 * of the 'hold' phase method taking the object as argument. The two other phase 97 * methods are not executed. 98 * 99 * @child_foreach: Executes a given callback on every Resettable child. Child 100 * in this context means a child in the qbus tree, so the children of a qbus 101 * are the devices on it, and the children of a device are all the buses it 102 * owns. This is not the same as the QOM object hierarchy. The function takes 103 * additional opaque and ResetType arguments which must be passed unmodified to 104 * the callback. 105 */ 106 typedef void (*ResettableEnterPhase)(Object *obj, ResetType type); 107 typedef void (*ResettableHoldPhase)(Object *obj); 108 typedef void (*ResettableExitPhase)(Object *obj); 109 typedef ResettableState * (*ResettableGetState)(Object *obj); 110 typedef void (*ResettableTrFunction)(Object *obj); 111 typedef ResettableTrFunction (*ResettableGetTrFunction)(Object *obj); 112 typedef void (*ResettableChildCallback)(Object *, void *opaque, 113 ResetType type); 114 typedef void (*ResettableChildForeach)(Object *obj, 115 ResettableChildCallback cb, 116 void *opaque, ResetType type); 117 typedef struct ResettablePhases { 118 ResettableEnterPhase enter; 119 ResettableHoldPhase hold; 120 ResettableExitPhase exit; 121 } ResettablePhases; 122 typedef struct ResettableClass { 123 InterfaceClass parent_class; 124 125 /* Phase methods */ 126 ResettablePhases phases; 127 128 /* State access method */ 129 ResettableGetState get_state; 130 131 /* Transitional method for legacy reset compatibility */ 132 ResettableGetTrFunction get_transitional_function; 133 134 /* Hierarchy handling method */ 135 ResettableChildForeach child_foreach; 136 } ResettableClass; 137 138 /** 139 * ResettableState: 140 * Structure holding reset related state. The fields should not be accessed 141 * directly; the definition is here to allow further inclusion into other 142 * objects. 143 * 144 * @count: Number of reset level the object is into. It is incremented when 145 * the reset operation starts and decremented when it finishes. 146 * @hold_phase_pending: flag which indicates that we need to invoke the 'hold' 147 * phase handler for this object. 148 * @exit_phase_in_progress: true if we are currently in the exit phase 149 */ 150 struct ResettableState { 151 unsigned count; 152 bool hold_phase_pending; 153 bool exit_phase_in_progress; 154 }; 155 156 /** 157 * resettable_state_clear: 158 * Clear the state. It puts the state to the initial (zeroed) state required 159 * to reuse an object. Typically used in realize step of base classes 160 * implementing the interface. 161 */ 162 static inline void resettable_state_clear(ResettableState *state) 163 { 164 memset(state, 0, sizeof(ResettableState)); 165 } 166 167 /** 168 * resettable_reset: 169 * Trigger a reset on an object @obj of type @type. @obj must implement 170 * Resettable interface. 171 * 172 * Calling this function is equivalent to calling @resettable_assert_reset() 173 * then @resettable_release_reset(). 174 */ 175 void resettable_reset(Object *obj, ResetType type); 176 177 /** 178 * resettable_assert_reset: 179 * Put an object @obj into reset. @obj must implement Resettable interface. 180 * 181 * @resettable_release_reset() must eventually be called after this call. 182 * There must be one call to @resettable_release_reset() per call of 183 * @resettable_assert_reset(), with the same type argument. 184 * 185 * NOTE: Until support for migration is added, the @resettable_release_reset() 186 * must not be delayed. It must occur just after @resettable_assert_reset() so 187 * that migration cannot be triggered in between. Prefer using 188 * @resettable_reset() for now. 189 */ 190 void resettable_assert_reset(Object *obj, ResetType type); 191 192 /** 193 * resettable_release_reset: 194 * Release the object @obj from reset. @obj must implement Resettable interface. 195 * 196 * See @resettable_assert_reset() description for details. 197 */ 198 void resettable_release_reset(Object *obj, ResetType type); 199 200 /** 201 * resettable_is_in_reset: 202 * Return true if @obj is under reset. 203 * 204 * @obj must implement Resettable interface. 205 */ 206 bool resettable_is_in_reset(Object *obj); 207 208 /** 209 * resettable_change_parent: 210 * Indicate that the parent of Ressettable @obj is changing from @oldp to @newp. 211 * All 3 objects must implement resettable interface. @oldp or @newp may be 212 * NULL. 213 * 214 * This function will adapt the reset state of @obj so that it is coherent 215 * with the reset state of @newp. It may trigger @resettable_assert_reset() 216 * or @resettable_release_reset(). It will do such things only if the reset 217 * state of @newp and @oldp are different. 218 * 219 * When using this function during reset, it must only be called during 220 * a hold phase method. Calling this during enter or exit phase is an error. 221 */ 222 void resettable_change_parent(Object *obj, Object *newp, Object *oldp); 223 224 /** 225 * resettable_cold_reset_fn: 226 * Helper to call resettable_reset((Object *) opaque, RESET_TYPE_COLD). 227 * 228 * This function is typically useful to register a reset handler with 229 * qemu_register_reset. 230 */ 231 void resettable_cold_reset_fn(void *opaque); 232 233 /** 234 * resettable_class_set_parent_phases: 235 * 236 * Save @rc current reset phases into @parent_phases and override @rc phases 237 * by the given new methods (@enter, @hold and @exit). 238 * Each phase is overridden only if the new one is not NULL allowing to 239 * override a subset of phases. 240 */ 241 void resettable_class_set_parent_phases(ResettableClass *rc, 242 ResettableEnterPhase enter, 243 ResettableHoldPhase hold, 244 ResettableExitPhase exit, 245 ResettablePhases *parent_phases); 246 247 #endif 248