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 * + Wakeup: reset resulting from a wake-up from a suspended state. 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 RESET_TYPE_SNAPSHOT_LOAD, 40 RESET_TYPE_WAKEUP, 41 RESET_TYPE_S390_CPU_INITIAL, 42 RESET_TYPE_S390_CPU_NORMAL, 43 } ResetType; 44 45 /* 46 * ResettableClass: 47 * Interface for resettable objects. 48 * 49 * See docs/devel/reset.rst for more detailed information about how QEMU models 50 * reset. This whole API must only be used when holding the iothread mutex. 51 * 52 * All objects which can be reset must implement this interface; 53 * it is usually provided by a base class such as DeviceClass or BusClass. 54 * Every Resettable object must maintain some state tracking the 55 * progress of a reset operation by providing a ResettableState structure. 56 * The functions defined in this module take care of updating the 57 * state of the reset. 58 * The base class implementation of the interface provides this 59 * state and implements the associated method: get_state. 60 * 61 * Concrete object implementations (typically specific devices 62 * such as a UART model) should provide the functions 63 * for the phases.enter, phases.hold and phases.exit methods, which 64 * they can set in their class init function, either directly or 65 * by calling resettable_class_set_parent_phases(). 66 * The phase methods are guaranteed to only only ever be called once 67 * for any reset event, in the order 'enter', 'hold', 'exit'. 68 * An object will always move quickly from 'enter' to 'hold' 69 * but might remain in 'hold' for an arbitrary period of time 70 * before eventually reset is deasserted and the 'exit' phase is called. 71 * Object implementations should be prepared for functions handling 72 * inbound connections from other devices (such as qemu_irq handler 73 * functions) to be called at any point during reset after their 74 * 'enter' method has been called. 75 * 76 * Users of a resettable object should not call these methods 77 * directly, but instead use the function resettable_reset(). 78 * 79 * @phases.enter: This phase is called when the object enters reset. It 80 * should reset local state of the object, but it must not do anything that 81 * has a side-effect on other objects, such as raising or lowering a qemu_irq 82 * line or reading or writing guest memory. It takes the reset's type as 83 * argument. 84 * 85 * @phases.hold: This phase is called for entry into reset, once every object 86 * in the system which is being reset has had its @phases.enter method called. 87 * At this point devices can do actions that affect other objects. 88 * 89 * @phases.exit: This phase is called when the object leaves the reset state. 90 * Actions affecting other objects are permitted. 91 * 92 * @get_state: Mandatory method which must return a pointer to a 93 * ResettableState. 94 * 95 * @child_foreach: Executes a given callback on every Resettable child. Child 96 * in this context means a child in the qbus tree, so the children of a qbus 97 * are the devices on it, and the children of a device are all the buses it 98 * owns. This is not the same as the QOM object hierarchy. The function takes 99 * additional opaque and ResetType arguments which must be passed unmodified to 100 * the callback. 101 */ 102 typedef void (*ResettableEnterPhase)(Object *obj, ResetType type); 103 typedef void (*ResettableHoldPhase)(Object *obj, ResetType type); 104 typedef void (*ResettableExitPhase)(Object *obj, ResetType type); 105 typedef ResettableState * (*ResettableGetState)(Object *obj); 106 typedef void (*ResettableChildCallback)(Object *, void *opaque, 107 ResetType type); 108 typedef void (*ResettableChildForeach)(Object *obj, 109 ResettableChildCallback cb, 110 void *opaque, ResetType type); 111 typedef struct ResettablePhases { 112 ResettableEnterPhase enter; 113 ResettableHoldPhase hold; 114 ResettableExitPhase exit; 115 } ResettablePhases; 116 struct ResettableClass { 117 InterfaceClass parent_class; 118 119 /* Phase methods */ 120 ResettablePhases phases; 121 122 /* State access method */ 123 ResettableGetState get_state; 124 125 /* Hierarchy handling method */ 126 ResettableChildForeach child_foreach; 127 }; 128 129 /** 130 * ResettableState: 131 * Structure holding reset related state. The fields should not be accessed 132 * directly; the definition is here to allow further inclusion into other 133 * objects. 134 * 135 * @count: Number of reset level the object is into. It is incremented when 136 * the reset operation starts and decremented when it finishes. 137 * @hold_phase_pending: flag which indicates that we need to invoke the 'hold' 138 * phase handler for this object. 139 * @exit_phase_in_progress: true if we are currently in the exit phase 140 */ 141 struct ResettableState { 142 unsigned count; 143 bool hold_phase_pending; 144 bool exit_phase_in_progress; 145 }; 146 147 /** 148 * resettable_state_clear: 149 * Clear the state. It puts the state to the initial (zeroed) state required 150 * to reuse an object. Typically used in realize step of base classes 151 * implementing the interface. 152 */ 153 static inline void resettable_state_clear(ResettableState *state) 154 { 155 memset(state, 0, sizeof(ResettableState)); 156 } 157 158 /** 159 * resettable_reset: 160 * Trigger a reset on an object @obj of type @type. @obj must implement 161 * Resettable interface. 162 * 163 * Calling this function is equivalent to calling @resettable_assert_reset() 164 * then @resettable_release_reset(). 165 */ 166 void resettable_reset(Object *obj, ResetType type); 167 168 /** 169 * resettable_assert_reset: 170 * Put an object @obj into reset. @obj must implement Resettable interface. 171 * 172 * @resettable_release_reset() must eventually be called after this call. 173 * There must be one call to @resettable_release_reset() per call of 174 * @resettable_assert_reset(), with the same type argument. 175 * 176 * NOTE: Until support for migration is added, the @resettable_release_reset() 177 * must not be delayed. It must occur just after @resettable_assert_reset() so 178 * that migration cannot be triggered in between. Prefer using 179 * @resettable_reset() for now. 180 */ 181 void resettable_assert_reset(Object *obj, ResetType type); 182 183 /** 184 * resettable_release_reset: 185 * Release the object @obj from reset. @obj must implement Resettable interface. 186 * 187 * See @resettable_assert_reset() description for details. 188 */ 189 void resettable_release_reset(Object *obj, ResetType type); 190 191 /** 192 * resettable_is_in_reset: 193 * Return true if @obj is under reset. 194 * 195 * @obj must implement Resettable interface. 196 */ 197 bool resettable_is_in_reset(Object *obj); 198 199 /** 200 * resettable_change_parent: 201 * Indicate that the parent of Ressettable @obj is changing from @oldp to @newp. 202 * All 3 objects must implement resettable interface. @oldp or @newp may be 203 * NULL. 204 * 205 * This function will adapt the reset state of @obj so that it is coherent 206 * with the reset state of @newp. It may trigger @resettable_assert_reset() 207 * or @resettable_release_reset(). It will do such things only if the reset 208 * state of @newp and @oldp are different. 209 * 210 * When using this function during reset, it must only be called during 211 * a hold phase method. Calling this during enter or exit phase is an error. 212 */ 213 void resettable_change_parent(Object *obj, Object *newp, Object *oldp); 214 215 /** 216 * resettable_cold_reset_fn: 217 * Helper to call resettable_reset((Object *) opaque, RESET_TYPE_COLD). 218 * 219 * This function is typically useful to register a reset handler with 220 * qemu_register_reset. 221 */ 222 void resettable_cold_reset_fn(void *opaque); 223 224 /** 225 * resettable_class_set_parent_phases: 226 * 227 * Save @rc current reset phases into @parent_phases and override @rc phases 228 * by the given new methods (@enter, @hold and @exit). 229 * Each phase is overridden only if the new one is not NULL allowing to 230 * override a subset of phases. 231 */ 232 void resettable_class_set_parent_phases(ResettableClass *rc, 233 ResettableEnterPhase enter, 234 ResettableHoldPhase hold, 235 ResettableExitPhase exit, 236 ResettablePhases *parent_phases); 237 238 #endif 239