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