qemu

resettable.h (9304B)

---

 /*
  * Resettable interface header.
  *
  * Copyright (c) 2019 GreenSocs SAS
  *
  * Authors:
  *   Damien Hedde
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  */
 
 #ifndef HW_RESETTABLE_H
 #define HW_RESETTABLE_H
 
 #include "qom/object.h"
 
 #define TYPE_RESETTABLE_INTERFACE "resettable"
 
 typedef struct ResettableClass ResettableClass;
 DECLARE_CLASS_CHECKERS(ResettableClass, RESETTABLE,
                        TYPE_RESETTABLE_INTERFACE)
 
 
 typedef struct ResettableState ResettableState;
 
 /**
  * ResetType:
  * Types of reset.
  *
  * + Cold: reset resulting from a power cycle of the object.
  *
  * TODO: Support has to be added to handle more types. In particular,
  * ResettableState structure needs to be expanded.
  */
 typedef enum ResetType {
     RESET_TYPE_COLD,
 } ResetType;
 
 /*
  * ResettableClass:
  * Interface for resettable objects.
  *
  * See docs/devel/reset.rst for more detailed information about how QEMU models
  * reset. This whole API must only be used when holding the iothread mutex.
  *
  * All objects which can be reset must implement this interface;
  * it is usually provided by a base class such as DeviceClass or BusClass.
  * Every Resettable object must maintain some state tracking the
  * progress of a reset operation by providing a ResettableState structure.
  * The functions defined in this module take care of updating the
  * state of the reset.
  * The base class implementation of the interface provides this
  * state and implements the associated method: get_state.
  *
  * Concrete object implementations (typically specific devices
  * such as a UART model) should provide the functions
  * for the phases.enter, phases.hold and phases.exit methods, which
  * they can set in their class init function, either directly or
  * by calling resettable_class_set_parent_phases().
  * The phase methods are guaranteed to only only ever be called once
  * for any reset event, in the order 'enter', 'hold', 'exit'.
  * An object will always move quickly from 'enter' to 'hold'
  * but might remain in 'hold' for an arbitrary period of time
  * before eventually reset is deasserted and the 'exit' phase is called.
  * Object implementations should be prepared for functions handling
  * inbound connections from other devices (such as qemu_irq handler
  * functions) to be called at any point during reset after their
  * 'enter' method has been called.
  *
  * Users of a resettable object should not call these methods
  * directly, but instead use the function resettable_reset().
  *
  * @phases.enter: This phase is called when the object enters reset. It
  * should reset local state of the object, but it must not do anything that
  * has a side-effect on other objects, such as raising or lowering a qemu_irq
  * line or reading or writing guest memory. It takes the reset's type as
  * argument.
  *
  * @phases.hold: This phase is called for entry into reset, once every object
  * in the system which is being reset has had its @phases.enter method called.
  * At this point devices can do actions that affect other objects.
  *
  * @phases.exit: This phase is called when the object leaves the reset state.
  * Actions affecting other objects are permitted.
  *
  * @get_state: Mandatory method which must return a pointer to a
  * ResettableState.
  *
  * @get_transitional_function: transitional method to handle Resettable objects
  * not yet fully moved to this interface. It will be removed as soon as it is
  * not needed anymore. This method is optional and may return a pointer to a
  * function to be used instead of the phases. If the method exists and returns
  * a non-NULL function pointer then that function is executed as a replacement
  * of the 'hold' phase method taking the object as argument. The two other phase
  * methods are not executed.
  *
  * @child_foreach: Executes a given callback on every Resettable child. Child
  * in this context means a child in the qbus tree, so the children of a qbus
  * are the devices on it, and the children of a device are all the buses it
  * owns. This is not the same as the QOM object hierarchy. The function takes
  * additional opaque and ResetType arguments which must be passed unmodified to
  * the callback.
  */
 typedef void (*ResettableEnterPhase)(Object *obj, ResetType type);
 typedef void (*ResettableHoldPhase)(Object *obj);
 typedef void (*ResettableExitPhase)(Object *obj);
 typedef ResettableState * (*ResettableGetState)(Object *obj);
 typedef void (*ResettableTrFunction)(Object *obj);
 typedef ResettableTrFunction (*ResettableGetTrFunction)(Object *obj);
 typedef void (*ResettableChildCallback)(Object *, void *opaque,
                                         ResetType type);
 typedef void (*ResettableChildForeach)(Object *obj,
                                        ResettableChildCallback cb,
                                        void *opaque, ResetType type);
 typedef struct ResettablePhases {
     ResettableEnterPhase enter;
     ResettableHoldPhase hold;
     ResettableExitPhase exit;
 } ResettablePhases;
 struct ResettableClass {
     InterfaceClass parent_class;
 
     /* Phase methods */
     ResettablePhases phases;
 
     /* State access method */
     ResettableGetState get_state;
 
     /* Transitional method for legacy reset compatibility */
     ResettableGetTrFunction get_transitional_function;
 
     /* Hierarchy handling method */
     ResettableChildForeach child_foreach;
 };
 
 /**
  * ResettableState:
  * Structure holding reset related state. The fields should not be accessed
  * directly; the definition is here to allow further inclusion into other
  * objects.
  *
  * @count: Number of reset level the object is into. It is incremented when
  * the reset operation starts and decremented when it finishes.
  * @hold_phase_pending: flag which indicates that we need to invoke the 'hold'
  * phase handler for this object.
  * @exit_phase_in_progress: true if we are currently in the exit phase
  */
 struct ResettableState {
     unsigned count;
     bool hold_phase_pending;
     bool exit_phase_in_progress;
 };
 
 /**
  * resettable_state_clear:
  * Clear the state. It puts the state to the initial (zeroed) state required
  * to reuse an object. Typically used in realize step of base classes
  * implementing the interface.
  */
 static inline void resettable_state_clear(ResettableState *state)
 {
     memset(state, 0, sizeof(ResettableState));
 }
 
 /**
  * resettable_reset:
  * Trigger a reset on an object @obj of type @type. @obj must implement
  * Resettable interface.
  *
  * Calling this function is equivalent to calling @resettable_assert_reset()
  * then @resettable_release_reset().
  */
 void resettable_reset(Object *obj, ResetType type);
 
 /**
  * resettable_assert_reset:
  * Put an object @obj into reset. @obj must implement Resettable interface.
  *
  * @resettable_release_reset() must eventually be called after this call.
  * There must be one call to @resettable_release_reset() per call of
  * @resettable_assert_reset(), with the same type argument.
  *
  * NOTE: Until support for migration is added, the @resettable_release_reset()
  * must not be delayed. It must occur just after @resettable_assert_reset() so
  * that migration cannot be triggered in between. Prefer using
  * @resettable_reset() for now.
  */
 void resettable_assert_reset(Object *obj, ResetType type);
 
 /**
  * resettable_release_reset:
  * Release the object @obj from reset. @obj must implement Resettable interface.
  *
  * See @resettable_assert_reset() description for details.
  */
 void resettable_release_reset(Object *obj, ResetType type);
 
 /**
  * resettable_is_in_reset:
  * Return true if @obj is under reset.
  *
  * @obj must implement Resettable interface.
  */
 bool resettable_is_in_reset(Object *obj);
 
 /**
  * resettable_change_parent:
  * Indicate that the parent of Ressettable @obj is changing from @oldp to @newp.
  * All 3 objects must implement resettable interface. @oldp or @newp may be
  * NULL.
  *
  * This function will adapt the reset state of @obj so that it is coherent
  * with the reset state of @newp. It may trigger @resettable_assert_reset()
  * or @resettable_release_reset(). It will do such things only if the reset
  * state of @newp and @oldp are different.
  *
  * When using this function during reset, it must only be called during
  * a hold phase method. Calling this during enter or exit phase is an error.
  */
 void resettable_change_parent(Object *obj, Object *newp, Object *oldp);
 
 /**
  * resettable_cold_reset_fn:
  * Helper to call resettable_reset((Object *) opaque, RESET_TYPE_COLD).
  *
  * This function is typically useful to register a reset handler with
  * qemu_register_reset.
  */
 void resettable_cold_reset_fn(void *opaque);
 
 /**
  * resettable_class_set_parent_phases:
  *
  * Save @rc current reset phases into @parent_phases and override @rc phases
  * by the given new methods (@enter, @hold and @exit).
  * Each phase is overridden only if the new one is not NULL allowing to
  * override a subset of phases.
  */
 void resettable_class_set_parent_phases(ResettableClass *rc,
                                         ResettableEnterPhase enter,
                                         ResettableHoldPhase hold,
                                         ResettableExitPhase exit,
                                         ResettablePhases *parent_phases);
 
 #endif