xref: /qemu/include/hw/qdev-core.h (revision e57fc3dec9508cfa81c1bedcaa6b7469995ac6a5)

#ifndef QDEV_CORE_H
#define QDEV_CORE_H

#include "qemu/atomic.h"
#include "qemu/queue.h"
#include "qemu/bitmap.h"
#include "qemu/rcu.h"
#include "qemu/rcu_queue.h"
#include "qom/object.h"
#include "hw/hotplug.h"
#include "hw/resettable.h"

/**
 * DOC: The QEMU Device API
 *
 * All modern devices should represented as a derived QOM class of
 * TYPE_DEVICE. The device API introduces the additional methods of
 * @realize and @unrealize to represent additional stages in a device
 * objects life cycle.
 *
 * Realization
 * -----------
 *
 * Devices are constructed in two stages:
 *
 * 1) object instantiation via object_initialize() and
 * 2) device realization via the #DeviceState.realized property
 *
 * The former may not fail (and must not abort or exit, since it is called
 * during device introspection already), and the latter may return error
 * information to the caller and must be re-entrant.
 * Trivial field initializations should go into #TypeInfo.instance_init.
 * Operations depending on @props static properties should go into @realize.
 * After successful realization, setting static properties will fail.
 *
 * As an interim step, the #DeviceState.realized property can also be
 * set with qdev_realize(). In the future, devices will propagate this
 * state change to their children and along busses they expose. The
 * point in time will be deferred to machine creation, so that values
 * set in @realize will not be introspectable beforehand. Therefore
 * devices must not create children during @realize; they should
 * initialize them via object_initialize() in their own
 * #TypeInfo.instance_init and forward the realization events
 * appropriately.
 *
 * Any type may override the @realize and/or @unrealize callbacks but needs
 * to call the parent type's implementation if keeping their functionality
 * is desired. Refer to QOM documentation for further discussion and examples.
 *
 * .. note::
 *   Since TYPE_DEVICE doesn't implement @realize and @unrealize, types
 *   derived directly from it need not call their parent's @realize and
 *   @unrealize. For other types consult the documentation and
 *   implementation of the respective parent types.
 *
 * Hiding a device
 * ---------------
 *
 * To hide a device, a DeviceListener function hide_device() needs to
 * be registered. It can be used to defer adding a device and
 * therefore hide it from the guest. The handler registering to this
 * DeviceListener can save the QOpts passed to it for re-using it
 * later. It must return if it wants the device to be hidden or
 * visible. When the handler function decides the device shall be
 * visible it will be added with qdev_device_add() and realized as any
 * other device. Otherwise qdev_device_add() will return early without
 * adding the device. The guest will not see a "hidden" device until
 * it was marked visible and qdev_device_add called again.
 *
 */

enum {
    DEV_NVECTORS_UNSPECIFIED = -1,
};

#define TYPE_DEVICE "device"
OBJECT_DECLARE_TYPE(DeviceState, DeviceClass, DEVICE)

typedef enum DeviceCategory {
    DEVICE_CATEGORY_BRIDGE,
    DEVICE_CATEGORY_USB,
    DEVICE_CATEGORY_STORAGE,
    DEVICE_CATEGORY_NETWORK,
    DEVICE_CATEGORY_INPUT,
    DEVICE_CATEGORY_DISPLAY,
    DEVICE_CATEGORY_SOUND,
    DEVICE_CATEGORY_MISC,
    DEVICE_CATEGORY_CPU,
    DEVICE_CATEGORY_WATCHDOG,
    DEVICE_CATEGORY_MAX
} DeviceCategory;

typedef void (*DeviceRealize)(DeviceState *dev, Error **errp);
typedef void (*DeviceUnrealize)(DeviceState *dev);
typedef void (*DeviceReset)(DeviceState *dev);
typedef void (*BusRealize)(BusState *bus, Error **errp);
typedef void (*BusUnrealize)(BusState *bus);

/**
 * struct DeviceClass - The base class for all devices.
 * @props: Properties accessing state fields.
 * @realize: Callback function invoked when the #DeviceState:realized
 * property is changed to %true.
 * @unrealize: Callback function invoked when the #DeviceState:realized
 * property is changed to %false.
 * @hotpluggable: indicates if #DeviceClass is hotpluggable, available
 * as readonly "hotpluggable" property of #DeviceState instance
 *
 */
struct DeviceClass {
    /* private: */
    ObjectClass parent_class;

    /* public: */

    /**
     * @categories: device categories device belongs to
     */
    DECLARE_BITMAP(categories, DEVICE_CATEGORY_MAX);
    /**
     * @fw_name: name used to identify device to firmware interfaces
     */
    const char *fw_name;
    /**
     * @desc: human readable description of device
     */
    const char *desc;

    /**
     * @props_: properties associated with device, should only be
     * assigned by using device_class_set_props(). The underscore
     * ensures a compile-time error if someone attempts to assign
     * dc->props directly.
     */
    Property *props_;

    /**
     * @user_creatable: Can user instantiate with -device / device_add?
     *
     * All devices should support instantiation with device_add, and
     * this flag should not exist.  But we're not there, yet.  Some
     * devices fail to instantiate with cryptic error messages.
     * Others instantiate, but don't work.  Exposing users to such
     * behavior would be cruel; clearing this flag will protect them.
     * It should never be cleared without a comment explaining why it
     * is cleared.
     *
     * TODO remove once we're there
     */
    bool user_creatable;
    bool hotpluggable;

    /* callbacks */
    /**
     * @reset: deprecated device reset method pointer
     *
     * Modern code should use the ResettableClass interface to
     * implement a multi-phase reset.
     *
     * TODO: remove once every reset callback is unused
     */
    DeviceReset reset;
    DeviceRealize realize;
    DeviceUnrealize unrealize;

    /**
     * @vmsd: device state serialisation description for
     * migration/save/restore
     */
    const VMStateDescription *vmsd;

    /**
     * @bus_type: bus type
     * private: to qdev / bus.
     */
    const char *bus_type;
};

typedef struct NamedGPIOList NamedGPIOList;

struct NamedGPIOList {
    char *name;
    qemu_irq *in;
    int num_in;
    int num_out;
    QLIST_ENTRY(NamedGPIOList) node;
};

typedef struct Clock Clock;
typedef struct NamedClockList NamedClockList;

struct NamedClockList {
    char *name;
    Clock *clock;
    bool output;
    bool alias;
    QLIST_ENTRY(NamedClockList) node;
};

typedef struct {
    bool engaged_in_io;
} MemReentrancyGuard;


typedef QLIST_HEAD(, NamedGPIOList) NamedGPIOListHead;
typedef QLIST_HEAD(, NamedClockList) NamedClockListHead;
typedef QLIST_HEAD(, BusState) BusStateHead;

/**
 * struct DeviceState - common device state, accessed with qdev helpers
 *
 * This structure should not be accessed directly.  We declare it here
 * so that it can be embedded in individual device state structures.
 */
struct DeviceState {
    /* private: */
    Object parent_obj;
    /* public: */

    /**
     * @id: global device id
     */
    char *id;
    /**
     * @canonical_path: canonical path of realized device in the QOM tree
     */
    char *canonical_path;
    /**
     * @realized: has device been realized?
     */
    bool realized;
    /**
     * @pending_deleted_event: track pending deletion events during unplug
     */
    bool pending_deleted_event;
    /**
     * @pending_deleted_expires_ms: optional timeout for deletion events
     */
    int64_t pending_deleted_expires_ms;
    /**
     * @opts: QDict of options for the device
     */
    QDict *opts;
    /**
     * @hotplugged: was device added after PHASE_MACHINE_READY?
     */
    int hotplugged;
    /**
     * @allow_unplug_during_migration: can device be unplugged during migration
     */
    bool allow_unplug_during_migration;
    /**
     * @parent_bus: bus this device belongs to
     */
    BusState *parent_bus;
    /**
     * @gpios: QLIST of named GPIOs the device provides.
     */
    NamedGPIOListHead gpios;
    /**
     * @clocks: QLIST of named clocks the device provides.
     */
    NamedClockListHead clocks;
    /**
     * @child_bus: QLIST of child buses
     */
    BusStateHead child_bus;
    /**
     * @num_child_bus: number of @child_bus entries
     */
    int num_child_bus;
    /**
     * @instance_id_alias: device alias for handling legacy migration setups
     */
    int instance_id_alias;
    /**
     * @alias_required_for_version: indicates @instance_id_alias is
     * needed for migration
     */
    int alias_required_for_version;
    /**
     * @reset: ResettableState for the device; handled by Resettable interface.
     */
    ResettableState reset;
    /**
     * @unplug_blockers: list of reasons to block unplugging of device
     */
    GSList *unplug_blockers;
    /**
     * @mem_reentrancy_guard: Is the device currently in mmio/pio/dma?
     *
     * Used to prevent re-entrancy confusing things.
     */
    MemReentrancyGuard mem_reentrancy_guard;
};

struct DeviceListener {
    void (*realize)(DeviceListener *listener, DeviceState *dev);
    void (*unrealize)(DeviceListener *listener, DeviceState *dev);
    /*
     * This callback is called upon init of the DeviceState and
     * informs qdev if a device should be visible or hidden.  We can
     * hide a failover device depending for example on the device
     * opts.
     *
     * On errors, it returns false and errp is set. Device creation
     * should fail in this case.
     */
    bool (*hide_device)(DeviceListener *listener, const QDict *device_opts,
                        bool from_json, Error **errp);
    QTAILQ_ENTRY(DeviceListener) link;
};

#define TYPE_BUS "bus"
DECLARE_OBJ_CHECKERS(BusState, BusClass,
                     BUS, TYPE_BUS)

struct BusClass {
    ObjectClass parent_class;

    /* FIXME first arg should be BusState */
    void (*print_dev)(Monitor *mon, DeviceState *dev, int indent);
    char *(*get_dev_path)(DeviceState *dev);

    /*
     * This callback is used to create Open Firmware device path in accordance
     * with OF spec http://forthworks.com/standards/of1275.pdf. Individual bus
     * bindings can be found at http://playground.sun.com/1275/bindings/.
     */
    char *(*get_fw_dev_path)(DeviceState *dev);

    void (*reset)(BusState *bus);

    /*
     * Return whether the device can be added to @bus,
     * based on the address that was set (via device properties)
     * before realize.  If not, on return @errp contains the
     * human-readable error message.
     */
    bool (*check_address)(BusState *bus, DeviceState *dev, Error **errp);

    BusRealize realize;
    BusUnrealize unrealize;

    /* maximum devices allowed on the bus, 0: no limit. */
    int max_dev;
    /* number of automatically allocated bus ids (e.g. ide.0) */
    int automatic_ids;
};

typedef struct BusChild {
    struct rcu_head rcu;
    DeviceState *child;
    int index;
    QTAILQ_ENTRY(BusChild) sibling;
} BusChild;

#define QDEV_HOTPLUG_HANDLER_PROPERTY "hotplug-handler"

typedef QTAILQ_HEAD(, BusChild) BusChildHead;
typedef QLIST_ENTRY(BusState) BusStateEntry;

/**
 * struct BusState:
 * @obj: parent object
 * @parent: parent Device
 * @name: name of bus
 * @hotplug_handler: link to a hotplug handler associated with bus.
 * @max_index: max number of child buses
 * @realized: is the bus itself realized?
 * @full: is the bus full?
 * @num_children: current number of child buses
 */
struct BusState {
    /* private: */
    Object obj;
    /* public: */
    DeviceState *parent;
    char *name;
    HotplugHandler *hotplug_handler;
    int max_index;
    bool realized;
    bool full;
    int num_children;

    /**
     * @children: an RCU protected QTAILQ, thus readers must use RCU
     * to access it, and writers must hold the big qemu lock
     */
    BusChildHead children;
    /**
     * @sibling: next bus
     */
    BusStateEntry sibling;
    /**
     * @reset: ResettableState for the bus; handled by Resettable interface.
     */
    ResettableState reset;
};

/**
 * typedef GlobalProperty - a global property type
 *
 * @used: Set to true if property was used when initializing a device.
 * @optional: If set to true, GlobalProperty will be skipped without errors
 *            if the property doesn't exist.
 *
 * An error is fatal for non-hotplugged devices, when the global is applied.
 */
typedef struct GlobalProperty {
    const char *driver;
    const char *property;
    const char *value;
    bool used;
    bool optional;
} GlobalProperty;

static inline void
compat_props_add(GPtrArray *arr,
                 GlobalProperty props[], size_t nelem)
{
    int i;
    for (i = 0; i < nelem; i++) {
        g_ptr_array_add(arr, (void *)&props[i]);
    }
}

/*** Board API.  This should go away once we have a machine config file.  ***/

/**
 * qdev_new: Create a device on the heap
 * @name: device type to create (we assert() that this type exists)
 *
 * This only allocates the memory and initializes the device state
 * structure, ready for the caller to set properties if they wish.
 * The device still needs to be realized.
 *
 * Return: a derived DeviceState object with a reference count of 1.
 */
DeviceState *qdev_new(const char *name);

/**
 * qdev_try_new: Try to create a device on the heap
 * @name: device type to create
 *
 * This is like qdev_new(), except it returns %NULL when type @name
 * does not exist, rather than asserting.
 *
 * Return: a derived DeviceState object with a reference count of 1 or
 * NULL if type @name does not exist.
 */
DeviceState *qdev_try_new(const char *name);

/**
 * qdev_is_realized() - check if device is realized
 * @dev: The device to check.
 *
 * Context: May be called outside big qemu lock.
 * Return: true if the device has been fully constructed, false otherwise.
 */
static inline bool qdev_is_realized(DeviceState *dev)
{
    return qatomic_load_acquire(&dev->realized);
}

/**
 * qdev_realize: Realize @dev.
 * @dev: device to realize
 * @bus: bus to plug it into (may be NULL)
 * @errp: pointer to error object
 *
 * "Realize" the device, i.e. perform the second phase of device
 * initialization.
 * @dev must not be plugged into a bus already.
 * If @bus, plug @dev into @bus.  This takes a reference to @dev.
 * If @dev has no QOM parent, make one up, taking another reference.
 *
 * If you created @dev using qdev_new(), you probably want to use
 * qdev_realize_and_unref() instead.
 *
 * Return: true on success, else false setting @errp with error
 */
bool qdev_realize(DeviceState *dev, BusState *bus, Error **errp);

/**
 * qdev_realize_and_unref: Realize @dev and drop a reference
 * @dev: device to realize
 * @bus: bus to plug it into (may be NULL)
 * @errp: pointer to error object
 *
 * Realize @dev and drop a reference.
 * This is like qdev_realize(), except the caller must hold a
 * (private) reference, which is dropped on return regardless of
 * success or failure.  Intended use::
 *
 *     dev = qdev_new();
 *     [...]
 *     qdev_realize_and_unref(dev, bus, errp);
 *
 * Now @dev can go away without further ado.
 *
 * If you are embedding the device into some other QOM device and
 * initialized it via some variant on object_initialize_child() then
 * do not use this function, because that family of functions arrange
 * for the only reference to the child device to be held by the parent
 * via the child<> property, and so the reference-count-drop done here
 * would be incorrect. For that use case you want qdev_realize().
 *
 * Return: true on success, else false setting @errp with error
 */
bool qdev_realize_and_unref(DeviceState *dev, BusState *bus, Error **errp);

/**
 * qdev_unrealize: Unrealize a device
 * @dev: device to unrealize
 *
 * This function will "unrealize" a device, which is the first phase
 * of correctly destroying a device that has been realized. It will:
 *
 *  - unrealize any child buses by calling qbus_unrealize()
 *    (this will recursively unrealize any devices on those buses)
 *  - call the unrealize method of @dev
 *
 * The device can then be freed by causing its reference count to go
 * to zero.
 *
 * Warning: most devices in QEMU do not expect to be unrealized.  Only
 * devices which are hot-unpluggable should be unrealized (as part of
 * the unplugging process); all other devices are expected to last for
 * the life of the simulation and should not be unrealized and freed.
 */
void qdev_unrealize(DeviceState *dev);
void qdev_set_legacy_instance_id(DeviceState *dev, int alias_id,
                                 int required_for_version);
HotplugHandler *qdev_get_bus_hotplug_handler(DeviceState *dev);
HotplugHandler *qdev_get_machine_hotplug_handler(DeviceState *dev);
bool qdev_hotplug_allowed(DeviceState *dev, Error **errp);

/**
 * qdev_get_hotplug_handler() - Get handler responsible for device wiring
 * @dev: the device we want the HOTPLUG_HANDLER for.
 *
 * Note: in case @dev has a parent bus, it will be returned as handler unless
 * machine handler overrides it.
 *
 * Return: pointer to object that implements TYPE_HOTPLUG_HANDLER interface
 * or NULL if there aren't any.
 */
HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev);
void qdev_unplug(DeviceState *dev, Error **errp);
void qdev_simple_device_unplug_cb(HotplugHandler *hotplug_dev,
                                  DeviceState *dev, Error **errp);
void qdev_machine_creation_done(void);
bool qdev_machine_modified(void);

/**
 * qdev_add_unplug_blocker: Add an unplug blocker to a device
 *
 * @dev: Device to be blocked from unplug
 * @reason: Reason for blocking
 */
void qdev_add_unplug_blocker(DeviceState *dev, Error *reason);

/**
 * qdev_del_unplug_blocker: Remove an unplug blocker from a device
 *
 * @dev: Device to be unblocked
 * @reason: Pointer to the Error used with qdev_add_unplug_blocker.
 *          Used as a handle to lookup the blocker for deletion.
 */
void qdev_del_unplug_blocker(DeviceState *dev, Error *reason);

/**
 * qdev_unplug_blocked: Confirm if a device is blocked from unplug
 *
 * @dev: Device to be tested
 * @errp: The reasons why the device is blocked, if any
 *
 * Returns: true (also setting @errp) if device is blocked from unplug,
 * false otherwise
 */
bool qdev_unplug_blocked(DeviceState *dev, Error **errp);

/**
 * typedef GpioPolarity - Polarity of a GPIO line
 *
 * GPIO lines use either positive (active-high) logic,
 * or negative (active-low) logic.
 *
 * In active-high logic (%GPIO_POLARITY_ACTIVE_HIGH), a pin is
 * active when the voltage on the pin is high (relative to ground);
 * whereas in active-low logic (%GPIO_POLARITY_ACTIVE_LOW), a pin
 * is active when the voltage on the pin is low (or grounded).
 */
typedef enum {
    GPIO_POLARITY_ACTIVE_LOW,
    GPIO_POLARITY_ACTIVE_HIGH
} GpioPolarity;

/**
 * qdev_get_gpio_in: Get one of a device's anonymous input GPIO lines
 * @dev: Device whose GPIO we want
 * @n: Number of the anonymous GPIO line (which must be in range)
 *
 * Returns the qemu_irq corresponding to an anonymous input GPIO line
 * (which the device has set up with qdev_init_gpio_in()). The index
 * @n of the GPIO line must be valid (i.e. be at least 0 and less than
 * the total number of anonymous input GPIOs the device has); this
 * function will assert() if passed an invalid index.
 *
 * This function is intended to be used by board code or SoC "container"
 * device models to wire up the GPIO lines; usually the return value
 * will be passed to qdev_connect_gpio_out() or a similar function to
 * connect another device's output GPIO line to this input.
 *
 * For named input GPIO lines, use qdev_get_gpio_in_named().
 *
 * Return: qemu_irq corresponding to anonymous input GPIO line
 */
qemu_irq qdev_get_gpio_in(DeviceState *dev, int n);

/**
 * qdev_get_gpio_in_named: Get one of a device's named input GPIO lines
 * @dev: Device whose GPIO we want
 * @name: Name of the input GPIO array
 * @n: Number of the GPIO line in that array (which must be in range)
 *
 * Returns the qemu_irq corresponding to a named input GPIO line
 * (which the device has set up with qdev_init_gpio_in_named()).
 * The @name string must correspond to an input GPIO array which exists on
 * the device, and the index @n of the GPIO line must be valid (i.e.
 * be at least 0 and less than the total number of input GPIOs in that
 * array); this function will assert() if passed an invalid name or index.
 *
 * For anonymous input GPIO lines, use qdev_get_gpio_in().
 *
 * Return: qemu_irq corresponding to named input GPIO line
 */
qemu_irq qdev_get_gpio_in_named(DeviceState *dev, const char *name, int n);

/**
 * qdev_connect_gpio_out: Connect one of a device's anonymous output GPIO lines
 * @dev: Device whose GPIO to connect
 * @n: Number of the anonymous output GPIO line (which must be in range)
 * @pin: qemu_irq to connect the output line to
 *
 * This function connects an anonymous output GPIO line on a device
 * up to an arbitrary qemu_irq, so that when the device asserts that
 * output GPIO line, the qemu_irq's callback is invoked.
 * The index @n of the GPIO line must be valid (i.e. be at least 0 and
 * less than the total number of anonymous output GPIOs the device has
 * created with qdev_init_gpio_out()); otherwise this function will assert().
 *
 * Outbound GPIO lines can be connected to any qemu_irq, but the common
 * case is connecting them to another device's inbound GPIO line, using
 * the qemu_irq returned by qdev_get_gpio_in() or qdev_get_gpio_in_named().
 *
 * It is not valid to try to connect one outbound GPIO to multiple
 * qemu_irqs at once, or to connect multiple outbound GPIOs to the
 * same qemu_irq. (Warning: there is no assertion or other guard to
 * catch this error: the model will just not do the right thing.)
 * Instead, for fan-out you can use the TYPE_SPLIT_IRQ device: connect
 * a device's outbound GPIO to the splitter's input, and connect each
 * of the splitter's outputs to a different device.  For fan-in you
 * can use the TYPE_OR_IRQ device, which is a model of a logical OR
 * gate with multiple inputs and one output.
 *
 * For named output GPIO lines, use qdev_connect_gpio_out_named().
 */
void qdev_connect_gpio_out(DeviceState *dev, int n, qemu_irq pin);

/**
 * qdev_connect_gpio_out_named: Connect one of a device's named output
 *                              GPIO lines
 * @dev: Device whose GPIO to connect
 * @name: Name of the output GPIO array
 * @n: Number of the anonymous output GPIO line (which must be in range)
 * @input_pin: qemu_irq to connect the output line to
 *
 * This function connects an anonymous output GPIO line on a device
 * up to an arbitrary qemu_irq, so that when the device asserts that
 * output GPIO line, the qemu_irq's callback is invoked.
 * The @name string must correspond to an output GPIO array which exists on
 * the device, and the index @n of the GPIO line must be valid (i.e.
 * be at least 0 and less than the total number of input GPIOs in that
 * array); this function will assert() if passed an invalid name or index.
 *
 * Outbound GPIO lines can be connected to any qemu_irq, but the common
 * case is connecting them to another device's inbound GPIO line, using
 * the qemu_irq returned by qdev_get_gpio_in() or qdev_get_gpio_in_named().
 *
 * It is not valid to try to connect one outbound GPIO to multiple
 * qemu_irqs at once, or to connect multiple outbound GPIOs to the
 * same qemu_irq; see qdev_connect_gpio_out() for details.
 *
 * For anonymous output GPIO lines, use qdev_connect_gpio_out().
 */
void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
                                 qemu_irq input_pin);

/**
 * qdev_get_gpio_out_connector: Get the qemu_irq connected to an output GPIO
 * @dev: Device whose output GPIO we are interested in
 * @name: Name of the output GPIO array
 * @n: Number of the output GPIO line within that array
 *
 * Returns whatever qemu_irq is currently connected to the specified
 * output GPIO line of @dev. This will be NULL if the output GPIO line
 * has never been wired up to the anything.  Note that the qemu_irq
 * returned does not belong to @dev -- it will be the input GPIO or
 * IRQ of whichever device the board code has connected up to @dev's
 * output GPIO.
 *
 * You probably don't need to use this function -- it is used only
 * by the platform-bus subsystem.
 *
 * Return: qemu_irq associated with GPIO or NULL if un-wired.
 */
qemu_irq qdev_get_gpio_out_connector(DeviceState *dev, const char *name, int n);

/**
 * qdev_intercept_gpio_out: Intercept an existing GPIO connection
 * @dev: Device to intercept the outbound GPIO line from
 * @icpt: New qemu_irq to connect instead
 * @name: Name of the output GPIO array
 * @n: Number of the GPIO line in the array
 *
 * .. note::
 *   This function is provided only for use by the qtest testing framework
 *   and is not suitable for use in non-testing parts of QEMU.
 *
 * This function breaks an existing connection of an outbound GPIO
 * line from @dev, and replaces it with the new qemu_irq @icpt, as if
 * ``qdev_connect_gpio_out_named(dev, icpt, name, n)`` had been called.
 * The previously connected qemu_irq is returned, so it can be restored
 * by a second call to qdev_intercept_gpio_out() if desired.
 *
 * Return: old disconnected qemu_irq if one existed
 */
qemu_irq qdev_intercept_gpio_out(DeviceState *dev, qemu_irq icpt,
                                 const char *name, int n);

BusState *qdev_get_child_bus(DeviceState *dev, const char *name);

/*** Device API.  ***/

/**
 * qdev_init_gpio_in: create an array of anonymous input GPIO lines
 * @dev: Device to create input GPIOs for
 * @handler: Function to call when GPIO line value is set
 * @n: Number of GPIO lines to create
 *
 * Devices should use functions in the qdev_init_gpio_in* family in
 * their instance_init or realize methods to create any input GPIO
 * lines they need. There is no functional difference between
 * anonymous and named GPIO lines. Stylistically, named GPIOs are
 * preferable (easier to understand at callsites) unless a device
 * has exactly one uniform kind of GPIO input whose purpose is obvious.
 * Note that input GPIO lines can serve as 'sinks' for IRQ lines.
 *
 * See qdev_get_gpio_in() for how code that uses such a device can get
 * hold of an input GPIO line to manipulate it.
 */
void qdev_init_gpio_in(DeviceState *dev, qemu_irq_handler handler, int n);

/**
 * qdev_init_gpio_out: create an array of anonymous output GPIO lines
 * @dev: Device to create output GPIOs for
 * @pins: Pointer to qemu_irq or qemu_irq array for the GPIO lines
 * @n: Number of GPIO lines to create
 *
 * Devices should use functions in the qdev_init_gpio_out* family
 * in their instance_init or realize methods to create any output
 * GPIO lines they need. There is no functional difference between
 * anonymous and named GPIO lines. Stylistically, named GPIOs are
 * preferable (easier to understand at callsites) unless a device
 * has exactly one uniform kind of GPIO output whose purpose is obvious.
 *
 * The @pins argument should be a pointer to either a "qemu_irq"
 * (if @n == 1) or a "qemu_irq []" array (if @n > 1) in the device's
 * state structure. The device implementation can then raise and
 * lower the GPIO line by calling qemu_set_irq(). (If anything is
 * connected to the other end of the GPIO this will cause the handler
 * function for that input GPIO to be called.)
 *
 * See qdev_connect_gpio_out() for how code that uses such a device
 * can connect to one of its output GPIO lines.
 *
 * There is no need to release the @pins allocated array because it
 * will be automatically released when @dev calls its instance_finalize()
 * handler.
 */
void qdev_init_gpio_out(DeviceState *dev, qemu_irq *pins, int n);

/**
 * qdev_init_gpio_out_named: create an array of named output GPIO lines
 * @dev: Device to create output GPIOs for
 * @pins: Pointer to qemu_irq or qemu_irq array for the GPIO lines
 * @name: Name to give this array of GPIO lines
 * @n: Number of GPIO lines to create
 *
 * Like qdev_init_gpio_out(), but creates an array of GPIO output lines
 * with a name. Code using the device can then connect these GPIO lines
 * using qdev_connect_gpio_out_named().
 */
void qdev_init_gpio_out_named(DeviceState *dev, qemu_irq *pins,
                              const char *name, int n);

/**
 * qdev_init_gpio_in_named_with_opaque() - create an array of input GPIO lines
 * @dev: Device to create input GPIOs for
 * @handler: Function to call when GPIO line value is set
 * @opaque: Opaque data pointer to pass to @handler
 * @name: Name of the GPIO input (must be unique for this device)
 * @n: Number of GPIO lines in this input set
 */
void qdev_init_gpio_in_named_with_opaque(DeviceState *dev,
                                         qemu_irq_handler handler,
                                         void *opaque,
                                         const char *name, int n);

/**
 * qdev_init_gpio_in_named() - create an array of input GPIO lines
 * @dev: device to add array to
 * @handler: a &typedef qemu_irq_handler function to call when GPIO is set
 * @name: Name of the GPIO input (must be unique for this device)
 * @n: Number of GPIO lines in this input set
 *
 * Like qdev_init_gpio_in_named_with_opaque(), but the opaque pointer
 * passed to the handler is @dev (which is the most commonly desired behaviour).
 */
static inline void qdev_init_gpio_in_named(DeviceState *dev,
                                           qemu_irq_handler handler,
                                           const char *name, int n)
{
    qdev_init_gpio_in_named_with_opaque(dev, handler, dev, name, n);
}

/**
 * qdev_pass_gpios: create GPIO lines on container which pass through to device
 * @dev: Device which has GPIO lines
 * @container: Container device which needs to expose them
 * @name: Name of GPIO array to pass through (NULL for the anonymous GPIO array)
 *
 * In QEMU, complicated devices like SoCs are often modelled with a
 * "container" QOM device which itself contains other QOM devices and
 * which wires them up appropriately. This function allows the container
 * to create GPIO arrays on itself which simply pass through to a GPIO
 * array of one of its internal devices.
 *
 * If @dev has both input and output GPIOs named @name then both will
 * be passed through. It is not possible to pass a subset of the array
 * with this function.
 *
 * To users of the container device, the GPIO array created on @container
 * behaves exactly like any other.
 */
void qdev_pass_gpios(DeviceState *dev, DeviceState *container,
                     const char *name);

BusState *qdev_get_parent_bus(const DeviceState *dev);

/*** BUS API. ***/

DeviceState *qdev_find_recursive(BusState *bus, const char *id);

/* Returns 0 to walk children, > 0 to skip walk, < 0 to terminate walk. */
typedef int (qbus_walkerfn)(BusState *bus, void *opaque);
typedef int (qdev_walkerfn)(DeviceState *dev, void *opaque);

void qbus_init(void *bus, size_t size, const char *typename,
               DeviceState *parent, const char *name);
BusState *qbus_new(const char *typename, DeviceState *parent, const char *name);
bool qbus_realize(BusState *bus, Error **errp);
void qbus_unrealize(BusState *bus);

/* Returns > 0 if either devfn or busfn skip walk somewhere in cursion,
 *         < 0 if either devfn or busfn terminate walk somewhere in cursion,
 *           0 otherwise. */
int qbus_walk_children(BusState *bus,
                       qdev_walkerfn *pre_devfn, qbus_walkerfn *pre_busfn,
                       qdev_walkerfn *post_devfn, qbus_walkerfn *post_busfn,
                       void *opaque);
int qdev_walk_children(DeviceState *dev,
                       qdev_walkerfn *pre_devfn, qbus_walkerfn *pre_busfn,
                       qdev_walkerfn *post_devfn, qbus_walkerfn *post_busfn,
                       void *opaque);

/**
 * device_cold_reset() - perform a recursive cold reset on a device
 * @dev: device to reset.
 *
 * Reset device @dev and perform a recursive processing using the resettable
 * interface. It triggers a RESET_TYPE_COLD.
 */
void device_cold_reset(DeviceState *dev);

/**
 * bus_cold_reset() - perform a recursive cold reset on a bus
 * @bus: bus to reset
 *
 * Reset bus @bus and perform a recursive processing using the resettable
 * interface. It triggers a RESET_TYPE_COLD.
 */
void bus_cold_reset(BusState *bus);

/**
 * device_is_in_reset() - check device reset state
 * @dev: device to check
 *
 * Return: true if the device @dev is currently being reset.
 */
bool device_is_in_reset(DeviceState *dev);

/**
 * bus_is_in_reset() - check bus reset state
 * @bus: bus to check
 *
 * Return: true if the bus @bus is currently being reset.
 */
bool bus_is_in_reset(BusState *bus);

/* This should go away once we get rid of the NULL bus hack */
BusState *sysbus_get_default(void);

char *qdev_get_fw_dev_path(DeviceState *dev);
char *qdev_get_own_fw_dev_path_from_handler(BusState *bus, DeviceState *dev);

/**
 * device_class_set_props(): add a set of properties to an device
 * @dc: the parent DeviceClass all devices inherit
 * @props: an array of properties, terminate by DEFINE_PROP_END_OF_LIST()
 *
 * This will add a set of properties to the object. It will fault if
 * you attempt to add an existing property defined by a parent class.
 * To modify an inherited property you need to use????
 */
void device_class_set_props(DeviceClass *dc, Property *props);

/**
 * device_class_set_parent_reset() - legacy set device reset handlers
 * @dc: device class
 * @dev_reset: function pointer to reset handler
 * @parent_reset: function pointer to parents reset handler
 *
 * Modern code should use the ResettableClass interface to
 * implement a multi-phase reset instead.
 *
 * TODO: remove the function when DeviceClass's reset method
 * is not used anymore.
 */
void device_class_set_parent_reset(DeviceClass *dc,
                                   DeviceReset dev_reset,
                                   DeviceReset *parent_reset);
void device_class_set_parent_realize(DeviceClass *dc,
                                     DeviceRealize dev_realize,
                                     DeviceRealize *parent_realize);
void device_class_set_parent_unrealize(DeviceClass *dc,
                                       DeviceUnrealize dev_unrealize,
                                       DeviceUnrealize *parent_unrealize);

const VMStateDescription *qdev_get_vmsd(DeviceState *dev);

const char *qdev_fw_name(DeviceState *dev);

void qdev_assert_realized_properly(void);
Object *qdev_get_machine(void);

/* FIXME: make this a link<> */
bool qdev_set_parent_bus(DeviceState *dev, BusState *bus, Error **errp);

extern bool qdev_hot_removed;

char *qdev_get_dev_path(DeviceState *dev);

void qbus_set_hotplug_handler(BusState *bus, Object *handler);
void qbus_set_bus_hotplug_handler(BusState *bus);

static inline bool qbus_is_hotpluggable(BusState *bus)
{
    HotplugHandler *plug_handler = bus->hotplug_handler;
    bool ret = !!plug_handler;

    if (plug_handler) {
        HotplugHandlerClass *hdc;

        hdc = HOTPLUG_HANDLER_GET_CLASS(plug_handler);
        if (hdc->is_hotpluggable_bus) {
            ret = hdc->is_hotpluggable_bus(plug_handler, bus);
        }
    }
    return ret;
}

/**
 * qbus_mark_full: Mark this bus as full, so no more devices can be attached
 * @bus: Bus to mark as full
 *
 * By default, QEMU will allow devices to be plugged into a bus up
 * to the bus class's device count limit. Calling this function
 * marks a particular bus as full, so that no more devices can be
 * plugged into it. In particular this means that the bus will not
 * be considered as a candidate for plugging in devices created by
 * the user on the commandline or via the monitor.
 * If a machine has multiple buses of a given type, such as I2C,
 * where some of those buses in the real hardware are used only for
 * internal devices and some are exposed via expansion ports, you
 * can use this function to mark the internal-only buses as full
 * after you have created all their internal devices. Then user
 * created devices will appear on the expansion-port bus where
 * guest software expects them.
 */
static inline void qbus_mark_full(BusState *bus)
{
    bus->full = true;
}

void device_listener_register(DeviceListener *listener);
void device_listener_unregister(DeviceListener *listener);

/**
 * qdev_should_hide_device() - check if device should be hidden
 *
 * @opts: options QDict
 * @from_json: true if @opts entries are typed, false for all strings
 * @errp: pointer to error object
 *
 * When a device is added via qdev_device_add() this will be called.
 *
 * Return: if the device should be added now or not.
 */
bool qdev_should_hide_device(const QDict *opts, bool from_json, Error **errp);

typedef enum MachineInitPhase {
    /* current_machine is NULL.  */
    PHASE_NO_MACHINE,

    /* current_machine is not NULL, but current_machine->accel is NULL.  */
    PHASE_MACHINE_CREATED,

    /*
     * current_machine->accel is not NULL, but the machine properties have
     * not been validated and machine_class->init has not yet been called.
     */
    PHASE_ACCEL_CREATED,

    /*
     * machine_class->init has been called, thus creating any embedded
     * devices and validating machine properties.  Devices created at
     * this time are considered to be cold-plugged.
     */
    PHASE_MACHINE_INITIALIZED,

    /*
     * QEMU is ready to start CPUs and devices created at this time
     * are considered to be hot-plugged.  The monitor is not restricted
     * to "preconfig" commands.
     */
    PHASE_MACHINE_READY,
} MachineInitPhase;

extern bool phase_check(MachineInitPhase phase);
extern void phase_advance(MachineInitPhase phase);

#endif