[Qemu-devel] [RFC PATCH 03/17] make Device and Bus Resettable

[Damien Hedde]

This add Resettable interface implementation for both Bus and Device.
The init phase default implementation is to call the legacy reset
handler.

Add a *resetting* counter in both Device and Bus. This counter allows us to
handle reentrancy in reset operation. If a device/bus has multiple
source triggering reset, theses sources do not have to care about the
current device/bus resetting state. Each source can independantly assert
and eventually deassert the reset. The device/bus will behave as expected and
gets out-of-reset state only when all sources have deasserted the reset.

Signed-off-by: Damien Hedde <address@hidden>
---
 hw/core/bus.c          | 60 +++++++++++++++++++++++++++++++++++++++++
 hw/core/qdev.c         | 61 ++++++++++++++++++++++++++++++++++++++++++
 include/hw/qdev-core.h | 30 +++++++++++++++++++++
 3 files changed, 151 insertions(+)

diff --git a/hw/core/bus.c b/hw/core/bus.c
index e09843f6ab..0a60bb4b24 100644
--- a/hw/core/bus.c
+++ b/hw/core/bus.c
@@ -21,6 +21,7 @@
 #include "qemu-common.h"
 #include "hw/qdev.h"
 #include "qapi/error.h"
+#include "hw/resettable.h"
 
 void qbus_set_hotplug_handler(BusState *bus, Object *handler, Error **errp)
 {
@@ -67,6 +68,56 @@ int qbus_walk_children(BusState *bus,
     return 0;
 }
 
+void qbus_reset(BusState *bus, bool cold)
+{
+    resettable_reset(OBJECT(bus), cold);
+}
+
+bool qbus_is_resetting(BusState *bus)
+{
+    return (bus->resetting != 0);
+}
+
+static void bus_reset_init_phase(Object *obj, bool cold)
+{
+    BusState *bus = BUS(obj);
+    BusClass *bc = BUS_GET_CLASS(obj);
+    BusChild *kid;
+
+    QTAILQ_FOREACH(kid, &bus->children, sibling) {
+        resettable_init_phase(OBJECT(kid->child), cold);
+    }
+
+    bus->resetting += 1;
+
+    if (bc->reset) {
+        bc->reset(bus);
+    }
+}
+
+static void bus_reset_hold_phase(Object *obj)
+{
+    BusState *bus = BUS(obj);
+    BusChild *kid;
+
+    QTAILQ_FOREACH(kid, &bus->children, sibling) {
+        resettable_hold_phase(OBJECT(kid->child));
+    }
+}
+
+static void bus_reset_exit_phase(Object *obj)
+{
+    BusState *bus = BUS(obj);
+    BusChild *kid;
+
+    QTAILQ_FOREACH(kid, &bus->children, sibling) {
+        resettable_exit_phase(OBJECT(kid->child));
+    }
+
+    assert(bus->resetting > 0);
+    bus->resetting -= 1;
+}
+
 static void qbus_realize(BusState *bus, DeviceState *parent, const char *name)
 {
     const char *typename = object_get_typename(OBJECT(bus));
@@ -204,9 +255,14 @@ static char *default_bus_get_fw_dev_path(DeviceState *dev)
 static void bus_class_init(ObjectClass *class, void *data)
 {
     BusClass *bc = BUS_CLASS(class);
+    ResettableClass *rc = RESETTABLE_CLASS(class);
 
     class->unparent = bus_unparent;
     bc->get_fw_dev_path = default_bus_get_fw_dev_path;
+
+    rc->phases.init = bus_reset_init_phase;
+    rc->phases.hold = bus_reset_hold_phase;
+    rc->phases.exit = bus_reset_exit_phase;
 }
 
 static void qbus_finalize(Object *obj)
@@ -225,6 +281,10 @@ static const TypeInfo bus_info = {
     .instance_init = qbus_initfn,
     .instance_finalize = qbus_finalize,
     .class_init = bus_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_RESETTABLE },
+        { }
+    },
 };
 
 static void bus_register_types(void)
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index f9b6efe509..98d173f34f 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -37,6 +37,7 @@
 #include "hw/hotplug.h"
 #include "hw/boards.h"
 #include "hw/sysbus.h"
+#include "hw/resettable.h"
 
 bool qdev_hotplug = false;
 static bool qdev_hot_added = false;
@@ -254,6 +255,56 @@ HotplugHandler *qdev_get_hotplug_handler(DeviceState *dev)
     return hotplug_ctrl;
 }
 
+void qdev_reset(DeviceState *dev, bool cold)
+{
+    resettable_reset(OBJECT(dev), cold);
+}
+
+bool qdev_is_resetting(DeviceState *dev)
+{
+    return (dev->resetting != 0);
+}
+
+static void device_reset_init_phase(Object *obj, bool cold)
+{
+    DeviceState *dev = DEVICE(obj);
+    DeviceClass *dc = DEVICE_GET_CLASS(obj);
+    BusState *child;
+
+    QLIST_FOREACH(child, &dev->child_bus, sibling) {
+        resettable_init_phase(OBJECT(child), cold);
+    }
+
+    dev->resetting += 1;
+
+    if (dc->reset) {
+        dc->reset(dev);
+    }
+}
+
+static void device_reset_hold_phase(Object *obj)
+{
+    DeviceState *dev = DEVICE(obj);
+    BusState *child;
+
+    QLIST_FOREACH(child, &dev->child_bus, sibling) {
+        resettable_hold_phase(OBJECT(child));
+    }
+}
+
+static void device_reset_exit_phase(Object *obj)
+{
+    DeviceState *dev = DEVICE(obj);
+    BusState *child;
+
+    QLIST_FOREACH(child, &dev->child_bus, sibling) {
+        resettable_exit_phase(OBJECT(child));
+    }
+
+    assert(dev->resetting > 0);
+    dev->resetting -= 1;
+}
+
 static int qdev_reset_one(DeviceState *dev, void *opaque)
 {
     device_reset(dev);
@@ -954,6 +1005,7 @@ static void device_initfn(Object *obj)
 
     dev->instance_id_alias = -1;
     dev->realized = false;
+    dev->resetting = 0;
 
     object_property_add_bool(obj, "realized",
                              device_get_realized, device_set_realized, NULL);
@@ -1049,6 +1101,7 @@ static void device_unparent(Object *obj)
 static void device_class_init(ObjectClass *class, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(class);
+    ResettableClass *rc = RESETTABLE_CLASS(class);
 
     class->unparent = device_unparent;
 
@@ -1060,6 +1113,10 @@ static void device_class_init(ObjectClass *class, void 
*data)
      */
     dc->hotpluggable = true;
     dc->user_creatable = true;
+
+    rc->phases.init = device_reset_init_phase;
+    rc->phases.hold = device_reset_hold_phase;
+    rc->phases.exit = device_reset_exit_phase;
 }
 
 void device_class_set_parent_reset(DeviceClass *dc,
@@ -1117,6 +1174,10 @@ static const TypeInfo device_type_info = {
     .class_init = device_class_init,
     .abstract = true,
     .class_size = sizeof(DeviceClass),
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_RESETTABLE },
+        { }
+    },
 };
 
 static void qdev_register_types(void)
diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 33ed3b8dde..f4aa8dbaa2 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -131,6 +131,8 @@ struct NamedGPIOList {
 /**
  * DeviceState:
  * @realized: Indicates whether the device has been fully constructed.
+ * @resetting: Indicates whether the device is under reset. Also
+ * used to count how many times reset has been initiated on the device.
  *
  * This structure should not be accessed directly.  We declare it here
  * so that it can be embedded in individual device state structures.
@@ -152,6 +154,7 @@ struct DeviceState {
     int num_child_bus;
     int instance_id_alias;
     int alias_required_for_version;
+    uint32_t resetting;
 };
 
 struct DeviceListener {
@@ -198,6 +201,8 @@ typedef struct BusChild {
 /**
  * BusState:
  * @hotplug_handler: link to a hotplug handler associated with bus.
+ * @resetting: Indicates whether the device is under reset. Also
+ * used to count how many times reset has been initiated on the device.
  */
 struct BusState {
     Object obj;
@@ -209,6 +214,7 @@ struct BusState {
     int num_children;
     QTAILQ_HEAD(, BusChild) children;
     QLIST_ENTRY(BusState) sibling;
+    uint32_t resetting;
 };
 
 /**
@@ -378,6 +384,30 @@ int qdev_walk_children(DeviceState *dev,
                        qdev_walkerfn *post_devfn, qbus_walkerfn *post_busfn,
                        void *opaque);
 
+/**
+ * @qdev_reset:
+ * Reset the device @dev, @cold tell whether to do a cold or warm reset.
+ */
+void qdev_reset(DeviceState *dev, bool cold);
+
+/**
+ * @qbus_reset:
+ * Reset the bus @bus, @cold tell whether to do a cold or warm reset.
+ */
+void qbus_reset(BusState *bus, bool cold);
+
+/**
+ * @qdev_is_resetting:
+ * Tell whether the device @dev is currently under reset.
+ */
+bool qdev_is_resetting(DeviceState *dev);
+
+/**
+ * @qbus_is_resetting:
+ * Tell whether the bus @bus is currently under reset.
+ */
+bool qbus_is_resetting(BusState *bus);
+
 void qdev_reset_all(DeviceState *dev);
 void qdev_reset_all_fn(void *opaque);
 
-- 
2.21.0