Commit 5cc56cc6 authored by Peter Maydell's avatar Peter Maydell
Browse files

qdev: support properties which don't set a default value 



In some situations it's useful to have a qdev property which doesn't
automatically set its default value when qdev_property_add_static is
called (for instance when the default value is not constant).

Support this by adding a flag to the Property struct indicating
whether to set the default value.  This replaces the existing test
for whether the PropertyInfo set_default_value function pointer is
NULL, and we set the .set_default field to true for all those cases
of struct Property which use a PropertyInfo with a non-NULL
set_default_value, so behaviour remains the same as before.

This gives us the semantics of:
 * if .set_default is true, then .info->set_default_value must
   be not NULL, and .defval is used as the the default value of
   the property
 * otherwise, the property system does not set any default, and
   the field will retain whatever initial value it was given by
   the device's .instance_init method

We define two new macros DEFINE_PROP_SIGNED_NODEFAULT and
DEFINE_PROP_UNSIGNED_NODEFAULT, to cover the most plausible use cases
of wanting to set an integer property with no default value.

Suggested-by: default avatarMarkus Armbruster <armbru@redhat.com>
Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: default avatarMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: default avatarMarkus Armbruster <armbru@redhat.com>
Message-id: 1499788408-10096-3-git-send-email-peter.maydell@linaro.org
parent d9a7b125

hw/core/qdev.c

+1 −1
Original line number Diff line number Diff line
@@ -800,7 +800,7 @@ void qdev_property_add_static(DeviceState *dev, Property *prop, 
                                    prop->info->description,

                                    &error_abort);



    if (prop->info->set_default_value) {

    if (prop->set_default) {

        prop->info->set_default_value(obj, prop);

    }

}

include/hw/qdev-core.h

+10 −0
Original line number Diff line number Diff line
@@ -221,11 +221,21 @@ struct BusState { 
    QLIST_ENTRY(BusState) sibling;

};



/**

 * Property:

 * @set_default: true if the default value should be set from @defval,

 *    in which case @info->set_default_value must not be NULL

 *    (if false then no default value is set by the property system

 *     and the field retains whatever value it was given by instance_init).

 * @defval: default value for the property. This is used only if @set_default

 *     is true.

 */

struct Property {

    const char   *name;

    const PropertyInfo *info;

    ptrdiff_t    offset;

    uint8_t      bitnr;

    bool         set_default;

    union {

        int64_t i;

        uint64_t u;

include/hw/qdev-properties.h

+20 −0
Original line number Diff line number Diff line
@@ -44,15 +44,24 @@ extern const PropertyInfo qdev_prop_link; 
        .info      = &(_prop),                                          \

        .offset    = offsetof(_state, _field)                           \

            + type_check(_type,typeof_field(_state, _field)),           \

        .set_default = true,                                            \

        .defval.i  = (_type)_defval,                                    \

        }



#define DEFINE_PROP_SIGNED_NODEFAULT(_name, _state, _field, _prop, _type) { \

        .name      = (_name),                                           \

        .info      = &(_prop),                                          \

        .offset    = offsetof(_state, _field)                           \

            + type_check(_type, typeof_field(_state, _field)),          \

        }



#define DEFINE_PROP_BIT(_name, _state, _field, _bit, _defval) {  \

        .name      = (_name),                                    \

        .info      = &(qdev_prop_bit),                           \

        .bitnr    = (_bit),                                      \

        .offset    = offsetof(_state, _field)                    \

            + type_check(uint32_t,typeof_field(_state, _field)), \

        .set_default = true,                                     \

        .defval.u  = (bool)_defval,                              \

        }
@@ -61,15 +70,24 @@ extern const PropertyInfo qdev_prop_link; 
        .info      = &(_prop),                                          \

        .offset    = offsetof(_state, _field)                           \

            + type_check(_type, typeof_field(_state, _field)),          \

        .set_default = true,                                            \

        .defval.u  = (_type)_defval,                                    \

        }



#define DEFINE_PROP_UNSIGNED_NODEFAULT(_name, _state, _field, _prop, _type) { \

        .name      = (_name),                                           \

        .info      = &(_prop),                                          \

        .offset    = offsetof(_state, _field)                           \

            + type_check(_type, typeof_field(_state, _field)),          \

        }



#define DEFINE_PROP_BIT64(_name, _state, _field, _bit, _defval) {       \

        .name      = (_name),                                           \

        .info      = &(qdev_prop_bit64),                                \

        .bitnr    = (_bit),                                             \

        .offset    = offsetof(_state, _field)                           \

            + type_check(uint64_t, typeof_field(_state, _field)),       \

        .set_default = true,                                            \

        .defval.u  = (bool)_defval,                                     \

        }
@@ -78,6 +96,7 @@ extern const PropertyInfo qdev_prop_link; 
        .info      = &(qdev_prop_bool),                          \

        .offset    = offsetof(_state, _field)                    \

            + type_check(bool, typeof_field(_state, _field)),    \

        .set_default = true,                                     \

        .defval.u    = (bool)_defval,                            \

        }
@@ -111,6 +130,7 @@ extern const PropertyInfo qdev_prop_link; 
                          _arrayfield, _arrayprop, _arraytype) {        \

        .name = (PROP_ARRAY_LEN_PREFIX _name),                          \

        .info = &(qdev_prop_arraylen),                                  \

        .set_default = true,                                            \

        .defval.u = 0,                                                  \

        .offset = offsetof(_state, _field)                              \

            + type_check(uint32_t, typeof_field(_state, _field)),       \