hw/core/resettable: add support for changing parent

Add a function resettable_change_parent() to do the required
plumbing when changing the parent a of Resettable object.

We need to make sure that the reset state of the object remains
coherent with the reset state of the new parent.

We make the 2 following hypothesis:
+ when an object is put in a parent under reset, the object goes in
reset.
+ when an object is removed from a parent under reset, the object
leaves reset.

The added function avoids any glitch if both old and new parent are
already in reset.

Signed-off-by: Damien Hedde <damien.hedde@greensocs.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200123132823.1117486-6-damien.hedde@greensocs.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Damien Hedde 2020-01-30 16:02:04 +00:00 committed by Peter Maydell
parent c11256aa6f
commit 614f731adb
3 changed files with 77 additions and 2 deletions

View File

@ -28,12 +28,16 @@ static void resettable_phase_exit(Object *obj, void *opaque, ResetType type);
* enter_phase_in_progress:
* True if we are currently in reset enter phase.
*
* Note: This flag is only used to guarantee (using asserts) that the reset
* API is used correctly. We can use a global variable because we rely on the
* exit_phase_in_progress:
* count the number of exit phase we are in.
*
* Note: These flags are only used to guarantee (using asserts) that the reset
* API is used correctly. We can use global variables because we rely on the
* iothread mutex to ensure only one reset operation is in a progress at a
* given time.
*/
static bool enter_phase_in_progress;
static unsigned exit_phase_in_progress;
void resettable_reset(Object *obj, ResetType type)
{
@ -65,7 +69,9 @@ void resettable_release_reset(Object *obj, ResetType type)
trace_resettable_reset_release_begin(obj, type);
assert(!enter_phase_in_progress);
exit_phase_in_progress += 1;
resettable_phase_exit(obj, NULL, type);
exit_phase_in_progress -= 1;
trace_resettable_reset_release_end(obj);
}
@ -206,6 +212,58 @@ static void resettable_phase_exit(Object *obj, void *opaque, ResetType type)
trace_resettable_phase_exit_end(obj, obj_typename, s->count);
}
/*
* resettable_get_count:
* Get the count of the Resettable object @obj. Return 0 if @obj is NULL.
*/
static unsigned resettable_get_count(Object *obj)
{
if (obj) {
ResettableClass *rc = RESETTABLE_GET_CLASS(obj);
return rc->get_state(obj)->count;
}
return 0;
}
void resettable_change_parent(Object *obj, Object *newp, Object *oldp)
{
ResettableClass *rc = RESETTABLE_GET_CLASS(obj);
ResettableState *s = rc->get_state(obj);
unsigned newp_count = resettable_get_count(newp);
unsigned oldp_count = resettable_get_count(oldp);
/*
* Ensure we do not change parent when in enter or exit phase.
* During these phases, the reset subtree being updated is partly in reset
* and partly not in reset (it depends on the actual position in
* resettable_child_foreach()s). We are not able to tell in which part is a
* leaving or arriving device. Thus we cannot set the reset count of the
* moving device to the proper value.
*/
assert(!enter_phase_in_progress && !exit_phase_in_progress);
trace_resettable_change_parent(obj, oldp, oldp_count, newp, newp_count);
/*
* At most one of the two 'for' loops will be executed below
* in order to cope with the difference between the two counts.
*/
/* if newp is more reset than oldp */
for (unsigned i = oldp_count; i < newp_count; i++) {
resettable_assert_reset(obj, RESET_TYPE_COLD);
}
/*
* if obj is leaving a bus under reset, we need to ensure
* hold phase is not pending.
*/
if (oldp_count && s->hold_phase_pending) {
resettable_phase_hold(obj, NULL, RESET_TYPE_COLD);
}
/* if oldp is more reset than newp */
for (unsigned i = newp_count; i < oldp_count; i++) {
resettable_release_reset(obj, RESET_TYPE_COLD);
}
}
void resettable_class_set_parent_phases(ResettableClass *rc,
ResettableEnterPhase enter,
ResettableHoldPhase hold,

View File

@ -16,6 +16,7 @@ resettable_reset_assert_begin(void *obj, int cold) "obj=%p cold=%d"
resettable_reset_assert_end(void *obj) "obj=%p"
resettable_reset_release_begin(void *obj, int cold) "obj=%p cold=%d"
resettable_reset_release_end(void *obj) "obj=%p"
resettable_change_parent(void *obj, void *o, unsigned oc, void *n, unsigned nc) "obj=%p from=%p(%d) to=%p(%d)"
resettable_phase_enter_begin(void *obj, const char *objtype, unsigned count, int type) "obj=%p(%s) count=%d type=%d"
resettable_phase_enter_exec(void *obj, const char *objtype, int type, int has_method) "obj=%p(%s) type=%d method=%d"
resettable_phase_enter_end(void *obj, const char *objtype, unsigned count) "obj=%p(%s) count=%d"

View File

@ -194,6 +194,22 @@ void resettable_release_reset(Object *obj, ResetType type);
*/
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_class_set_parent_phases:
*