From 614f731adb9cc86bd45ce749f597e68dbde253b1 Mon Sep 17 00:00:00 2001 From: Damien Hedde Date: Thu, 30 Jan 2020 16:02:04 +0000 Subject: hw/core/resettable: add support for changing parent MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Richard Henderson Reviewed-by: Philippe Mathieu-Daudé Tested-by: Philippe Mathieu-Daudé Message-id: 20200123132823.1117486-6-damien.hedde@greensocs.com Signed-off-by: Peter Maydell --- hw/core/resettable.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++-- hw/core/trace-events | 1 + include/hw/resettable.h | 16 +++++++++++++ 3 files changed, 77 insertions(+), 2 deletions(-) diff --git a/hw/core/resettable.c b/hw/core/resettable.c index 9133208487..6e0b0f492f 100644 --- a/hw/core/resettable.c +++ b/hw/core/resettable.c @@ -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, diff --git a/hw/core/trace-events b/hw/core/trace-events index 77d61cb66e..aecd8e160e 100644 --- a/hw/core/trace-events +++ b/hw/core/trace-events @@ -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" diff --git a/include/hw/resettable.h b/include/hw/resettable.h index c0b9fc6ad6..96073354fd 100644 --- a/include/hw/resettable.h +++ b/include/hw/resettable.h @@ -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: * -- cgit v1.2.3