drm/nouveau/nvkm: add a replacement for nvkm_notify

This replaces the twisty, confusing, relationship between nvkm_event and
nvkm_notify with something much simpler, and less racey.  It also places
events in the object tree hierarchy, which will allow a heap of the code
tracking events across allocation/teardown/suspend to be removed.

This commit just adds the new interfaces, and passes the owning subdev to
the event constructor to enable debug-tracing in the new code.

v2:
- use ?: (lyude)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

21 files changed, 547 insertions, 29 deletions

diff --git a/drivers/gpu/drm/nouveau/include/nvif/class.h b/drivers/gpu/drm/nouveau/include/nvif/class.h
index 03f0f7c299f2..29448f77069b 100644
--- a/drivers/gpu/drm/nouveau/include/nvif/class.h
+++ b/drivers/gpu/drm/nouveau/include/nvif/class.h
@@ -32,6 +32,8 @@
 #define NVIF_CLASS_VMM_GM200                         /* ifb00d.h */  0x8000b00d
 #define NVIF_CLASS_VMM_GP100                         /* ifc00d.h */  0x8000c00d
 
+#define NVIF_CLASS_EVENT                             /* if000e.h */  0x8000000e
+
 #define NVIF_CLASS_DISP                              /* if0010.h */  0x80000010
 #define NVIF_CLASS_CONN                              /* if0011.h */  0x80000011
 #define NVIF_CLASS_OUTP                              /* if0012.h */  0x80000012
diff --git a/drivers/gpu/drm/nouveau/include/nvif/event.h b/drivers/gpu/drm/nouveau/include/nvif/event.h
index a6b1ee4f10ca..a510ba4ad487 100644
--- a/drivers/gpu/drm/nouveau/include/nvif/event.h
+++ b/drivers/gpu/drm/nouveau/include/nvif/event.h
@@ -1,6 +1,38 @@
 /* SPDX-License-Identifier: MIT */
 #ifndef __NVIF_EVENT_H__
 #define __NVIF_EVENT_H__
+#include <nvif/object.h>
+#include <nvif/if000e.h>
+struct nvif_event;
+
+#define NVIF_EVENT_KEEP 0
+#define NVIF_EVENT_DROP 1
+typedef int (*nvif_event_func)(struct nvif_event *, void *repv, u32 repc);
+
+struct nvif_event {
+	struct nvif_object object;
+	nvif_event_func func;
+};
+
+static inline bool
+nvif_event_constructed(struct nvif_event *event)
+{
+	return nvif_object_constructed(&event->object);
+}
+
+int nvif_event_ctor_(struct nvif_object *, const char *, u32, nvif_event_func, bool,
+		     struct nvif_event_v0 *, u32, bool, struct nvif_event *);
+
+static inline int
+nvif_event_ctor(struct nvif_object *parent, const char *name, u32 handle, nvif_event_func func,
+		bool wait, struct nvif_event_v0 *args, u32 argc, struct nvif_event *event)
+{
+	return nvif_event_ctor_(parent, name, handle, func, wait, args, argc, true, event);
+}
+
+void nvif_event_dtor(struct nvif_event *);
+int nvif_event_allow(struct nvif_event *);
+int nvif_event_block(struct nvif_event *);
 
 struct nvif_notify_req_v0 {
 	__u8  version;
diff --git a/drivers/gpu/drm/nouveau/include/nvif/if000e.h b/drivers/gpu/drm/nouveau/include/nvif/if000e.h
new file mode 100644
index 000000000000..90a936cb1766
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/include/nvif/if000e.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: MIT */
+#ifndef __NVIF_IF000E_H__
+#define __NVIF_IF000E_H__
+
+union nvif_event_args {
+	struct nvif_event_v0 {
+		__u8 version;
+		__u8 wait;
+		__u8 pad02[6];
+		__u8 data[];
+	} v0;
+};
+
+#define NVIF_EVENT_V0_ALLOW 0x00
+#define NVIF_EVENT_V0_BLOCK 0x01
+
+union nvif_event_allow_args {
+	struct nvif_event_allow_vn {
+	} vn;
+};
+
+union nvif_event_block_args {
+	struct nvif_event_block_vn {
+	} vn;
+};
+#endif
diff --git a/drivers/gpu/drm/nouveau/include/nvkm/core/client.h b/drivers/gpu/drm/nouveau/include/nvkm/core/client.h
index 2f86606e708c..2eb22aaed700 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/core/client.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/core/client.h
@@ -15,6 +15,7 @@ struct nvkm_client {
 
 	void *data;
 	int (*ntfy)(const void *, u32, const void *, u32);
+	int (*event)(u64 token, void *argv, u32 argc);
 
 	struct list_head umem;
 	spinlock_t lock;
@@ -23,6 +24,7 @@ struct nvkm_client {
 int  nvkm_client_new(const char *name, u64 device, const char *cfg,
 		     const char *dbg,
 		     int (*)(const void *, u32, const void *, u32),
+		     int (*)(u64, void *, u32),
 		     struct nvkm_client **);
 struct nvkm_client *nvkm_client_search(struct nvkm_client *, u64 handle);
 
diff --git a/drivers/gpu/drm/nouveau/include/nvkm/core/event.h b/drivers/gpu/drm/nouveau/include/nvkm/core/event.h
index a7a413f07a78..d6755a89f587 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/core/event.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/core/event.h
@@ -4,9 +4,12 @@
 #include <core/os.h>
 struct nvkm_notify;
 struct nvkm_object;
+struct nvkm_oclass;
+struct nvkm_uevent;
 
 struct nvkm_event {
 	const struct nvkm_event_func *func;
+	struct nvkm_subdev *subdev;
 
 	int types_nr;
 	int index_nr;
@@ -15,6 +18,8 @@ struct nvkm_event {
 	spinlock_t list_lock;
 	struct list_head list;
 	int *refs;
+
+	struct list_head ntfy;
 };
 
 struct nvkm_event_func {
@@ -25,11 +30,42 @@ struct nvkm_event_func {
 	void (*fini)(struct nvkm_event *, int type, int index);
 };
 
-int  nvkm_event_init(const struct nvkm_event_func *func, int types_nr,
+int  nvkm_event_init(const struct nvkm_event_func *func, struct nvkm_subdev *, int types_nr,
 		     int index_nr, struct nvkm_event *);
 void nvkm_event_fini(struct nvkm_event *);
 void nvkm_event_get(struct nvkm_event *, u32 types, int index);
 void nvkm_event_put(struct nvkm_event *, u32 types, int index);
 void nvkm_event_send(struct nvkm_event *, u32 types, int index,
 		     void *data, u32 size);
+
+#define NVKM_EVENT_KEEP 0
+#define NVKM_EVENT_DROP 1
+struct nvkm_event_ntfy;
+typedef int (*nvkm_event_func)(struct nvkm_event_ntfy *, u32 bits);
+
+struct nvkm_event_ntfy {
+	struct nvkm_event *event;
+	int id;
+	u32 bits;
+	bool wait;
+	nvkm_event_func func;
+
+	atomic_t allowed;
+	bool running;
+
+	struct list_head head;
+};
+
+void nvkm_event_ntfy(struct nvkm_event *, int id, u32 bits);
+bool nvkm_event_ntfy_valid(struct nvkm_event *, int id, u32 bits);
+void nvkm_event_ntfy_add(struct nvkm_event *, int id, u32 bits, bool wait, nvkm_event_func,
+			 struct nvkm_event_ntfy *);
+void nvkm_event_ntfy_del(struct nvkm_event_ntfy *);
+void nvkm_event_ntfy_allow(struct nvkm_event_ntfy *);
+void nvkm_event_ntfy_block(struct nvkm_event_ntfy *);
+
+typedef int (*nvkm_uevent_func)(struct nvkm_object *, u64 token, u32 bits);
+
+int nvkm_uevent_new(const struct nvkm_oclass *, void *argv, u32 argc, struct nvkm_object **);
+int nvkm_uevent_add(struct nvkm_uevent *, struct nvkm_event *, int id, u32 bits, nvkm_uevent_func);
 #endif
diff --git a/drivers/gpu/drm/nouveau/include/nvkm/core/object.h b/drivers/gpu/drm/nouveau/include/nvkm/core/object.h
index 7efcd5d2f2ff..ed1f66360782 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/core/object.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/core/object.h
@@ -4,6 +4,7 @@
 #include <core/oclass.h>
 struct nvkm_event;
 struct nvkm_gpuobj;
+struct nvkm_uevent;
 
 struct nvkm_object {
 	const struct nvkm_object_func *func;
@@ -43,6 +44,7 @@ struct nvkm_object_func {
 	int (*bind)(struct nvkm_object *, struct nvkm_gpuobj *, int align,
 		    struct nvkm_gpuobj **);
 	int (*sclass)(struct nvkm_object *, int index, struct nvkm_oclass *);
+	int (*uevent)(struct nvkm_object *, void *argv, u32 argc, struct nvkm_uevent *);
 };
 
 void nvkm_object_ctor(const struct nvkm_object_func *,
diff --git a/drivers/gpu/drm/nouveau/nouveau_nvif.c b/drivers/gpu/drm/nouveau/nouveau_nvif.c
index df0fe58ca3ab..be6d404a3459 100644
--- a/drivers/gpu/drm/nouveau/nouveau_nvif.c
+++ b/drivers/gpu/drm/nouveau/nouveau_nvif.c
@@ -72,10 +72,23 @@ nvkm_client_suspend(void *priv)
 }
 
 static int
+nvkm_client_event(u64 token, void *repv, u32 repc)
+{
+	struct nvif_object *object = (void *)(unsigned long)token;
+	struct nvif_event *event = container_of(object, typeof(*event), object);
+
+	if (event->func(event, repv, repc) == NVIF_EVENT_KEEP)
+		return NVKM_EVENT_KEEP;
+
+	return NVKM_EVENT_DROP;
+}
+
+static int
 nvkm_client_driver_init(const char *name, u64 device, const char *cfg,
 			const char *dbg, void **ppriv)
 {
-	return nvkm_client_new(name, device, cfg, dbg, nvif_notify, (struct nvkm_client **)ppriv);
+	return nvkm_client_new(name, device, cfg, dbg, nvif_notify, nvkm_client_event,
+			       (struct nvkm_client **)ppriv);
 }
 
 const struct nvif_driver
diff --git a/drivers/gpu/drm/nouveau/nvif/Kbuild b/drivers/gpu/drm/nouveau/nvif/Kbuild
index 6281291c70dc..7ce040ca2394 100644
--- a/drivers/gpu/drm/nouveau/nvif/Kbuild
+++ b/drivers/gpu/drm/nouveau/nvif/Kbuild
@@ -5,6 +5,7 @@ nvif-y += nvif/conn.o
 nvif-y += nvif/device.o
 nvif-y += nvif/disp.o
 nvif-y += nvif/driver.o
+nvif-y += nvif/event.o
 nvif-y += nvif/fifo.o
 nvif-y += nvif/head.o
 nvif-y += nvif/mem.o
diff --git a/drivers/gpu/drm/nouveau/nvif/event.c b/drivers/gpu/drm/nouveau/nvif/event.c
new file mode 100644
index 000000000000..61ff4d6eba9f
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/nvif/event.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2021 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <nvif/event.h>
+#include <nvif/printf.h>
+
+#include <nvif/class.h>
+#include <nvif/if000e.h>
+
+int
+nvif_event_block(struct nvif_event *event)
+{
+	if (nvif_event_constructed(event)) {
+		int ret = nvif_mthd(&event->object, NVIF_EVENT_V0_BLOCK, NULL, 0);
+		NVIF_ERRON(ret, &event->object, "[BLOCK]");
+		return ret;
+	}
+	return 0;
+}
+
+int
+nvif_event_allow(struct nvif_event *event)
+{
+	if (nvif_event_constructed(event)) {
+		int ret = nvif_mthd(&event->object, NVIF_EVENT_V0_ALLOW, NULL, 0);
+		NVIF_ERRON(ret, &event->object, "[ALLOW]");
+		return ret;
+	}
+	return 0;
+}
+
+void
+nvif_event_dtor(struct nvif_event *event)
+{
+	nvif_object_dtor(&event->object);
+}
+
+int
+nvif_event_ctor_(struct nvif_object *parent, const char *name, u32 handle, nvif_event_func func,
+		 bool wait, struct nvif_event_v0 *args, u32 argc, bool warn,
+		 struct nvif_event *event)
+{
+	struct nvif_event_v0 _args;
+	int ret;
+
+	if (!args) {
+		args = &_args;
+		argc = sizeof(_args);
+	}
+
+	args->version = 0;
+	args->wait = wait;
+
+	ret = nvif_object_ctor(parent, name ?: "nvifEvent", handle,
+			       NVIF_CLASS_EVENT, args, argc, &event->object);
+	NVIF_ERRON(ret && warn, parent, "[NEW EVENT wait:%d size:%zd]",
+		   args->wait, argc - sizeof(*args));
+	if (ret)
+		return ret;
+
+	event->func = func;
+	return 0;
+}
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/Kbuild b/drivers/gpu/drm/nouveau/nvkm/core/Kbuild
index 2b471ab585b4..216a3db821ee 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/Kbuild
+++ b/drivers/gpu/drm/nouveau/nvkm/core/Kbuild
@@ -14,3 +14,4 @@ nvkm-y += nvkm/core/oproxy.o
 nvkm-y += nvkm/core/option.o
 nvkm-y += nvkm/core/ramht.o
 nvkm-y += nvkm/core/subdev.o
+nvkm-y += nvkm/core/uevent.o
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/client.c b/drivers/gpu/drm/nouveau/nvkm/core/client.c
index 0c8c55c73b12..e1d978fbfe72 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/client.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/client.c
@@ -44,7 +44,7 @@ nvkm_uclient_new(const struct nvkm_oclass *oclass, void *argv, u32 argc,
 	if (!(ret = nvif_unpack(ret, &argv, &argc, args->v0, 0, 0, false))){
 		args->v0.name[sizeof(args->v0.name) - 1] = 0;
 		ret = nvkm_client_new(args->v0.name, args->v0.device, NULL,
-				      NULL, oclass->client->ntfy, &client);
+				      NULL, oclass->client->ntfy, oclass->client->event, &client);
 		if (ret)
 			return ret;
 	} else
@@ -286,7 +286,7 @@ int
 nvkm_client_new(const char *name, u64 device, const char *cfg,
 		const char *dbg,
 		int (*ntfy)(const void *, u32, const void *, u32),
-		struct nvkm_client **pclient)
+		int (*event)(u64, void *, u32), struct nvkm_client **pclient)
 {
 	struct nvkm_oclass oclass = { .base = nvkm_uclient_sclass };
 	struct nvkm_client *client;
@@ -301,6 +301,7 @@ nvkm_client_new(const char *name, u64 device, const char *cfg,
 	client->debug = nvkm_dbgopt(dbg, "CLIENT");
 	client->objroot = RB_ROOT;
 	client->ntfy = ntfy;
+	client->event = event;
 	INIT_LIST_HEAD(&client->umem);
 	spin_lock_init(&client->lock);
 	return 0;
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/event.c b/drivers/gpu/drm/nouveau/nvkm/core/event.c
index 006618d77aa4..ec508d1bbe1d 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/event.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/event.c
@@ -21,14 +21,19 @@
  */
 #include <core/event.h>
 #include <core/notify.h>
+#include <core/subdev.h>
 
 void
 nvkm_event_put(struct nvkm_event *event, u32 types, int index)
 {
 	assert_spin_locked(&event->refs_lock);
+
+	nvkm_trace(event->subdev, "event: decr %08x on %d\n", types, index);
+
 	while (types) {
 		int type = __ffs(types); types &= ~(1 << type);
 		if (--event->refs[index * event->types_nr + type] == 0) {
+			nvkm_trace(event->subdev, "event: blocking %d on %d\n", type, index);
 			if (event->func->fini)
 				event->func->fini(event, 1 << type, index);
 		}
@@ -39,18 +44,146 @@ void
 nvkm_event_get(struct nvkm_event *event, u32 types, int index)
 {
 	assert_spin_locked(&event->refs_lock);
+
+	nvkm_trace(event->subdev, "event: incr %08x on %d\n", types, index);
+
 	while (types) {
 		int type = __ffs(types); types &= ~(1 << type);
 		if (++event->refs[index * event->types_nr + type] == 1) {
+			nvkm_trace(event->subdev, "event: allowing %d on %d\n", type, index);
 			if (event->func->init)
 				event->func->init(event, 1 << type, index);
 		}
 	}
 }
 
+static void
+nvkm_event_ntfy_state(struct nvkm_event_ntfy *ntfy)
+{
+	struct nvkm_event *event = ntfy->event;
+	unsigned long flags;
+
+	nvkm_trace(event->subdev, "event: ntfy state changed\n");
+	spin_lock_irqsave(&event->refs_lock, flags);
+
+	if (atomic_read(&ntfy->allowed) != ntfy->running) {
+		if (ntfy->running) {
+			nvkm_event_put(ntfy->event, ntfy->bits, ntfy->id);
+			ntfy->running = false;
+		} else {
+			nvkm_event_get(ntfy->event, ntfy->bits, ntfy->id);
+			ntfy->running = true;
+		}
+	}
+
+	spin_unlock_irqrestore(&event->refs_lock, flags);
+}
+
+static void
+nvkm_event_ntfy_remove(struct nvkm_event_ntfy *ntfy)
+{
+	spin_lock_irq(&ntfy->event->list_lock);
+	list_del_init(&ntfy->head);
+	spin_unlock_irq(&ntfy->event->list_lock);
+}
+
+static void
+nvkm_event_ntfy_insert(struct nvkm_event_ntfy *ntfy)
+{
+	spin_lock_irq(&ntfy->event->list_lock);
+	list_add_tail(&ntfy->head, &ntfy->event->ntfy);
+	spin_unlock_irq(&ntfy->event->list_lock);
+}
+
+static void
+nvkm_event_ntfy_block_(struct nvkm_event_ntfy *ntfy, bool wait)
+{
+	struct nvkm_subdev *subdev = ntfy->event->subdev;
+
+	nvkm_trace(subdev, "event: ntfy block %08x on %d wait:%d\n", ntfy->bits, ntfy->id, wait);
+
+	if (atomic_xchg(&ntfy->allowed, 0) == 1) {
+		nvkm_event_ntfy_state(ntfy);
+		if (wait)
+			nvkm_event_ntfy_remove(ntfy);
+	}
+}
+
+void
+nvkm_event_ntfy_block(struct nvkm_event_ntfy *ntfy)
+{
+	if (ntfy->event)
+		nvkm_event_ntfy_block_(ntfy, ntfy->wait);
+}
+
+void
+nvkm_event_ntfy_allow(struct nvkm_event_ntfy *ntfy)
+{
+	nvkm_trace(ntfy->event->subdev, "event: ntfy allow %08x on %d\n", ntfy->bits, ntfy->id);
+
+	if (atomic_xchg(&ntfy->allowed, 1) == 0) {
+		nvkm_event_ntfy_state(ntfy);
+		if (ntfy->wait)
+			nvkm_event_ntfy_insert(ntfy);
+	}
+}
+
+void
+nvkm_event_ntfy_del(struct nvkm_event_ntfy *ntfy)
+{
+	struct nvkm_event *event = ntfy->event;
+
+	if (!event)
+		return;
+
+	nvkm_trace(event->subdev, "event: ntfy del %08x on %d\n", ntfy->bits, ntfy->id);
+
+	nvkm_event_ntfy_block_(ntfy, false);
+	nvkm_event_ntfy_remove(ntfy);
+	ntfy->event = NULL;
+}
+
+void
+nvkm_event_ntfy_add(struct nvkm_event *event, int id, u32 bits, bool wait, nvkm_event_func func,
+		    struct nvkm_event_ntfy *ntfy)
+{
+	nvkm_trace(event->subdev, "event: ntfy add %08x on %d wait:%d\n", id, bits, wait);
+
+	ntfy->event = event;
+	ntfy->id = id;
+	ntfy->bits = bits;
+	ntfy->wait = wait;
+	ntfy->func = func;
+	atomic_set(&ntfy->allowed, 0);
+	ntfy->running = false;
+	INIT_LIST_HEAD(&ntfy->head);
+	if (!ntfy->wait)
+		nvkm_event_ntfy_insert(ntfy);
+}
+
+bool
+nvkm_event_ntfy_valid(struct nvkm_event *event, int id, u32 bits)
+{
+	return true;
+}
+
+void
+nvkm_event_ntfy(struct nvkm_event *event, int id, u32 bits)
+{
+	struct nvkm_event_ntfy *ntfy, *ntmp;
+
+	nvkm_trace(event->subdev, "event: ntfy %08x on %d\n", bits, id);
+
+	list_for_each_entry_safe(ntfy, ntmp, &event->ntfy, head) {
+		if (ntfy->id == id && ntfy->bits & bits) {
+			if (atomic_read(&ntfy->allowed))
+				ntfy->func(ntfy, ntfy->bits & bits);
+		}
+	}
+}
+
 void
-nvkm_event_send(struct nvkm_event *event, u32 types, int index,
-		void *data, u32 size)
+nvkm_event_send(struct nvkm_event *event, u32 types, int index, void *data, u32 size)
 {
 	struct nvkm_notify *notify;
 	unsigned long flags;
@@ -59,6 +192,8 @@ nvkm_event_send(struct nvkm_event *event, u32 types, int index,
 		return;
 
 	spin_lock_irqsave(&event->list_lock, flags);
+	nvkm_event_ntfy(event, index, types);
+
 	list_for_each_entry(notify, &event->list, head) {
 		if (notify->index == index && (notify->types & types)) {
 			if (event->func->send) {
@@ -81,20 +216,20 @@ nvkm_event_fini(struct nvkm_event *event)
 }
 
 int
-nvkm_event_init(const struct nvkm_event_func *func, int types_nr, int index_nr,
-		struct nvkm_event *event)
+nvkm_event_init(const struct nvkm_event_func *func, struct nvkm_subdev *subdev,
+		int types_nr, int index_nr, struct nvkm_event *event)
 {
-	event->refs = kzalloc(array3_size(index_nr, types_nr,
-					  sizeof(*event->refs)),
-			      GFP_KERNEL);
+	event->refs = kzalloc(array3_size(index_nr, types_nr, sizeof(*event->refs)), GFP_KERNEL);
 	if (!event->refs)
 		return -ENOMEM;
 
 	event->func = func;
+	event->subdev = subdev;
 	event->types_nr = types_nr;
 	event->index_nr = index_nr;
 	spin_lock_init(&event->refs_lock);
 	spin_lock_init(&event->list_lock);
 	INIT_LIST_HEAD(&event->list);
+	INIT_LIST_HEAD(&event->ntfy);
 	return 0;
 }
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c b/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
index 45f920da89af..b42d0bf2c492 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/ioctl.c
@@ -47,6 +47,26 @@ nvkm_ioctl_nop(struct nvkm_client *client,
 	return ret;
 }
 
+#include <nvif/class.h>
+
+static int
+nvkm_ioctl_sclass_(struct nvkm_object *object, int index, struct nvkm_oclass *oclass)
+{
+	if ( object->func->uevent &&
+	    !object->func->uevent(object, NULL, 0, NULL) && index-- == 0) {
+		oclass->ctor = nvkm_uevent_new;
+		oclass->base.minver = 0;
+		oclass->base.maxver = 0;
+		oclass->base.oclass = NVIF_CLASS_EVENT;
+		return 0;
+	}
+
+	if (object->func->sclass)
+		return object->func->sclass(object, index, oclass);
+
+	return -ENOSYS;
+}
+
 static int
 nvkm_ioctl_sclass(struct nvkm_client *client,
 		  struct nvkm_object *object, void *data, u32 size)
@@ -64,8 +84,7 @@ nvkm_ioctl_sclass(struct nvkm_client *client,
 		if (size != args->v0.count * sizeof(args->v0.oclass[0]))
 			return -EINVAL;
 
-		while (object->func->sclass &&
-		       object->func->sclass(object, i, &oclass) >= 0) {
+		while (nvkm_ioctl_sclass_(object, i, &oclass) >= 0) {
 			if (i < args->v0.count) {
 				args->v0.oclass[i].oclass = oclass.base.oclass;
 				args->v0.oclass[i].minver = oclass.base.minver;
@@ -100,7 +119,7 @@ nvkm_ioctl_new(struct nvkm_client *client,
 	} else
 		return ret;
 
-	if (!parent->func->sclass) {
+	if (!parent->func->sclass && !parent->func->uevent) {
 		nvif_ioctl(parent, "cannot have children\n");
 		return -EINVAL;
 	}
@@ -113,7 +132,7 @@ nvkm_ioctl_new(struct nvkm_client *client,
 		oclass.object = args->v0.object;
 		oclass.client = client;
 		oclass.parent = parent;
-		ret = parent->func->sclass(parent, i++, &oclass);
+		ret = nvkm_ioctl_sclass_(parent, i++, &oclass);
 		if (ret)
 			return ret;
 	} while (oclass.base.oclass != args->v0.oclass);
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/oproxy.c b/drivers/gpu/drm/nouveau/nvkm/core/oproxy.c
index 16299837a296..3ffd4845d9e5 100644
--- a/drivers/gpu/drm/nouveau/nvkm/core/oproxy.c
+++ b/drivers/gpu/drm/nouveau/nvkm/core/oproxy.c
@@ -106,6 +106,18 @@ nvkm_oproxy_sclass(struct nvkm_object *object, int index,
 }
 
 static int
+nvkm_oproxy_uevent(struct nvkm_object *object, void *argv, u32 argc,
+		   struct nvkm_uevent *uevent)
+{
+	struct nvkm_oproxy *oproxy = nvkm_oproxy(object);
+
+	if (!oproxy->object->func->uevent)
+		return -ENOSYS;
+
+	return oproxy->object->func->uevent(oproxy->object, argv, argc, uevent);
+}
+
+static int
 nvkm_oproxy_fini(struct nvkm_object *object, bool suspend)
 {
 	struct nvkm_oproxy *oproxy = nvkm_oproxy(object);
@@ -188,6 +200,7 @@ nvkm_oproxy_func = {
 	.wr32 = nvkm_oproxy_wr32,
 	.bind = nvkm_oproxy_bind,
 	.sclass = nvkm_oproxy_sclass,
+	.uevent = nvkm_oproxy_uevent,
 };
 
 void
diff --git a/drivers/gpu/drm/nouveau/nvkm/core/uevent.c b/drivers/gpu/drm/nouveau/nvkm/core/uevent.c
new file mode 100644
index 000000000000..ba9d9edaec75
--- /dev/null
+++ b/drivers/gpu/drm/nouveau/nvkm/core/uevent.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright 2021 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+#define nvkm_uevent(p) container_of((p), struct nvkm_uevent, object)
+#include <core/event.h>
+#include <core/client.h>
+
+#include <nvif/if000e.h>
+
+struct nvkm_uevent {
+	struct nvkm_object object;
+	struct nvkm_object *parent;
+	nvkm_uevent_func func;
+	bool wait;
+
+	struct nvkm_event_ntfy ntfy;
+	atomic_t allowed;
+};
+
+static int
+nvkm_uevent_mthd_block(struct nvkm_uevent *uevent, union nvif_event_block_args *args, u32 argc)
+{
+	if (argc != sizeof(args->vn))
+		return -ENOSYS;
+
+	nvkm_event_ntfy_block(&uevent->ntfy);
+	atomic_set(&uevent->allowed, 0);
+	return 0;
+}
+
+static int
+nvkm_uevent_mthd_allow(struct nvkm_uevent *uevent, union nvif_event_allow_args *args, u32 argc)
+{
+	if (argc != sizeof(args->vn))
+		return -ENOSYS;
+
+	nvkm_event_ntfy_allow(&uevent->ntfy);
+	atomic_set(&uevent->allowed, 1);
+	return 0;
+}
+
+static int
+nvkm_uevent_mthd(struct nvkm_object *object, u32 mthd, void *argv, u32 argc)
+{
+	struct nvkm_uevent *uevent = nvkm_uevent(object);
+
+	switch (mthd) {
+	case NVIF_EVENT_V0_ALLOW: return nvkm_uevent_mthd_allow(uevent, argv, argc);
+	case NVIF_EVENT_V0_BLOCK: return nvkm_uevent_mthd_block(uevent, argv, argc);
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static int
+nvkm_uevent_fini(struct nvkm_object *object, bool suspend)
+{
+	struct nvkm_uevent *uevent = nvkm_uevent(object);
+
+	nvkm_event_ntfy_block(&uevent->ntfy);
+	return 0;
+}
+
+static int
+nvkm_uevent_init(struct nvkm_object *object)
+{
+	struct nvkm_uevent *uevent = nvkm_uevent(object);
+
+	if (atomic_read(&uevent->allowed))
+		nvkm_event_ntfy_allow(&uevent->ntfy);
+
+	return 0;
+}
+
+static void *
+nvkm_uevent_dtor(struct nvkm_object *object)
+{
+	struct nvkm_uevent *uevent = nvkm_uevent(object);
+
+	nvkm_event_ntfy_del(&uevent->ntfy);
+	return uevent;
+}
+
+static const struct nvkm_object_func
+nvkm_uevent = {
+	.dtor = nvkm_uevent_dtor,
+	.init = nvkm_uevent_init,
+	.fini = nvkm_uevent_fini,
+	.mthd = nvkm_uevent_mthd,
+};
+
+static int
+nvkm_uevent_ntfy(struct nvkm_event_ntfy *ntfy, u32 bits)
+{
+	struct nvkm_uevent *uevent = container_of(ntfy, typeof(*uevent), ntfy);
+	struct nvkm_client *client = uevent->object.client;
+
+	if (uevent->func)
+		return uevent->func(uevent->parent, uevent->object.token, bits);
+
+	return client->event(uevent->object.token, NULL, 0);
+}
+
+int
+nvkm_uevent_add(struct nvkm_uevent *uevent, struct nvkm_event *event, int id, u32 bits,
+		nvkm_uevent_func func)
+{
+	if (WARN_ON(uevent->func))
+		return -EBUSY;
+
+	nvkm_event_ntfy_add(event, id, bits, uevent->wait, nvkm_uevent_ntfy, &uevent->ntfy);
+	uevent->func = func;
+	return 0;
+}
+
+int
+nvkm_uevent_new(const struct nvkm_oclass *oclass, void *argv, u32 argc,
+		struct nvkm_object **pobject)
+{
+	struct nvkm_object *parent = oclass->parent;
+	struct nvkm_uevent *uevent;
+	union nvif_event_args *args = argv;
+
+	if (argc < sizeof(args->v0) || args->v0.version != 0)
+		return -ENOSYS;
+
+	if (!(uevent = kzalloc(sizeof(*uevent), GFP_KERNEL)))
+		return -ENOMEM;
+	*pobject = &uevent->object;
+
+	nvkm_object_ctor(&nvkm_uevent, oclass, &uevent->object);
+	uevent->parent = parent;
+	uevent->func = NULL;
+	uevent->wait = args->v0.wait;
+	uevent->ntfy.event = NULL;
+	return parent->func->uevent(parent, &args->v0.data, argc - sizeof(args->v0), uevent);
+}
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/base.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/base.c
index 65c99d948b68..55c97dc314e1 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/base.c
@@ -343,9 +343,7 @@ nvkm_disp_oneinit(struct nvkm_engine *engine)
 		/* Apparently we need to create a new one! */
 		ret = nvkm_conn_new(disp, i, &connE, &outp->conn);
 		if (ret) {
-			nvkm_error(&disp->engine.subdev,
-				   "failed to create outp %d conn: %d\n",
-				   outp->index, ret);
+			nvkm_error(subdev, "failed to create outp %d conn: %d\n", outp->index, ret);
 			nvkm_conn_del(&outp->conn);
 			list_del(&outp->head);
 			nvkm_outp_del(&outp);
@@ -355,7 +353,7 @@ nvkm_disp_oneinit(struct nvkm_engine *engine)
 		list_add_tail(&outp->conn->head, &disp->conns);
 	}
 
-	ret = nvkm_event_init(&nvkm_disp_hpd_func, 3, hpd, &disp->hpd);
+	ret = nvkm_event_init(&nvkm_disp_hpd_func, subdev, 3, hpd, &disp->hpd);
 	if (ret)
 		return ret;
 
@@ -382,7 +380,7 @@ nvkm_disp_oneinit(struct nvkm_engine *engine)
 	list_for_each_entry(head, &disp->heads, head)
 		i = max(i, head->id + 1);
 
-	return nvkm_event_init(&nvkm_disp_vblank_func, 1, i, &disp->vblank);
+	return nvkm_event_init(&nvkm_disp_vblank_func, subdev, 1, i, &disp->vblank);
 }
 
 static void *
@@ -473,5 +471,6 @@ nvkm_disp_new_(const struct nvkm_disp_func *func, struct nvkm_device *device,
 		mutex_init(&disp->super.mutex);
 	}
 
-	return nvkm_event_init(func->uevent, 1, ARRAY_SIZE(disp->chan), &disp->uevent);
+	return nvkm_event_init(func->uevent, &disp->engine.subdev, 1, ARRAY_SIZE(disp->chan),
+			       &disp->uevent);
 }
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/fifo/base.c b/drivers/gpu/drm/nouveau/nvkm/engine/fifo/base.c
index 58b8df75fc40..c94b2b9b9329 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/fifo/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/fifo/base.c
@@ -347,11 +347,11 @@ nvkm_fifo_ctor(const struct nvkm_fifo_func *func, struct nvkm_device *device,
 		return ret;
 
 	if (func->uevent_init) {
-		ret = nvkm_event_init(&nvkm_fifo_uevent_func, 1, 1,
+		ret = nvkm_event_init(&nvkm_fifo_uevent_func, &fifo->engine.subdev, 1, 1,
 				      &fifo->uevent);
 		if (ret)
 			return ret;
 	}
 
-	return nvkm_event_init(&nvkm_fifo_kevent_func, 1, nr, &fifo->kevent);
+	return nvkm_event_init(&nvkm_fifo_kevent_func, &fifo->engine.subdev, 1, nr, &fifo->kevent);
 }
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/sw/chan.c b/drivers/gpu/drm/nouveau/nvkm/engine/sw/chan.c
index f28967065639..d156f8676896 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/sw/chan.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/sw/chan.c
@@ -107,5 +107,5 @@ nvkm_sw_chan_ctor(const struct nvkm_sw_chan_func *func, struct nvkm_sw *sw,
 	list_add(&chan->head, &sw->chan);
 	spin_unlock_irqrestore(&sw->engine.lock, flags);
 
-	return nvkm_event_init(&nvkm_sw_chan_event, 1, 1, &chan->event);
+	return nvkm_event_init(&nvkm_sw_chan_event, &sw->engine.subdev, 1, 1, &chan->event);
 }
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/fault/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/fault/base.c
index fd54fa504efa..cc6fa1bb5034 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/fault/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/fault/base.c
@@ -130,8 +130,7 @@ nvkm_fault_oneinit(struct nvkm_subdev *subdev)
 		}
 	}
 
-	ret = nvkm_event_init(&nvkm_fault_ntfy, 1, fault->buffer_nr,
-			      &fault->event);
+	ret = nvkm_event_init(&nvkm_fault_ntfy, subdev, 1, fault->buffer_nr, &fault->event);
 	if (ret)
 		return ret;
 
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c
index 048bcc70c3f4..f2ccbcf219ca 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gpio/base.c
@@ -251,6 +251,5 @@ nvkm_gpio_new_(const struct nvkm_gpio_func *func, struct nvkm_device *device,
 	nvkm_subdev_ctor(&nvkm_gpio, device, type, inst, &gpio->subdev);
 	gpio->func = func;
 
-	return nvkm_event_init(&nvkm_gpio_intr_func, 2, func->lines,
-			       &gpio->event);
+	return nvkm_event_init(&nvkm_gpio_intr_func, &gpio->subdev, 2, func->lines, &gpio->event);
 }
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/base.c
index cb5cb533d91c..49a84ef146e9 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/i2c/base.c
@@ -427,5 +427,5 @@ nvkm_i2c_new_(const struct nvkm_i2c_func *func, struct nvkm_device *device,
 		}
 	}
 
-	return nvkm_event_init(&nvkm_i2c_intr_func, 4, i, &i2c->event);
+	return nvkm_event_init(&nvkm_i2c_intr_func, &i2c->subdev, 4, i, &i2c->event);
 }