drm/nouveau/flcn: move fetching of configuration until first use

We want to be able to register falcons with ACR during the constructor for
the subdev it belongs to, however, we may not have access to the falcon's
registers prior to DEVINIT.

Delay touching registers until the first time the falcon is acquired.

This may temporarily break secboot on non-production boards due to not
being able to determine whether the falcon is in debug or production mode,
the new ACR subdev will not have this issue, and it's not a use-case that's
terribly important for bisectability.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/engine/falcon.h

@@ -23,6 +23,8 @@ struct nvkm_falcon {
 
 	struct mutex mutex;
 	struct mutex dmem_mutex;
+	bool oneinit;
+
 	const struct nvkm_subdev *user;
 
 	u8 version;

drivers/gpu/drm/nouveau/nvkm/falcon/base.c

@@ -134,52 +134,13 @@ nvkm_falcon_clear_interrupt(struct nvkm_falcon *falcon, u32 mask)
 	return falcon->func->clear_interrupt(falcon, mask);
 }
 
-void
-nvkm_falcon_put(struct nvkm_falcon *falcon, const struct nvkm_subdev *user)
-{
-	if (unlikely(!falcon))
-		return;
-
-	mutex_lock(&falcon->mutex);
-	if (falcon->user == user) {
-		nvkm_debug(falcon->user, "released %s falcon\n", falcon->name);
-		falcon->user = NULL;
-	}
-	mutex_unlock(&falcon->mutex);
-}
-
-int
-nvkm_falcon_get(struct nvkm_falcon *falcon, const struct nvkm_subdev *user)
-{
-	mutex_lock(&falcon->mutex);
-	if (falcon->user) {
-		nvkm_error(user, "%s falcon already acquired by %s!\n",
-			   falcon->name, nvkm_subdev_name[falcon->user->index]);
-		mutex_unlock(&falcon->mutex);
-		return -EBUSY;
-	}
-
-	nvkm_debug(user, "acquired %s falcon\n", falcon->name);
-	falcon->user = user;
-	mutex_unlock(&falcon->mutex);
-	return 0;
-}
-
-void
-nvkm_falcon_ctor(const struct nvkm_falcon_func *func,
-		 struct nvkm_subdev *subdev, const char *name, u32 addr,
-		 struct nvkm_falcon *falcon)
+static int
+nvkm_falcon_oneinit(struct nvkm_falcon *falcon)
 {
+	const struct nvkm_subdev *subdev = falcon->owner;
 	u32 debug_reg;
 	u32 reg;
 
-	falcon->func = func;
-	falcon->owner = subdev;
-	falcon->name = name;
-	falcon->addr = addr;
-	mutex_init(&falcon->mutex);
-	mutex_init(&falcon->dmem_mutex);
-
 	reg = nvkm_falcon_rd32(falcon, 0x12c);
 	falcon->version = reg & 0xf;
 	falcon->secret = (reg >> 4) & 0x3;
@@ -218,6 +179,56 @@ nvkm_falcon_ctor(const struct nvkm_falcon_func *func,
 		u32 val = nvkm_falcon_rd32(falcon, debug_reg);
 		falcon->debug = (val >> 20) & 0x1;
 	}
+
+	return 0;
+}
+
+void
+nvkm_falcon_put(struct nvkm_falcon *falcon, const struct nvkm_subdev *user)
+{
+	if (unlikely(!falcon))
+		return;
+
+	mutex_lock(&falcon->mutex);
+	if (falcon->user == user) {
+		nvkm_debug(falcon->user, "released %s falcon\n", falcon->name);
+		falcon->user = NULL;
+	}
+	mutex_unlock(&falcon->mutex);
+}
+
+int
+nvkm_falcon_get(struct nvkm_falcon *falcon, const struct nvkm_subdev *user)
+{
+	int ret = 0;
+
+	mutex_lock(&falcon->mutex);
+	if (falcon->user) {
+		nvkm_error(user, "%s falcon already acquired by %s!\n",
+			   falcon->name, nvkm_subdev_name[falcon->user->index]);
+		mutex_unlock(&falcon->mutex);
+		return -EBUSY;
+	}
+
+	nvkm_debug(user, "acquired %s falcon\n", falcon->name);
+	if (!falcon->oneinit)
+		ret = nvkm_falcon_oneinit(falcon);
+	falcon->user = user;
+	mutex_unlock(&falcon->mutex);
+	return ret;
+}
+
+void
+nvkm_falcon_ctor(const struct nvkm_falcon_func *func,
+		 struct nvkm_subdev *subdev, const char *name, u32 addr,
+		 struct nvkm_falcon *falcon)
+{
+	falcon->func = func;
+	falcon->owner = subdev;
+	falcon->name = name;
+	falcon->addr = addr;
+	mutex_init(&falcon->mutex);
+	mutex_init(&falcon->dmem_mutex);
 }
 
 void