drm/nouveau/fifo: expose function to read engine ctxsw status

Needed to support Ampere differences in gr/gf100-:
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

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

@@ -75,6 +75,7 @@ struct nvkm_fifo {
 void nvkm_fifo_fault(struct nvkm_fifo *, struct nvkm_fault_data *);
 void nvkm_fifo_pause(struct nvkm_fifo *, unsigned long *);
 void nvkm_fifo_start(struct nvkm_fifo *, unsigned long *);
+bool nvkm_fifo_ctxsw_in_progress(struct nvkm_engine *);
 
 int nv04_fifo_new(struct nvkm_device *, enum nvkm_subdev_type, int inst, struct nvkm_fifo **);
 int nv10_fifo_new(struct nvkm_device *, enum nvkm_subdev_type, int inst, struct nvkm_fifo **);

drivers/gpu/drm/nouveau/nvkm/engine/fifo/base.c

@@ -35,6 +35,22 @@
 #include <nvif/cl0080.h>
 #include <nvif/unpack.h>
 
+bool
+nvkm_fifo_ctxsw_in_progress(struct nvkm_engine *engine)
+{
+	struct nvkm_runl *runl;
+	struct nvkm_engn *engn;
+
+	nvkm_runl_foreach(runl, engine->subdev.device->fifo) {
+		nvkm_runl_foreach_engn(engn, runl) {
+			if (engn->engine == engine)
+				return engn->func->chsw ? engn->func->chsw(engn) : false;
+		}
+	}
+
+	return false;
+}
+
 void
 nvkm_fifo_pause(struct nvkm_fifo *fifo, unsigned long *flags)
 {

drivers/gpu/drm/nouveau/nvkm/engine/gr/gf100.c

@@ -1003,7 +1003,7 @@ gf100_gr_wait_idle(struct gf100_gr *gr)
 		nvkm_rd32(device, 0x400700);
 
 		gr_enabled = nvkm_rd32(device, 0x200) & 0x1000;
-		ctxsw_active = nvkm_rd32(device, 0x2640) & 0x8000;
+		ctxsw_active = nvkm_fifo_ctxsw_in_progress(&gr->base.engine);
 		gr_busy = nvkm_rd32(device, 0x40060c) & 0x1;
 
 		if (!gr_enabled || (!gr_busy && !ctxsw_active))