drm/nouveau/top: add function to lookup PRI address for devices

Will be using this in upcoming changes to avoid the need for entirely
new subdevs to deal with Turing register moves.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/include/nvkm/subdev/top.h

@@ -9,6 +9,7 @@ struct nvkm_top {
 	struct list_head device;
 };
 
+u32 nvkm_top_addr(struct nvkm_device *, enum nvkm_devidx);
 u32 nvkm_top_reset(struct nvkm_device *, enum nvkm_devidx);
 u32 nvkm_top_intr(struct nvkm_device *, u32 intr, u64 *subdevs);
 u32 nvkm_top_intr_mask(struct nvkm_device *, enum nvkm_devidx);

drivers/gpu/drm/nouveau/nvkm/subdev/top/base.c

@@ -40,6 +40,22 @@ nvkm_top_device_new(struct nvkm_top *top)
 	return info;
 }
 
+u32
+nvkm_top_addr(struct nvkm_device *device, enum nvkm_devidx index)
+{
+	struct nvkm_top *top = device->top;
+	struct nvkm_top_device *info;
+
+	if (top) {
+		list_for_each_entry(info, &top->device, head) {
+			if (info->index == index)
+				return info->addr;
+		}
+	}
+
+	return 0;
+}
+
 u32
 nvkm_top_reset(struct nvkm_device *device, enum nvkm_devidx index)
 {