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>
diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/top.h b/drivers/gpu/drm/nouveau/include/nvkm/subdev/top.h
index f7d3eb6..2904e67d 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/top.h
+++ b/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);
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/top/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/top/base.c
index 67ada1d..cce6e4e 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/top/base.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/top/base.c
@@ -41,6 +41,22 @@ nvkm_top_device_new(struct nvkm_top *top)
 }
 
 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)
 {
 	struct nvkm_top *top = device->top;