diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index b3beab610da4..fc7ae05ce48a 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -704,6 +704,13 @@ int sclp_chp_deconfigure(struct chp_id chpid)
 	return do_chp_configure(SCLP_CMDW_DECONFIGURE_CHPATH | chpid.id << 8);
 }
 
+int arch_get_memory_phys_device(unsigned long start_pfn)
+{
+	if (!rzm)
+		return 0;
+	return PFN_PHYS(start_pfn) / rzm;
+}
+
 struct chp_info_sccb {
 	struct sccb_header header;
 	u8 recognized[SCLP_CHP_INFO_MASK_SIZE];