--- zzzz-none-000/linux-4.1.52/drivers/rtc/Makefile	2018-05-28 02:26:45.000000000 +0000
+++ bcm63-7530ax-731/linux-4.1.52/drivers/rtc/Makefile	2022-03-02 11:37:13.000000000 +0000
@@ -155,3 +155,35 @@
 obj-$(CONFIG_RTC_DRV_XGENE)	+= rtc-xgene.o
 obj-$(CONFIG_RTC_DRV_SIRFSOC)	+= rtc-sirfsoc.o
 obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o
+obj-$(CONFIG_RTC_DRV_AVM_REF_CLOCK)	+= rtc-avm.o
+
+ifeq ($(CONFIG_RTC_DRV_AVM_REF_CLOCK),m)
+CFLAGS_rtc-avm.o += -DRTC_AVM_DEVICE_COUNT=1 # -DRTC_AVM_DEBUG=1
+
+extra-y			 += install-S09-rtc
+
+$(obj)/S09-rtc: FORCE
+	$(Q)echo "  GEN     $@" >&2
+	$(Q)echo "#!/bin/sh" >$@
+	$(Q)echo "/sbin/modprobe rtc-avm" >>$@
+	$(Q)echo 'rtc_major=`grep rtc /proc/devices`' >>$@
+	$(Q)echo 'rtc_major=$${rtc_major%% rtc}' >>$@
+	$(Q)echo 'mknod /dev/rtc0 c $${rtc_major} 0' >>$@
+#	$(Q)echo 'mknod /dev/rtc1 c $${rtc_major} 1' >>$@
+
+ifeq ($(INSTALL_MOD_PATH),)
+export INSTALL_MOD_PATH = $(realpath $(srctree)/../../filesystem)
+$(info avmnet/common: Guessing INSTALL_MOD_PATH: $(INSTALL_MOD_PATH))
+endif
+
+$(INSTALL_MOD_PATH)/etc/init.d/S09-rtc: $(obj)/S09-rtc
+	$(Q)mkdir -p $(dir $@)
+	$(Q)if ! test -s $@ || ! cmp -s $< $@ ; then \
+		echo "  INSTALL $@ <- $<" >&2 ; \
+		cp $< $@ ; \
+	fi
+
+PHONY += install-S09-rtc
+$(obj)/install-S09-rtc: $(INSTALL_MOD_PATH)/etc/init.d/S09-rtc
+
+endif