drivers/pc80/rtc: Rename mc146818rtc_early.c -> _romcc.c

And don't link it. It's for ROMCC.

To make code happy that uses the ROMCC interface read_option(),
read_option_lowlevel() is ported to mc146818rtc.c along with
a message to use get_option() instead.

Change-Id: I54ea08de034766c8140b320075d36d5e811582fa
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/19663
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Tested-by: Raptor Engineering Automated Test Stand <noreply@raptorengineeringinc.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/drivers/pc80/rtc/Makefile.inc

@@ -1,9 +1,6 @@
 ifeq ($(CONFIG_ARCH_X86),y)
 
-romstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc_early.c
 romstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc.c
-
-ramstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc_early.c
 ramstage-$(CONFIG_DRIVERS_MC146818) += mc146818rtc.c
 
 ifeq ($(CONFIG_USE_OPTION_TABLE),y)

src/drivers/pc80/rtc/mc146818rtc.c

@@ -304,6 +304,17 @@ static enum cb_err set_cmos_value(unsigned long bit, unsigned long length,
 	return CB_SUCCESS;
 }
 
+unsigned int read_option_lowlevel(unsigned int start, unsigned int size,
+				  unsigned int def)
+{
+	printk(BIOS_NOTICE, "NOTICE: read_option() used to access CMOS "
+		"from non-ROMCC code, please use get_option() instead.\n");
+	if (IS_ENABLED(CONFIG_USE_OPTION_TABLE)) {
+		const unsigned char byte = cmos_read(start / 8);
+		return (byte >> (start & 7U)) & ((1U << size) - 1U);
+	}
+	return def;
+}
 
 enum cb_err set_option(const char *name, void *value)
 {