x86: unify mc146818rtc.h - prepare for sharing rtc code

Unify mc146818rtc.h by adding the rtc_cmos_read/write functions to
time_64.c. This is a preparatory patch to finaly share the rtc code,
which is unsurprisingly similar.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/time_64.c

@@ -69,6 +69,27 @@ unsigned long profile_pc(struct pt_regs *regs)
 }
 EXPORT_SYMBOL(profile_pc);
 
+/* Routines for accessing the CMOS RAM/RTC. */
+unsigned char rtc_cmos_read(unsigned char addr)
+{
+	unsigned char val;
+	lock_cmos_prefix(addr);
+	outb_p(addr, RTC_PORT(0));
+	val = inb_p(RTC_PORT(1));
+	lock_cmos_suffix(addr);
+	return val;
+}
+EXPORT_SYMBOL(rtc_cmos_read);
+
+void rtc_cmos_write(unsigned char val, unsigned char addr)
+{
+	lock_cmos_prefix(addr);
+	outb_p(addr, RTC_PORT(0));
+	outb_p(val, RTC_PORT(1));
+	lock_cmos_suffix(addr);
+}
+EXPORT_SYMBOL(rtc_cmos_write);
+
 /*
  * In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
  * ms after the second nowtime has started, because when nowtime is written