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+/*
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+ * linux/arch/alpha/kernel/rtc.c
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+ *
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+ * Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds
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+ *
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+ * This file contains date handling.
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+ */
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+#include <linux/errno.h>
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+#include <linux/init.h>
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+#include <linux/kernel.h>
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+#include <linux/param.h>
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+#include <linux/string.h>
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+#include <linux/mc146818rtc.h>
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+#include <linux/bcd.h>
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+#include <linux/rtc.h>
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+#include <linux/platform_device.h>
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+
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+#include <asm/rtc.h>
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+
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+#include "proto.h"
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+
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+
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+/*
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+ * Support for the RTC device.
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+ *
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+ * We don't want to use the rtc-cmos driver, because we don't want to support
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+ * alarms, as that would be indistinguishable from timer interrupts.
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+ *
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+ * Further, generic code is really, really tied to a 1900 epoch. This is
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+ * true in __get_rtc_time as well as the users of struct rtc_time e.g.
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+ * rtc_tm_to_time. Thankfully all of the other epochs in use are later
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+ * than 1900, and so it's easy to adjust.
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+ */
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+
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+static unsigned long rtc_epoch;
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+
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+static int __init
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+specifiy_epoch(char *str)
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+{
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+ unsigned long epoch = simple_strtoul(str, NULL, 0);
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+ if (epoch < 1900)
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+ printk("Ignoring invalid user specified epoch %lu\n", epoch);
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+ else
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+ rtc_epoch = epoch;
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+ return 1;
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+}
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+__setup("epoch=", specifiy_epoch);
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+
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+static void __init
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+init_rtc_epoch(void)
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+{
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+ int epoch, year, ctrl;
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+
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+ if (rtc_epoch != 0) {
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+ /* The epoch was specified on the command-line. */
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+ return;
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+ }
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+
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+ /* Detect the epoch in use on this computer. */
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+ ctrl = CMOS_READ(RTC_CONTROL);
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+ year = CMOS_READ(RTC_YEAR);
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+ if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
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+ year = bcd2bin(year);
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+
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+ /* PC-like is standard; used for year >= 70 */
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+ epoch = 1900;
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+ if (year < 20) {
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+ epoch = 2000;
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+ } else if (year >= 20 && year < 48) {
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+ /* NT epoch */
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+ epoch = 1980;
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+ } else if (year >= 48 && year < 70) {
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+ /* Digital UNIX epoch */
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+ epoch = 1952;
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+ }
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+ rtc_epoch = epoch;
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+
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+ printk(KERN_INFO "Using epoch %d for rtc year %d\n", epoch, year);
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+}
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+
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+static int
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+alpha_rtc_read_time(struct device *dev, struct rtc_time *tm)
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+{
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+ __get_rtc_time(tm);
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+
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+ /* Adjust for non-default epochs. It's easier to depend on the
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+ generic __get_rtc_time and adjust the epoch here than create
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+ a copy of __get_rtc_time with the edits we need. */
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+ if (rtc_epoch != 1900) {
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+ int year = tm->tm_year;
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+ /* Undo the century adjustment made in __get_rtc_time. */
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+ if (year >= 100)
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+ year -= 100;
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+ year += rtc_epoch - 1900;
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+ /* Redo the century adjustment with the epoch in place. */
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+ if (year <= 69)
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+ year += 100;
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+ tm->tm_year = year;
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+ }
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+
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+ return rtc_valid_tm(tm);
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+}
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+
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+static int
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+alpha_rtc_set_time(struct device *dev, struct rtc_time *tm)
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+{
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+ struct rtc_time xtm;
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+
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+ if (rtc_epoch != 1900) {
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+ xtm = *tm;
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+ xtm.tm_year -= rtc_epoch - 1900;
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+ tm = &xtm;
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+ }
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+
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+ return __set_rtc_time(tm);
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+}
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+
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+static int
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+alpha_rtc_set_mmss(struct device *dev, unsigned long nowtime)
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+{
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+ int retval = 0;
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+ int real_seconds, real_minutes, cmos_minutes;
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+ unsigned char save_control, save_freq_select;
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+
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+ /* Note: This code only updates minutes and seconds. Comments
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+ indicate this was to avoid messing with unknown time zones,
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+ and with the epoch nonsense described above. In order for
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+ this to work, the existing clock cannot be off by more than
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+ 15 minutes.
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+
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+ ??? This choice is may be out of date. The x86 port does
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+ not have problems with timezones, and the epoch processing has
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+ now been fixed in alpha_set_rtc_time.
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+
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+ In either case, one can always force a full rtc update with
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+ the userland hwclock program, so surely 15 minute accuracy
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+ is no real burden. */
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+
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+ /* In order to set the CMOS clock precisely, we have to be called
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+ 500 ms after the second nowtime has started, because when
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+ nowtime is written into the registers of the CMOS clock, it will
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+ jump to the next second precisely 500 ms later. Check the Motorola
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+ MC146818A or Dallas DS12887 data sheet for details. */
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+
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+ /* irq are locally disabled here */
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+ spin_lock(&rtc_lock);
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+ /* Tell the clock it's being set */
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+ save_control = CMOS_READ(RTC_CONTROL);
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+ CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
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+
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+ /* Stop and reset prescaler */
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+ save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
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+ CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
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+
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+ cmos_minutes = CMOS_READ(RTC_MINUTES);
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+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
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+ cmos_minutes = bcd2bin(cmos_minutes);
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+
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+ real_seconds = nowtime % 60;
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+ real_minutes = nowtime / 60;
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+ if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) {
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+ /* correct for half hour time zone */
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+ real_minutes += 30;
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+ }
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+ real_minutes %= 60;
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+
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+ if (abs(real_minutes - cmos_minutes) < 30) {
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+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
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+ real_seconds = bin2bcd(real_seconds);
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+ real_minutes = bin2bcd(real_minutes);
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+ }
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+ CMOS_WRITE(real_seconds,RTC_SECONDS);
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+ CMOS_WRITE(real_minutes,RTC_MINUTES);
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+ } else {
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+ printk_once(KERN_NOTICE
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+ "set_rtc_mmss: can't update from %d to %d\n",
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+ cmos_minutes, real_minutes);
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+ retval = -1;
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+ }
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+
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+ /* The following flags have to be released exactly in this order,
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+ * otherwise the DS12887 (popular MC146818A clone with integrated
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+ * battery and quartz) will not reset the oscillator and will not
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+ * update precisely 500 ms later. You won't find this mentioned in
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+ * the Dallas Semiconductor data sheets, but who believes data
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+ * sheets anyway ... -- Markus Kuhn
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+ */
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+ CMOS_WRITE(save_control, RTC_CONTROL);
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+ CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
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+ spin_unlock(&rtc_lock);
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+
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+ return retval;
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+}
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+
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+static int
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+alpha_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
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+{
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+ switch (cmd) {
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+ case RTC_EPOCH_READ:
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+ return put_user(rtc_epoch, (unsigned long __user *)arg);
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+ case RTC_EPOCH_SET:
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+ if (arg < 1900)
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+ return -EINVAL;
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+ rtc_epoch = arg;
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+ return 0;
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+ default:
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+ return -ENOIOCTLCMD;
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+ }
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+}
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+
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+static const struct rtc_class_ops alpha_rtc_ops = {
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+ .read_time = alpha_rtc_read_time,
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+ .set_time = alpha_rtc_set_time,
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+ .set_mmss = alpha_rtc_set_mmss,
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+ .ioctl = alpha_rtc_ioctl,
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+};
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+
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+/*
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+ * Similarly, except do the actual CMOS access on the boot cpu only.
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+ * This requires marshalling the data across an interprocessor call.
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+ */
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+
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+#if defined(CONFIG_SMP) && \
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+ (defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_MARVEL))
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+# define HAVE_REMOTE_RTC 1
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+
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+union remote_data {
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+ struct rtc_time *tm;
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+ unsigned long now;
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+ long retval;
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+};
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+
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+static void
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+do_remote_read(void *data)
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+{
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+ union remote_data *x = data;
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+ x->retval = alpha_rtc_read_time(NULL, x->tm);
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+}
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+
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+static int
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+remote_read_time(struct device *dev, struct rtc_time *tm)
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+{
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+ union remote_data x;
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+ if (smp_processor_id() != boot_cpuid) {
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+ x.tm = tm;
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+ smp_call_function_single(boot_cpuid, do_remote_read, &x, 1);
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+ return x.retval;
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+ }
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+ return alpha_rtc_read_time(NULL, tm);
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+}
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+
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+static void
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+do_remote_set(void *data)
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+{
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+ union remote_data *x = data;
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+ x->retval = alpha_rtc_set_time(NULL, x->tm);
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+}
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+
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+static int
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+remote_set_time(struct device *dev, struct rtc_time *tm)
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+{
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+ union remote_data x;
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+ if (smp_processor_id() != boot_cpuid) {
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+ x.tm = tm;
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+ smp_call_function_single(boot_cpuid, do_remote_set, &x, 1);
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+ return x.retval;
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+ }
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+ return alpha_rtc_set_time(NULL, tm);
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+}
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+
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+static void
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+do_remote_mmss(void *data)
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+{
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+ union remote_data *x = data;
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+ x->retval = alpha_rtc_set_mmss(NULL, x->now);
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+}
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+
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+static int
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+remote_set_mmss(struct device *dev, unsigned long now)
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+{
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+ union remote_data x;
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+ if (smp_processor_id() != boot_cpuid) {
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+ x.now = now;
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+ smp_call_function_single(boot_cpuid, do_remote_mmss, &x, 1);
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+ return x.retval;
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+ }
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+ return alpha_rtc_set_mmss(NULL, now);
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+}
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+
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+static const struct rtc_class_ops remote_rtc_ops = {
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+ .read_time = remote_read_time,
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+ .set_time = remote_set_time,
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+ .set_mmss = remote_set_mmss,
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+ .ioctl = alpha_rtc_ioctl,
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+};
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+#endif
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+
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+static int __init
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+alpha_rtc_init(void)
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+{
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+ const struct rtc_class_ops *ops;
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+ struct platform_device *pdev;
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+ struct rtc_device *rtc;
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+ const char *name;
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+
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+ init_rtc_epoch();
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+ name = "rtc-alpha";
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+ ops = &alpha_rtc_ops;
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+
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+#ifdef HAVE_REMOTE_RTC
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+ if (alpha_mv.rtc_boot_cpu_only)
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+ ops = &remote_rtc_ops;
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+#endif
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+
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+ pdev = platform_device_register_simple(name, -1, NULL, 0);
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+ rtc = devm_rtc_device_register(&pdev->dev, name, ops, THIS_MODULE);
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+ if (IS_ERR(rtc))
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+ return PTR_ERR(rtc);
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+
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+ platform_set_drvdata(pdev, rtc);
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+ return 0;
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+}
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+device_initcall(alpha_rtc_init);
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Richard Henderson