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// SPDX-License-Identifier: GPL-2.0
/*
* linux/arch/alpha/kernel/rtc.c
*
* Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds
*
* This file contains date handling.
*/
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mc146818rtc.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>
#include "proto.h"
/*
* Support for the RTC device.
*
* We don't want to use the rtc-cmos driver, because we don't want to support
* alarms, as that would be indistinguishable from timer interrupts.
*
* Further, generic code is really, really tied to a 1900 epoch. This is
* true in __get_rtc_time as well as the users of struct rtc_time e.g.
* rtc_tm_to_time. Thankfully all of the other epochs in use are later
* than 1900, and so it's easy to adjust.
*/
static unsigned long rtc_epoch;
static int __init
specifiy_epoch(char *str)
{
unsigned long epoch = simple_strtoul(str, NULL, 0);
if (epoch < 1900)
printk("Ignoring invalid user specified epoch %lu\n", epoch);
else
rtc_epoch = epoch;
return 1;
}
__setup("epoch=", specifiy_epoch);
static void __init
init_rtc_epoch(void)
{
int epoch, year, ctrl;
if (rtc_epoch != 0) {
/* The epoch was specified on the command-line. */
return;
}
/* Detect the epoch in use on this computer. */
ctrl = CMOS_READ(RTC_CONTROL);
year = CMOS_READ(RTC_YEAR);
if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
year = bcd2bin(year);
/* PC-like is standard; used for year >= 70 */
epoch = 1900;
if (year < 20) {
epoch = 2000;
} else if (year >= 20 && year < 48) {
/* NT epoch */
epoch = 1980;
} else if (year >= 48 && year < 70) {
/* Digital UNIX epoch */
epoch = 1952;
}
rtc_epoch = epoch;
printk(KERN_INFO "Using epoch %d for rtc year %d\n", epoch, year);
}
static int
alpha_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
int ret = mc146818_get_time(tm);
if (ret < 0) {
dev_err_ratelimited(dev, "unable to read current time\n");
return ret;
}
/* Adjust for non-default epochs. It's easier to depend on the
generic __get_rtc_time and adjust the epoch here than create
a copy of __get_rtc_time with the edits we need. */
if (rtc_epoch != 1900) {
int year = tm->tm_year;
/* Undo the century adjustment made in __get_rtc_time. */
if (year >= 100)
year -= 100;
year += rtc_epoch - 1900;
/* Redo the century adjustment with the epoch in place. */
if (year <= 69)
year += 100;
tm->tm_year = year;
}
return 0;
}
static int
alpha_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rtc_time xtm;
if (rtc_epoch != 1900) {
xtm = *tm;
xtm.tm_year -= rtc_epoch - 1900;
tm = &xtm;
}
return mc146818_set_time(tm);
}
static int
alpha_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
{
switch (cmd) {
case RTC_EPOCH_READ:
return put_user(rtc_epoch, (unsigned long __user *)arg);
case RTC_EPOCH_SET:
if (arg < 1900)
return -EINVAL;
rtc_epoch = arg;
return 0;
default:
return -ENOIOCTLCMD;
}
}
static const struct rtc_class_ops alpha_rtc_ops = {
.read_time = alpha_rtc_read_time,
.set_time = alpha_rtc_set_time,
.ioctl = alpha_rtc_ioctl,
};
/*
* Similarly, except do the actual CMOS access on the boot cpu only.
* This requires marshalling the data across an interprocessor call.
*/
#if defined(CONFIG_SMP) && \
(defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_MARVEL))
# define HAVE_REMOTE_RTC 1
union remote_data {
struct rtc_time *tm;
long retval;
};
static void
do_remote_read(void *data)
{
union remote_data *x = data;
x->retval = alpha_rtc_read_time(NULL, x->tm);
}
static int
remote_read_time(struct device *dev, struct rtc_time *tm)
{
union remote_data x;
if (smp_processor_id() != boot_cpuid) {
x.tm = tm;
smp_call_function_single(boot_cpuid, do_remote_read, &x, 1);
return x.retval;
}
return alpha_rtc_read_time(NULL, tm);
}
static void
do_remote_set(void *data)
{
union remote_data *x = data;
x->retval = alpha_rtc_set_time(NULL, x->tm);
}
static int
remote_set_time(struct device *dev, struct rtc_time *tm)
{
union remote_data x;
if (smp_processor_id() != boot_cpuid) {
x.tm = tm;
smp_call_function_single(boot_cpuid, do_remote_set, &x, 1);
return x.retval;
}
return alpha_rtc_set_time(NULL, tm);
}
static const struct rtc_class_ops remote_rtc_ops = {
.read_time = remote_read_time,
.set_time = remote_set_time,
.ioctl = alpha_rtc_ioctl,
};
#endif
static int __init
alpha_rtc_init(void)
{
struct platform_device *pdev;
struct rtc_device *rtc;
init_rtc_epoch();
pdev = platform_device_register_simple("rtc-alpha", -1, NULL, 0);
rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
platform_set_drvdata(pdev, rtc);
rtc->ops = &alpha_rtc_ops;
#ifdef HAVE_REMOTE_RTC
if (alpha_mv.rtc_boot_cpu_only)
rtc->ops = &remote_rtc_ops;
#endif
return devm_rtc_register_device(rtc);
}
device_initcall(alpha_rtc_init);
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