1 // SPDX-License-Identifier: GPL-2.0
3 * linux/arch/alpha/kernel/rtc.c
5 * Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds
7 * This file contains date handling.
9 #include <linux/errno.h>
10 #include <linux/init.h>
11 #include <linux/kernel.h>
12 #include <linux/param.h>
13 #include <linux/string.h>
14 #include <linux/mc146818rtc.h>
15 #include <linux/bcd.h>
16 #include <linux/rtc.h>
17 #include <linux/platform_device.h>
23 * Support for the RTC device.
25 * We don't want to use the rtc-cmos driver, because we don't want to support
26 * alarms, as that would be indistinguishable from timer interrupts.
28 * Further, generic code is really, really tied to a 1900 epoch. This is
29 * true in __get_rtc_time as well as the users of struct rtc_time e.g.
30 * rtc_tm_to_time. Thankfully all of the other epochs in use are later
31 * than 1900, and so it's easy to adjust.
34 static unsigned long rtc_epoch;
37 specifiy_epoch(char *str)
39 unsigned long epoch = simple_strtoul(str, NULL, 0);
41 printk("Ignoring invalid user specified epoch %lu\n", epoch);
46 __setup("epoch=", specifiy_epoch);
51 int epoch, year, ctrl;
54 /* The epoch was specified on the command-line. */
58 /* Detect the epoch in use on this computer. */
59 ctrl = CMOS_READ(RTC_CONTROL);
60 year = CMOS_READ(RTC_YEAR);
61 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
64 /* PC-like is standard; used for year >= 70 */
68 } else if (year >= 20 && year < 48) {
71 } else if (year >= 48 && year < 70) {
72 /* Digital UNIX epoch */
77 printk(KERN_INFO "Using epoch %d for rtc year %d\n", epoch, year);
81 alpha_rtc_read_time(struct device *dev, struct rtc_time *tm)
83 mc146818_get_time(tm);
85 /* Adjust for non-default epochs. It's easier to depend on the
86 generic __get_rtc_time and adjust the epoch here than create
87 a copy of __get_rtc_time with the edits we need. */
88 if (rtc_epoch != 1900) {
89 int year = tm->tm_year;
90 /* Undo the century adjustment made in __get_rtc_time. */
93 year += rtc_epoch - 1900;
94 /* Redo the century adjustment with the epoch in place. */
104 alpha_rtc_set_time(struct device *dev, struct rtc_time *tm)
108 if (rtc_epoch != 1900) {
110 xtm.tm_year -= rtc_epoch - 1900;
114 return mc146818_set_time(tm);
118 alpha_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
122 return put_user(rtc_epoch, (unsigned long __user *)arg);
133 static const struct rtc_class_ops alpha_rtc_ops = {
134 .read_time = alpha_rtc_read_time,
135 .set_time = alpha_rtc_set_time,
136 .ioctl = alpha_rtc_ioctl,
140 * Similarly, except do the actual CMOS access on the boot cpu only.
141 * This requires marshalling the data across an interprocessor call.
144 #if defined(CONFIG_SMP) && \
145 (defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_MARVEL))
146 # define HAVE_REMOTE_RTC 1
154 do_remote_read(void *data)
156 union remote_data *x = data;
157 x->retval = alpha_rtc_read_time(NULL, x->tm);
161 remote_read_time(struct device *dev, struct rtc_time *tm)
164 if (smp_processor_id() != boot_cpuid) {
166 smp_call_function_single(boot_cpuid, do_remote_read, &x, 1);
169 return alpha_rtc_read_time(NULL, tm);
173 do_remote_set(void *data)
175 union remote_data *x = data;
176 x->retval = alpha_rtc_set_time(NULL, x->tm);
180 remote_set_time(struct device *dev, struct rtc_time *tm)
183 if (smp_processor_id() != boot_cpuid) {
185 smp_call_function_single(boot_cpuid, do_remote_set, &x, 1);
188 return alpha_rtc_set_time(NULL, tm);
191 static const struct rtc_class_ops remote_rtc_ops = {
192 .read_time = remote_read_time,
193 .set_time = remote_set_time,
194 .ioctl = alpha_rtc_ioctl,
201 const struct rtc_class_ops *ops;
202 struct platform_device *pdev;
203 struct rtc_device *rtc;
208 ops = &alpha_rtc_ops;
210 #ifdef HAVE_REMOTE_RTC
211 if (alpha_mv.rtc_boot_cpu_only)
212 ops = &remote_rtc_ops;
215 pdev = platform_device_register_simple(name, -1, NULL, 0);
216 rtc = devm_rtc_device_register(&pdev->dev, name, ops, THIS_MODULE);
220 platform_set_drvdata(pdev, rtc);
223 device_initcall(alpha_rtc_init);