1// SPDX-License-Identifier: GPL-2.0
2/*
3 * RTC related functions
4 */
5#include <linux/platform_device.h>
6#include <linux/mc146818rtc.h>
7#include <linux/export.h>
8#include <linux/pnp.h>
9
10#include <asm/vsyscall.h>
11#include <asm/x86_init.h>
12#include <asm/time.h>
13#include <asm/intel-mid.h>
14#include <asm/setup.h>
15
16#ifdef CONFIG_X86_32
17/*
18 * This is a special lock that is owned by the CPU and holds the index
19 * register we are working with.  It is required for NMI access to the
20 * CMOS/RTC registers.  See arch/x86/include/asm/mc146818rtc.h for details.
21 */
22volatile unsigned long cmos_lock;
23EXPORT_SYMBOL(cmos_lock);
24#endif /* CONFIG_X86_32 */
25
26DEFINE_SPINLOCK(rtc_lock);
27EXPORT_SYMBOL(rtc_lock);
28
29/*
30 * In order to set the CMOS clock precisely, mach_set_cmos_time has to be
31 * called 500 ms after the second nowtime has started, because when
32 * nowtime is written into the registers of the CMOS clock, it will
33 * jump to the next second precisely 500 ms later. Check the Motorola
34 * MC146818A or Dallas DS12887 data sheet for details.
35 */
36int mach_set_cmos_time(const struct timespec64 *now)
37{
38	unsigned long long nowtime = now->tv_sec;
39	struct rtc_time tm;
40	int retval = 0;
41
42	rtc_time64_to_tm(nowtime, &tm);
43	if (!rtc_valid_tm(&tm)) {
44		retval = mc146818_set_time(&tm);
45		if (retval)
46			printk(KERN_ERR "%s: RTC write failed with error %d\n",
47			       __func__, retval);
48	} else {
49		printk(KERN_ERR
50		       "%s: Invalid RTC value: write of %llx to RTC failed\n",
51			__func__, nowtime);
52		retval = -EINVAL;
53	}
54	return retval;
55}
56
57void mach_get_cmos_time(struct timespec64 *now)
58{
59	struct rtc_time tm;
60
61	/*
62	 * If pm_trace abused the RTC as storage, set the timespec to 0,
63	 * which tells the caller that this RTC value is unusable.
64	 */
65	if (!pm_trace_rtc_valid()) {
66		now->tv_sec = now->tv_nsec = 0;
67		return;
68	}
69
70	if (mc146818_get_time(&tm, 1000)) {
71		pr_err("Unable to read current time from RTC\n");
72		now->tv_sec = now->tv_nsec = 0;
73		return;
74	}
75
76	now->tv_sec = rtc_tm_to_time64(&tm);
77	now->tv_nsec = 0;
78}
79
80/* Routines for accessing the CMOS RAM/RTC. */
81unsigned char rtc_cmos_read(unsigned char addr)
82{
83	unsigned char val;
84
85	lock_cmos_prefix(addr);
86	outb(addr, RTC_PORT(0));
87	val = inb(RTC_PORT(1));
88	lock_cmos_suffix(addr);
89
90	return val;
91}
92EXPORT_SYMBOL(rtc_cmos_read);
93
94void rtc_cmos_write(unsigned char val, unsigned char addr)
95{
96	lock_cmos_prefix(addr);
97	outb(addr, RTC_PORT(0));
98	outb(val, RTC_PORT(1));
99	lock_cmos_suffix(addr);
100}
101EXPORT_SYMBOL(rtc_cmos_write);
102
103int update_persistent_clock64(struct timespec64 now)
104{
105	return x86_platform.set_wallclock(&now);
106}
107
108/* not static: needed by APM */
109void read_persistent_clock64(struct timespec64 *ts)
110{
111	x86_platform.get_wallclock(ts);
112}
113
114
115static struct resource rtc_resources[] = {
116	[0] = {
117		.start	= RTC_PORT(0),
118		.end	= RTC_PORT(1),
119		.flags	= IORESOURCE_IO,
120	},
121	[1] = {
122		.start	= RTC_IRQ,
123		.end	= RTC_IRQ,
124		.flags	= IORESOURCE_IRQ,
125	}
126};
127
128static struct platform_device rtc_device = {
129	.name		= "rtc_cmos",
130	.id		= -1,
131	.resource	= rtc_resources,
132	.num_resources	= ARRAY_SIZE(rtc_resources),
133};
134
135static __init int add_rtc_cmos(void)
136{
137#ifdef CONFIG_PNP
138	static const char * const ids[] __initconst =
139	    { "PNP0b00", "PNP0b01", "PNP0b02", };
140	struct pnp_dev *dev;
141	int i;
142
143	pnp_for_each_dev(dev) {
144		for (i = 0; i < ARRAY_SIZE(ids); i++) {
145			if (compare_pnp_id(dev->id, ids[i]) != 0)
146				return 0;
147		}
148	}
149#endif
150	if (!x86_platform.legacy.rtc)
151		return -ENODEV;
152
153	platform_device_register(&rtc_device);
154	dev_info(&rtc_device.dev,
155		 "registered platform RTC device (no PNP device found)\n");
156
157	return 0;
158}
159device_initcall(add_rtc_cmos);
160