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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/acpi.h>
8#include <linux/bcd.h>
9#include <linux/export.h>
10#include <linux/pnp.h>
11#include <linux/of.h>
12
13#include <asm/vsyscall.h>
14#include <asm/x86_init.h>
15#include <asm/time.h>
16#include <asm/intel-mid.h>
17#include <asm/setup.h>
18
19#ifdef CONFIG_X86_32
20/*
21 * This is a special lock that is owned by the CPU and holds the index
22 * register we are working with. It is required for NMI access to the
23 * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
24 */
25volatile unsigned long cmos_lock;
26EXPORT_SYMBOL(cmos_lock);
27#endif /* CONFIG_X86_32 */
28
29/* For two digit years assume time is always after that */
30#define CMOS_YEARS_OFFS 2000
31
32DEFINE_SPINLOCK(rtc_lock);
33EXPORT_SYMBOL(rtc_lock);
34
35/*
36 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
37 * called 500 ms after the second nowtime has started, because when
38 * nowtime is written into the registers of the CMOS clock, it will
39 * jump to the next second precisely 500 ms later. Check the Motorola
40 * MC146818A or Dallas DS12887 data sheet for details.
41 */
42int mach_set_rtc_mmss(const struct timespec64 *now)
43{
44 unsigned long long nowtime = now->tv_sec;
45 struct rtc_time tm;
46 int retval = 0;
47
48 rtc_time64_to_tm(nowtime, &tm);
49 if (!rtc_valid_tm(&tm)) {
50 retval = mc146818_set_time(&tm);
51 if (retval)
52 printk(KERN_ERR "%s: RTC write failed with error %d\n",
53 __func__, retval);
54 } else {
55 printk(KERN_ERR
56 "%s: Invalid RTC value: write of %llx to RTC failed\n",
57 __func__, nowtime);
58 retval = -EINVAL;
59 }
60 return retval;
61}
62
63void mach_get_cmos_time(struct timespec64 *now)
64{
65 unsigned int status, year, mon, day, hour, min, sec, century = 0;
66 unsigned long flags;
67
68 /*
69 * If pm_trace abused the RTC as storage, set the timespec to 0,
70 * which tells the caller that this RTC value is unusable.
71 */
72 if (!pm_trace_rtc_valid()) {
73 now->tv_sec = now->tv_nsec = 0;
74 return;
75 }
76
77 spin_lock_irqsave(&rtc_lock, flags);
78
79 /*
80 * If UIP is clear, then we have >= 244 microseconds before
81 * RTC registers will be updated. Spec sheet says that this
82 * is the reliable way to read RTC - registers. If UIP is set
83 * then the register access might be invalid.
84 */
85 while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
86 cpu_relax();
87
88 sec = CMOS_READ(RTC_SECONDS);
89 min = CMOS_READ(RTC_MINUTES);
90 hour = CMOS_READ(RTC_HOURS);
91 day = CMOS_READ(RTC_DAY_OF_MONTH);
92 mon = CMOS_READ(RTC_MONTH);
93 year = CMOS_READ(RTC_YEAR);
94
95#ifdef CONFIG_ACPI
96 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
97 acpi_gbl_FADT.century)
98 century = CMOS_READ(acpi_gbl_FADT.century);
99#endif
100
101 status = CMOS_READ(RTC_CONTROL);
102 WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
103
104 spin_unlock_irqrestore(&rtc_lock, flags);
105
106 if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
107 sec = bcd2bin(sec);
108 min = bcd2bin(min);
109 hour = bcd2bin(hour);
110 day = bcd2bin(day);
111 mon = bcd2bin(mon);
112 year = bcd2bin(year);
113 }
114
115 if (century) {
116 century = bcd2bin(century);
117 year += century * 100;
118 } else
119 year += CMOS_YEARS_OFFS;
120
121 now->tv_sec = mktime64(year, mon, day, hour, min, sec);
122 now->tv_nsec = 0;
123}
124
125/* Routines for accessing the CMOS RAM/RTC. */
126unsigned char rtc_cmos_read(unsigned char addr)
127{
128 unsigned char val;
129
130 lock_cmos_prefix(addr);
131 outb(addr, RTC_PORT(0));
132 val = inb(RTC_PORT(1));
133 lock_cmos_suffix(addr);
134
135 return val;
136}
137EXPORT_SYMBOL(rtc_cmos_read);
138
139void rtc_cmos_write(unsigned char val, unsigned char addr)
140{
141 lock_cmos_prefix(addr);
142 outb(addr, RTC_PORT(0));
143 outb(val, RTC_PORT(1));
144 lock_cmos_suffix(addr);
145}
146EXPORT_SYMBOL(rtc_cmos_write);
147
148int update_persistent_clock64(struct timespec64 now)
149{
150 return x86_platform.set_wallclock(&now);
151}
152
153/* not static: needed by APM */
154void read_persistent_clock64(struct timespec64 *ts)
155{
156 x86_platform.get_wallclock(ts);
157}
158
159
160static struct resource rtc_resources[] = {
161 [0] = {
162 .start = RTC_PORT(0),
163 .end = RTC_PORT(1),
164 .flags = IORESOURCE_IO,
165 },
166 [1] = {
167 .start = RTC_IRQ,
168 .end = RTC_IRQ,
169 .flags = IORESOURCE_IRQ,
170 }
171};
172
173static struct platform_device rtc_device = {
174 .name = "rtc_cmos",
175 .id = -1,
176 .resource = rtc_resources,
177 .num_resources = ARRAY_SIZE(rtc_resources),
178};
179
180static __init int add_rtc_cmos(void)
181{
182#ifdef CONFIG_PNP
183 static const char * const ids[] __initconst =
184 { "PNP0b00", "PNP0b01", "PNP0b02", };
185 struct pnp_dev *dev;
186 struct pnp_id *id;
187 int i;
188
189 pnp_for_each_dev(dev) {
190 for (id = dev->id; id; id = id->next) {
191 for (i = 0; i < ARRAY_SIZE(ids); i++) {
192 if (compare_pnp_id(id, ids[i]) != 0)
193 return 0;
194 }
195 }
196 }
197#endif
198 if (!x86_platform.legacy.rtc)
199 return -ENODEV;
200
201 platform_device_register(&rtc_device);
202 dev_info(&rtc_device.dev,
203 "registered platform RTC device (no PNP device found)\n");
204
205 return 0;
206}
207device_initcall(add_rtc_cmos);
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);