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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/*
2 * RTC related functions
3 */
4#include <linux/platform_device.h>
5#include <linux/mc146818rtc.h>
6#include <linux/acpi.h>
7#include <linux/bcd.h>
8#include <linux/pnp.h>
9#include <linux/of.h>
10
11#include <asm/vsyscall.h>
12#include <asm/x86_init.h>
13#include <asm/time.h>
14
15#ifdef CONFIG_X86_32
16/*
17 * This is a special lock that is owned by the CPU and holds the index
18 * register we are working with. It is required for NMI access to the
19 * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
20 */
21volatile unsigned long cmos_lock;
22EXPORT_SYMBOL(cmos_lock);
23#endif /* CONFIG_X86_32 */
24
25/* For two digit years assume time is always after that */
26#define CMOS_YEARS_OFFS 2000
27
28DEFINE_SPINLOCK(rtc_lock);
29EXPORT_SYMBOL(rtc_lock);
30
31/*
32 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
33 * called 500 ms after the second nowtime has started, because when
34 * nowtime is written into the registers of the CMOS clock, it will
35 * jump to the next second precisely 500 ms later. Check the Motorola
36 * MC146818A or Dallas DS12887 data sheet for details.
37 *
38 * BUG: This routine does not handle hour overflow properly; it just
39 * sets the minutes. Usually you'll only notice that after reboot!
40 */
41int mach_set_rtc_mmss(unsigned long nowtime)
42{
43 int real_seconds, real_minutes, cmos_minutes;
44 unsigned char save_control, save_freq_select;
45 unsigned long flags;
46 int retval = 0;
47
48 spin_lock_irqsave(&rtc_lock, flags);
49
50 /* tell the clock it's being set */
51 save_control = CMOS_READ(RTC_CONTROL);
52 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
53
54 /* stop and reset prescaler */
55 save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
56 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
57
58 cmos_minutes = CMOS_READ(RTC_MINUTES);
59 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
60 cmos_minutes = bcd2bin(cmos_minutes);
61
62 /*
63 * since we're only adjusting minutes and seconds,
64 * don't interfere with hour overflow. This avoids
65 * messing with unknown time zones but requires your
66 * RTC not to be off by more than 15 minutes
67 */
68 real_seconds = nowtime % 60;
69 real_minutes = nowtime / 60;
70 /* correct for half hour time zone */
71 if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
72 real_minutes += 30;
73 real_minutes %= 60;
74
75 if (abs(real_minutes - cmos_minutes) < 30) {
76 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
77 real_seconds = bin2bcd(real_seconds);
78 real_minutes = bin2bcd(real_minutes);
79 }
80 CMOS_WRITE(real_seconds, RTC_SECONDS);
81 CMOS_WRITE(real_minutes, RTC_MINUTES);
82 } else {
83 printk_once(KERN_NOTICE
84 "set_rtc_mmss: can't update from %d to %d\n",
85 cmos_minutes, real_minutes);
86 retval = -1;
87 }
88
89 /* The following flags have to be released exactly in this order,
90 * otherwise the DS12887 (popular MC146818A clone with integrated
91 * battery and quartz) will not reset the oscillator and will not
92 * update precisely 500 ms later. You won't find this mentioned in
93 * the Dallas Semiconductor data sheets, but who believes data
94 * sheets anyway ... -- Markus Kuhn
95 */
96 CMOS_WRITE(save_control, RTC_CONTROL);
97 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
98
99 spin_unlock_irqrestore(&rtc_lock, flags);
100
101 return retval;
102}
103
104unsigned long mach_get_cmos_time(void)
105{
106 unsigned int status, year, mon, day, hour, min, sec, century = 0;
107 unsigned long flags;
108
109 spin_lock_irqsave(&rtc_lock, flags);
110
111 /*
112 * If UIP is clear, then we have >= 244 microseconds before
113 * RTC registers will be updated. Spec sheet says that this
114 * is the reliable way to read RTC - registers. If UIP is set
115 * then the register access might be invalid.
116 */
117 while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
118 cpu_relax();
119
120 sec = CMOS_READ(RTC_SECONDS);
121 min = CMOS_READ(RTC_MINUTES);
122 hour = CMOS_READ(RTC_HOURS);
123 day = CMOS_READ(RTC_DAY_OF_MONTH);
124 mon = CMOS_READ(RTC_MONTH);
125 year = CMOS_READ(RTC_YEAR);
126
127#ifdef CONFIG_ACPI
128 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
129 acpi_gbl_FADT.century)
130 century = CMOS_READ(acpi_gbl_FADT.century);
131#endif
132
133 status = CMOS_READ(RTC_CONTROL);
134 WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
135
136 spin_unlock_irqrestore(&rtc_lock, flags);
137
138 if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
139 sec = bcd2bin(sec);
140 min = bcd2bin(min);
141 hour = bcd2bin(hour);
142 day = bcd2bin(day);
143 mon = bcd2bin(mon);
144 year = bcd2bin(year);
145 }
146
147 if (century) {
148 century = bcd2bin(century);
149 year += century * 100;
150 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
151 } else
152 year += CMOS_YEARS_OFFS;
153
154 return mktime(year, mon, day, hour, min, sec);
155}
156
157/* Routines for accessing the CMOS RAM/RTC. */
158unsigned char rtc_cmos_read(unsigned char addr)
159{
160 unsigned char val;
161
162 lock_cmos_prefix(addr);
163 outb(addr, RTC_PORT(0));
164 val = inb(RTC_PORT(1));
165 lock_cmos_suffix(addr);
166
167 return val;
168}
169EXPORT_SYMBOL(rtc_cmos_read);
170
171void rtc_cmos_write(unsigned char val, unsigned char addr)
172{
173 lock_cmos_prefix(addr);
174 outb(addr, RTC_PORT(0));
175 outb(val, RTC_PORT(1));
176 lock_cmos_suffix(addr);
177}
178EXPORT_SYMBOL(rtc_cmos_write);
179
180int update_persistent_clock(struct timespec now)
181{
182 return x86_platform.set_wallclock(now.tv_sec);
183}
184
185/* not static: needed by APM */
186void read_persistent_clock(struct timespec *ts)
187{
188 unsigned long retval;
189
190 retval = x86_platform.get_wallclock();
191
192 ts->tv_sec = retval;
193 ts->tv_nsec = 0;
194}
195
196unsigned long long native_read_tsc(void)
197{
198 return __native_read_tsc();
199}
200EXPORT_SYMBOL(native_read_tsc);
201
202
203static struct resource rtc_resources[] = {
204 [0] = {
205 .start = RTC_PORT(0),
206 .end = RTC_PORT(1),
207 .flags = IORESOURCE_IO,
208 },
209 [1] = {
210 .start = RTC_IRQ,
211 .end = RTC_IRQ,
212 .flags = IORESOURCE_IRQ,
213 }
214};
215
216static struct platform_device rtc_device = {
217 .name = "rtc_cmos",
218 .id = -1,
219 .resource = rtc_resources,
220 .num_resources = ARRAY_SIZE(rtc_resources),
221};
222
223static __init int add_rtc_cmos(void)
224{
225#ifdef CONFIG_PNP
226 static const char *ids[] __initconst =
227 { "PNP0b00", "PNP0b01", "PNP0b02", };
228 struct pnp_dev *dev;
229 struct pnp_id *id;
230 int i;
231
232 pnp_for_each_dev(dev) {
233 for (id = dev->id; id; id = id->next) {
234 for (i = 0; i < ARRAY_SIZE(ids); i++) {
235 if (compare_pnp_id(id, ids[i]) != 0)
236 return 0;
237 }
238 }
239 }
240#endif
241 if (of_have_populated_dt())
242 return 0;
243
244 platform_device_register(&rtc_device);
245 dev_info(&rtc_device.dev,
246 "registered platform RTC device (no PNP device found)\n");
247
248 return 0;
249}
250device_initcall(add_rtc_cmos);