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