Loading...
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/export.h>
9#include <linux/pnp.h>
10#include <linux/of.h>
11
12#include <asm/vsyscall.h>
13#include <asm/x86_init.h>
14#include <asm/time.h>
15#include <asm/mrst.h>
16
17#ifdef CONFIG_X86_32
18/*
19 * This is a special lock that is owned by the CPU and holds the index
20 * register we are working with. It is required for NMI access to the
21 * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
22 */
23volatile unsigned long cmos_lock;
24EXPORT_SYMBOL(cmos_lock);
25#endif /* CONFIG_X86_32 */
26
27/* For two digit years assume time is always after that */
28#define CMOS_YEARS_OFFS 2000
29
30DEFINE_SPINLOCK(rtc_lock);
31EXPORT_SYMBOL(rtc_lock);
32
33/*
34 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
35 * called 500 ms after the second nowtime has started, because when
36 * nowtime is written into the registers of the CMOS clock, it will
37 * jump to the next second precisely 500 ms later. Check the Motorola
38 * MC146818A or Dallas DS12887 data sheet for details.
39 *
40 * BUG: This routine does not handle hour overflow properly; it just
41 * sets the minutes. Usually you'll only notice that after reboot!
42 */
43int mach_set_rtc_mmss(unsigned long nowtime)
44{
45 int real_seconds, real_minutes, cmos_minutes;
46 unsigned char save_control, save_freq_select;
47 unsigned long flags;
48 int retval = 0;
49
50 spin_lock_irqsave(&rtc_lock, flags);
51
52 /* tell the clock it's being set */
53 save_control = CMOS_READ(RTC_CONTROL);
54 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
55
56 /* stop and reset prescaler */
57 save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
58 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
59
60 cmos_minutes = CMOS_READ(RTC_MINUTES);
61 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
62 cmos_minutes = bcd2bin(cmos_minutes);
63
64 /*
65 * since we're only adjusting minutes and seconds,
66 * don't interfere with hour overflow. This avoids
67 * messing with unknown time zones but requires your
68 * RTC not to be off by more than 15 minutes
69 */
70 real_seconds = nowtime % 60;
71 real_minutes = nowtime / 60;
72 /* correct for half hour time zone */
73 if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
74 real_minutes += 30;
75 real_minutes %= 60;
76
77 if (abs(real_minutes - cmos_minutes) < 30) {
78 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
79 real_seconds = bin2bcd(real_seconds);
80 real_minutes = bin2bcd(real_minutes);
81 }
82 CMOS_WRITE(real_seconds, RTC_SECONDS);
83 CMOS_WRITE(real_minutes, RTC_MINUTES);
84 } else {
85 printk_once(KERN_NOTICE
86 "set_rtc_mmss: can't update from %d to %d\n",
87 cmos_minutes, real_minutes);
88 retval = -1;
89 }
90
91 /* The following flags have to be released exactly in this order,
92 * otherwise the DS12887 (popular MC146818A clone with integrated
93 * battery and quartz) will not reset the oscillator and will not
94 * update precisely 500 ms later. You won't find this mentioned in
95 * the Dallas Semiconductor data sheets, but who believes data
96 * sheets anyway ... -- Markus Kuhn
97 */
98 CMOS_WRITE(save_control, RTC_CONTROL);
99 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
100
101 spin_unlock_irqrestore(&rtc_lock, flags);
102
103 return retval;
104}
105
106unsigned long mach_get_cmos_time(void)
107{
108 unsigned int status, year, mon, day, hour, min, sec, century = 0;
109 unsigned long flags;
110
111 spin_lock_irqsave(&rtc_lock, flags);
112
113 /*
114 * If UIP is clear, then we have >= 244 microseconds before
115 * RTC registers will be updated. Spec sheet says that this
116 * is the reliable way to read RTC - registers. If UIP is set
117 * then the register access might be invalid.
118 */
119 while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
120 cpu_relax();
121
122 sec = CMOS_READ(RTC_SECONDS);
123 min = CMOS_READ(RTC_MINUTES);
124 hour = CMOS_READ(RTC_HOURS);
125 day = CMOS_READ(RTC_DAY_OF_MONTH);
126 mon = CMOS_READ(RTC_MONTH);
127 year = CMOS_READ(RTC_YEAR);
128
129#ifdef CONFIG_ACPI
130 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
131 acpi_gbl_FADT.century)
132 century = CMOS_READ(acpi_gbl_FADT.century);
133#endif
134
135 status = CMOS_READ(RTC_CONTROL);
136 WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
137
138 spin_unlock_irqrestore(&rtc_lock, flags);
139
140 if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
141 sec = bcd2bin(sec);
142 min = bcd2bin(min);
143 hour = bcd2bin(hour);
144 day = bcd2bin(day);
145 mon = bcd2bin(mon);
146 year = bcd2bin(year);
147 }
148
149 if (century) {
150 century = bcd2bin(century);
151 year += century * 100;
152 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
153 } else
154 year += CMOS_YEARS_OFFS;
155
156 return mktime(year, mon, day, hour, min, sec);
157}
158
159/* Routines for accessing the CMOS RAM/RTC. */
160unsigned char rtc_cmos_read(unsigned char addr)
161{
162 unsigned char val;
163
164 lock_cmos_prefix(addr);
165 outb(addr, RTC_PORT(0));
166 val = inb(RTC_PORT(1));
167 lock_cmos_suffix(addr);
168
169 return val;
170}
171EXPORT_SYMBOL(rtc_cmos_read);
172
173void rtc_cmos_write(unsigned char val, unsigned char addr)
174{
175 lock_cmos_prefix(addr);
176 outb(addr, RTC_PORT(0));
177 outb(val, RTC_PORT(1));
178 lock_cmos_suffix(addr);
179}
180EXPORT_SYMBOL(rtc_cmos_write);
181
182int update_persistent_clock(struct timespec now)
183{
184 return x86_platform.set_wallclock(now.tv_sec);
185}
186
187/* not static: needed by APM */
188void read_persistent_clock(struct timespec *ts)
189{
190 unsigned long retval;
191
192 retval = x86_platform.get_wallclock();
193
194 ts->tv_sec = retval;
195 ts->tv_nsec = 0;
196}
197
198unsigned long long native_read_tsc(void)
199{
200 return __native_read_tsc();
201}
202EXPORT_SYMBOL(native_read_tsc);
203
204
205static struct resource rtc_resources[] = {
206 [0] = {
207 .start = RTC_PORT(0),
208 .end = RTC_PORT(1),
209 .flags = IORESOURCE_IO,
210 },
211 [1] = {
212 .start = RTC_IRQ,
213 .end = RTC_IRQ,
214 .flags = IORESOURCE_IRQ,
215 }
216};
217
218static struct platform_device rtc_device = {
219 .name = "rtc_cmos",
220 .id = -1,
221 .resource = rtc_resources,
222 .num_resources = ARRAY_SIZE(rtc_resources),
223};
224
225static __init int add_rtc_cmos(void)
226{
227#ifdef CONFIG_PNP
228 static const char *ids[] __initconst =
229 { "PNP0b00", "PNP0b01", "PNP0b02", };
230 struct pnp_dev *dev;
231 struct pnp_id *id;
232 int i;
233
234 pnp_for_each_dev(dev) {
235 for (id = dev->id; id; id = id->next) {
236 for (i = 0; i < ARRAY_SIZE(ids); i++) {
237 if (compare_pnp_id(id, ids[i]) != 0)
238 return 0;
239 }
240 }
241 }
242#endif
243 if (of_have_populated_dt())
244 return 0;
245
246 /* Intel MID platforms don't have ioport rtc */
247 if (mrst_identify_cpu())
248 return -ENODEV;
249
250 platform_device_register(&rtc_device);
251 dev_info(&rtc_device.dev,
252 "registered platform RTC device (no PNP device found)\n");
253
254 return 0;
255}
256device_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);