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 */
25 volatile unsigned long cmos_lock;
26 EXPORT_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
32 DEFINE_SPINLOCK(rtc_lock);
33 EXPORT_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 */
mach_set_rtc_mmss(const struct timespec64 * now)42 int 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
mach_get_cmos_time(struct timespec64 * now)63 void 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. */
rtc_cmos_read(unsigned char addr)126 unsigned 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 }
137 EXPORT_SYMBOL(rtc_cmos_read);
138
rtc_cmos_write(unsigned char val,unsigned char addr)139 void 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 }
146 EXPORT_SYMBOL(rtc_cmos_write);
147
update_persistent_clock64(struct timespec64 now)148 int update_persistent_clock64(struct timespec64 now)
149 {
150 return x86_platform.set_wallclock(&now);
151 }
152
153 /* not static: needed by APM */
read_persistent_clock64(struct timespec64 * ts)154 void read_persistent_clock64(struct timespec64 *ts)
155 {
156 x86_platform.get_wallclock(ts);
157 }
158
159
160 static 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
173 static 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
add_rtc_cmos(void)180 static __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 }
207 device_initcall(add_rtc_cmos);
208