Line data Source code
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 : */
42 0 : int mach_set_rtc_mmss(const struct timespec64 *now)
43 : {
44 0 : unsigned long long nowtime = now->tv_sec;
45 0 : struct rtc_time tm;
46 0 : int retval = 0;
47 :
48 0 : rtc_time64_to_tm(nowtime, &tm);
49 0 : if (!rtc_valid_tm(&tm)) {
50 0 : retval = mc146818_set_time(&tm);
51 0 : if (retval)
52 0 : printk(KERN_ERR "%s: RTC write failed with error %d\n",
53 : __func__, retval);
54 : } else {
55 0 : printk(KERN_ERR
56 : "%s: Invalid RTC value: write of %llx to RTC failed\n",
57 : __func__, nowtime);
58 0 : retval = -EINVAL;
59 : }
60 0 : return retval;
61 : }
62 :
63 0 : void mach_get_cmos_time(struct timespec64 *now)
64 : {
65 0 : unsigned int status, year, mon, day, hour, min, sec, century = 0;
66 0 : 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 0 : if (!pm_trace_rtc_valid()) {
73 : now->tv_sec = now->tv_nsec = 0;
74 : return;
75 : }
76 :
77 0 : 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 0 : while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
86 0 : cpu_relax();
87 :
88 0 : sec = CMOS_READ(RTC_SECONDS);
89 0 : min = CMOS_READ(RTC_MINUTES);
90 0 : hour = CMOS_READ(RTC_HOURS);
91 0 : day = CMOS_READ(RTC_DAY_OF_MONTH);
92 0 : mon = CMOS_READ(RTC_MONTH);
93 0 : 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 0 : status = CMOS_READ(RTC_CONTROL);
102 0 : WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));
103 :
104 0 : spin_unlock_irqrestore(&rtc_lock, flags);
105 :
106 0 : if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
107 0 : sec = bcd2bin(sec);
108 0 : min = bcd2bin(min);
109 0 : hour = bcd2bin(hour);
110 0 : day = bcd2bin(day);
111 0 : mon = bcd2bin(mon);
112 0 : year = bcd2bin(year);
113 : }
114 :
115 0 : if (century) {
116 : century = bcd2bin(century);
117 : year += century * 100;
118 : } else
119 0 : year += CMOS_YEARS_OFFS;
120 :
121 0 : now->tv_sec = mktime64(year, mon, day, hour, min, sec);
122 0 : now->tv_nsec = 0;
123 : }
124 :
125 : /* Routines for accessing the CMOS RAM/RTC. */
126 1 : unsigned char rtc_cmos_read(unsigned char addr)
127 : {
128 1 : unsigned char val;
129 :
130 1 : lock_cmos_prefix(addr);
131 1 : outb(addr, RTC_PORT(0));
132 1 : val = inb(RTC_PORT(1));
133 1 : lock_cmos_suffix(addr);
134 :
135 0 : return val;
136 : }
137 : EXPORT_SYMBOL(rtc_cmos_read);
138 :
139 6 : void rtc_cmos_write(unsigned char val, unsigned char addr)
140 : {
141 6 : lock_cmos_prefix(addr);
142 6 : outb(addr, RTC_PORT(0));
143 6 : outb(val, RTC_PORT(1));
144 6 : lock_cmos_suffix(addr);
145 6 : }
146 : EXPORT_SYMBOL(rtc_cmos_write);
147 :
148 0 : int update_persistent_clock64(struct timespec64 now)
149 : {
150 0 : return x86_platform.set_wallclock(&now);
151 : }
152 :
153 : /* not static: needed by APM */
154 1 : void read_persistent_clock64(struct timespec64 *ts)
155 : {
156 1 : x86_platform.get_wallclock(ts);
157 1 : }
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 :
180 1 : 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 1 : if (!x86_platform.legacy.rtc)
199 : return -ENODEV;
200 :
201 1 : platform_device_register(&rtc_device);
202 1 : dev_info(&rtc_device.dev,
203 : "registered platform RTC device (no PNP device found)\n");
204 :
205 1 : return 0;
206 : }
207 : device_initcall(add_rtc_cmos);
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