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 */
22 volatile unsigned long cmos_lock;
23 EXPORT_SYMBOL(cmos_lock);
24 #endif /* CONFIG_X86_32 */
25
26 DEFINE_SPINLOCK(rtc_lock);
27 EXPORT_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 */
mach_set_cmos_time(const struct timespec64 * now)36 int 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
mach_get_cmos_time(struct timespec64 * now)57 void 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. */
rtc_cmos_read(unsigned char addr)81 unsigned 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 }
92 EXPORT_SYMBOL(rtc_cmos_read);
93
rtc_cmos_write(unsigned char val,unsigned char addr)94 void 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 }
101 EXPORT_SYMBOL(rtc_cmos_write);
102
update_persistent_clock64(struct timespec64 now)103 int update_persistent_clock64(struct timespec64 now)
104 {
105 return x86_platform.set_wallclock(&now);
106 }
107
108 /* not static: needed by APM */
read_persistent_clock64(struct timespec64 * ts)109 void read_persistent_clock64(struct timespec64 *ts)
110 {
111 x86_platform.get_wallclock(ts);
112 }
113
114
115 static 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
128 static 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
add_rtc_cmos(void)135 static __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 }
159 device_initcall(add_rtc_cmos);
160