Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
fe599f9f | 2 | * RTC related functions |
1da177e4 | 3 | */ |
1122b134 | 4 | #include <linux/acpi.h> |
fe599f9f | 5 | #include <linux/bcd.h> |
1da177e4 LT |
6 | #include <linux/mc146818rtc.h> |
7 | ||
fe599f9f | 8 | #include <asm/time.h> |
1da177e4 | 9 | |
1122b134 TG |
10 | #ifdef CONFIG_X86_32 |
11 | # define CMOS_YEARS_OFFS 1900 | |
12 | /* | |
13 | * This is a special lock that is owned by the CPU and holds the index | |
14 | * register we are working with. It is required for NMI access to the | |
15 | * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. | |
16 | */ | |
17 | volatile unsigned long cmos_lock = 0; | |
18 | EXPORT_SYMBOL(cmos_lock); | |
19 | #else | |
20 | /* | |
21 | * x86-64 systems only exists since 2002. | |
22 | * This will work up to Dec 31, 2100 | |
23 | */ | |
24 | # define CMOS_YEARS_OFFS 2000 | |
25 | #endif | |
26 | ||
27 | DEFINE_SPINLOCK(rtc_lock); | |
28 | EXPORT_SYMBOL(rtc_lock); | |
29 | ||
1da177e4 LT |
30 | /* |
31 | * In order to set the CMOS clock precisely, set_rtc_mmss has to be | |
32 | * called 500 ms after the second nowtime has started, because when | |
33 | * nowtime is written into the registers of the CMOS clock, it will | |
34 | * jump to the next second precisely 500 ms later. Check the Motorola | |
35 | * MC146818A or Dallas DS12887 data sheet for details. | |
36 | * | |
37 | * BUG: This routine does not handle hour overflow properly; it just | |
38 | * sets the minutes. Usually you'll only notice that after reboot! | |
39 | */ | |
fe599f9f | 40 | int mach_set_rtc_mmss(unsigned long nowtime) |
1da177e4 LT |
41 | { |
42 | int retval = 0; | |
43 | int real_seconds, real_minutes, cmos_minutes; | |
44 | unsigned char save_control, save_freq_select; | |
45 | ||
1122b134 TG |
46 | /* tell the clock it's being set */ |
47 | save_control = CMOS_READ(RTC_CONTROL); | |
1da177e4 LT |
48 | CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); |
49 | ||
1122b134 TG |
50 | /* stop and reset prescaler */ |
51 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); | |
1da177e4 LT |
52 | CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); |
53 | ||
54 | cmos_minutes = CMOS_READ(RTC_MINUTES); | |
55 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) | |
56 | BCD_TO_BIN(cmos_minutes); | |
57 | ||
58 | /* | |
59 | * since we're only adjusting minutes and seconds, | |
60 | * don't interfere with hour overflow. This avoids | |
61 | * messing with unknown time zones but requires your | |
62 | * RTC not to be off by more than 15 minutes | |
63 | */ | |
64 | real_seconds = nowtime % 60; | |
65 | real_minutes = nowtime / 60; | |
1122b134 | 66 | /* correct for half hour time zone */ |
1da177e4 | 67 | if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) |
1122b134 | 68 | real_minutes += 30; |
1da177e4 LT |
69 | real_minutes %= 60; |
70 | ||
71 | if (abs(real_minutes - cmos_minutes) < 30) { | |
72 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { | |
73 | BIN_TO_BCD(real_seconds); | |
74 | BIN_TO_BCD(real_minutes); | |
75 | } | |
76 | CMOS_WRITE(real_seconds,RTC_SECONDS); | |
77 | CMOS_WRITE(real_minutes,RTC_MINUTES); | |
78 | } else { | |
79 | printk(KERN_WARNING | |
80 | "set_rtc_mmss: can't update from %d to %d\n", | |
81 | cmos_minutes, real_minutes); | |
82 | retval = -1; | |
83 | } | |
84 | ||
85 | /* The following flags have to be released exactly in this order, | |
86 | * otherwise the DS12887 (popular MC146818A clone with integrated | |
87 | * battery and quartz) will not reset the oscillator and will not | |
88 | * update precisely 500 ms later. You won't find this mentioned in | |
89 | * the Dallas Semiconductor data sheets, but who believes data | |
90 | * sheets anyway ... -- Markus Kuhn | |
91 | */ | |
92 | CMOS_WRITE(save_control, RTC_CONTROL); | |
93 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); | |
94 | ||
95 | return retval; | |
96 | } | |
97 | ||
fe599f9f | 98 | unsigned long mach_get_cmos_time(void) |
1da177e4 | 99 | { |
1122b134 TG |
100 | unsigned int year, mon, day, hour, min, sec, century = 0; |
101 | ||
102 | /* | |
103 | * If UIP is clear, then we have >= 244 microseconds before | |
104 | * RTC registers will be updated. Spec sheet says that this | |
105 | * is the reliable way to read RTC - registers. If UIP is set | |
106 | * then the register access might be invalid. | |
107 | */ | |
108 | while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)) | |
109 | cpu_relax(); | |
110 | ||
111 | sec = CMOS_READ(RTC_SECONDS); | |
112 | min = CMOS_READ(RTC_MINUTES); | |
113 | hour = CMOS_READ(RTC_HOURS); | |
114 | day = CMOS_READ(RTC_DAY_OF_MONTH); | |
115 | mon = CMOS_READ(RTC_MONTH); | |
116 | year = CMOS_READ(RTC_YEAR); | |
117 | ||
118 | #if defined(CONFIG_ACPI) && defined(CONFIG_X86_64) | |
119 | /* CHECKME: Is this really 64bit only ??? */ | |
120 | if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && | |
121 | acpi_gbl_FADT.century) | |
122 | century = CMOS_READ(acpi_gbl_FADT.century); | |
123 | #endif | |
124 | ||
125 | if (RTC_ALWAYS_BCD || !(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)) { | |
41623b06 MM |
126 | BCD_TO_BIN(sec); |
127 | BCD_TO_BIN(min); | |
128 | BCD_TO_BIN(hour); | |
129 | BCD_TO_BIN(day); | |
130 | BCD_TO_BIN(mon); | |
131 | BCD_TO_BIN(year); | |
132 | } | |
133 | ||
1122b134 TG |
134 | if (century) { |
135 | BCD_TO_BIN(century); | |
136 | year += century * 100; | |
137 | printk(KERN_INFO "Extended CMOS year: %d\n", century * 100); | |
138 | } else { | |
139 | year += CMOS_YEARS_OFFS; | |
140 | if (year < 1970) | |
141 | year += 100; | |
142 | } | |
1da177e4 LT |
143 | |
144 | return mktime(year, mon, day, hour, min, sec); | |
145 | } | |
146 | ||
fe599f9f TG |
147 | /* Routines for accessing the CMOS RAM/RTC. */ |
148 | unsigned char rtc_cmos_read(unsigned char addr) | |
149 | { | |
150 | unsigned char val; | |
151 | ||
152 | lock_cmos_prefix(addr); | |
153 | outb_p(addr, RTC_PORT(0)); | |
154 | val = inb_p(RTC_PORT(1)); | |
155 | lock_cmos_suffix(addr); | |
156 | return val; | |
157 | } | |
158 | EXPORT_SYMBOL(rtc_cmos_read); | |
159 | ||
160 | void rtc_cmos_write(unsigned char val, unsigned char addr) | |
161 | { | |
162 | lock_cmos_prefix(addr); | |
163 | outb_p(addr, RTC_PORT(0)); | |
164 | outb_p(val, RTC_PORT(1)); | |
165 | lock_cmos_suffix(addr); | |
166 | } | |
167 | EXPORT_SYMBOL(rtc_cmos_write); | |
168 | ||
169 | static int set_rtc_mmss(unsigned long nowtime) | |
170 | { | |
171 | int retval; | |
172 | unsigned long flags; | |
173 | ||
fe599f9f TG |
174 | spin_lock_irqsave(&rtc_lock, flags); |
175 | retval = set_wallclock(nowtime); | |
176 | spin_unlock_irqrestore(&rtc_lock, flags); | |
177 | ||
178 | return retval; | |
179 | } | |
180 | ||
181 | /* not static: needed by APM */ | |
182 | unsigned long read_persistent_clock(void) | |
183 | { | |
1122b134 | 184 | unsigned long retval, flags; |
fe599f9f TG |
185 | |
186 | spin_lock_irqsave(&rtc_lock, flags); | |
187 | retval = get_wallclock(); | |
188 | spin_unlock_irqrestore(&rtc_lock, flags); | |
189 | ||
190 | return retval; | |
191 | } | |
192 | ||
193 | int update_persistent_clock(struct timespec now) | |
194 | { | |
195 | return set_rtc_mmss(now.tv_sec); | |
196 | } |