Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
fe599f9f | 2 | * RTC related functions |
1da177e4 | 3 | */ |
fe599f9f | 4 | #include <linux/bcd.h> |
1da177e4 LT |
5 | #include <linux/mc146818rtc.h> |
6 | ||
fe599f9f | 7 | #include <asm/time.h> |
1da177e4 LT |
8 | |
9 | /* | |
10 | * In order to set the CMOS clock precisely, set_rtc_mmss has to be | |
11 | * called 500 ms after the second nowtime has started, because when | |
12 | * nowtime is written into the registers of the CMOS clock, it will | |
13 | * jump to the next second precisely 500 ms later. Check the Motorola | |
14 | * MC146818A or Dallas DS12887 data sheet for details. | |
15 | * | |
16 | * BUG: This routine does not handle hour overflow properly; it just | |
17 | * sets the minutes. Usually you'll only notice that after reboot! | |
18 | */ | |
fe599f9f | 19 | int mach_set_rtc_mmss(unsigned long nowtime) |
1da177e4 LT |
20 | { |
21 | int retval = 0; | |
22 | int real_seconds, real_minutes, cmos_minutes; | |
23 | unsigned char save_control, save_freq_select; | |
24 | ||
25 | save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */ | |
26 | CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); | |
27 | ||
28 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */ | |
29 | CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); | |
30 | ||
31 | cmos_minutes = CMOS_READ(RTC_MINUTES); | |
32 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) | |
33 | BCD_TO_BIN(cmos_minutes); | |
34 | ||
35 | /* | |
36 | * since we're only adjusting minutes and seconds, | |
37 | * don't interfere with hour overflow. This avoids | |
38 | * messing with unknown time zones but requires your | |
39 | * RTC not to be off by more than 15 minutes | |
40 | */ | |
41 | real_seconds = nowtime % 60; | |
42 | real_minutes = nowtime / 60; | |
43 | if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) | |
44 | real_minutes += 30; /* correct for half hour time zone */ | |
45 | real_minutes %= 60; | |
46 | ||
47 | if (abs(real_minutes - cmos_minutes) < 30) { | |
48 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { | |
49 | BIN_TO_BCD(real_seconds); | |
50 | BIN_TO_BCD(real_minutes); | |
51 | } | |
52 | CMOS_WRITE(real_seconds,RTC_SECONDS); | |
53 | CMOS_WRITE(real_minutes,RTC_MINUTES); | |
54 | } else { | |
55 | printk(KERN_WARNING | |
56 | "set_rtc_mmss: can't update from %d to %d\n", | |
57 | cmos_minutes, real_minutes); | |
58 | retval = -1; | |
59 | } | |
60 | ||
61 | /* The following flags have to be released exactly in this order, | |
62 | * otherwise the DS12887 (popular MC146818A clone with integrated | |
63 | * battery and quartz) will not reset the oscillator and will not | |
64 | * update precisely 500 ms later. You won't find this mentioned in | |
65 | * the Dallas Semiconductor data sheets, but who believes data | |
66 | * sheets anyway ... -- Markus Kuhn | |
67 | */ | |
68 | CMOS_WRITE(save_control, RTC_CONTROL); | |
69 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); | |
70 | ||
71 | return retval; | |
72 | } | |
73 | ||
fe599f9f | 74 | unsigned long mach_get_cmos_time(void) |
1da177e4 LT |
75 | { |
76 | unsigned int year, mon, day, hour, min, sec; | |
1da177e4 | 77 | |
63732c2f | 78 | do { |
1da177e4 LT |
79 | sec = CMOS_READ(RTC_SECONDS); |
80 | min = CMOS_READ(RTC_MINUTES); | |
81 | hour = CMOS_READ(RTC_HOURS); | |
82 | day = CMOS_READ(RTC_DAY_OF_MONTH); | |
83 | mon = CMOS_READ(RTC_MONTH); | |
84 | year = CMOS_READ(RTC_YEAR); | |
85 | } while (sec != CMOS_READ(RTC_SECONDS)); | |
63732c2f | 86 | |
41623b06 MM |
87 | if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
88 | BCD_TO_BIN(sec); | |
89 | BCD_TO_BIN(min); | |
90 | BCD_TO_BIN(hour); | |
91 | BCD_TO_BIN(day); | |
92 | BCD_TO_BIN(mon); | |
93 | BCD_TO_BIN(year); | |
94 | } | |
95 | ||
96 | year += 1900; | |
97 | if (year < 1970) | |
1da177e4 LT |
98 | year += 100; |
99 | ||
100 | return mktime(year, mon, day, hour, min, sec); | |
101 | } | |
102 | ||
fe599f9f TG |
103 | DEFINE_SPINLOCK(rtc_lock); |
104 | EXPORT_SYMBOL(rtc_lock); | |
105 | ||
106 | /* | |
107 | * This is a special lock that is owned by the CPU and holds the index | |
108 | * register we are working with. It is required for NMI access to the | |
109 | * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details. | |
110 | */ | |
111 | volatile unsigned long cmos_lock = 0; | |
112 | EXPORT_SYMBOL(cmos_lock); | |
113 | ||
114 | /* Routines for accessing the CMOS RAM/RTC. */ | |
115 | unsigned char rtc_cmos_read(unsigned char addr) | |
116 | { | |
117 | unsigned char val; | |
118 | ||
119 | lock_cmos_prefix(addr); | |
120 | outb_p(addr, RTC_PORT(0)); | |
121 | val = inb_p(RTC_PORT(1)); | |
122 | lock_cmos_suffix(addr); | |
123 | return val; | |
124 | } | |
125 | EXPORT_SYMBOL(rtc_cmos_read); | |
126 | ||
127 | void rtc_cmos_write(unsigned char val, unsigned char addr) | |
128 | { | |
129 | lock_cmos_prefix(addr); | |
130 | outb_p(addr, RTC_PORT(0)); | |
131 | outb_p(val, RTC_PORT(1)); | |
132 | lock_cmos_suffix(addr); | |
133 | } | |
134 | EXPORT_SYMBOL(rtc_cmos_write); | |
135 | ||
136 | static int set_rtc_mmss(unsigned long nowtime) | |
137 | { | |
138 | int retval; | |
139 | unsigned long flags; | |
140 | ||
141 | /* gets recalled with irq locally disabled */ | |
142 | /* XXX - does irqsave resolve this? -johnstul */ | |
143 | spin_lock_irqsave(&rtc_lock, flags); | |
144 | retval = set_wallclock(nowtime); | |
145 | spin_unlock_irqrestore(&rtc_lock, flags); | |
146 | ||
147 | return retval; | |
148 | } | |
149 | ||
150 | /* not static: needed by APM */ | |
151 | unsigned long read_persistent_clock(void) | |
152 | { | |
153 | unsigned long retval; | |
154 | unsigned long flags; | |
155 | ||
156 | spin_lock_irqsave(&rtc_lock, flags); | |
157 | retval = get_wallclock(); | |
158 | spin_unlock_irqrestore(&rtc_lock, flags); | |
159 | ||
160 | return retval; | |
161 | } | |
162 | ||
163 | int update_persistent_clock(struct timespec now) | |
164 | { | |
165 | return set_rtc_mmss(now.tv_sec); | |
166 | } |