1 /*
2 * RTC related functions
3 */
4 #include <linux/acpi.h>
5 #include <linux/bcd.h>
6 #include <linux/mc146818rtc.h>
7
8 #include <asm/time.h>
9 #include <asm/vsyscall.h>
10
11 #ifdef CONFIG_X86_32
12 # define CMOS_YEARS_OFFS 1900
13 /*
14 * This is a special lock that is owned by the CPU and holds the index
15 * register we are working with. It is required for NMI access to the
16 * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
17 */
18 volatile unsigned long cmos_lock = 0;
19 EXPORT_SYMBOL(cmos_lock);
20 #else
21 /*
22 * x86-64 systems only exists since 2002.
23 * This will work up to Dec 31, 2100
24 */
25 # define CMOS_YEARS_OFFS 2000
26 #endif
27
28 DEFINE_SPINLOCK(rtc_lock);
29 EXPORT_SYMBOL(rtc_lock);
30
31 /*
32 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
33 * called 500 ms after the second nowtime has started, because when
34 * nowtime is written into the registers of the CMOS clock, it will
35 * jump to the next second precisely 500 ms later. Check the Motorola
36 * MC146818A or Dallas DS12887 data sheet for details.
37 *
38 * BUG: This routine does not handle hour overflow properly; it just
39 * sets the minutes. Usually you'll only notice that after reboot!
40 */
41 int mach_set_rtc_mmss(unsigned long nowtime)
42 {
43 int retval = 0;
44 int real_seconds, real_minutes, cmos_minutes;
45 unsigned char save_control, save_freq_select;
46
47 /* tell the clock it's being set */
48 save_control = CMOS_READ(RTC_CONTROL);
49 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
50
51 /* stop and reset prescaler */
52 save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
53 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
54
55 cmos_minutes = CMOS_READ(RTC_MINUTES);
56 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
57 BCD_TO_BIN(cmos_minutes);
58
59 /*
60 * since we're only adjusting minutes and seconds,
61 * don't interfere with hour overflow. This avoids
62 * messing with unknown time zones but requires your
63 * RTC not to be off by more than 15 minutes
64 */
65 real_seconds = nowtime % 60;
66 real_minutes = nowtime / 60;
67 /* correct for half hour time zone */
68 if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
69 real_minutes += 30;
70 real_minutes %= 60;
71
72 if (abs(real_minutes - cmos_minutes) < 30) {
73 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
74 BIN_TO_BCD(real_seconds);
75 BIN_TO_BCD(real_minutes);
76 }
77 CMOS_WRITE(real_seconds,RTC_SECONDS);
78 CMOS_WRITE(real_minutes,RTC_MINUTES);
79 } else {
80 printk(KERN_WARNING
81 "set_rtc_mmss: can't update from %d to %d\n",
82 cmos_minutes, real_minutes);
83 retval = -1;
84 }
85
86 /* The following flags have to be released exactly in this order,
87 * otherwise the DS12887 (popular MC146818A clone with integrated
88 * battery and quartz) will not reset the oscillator and will not
89 * update precisely 500 ms later. You won't find this mentioned in
90 * the Dallas Semiconductor data sheets, but who believes data
91 * sheets anyway ... -- Markus Kuhn
92 */
93 CMOS_WRITE(save_control, RTC_CONTROL);
94 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
95
96 return retval;
97 }
98
99 unsigned long mach_get_cmos_time(void)
100 {
101 unsigned int year, mon, day, hour, min, sec, century = 0;
102
103 /*
104 * If UIP is clear, then we have >= 244 microseconds before
105 * RTC registers will be updated. Spec sheet says that this
106 * is the reliable way to read RTC - registers. If UIP is set
107 * then the register access might be invalid.
108 */
109 while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
110 cpu_relax();
111
112 sec = CMOS_READ(RTC_SECONDS);
113 min = CMOS_READ(RTC_MINUTES);
114 hour = CMOS_READ(RTC_HOURS);
115 day = CMOS_READ(RTC_DAY_OF_MONTH);
116 mon = CMOS_READ(RTC_MONTH);
117 year = CMOS_READ(RTC_YEAR);
118
119 #if defined(CONFIG_ACPI) && defined(CONFIG_X86_64)
120 /* CHECKME: Is this really 64bit only ??? */
121 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
122 acpi_gbl_FADT.century)
123 century = CMOS_READ(acpi_gbl_FADT.century);
124 #endif
125
126 if (RTC_ALWAYS_BCD || !(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)) {
127 BCD_TO_BIN(sec);
128 BCD_TO_BIN(min);
129 BCD_TO_BIN(hour);
130 BCD_TO_BIN(day);
131 BCD_TO_BIN(mon);
132 BCD_TO_BIN(year);
133 }
134
135 if (century) {
136 BCD_TO_BIN(century);
137 year += century * 100;
138 printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
139 } else {
140 year += CMOS_YEARS_OFFS;
141 if (year < 1970)
142 year += 100;
143 }
144
145 return mktime(year, mon, day, hour, min, sec);
146 }
147
148 /* Routines for accessing the CMOS RAM/RTC. */
149 unsigned char rtc_cmos_read(unsigned char addr)
150 {
151 unsigned char val;
152
153 lock_cmos_prefix(addr);
154 outb_p(addr, RTC_PORT(0));
155 val = inb_p(RTC_PORT(1));
156 lock_cmos_suffix(addr);
157 return val;
158 }
159 EXPORT_SYMBOL(rtc_cmos_read);
160
161 void rtc_cmos_write(unsigned char val, unsigned char addr)
162 {
163 lock_cmos_prefix(addr);
164 outb_p(addr, RTC_PORT(0));
165 outb_p(val, RTC_PORT(1));
166 lock_cmos_suffix(addr);
167 }
168 EXPORT_SYMBOL(rtc_cmos_write);
169
170 static int set_rtc_mmss(unsigned long nowtime)
171 {
172 int retval;
173 unsigned long flags;
174
175 spin_lock_irqsave(&rtc_lock, flags);
176 retval = set_wallclock(nowtime);
177 spin_unlock_irqrestore(&rtc_lock, flags);
178
179 return retval;
180 }
181
182 /* not static: needed by APM */
183 unsigned long read_persistent_clock(void)
184 {
185 unsigned long retval, flags;
186
187 spin_lock_irqsave(&rtc_lock, flags);
188 retval = get_wallclock();
189 spin_unlock_irqrestore(&rtc_lock, flags);
190
191 return retval;
192 }
193
194 int update_persistent_clock(struct timespec now)
195 {
196 return set_rtc_mmss(now.tv_sec);
197 }
198
199 unsigned long long native_read_tsc(void)
200 {
201 return __native_read_tsc();
202 }
203 EXPORT_SYMBOL(native_read_tsc);
204
205
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