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b920de1b DH |
1 | /* MN10300 RTC management |
2 | * | |
3 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/mc146818rtc.h> | |
15 | #include <linux/bcd.h> | |
16 | #include <linux/timex.h> | |
17 | #include <asm/rtc-regs.h> | |
18 | #include <asm/rtc.h> | |
19 | ||
20 | DEFINE_SPINLOCK(rtc_lock); | |
21 | EXPORT_SYMBOL(rtc_lock); | |
22 | ||
b920de1b DH |
23 | /* time for RTC to update itself in ioclks */ |
24 | static unsigned long mn10300_rtc_update_period; | |
25 | ||
f7a56575 | 26 | void read_persistent_clock(struct timespec *ts) |
b920de1b DH |
27 | { |
28 | struct rtc_time tm; | |
29 | ||
30 | get_rtc_time(&tm); | |
31 | ||
f7a56575 | 32 | ts->tv_sec = mktime(tm.tm_year, tm.tm_mon, tm.tm_mday, |
b920de1b | 33 | tm.tm_hour, tm.tm_min, tm.tm_sec); |
f7a56575 | 34 | ts->tv_nsec = 0; |
b920de1b DH |
35 | } |
36 | ||
37 | /* | |
38 | * In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500 | |
39 | * ms after the second nowtime has started, because when nowtime is written | |
40 | * into the registers of the CMOS clock, it will jump to the next second | |
41 | * precisely 500 ms later. Check the Motorola MC146818A or Dallas DS12887 data | |
42 | * sheet for details. | |
43 | * | |
44 | * BUG: This routine does not handle hour overflow properly; it just | |
45 | * sets the minutes. Usually you'll only notice that after reboot! | |
46 | */ | |
47 | static int set_rtc_mmss(unsigned long nowtime) | |
48 | { | |
49 | unsigned char save_control, save_freq_select; | |
50 | int retval = 0; | |
51 | int real_seconds, real_minutes, cmos_minutes; | |
52 | ||
53 | /* gets recalled with irq locally disabled */ | |
54 | spin_lock(&rtc_lock); | |
55 | save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being | |
56 | * set */ | |
57 | CMOS_WRITE(save_control | RTC_SET, RTC_CONTROL); | |
58 | ||
59 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset | |
60 | * prescaler */ | |
61 | CMOS_WRITE(save_freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT); | |
62 | ||
63 | cmos_minutes = CMOS_READ(RTC_MINUTES); | |
64 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) | |
f6a2298c | 65 | cmos_minutes = bcd2bin(cmos_minutes); |
b920de1b DH |
66 | |
67 | /* | |
68 | * since we're only adjusting minutes and seconds, | |
69 | * don't interfere with hour overflow. This avoids | |
70 | * messing with unknown time zones but requires your | |
71 | * RTC not to be off by more than 15 minutes | |
72 | */ | |
73 | real_seconds = nowtime % 60; | |
74 | real_minutes = nowtime / 60; | |
75 | if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) | |
76 | /* correct for half hour time zone */ | |
77 | real_minutes += 30; | |
78 | real_minutes %= 60; | |
79 | ||
80 | if (abs(real_minutes - cmos_minutes) < 30) { | |
81 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { | |
f6a2298c AB |
82 | real_seconds = bin2bcd(real_seconds); |
83 | real_minutes = bin2bcd(real_minutes); | |
b920de1b DH |
84 | } |
85 | CMOS_WRITE(real_seconds, RTC_SECONDS); | |
86 | CMOS_WRITE(real_minutes, RTC_MINUTES); | |
87 | } else { | |
88 | printk(KERN_WARNING | |
89 | "set_rtc_mmss: can't update from %d to %d\n", | |
90 | cmos_minutes, real_minutes); | |
91 | retval = -1; | |
92 | } | |
93 | ||
94 | /* The following flags have to be released exactly in this order, | |
95 | * otherwise the DS12887 (popular MC146818A clone with integrated | |
96 | * battery and quartz) will not reset the oscillator and will not | |
97 | * update precisely 500 ms later. You won't find this mentioned in | |
98 | * the Dallas Semiconductor data sheets, but who believes data | |
99 | * sheets anyway ... -- Markus Kuhn | |
100 | */ | |
101 | CMOS_WRITE(save_control, RTC_CONTROL); | |
102 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); | |
103 | spin_unlock(&rtc_lock); | |
104 | ||
105 | return retval; | |
106 | } | |
107 | ||
f7a56575 | 108 | int update_persistent_clock(struct timespec now) |
b920de1b | 109 | { |
35579576 | 110 | return set_rtc_mmss(now.tv_sec); |
b920de1b DH |
111 | } |
112 | ||
113 | /* | |
114 | * calibrate the TSC clock against the RTC | |
115 | */ | |
116 | void __init calibrate_clock(void) | |
117 | { | |
118 | unsigned long count0, counth, count1; | |
119 | unsigned char status; | |
120 | ||
121 | /* make sure the RTC is running and is set to operate in 24hr mode */ | |
122 | status = RTSRC; | |
123 | RTCRB |= RTCRB_SET; | |
124 | RTCRB |= RTCRB_TM_24HR; | |
125 | RTCRA |= RTCRA_DVR; | |
126 | RTCRA &= ~RTCRA_DVR; | |
127 | RTCRB &= ~RTCRB_SET; | |
128 | ||
129 | /* work out the clock speed by counting clock cycles between ends of | |
130 | * the RTC update cycle - track the RTC through one complete update | |
131 | * cycle (1 second) | |
132 | */ | |
133 | startup_timestamp_counter(); | |
134 | ||
135 | while (!(RTCRA & RTCRA_UIP)) {} | |
136 | while ((RTCRA & RTCRA_UIP)) {} | |
137 | ||
138 | count0 = TMTSCBC; | |
139 | ||
140 | while (!(RTCRA & RTCRA_UIP)) {} | |
141 | ||
142 | counth = TMTSCBC; | |
143 | ||
144 | while ((RTCRA & RTCRA_UIP)) {} | |
145 | ||
146 | count1 = TMTSCBC; | |
147 | ||
148 | shutdown_timestamp_counter(); | |
149 | ||
150 | MN10300_TSCCLK = count0 - count1; /* the timers count down */ | |
151 | mn10300_rtc_update_period = counth - count1; | |
152 | MN10300_TSC_PER_HZ = MN10300_TSCCLK / HZ; | |
153 | } |