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Source at commit 694c7fbe86b8a9c91392e505afcb9fcfc91deccc created 13 years 12 days ago. By Maarten ter Huurne, MIPS: JZ4740: Add cpufreq support | |
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1 | /* |
2 | * Copyright (C) 1991, 1992, 1995 Linus Torvalds |
3 | * Copyright (C) 2000, 2003 Maciej W. Rozycki |
4 | * |
5 | * This file contains the time handling details for PC-style clocks as |
6 | * found in some MIPS systems. |
7 | * |
8 | */ |
9 | #include <linux/bcd.h> |
10 | #include <linux/init.h> |
11 | #include <linux/mc146818rtc.h> |
12 | #include <linux/param.h> |
13 | |
14 | #include <asm/cpu-features.h> |
15 | #include <asm/ds1287.h> |
16 | #include <asm/time.h> |
17 | #include <asm/dec/interrupts.h> |
18 | #include <asm/dec/ioasic.h> |
19 | #include <asm/dec/machtype.h> |
20 | |
21 | void read_persistent_clock(struct timespec *ts) |
22 | { |
23 | unsigned int year, mon, day, hour, min, sec, real_year; |
24 | unsigned long flags; |
25 | |
26 | spin_lock_irqsave(&rtc_lock, flags); |
27 | |
28 | do { |
29 | sec = CMOS_READ(RTC_SECONDS); |
30 | min = CMOS_READ(RTC_MINUTES); |
31 | hour = CMOS_READ(RTC_HOURS); |
32 | day = CMOS_READ(RTC_DAY_OF_MONTH); |
33 | mon = CMOS_READ(RTC_MONTH); |
34 | year = CMOS_READ(RTC_YEAR); |
35 | /* |
36 | * The PROM will reset the year to either '72 or '73. |
37 | * Therefore we store the real year separately, in one |
38 | * of unused BBU RAM locations. |
39 | */ |
40 | real_year = CMOS_READ(RTC_DEC_YEAR); |
41 | } while (sec != CMOS_READ(RTC_SECONDS)); |
42 | |
43 | spin_unlock_irqrestore(&rtc_lock, flags); |
44 | |
45 | if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
46 | sec = bcd2bin(sec); |
47 | min = bcd2bin(min); |
48 | hour = bcd2bin(hour); |
49 | day = bcd2bin(day); |
50 | mon = bcd2bin(mon); |
51 | year = bcd2bin(year); |
52 | } |
53 | |
54 | year += real_year - 72 + 2000; |
55 | |
56 | ts->tv_sec = mktime(year, mon, day, hour, min, sec); |
57 | ts->tv_nsec = 0; |
58 | } |
59 | |
60 | /* |
61 | * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to |
62 | * be called 500 ms after the second nowtime has started, because when |
63 | * nowtime is written into the registers of the CMOS clock, it will |
64 | * jump to the next second precisely 500 ms later. Check the Dallas |
65 | * DS1287 data sheet for details. |
66 | */ |
67 | int rtc_mips_set_mmss(unsigned long nowtime) |
68 | { |
69 | int retval = 0; |
70 | int real_seconds, real_minutes, cmos_minutes; |
71 | unsigned char save_control, save_freq_select; |
72 | |
73 | /* irq are locally disabled here */ |
74 | spin_lock(&rtc_lock); |
75 | /* tell the clock it's being set */ |
76 | save_control = CMOS_READ(RTC_CONTROL); |
77 | CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL); |
78 | |
79 | /* stop and reset prescaler */ |
80 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); |
81 | CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT); |
82 | |
83 | cmos_minutes = CMOS_READ(RTC_MINUTES); |
84 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) |
85 | cmos_minutes = bcd2bin(cmos_minutes); |
86 | |
87 | /* |
88 | * since we're only adjusting minutes and seconds, |
89 | * don't interfere with hour overflow. This avoids |
90 | * messing with unknown time zones but requires your |
91 | * RTC not to be off by more than 15 minutes |
92 | */ |
93 | real_seconds = nowtime % 60; |
94 | real_minutes = nowtime / 60; |
95 | if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) |
96 | real_minutes += 30; /* correct for half hour time zone */ |
97 | real_minutes %= 60; |
98 | |
99 | if (abs(real_minutes - cmos_minutes) < 30) { |
100 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
101 | real_seconds = bin2bcd(real_seconds); |
102 | real_minutes = bin2bcd(real_minutes); |
103 | } |
104 | CMOS_WRITE(real_seconds, RTC_SECONDS); |
105 | CMOS_WRITE(real_minutes, RTC_MINUTES); |
106 | } else { |
107 | printk_once(KERN_NOTICE |
108 | "set_rtc_mmss: can't update from %d to %d\n", |
109 | cmos_minutes, real_minutes); |
110 | retval = -1; |
111 | } |
112 | |
113 | /* The following flags have to be released exactly in this order, |
114 | * otherwise the DS1287 will not reset the oscillator and will not |
115 | * update precisely 500 ms later. You won't find this mentioned |
116 | * in the Dallas Semiconductor data sheets, but who believes data |
117 | * sheets anyway ... -- Markus Kuhn |
118 | */ |
119 | CMOS_WRITE(save_control, RTC_CONTROL); |
120 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); |
121 | spin_unlock(&rtc_lock); |
122 | |
123 | return retval; |
124 | } |
125 | |
126 | void __init plat_time_init(void) |
127 | { |
128 | int ioasic_clock = 0; |
129 | u32 start, end; |
130 | int i = HZ / 8; |
131 | |
132 | /* Set up the rate of periodic DS1287 interrupts. */ |
133 | ds1287_set_base_clock(HZ); |
134 | |
135 | /* On some I/O ASIC systems we have the I/O ASIC's counter. */ |
136 | if (IOASIC) |
137 | ioasic_clock = dec_ioasic_clocksource_init() == 0; |
138 | if (cpu_has_counter) { |
139 | ds1287_timer_state(); |
140 | while (!ds1287_timer_state()) |
141 | ; |
142 | |
143 | start = read_c0_count(); |
144 | |
145 | while (i--) |
146 | while (!ds1287_timer_state()) |
147 | ; |
148 | |
149 | end = read_c0_count(); |
150 | |
151 | mips_hpt_frequency = (end - start) * 8; |
152 | printk(KERN_INFO "MIPS counter frequency %dHz\n", |
153 | mips_hpt_frequency); |
154 | |
155 | /* |
156 | * All R4k DECstations suffer from the CP0 Count erratum, |
157 | * so we can't use the timer as a clock source, and a clock |
158 | * event both at a time. An accurate wall clock is more |
159 | * important than a high-precision interval timer so only |
160 | * use the timer as a clock source, and not a clock event |
161 | * if there's no I/O ASIC counter available to serve as a |
162 | * clock source. |
163 | */ |
164 | if (!ioasic_clock) { |
165 | init_r4k_clocksource(); |
166 | mips_hpt_frequency = 0; |
167 | } |
168 | } |
169 | |
170 | ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]); |
171 | } |
172 |
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v2.6.34-rc5
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