1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Copyright (C) 1991, 1992, 1995 Linus Torvalds |
4 | * Copyright (C) 2000, 2003 Maciej W. Rozycki |
5 | * |
6 | * This file contains the time handling details for PC-style clocks as |
7 | * found in some MIPS systems. |
8 | * |
9 | */ |
10 | #include <linux/bcd.h> |
11 | #include <linux/init.h> |
12 | #include <linux/mc146818rtc.h> |
13 | #include <linux/param.h> |
14 | |
15 | #include <asm/cpu-features.h> |
16 | #include <asm/ds1287.h> |
17 | #include <asm/time.h> |
18 | #include <asm/dec/interrupts.h> |
19 | #include <asm/dec/ioasic.h> |
20 | #include <asm/dec/machtype.h> |
21 | |
22 | void read_persistent_clock64(struct timespec64 *ts) |
23 | { |
24 | unsigned int year, mon, day, hour, min, sec, real_year; |
25 | unsigned long flags; |
26 | |
27 | spin_lock_irqsave(&rtc_lock, flags); |
28 | |
29 | do { |
30 | sec = CMOS_READ(RTC_SECONDS); |
31 | min = CMOS_READ(RTC_MINUTES); |
32 | hour = CMOS_READ(RTC_HOURS); |
33 | day = CMOS_READ(RTC_DAY_OF_MONTH); |
34 | mon = CMOS_READ(RTC_MONTH); |
35 | year = CMOS_READ(RTC_YEAR); |
36 | /* |
37 | * The PROM will reset the year to either '72 or '73. |
38 | * Therefore we store the real year separately, in one |
39 | * of unused BBU RAM locations. |
40 | */ |
41 | real_year = CMOS_READ(RTC_DEC_YEAR); |
42 | } while (sec != CMOS_READ(RTC_SECONDS)); |
43 | |
44 | spin_unlock_irqrestore(lock: &rtc_lock, flags); |
45 | |
46 | if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
47 | sec = bcd2bin(sec); |
48 | min = bcd2bin(min); |
49 | hour = bcd2bin(hour); |
50 | day = bcd2bin(day); |
51 | mon = bcd2bin(mon); |
52 | year = bcd2bin(year); |
53 | } |
54 | |
55 | year += real_year - 72 + 2000; |
56 | |
57 | ts->tv_sec = mktime64(year, mon, day, hour, min, sec); |
58 | ts->tv_nsec = 0; |
59 | } |
60 | |
61 | /* |
62 | * In order to set the CMOS clock precisely, update_persistent_clock64 has to |
63 | * be called 500 ms after the second nowtime has started, because when |
64 | * nowtime is written into the registers of the CMOS clock, it will |
65 | * jump to the next second precisely 500 ms later. Check the Dallas |
66 | * DS1287 data sheet for details. |
67 | */ |
68 | int update_persistent_clock64(struct timespec64 now) |
69 | { |
70 | time64_t nowtime = now.tv_sec; |
71 | int retval = 0; |
72 | int real_seconds, real_minutes, cmos_minutes; |
73 | unsigned char save_control, save_freq_select; |
74 | |
75 | /* irq are locally disabled here */ |
76 | spin_lock(lock: &rtc_lock); |
77 | /* tell the clock it's being set */ |
78 | save_control = CMOS_READ(RTC_CONTROL); |
79 | CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL); |
80 | |
81 | /* stop and reset prescaler */ |
82 | save_freq_select = CMOS_READ(RTC_FREQ_SELECT); |
83 | CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT); |
84 | |
85 | cmos_minutes = CMOS_READ(RTC_MINUTES); |
86 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) |
87 | cmos_minutes = bcd2bin(cmos_minutes); |
88 | |
89 | /* |
90 | * since we're only adjusting minutes and seconds, |
91 | * don't interfere with hour overflow. This avoids |
92 | * messing with unknown time zones but requires your |
93 | * RTC not to be off by more than 15 minutes |
94 | */ |
95 | real_minutes = div_s64_rem(dividend: nowtime, divisor: 60, remainder: &real_seconds); |
96 | if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) |
97 | real_minutes += 30; /* correct for half hour time zone */ |
98 | real_minutes %= 60; |
99 | |
100 | if (abs(real_minutes - cmos_minutes) < 30) { |
101 | if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { |
102 | real_seconds = bin2bcd(real_seconds); |
103 | real_minutes = bin2bcd(real_minutes); |
104 | } |
105 | CMOS_WRITE(real_seconds, RTC_SECONDS); |
106 | CMOS_WRITE(real_minutes, RTC_MINUTES); |
107 | } else { |
108 | printk_once(KERN_NOTICE |
109 | "set_rtc_mmss: can't update from %d to %d\n" , |
110 | cmos_minutes, real_minutes); |
111 | retval = -1; |
112 | } |
113 | |
114 | /* The following flags have to be released exactly in this order, |
115 | * otherwise the DS1287 will not reset the oscillator and will not |
116 | * update precisely 500 ms later. You won't find this mentioned |
117 | * in the Dallas Semiconductor data sheets, but who believes data |
118 | * sheets anyway ... -- Markus Kuhn |
119 | */ |
120 | CMOS_WRITE(save_control, RTC_CONTROL); |
121 | CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); |
122 | spin_unlock(lock: &rtc_lock); |
123 | |
124 | return retval; |
125 | } |
126 | |
127 | void __init plat_time_init(void) |
128 | { |
129 | int ioasic_clock = 0; |
130 | u32 start, end; |
131 | int i = HZ / 8; |
132 | |
133 | /* Set up the rate of periodic DS1287 interrupts. */ |
134 | ds1287_set_base_clock(HZ); |
135 | |
136 | /* On some I/O ASIC systems we have the I/O ASIC's counter. */ |
137 | if (IOASIC) |
138 | ioasic_clock = dec_ioasic_clocksource_init() == 0; |
139 | if (cpu_has_counter) { |
140 | ds1287_timer_state(); |
141 | while (!ds1287_timer_state()) |
142 | ; |
143 | |
144 | start = read_c0_count(); |
145 | |
146 | while (i--) |
147 | while (!ds1287_timer_state()) |
148 | ; |
149 | |
150 | end = read_c0_count(); |
151 | |
152 | mips_hpt_frequency = (end - start) * 8; |
153 | printk(KERN_INFO "MIPS counter frequency %dHz\n" , |
154 | mips_hpt_frequency); |
155 | |
156 | /* |
157 | * All R4k DECstations suffer from the CP0 Count erratum, |
158 | * so we can't use the timer as a clock source, and a clock |
159 | * event both at a time. An accurate wall clock is more |
160 | * important than a high-precision interval timer so only |
161 | * use the timer as a clock source, and not a clock event |
162 | * if there's no I/O ASIC counter available to serve as a |
163 | * clock source. |
164 | */ |
165 | if (!ioasic_clock) { |
166 | init_r4k_clocksource(); |
167 | mips_hpt_frequency = 0; |
168 | } |
169 | } |
170 | |
171 | ds1287_clockevent_init(dec_interrupt[DEC_IRQ_RTC]); |
172 | } |
173 | |