xref: /openbmc/linux/arch/mips/dec/time.c (revision f42b3800)
1 /*
2  *  linux/arch/mips/dec/time.c
3  *
4  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
5  *  Copyright (C) 2000, 2003  Maciej W. Rozycki
6  *
7  * This file contains the time handling details for PC-style clocks as
8  * found in some MIPS systems.
9  *
10  */
11 #include <linux/bcd.h>
12 #include <linux/errno.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/kernel.h>
16 #include <linux/mc146818rtc.h>
17 #include <linux/mm.h>
18 #include <linux/module.h>
19 #include <linux/param.h>
20 #include <linux/sched.h>
21 #include <linux/string.h>
22 #include <linux/time.h>
23 #include <linux/types.h>
24 
25 #include <asm/bootinfo.h>
26 #include <asm/cpu.h>
27 #include <asm/io.h>
28 #include <asm/irq.h>
29 #include <asm/mipsregs.h>
30 #include <asm/sections.h>
31 #include <asm/time.h>
32 
33 #include <asm/dec/interrupts.h>
34 #include <asm/dec/ioasic.h>
35 #include <asm/dec/ioasic_addrs.h>
36 #include <asm/dec/machtype.h>
37 
38 unsigned long read_persistent_clock(void)
39 {
40 	unsigned int year, mon, day, hour, min, sec, real_year;
41 	unsigned long flags;
42 
43 	spin_lock_irqsave(&rtc_lock, flags);
44 
45 	do {
46 		sec = CMOS_READ(RTC_SECONDS);
47 		min = CMOS_READ(RTC_MINUTES);
48 		hour = CMOS_READ(RTC_HOURS);
49 		day = CMOS_READ(RTC_DAY_OF_MONTH);
50 		mon = CMOS_READ(RTC_MONTH);
51 		year = CMOS_READ(RTC_YEAR);
52 		/*
53 		 * The PROM will reset the year to either '72 or '73.
54 		 * Therefore we store the real year separately, in one
55 		 * of unused BBU RAM locations.
56 		 */
57 		real_year = CMOS_READ(RTC_DEC_YEAR);
58 	} while (sec != CMOS_READ(RTC_SECONDS));
59 
60 	spin_unlock_irqrestore(&rtc_lock, flags);
61 
62 	if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
63 		sec = BCD2BIN(sec);
64 		min = BCD2BIN(min);
65 		hour = BCD2BIN(hour);
66 		day = BCD2BIN(day);
67 		mon = BCD2BIN(mon);
68 		year = BCD2BIN(year);
69 	}
70 
71 	year += real_year - 72 + 2000;
72 
73 	return mktime(year, mon, day, hour, min, sec);
74 }
75 
76 /*
77  * In order to set the CMOS clock precisely, rtc_mips_set_mmss has to
78  * be called 500 ms after the second nowtime has started, because when
79  * nowtime is written into the registers of the CMOS clock, it will
80  * jump to the next second precisely 500 ms later.  Check the Dallas
81  * DS1287 data sheet for details.
82  */
83 int rtc_mips_set_mmss(unsigned long nowtime)
84 {
85 	int retval = 0;
86 	int real_seconds, real_minutes, cmos_minutes;
87 	unsigned char save_control, save_freq_select;
88 
89 	/* irq are locally disabled here */
90 	spin_lock(&rtc_lock);
91 	/* tell the clock it's being set */
92 	save_control = CMOS_READ(RTC_CONTROL);
93 	CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL);
94 
95 	/* stop and reset prescaler */
96 	save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
97 	CMOS_WRITE((save_freq_select | RTC_DIV_RESET2), RTC_FREQ_SELECT);
98 
99 	cmos_minutes = CMOS_READ(RTC_MINUTES);
100 	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
101 		cmos_minutes = BCD2BIN(cmos_minutes);
102 
103 	/*
104 	 * since we're only adjusting minutes and seconds,
105 	 * don't interfere with hour overflow. This avoids
106 	 * messing with unknown time zones but requires your
107 	 * RTC not to be off by more than 15 minutes
108 	 */
109 	real_seconds = nowtime % 60;
110 	real_minutes = nowtime / 60;
111 	if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
112 		real_minutes += 30;	/* correct for half hour time zone */
113 	real_minutes %= 60;
114 
115 	if (abs(real_minutes - cmos_minutes) < 30) {
116 		if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
117 			real_seconds = BIN2BCD(real_seconds);
118 			real_minutes = BIN2BCD(real_minutes);
119 		}
120 		CMOS_WRITE(real_seconds, RTC_SECONDS);
121 		CMOS_WRITE(real_minutes, RTC_MINUTES);
122 	} else {
123 		printk(KERN_WARNING
124 		       "set_rtc_mmss: can't update from %d to %d\n",
125 		       cmos_minutes, real_minutes);
126 		retval = -1;
127 	}
128 
129 	/* The following flags have to be released exactly in this order,
130 	 * otherwise the DS1287 will not reset the oscillator and will not
131 	 * update precisely 500 ms later.  You won't find this mentioned
132 	 * in the Dallas Semiconductor data sheets, but who believes data
133 	 * sheets anyway ...                           -- Markus Kuhn
134 	 */
135 	CMOS_WRITE(save_control, RTC_CONTROL);
136 	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
137 	spin_unlock(&rtc_lock);
138 
139 	return retval;
140 }
141 
142 static int dec_timer_state(void)
143 {
144 	return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
145 }
146 
147 static void dec_timer_ack(void)
148 {
149 	CMOS_READ(RTC_REG_C);			/* Ack the RTC interrupt.  */
150 }
151 
152 static cycle_t dec_ioasic_hpt_read(void)
153 {
154 	/*
155 	 * The free-running counter is 32-bit which is good for about
156 	 * 2 minutes, 50 seconds at possible count rates of up to 25MHz.
157 	 */
158 	return ioasic_read(IO_REG_FCTR);
159 }
160 
161 
162 void __init plat_time_init(void)
163 {
164 	mips_timer_ack = dec_timer_ack;
165 
166 	if (!cpu_has_counter && IOASIC)
167 		/* For pre-R4k systems we use the I/O ASIC's counter.  */
168 		clocksource_mips.read = dec_ioasic_hpt_read;
169 
170 	/* Set up the rate of periodic DS1287 interrupts.  */
171 	CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - __ffs(HZ)), RTC_REG_A);
172 }
173 
174 void __init plat_timer_setup(struct irqaction *irq)
175 {
176 	setup_irq(dec_interrupt[DEC_IRQ_RTC], irq);
177 
178 	/* Enable periodic DS1287 interrupts.  */
179 	CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B);
180 }
181