tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * linux/arch/sh/kernel/rtc-mpc1211.c -- MPC-1211 on-chip RTC support
3 *
4 * Copyright (C) 2002 Saito.K & Jeanne
5 *
6 */
7
8#include <linux/init.h>
9#include <linux/kernel.h>
10#include <linux/sched.h>
11#include <linux/time.h>
12#include <linux/bcd.h>
13#include <linux/mc146818rtc.h>
14
15unsigned long get_cmos_time(void)
16{
17 unsigned int year, mon, day, hour, min, sec;
18
19 spin_lock(&rtc_lock);
20
21 do {
22 sec = CMOS_READ(RTC_SECONDS);
23 min = CMOS_READ(RTC_MINUTES);
24 hour = CMOS_READ(RTC_HOURS);
25 day = CMOS_READ(RTC_DAY_OF_MONTH);
26 mon = CMOS_READ(RTC_MONTH);
27 year = CMOS_READ(RTC_YEAR);
28 } while (sec != CMOS_READ(RTC_SECONDS));
29
30 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
31 BCD_TO_BIN(sec);
32 BCD_TO_BIN(min);
33 BCD_TO_BIN(hour);
34 BCD_TO_BIN(day);
35 BCD_TO_BIN(mon);
36 BCD_TO_BIN(year);
37 }
38
39 spin_unlock(&rtc_lock);
40
41 year += 1900;
42 if (year < 1970)
43 year += 100;
44
45 return mktime(year, mon, day, hour, min, sec);
46}
47
48void mpc1211_rtc_gettimeofday(struct timeval *tv)
49{
50
51 tv->tv_sec = get_cmos_time();
52 tv->tv_usec = 0;
53}
54
55/* arc/i386/kernel/time.c */
56/*
57 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
58 * called 500 ms after the second nowtime has started, because when
59 * nowtime is written into the registers of the CMOS clock, it will
60 * jump to the next second precisely 500 ms later. Check the Motorola
61 * MC146818A or Dallas DS12887 data sheet for details.
62 *
63 * BUG: This routine does not handle hour overflow properly; it just
64 * sets the minutes. Usually you'll only notice that after reboot!
65 */
66static int set_rtc_mmss(unsigned long nowtime)
67{
68 int retval = 0;
69 int real_seconds, real_minutes, cmos_minutes;
70 unsigned char save_control, save_freq_select;
71
72 /* gets recalled with irq locally disabled */
73 spin_lock(&rtc_lock);
74 save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
75 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
76
77 save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
78 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
79
80 cmos_minutes = CMOS_READ(RTC_MINUTES);
81 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
82 BCD_TO_BIN(cmos_minutes);
83
84 /*
85 * since we're only adjusting minutes and seconds,
86 * don't interfere with hour overflow. This avoids
87 * messing with unknown time zones but requires your
88 * RTC not to be off by more than 15 minutes
89 */
90 real_seconds = nowtime % 60;
91 real_minutes = nowtime / 60;
92 if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
93 real_minutes += 30; /* correct for half hour time zone */
94 real_minutes %= 60;
95
96 if (abs(real_minutes - cmos_minutes) < 30) {
97 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
98 BIN_TO_BCD(real_seconds);
99 BIN_TO_BCD(real_minutes);
100 }
101 CMOS_WRITE(real_seconds,RTC_SECONDS);
102 CMOS_WRITE(real_minutes,RTC_MINUTES);
103 } else {
104 printk(KERN_WARNING
105 "set_rtc_mmss: can't update from %d to %d\n",
106 cmos_minutes, real_minutes);
107 retval = -1;
108 }
109
110 /* The following flags have to be released exactly in this order,
111 * otherwise the DS12887 (popular MC146818A clone with integrated
112 * battery and quartz) will not reset the oscillator and will not
113 * update precisely 500 ms later. You won't find this mentioned in
114 * the Dallas Semiconductor data sheets, but who believes data
115 * sheets anyway ... -- Markus Kuhn
116 */
117 CMOS_WRITE(save_control, RTC_CONTROL);
118 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
119 spin_unlock(&rtc_lock);
120
121 return retval;
122}
123
124int mpc1211_rtc_settimeofday(const struct timeval *tv)
125{
126 unsigned long nowtime = tv->tv_sec;
127
128 return set_rtc_mmss(nowtime);
129}
130
131void mpc1211_time_init(void)
132{
133 rtc_sh_get_time = mpc1211_rtc_gettimeofday;
134 rtc_sh_set_time = mpc1211_rtc_settimeofday;
135}
136