diff options
Diffstat (limited to 'arch/sh/boards/mpc1211/rtc.c')
| -rw-r--r-- | arch/sh/boards/mpc1211/rtc.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/arch/sh/boards/mpc1211/rtc.c b/arch/sh/boards/mpc1211/rtc.c new file mode 100644 index 00000000000..4d100f04807 --- /dev/null +++ b/arch/sh/boards/mpc1211/rtc.c @@ -0,0 +1,152 @@ +/* + * linux/arch/sh/kernel/rtc-mpc1211.c -- MPC-1211 on-chip RTC support + * + * Copyright (C) 2002 Saito.K & Jeanne + * + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/time.h> +#include <linux/mc146818rtc.h> + +#ifndef BCD_TO_BIN +#define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10) +#endif + +#ifndef BIN_TO_BCD +#define BIN_TO_BCD(val) ((val)=(((val)/10)<<4) + (val)%10) +#endif + +/* arc/i386/kernel/time.c */ +unsigned long get_cmos_time(void) +{ + unsigned int year, mon, day, hour, min, sec; + int i; + + spin_lock(&rtc_lock); + /* The Linux interpretation of the CMOS clock register contents: + * When the Update-In-Progress (UIP) flag goes from 1 to 0, the + * RTC registers show the second which has precisely just started. + * Let's hope other operating systems interpret the RTC the same way. + */ + /* read RTC exactly on falling edge of update flag */ + for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */ + if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) + break; + for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */ + if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)) + break; + do { /* Isn't this overkill ? UIP above should guarantee consistency */ + sec = CMOS_READ(RTC_SECONDS); + min = CMOS_READ(RTC_MINUTES); + hour = CMOS_READ(RTC_HOURS); + day = CMOS_READ(RTC_DAY_OF_MONTH); + mon = CMOS_READ(RTC_MONTH); + year = CMOS_READ(RTC_YEAR); + } while (sec != CMOS_READ(RTC_SECONDS)); + if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) + { + BCD_TO_BIN(sec); + BCD_TO_BIN(min); + BCD_TO_BIN(hour); + BCD_TO_BIN(day); + BCD_TO_BIN(mon); + BCD_TO_BIN(year); + } + spin_unlock(&rtc_lock); + if ((year += 1900) < 1970) + year += 100; + return mktime(year, mon, day, hour, min, sec); +} + +void mpc1211_rtc_gettimeofday(struct timeval *tv) +{ + + tv->tv_sec = get_cmos_time(); + tv->tv_usec = 0; +} + +/* arc/i386/kernel/time.c */ +/* + * In order to set the CMOS clock precisely, set_rtc_mmss has to be + * called 500 ms after the second nowtime has started, because when + * nowtime is written into the registers of the CMOS clock, it will + * jump to the next second precisely 500 ms later. Check the Motorola + * MC146818A or Dallas DS12887 data sheet for details. + * + * BUG: This routine does not handle hour overflow properly; it just + * sets the minutes. Usually you'll only notice that after reboot! + */ +static int set_rtc_mmss(unsigned long nowtime) +{ + int retval = 0; + int real_seconds, real_minutes, cmos_minutes; + unsigned char save_control, save_freq_select; + + /* gets recalled with irq locally disabled */ + spin_lock(&rtc_lock); + save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */ + CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); + + save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */ + CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); + + cmos_minutes = CMOS_READ(RTC_MINUTES); + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) + BCD_TO_BIN(cmos_minutes); + + /* + * since we're only adjusting minutes and seconds, + * don't interfere with hour overflow. This avoids + * messing with unknown time zones but requires your + * RTC not to be off by more than 15 minutes + */ + real_seconds = nowtime % 60; + real_minutes = nowtime / 60; + if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1) + real_minutes += 30; /* correct for half hour time zone */ + real_minutes %= 60; + + if (abs(real_minutes - cmos_minutes) < 30) { + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { + BIN_TO_BCD(real_seconds); + BIN_TO_BCD(real_minutes); + } + CMOS_WRITE(real_seconds,RTC_SECONDS); + CMOS_WRITE(real_minutes,RTC_MINUTES); + } else { + printk(KERN_WARNING + "set_rtc_mmss: can't update from %d to %d\n", + cmos_minutes, real_minutes); + retval = -1; + } + + /* The following flags have to be released exactly in this order, + * otherwise the DS12887 (popular MC146818A clone with integrated + * battery and quartz) will not reset the oscillator and will not + * update precisely 500 ms later. You won't find this mentioned in + * the Dallas Semiconductor data sheets, but who believes data + * sheets anyway ... -- Markus Kuhn + */ + CMOS_WRITE(save_control, RTC_CONTROL); + CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); + spin_unlock(&rtc_lock); + + return retval; +} + +int mpc1211_rtc_settimeofday(const struct timeval *tv) +{ + unsigned long nowtime = tv->tv_sec; + + return set_rtc_mmss(nowtime); +} + +void mpc1211_time_init(void) +{ + rtc_get_time = mpc1211_rtc_gettimeofday; + rtc_set_time = mpc1211_rtc_settimeofday; +} + |