/*
* linux/include/asm-arm/arch-ebsa285/time.h
*
* Copyright (C) 1998 Russell King.
* Copyright (C) 1998 Phil Blundell
*
* CATS has a real-time clock, though the evaluation board doesn't.
*
* Changelog:
* 21-Mar-1998 RMK Created
* 27-Aug-1998 PJB CATS support
* 28-Dec-1998 APH Made leds optional
* 20-Jan-1999 RMK Started merge of EBSA285, CATS and NetWinder
* 16-Mar-1999 RMK More support for EBSA285-like machines with RTCs in
*/
#define RTC_PORT(x) (rtc_base+(x))
#define RTC_ALWAYS_BCD 0
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/mc146818rtc.h>
#include <linux/bcd.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/mach/time.h>
#include "common.h"
static int rtc_base;
static unsigned long __init get_isa_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
int i;
// check to see if the RTC makes sense.....
if ((CMOS_READ(RTC_VALID) & RTC_VRT) == 0)
return mktime(1970, 1, 1, 0, 0, 0);
/* 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);
}
if ((year += 1900) < 1970)
year += 100;
return mktime(year, mon, day, hour, min, sec);
}
static int set_isa_cmos_time(void)
{
int retval = 0;
int real_seconds, real_minutes, cmos_minutes;
unsigned char save_control, save_freq_select;
unsigned long nowtime = xtime.tv_sec;
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
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);
return retval;
}
void __init isa_rtc_init(void)
{
if (machine_is_co285() ||
machine_is_personal_server())
/*
* Add-in 21285s shouldn't access the RTC
*/
rtc_base = 0;
else
rtc_base = 0x70;
if (rtc_base) {
int reg_d, reg_b;
/*
* Probe for the RTC.
*/
reg_d = CMOS_READ(RTC_REG_D);
/*
* make sure the divider is set
*/
CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
/*
* Set control reg B
* (24 hour mode, update enabled)
*/
reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
reg_b |= 2;
CMOS_WRITE(reg_b, RTC_REG_B);
if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
CMOS_READ(RTC_REG_B) == reg_b) {
struct timespec tv;
/*
* We have a RTC. Check the battery
*/
if ((reg_d & 0x80) == 0)
printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
tv.tv_nsec = 0;
tv.tv_sec = get_isa_cmos_time();
do_settimeofday(&tv);
set_rtc = set_isa_cmos_time;
} else
rtc_base = 0;
}
}
