/*
* arch/ppc64/kernel/maple_time.c
*
* (c) Copyright 2004 Benjamin Herrenschmidt (benh@kernel.crashing.org),
* IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*/
#undef DEBUG
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/adb.h>
#include <linux/pmu.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/bcd.h>
#include <asm/sections.h>
#include <asm/prom.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/machdep.h>
#include <asm/time.h>
#ifdef DEBUG
#define DBG(x...) printk(x)
#else
#define DBG(x...)
#endif
extern void GregorianDay(struct rtc_time * tm);
static int maple_rtc_addr;
static int maple_clock_read(int addr)
{
outb_p(addr, maple_rtc_addr);
return inb_p(maple_rtc_addr+1);
}
static void maple_clock_write(unsigned long val, int addr)
{
outb_p(addr, maple_rtc_addr);
outb_p(val, maple_rtc_addr+1);
}
void maple_get_rtc_time(struct rtc_time *tm)
{
int uip, i;
/* 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.
*/
/* Since the UIP flag is set for about 2.2 ms and the clock
* is typically written with a precision of 1 jiffy, trying
* to obtain a precision better than a few milliseconds is
* an illusion. Only consistency is interesting, this also
* allows to use the routine for /dev/rtc without a potential
* 1 second kernel busy loop triggered by any reader of /dev/rtc.
*/
for (i = 0; i<1000000; i++) {
uip = maple_clock_read(RTC_FREQ_SELECT);
tm->tm_sec = maple_clock_read(RTC_SECONDS);
tm->tm_min = maple_clock_read(RTC_MINUTES);
tm->tm_hour = maple_clock_read(RTC_HOURS);
tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
tm->tm_mon = maple_clock_read(RTC_MONTH);
tm->tm_year = maple_clock_read(RTC_YEAR);
uip |= maple_clock_read(RTC_FREQ_SELECT);
if ((uip & RTC_UIP)==0)
break;
}
if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
|| RTC_ALWAYS_BCD) {
BCD_TO_BIN(tm->tm_sec);
BCD_TO_BIN(tm->tm_min);
BCD_TO_BIN(tm->tm_hour);
BCD_TO_BIN(tm->tm_mday);
BCD_TO_BIN(tm->tm_mon);
BCD_TO_BIN(tm->tm_year);
}
if ((tm->tm_year + 1900) < 1970)
tm->tm_year += 100;
GregorianDay(tm);
}
int maple_set_rtc_time(struct rtc_time *tm)
{
unsigned char save_control, save_freq_select;
int sec, min, hour, mon, mday, year;
spin_lock(&rtc_lock);
save_control = maple_clock_read(RTC_CONTROL); /* tell the clock it's being set */
maple_clock_write((save_control|RTC_SET), RTC_CONTROL);
save_freq_select = maple_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
maple_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
sec = tm->tm_sec;
min = tm->tm_min;
hour = tm->tm_hour;
mon = tm->tm_mon;
mday = tm->tm_mday;
year = tm->tm_year;
if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
BIN_TO_BCD(sec);
BIN_TO_BCD(min);
BIN_TO_BCD(hour);
BIN_TO_BCD(mon);
BIN_TO_BCD(mday);
BIN_TO_BCD(year);
}
maple_clock_write(sec, RTC_SECONDS);
maple_clock_write(min, RTC_MINUTES);
maple_clock_write(hour, RTC_HOURS);
maple_clock_write(mon, RTC_MONTH);
maple_clock_write(mday, RTC_DAY_OF_MONTH);
maple_clock_write(year, RTC_YEAR);
/* 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
*/
maple_clock_write(save_control, RTC_CONTROL);
maple_clock_write(save_freq_select, RTC_FREQ_SELECT);
spin_unlock(&rtc_lock);
return 0;
}
void __init maple_get_boot_time(struct rtc_time *tm)
{
struct device_node *rtcs;
rtcs = find_compatible_devices("rtc", "pnpPNP,b00");
if (rtcs && rtcs->addrs) {
maple_rtc_addr = rtcs->addrs[0].address;
printk(KERN_INFO "Maple: Found RTC at 0x%x\n", maple_rtc_addr);
} else {
maple_rtc_addr = RTC_PORT(0); /* legacy address */
printk(KERN_INFO "Maple: No device node for RTC, assuming "
"legacy address (0x%x)\n", maple_rtc_addr);
}
maple_get_rtc_time(tm);
}
