diff options
Diffstat (limited to 'arch/powerpc/platforms/maple/time.c')
| -rw-r--r-- | arch/powerpc/platforms/maple/time.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/maple/time.c b/arch/powerpc/platforms/maple/time.c new file mode 100644 index 00000000000..40fc07a8e60 --- /dev/null +++ b/arch/powerpc/platforms/maple/time.c @@ -0,0 +1,180 @@ +/* + * 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> + +#include "maple.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; +} + +unsigned long __init maple_get_boot_time(void) +{ + 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); + return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday, + tm.tm_hour, tm.tm_min, tm.tm_sec); +} + |