diff options
Diffstat (limited to 'arch/mips/dec/time.c')
| -rw-r--r-- | arch/mips/dec/time.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c new file mode 100644 index 00000000000..dc7091caa7a --- /dev/null +++ b/arch/mips/dec/time.c @@ -0,0 +1,200 @@ +/* + * linux/arch/mips/dec/time.c + * + * Copyright (C) 1991, 1992, 1995 Linus Torvalds + * Copyright (C) 2000, 2003 Maciej W. Rozycki + * + * This file contains the time handling details for PC-style clocks as + * found in some MIPS systems. + * + */ +#include <linux/bcd.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/mc146818rtc.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/param.h> +#include <linux/sched.h> +#include <linux/string.h> +#include <linux/time.h> +#include <linux/types.h> + +#include <asm/bootinfo.h> +#include <asm/cpu.h> +#include <asm/div64.h> +#include <asm/io.h> +#include <asm/irq.h> +#include <asm/mipsregs.h> +#include <asm/sections.h> +#include <asm/time.h> + +#include <asm/dec/interrupts.h> +#include <asm/dec/ioasic.h> +#include <asm/dec/ioasic_addrs.h> +#include <asm/dec/machtype.h> + + +static unsigned long dec_rtc_get_time(void) +{ + unsigned int year, mon, day, hour, min, sec, real_year; + int i; + + /* The Linux interpretation of the DS1287 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; + /* Isn't this overkill? UIP above should guarantee consistency */ + do { + 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) { + sec = BCD2BIN(sec); + min = BCD2BIN(min); + hour = BCD2BIN(hour); + day = BCD2BIN(day); + mon = BCD2BIN(mon); + year = BCD2BIN(year); + } + /* + * The PROM will reset the year to either '72 or '73. + * Therefore we store the real year separately, in one + * of unused BBU RAM locations. + */ + real_year = CMOS_READ(RTC_DEC_YEAR); + year += real_year - 72 + 2000; + + return mktime(year, mon, day, hour, min, sec); +} + +/* + * In order to set the CMOS clock precisely, dec_rtc_set_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 Dallas + * DS1287 data sheet for details. + */ +static int dec_rtc_set_mmss(unsigned long nowtime) +{ + int retval = 0; + int real_seconds, real_minutes, cmos_minutes; + unsigned char save_control, save_freq_select; + + /* tell the clock it's being set */ + save_control = CMOS_READ(RTC_CONTROL); + CMOS_WRITE((save_control | RTC_SET), RTC_CONTROL); + + /* stop and reset prescaler */ + save_freq_select = CMOS_READ(RTC_FREQ_SELECT); + 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) + cmos_minutes = BCD2BIN(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) { + real_seconds = BIN2BCD(real_seconds); + real_minutes = BIN2BCD(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 DS1287 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; +} + + +static int dec_timer_state(void) +{ + return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0; +} + +static void dec_timer_ack(void) +{ + CMOS_READ(RTC_REG_C); /* Ack the RTC interrupt. */ +} + +static unsigned int dec_ioasic_hpt_read(void) +{ + /* + * The free-running counter is 32-bit which is good for about + * 2 minutes, 50 seconds at possible count rates of up to 25MHz. + */ + return ioasic_read(IO_REG_FCTR); +} + +static void dec_ioasic_hpt_init(unsigned int count) +{ + ioasic_write(IO_REG_FCTR, ioasic_read(IO_REG_FCTR) - count); +} + + +void __init dec_time_init(void) +{ + rtc_get_time = dec_rtc_get_time; + rtc_set_mmss = dec_rtc_set_mmss; + + mips_timer_state = dec_timer_state; + mips_timer_ack = dec_timer_ack; + + if (!cpu_has_counter && IOASIC) { + /* For pre-R4k systems we use the I/O ASIC's counter. */ + mips_hpt_read = dec_ioasic_hpt_read; + mips_hpt_init = dec_ioasic_hpt_init; + } + + /* Set up the rate of periodic DS1287 interrupts. */ + CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - LOG_2_HZ), RTC_REG_A); +} + +EXPORT_SYMBOL(do_settimeofday); + +void __init dec_timer_setup(struct irqaction *irq) +{ + setup_irq(dec_interrupt[DEC_IRQ_RTC], irq); + + /* Enable periodic DS1287 interrupts. */ + CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B); +} |