diff options
Diffstat (limited to 'arch/mips/dec/time.c')
| -rw-r--r-- | arch/mips/dec/time.c | 163 |
1 files changed, 119 insertions, 44 deletions
diff --git a/arch/mips/dec/time.c b/arch/mips/dec/time.c index 151ce507e..0f3998557 100644 --- a/arch/mips/dec/time.c +++ b/arch/mips/dec/time.c @@ -1,8 +1,9 @@ /* - * linux/arch/mips/kernel/time.c + * linux/arch/mips/dec/time.c * * Copyright (C) 1991, 1992, 1995 Linus Torvalds + * Copyright (C) 2000 Maciej W. Rozycki * * This file contains the time handling details for PC-style clocks as * found in some MIPS systems. @@ -21,10 +22,15 @@ #include <asm/mipsregs.h> #include <asm/io.h> #include <asm/irq.h> +#include <asm/dec/machtype.h> +#include <asm/dec/ioasic.h> +#include <asm/dec/ioasic_addrs.h> #include <linux/mc146818rtc.h> #include <linux/timex.h> +#include <asm/div64.h> + extern volatile unsigned long wall_jiffies; extern rwlock_t xtime_lock; @@ -36,12 +42,22 @@ extern rwlock_t xtime_lock; /* This is for machines which generate the exact clock. */ #define USECS_PER_JIFFY (1000000/HZ) +#define USECS_PER_JIFFY_FRAC (0x100000000*1000000/HZ&0xffffffff) /* Cycle counter value at the previous timer interrupt.. */ static unsigned int timerhi = 0, timerlo = 0; /* + * Cached "1/(clocks per usec)*2^32" value. + * It has to be recalculated once each jiffy. + */ +static unsigned long cached_quotient = 0; + +/* Last jiffy when do_fast_gettimeoffset() was called. */ +static unsigned long last_jiffies = 0; + +/* * On MIPS only R4000 and better have a cycle counter. * * FIXME: Does playing with the RP bit in c0_status interfere with this code? @@ -50,45 +66,34 @@ static unsigned long do_fast_gettimeoffset(void) { u32 count; unsigned long res, tmp; - - /* Last jiffy when do_fast_gettimeoffset() was called. */ - static unsigned long last_jiffies = 0; unsigned long quotient; - /* - * Cached "1/(clocks per usec)*2^32" value. - * It has to be recalculated once each jiffy. - */ - static unsigned long cached_quotient = 0; - tmp = jiffies; quotient = cached_quotient; - if (tmp && last_jiffies != tmp) { - last_jiffies = tmp; - __asm__(".set\tnoreorder\n\t" - ".set\tnoat\n\t" - ".set\tmips3\n\t" - "lwu\t%0,%2\n\t" - "dsll32\t$1,%1,0\n\t" - "or\t$1,$1,%0\n\t" - "ddivu\t$0,$1,%3\n\t" - "mflo\t$1\n\t" - "dsll32\t%0,%4,0\n\t" - "nop\n\t" - "ddivu\t$0,%0,$1\n\t" - "mflo\t%0\n\t" - ".set\tmips0\n\t" - ".set\tat\n\t" - ".set\treorder" - :"=&r"(quotient) - :"r"(timerhi), - "m"(timerlo), - "r"(tmp), - "r"(USECS_PER_JIFFY) - :"$1"); + if (last_jiffies != tmp) { + last_jiffies = tmp; + if (last_jiffies != 0) { + unsigned long r0; + __asm__(".set push\n\t" + ".set mips3\n\t" + "lwu %0,%3\n\t" + "dsll32 %1,%2,0\n\t" + "or %1,%1,%0\n\t" + "ddivu $0,%1,%4\n\t" + "mflo %1\n\t" + "dsll32 %0,%5,0\n\t" + "or %0,%0,%6\n\t" + "ddivu $0,%0,%1\n\t" + "mflo %0\n\t" + ".set pop" + : "=&r" (quotient), "=&r" (r0) + : "r" (timerhi), "m" (timerlo), + "r" (tmp), "r" (USECS_PER_JIFFY), + "r" (USECS_PER_JIFFY_FRAC)); cached_quotient = quotient; + } } /* Get last timer tick in absolute kernel time */ count = read_32bit_cp0_register(CP0_COUNT); @@ -97,11 +102,9 @@ static unsigned long do_fast_gettimeoffset(void) count -= timerlo; //printk("count: %08lx, %08lx:%08lx\n", count, timerhi, timerlo); - __asm__("multu\t%1,%2\n\t" - "mfhi\t%0" - :"=r"(res) - :"r"(count), - "r"(quotient)); + __asm__("multu %2,%3" + : "=l" (tmp), "=h" (res) + : "r" (count), "r" (quotient)); /* * Due to possible jiffies inconsistencies, we need to check @@ -113,6 +116,47 @@ static unsigned long do_fast_gettimeoffset(void) return res; } +static unsigned long do_ioasic_gettimeoffset(void) +{ + u32 count; + unsigned long res, tmp; + unsigned long quotient; + + tmp = jiffies; + + quotient = cached_quotient; + + if (last_jiffies != tmp) { + last_jiffies = tmp; + if (last_jiffies != 0) { + unsigned long r0; + do_div64_32(r0, timerhi, timerlo, tmp); + do_div64_32(quotient, USECS_PER_JIFFY, + USECS_PER_JIFFY_FRAC, r0); + cached_quotient = quotient; + } + } + /* Get last timer tick in absolute kernel time */ + count = ioasic_read(FCTR); + + /* .. relative to previous jiffy (32 bits is enough) */ + count -= timerlo; +//printk("count: %08x, %08x:%08x\n", count, timerhi, timerlo); + + __asm__("multu %2,%3" + : "=l" (tmp), "=h" (res) + : "r" (count), "r" (quotient)); + + /* + * Due to possible jiffies inconsistencies, we need to check + * the result so that we'll get a timer that is monotonic. + */ + if (res >= USECS_PER_JIFFY) + res = USECS_PER_JIFFY - 1; + + return res; +} + /* This function must be called with interrupts disabled * It was inspired by Steve McCanne's microtime-i386 for BSD. -- jrs * @@ -170,8 +214,8 @@ void do_gettimeofday(struct timeval *tv) tv->tv_usec += do_gettimeoffset(); /* - * xtime is atomically updated in timer_bh. lost_ticks is - * nonzero if the timer bottom half hasnt executed yet. + * xtime is atomically updated in timer_bh. jiffies - wall_jiffies + * is nonzero if the timer bottom half hasnt executed yet. */ if (jiffies - wall_jiffies) tv->tv_usec += USECS_PER_JIFFY; @@ -309,11 +353,12 @@ timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) read_lock(&xtime_lock); if (time_state != TIME_BAD && xtime.tv_sec > last_rtc_update + 660 && xtime.tv_usec > 500000 - (tick >> 1) && - xtime.tv_usec < 500000 + (tick >> 1)) + xtime.tv_usec < 500000 + (tick >> 1)) { if (set_rtc_mmss(xtime.tv_sec) == 0) last_rtc_update = xtime.tv_sec; else last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */ + } /* As we return to user mode fire off the other CPU schedulers.. this is basically because we don't yet share IRQ's around. This message is rigged to be safe on the 386 - basically it's a hack, so don't look @@ -334,16 +379,42 @@ static void r4k_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) timerhi += (count < timerlo); /* Wrap around */ timerlo = count; + if (jiffies == ~0) { + /* + * If jiffies is to overflow in this timer_interrupt we must + * update the timer[hi]/[lo] to make do_fast_gettimeoffset() + * quotient calc still valid. -arca + */ + write_32bit_cp0_register(CP0_COUNT, 0); + timerhi = timerlo = 0; + } + timer_interrupt(irq, dev_id, regs); +} + +static void ioasic_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) +{ + unsigned int count; + + /* + * The free-running counter is 32 bit which is good for about + * 2 minutes, 50 seconds at possible count rates of upto 25MHz. + */ + count = ioasic_read(FCTR); + timerhi += (count < timerlo); /* Wrap around */ + timerlo = count; - if (!jiffies) { + if (jiffies == ~0) { /* - * If jiffies has overflowed in this timer_interrupt we must + * If jiffies is to overflow in this timer_interrupt we must * update the timer[hi]/[lo] to make do_fast_gettimeoffset() * quotient calc still valid. -arca */ + ioasic_write(FCTR, 0); timerhi = timerlo = 0; } + + timer_interrupt(irq, dev_id, regs); } /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. @@ -473,6 +544,10 @@ void __init time_init(void) write_32bit_cp0_register(CP0_COUNT, 0); do_gettimeoffset = do_fast_gettimeoffset; irq0.handler = r4k_timer_interrupt; - } + } else if (IOASIC) { + ioasic_write(FCTR, 0); + do_gettimeoffset = do_ioasic_gettimeoffset; + irq0.handler = ioasic_timer_interrupt; + } board_time_init(&irq0); } |