diff options
| author | Ralf Baechle <ralf@linux-mips.org> | 1998-03-11 15:21:44 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 1998-03-11 15:21:44 +0000 |
| commit | 6a76fb7214c477ccf6582bd79c5b4ccc4f9c41b1 (patch) | |
| tree | fe544bf249c9093fdb94ea1bdf0a2af1acd3659e /arch/mips/sgi/kernel/indy_timer.c | |
| parent | c76e7d2fb3e85821ba1842d4f5219283eb706544 (diff) | |
Timer code rework. Done so far:
o Fix interrupt handler to not loose cycles
o Warn about lost interrupts.
o Fix calibration of the R4000 CPU timer.
Still to do:
o General cleanup of the timer code
o Microsecond timers for the Indy
o The calculated values for r4k_offset are still off by ~480 from the
theoretical values. That means we're going to loose about 46 s per
day. Are the crystals that bad or is there still a bug hidden
somewhere? Maybe an option to set r4k_offset to a user supplied
value might help?
o Handle lost interrupts more gently so we don't loose time.
o Handle 100MHz R4000 count / compare bug.
Diffstat (limited to 'arch/mips/sgi/kernel/indy_timer.c')
| -rw-r--r-- | arch/mips/sgi/kernel/indy_timer.c | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/arch/mips/sgi/kernel/indy_timer.c b/arch/mips/sgi/kernel/indy_timer.c index 4b7bfd941..69b5ea062 100644 --- a/arch/mips/sgi/kernel/indy_timer.c +++ b/arch/mips/sgi/kernel/indy_timer.c @@ -3,7 +3,7 @@ * * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com) * - * $Id: indy_timer.c,v 1.3 1997/08/11 04:37:09 ralf Exp $ + * $Id: indy_timer.c,v 1.4 1997/12/01 17:57:38 ralf Exp $ */ #include <linux/errno.h> @@ -101,10 +101,18 @@ static long last_rtc_update = 0; void indy_timer_interrupt(struct pt_regs *regs) { + unsigned long count; int irq = 7; /* Ack timer and compute new compare. */ - r4k_cur = (read_32bit_cp0_register(CP0_COUNT) + r4k_offset); + count = read_32bit_cp0_register(CP0_COUNT); + if ((count - r4k_cur) >= r4k_offset) { + printk("missed heartbeat: r4k_cur[0x%lx] count[0x%lx]\n", + r4k_cur, count); + r4k_cur = count + r4k_offset; + } + else + r4k_cur += r4k_offset; ack_r4ktimer(r4k_cur); kstat.interrupts[irq]++; do_timer(regs); @@ -123,8 +131,8 @@ void indy_timer_interrupt(struct pt_regs *regs) last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */ } -static inline unsigned long dosample(volatile unsigned char *tcwp, - volatile unsigned char *tc2p) +static unsigned long dosample(volatile unsigned char *tcwp, + volatile unsigned char *tc2p) { unsigned long ct0, ct1; unsigned char msb, lsb; @@ -138,16 +146,12 @@ static inline unsigned long dosample(volatile unsigned char *tcwp, ct0 = read_32bit_cp0_register(CP0_COUNT); /* Latch and spin until top byte of counter2 is zero */ - *tcwp = (SGINT_TCWORD_CNT2 | SGINT_TCWORD_CLAT); - ct1 = read_32bit_cp0_register(CP0_COUNT); - lsb = *tc2p; - msb = *tc2p; - while(msb) { + do { *tcwp = (SGINT_TCWORD_CNT2 | SGINT_TCWORD_CLAT); - ct1 = read_32bit_cp0_register(CP0_COUNT); lsb = *tc2p; msb = *tc2p; - } + ct1 = read_32bit_cp0_register(CP0_COUNT); + } while(msb); /* Stop the counter. */ *tcwp = (SGINT_TCWORD_CNT2 | SGINT_TCWORD_CALL | SGINT_TCWORD_MSWST); @@ -254,11 +258,9 @@ void indy_timer_init(void) tc2p = &p->tcnt2; printk("calculating r4koff... "); - r4k_offset = dosample(tcwp, tc2p); /* First sample. */ - dosample(tcwp, tc2p); /* Eat one... */ - r4k_offset += dosample(tcwp, tc2p); /* Second sample. */ - r4k_offset = (r4k_offset >> 1); /* Get average. */ - r4k_offset = HZ * r4k_offset; /* Multiply by HZ */ + dosample(tcwp, tc2p); /* First sample. */ + dosample(tcwp, tc2p); /* Eat one. */ + r4k_offset = dosample(tcwp, tc2p); /* Second sample. */ printk("%08lx(%d)\n", r4k_offset, (int) r4k_offset); |