| From 659368dde84e22aa3ff10187e05ce202fde8d804 Mon Sep 17 00:00:00 2001 |
| From: Wu Zhangjin <wuzhangjin@gmail.com> |
| Date: Mon, 1 Feb 2010 18:47:38 +0800 |
| Subject: [PATCH] MIPS: add a common mips_sched_clock() |
| |
| commit 659368dde84e22aa3ff10187e05ce202fde8d804 in tip. |
| |
| Because the high resolution sched_clock() for r4k has the same overflow |
| problem and solution mentioned in "MIPS: Octeon: Use non-overflowing |
| arithmetic in sched_clock". |
| |
| "With typical mult and shift values, the calculation for Octeon's |
| sched_clock overflows when using 64-bit arithmetic. Use 128-bit |
| calculations instead." |
| |
| To reduce the duplication, This patch abstracts the solution into an |
| inline funciton mips_sched_clock() into arch/mips/include/asm/time.h |
| from arch/mips/cavium-octeon/csrc-octeon.c. |
| |
| Two patches for Cavium and R4K will be sent out respectively to use this |
| common function. |
| |
| Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com> |
| |
| diff --git a/arch/mips/include/asm/time.h b/arch/mips/include/asm/time.h |
| index c7f1bfe..f7bd5ce 100644 |
| --- a/arch/mips/include/asm/time.h |
| +++ b/arch/mips/include/asm/time.h |
| @@ -96,4 +96,34 @@ static inline void clockevent_set_clock(struct clock_event_device *cd, |
| clockevents_calc_mult_shift(cd, clock, 4); |
| } |
| |
| +static inline unsigned long long mips_sched_clock(struct clocksource *cs, u64 cnt) |
| +{ |
| + /* 64-bit arithmatic can overflow, so use 128-bit. */ |
| +#if (__GNUC__ < 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ <= 3)) |
| + u64 t1, t2, t3; |
| + unsigned long long rv; |
| + u64 mult = cs->mult; |
| + u64 shift = cs->shift; |
| + |
| + asm ( |
| + "dmultu\t%[cnt],%[mult]\n\t" |
| + "nor\t%[t1],$0,%[shift]\n\t" |
| + "mfhi\t%[t2]\n\t" |
| + "mflo\t%[t3]\n\t" |
| + "dsll\t%[t2],%[t2],1\n\t" |
| + "dsrlv\t%[rv],%[t3],%[shift]\n\t" |
| + "dsllv\t%[t1],%[t2],%[t1]\n\t" |
| + "or\t%[rv],%[t1],%[rv]\n\t" |
| + : [rv] "=&r" (rv), [t1] "=&r" (t1), [t2] "=&r" (t2), [t3] "=&r" (t3) |
| + : [cnt] "r" (cnt), [mult] "r" (mult), [shift] "r" (shift) |
| + : "hi", "lo"); |
| + return rv; |
| +#else /* GCC > 4.3 do it the easy way. */ |
| + unsigned int __attribute__((mode(TI))) t = cnt; |
| + |
| + t = (t * cs->mult) >> cs->shift; |
| + return (unsigned long long)t; |
| +#endif |
| +} |
| + |
| #endif /* _ASM_TIME_H */ |
| -- |
| 1.7.1.1 |
| |