From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- include/asm-mips/timex.h | 54 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 include/asm-mips/timex.h (limited to 'include/asm-mips/timex.h') diff --git a/include/asm-mips/timex.h b/include/asm-mips/timex.h new file mode 100644 index 000000000000..98aa737b34aa --- /dev/null +++ b/include/asm-mips/timex.h @@ -0,0 +1,54 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 1998, 1999, 2003 by Ralf Baechle + */ +#ifndef _ASM_TIMEX_H +#define _ASM_TIMEX_H + +#include + +/* + * This is the frequency of the timer used for Linux's timer interrupt. + * The value should be defined as accurate as possible or under certain + * circumstances Linux timekeeping might become inaccurate or fail. + * + * For many system the exact clockrate of the timer isn't known but due to + * the way this value is used we can get away with a wrong value as long + * as this value is: + * + * - a multiple of HZ + * - a divisor of the actual rate + * + * 500000 is a good such cheat value. + * + * The obscure number 1193182 is the same as used by the original i8254 + * time in legacy PC hardware; the chip unfortunately also found in a + * bunch of MIPS systems. The last remaining user of the i8254 for the + * timer interrupt is the RM200; it's a very standard system so there is + * no reason to make this a separate architecture. + */ + +#include + +/* + * Standard way to access the cycle counter. + * Currently only used on SMP for scheduling. + * + * Only the low 32 bits are available as a continuously counting entity. + * But this only means we'll force a reschedule every 8 seconds or so, + * which isn't an evil thing. + * + * We know that all SMP capable CPUs have cycle counters. + */ + +typedef unsigned int cycles_t; + +static inline cycles_t get_cycles (void) +{ + return read_c0_count(); +} + +#endif /* _ASM_TIMEX_H */ -- cgit v1.2.2