diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-mips/timex.h |
Linux-2.6.12-rc2v2.6.12-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!
Diffstat (limited to 'include/asm-mips/timex.h')
-rw-r--r-- | include/asm-mips/timex.h | 54 |
1 files changed, 54 insertions, 0 deletions
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 @@ | |||
1 | /* | ||
2 | * This file is subject to the terms and conditions of the GNU General Public | ||
3 | * License. See the file "COPYING" in the main directory of this archive | ||
4 | * for more details. | ||
5 | * | ||
6 | * Copyright (C) 1998, 1999, 2003 by Ralf Baechle | ||
7 | */ | ||
8 | #ifndef _ASM_TIMEX_H | ||
9 | #define _ASM_TIMEX_H | ||
10 | |||
11 | #include <asm/mipsregs.h> | ||
12 | |||
13 | /* | ||
14 | * This is the frequency of the timer used for Linux's timer interrupt. | ||
15 | * The value should be defined as accurate as possible or under certain | ||
16 | * circumstances Linux timekeeping might become inaccurate or fail. | ||
17 | * | ||
18 | * For many system the exact clockrate of the timer isn't known but due to | ||
19 | * the way this value is used we can get away with a wrong value as long | ||
20 | * as this value is: | ||
21 | * | ||
22 | * - a multiple of HZ | ||
23 | * - a divisor of the actual rate | ||
24 | * | ||
25 | * 500000 is a good such cheat value. | ||
26 | * | ||
27 | * The obscure number 1193182 is the same as used by the original i8254 | ||
28 | * time in legacy PC hardware; the chip unfortunately also found in a | ||
29 | * bunch of MIPS systems. The last remaining user of the i8254 for the | ||
30 | * timer interrupt is the RM200; it's a very standard system so there is | ||
31 | * no reason to make this a separate architecture. | ||
32 | */ | ||
33 | |||
34 | #include <timex.h> | ||
35 | |||
36 | /* | ||
37 | * Standard way to access the cycle counter. | ||
38 | * Currently only used on SMP for scheduling. | ||
39 | * | ||
40 | * Only the low 32 bits are available as a continuously counting entity. | ||
41 | * But this only means we'll force a reschedule every 8 seconds or so, | ||
42 | * which isn't an evil thing. | ||
43 | * | ||
44 | * We know that all SMP capable CPUs have cycle counters. | ||
45 | */ | ||
46 | |||
47 | typedef unsigned int cycles_t; | ||
48 | |||
49 | static inline cycles_t get_cycles (void) | ||
50 | { | ||
51 | return read_c0_count(); | ||
52 | } | ||
53 | |||
54 | #endif /* _ASM_TIMEX_H */ | ||