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1 | /* |
2 | * linux/arch/arm/plat-versatile/sched-clock.c |
3 | * |
4 | * Copyright (C) 1999 - 2003 ARM Limited |
5 | * Copyright (C) 2000 Deep Blue Solutions Ltd |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License as published by |
9 | * the Free Software Foundation; either version 2 of the License, or |
10 | * (at your option) any later version. |
11 | * |
12 | * This program is distributed in the hope that it will be useful, |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | * GNU General Public License for more details. |
16 | * |
17 | * You should have received a copy of the GNU General Public License |
18 | * along with this program; if not, write to the Free Software |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
20 | */ |
21 | #include <linux/cnt32_to_63.h> |
22 | #include <linux/io.h> |
23 | #include <asm/div64.h> |
24 | |
25 | #include <mach/hardware.h> |
26 | #include <mach/platform.h> |
27 | |
28 | #ifdef VERSATILE_SYS_BASE |
29 | #define REFCOUNTER (__io_address(VERSATILE_SYS_BASE) + VERSATILE_SYS_24MHz_OFFSET) |
30 | #endif |
31 | |
32 | #ifdef REALVIEW_SYS_BASE |
33 | #define REFCOUNTER (__io_address(REALVIEW_SYS_BASE) + REALVIEW_SYS_24MHz_OFFSET) |
34 | #endif |
35 | |
36 | /* |
37 | * This is the Realview and Versatile sched_clock implementation. This |
38 | * has a resolution of 41.7ns, and a maximum value of about 35583 days. |
39 | * |
40 | * The return value is guaranteed to be monotonic in that range as |
41 | * long as there is always less than 89 seconds between successive |
42 | * calls to this function. |
43 | */ |
44 | unsigned long long sched_clock(void) |
45 | { |
46 | unsigned long long v = cnt32_to_63(readl(REFCOUNTER)); |
47 | |
48 | /* the <<1 gets rid of the cnt_32_to_63 top bit saving on a bic insn */ |
49 | v *= 125<<1; |
50 | do_div(v, 3<<1); |
51 | |
52 | return v; |
53 | } |
54 |
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od-2011-09-18
v2.6.34-rc5
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v3.9