54 lines
1.7 KiB
C
54 lines
1.7 KiB
C
/*
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* linux/arch/arm/plat-versatile/sched-clock.c
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*
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* Copyright (C) 1999 - 2003 ARM Limited
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* Copyright (C) 2000 Deep Blue Solutions Ltd
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/cnt32_to_63.h>
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#include <linux/io.h>
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#include <asm/div64.h>
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#include <mach/hardware.h>
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#include <mach/platform.h>
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#ifdef VERSATILE_SYS_BASE
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#define REFCOUNTER (__io_address(VERSATILE_SYS_BASE) + VERSATILE_SYS_24MHz_OFFSET)
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#endif
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#ifdef REALVIEW_SYS_BASE
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#define REFCOUNTER (__io_address(REALVIEW_SYS_BASE) + REALVIEW_SYS_24MHz_OFFSET)
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#endif
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/*
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* This is the Realview and Versatile sched_clock implementation. This
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* has a resolution of 41.7ns, and a maximum value of about 35583 days.
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*
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* The return value is guaranteed to be monotonic in that range as
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* long as there is always less than 89 seconds between successive
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* calls to this function.
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*/
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unsigned long long sched_clock(void)
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{
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unsigned long long v = cnt32_to_63(readl(REFCOUNTER));
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/* the <<1 gets rid of the cnt_32_to_63 top bit saving on a bic insn */
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v *= 125<<1;
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do_div(v, 3<<1);
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return v;
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}
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