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ARM: Realview/Versatile: separate out common sched_clock()
Provide a common sched_clock() implementation for Versatile and Realview. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Russell King
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May 2, 2010
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obj-y := clock.o | ||
obj-$(CONFIG_ARM_TIMER_SP804) += timer-sp.o | ||
obj-$(CONFIG_ARCH_REALVIEW) += sched-clock.o | ||
obj-$(CONFIG_ARCH_VERSATILE) += sched-clock.o |
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/* | ||
* linux/arch/arm/plat-versatile/sched-clock.c | ||
* | ||
* Copyright (C) 1999 - 2003 ARM Limited | ||
* Copyright (C) 2000 Deep Blue Solutions Ltd | ||
* | ||
* This program is free software; you can redistribute it and/or modify | ||
* it under the terms of the GNU General Public License as published by | ||
* the Free Software Foundation; either version 2 of the License, or | ||
* (at your option) any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
* GNU General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU General Public License | ||
* along with this program; if not, write to the Free Software | ||
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||
*/ | ||
#include <linux/cnt32_to_63.h> | ||
#include <linux/io.h> | ||
#include <asm/div64.h> | ||
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#include <mach/hardware.h> | ||
#include <mach/platform.h> | ||
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#ifdef VERSATILE_SYS_BASE | ||
#define REFCOUNTER (__io_address(VERSATILE_SYS_BASE) + VERSATILE_SYS_24MHz_OFFSET) | ||
#endif | ||
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#ifdef REALVIEW_SYS_BASE | ||
#define REFCOUNTER (__io_address(REALVIEW_SYS_BASE) + REALVIEW_SYS_24MHz_OFFSET) | ||
#endif | ||
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/* | ||
* This is the Realview and Versatile sched_clock implementation. This | ||
* has a resolution of 41.7ns, and a maximum value of about 35583 days. | ||
* | ||
* The return value is guaranteed to be monotonic in that range as | ||
* long as there is always less than 89 seconds between successive | ||
* calls to this function. | ||
*/ | ||
unsigned long long sched_clock(void) | ||
{ | ||
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 */ | ||
v *= 125<<1; | ||
do_div(v, 3<<1); | ||
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return v; | ||
} |