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+/*
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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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+
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+#include <mach/hardware.h>
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+#include <mach/platform.h>
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+
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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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+
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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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+/*
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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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+
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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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+
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+ return v;
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+}
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