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>

1 files changed, 53 insertions, 0 deletions

diff --git a/arch/arm/plat-versatile/sched-clock.c b/arch/arm/plat-versatile/sched-clock.c
new file mode 100644
index 00000000000..9768cf7e83d
--- /dev/null
+++ b/arch/arm/plat-versatile/sched-clock.c
@@ -0,0 +1,53 @@
+/*
+ *  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>
+
+#include <mach/hardware.h>
+#include <mach/platform.h>
+
+#ifdef VERSATILE_SYS_BASE
+#define REFCOUNTER	(__io_address(VERSATILE_SYS_BASE) + VERSATILE_SYS_24MHz_OFFSET)
+#endif
+
+#ifdef REALVIEW_SYS_BASE
+#define REFCOUNTER	(__io_address(REALVIEW_SYS_BASE) + REALVIEW_SYS_24MHz_OFFSET)
+#endif
+
+/*
+ * 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));
+
+	/* 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);
+
+	return v;
+}