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-rw-r--r--arch/arm/mach-versatile/core.c14
1 files changed, 10 insertions, 4 deletions
diff --git a/arch/arm/mach-versatile/core.c b/arch/arm/mach-versatile/core.c
index 3b8576111c16..998b398df30e 100644
--- a/arch/arm/mach-versatile/core.c
+++ b/arch/arm/mach-versatile/core.c
@@ -27,6 +27,7 @@
27#include <linux/amba/bus.h> 27#include <linux/amba/bus.h>
28#include <linux/amba/clcd.h> 28#include <linux/amba/clcd.h>
29 29
30#include <asm/cnt32_to_63.h>
30#include <asm/system.h> 31#include <asm/system.h>
31#include <asm/hardware.h> 32#include <asm/hardware.h>
32#include <asm/io.h> 33#include <asm/io.h>
@@ -228,14 +229,19 @@ void __init versatile_map_io(void)
228 229
229/* 230/*
230 * This is the Versatile sched_clock implementation. This has 231 * This is the Versatile sched_clock implementation. This has
231 * a resolution of 41.7ns, and a maximum value of about 179s. 232 * a resolution of 41.7ns, and a maximum value of about 35583 days.
233 *
234 * The return value is guaranteed to be monotonic in that range as
235 * long as there is always less than 89 seconds between successive
236 * calls to this function.
232 */ 237 */
233unsigned long long sched_clock(void) 238unsigned long long sched_clock(void)
234{ 239{
235 unsigned long long v; 240 unsigned long long v = cnt32_to_63(readl(VERSATILE_REFCOUNTER));
236 241
237 v = (unsigned long long)readl(VERSATILE_REFCOUNTER) * 125; 242 /* the <<1 gets rid of the cnt_32_to_63 top bit saving on a bic insn */
238 do_div(v, 3); 243 v *= 125<<1;
244 do_div(v, 3<<1);
239 245
240 return v; 246 return v;
241} 247}