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ARM: versatile: convert sched_clock() to use new infrastructure

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Convert versatile platforms to use the new sched_clock() infrastructure
for extending 32bit counters to full 64-bit nanoseconds.

Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King
2010-12-15 21:56:47 +00:00
parent f06a162462
commit 1da0c89c66
5 changed files with 56 additions and 24 deletions
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6
arch/arm/plat-versatile/include/plat/sched_clock.h Normal file
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@@ -0,0 +1,6 @@
#ifndef ARM_PLAT_SCHED_CLOCK_H
#define ARM_PLAT_SCHED_CLOCK_H
void versatile_sched_clock_init(void __iomem *, unsigned long);
#endif

52
arch/arm/plat-versatile/sched-clock.c
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@@ -18,37 +18,41 @@
* 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 <linux/sched.h>
#include <asm/div64.h>
#include <mach/hardware.h>
#include <mach/platform.h>
#include <asm/sched_clock.h>
#include <plat/sched_clock.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
static DEFINE_CLOCK_DATA(cd);
static void __iomem *ctr;
/*
* 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.
* Constants generated by clocks_calc_mult_shift(m, s, 24MHz, NSEC_PER_SEC, 60).
* This gives a resolution of about 41ns and a wrap period of about 178s.
*/
#define SC_MULT 2796202667u
#define SC_SHIFT 26
unsigned long long notrace 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;
if (ctr) {
u32 cyc = readl(ctr);
return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0,
SC_MULT, SC_SHIFT);
} else
return 0;
}
static void notrace versatile_update_sched_clock(void)
{
u32 cyc = readl(ctr);
update_sched_clock(&cd, cyc, (u32)~0);
}
void __init versatile_sched_clock_init(void __iomem *reg, unsigned long rate)
{
ctr = reg;
init_fixed_sched_clock(&cd, versatile_update_sched_clock,
32, rate, SC_MULT, SC_SHIFT);
}