[PATCH 32/40] ARM: sa1100: convert sched_clock() to use new infrastructure

[Russell King - ARM Linux]

Convert sa1100 to use the new sched_clock() infrastructure for extending
32bit counters to full 64-bit nanoseconds.

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
---
 arch/arm/Kconfig               |    1 +
 arch/arm/mach-sa1100/generic.c |   23 -----------------------
 arch/arm/mach-sa1100/time.c    |   30 ++++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 23 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 23035d6..0e1a966 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -642,6 +642,7 @@ config ARCH_SA1100
 	select CPU_FREQ
 	select GENERIC_CLOCKEVENTS
 	select HAVE_CLK
+	select HAVE_SCHED_CLOCK
 	select TICK_ONESHOT
 	select ARCH_REQUIRE_GPIOLIB
 	help
diff --git a/arch/arm/mach-sa1100/generic.c b/arch/arm/mach-sa1100/generic.c
index 33b4969..fbc224d 100644
--- a/arch/arm/mach-sa1100/generic.c
+++ b/arch/arm/mach-sa1100/generic.c
@@ -16,9 +16,7 @@
 #include <linux/pm.h>
 #include <linux/cpufreq.h>
 #include <linux/ioport.h>
-#include <linux/sched.h>	/* just for sched_clock() - funny that */
 #include <linux/platform_device.h>
-#include <linux/cnt32_to_63.h>
 
 #include <asm/div64.h>
 #include <mach/hardware.h>
@@ -110,27 +108,6 @@ unsigned int sa11x0_getspeed(unsigned int cpu)
 }
 
 /*
- * This is the SA11x0 sched_clock implementation.  This has
- * a resolution of 271ns, and a maximum value of 32025597s (370 days).
- *
- * The return value is guaranteed to be monotonic in that range as
- * long as there is always less than 582 seconds between successive
- * calls to this function.
- *
- *  ( * 1E9 / 3686400 => * 78125 / 288)
- */
-unsigned long long notrace sched_clock(void)
-{
-	unsigned long long v = cnt32_to_63(OSCR);
-
-	/* the <<1 gets rid of the cnt_32_to_63 top bit saving on a bic insn */
-	v *= 78125<<1;
-	do_div(v, 288<<1);
-
-	return v;
-}
-
-/*
  * Default power-off for SA1100
  */
 static void sa1100_power_off(void)
diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c
index 96154f5..ae4f3d8 100644
--- a/arch/arm/mach-sa1100/time.c
+++ b/arch/arm/mach-sa1100/time.c
@@ -12,12 +12,39 @@
 #include <linux/errno.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/sched.h>	/* just for sched_clock() - funny that */
 #include <linux/timex.h>
 #include <linux/clockchips.h>
 
 #include <asm/mach/time.h>
+#include <asm/sched_clock.h>
 #include <mach/hardware.h>
 
+/*
+ * This is the SA11x0 sched_clock implementation.
+ */
+static DEFINE_CLOCK_DATA(cd);
+
+/*
+ * Constants generated by clocks_calc_mult_shift(m, s, 3.6864MHz,
+ * NSEC_PER_SEC, 60).
+ * This gives a resolution of about 271ns and a wrap period of about 19min.
+ */
+#define SC_MULT		2275555556u
+#define SC_SHIFT	23
+
+unsigned long long notrace sched_clock(void)
+{
+	u32 cyc = OSCR;
+	return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT);
+}
+
+static void notrace sa1100_update_sched_clock(void)
+{
+	u32 cyc = OSCR;
+	update_sched_clock(&cd, cyc, (u32)~0);
+}
+
 #define MIN_OSCR_DELTA 2
 
 static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
@@ -96,6 +123,9 @@ static void __init sa1100_timer_init(void)
 	OIER = 0;		/* disable any timer interrupts */
 	OSSR = 0xf;		/* clear status on all timers */
 
+	init_fixed_sched_clock(&cd, sa1100_update_sched_clock, 32,
+			       3686400, SC_MULT, SC_SHIFT);
+
 	ckevt_sa1100_osmr0.mult =
 		div_sc(3686400, NSEC_PER_SEC, ckevt_sa1100_osmr0.shift);
 	ckevt_sa1100_osmr0.max_delta_ns =
-- 
1.6.2.5