Blackfin: unify sched_clock() handling between clock sources

Currently sched_clock() is only defined when using CYCLES as a clock
source.  Declare sched_clock() in common code and mark it with notrace to
prevent invoking sched_clock() recursively (because ftrace uses
sched_clock() to record time).
Signed-off-by: NYi Li <yi.li@analog.com>
Signed-off-by: NMike Frysinger <vapier@gentoo.org>

arch/blackfin/kernel/time-ts.c

@@ -22,8 +22,6 @@
 #include <asm/time.h>
 #include <asm/gptimers.h>
 
-#if defined(CONFIG_CYCLES_CLOCKSOURCE)
-
 /* Accelerators for sched_clock()
  * convert from cycles(64bits) => nanoseconds (64bits)
  *  basic equation:
@@ -46,20 +44,23 @@
  *			-johnstul@us.ibm.com "math is hard, lets go shopping!"
  */
 
-static unsigned long cyc2ns_scale;
 #define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
 
-static inline void set_cyc2ns_scale(unsigned long cpu_khz)
+static inline unsigned long cyc2ns_scale(unsigned long cpu_khz)
 {
-	cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
+	return (1000000 << CYC2NS_SCALE_FACTOR) / cpu_khz;
 }
 
-static inline unsigned long long cycles_2_ns(cycle_t cyc)
+static inline unsigned long long cycles_2_ns(cycle_t cyc, unsigned long cyc2ns_scale)
 {
 	return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
 }
 
-static cycle_t bfin_read_cycles(struct clocksource *cs)
+#if defined(CONFIG_CYCLES_CLOCKSOURCE)
+
+static unsigned long cycles_cyc2ns_scale;
+
+static notrace cycle_t bfin_read_cycles(struct clocksource *cs)
 {
 	return __bfin_cycles_off + (get_cycles() << __bfin_cycles_mod);
 }
@@ -73,14 +74,14 @@ static struct clocksource bfin_cs_cycles = {
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
-unsigned long long sched_clock(void)
+static inline unsigned long long bfin_cs_cycles_sched_clock(void)
 {
-	return cycles_2_ns(bfin_read_cycles(&bfin_cs_cycles));
+	return cycles_2_ns(bfin_read_cycles(&bfin_cs_cycles), cycles_cyc2ns_scale);
 }
 
 static int __init bfin_cs_cycles_init(void)
 {
-	set_cyc2ns_scale(get_cclk() / 1000);
+	cycles_cyc2ns_scale = cyc2ns_scale(get_cclk() / 1000);
 
 	bfin_cs_cycles.mult = \
 		clocksource_hz2mult(get_cclk(), bfin_cs_cycles.shift);
@@ -96,6 +97,8 @@ static int __init bfin_cs_cycles_init(void)
 
 #ifdef CONFIG_GPTMR0_CLOCKSOURCE
 
+unsigned long gptimer0_cyc2ns_scale;
+
 void __init setup_gptimer0(void)
 {
 	disable_gptimers(TIMER0bit);
@@ -122,8 +125,15 @@ static struct clocksource bfin_cs_gptimer0 = {
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };
 
+static inline unsigned long long bfin_cs_gptimer0_sched_clock(void)
+{
+	return cycles_2_ns(bfin_read_TIMER0_COUNTER(), gptimer0_cyc2ns_scale);
+}
+
 static int __init bfin_cs_gptimer0_init(void)
 {
+	gptimer0_cyc2ns_scale = cyc2ns_scale(get_sclk() / 1000);
+
 	setup_gptimer0();
 
 	bfin_cs_gptimer0.mult = \
@@ -138,6 +148,19 @@ static int __init bfin_cs_gptimer0_init(void)
 # define bfin_cs_gptimer0_init()
 #endif
 
+
+#if defined(CONFIG_GPTMR0_CLOCKSOURCE) || defined(CONFIG_CYCLES_CLOCKSOURCE)
+/* prefer to use cycles since it has higher rating */
+notrace unsigned long long sched_clock(void)
+{
+#if defined(CONFIG_CYCLES_CLOCKSOURCE)
+	return bfin_cs_cycles_sched_clock();
+#else
+	return bfin_cs_gptimer0_sched_clock();
+#endif
+}
+#endif
+
 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 __attribute__((l1_text))
 #endif