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-rw-r--r--arch/arm/kernel/arch_timer.c29
-rw-r--r--arch/arm/kernel/sched_clock.c15
-rw-r--r--arch/arm/kernel/time.c7
3 files changed, 32 insertions, 19 deletions
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index d957a51435d..59dcdced6e3 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -22,9 +22,11 @@ static unsigned long arch_timer_read_counter_long(void)
return arch_timer_read_counter();
}
-static u32 arch_timer_read_counter_u32(void)
+static u32 sched_clock_mult __read_mostly;
+
+static unsigned long long notrace arch_timer_sched_clock(void)
{
- return arch_timer_read_counter();
+ return arch_timer_read_counter() * sched_clock_mult;
}
static struct delay_timer arch_delay_timer;
@@ -37,25 +39,20 @@ static void __init arch_timer_delay_timer_register(void)
register_current_timer_delay(&arch_delay_timer);
}
-int __init arch_timer_of_register(void)
+int __init arch_timer_arch_init(void)
{
- int ret;
+ u32 arch_timer_rate = arch_timer_get_rate();
- ret = arch_timer_init();
- if (ret)
- return ret;
+ if (arch_timer_rate == 0)
+ return -ENXIO;
arch_timer_delay_timer_register();
- return 0;
-}
-
-int __init arch_timer_sched_clock_init(void)
-{
- if (arch_timer_get_rate() == 0)
- return -ENXIO;
+ /* Cache the sched_clock multiplier to save a divide in the hot path. */
+ sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
+ sched_clock_func = arch_timer_sched_clock;
+ pr_info("sched_clock: ARM arch timer >56 bits at %ukHz, resolution %uns\n",
+ arch_timer_rate / 1000, sched_clock_mult);
- setup_sched_clock(arch_timer_read_counter_u32,
- 32, arch_timer_get_rate());
return 0;
}
diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index 59d2adb764a..e8edcaa0e43 100644
--- a/arch/arm/kernel/sched_clock.c
+++ b/arch/arm/kernel/sched_clock.c
@@ -20,6 +20,7 @@ struct clock_data {
u64 epoch_ns;
u32 epoch_cyc;
u32 epoch_cyc_copy;
+ unsigned long rate;
u32 mult;
u32 shift;
bool suspended;
@@ -113,11 +114,14 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
u64 res, wrap;
char r_unit;
+ if (cd.rate > rate)
+ return;
+
BUG_ON(bits > 32);
WARN_ON(!irqs_disabled());
- WARN_ON(read_sched_clock != jiffy_sched_clock_read);
read_sched_clock = read;
sched_clock_mask = (1 << bits) - 1;
+ cd.rate = rate;
/* calculate the mult/shift to convert counter ticks to ns. */
clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0);
@@ -161,12 +165,19 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
pr_debug("Registered %pF as sched_clock source\n", read);
}
-unsigned long long notrace sched_clock(void)
+static unsigned long long notrace sched_clock_32(void)
{
u32 cyc = read_sched_clock();
return cyc_to_sched_clock(cyc, sched_clock_mask);
}
+unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32;
+
+unsigned long long notrace sched_clock(void)
+{
+ return sched_clock_func();
+}
+
void __init sched_clock_postinit(void)
{
/*
diff --git a/arch/arm/kernel/time.c b/arch/arm/kernel/time.c
index 955d92d265e..abff4e9aaee 100644
--- a/arch/arm/kernel/time.c
+++ b/arch/arm/kernel/time.c
@@ -22,6 +22,7 @@
#include <linux/errno.h>
#include <linux/profile.h>
#include <linux/timer.h>
+#include <linux/clocksource.h>
#include <linux/irq.h>
#include <asm/thread_info.h>
@@ -115,6 +116,10 @@ int __init register_persistent_clock(clock_access_fn read_boot,
void __init time_init(void)
{
- machine_desc->init_time();
+ if (machine_desc->init_time)
+ machine_desc->init_time();
+ else
+ clocksource_of_init();
+
sched_clock_postinit();
}