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authorWill Deacon2012-07-06 16:46:45 +0200
committerRussell King2012-07-09 18:42:23 +0200
commit923df96b9f31b7d08d8438ff9677326d9537accf (patch)
tree3df937a0431a2ae0500ae011f5742a28611490fa /arch
parentLinux 3.5-rc1 (diff)
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ARM: 7451/1: arch timer: implement read_current_timer and get_cycles
This patch implements read_current_timer using the architected timers when they are selected via CONFIG_ARM_ARCH_TIMER. If they are detected not to be usable at runtime, we return -ENXIO to the caller. Furthermore, if read_current_timer is exported then we can implement get_cycles in terms of it for use as both an entropy source and for implementing __udelay and friends. Tested-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/arch_timer.h3
-rw-r--r--arch/arm/include/asm/timex.h10
-rw-r--r--arch/arm/kernel/arch_timer.c8
3 files changed, 17 insertions, 4 deletions
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index ed2e95d46e29..62e75475e57e 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -1,7 +1,10 @@
#ifndef __ASMARM_ARCH_TIMER_H
#define __ASMARM_ARCH_TIMER_H
+#include <asm/errno.h>
+
#ifdef CONFIG_ARM_ARCH_TIMER
+#define ARCH_HAS_READ_CURRENT_TIMER
int arch_timer_of_register(void);
int arch_timer_sched_clock_init(void);
#else
diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h
index 3be8de3adaba..ce119442277c 100644
--- a/arch/arm/include/asm/timex.h
+++ b/arch/arm/include/asm/timex.h
@@ -12,13 +12,15 @@
#ifndef _ASMARM_TIMEX_H
#define _ASMARM_TIMEX_H
+#include <asm/arch_timer.h>
#include <mach/timex.h>
typedef unsigned long cycles_t;
-static inline cycles_t get_cycles (void)
-{
- return 0;
-}
+#ifdef ARCH_HAS_READ_CURRENT_TIMER
+#define get_cycles() ({ cycles_t c; read_current_timer(&c) ? 0 : c; })
+#else
+#define get_cycles() (0)
+#endif
#endif
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index dd58035621f7..dbbeec4f06e2 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -223,6 +223,14 @@ static cycle_t arch_counter_read(struct clocksource *cs)
return arch_counter_get_cntpct();
}
+int read_current_timer(unsigned long *timer_val)
+{
+ if (!arch_timer_rate)
+ return -ENXIO;
+ *timer_val = arch_counter_get_cntpct();
+ return 0;
+}
+
static struct clocksource clocksource_counter = {
.name = "arch_sys_counter",
.rating = 400,