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>
diff --git a/arch/arm/include/asm/timex.h b/arch/arm/include/asm/timex.h
index 3be8de3..ce11944 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