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/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index dd58035..dbbeec4 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -223,6 +223,14 @@
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,