From 037f637767a82907efedda78d3ff405c34020075 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 23 Aug 2013 15:32:29 +0100 Subject: drivers: clocksource: add support for ARM architected timer event stream The ARM architected timer can generate events (used for waking up CPUs executing the wfe instruction) at a frequency represented as a power-of-2 divisor of the clock rate. An event stream might be used: - To implement wfe-based timeouts for userspace locking implementations. - To impose a timeout on a wfe for safeguarding against any programming error in case an expected event is not generated. This patch computes the event stream frequency aiming for a period of 100us between events. It uses ARM/ARM64 specific backends to configure and enable the event stream. Cc: Lorenzo Pieralisi Reviewed-by: Catalin Marinas Acked-by: Olof Johansson Signed-off-by: Will Deacon [sudeep: moving ARM/ARM64 changes into separate patches and adding Kconfig option] Signed-off-by: Sudeep KarkadaNagesha --- include/clocksource/arm_arch_timer.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/clocksource') diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h index 8707dae4cee2..6d26b40cbf5d 100644 --- a/include/clocksource/arm_arch_timer.h +++ b/include/clocksource/arm_arch_timer.h @@ -41,6 +41,8 @@ enum arch_timer_reg { #define ARCH_TIMER_USR_VT_ACCESS_EN (1 << 8) /* virtual timer registers */ #define ARCH_TIMER_USR_PT_ACCESS_EN (1 << 9) /* physical timer registers */ +#define ARCH_TIMER_EVT_STREAM_FREQ 10000 /* 100us */ + #ifdef CONFIG_ARM_ARCH_TIMER extern u32 arch_timer_get_rate(void); -- cgit v1.2.3