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authorWill Deacon <will.deacon@arm.com>2013-08-23 15:32:29 +0100
committerSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>2013-09-26 09:48:00 +0100
commit037f637767a82907efedda78d3ff405c34020075 (patch)
tree4478cc520fe744be36b559182bd36cbf8f61e705 /include/clocksource
parent46efe547aca8498d51b64460c02366ae4032ca32 (diff)
downloadlinux-stericsson-037f637767a82907efedda78d3ff405c34020075.tar.gz
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 <lorenzo.pieralisi@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Will Deacon <will.deacon@arm.com> [sudeep: moving ARM/ARM64 changes into separate patches and adding Kconfig option] Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Diffstat (limited to 'include/clocksource')
-rw-r--r--include/clocksource/arm_arch_timer.h2
1 files changed, 2 insertions, 0 deletions
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);