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authorWill Deacon <will.deacon@arm.com>2013-08-23 18:32:29 +0400
committerSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>2013-09-26 12:48:00 +0400
commit037f637767a82907efedda78d3ff405c34020075 (patch)
tree4478cc520fe744be36b559182bd36cbf8f61e705 /drivers/clocksource/Kconfig
parent46efe547aca8498d51b64460c02366ae4032ca32 (diff)
downloadlinux-037f637767a82907efedda78d3ff405c34020075.tar.xz
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 'drivers/clocksource/Kconfig')
-rw-r--r--drivers/clocksource/Kconfig15
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 41c69469ce20..559d80335446 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -74,6 +74,21 @@ config ARM_ARCH_TIMER
bool
select CLKSRC_OF if OF
+config ARM_ARCH_TIMER_EVTSTREAM
+ bool "Support for ARM architected timer event stream generation"
+ default y if ARM_ARCH_TIMER
+ help
+ This option enables support for event stream generation based on
+ the ARM architected timer. It is used for waking up CPUs executing
+ the wfe instruction at a frequency represented as a power-of-2
+ divisor of the clock rate.
+ The main use of the event stream is wfe-based timeouts of userspace
+ locking implementations. It might also be useful for imposing timeout
+ on wfe to safeguard against any programming errors in case an expected
+ event is not generated.
+ This must be disabled for hardware validation purposes to detect any
+ hardware anomalies of missing events.
+
config ARM_GLOBAL_TIMER
bool
select CLKSRC_OF if OF