diff options
| author | Will Deacon | 2013-08-23 16:32:29 +0200 |
|---|---|---|
| committer | Sudeep KarkadaNagesha | 2013-09-26 10:48:00 +0200 |
| commit | 037f637767a82907efedda78d3ff405c34020075 (patch) | |
| tree | 4478cc520fe744be36b559182bd36cbf8f61e705 /drivers/clocksource/Kconfig | |
| parent | ARM64: arch_timer: add support to configure and enable event stream (diff) | |
| download | kernel-qcow2-linux-037f637767a82907efedda78d3ff405c34020075.tar.gz kernel-qcow2-linux-037f637767a82907efedda78d3ff405c34020075.tar.xz kernel-qcow2-linux-037f637767a82907efedda78d3ff405c34020075.zip | |
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/Kconfig | 15 |
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 |