[RFC PATCH 0/5] clockevents: decouple broadcast mechanism from drivers

From: Mark Rutland
Date: Tue Dec 18 2012 - 07:07:02 EST

In some SMP systems, cpu-local timers may stop delivering interrupts
when in low power states, or not all CPUs may have local timers. To
support these systems we have a mechanism for broadcasting timer ticks
to other CPUs. This mechanism relies on the struct
clock_event_device::broadcast function pointer, which is a
driver-specific mechanism for broadcasting ticks to other CPUs.

As the broadcast mechanism is architecture-specific, placing the
broadcast function on struct clock_event_device ties each driver to a
single architecture. Additionally the driver or architecture backend
must handle the routing of broadcast ticks to the correct
clock_event_device, leading to duplication of the list of active

These patches introduce a generic mechanism for handling the receipt of
timer broadcasts, and an optional architecture-specific broadcast
function which allows drivers to be decoupled from a particular
architecture will retaining support for timer tick broadcasts. These
mechanisms are wired up for the arm port, and have been boot-tested on a


Mark Rutland (5):
ARM: remove useless guard in smp.c
clockevents: Add generic timer broadcast receiver
ARM: Use generic timer broadcast receive
clockevents: Add generic timer broadcast function
ARM: Add generic timer broadcast support

arch/arm/Kconfig | 1 +
arch/arm/kernel/smp.c | 15 ++-------------
include/linux/clockchips.h | 9 +++++++++
kernel/time/Kconfig | 4 ++++
kernel/time/tick-broadcast.c | 30 ++++++++++++++++++++++++++++++
5 files changed, 46 insertions(+), 13 deletions(-)

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