Re: [PATCH v2 28/31] arm64: Generic timers support

From: Santosh Shilimkar
Date: Fri Aug 17 2012 - 06:21:43 EST


On Tuesday 14 August 2012 11:22 PM, Catalin Marinas wrote:
From: Marc Zyngier<marc.zyngier@xxxxxxx>

This patch adds support for the ARM generic timers with A64 instructions
for accessing the timer registers. It uses the physical counter as the
clock source and the virtual counter as sched_clock.

The timer frequency can be specified via DT or read from the CNTFRQ_EL0
register. The physical counter is also accessible from user space
allowing fast gettimeofday() implementation.

Signed-off-by: Marc Zyngier<marc.zyngier@xxxxxxx>
Signed-off-by: Will Deacon<will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas<catalin.marinas@xxxxxxx>
---

[..]

diff --git a/drivers/clocksource/arm_generic.c b/drivers/clocksource/arm_generic.c
new file mode 100644
index 0000000..05c898c
--- /dev/null
+++ b/drivers/clocksource/arm_generic.c

[..]

+
+static void __cpuinit arch_timer_setup(struct clock_event_device *clk)
+{
+ /* Let's make sure the timer is off before doing anything else */
+ arch_timer_stop();
+
+ clk->features = CLOCK_EVT_FEAT_ONESHOT;
Are these CPU timers wakeup capable or we need the wakeup capable
broadcast timer for low power wakeups ?
In that case C3STOP would be needed here.

Regards
santosh
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