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ARM: 7444/1: kernel: add arch-timer C3STOP feature 

When a CPU is shutdown its architected timer comparators registers are
lost. Within CPU idle, before processors enter shutdown they enter
clock events broadcast mode through the

clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, cpuid);

function where the local timers are emulated by a global always-on timer.
On CPU resume, the per-CPU tick device normal mode is restored by exiting
broadcast mode through

clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, cpuid);

In order for this mechanism to function, architected timers should add to
their feature C3STOP, which means that they are not able to function when the
CPU is in off-mode.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Lorenzo Pieralisi 2012-07-06 11:06:49 +01:00 committed by Russell King
parent a5203c4ce6
commit 27a5569dc6
1 changed files with 1 additions and 1 deletions
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2
arch/arm/kernel/arch_timer.c
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@ -137,7 +137,7 @@ static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
/* Be safe... */
arch_timer_disable();
clk->features = CLOCK_EVT_FEAT_ONESHOT;
clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
clk->name = "arch_sys_timer";
clk->rating = 450;
clk->set_mode = arch_timer_set_mode;