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authorWill Deacon <will.deacon@arm.com>2012-07-06 15:47:17 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-07-09 17:42:23 +0100
commitd0a533b18235d36206b9b422efadb7cee444dfdb (patch)
tree43dcdcf9eebd9c88430df031305ca4eb5c2346f4 /arch/arm/kernel/arch_timer.c
parent923df96b9f31b7d08d8438ff9677326d9537accf (diff)
downloadlinux-d0a533b18235d36206b9b422efadb7cee444dfdb.tar.bz2
ARM: 7452/1: delay: allow timer-based delay implementation to be selected
This patch allows a timer-based delay implementation to be selected by switching the delay routines over to use get_cycles, which is implemented in terms of read_current_timer. This further allows us to skip the loop calibration and have a consistent delay function in the face of core frequency scaling. To avoid the pain of dealing with memory-mapped counters, this implementation uses the co-processor interface to the architected timers when they are available. The previous loop-based implementation is kept around for CPUs without the architected timers and we retain both the maximum delay (2ms) and the corresponding conversion factors for determining the number of loops required for a given interval. Since the indirection of the timer routines will only work when called from C, the sa1100 sleep routines are modified to branch to the loop-based delay functions directly. Tested-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/arch_timer.c')
-rw-r--r--arch/arm/kernel/arch_timer.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm/kernel/arch_timer.c b/arch/arm/kernel/arch_timer.c
index dbbeec4f06e2..675cee09c014 100644
--- a/arch/arm/kernel/arch_timer.c
+++ b/arch/arm/kernel/arch_timer.c
@@ -32,6 +32,8 @@ static int arch_timer_ppi2;
static struct clock_event_device __percpu **arch_timer_evt;
+extern void init_current_timer_delay(unsigned long freq);
+
/*
* Architected system timer support.
*/
@@ -304,6 +306,7 @@ static int __init arch_timer_register(void)
if (err)
goto out_free_irq;
+ init_current_timer_delay(arch_timer_rate);
return 0;
out_free_irq: