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ARM: sched_clock: allow changing to higher frequency counter 

Allow multiple calls to setup_sched_clock and switch to the new counter
if it is higher frequency.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
This commit is contained in:
Rob Herring 2013-02-08 16:14:59 -06:00
parent 3d5a965823
commit c115739da8
1 changed files with 5 additions and 1 deletions
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6
arch/arm/kernel/sched_clock.c
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@ -20,6 +20,7 @@ struct clock_data {
u64 epoch_ns;
u32 epoch_cyc;
u32 epoch_cyc_copy;
unsigned long rate;
u32 mult;
u32 shift;
bool suspended;
@ -113,11 +114,14 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
u64 res, wrap;
char r_unit;
if (cd.rate > rate)
return;
BUG_ON(bits > 32);
WARN_ON(!irqs_disabled());
WARN_ON(read_sched_clock != jiffy_sched_clock_read);
read_sched_clock = read;
sched_clock_mask = (1 << bits) - 1;
cd.rate = rate;
/* calculate the mult/shift to convert counter ticks to ns. */
clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0);