diff options
Diffstat (limited to 'arch/arm/mach-pxa/time.c')
| -rw-r--r-- | arch/arm/mach-pxa/time.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c index 98d27e6..7916311 100644 --- a/arch/arm/mach-pxa/time.c +++ b/arch/arm/mach-pxa/time.c @@ -16,11 +16,48 @@ #include <linux/init.h> #include <linux/interrupt.h> #include <linux/clockchips.h> +#include <linux/sched.h> +#include <asm/div64.h> +#include <asm/cnt32_to_63.h> #include <asm/mach/irq.h> #include <asm/mach/time.h> #include <asm/arch/pxa-regs.h> +/* + * This is PXA's sched_clock implementation. This has a resolution + * of at least 308 ns and a maximum value of 208 days. + * + * The return value is guaranteed to be monotonic in that range as + * long as there is always less than 582 seconds between successive + * calls to sched_clock() which should always be the case in practice. + */ + +#define OSCR2NS_SCALE_FACTOR 10 + +static unsigned long oscr2ns_scale; + +static void __init set_oscr2ns_scale(unsigned long oscr_rate) +{ + unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR; + do_div(v, oscr_rate); + oscr2ns_scale = v; + /* + * We want an even value to automatically clear the top bit + * returned by cnt32_to_63() without an additional run time + * instruction. So if the LSB is 1 then round it up. + */ + if (oscr2ns_scale & 1) + oscr2ns_scale++; +} + +unsigned long long sched_clock(void) +{ + unsigned long long v = cnt32_to_63(OSCR); + return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR; +} + + static irqreturn_t pxa_ost0_interrupt(int irq, void *dev_id) { @@ -152,6 +189,8 @@ static void __init pxa_timer_init(void) OIER = 0; OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3; + set_oscr2ns_scale(CLOCK_TICK_RATE); + ckevt_pxa_osmr0.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC, ckevt_pxa_osmr0.shift); ckevt_pxa_osmr0.max_delta_ns = |
