From 8a3269fc21cc4405d80b362139c078cf655a505a Mon Sep 17 00:00:00 2001 From: Stefan Agner Date: Tue, 12 May 2009 10:30:41 -0700 Subject: [ARM] orion: sched_clock implementation for orion platforms sched_clock implementation for orion platform. Its realized using free-running clocksource timer, which provides a resolution of 7.5ns (depending on tclk). It's derived from PXA's sched_clock implementation. [ nico: renamed orion2ns to tclk2ns, fixed max value in the comment ] Signed-off-by: Stefan Agner Signed-off-by: Nicolas Pitre --- arch/arm/plat-orion/time.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) (limited to 'arch/arm/plat-orion/time.c') diff --git a/arch/arm/plat-orion/time.c b/arch/arm/plat-orion/time.c index de8a001fc3a9..b856cec81702 100644 --- a/arch/arm/plat-orion/time.c +++ b/arch/arm/plat-orion/time.c @@ -17,6 +17,9 @@ #include #include #include +#include +#include +#include /* * Number of timer ticks per jiffy. @@ -38,6 +41,36 @@ static u32 ticks_per_jiffy; #define TIMER1_VAL (TIMER_VIRT_BASE + 0x001c) +/* + * Orion's sched_clock implementation. It has a resolution of + * at least 7.5ns (133MHz TCLK) and a maximum value of 834 days. + */ +#define TCLK2NS_SCALE_FACTOR 8 + +static unsigned long tclk2ns_scale; + +static void __init set_tclk2ns_scale(unsigned long tclk) +{ + unsigned long long v = NSEC_PER_SEC; + v <<= TCLK2NS_SCALE_FACTOR; + v += tclk/2; + do_div(v, tclk); + /* + * 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 (v & 1) + v++; + tclk2ns_scale = v; +} + +unsigned long long sched_clock(void) +{ + unsigned long long v = cnt32_to_63(0xffffffff - readl(TIMER0_VAL)); + return (v * tclk2ns_scale) >> TCLK2NS_SCALE_FACTOR; +} + /* * Clocksource handling. */ @@ -176,6 +209,10 @@ void __init orion_time_init(unsigned int irq, unsigned int tclk) ticks_per_jiffy = (tclk + HZ/2) / HZ; + /* + * Set scale for sched_clock + */ + set_tclk2ns_scale(tclk); /* * Setup free-running clocksource timer (interrupts -- cgit v1.2.1