diff options
Diffstat (limited to 'arch/arm/plat-nomadik/timer.c')
| -rw-r--r-- | arch/arm/plat-nomadik/timer.c | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/arch/arm/plat-nomadik/timer.c b/arch/arm/plat-nomadik/timer.c index db67402518a6..0ff3798769ab 100644 --- a/arch/arm/plat-nomadik/timer.c +++ b/arch/arm/plat-nomadik/timer.c @@ -20,6 +20,15 @@ void __iomem *mtu_base; /* ssigned by machine code */ +/* + * Kernel assumes that sched_clock can be called early + * but the MTU may not yet be initialized. + */ +static cycle_t nmdk_read_timer_dummy(struct clocksource *cs) +{ + return 0; +} + /* clocksource: MTU decrements, so we negate the value being read. */ static cycle_t nmdk_read_timer(struct clocksource *cs) { @@ -29,12 +38,27 @@ static cycle_t nmdk_read_timer(struct clocksource *cs) static struct clocksource nmdk_clksrc = { .name = "mtu_0", .rating = 200, - .read = nmdk_read_timer, + .read = nmdk_read_timer_dummy, .mask = CLOCKSOURCE_MASK(32), .shift = 20, .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +/* + * Override the global weak sched_clock symbol with this + * local implementation which uses the clocksource to get some + * better resolution when scheduling the kernel. We accept that + * this wraps around for now, since it is just a relative time + * stamp. (Inspired by OMAP implementation.) + */ +unsigned long long notrace sched_clock(void) +{ + return clocksource_cyc2ns(nmdk_clksrc.read( + &nmdk_clksrc), + nmdk_clksrc.mult, + nmdk_clksrc.shift); +} + /* Clockevent device: use one-shot mode */ static void nmdk_clkevt_mode(enum clock_event_mode mode, struct clock_event_device *dev) @@ -121,6 +145,8 @@ void __init nmdk_timer_init(void) writel(cr | MTU_CRn_ENA, mtu_base + MTU_CR(0)); nmdk_clksrc.mult = clocksource_hz2mult(rate, nmdk_clksrc.shift); + /* Now the scheduling clock is ready */ + nmdk_clksrc.read = nmdk_read_timer; if (clocksource_register(&nmdk_clksrc)) pr_err("timer: failed to initialize clock source %s\n", |