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Commit 740e237a authored by Linus Walleij's avatar Linus Walleij Committed by Daniel Lezcano
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clocksource/drivers/fttmr010: Optimize sched_clock() 



The sched_clock() call should be really fast so we want to
avoid an extra if() clause on the read path if possible.

Implement two sched_clock_read() functions, one if the timer
counts up and one if it counts down. Incidentally this also
mirrors how clocksource_mmio_init() works and make things
simple and easy to understand.

Suggested-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Jonas Jensen <jonas.jensen@gmail.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent 8b7a3b56

drivers/clocksource/timer-fttmr010.c

+10 −5
Original line number Diff line number Diff line
@@ -91,13 +91,16 @@ static inline struct fttmr010 *to_fttmr010(struct clock_event_device *evt) 
	return container_of(evt, struct fttmr010, clkevt);

}



static u64 notrace fttmr010_read_sched_clock(void)

static u64 notrace fttmr010_read_sched_clock_up(void)

{

	if (local_fttmr->count_down)

		return ~readl(local_fttmr->base + TIMER2_COUNT);

	return readl(local_fttmr->base + TIMER2_COUNT);

}



static u64 notrace fttmr010_read_sched_clock_down(void)

{

	return ~readl(local_fttmr->base + TIMER2_COUNT);

}



static int fttmr010_timer_set_next_event(unsigned long cycles,

				       struct clock_event_device *evt)

{
@@ -302,15 +305,17 @@ static int __init fttmr010_common_init(struct device_node *np, bool is_aspeed) 
				      "FTTMR010-TIMER2",

				      fttmr010->tick_rate,

				      300, 32, clocksource_mmio_readl_down);

		sched_clock_register(fttmr010_read_sched_clock_down, 32,

				     fttmr010->tick_rate);

	} else {

		writel(0, fttmr010->base + TIMER2_LOAD);

		clocksource_mmio_init(fttmr010->base + TIMER2_COUNT,

				      "FTTMR010-TIMER2",

				      fttmr010->tick_rate,

				      300, 32, clocksource_mmio_readl_up);

	}

	sched_clock_register(fttmr010_read_sched_clock, 32,

		sched_clock_register(fttmr010_read_sched_clock_up, 32,

				     fttmr010->tick_rate);

	}



	/*

	 * Setup clockevent timer (interrupt-driven) on timer 1.