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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: Daniel 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: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Linus Walleij 2017-06-11 23:26:16 +02:00 committed by Daniel Lezcano
parent 8b7a3b5688
commit 740e237add
1 changed files with 10 additions and 5 deletions
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15
drivers/clocksource/timer-fttmr010.c
View File

@ -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_up, 32,
fttmr010->tick_rate);
}
sched_clock_register(fttmr010_read_sched_clock, 32,
fttmr010->tick_rate);
/*
* Setup clockevent timer (interrupt-driven) on timer 1.