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clocksource/drivers/orion: Add delay_timer implementation 

Add an implementation for the ARM delay timer, which is used for
udelay().  This provides less CPU dependent and more accurate delays -
the CPU loop on Marvell Dove appears to calibrate to around 6% too
short.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Russell King 2017-03-11 17:42:34 +00:00 committed by Daniel Lezcano
parent 0d9298ea37
commit 9a4914ce0d
1 changed files with 19 additions and 0 deletions
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19
drivers/clocksource/time-orion.c
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@ -15,6 +15,7 @@
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
@ -36,6 +37,21 @@
static void __iomem *timer_base;
static unsigned long notrace orion_read_timer(void)
{
return ~readl(timer_base + TIMER0_VAL);
}
static struct delay_timer orion_delay_timer = {
.read_current_timer = orion_read_timer,
};
static void orion_delay_timer_init(unsigned long rate)
{
orion_delay_timer.freq = rate;
register_current_timer_delay(&orion_delay_timer);
}
/*
* Free-running clocksource handling.
*/
@ -168,6 +184,9 @@ static int __init orion_timer_init(struct device_node *np)
clockevents_config_and_register(&orion_clkevt, rate,
ORION_ONESHOT_MIN, ORION_ONESHOT_MAX);
orion_delay_timer_init(rate);
return 0;
}
CLOCKSOURCE_OF_DECLARE(orion_timer, "marvell,orion-timer", orion_timer_init);