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ARM: orion: implement ARM delay timer

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Implement an ARM delay timer to be used for udelay() on orion legacy
platforms.  This allows us to skip the delay loop calibration at boot.

It also means that udelay() will be unaffected by CPU frequency changes
when cpufreq is enabled on these platforms.

Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2015-10-19 16:00:35 +01:00
parent 92e963f50f
commit f19768ce0e
1 changed files with 13 additions and 0 deletions
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13
arch/arm/plat-orion/time.c
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@ -18,6 +18,7 @@
#include <linux/irq.h>
#include <linux/sched_clock.h>
#include <plat/time.h>
#include <asm/delay.h>
/*
* MBus bridge block registers.
@ -188,6 +189,15 @@ orion_time_set_base(void __iomem *_timer_base)
timer_base = _timer_base;
}
static unsigned long orion_delay_timer_read(void)
{
return ~readl(timer_base + TIMER0_VAL_OFF);
}
static struct delay_timer orion_delay_timer = {
.read_current_timer = orion_delay_timer_read,
};
void __init
orion_time_init(void __iomem *_bridge_base, u32 _bridge_timer1_clr_mask,
unsigned int irq, unsigned int tclk)
@ -202,6 +212,9 @@ orion_time_init(void __iomem *_bridge_base, u32 _bridge_timer1_clr_mask,
ticks_per_jiffy = (tclk + HZ/2) / HZ;
orion_delay_timer.freq = tclk;
register_current_timer_delay(&orion_delay_timer);
/*
* Set scale and timer for sched_clock.
*/