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[ARM] 3991/1: i.MX/MX1 high resolution time source

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Enhanced resolution for time measurement functions.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Pavel Pisa 2006-12-06 17:19:44 +01:00 committed by Russell King
parent 5c894cd1c8
commit 86987d5bf4
2 changed files with 51 additions and 38 deletions
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86
arch/arm/mach-imx/time.c
View File

@ -14,6 +14,7 @@
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/time.h>
#include <linux/clocksource.h>
#include <asm/hardware.h>
#include <asm/io.h>
@ -24,33 +25,7 @@
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
/*
* Returns number of us since last clock interrupt. Note that interrupts
* will have been disabled by do_gettimeoffset()
*/
static unsigned long imx_gettimeoffset(void)
{
unsigned long ticks;
/*
* Get the current number of ticks. Note that there is a race
* condition between us reading the timer and checking for
* an interrupt. We get around this by ensuring that the
* counter has not reloaded between our two reads.
*/
ticks = IMX_TCN(TIMER_BASE);
/*
* Interrupt pending? If so, we've reloaded once already.
*/
if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP)
ticks += LATCH;
/*
* Convert the ticks to usecs
*/
return (1000000 / CLK32) * ticks;
}
static unsigned long evt_diff;
/*
* IRQ handler for the timer
@ -58,14 +33,23 @@ static unsigned long imx_gettimeoffset(void)
static irqreturn_t
imx_timer_interrupt(int irq, void *dev_id)
{
write_seqlock(&xtime_lock);
uint32_t tstat;
/* clear the interrupt */
if (IMX_TSTAT(TIMER_BASE))
IMX_TSTAT(TIMER_BASE) = 0;
tstat = IMX_TSTAT(TIMER_BASE);
IMX_TSTAT(TIMER_BASE) = 0;
timer_tick();
write_sequnlock(&xtime_lock);
if (tstat & TSTAT_COMP) {
do {
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
IMX_TCMP(TIMER_BASE) += evt_diff;
} while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
- IMX_TCN(TIMER_BASE)) < 0));
}
return IRQ_HANDLED;
}
@ -77,9 +61,9 @@ static struct irqaction imx_timer_irq = {
};
/*
* Set up timer interrupt, and return the current time in seconds.
* Set up timer hardware into expected mode and state.
*/
static void __init imx_timer_init(void)
static void __init imx_timer_hardware_init(void)
{
/*
* Initialise to a known state (all timers off, and timing reset)
@ -87,7 +71,38 @@ static void __init imx_timer_init(void)
IMX_TCTL(TIMER_BASE) = 0;
IMX_TPRER(TIMER_BASE) = 0;
IMX_TCMP(TIMER_BASE) = LATCH - 1;
IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN;
IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
evt_diff = LATCH;
}
cycle_t imx_get_cycles(void)
{
return IMX_TCN(TIMER_BASE);
}
static struct clocksource clocksource_imx = {
.name = "imx_timer1",
.rating = 200,
.read = imx_get_cycles,
.mask = 0xFFFFFFFF,
.shift = 20,
.is_continuous = 1,
};
static int __init imx_clocksource_init(void)
{
clocksource_imx.mult =
clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift);
clocksource_register(&clocksource_imx);
return 0;
}
static void __init imx_timer_init(void)
{
imx_timer_hardware_init();
imx_clocksource_init();
/*
* Make irqs happen for the system timer
@ -97,5 +112,4 @@ static void __init imx_timer_init(void)
struct sys_timer imx_timer = {
.init = imx_timer_init,
.offset = imx_gettimeoffset,
};

3
include/asm-arm/arch-imx/timex.h
View File

@ -21,7 +21,6 @@
#ifndef __ASM_ARCH_TIMEX_H
#define __ASM_ARCH_TIMEX_H
#include <asm/hardware.h>
#define CLOCK_TICK_RATE (CLK32)
#define CLOCK_TICK_RATE (16000000)
#endif