Commit 86987d5b authored by Pavel Pisa's avatar Pavel Pisa Committed by Russell King
Browse files

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



Enhanced resolution for time measurement functions.

Signed-off-by: default avatarPavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 5c894cd1

arch/arm/mach-imx/time.c

+50 −36
Original line number Diff line number Diff line
@@ -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))

	tstat = IMX_TSTAT(TIMER_BASE);

	IMX_TSTAT(TIMER_BASE) = 0;



	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,

};

include/asm-arm/arch-imx/timex.h

+1 −2
Original line number Diff line number Diff line
@@ -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