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Commit 85802afe authored by Catalin Marinas's avatar Catalin Marinas Committed by Russell King
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[ARM] 4811/1: RealView: clocksource support for the RealView platforms 



The patch updates the RealView platform code to use the generic
clocksource infrastructure for basic time keeping. Based on the
Versatile implementation by Kevin Hilman.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent ae9458d6

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -168,6 +168,7 @@ config ARCH_REALVIEW 
	bool "ARM Ltd. RealView family"

	select ARM_AMBA

	select ICST307

	select GENERIC_TIME

	help

	  This enables support for ARM Ltd RealView boards.

arch/arm/mach-realview/core.c

+31 −42
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ 
#include <linux/interrupt.h>

#include <linux/amba/bus.h>

#include <linux/amba/clcd.h>

#include <linux/clocksource.h>



#include <asm/system.h>

#include <asm/hardware.h>
@@ -484,47 +485,6 @@ void realview_leds_event(led_event_t ledevt) 
#define TICKS2USECS(x)	((x) / TICKS_PER_uSEC)

#endif



/*

 * Returns number of ms since last clock interrupt.  Note that interrupts

 * will have been disabled by do_gettimeoffset()

 */

static unsigned long realview_gettimeoffset(void)

{

	unsigned long ticks1, ticks2, status;



	/*

	 * 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.

	 */

	ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;

	do {

		ticks1 = ticks2;

		status = __raw_readl(__io_address(REALVIEW_GIC_DIST_BASE + GIC_DIST_PENDING_SET)

				     + ((IRQ_TIMERINT0_1 >> 5) << 2));

		ticks2 = readl(TIMER0_VA_BASE + TIMER_VALUE) & 0xffff;

	} while (ticks2 > ticks1);



	/*

	 * Number of ticks since last interrupt.

	 */

	ticks1 = TIMER_RELOAD - ticks2;



	/*

	 * Interrupt pending?  If so, we've reloaded once already.

	 *

	 * FIXME: Need to check this is effectively timer 0 that expires

	 */

	if (status & IRQMASK_TIMERINT0_1)

		ticks1 += TIMER_RELOAD;



	/*

	 * Convert the ticks to usecs

	 */

	return TICKS2USECS(ticks1);

}



/*

 * IRQ handler for the timer

 */
@@ -549,6 +509,34 @@ static struct irqaction realview_timer_irq = { 
	.handler	= realview_timer_interrupt,

};



static cycle_t realview_get_cycles(void)

{

	return ~readl(TIMER3_VA_BASE + TIMER_VALUE);

}



static struct clocksource clocksource_realview = {

	.name	= "timer3",

	.rating	= 200,

	.read	= realview_get_cycles,

	.mask	= CLOCKSOURCE_MASK(32),

	.shift	= 20,

	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,

};



static void __init realview_clocksource_init(void)

{

	/* setup timer 0 as free-running clocksource */

	writel(0, TIMER3_VA_BASE + TIMER_CTRL);

	writel(0xffffffff, TIMER3_VA_BASE + TIMER_LOAD);

	writel(0xffffffff, TIMER3_VA_BASE + TIMER_VALUE);

	writel(TIMER_CTRL_32BIT | TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC,

		TIMER3_VA_BASE + TIMER_CTRL);



	clocksource_realview.mult =

		clocksource_khz2mult(1000, clocksource_realview.shift);

	clocksource_register(&clocksource_realview);

}



/*

 * Set up timer interrupt, and return the current time in seconds.

 */
@@ -585,9 +573,10 @@ static void __init realview_timer_init(void) 
	 * Make irqs happen for the system timer

	 */

	setup_irq(IRQ_TIMERINT0_1, &realview_timer_irq);



	realview_clocksource_init();

}



struct sys_timer realview_timer = {

	.init		= realview_timer_init,

	.offset		= realview_gettimeoffset,

};