clocksource/drivers/orion: Add delay_timer implementation

#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>

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.

 */

	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);