CooCenter-System-kernel/arch/cris/arch-v32/lib/delay.c

/*
 * Precise Delay Loops for ETRAX FS
 *
 * Copyright (C) 2006 Axis Communications AB.
 *
 */

#include <hwregs/reg_map.h>
#include <hwregs/reg_rdwr.h>
#include <hwregs/timer_defs.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/module.h>

/*
 * On ETRAX FS, we can check the free-running read-only 100MHz timer
 * getting 32-bit 10ns precision, theoretically good for 42.94967295
 * seconds.  Unsigned arithmetic and careful expression handles
 * wrapping.
 */

void cris_delay10ns(u32 n10ns)
{
	u32 t0 = REG_RD(timer, regi_timer0, r_time);
	while (REG_RD(timer, regi_timer0, r_time) - t0 < n10ns)
		;
}
EXPORT_SYMBOL(cris_delay10ns);