xtensa: implement ccount calibration for s6000

	bool "s6000 - Stretch software configurable processor"

	select VARIANT_IRQ_SWITCH

	select ARCH_REQUIRE_GPIOLIB

	select XTENSA_CALIBRATE_CCOUNT

endchoice

config XTENSA_UNALIGNED_USER

# s6000 Makefile

obj-y		+= irq.o gpio.o

obj-$(CONFIG_XTENSA_CALIBRATE_CCOUNT)	+= delay.o

#include <asm/delay.h>

#include <asm/timex.h>

#include <asm/io.h>

#include <variant/hardware.h>

#define LOOPS 10

void platform_calibrate_ccount(void)

{

	u32 uninitialized_var(a);

	u32 uninitialized_var(u);

	u32 b;

	u32 tstamp = S6_REG_GREG1 + S6_GREG1_GLOBAL_TIMER;

	int i = LOOPS+1;

	do {

		u32 t = u;

		asm volatile(

		"1:	l32i %0, %2, 0 ;"

		"	beq %0, %1, 1b ;"

		: "=&a"(u) : "a"(t), "a"(tstamp));

		b = xtensa_get_ccount();

		if (i == LOOPS)

			a = b;

	} while (--i >= 0);

	b -= a;

	nsec_per_ccount = (LOOPS * 10000) / b;

	ccount_per_jiffy = b * (100000UL / (LOOPS * HZ));

}