[linux.git] / arch / arm / lib / delay.c

/*
 * Delay loops based on the OpenRISC implementation.
 *
 * Copyright (C) 2012 ARM Limited
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Author: Will Deacon <[email protected]>
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/timex.h>

/*
 * Default to the loop-based delay implementation.
 */
struct arm_delay_ops arm_delay_ops = {
	.delay		= __loop_delay,
	.const_udelay	= __loop_const_udelay,
	.udelay		= __loop_udelay,
};

static const struct delay_timer *delay_timer;
static bool delay_calibrated;

int read_current_timer(unsigned long *timer_val)
{
	if (!delay_timer)
		return -ENXIO;

	*timer_val = delay_timer->read_current_timer();
	return 0;
}
EXPORT_SYMBOL_GPL(read_current_timer);

static void __timer_delay(unsigned long cycles)
{
	cycles_t start = get_cycles();

	while ((get_cycles() - start) < cycles)
		cpu_relax();
}

static void __timer_const_udelay(unsigned long xloops)
{
	unsigned long long loops = xloops;
	loops *= arm_delay_ops.ticks_per_jiffy;
	__timer_delay(loops >> UDELAY_SHIFT);
}

static void __timer_udelay(unsigned long usecs)
{
	__timer_const_udelay(usecs * UDELAY_MULT);
}

void __init register_current_timer_delay(const struct delay_timer *timer)
{
	if (!delay_calibrated) {
		pr_info("Switching to timer-based delay loop\n");
		delay_timer			= timer;
		lpj_fine			= timer->freq / HZ;

		/* cpufreq may scale loops_per_jiffy, so keep a private copy */
		arm_delay_ops.ticks_per_jiffy	= lpj_fine;
		arm_delay_ops.delay		= __timer_delay;
		arm_delay_ops.const_udelay	= __timer_const_udelay;
		arm_delay_ops.udelay		= __timer_udelay;

		delay_calibrated		= true;
	} else {
		pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
	}
}

unsigned long calibrate_delay_is_known(void)
{
	delay_calibrated = true;
	return lpj_fine;
}
Commit	Line	Data
d0a533b1 WD	1	/*
	2	* Delay loops based on the OpenRISC implementation.
	3	*
	4	* Copyright (C) 2012 ARM Limited
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	18	*
	19	* Author: Will Deacon <[email protected]>
	20	*/
	21
	22	#include <linux/delay.h>
	23	#include <linux/init.h>
	24	#include <linux/kernel.h>
	25	#include <linux/module.h>
	26	#include <linux/timex.h>
	27
	28	/*
	29	* Default to the loop-based delay implementation.
	30	*/
	31	struct arm_delay_ops arm_delay_ops = {
	32	.delay = __loop_delay,
	33	.const_udelay = __loop_const_udelay,
	34	.udelay = __loop_udelay,
	35	};
	36
56942fec JA	37	static const struct delay_timer *delay_timer;
	38	static bool delay_calibrated;
	39
	40	int read_current_timer(unsigned long *timer_val)
	41	{
	42	if (!delay_timer)
	43	return -ENXIO;
	44
	45	*timer_val = delay_timer->read_current_timer();
	46	return 0;
	47	}
f3accb12	48	EXPORT_SYMBOL_GPL(read_current_timer);
56942fec	49
d0a533b1 WD	50	static void __timer_delay(unsigned long cycles)
	51	{
	52	cycles_t start = get_cycles();
	53
	54	while ((get_cycles() - start) < cycles)
	55	cpu_relax();
	56	}
	57
	58	static void __timer_const_udelay(unsigned long xloops)
	59	{
	60	unsigned long long loops = xloops;
6f3d90e5	61	loops *= arm_delay_ops.ticks_per_jiffy;
d0a533b1 WD	62	__timer_delay(loops >> UDELAY_SHIFT);
	63	}
	64
	65	static void __timer_udelay(unsigned long usecs)
	66	{
	67	__timer_const_udelay(usecs * UDELAY_MULT);
	68	}
	69
56942fec	70	void __init register_current_timer_delay(const struct delay_timer *timer)
d0a533b1	71	{
56942fec JA	72	if (!delay_calibrated) {
	73	pr_info("Switching to timer-based delay loop\n");
	74	delay_timer = timer;
	75	lpj_fine = timer->freq / HZ;
6f3d90e5 WD	76
	77	/* cpufreq may scale loops_per_jiffy, so keep a private copy */
	78	arm_delay_ops.ticks_per_jiffy = lpj_fine;
56942fec JA	79	arm_delay_ops.delay = __timer_delay;
	80	arm_delay_ops.const_udelay = __timer_const_udelay;
	81	arm_delay_ops.udelay = __timer_udelay;
6f3d90e5	82
56942fec JA	83	delay_calibrated = true;
	84	} else {
	85	pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
	86	}
d0a533b1 WD	87	}
d0a533b1 WD	88
8bd26e3a	89	unsigned long calibrate_delay_is_known(void)
d0a533b1	90	{
56942fec	91	delay_calibrated = true;
d0a533b1 WD	92	return lpj_fine;
d0a533b1 WD	93	}