[deliverable/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 <will.deacon@arm.com>
 */

#include <linux/clocksource.h>
#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;
static u64 delay_res;

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 inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
{
	return (cyc * mult) >> shift;
}

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)
{
	u32 new_mult, new_shift;
	u64 res;

	clocks_calc_mult_shift(&new_mult, &new_shift, timer->freq,
			       NSEC_PER_SEC, 3600);
	res = cyc_to_ns(1ULL, new_mult, new_shift);

	if (res > 1000) {
		pr_err("Ignoring delay timer %ps, which has insufficient resolution of %lluns\n",
			timer, res);
		return;
	}

	if (!delay_calibrated && (!delay_res || (res < delay_res))) {
		pr_info("Switching to timer-based delay loop, resolution %lluns\n", res);
		delay_timer			= timer;
		lpj_fine			= timer->freq / HZ;
		delay_res			= res;

		/* 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;
	} 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;
}

void calibration_delay_done(void)
{
	delay_calibrated = true;
}
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 <will.deacon@arm.com>
	20	*/
	21
5930c1a1	22	#include <linux/clocksource.h>
d0a533b1 WD	23	#include <linux/delay.h>
	24	#include <linux/init.h>
	25	#include <linux/kernel.h>
	26	#include <linux/module.h>
	27	#include <linux/timex.h>
	28
	29	/*
	30	* Default to the loop-based delay implementation.
	31	*/
	32	struct arm_delay_ops arm_delay_ops = {
	33	.delay = __loop_delay,
	34	.const_udelay = __loop_const_udelay,
	35	.udelay = __loop_udelay,
	36	};
	37
56942fec JA	38	static const struct delay_timer *delay_timer;
56942fec JA	39	static bool delay_calibrated;
5930c1a1	40	static u64 delay_res;
56942fec JA	41
	42	int read_current_timer(unsigned long *timer_val)
	43	{
	44	if (!delay_timer)
	45	return -ENXIO;
	46
	47	*timer_val = delay_timer->read_current_timer();
	48	return 0;
	49	}
f3accb12	50	EXPORT_SYMBOL_GPL(read_current_timer);
56942fec	51
5930c1a1 PDS	52	static inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
	53	{
	54	return (cyc * mult) >> shift;
	55	}
	56
d0a533b1 WD	57	static void __timer_delay(unsigned long cycles)
	58	{
	59	cycles_t start = get_cycles();
	60
	61	while ((get_cycles() - start) < cycles)
	62	cpu_relax();
	63	}
	64
	65	static void __timer_const_udelay(unsigned long xloops)
	66	{
	67	unsigned long long loops = xloops;
6f3d90e5	68	loops *= arm_delay_ops.ticks_per_jiffy;
d0a533b1 WD	69	__timer_delay(loops >> UDELAY_SHIFT);
	70	}
	71
	72	static void __timer_udelay(unsigned long usecs)
	73	{
	74	__timer_const_udelay(usecs * UDELAY_MULT);
	75	}
	76
56942fec	77	void __init register_current_timer_delay(const struct delay_timer *timer)
d0a533b1	78	{
5930c1a1 PDS	79	u32 new_mult, new_shift;
	80	u64 res;
	81
	82	clocks_calc_mult_shift(&new_mult, &new_shift, timer->freq,
	83	NSEC_PER_SEC, 3600);
	84	res = cyc_to_ns(1ULL, new_mult, new_shift);
	85
57ca654b RK	86	if (res > 1000) {
	87	pr_err("Ignoring delay timer %ps, which has insufficient resolution of %lluns\n",
	88	timer, res);
	89	return;
	90	}
	91
5930c1a1 PDS	92	if (!delay_calibrated && (!delay_res \|\| (res < delay_res))) {
5930c1a1 PDS	93	pr_info("Switching to timer-based delay loop, resolution %lluns\n", res);
56942fec JA	94	delay_timer = timer;
56942fec JA	95	lpj_fine = timer->freq / HZ;
5930c1a1	96	delay_res = res;
6f3d90e5 WD	97
	98	/* cpufreq may scale loops_per_jiffy, so keep a private copy */
	99	arm_delay_ops.ticks_per_jiffy = lpj_fine;
56942fec JA	100	arm_delay_ops.delay = __timer_delay;
	101	arm_delay_ops.const_udelay = __timer_const_udelay;
	102	arm_delay_ops.udelay = __timer_udelay;
56942fec JA	103	} else {
	104	pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
	105	}
d0a533b1 WD	106	}
d0a533b1 WD	107
8bd26e3a	108	unsigned long calibrate_delay_is_known(void)
d0a533b1	109	{
56942fec	110	delay_calibrated = true;
d0a533b1 WD	111	return lpj_fine;
d0a533b1 WD	112	}
5930c1a1 PDS	113
	114	void calibration_delay_done(void)
	115	{
	116	delay_calibrated = true;
	117	}