[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/export.h>
#include <linux/timex.h>

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

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>
4dd1837d	27	#include <linux/export.h>
d0a533b1 WD	28	#include <linux/timex.h>
	29
	30	/*
	31	* Default to the loop-based delay implementation.
	32	*/
7619751f	33	struct arm_delay_ops arm_delay_ops __ro_after_init = {
d0a533b1 WD	34	.delay = __loop_delay,
	35	.const_udelay = __loop_const_udelay,
	36	.udelay = __loop_udelay,
	37	};
4dd1837d	38	EXPORT_SYMBOL(arm_delay_ops);
d0a533b1	39
56942fec JA	40	static const struct delay_timer *delay_timer;
56942fec JA	41	static bool delay_calibrated;
5930c1a1	42	static u64 delay_res;
56942fec JA	43
	44	int read_current_timer(unsigned long *timer_val)
	45	{
	46	if (!delay_timer)
	47	return -ENXIO;
	48
	49	*timer_val = delay_timer->read_current_timer();
	50	return 0;
	51	}
f3accb12	52	EXPORT_SYMBOL_GPL(read_current_timer);
56942fec	53
5930c1a1 PDS	54	static inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
	55	{
	56	return (cyc * mult) >> shift;
	57	}
	58
d0a533b1 WD	59	static void __timer_delay(unsigned long cycles)
	60	{
	61	cycles_t start = get_cycles();
	62
	63	while ((get_cycles() - start) < cycles)
	64	cpu_relax();
	65	}
	66
	67	static void __timer_const_udelay(unsigned long xloops)
	68	{
	69	unsigned long long loops = xloops;
6f3d90e5	70	loops *= arm_delay_ops.ticks_per_jiffy;
d0a533b1 WD	71	__timer_delay(loops >> UDELAY_SHIFT);
	72	}
	73
	74	static void __timer_udelay(unsigned long usecs)
	75	{
	76	__timer_const_udelay(usecs * UDELAY_MULT);
	77	}
	78
56942fec	79	void __init register_current_timer_delay(const struct delay_timer *timer)
d0a533b1	80	{
5930c1a1 PDS	81	u32 new_mult, new_shift;
	82	u64 res;
	83
	84	clocks_calc_mult_shift(&new_mult, &new_shift, timer->freq,
	85	NSEC_PER_SEC, 3600);
	86	res = cyc_to_ns(1ULL, new_mult, new_shift);
	87
57ca654b RK	88	if (res > 1000) {
	89	pr_err("Ignoring delay timer %ps, which has insufficient resolution of %lluns\n",
	90	timer, res);
	91	return;
	92	}
	93
5930c1a1 PDS	94	if (!delay_calibrated && (!delay_res \|\| (res < delay_res))) {
5930c1a1 PDS	95	pr_info("Switching to timer-based delay loop, resolution %lluns\n", res);
56942fec JA	96	delay_timer = timer;
56942fec JA	97	lpj_fine = timer->freq / HZ;
5930c1a1	98	delay_res = res;
6f3d90e5 WD	99
	100	/* cpufreq may scale loops_per_jiffy, so keep a private copy */
	101	arm_delay_ops.ticks_per_jiffy = lpj_fine;
56942fec JA	102	arm_delay_ops.delay = __timer_delay;
	103	arm_delay_ops.const_udelay = __timer_const_udelay;
	104	arm_delay_ops.udelay = __timer_udelay;
56942fec JA	105	} else {
	106	pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
	107	}
d0a533b1 WD	108	}
d0a533b1 WD	109
8bd26e3a	110	unsigned long calibrate_delay_is_known(void)
d0a533b1	111	{
56942fec	112	delay_calibrated = true;
d0a533b1 WD	113	return lpj_fine;
d0a533b1 WD	114	}
5930c1a1 PDS	115
	116	void calibration_delay_done(void)
	117	{
	118	delay_calibrated = true;
	119	}