blob: 5306de35013397994ec6873f2a713af5d47867a4 [file] [log] [blame]
Will Deacond0a533b2012-07-06 15:47:17 +01001/*
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
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 */
31struct arm_delay_ops arm_delay_ops = {
32 .delay = __loop_delay,
33 .const_udelay = __loop_const_udelay,
34 .udelay = __loop_udelay,
35};
36
Jonathan Austin56942fe2012-09-21 18:51:44 +010037static const struct delay_timer *delay_timer;
38static bool delay_calibrated;
39
40int 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}
Arnd Bergmannf3accb12012-10-01 14:47:31 +000048EXPORT_SYMBOL_GPL(read_current_timer);
Jonathan Austin56942fe2012-09-21 18:51:44 +010049
Will Deacond0a533b2012-07-06 15:47:17 +010050static 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
58static void __timer_const_udelay(unsigned long xloops)
59{
60 unsigned long long loops = xloops;
Will Deacon6f3d90e2013-03-28 11:17:55 +010061 loops *= arm_delay_ops.ticks_per_jiffy;
Will Deacond0a533b2012-07-06 15:47:17 +010062 __timer_delay(loops >> UDELAY_SHIFT);
63}
64
65static void __timer_udelay(unsigned long usecs)
66{
67 __timer_const_udelay(usecs * UDELAY_MULT);
68}
69
Jonathan Austin56942fe2012-09-21 18:51:44 +010070void __init register_current_timer_delay(const struct delay_timer *timer)
Will Deacond0a533b2012-07-06 15:47:17 +010071{
Jonathan Austin56942fe2012-09-21 18:51:44 +010072 if (!delay_calibrated) {
73 pr_info("Switching to timer-based delay loop\n");
74 delay_timer = timer;
75 lpj_fine = timer->freq / HZ;
Will Deacon6f3d90e2013-03-28 11:17:55 +010076
77 /* cpufreq may scale loops_per_jiffy, so keep a private copy */
78 arm_delay_ops.ticks_per_jiffy = lpj_fine;
Jonathan Austin56942fe2012-09-21 18:51:44 +010079 arm_delay_ops.delay = __timer_delay;
80 arm_delay_ops.const_udelay = __timer_const_udelay;
81 arm_delay_ops.udelay = __timer_udelay;
Will Deacon6f3d90e2013-03-28 11:17:55 +010082
Jonathan Austin56942fe2012-09-21 18:51:44 +010083 delay_calibrated = true;
84 } else {
85 pr_info("Ignoring duplicate/late registration of read_current_timer delay\n");
86 }
Will Deacond0a533b2012-07-06 15:47:17 +010087}
88
Paul Gortmaker8bd26e32013-06-17 15:43:14 -040089unsigned long calibrate_delay_is_known(void)
Will Deacond0a533b2012-07-06 15:47:17 +010090{
Jonathan Austin56942fe2012-09-21 18:51:44 +010091 delay_calibrated = true;
Will Deacond0a533b2012-07-06 15:47:17 +010092 return lpj_fine;
93}