Commit | Line | Data |
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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 | ||
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 | } | |
48 | ||
d0a533b1 WD |
49 | static void __timer_delay(unsigned long cycles) |
50 | { | |
51 | cycles_t start = get_cycles(); | |
52 | ||
53 | while ((get_cycles() - start) < cycles) | |
54 | cpu_relax(); | |
55 | } | |
56 | ||
57 | static void __timer_const_udelay(unsigned long xloops) | |
58 | { | |
59 | unsigned long long loops = xloops; | |
60 | loops *= loops_per_jiffy; | |
61 | __timer_delay(loops >> UDELAY_SHIFT); | |
62 | } | |
63 | ||
64 | static void __timer_udelay(unsigned long usecs) | |
65 | { | |
66 | __timer_const_udelay(usecs * UDELAY_MULT); | |
67 | } | |
68 | ||
56942fec | 69 | void __init register_current_timer_delay(const struct delay_timer *timer) |
d0a533b1 | 70 | { |
56942fec JA |
71 | if (!delay_calibrated) { |
72 | pr_info("Switching to timer-based delay loop\n"); | |
73 | delay_timer = timer; | |
74 | lpj_fine = timer->freq / HZ; | |
75 | loops_per_jiffy = lpj_fine; | |
76 | arm_delay_ops.delay = __timer_delay; | |
77 | arm_delay_ops.const_udelay = __timer_const_udelay; | |
78 | arm_delay_ops.udelay = __timer_udelay; | |
79 | delay_calibrated = true; | |
80 | } else { | |
81 | pr_info("Ignoring duplicate/late registration of read_current_timer delay\n"); | |
82 | } | |
d0a533b1 WD |
83 | } |
84 | ||
85 | unsigned long __cpuinit calibrate_delay_is_known(void) | |
86 | { | |
56942fec | 87 | delay_calibrated = true; |
d0a533b1 WD |
88 | return lpj_fine; |
89 | } |