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 | ||
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; |
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))) { |
95 | pr_info("Switching to timer-based delay loop, resolution %lluns\n", res); | |
56942fec JA |
96 | delay_timer = timer; |
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 | } |
109 | ||
8bd26e3a | 110 | unsigned long calibrate_delay_is_known(void) |
d0a533b1 | 111 | { |
56942fec | 112 | delay_calibrated = true; |
d0a533b1 WD |
113 | return lpj_fine; |
114 | } | |
5930c1a1 PDS |
115 | |
116 | void calibration_delay_done(void) | |
117 | { | |
118 | delay_calibrated = true; | |
119 | } |