Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 1 | /* |
| 2 | * sched_clock.c: support for extending counters to full 64-bit ns counter |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | #include <linux/clocksource.h> |
| 9 | #include <linux/init.h> |
| 10 | #include <linux/jiffies.h> |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 11 | #include <linux/ktime.h> |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 12 | #include <linux/kernel.h> |
Russell King | a42c362 | 2012-09-09 18:39:28 +0100 | [diff] [blame] | 13 | #include <linux/moduleparam.h> |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 14 | #include <linux/sched.h> |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 15 | #include <linux/syscore_ops.h> |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 16 | #include <linux/hrtimer.h> |
Stephen Boyd | 38ff87f | 2013-06-01 23:39:40 -0700 | [diff] [blame] | 17 | #include <linux/sched_clock.h> |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 18 | #include <linux/seqlock.h> |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 19 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 20 | struct clock_data { |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 21 | ktime_t wrap_kt; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 22 | u64 epoch_ns; |
| 23 | u32 epoch_cyc; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 24 | seqcount_t seq; |
Rob Herring | c115739 | 2013-02-08 16:14:59 -0600 | [diff] [blame] | 25 | unsigned long rate; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 26 | u32 mult; |
| 27 | u32 shift; |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 28 | bool suspended; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 29 | }; |
| 30 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 31 | static struct hrtimer sched_clock_timer; |
Russell King | a42c362 | 2012-09-09 18:39:28 +0100 | [diff] [blame] | 32 | static int irqtime = -1; |
| 33 | |
| 34 | core_param(irqtime, irqtime, int, 0400); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 35 | |
| 36 | static struct clock_data cd = { |
| 37 | .mult = NSEC_PER_SEC / HZ, |
| 38 | }; |
| 39 | |
| 40 | static u32 __read_mostly sched_clock_mask = 0xffffffff; |
| 41 | |
| 42 | static u32 notrace jiffy_sched_clock_read(void) |
| 43 | { |
| 44 | return (u32)(jiffies - INITIAL_JIFFIES); |
| 45 | } |
| 46 | |
| 47 | static u32 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read; |
| 48 | |
Stephen Boyd | cea1509 | 2013-04-18 17:33:40 +0100 | [diff] [blame] | 49 | static inline u64 notrace cyc_to_ns(u64 cyc, u32 mult, u32 shift) |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 50 | { |
| 51 | return (cyc * mult) >> shift; |
| 52 | } |
| 53 | |
Stephen Boyd | 336ae11 | 2013-06-17 15:40:58 -0700 | [diff] [blame] | 54 | static unsigned long long notrace sched_clock_32(void) |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 55 | { |
| 56 | u64 epoch_ns; |
| 57 | u32 epoch_cyc; |
Stephen Boyd | 336ae11 | 2013-06-17 15:40:58 -0700 | [diff] [blame] | 58 | u32 cyc; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 59 | unsigned long seq; |
Stephen Boyd | 336ae11 | 2013-06-17 15:40:58 -0700 | [diff] [blame] | 60 | |
| 61 | if (cd.suspended) |
| 62 | return cd.epoch_ns; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 63 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 64 | do { |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 65 | seq = read_seqcount_begin(&cd.seq); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 66 | epoch_cyc = cd.epoch_cyc; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 67 | epoch_ns = cd.epoch_ns; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 68 | } while (read_seqcount_retry(&cd.seq, seq)); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 69 | |
Stephen Boyd | 336ae11 | 2013-06-17 15:40:58 -0700 | [diff] [blame] | 70 | cyc = read_sched_clock(); |
| 71 | cyc = (cyc - epoch_cyc) & sched_clock_mask; |
| 72 | return epoch_ns + cyc_to_ns(cyc, cd.mult, cd.shift); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 73 | } |
| 74 | |
| 75 | /* |
| 76 | * Atomically update the sched_clock epoch. |
| 77 | */ |
| 78 | static void notrace update_sched_clock(void) |
| 79 | { |
| 80 | unsigned long flags; |
| 81 | u32 cyc; |
| 82 | u64 ns; |
| 83 | |
| 84 | cyc = read_sched_clock(); |
| 85 | ns = cd.epoch_ns + |
| 86 | cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask, |
| 87 | cd.mult, cd.shift); |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 88 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 89 | raw_local_irq_save(flags); |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 90 | write_seqcount_begin(&cd.seq); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 91 | cd.epoch_ns = ns; |
Joonsoo Kim | 7c4e9ce | 2013-02-09 05:52:45 +0100 | [diff] [blame] | 92 | cd.epoch_cyc = cyc; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 93 | write_seqcount_end(&cd.seq); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 94 | raw_local_irq_restore(flags); |
| 95 | } |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 96 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 97 | static enum hrtimer_restart sched_clock_poll(struct hrtimer *hrt) |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 98 | { |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 99 | update_sched_clock(); |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 100 | hrtimer_forward_now(hrt, cd.wrap_kt); |
| 101 | return HRTIMER_RESTART; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 102 | } |
| 103 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 104 | void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate) |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 105 | { |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 106 | unsigned long r; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 107 | u64 res, wrap; |
| 108 | char r_unit; |
| 109 | |
Rob Herring | c115739 | 2013-02-08 16:14:59 -0600 | [diff] [blame] | 110 | if (cd.rate > rate) |
| 111 | return; |
| 112 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 113 | BUG_ON(bits > 32); |
| 114 | WARN_ON(!irqs_disabled()); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 115 | read_sched_clock = read; |
| 116 | sched_clock_mask = (1 << bits) - 1; |
Rob Herring | c115739 | 2013-02-08 16:14:59 -0600 | [diff] [blame] | 117 | cd.rate = rate; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 118 | |
| 119 | /* calculate the mult/shift to convert counter ticks to ns. */ |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 120 | clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 121 | |
| 122 | r = rate; |
| 123 | if (r >= 4000000) { |
| 124 | r /= 1000000; |
| 125 | r_unit = 'M'; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 126 | } else if (r >= 1000) { |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 127 | r /= 1000; |
| 128 | r_unit = 'k'; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 129 | } else |
| 130 | r_unit = ' '; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 131 | |
| 132 | /* calculate how many ns until we wrap */ |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 133 | wrap = cyc_to_ns((1ULL << bits) - 1, cd.mult, cd.shift); |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 134 | cd.wrap_kt = ns_to_ktime(wrap - (wrap >> 3)); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 135 | |
| 136 | /* calculate the ns resolution of this counter */ |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 137 | res = cyc_to_ns(1ULL, cd.mult, cd.shift); |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 138 | pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lluns\n", |
| 139 | bits, r, r_unit, res, wrap); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 140 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 141 | update_sched_clock(); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 142 | |
| 143 | /* |
| 144 | * Ensure that sched_clock() starts off at 0ns |
| 145 | */ |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 146 | cd.epoch_ns = 0; |
| 147 | |
Russell King | a42c362 | 2012-09-09 18:39:28 +0100 | [diff] [blame] | 148 | /* Enable IRQ time accounting if we have a fast enough sched_clock */ |
| 149 | if (irqtime > 0 || (irqtime == -1 && rate >= 1000000)) |
| 150 | enable_sched_clock_irqtime(); |
| 151 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 152 | pr_debug("Registered %pF as sched_clock source\n", read); |
| 153 | } |
| 154 | |
Rob Herring | 7e48c0b | 2013-04-01 13:53:38 -0500 | [diff] [blame] | 155 | unsigned long long __read_mostly (*sched_clock_func)(void) = sched_clock_32; |
| 156 | |
| 157 | unsigned long long notrace sched_clock(void) |
| 158 | { |
| 159 | return sched_clock_func(); |
| 160 | } |
| 161 | |
Russell King | 211baa70 | 2011-01-11 16:23:04 +0000 | [diff] [blame] | 162 | void __init sched_clock_postinit(void) |
| 163 | { |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 164 | /* |
| 165 | * If no sched_clock function has been provided at that point, |
| 166 | * make it the final one one. |
| 167 | */ |
| 168 | if (read_sched_clock == jiffy_sched_clock_read) |
| 169 | setup_sched_clock(jiffy_sched_clock_read, 32, HZ); |
| 170 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 171 | update_sched_clock(); |
| 172 | |
| 173 | /* |
| 174 | * Start the timer to keep sched_clock() properly updated and |
| 175 | * sets the initial epoch. |
| 176 | */ |
| 177 | hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 178 | sched_clock_timer.function = sched_clock_poll; |
| 179 | hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); |
Russell King | 211baa70 | 2011-01-11 16:23:04 +0000 | [diff] [blame] | 180 | } |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 181 | |
| 182 | static int sched_clock_suspend(void) |
| 183 | { |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame^] | 184 | sched_clock_poll(&sched_clock_timer); |
Felipe Balbi 2 | 6a4dae5 | 2012-10-23 19:00:03 +0100 | [diff] [blame] | 185 | cd.suspended = true; |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 186 | return 0; |
| 187 | } |
| 188 | |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 189 | static void sched_clock_resume(void) |
| 190 | { |
Felipe Balbi 2 | 6a4dae5 | 2012-10-23 19:00:03 +0100 | [diff] [blame] | 191 | cd.epoch_cyc = read_sched_clock(); |
Felipe Balbi 2 | 6a4dae5 | 2012-10-23 19:00:03 +0100 | [diff] [blame] | 192 | cd.suspended = false; |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 193 | } |
| 194 | |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 195 | static struct syscore_ops sched_clock_ops = { |
| 196 | .suspend = sched_clock_suspend, |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 197 | .resume = sched_clock_resume, |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 198 | }; |
| 199 | |
| 200 | static int __init sched_clock_syscore_init(void) |
| 201 | { |
| 202 | register_syscore_ops(&sched_clock_ops); |
| 203 | return 0; |
| 204 | } |
| 205 | device_initcall(sched_clock_syscore_init); |