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> |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 19 | #include <linux/bitops.h> |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 20 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 21 | struct clock_data { |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 22 | ktime_t wrap_kt; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 23 | u64 epoch_ns; |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 24 | u64 epoch_cyc; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 25 | seqcount_t seq; |
Rob Herring | c115739 | 2013-02-08 16:14:59 -0600 | [diff] [blame] | 26 | unsigned long rate; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 27 | u32 mult; |
| 28 | u32 shift; |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 29 | bool suspended; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 30 | }; |
| 31 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 32 | static struct hrtimer sched_clock_timer; |
Russell King | a42c362 | 2012-09-09 18:39:28 +0100 | [diff] [blame] | 33 | static int irqtime = -1; |
| 34 | |
| 35 | core_param(irqtime, irqtime, int, 0400); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 36 | |
| 37 | static struct clock_data cd = { |
| 38 | .mult = NSEC_PER_SEC / HZ, |
| 39 | }; |
| 40 | |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 41 | static u64 __read_mostly sched_clock_mask; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 42 | |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 43 | static u64 notrace jiffy_sched_clock_read(void) |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 44 | { |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 45 | /* |
| 46 | * We don't need to use get_jiffies_64 on 32-bit arches here |
| 47 | * because we register with BITS_PER_LONG |
| 48 | */ |
| 49 | return (u64)(jiffies - INITIAL_JIFFIES); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 50 | } |
| 51 | |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 52 | static u64 __read_mostly (*read_sched_clock)(void) = jiffy_sched_clock_read; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 53 | |
Stephen Boyd | cea1509 | 2013-04-18 17:33:40 +0100 | [diff] [blame] | 54 | 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] | 55 | { |
| 56 | return (cyc * mult) >> shift; |
| 57 | } |
| 58 | |
Stephen Boyd | b4042ce | 2013-07-18 16:21:19 -0700 | [diff] [blame] | 59 | unsigned long long notrace sched_clock(void) |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 60 | { |
| 61 | u64 epoch_ns; |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 62 | u64 epoch_cyc; |
| 63 | u64 cyc; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 64 | unsigned long seq; |
Stephen Boyd | 336ae11 | 2013-06-17 15:40:58 -0700 | [diff] [blame] | 65 | |
| 66 | if (cd.suspended) |
| 67 | return cd.epoch_ns; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 68 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 69 | do { |
John Stultz | 7a06c41 | 2014-01-02 15:11:14 -0800 | [diff] [blame] | 70 | seq = raw_read_seqcount_begin(&cd.seq); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 71 | epoch_cyc = cd.epoch_cyc; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 72 | epoch_ns = cd.epoch_ns; |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 73 | } while (read_seqcount_retry(&cd.seq, seq)); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 74 | |
Stephen Boyd | 336ae11 | 2013-06-17 15:40:58 -0700 | [diff] [blame] | 75 | cyc = read_sched_clock(); |
| 76 | cyc = (cyc - epoch_cyc) & sched_clock_mask; |
| 77 | return epoch_ns + cyc_to_ns(cyc, cd.mult, cd.shift); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 78 | } |
| 79 | |
| 80 | /* |
| 81 | * Atomically update the sched_clock epoch. |
| 82 | */ |
| 83 | static void notrace update_sched_clock(void) |
| 84 | { |
| 85 | unsigned long flags; |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 86 | u64 cyc; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 87 | u64 ns; |
| 88 | |
| 89 | cyc = read_sched_clock(); |
| 90 | ns = cd.epoch_ns + |
| 91 | cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask, |
| 92 | cd.mult, cd.shift); |
Stephen Boyd | 85c3d2d | 2013-07-18 16:21:15 -0700 | [diff] [blame] | 93 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 94 | raw_local_irq_save(flags); |
John Stultz | 7a06c41 | 2014-01-02 15:11:14 -0800 | [diff] [blame] | 95 | raw_write_seqcount_begin(&cd.seq); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 96 | cd.epoch_ns = ns; |
Joonsoo Kim | 7c4e9ce | 2013-02-09 05:52:45 +0100 | [diff] [blame] | 97 | cd.epoch_cyc = cyc; |
John Stultz | 7a06c41 | 2014-01-02 15:11:14 -0800 | [diff] [blame] | 98 | raw_write_seqcount_end(&cd.seq); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 99 | raw_local_irq_restore(flags); |
| 100 | } |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 101 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 102 | static enum hrtimer_restart sched_clock_poll(struct hrtimer *hrt) |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 103 | { |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 104 | update_sched_clock(); |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 105 | hrtimer_forward_now(hrt, cd.wrap_kt); |
| 106 | return HRTIMER_RESTART; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 107 | } |
| 108 | |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 109 | void __init sched_clock_register(u64 (*read)(void), int bits, |
| 110 | unsigned long rate) |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 111 | { |
Stephen Boyd | 5ae8aab | 2014-02-17 10:45:36 -0800 | [diff] [blame] | 112 | u64 res, wrap, new_mask, new_epoch, cyc, ns; |
| 113 | u32 new_mult, new_shift; |
| 114 | ktime_t new_wrap_kt; |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 115 | unsigned long r; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 116 | char r_unit; |
| 117 | |
Rob Herring | c115739 | 2013-02-08 16:14:59 -0600 | [diff] [blame] | 118 | if (cd.rate > rate) |
| 119 | return; |
| 120 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 121 | WARN_ON(!irqs_disabled()); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 122 | |
| 123 | /* calculate the mult/shift to convert counter ticks to ns. */ |
Stephen Boyd | 5ae8aab | 2014-02-17 10:45:36 -0800 | [diff] [blame] | 124 | clocks_calc_mult_shift(&new_mult, &new_shift, rate, NSEC_PER_SEC, 3600); |
| 125 | |
| 126 | new_mask = CLOCKSOURCE_MASK(bits); |
| 127 | |
| 128 | /* calculate how many ns until we wrap */ |
| 129 | wrap = clocks_calc_max_nsecs(new_mult, new_shift, 0, new_mask); |
| 130 | new_wrap_kt = ns_to_ktime(wrap - (wrap >> 3)); |
| 131 | |
| 132 | /* update epoch for new counter and update epoch_ns from old counter*/ |
| 133 | new_epoch = read(); |
| 134 | cyc = read_sched_clock(); |
| 135 | ns = cd.epoch_ns + cyc_to_ns((cyc - cd.epoch_cyc) & sched_clock_mask, |
| 136 | cd.mult, cd.shift); |
| 137 | |
| 138 | raw_write_seqcount_begin(&cd.seq); |
| 139 | read_sched_clock = read; |
| 140 | sched_clock_mask = new_mask; |
| 141 | cd.rate = rate; |
| 142 | cd.wrap_kt = new_wrap_kt; |
| 143 | cd.mult = new_mult; |
| 144 | cd.shift = new_shift; |
| 145 | cd.epoch_cyc = new_epoch; |
| 146 | cd.epoch_ns = ns; |
| 147 | raw_write_seqcount_end(&cd.seq); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 148 | |
| 149 | r = rate; |
| 150 | if (r >= 4000000) { |
| 151 | r /= 1000000; |
| 152 | r_unit = 'M'; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 153 | } else if (r >= 1000) { |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 154 | r /= 1000; |
| 155 | r_unit = 'k'; |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 156 | } else |
| 157 | r_unit = ' '; |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 158 | |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 159 | /* calculate the ns resolution of this counter */ |
Stephen Boyd | 5ae8aab | 2014-02-17 10:45:36 -0800 | [diff] [blame] | 160 | res = cyc_to_ns(1ULL, new_mult, new_shift); |
| 161 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 162 | pr_info("sched_clock: %u bits at %lu%cHz, resolution %lluns, wraps every %lluns\n", |
| 163 | bits, r, r_unit, res, wrap); |
Russell King | 112f38a4 | 2010-12-15 19:23:07 +0000 | [diff] [blame] | 164 | |
Russell King | a42c362 | 2012-09-09 18:39:28 +0100 | [diff] [blame] | 165 | /* Enable IRQ time accounting if we have a fast enough sched_clock */ |
| 166 | if (irqtime > 0 || (irqtime == -1 && rate >= 1000000)) |
| 167 | enable_sched_clock_irqtime(); |
| 168 | |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 169 | pr_debug("Registered %pF as sched_clock source\n", read); |
| 170 | } |
| 171 | |
Russell King | 211baa70 | 2011-01-11 16:23:04 +0000 | [diff] [blame] | 172 | void __init sched_clock_postinit(void) |
| 173 | { |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 174 | /* |
| 175 | * If no sched_clock function has been provided at that point, |
| 176 | * make it the final one one. |
| 177 | */ |
| 178 | if (read_sched_clock == jiffy_sched_clock_read) |
Stephen Boyd | e7e3ff1 | 2013-07-18 16:21:17 -0700 | [diff] [blame] | 179 | sched_clock_register(jiffy_sched_clock_read, BITS_PER_LONG, HZ); |
Marc Zyngier | 2f0778af | 2011-12-15 12:19:23 +0100 | [diff] [blame] | 180 | |
Stephen Boyd | a08ca5d | 2013-07-18 16:21:16 -0700 | [diff] [blame] | 181 | update_sched_clock(); |
| 182 | |
| 183 | /* |
| 184 | * Start the timer to keep sched_clock() properly updated and |
| 185 | * sets the initial epoch. |
| 186 | */ |
| 187 | hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 188 | sched_clock_timer.function = sched_clock_poll; |
| 189 | hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); |
Russell King | 211baa70 | 2011-01-11 16:23:04 +0000 | [diff] [blame] | 190 | } |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 191 | |
| 192 | static int sched_clock_suspend(void) |
| 193 | { |
Stephen Boyd | f723aa1 | 2014-07-23 21:03:50 -0700 | [diff] [blame] | 194 | update_sched_clock(); |
| 195 | hrtimer_cancel(&sched_clock_timer); |
Felipe Balbi 2 | 6a4dae5 | 2012-10-23 19:00:03 +0100 | [diff] [blame] | 196 | cd.suspended = true; |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 197 | return 0; |
| 198 | } |
| 199 | |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 200 | static void sched_clock_resume(void) |
| 201 | { |
Felipe Balbi 2 | 6a4dae5 | 2012-10-23 19:00:03 +0100 | [diff] [blame] | 202 | cd.epoch_cyc = read_sched_clock(); |
Stephen Boyd | f723aa1 | 2014-07-23 21:03:50 -0700 | [diff] [blame] | 203 | hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); |
Felipe Balbi 2 | 6a4dae5 | 2012-10-23 19:00:03 +0100 | [diff] [blame] | 204 | cd.suspended = false; |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 205 | } |
| 206 | |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 207 | static struct syscore_ops sched_clock_ops = { |
| 208 | .suspend = sched_clock_suspend, |
Colin Cross | 237ec6f | 2012-08-07 19:05:10 +0100 | [diff] [blame] | 209 | .resume = sched_clock_resume, |
Russell King | f153d01 | 2012-02-04 12:31:27 +0000 | [diff] [blame] | 210 | }; |
| 211 | |
| 212 | static int __init sched_clock_syscore_init(void) |
| 213 | { |
| 214 | register_syscore_ops(&sched_clock_ops); |
| 215 | return 0; |
| 216 | } |
| 217 | device_initcall(sched_clock_syscore_init); |