john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/time/clocksource.c |
| 3 | * |
| 4 | * This file contains the functions which manage clocksource drivers. |
| 5 | * |
| 6 | * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License as published by |
| 10 | * the Free Software Foundation; either version 2 of the License, or |
| 11 | * (at your option) any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU General Public License |
| 19 | * along with this program; if not, write to the Free Software |
| 20 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
| 21 | * |
| 22 | * TODO WishList: |
| 23 | * o Allow clocksource drivers to be unregistered |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 24 | */ |
| 25 | |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 26 | #include <linux/device.h> |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 27 | #include <linux/clocksource.h> |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 28 | #include <linux/init.h> |
| 29 | #include <linux/module.h> |
Mathieu Desnoyers | dc29a36 | 2007-02-10 01:43:43 -0800 | [diff] [blame] | 30 | #include <linux/sched.h> /* for spin_unlock_irq() using preempt_count() m68k */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 31 | #include <linux/tick.h> |
Martin Schwidefsky | 01548f4 | 2009-08-18 17:09:42 +0200 | [diff] [blame] | 32 | #include <linux/kthread.h> |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 33 | |
Thomas Gleixner | 03e13cf | 2013-04-25 20:31:50 +0000 | [diff] [blame] | 34 | #include "tick-internal.h" |
| 35 | |
Patrick Ohly | a038a35 | 2009-02-12 05:03:34 +0000 | [diff] [blame] | 36 | void timecounter_init(struct timecounter *tc, |
| 37 | const struct cyclecounter *cc, |
| 38 | u64 start_tstamp) |
| 39 | { |
| 40 | tc->cc = cc; |
| 41 | tc->cycle_last = cc->read(cc); |
| 42 | tc->nsec = start_tstamp; |
| 43 | } |
David S. Miller | 3586e0a | 2009-11-11 19:06:30 -0800 | [diff] [blame] | 44 | EXPORT_SYMBOL_GPL(timecounter_init); |
Patrick Ohly | a038a35 | 2009-02-12 05:03:34 +0000 | [diff] [blame] | 45 | |
| 46 | /** |
| 47 | * timecounter_read_delta - get nanoseconds since last call of this function |
| 48 | * @tc: Pointer to time counter |
| 49 | * |
| 50 | * When the underlying cycle counter runs over, this will be handled |
| 51 | * correctly as long as it does not run over more than once between |
| 52 | * calls. |
| 53 | * |
| 54 | * The first call to this function for a new time counter initializes |
| 55 | * the time tracking and returns an undefined result. |
| 56 | */ |
| 57 | static u64 timecounter_read_delta(struct timecounter *tc) |
| 58 | { |
| 59 | cycle_t cycle_now, cycle_delta; |
| 60 | u64 ns_offset; |
| 61 | |
| 62 | /* read cycle counter: */ |
| 63 | cycle_now = tc->cc->read(tc->cc); |
| 64 | |
| 65 | /* calculate the delta since the last timecounter_read_delta(): */ |
| 66 | cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask; |
| 67 | |
| 68 | /* convert to nanoseconds: */ |
| 69 | ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta); |
| 70 | |
| 71 | /* update time stamp of timecounter_read_delta() call: */ |
| 72 | tc->cycle_last = cycle_now; |
| 73 | |
| 74 | return ns_offset; |
| 75 | } |
| 76 | |
| 77 | u64 timecounter_read(struct timecounter *tc) |
| 78 | { |
| 79 | u64 nsec; |
| 80 | |
| 81 | /* increment time by nanoseconds since last call */ |
| 82 | nsec = timecounter_read_delta(tc); |
| 83 | nsec += tc->nsec; |
| 84 | tc->nsec = nsec; |
| 85 | |
| 86 | return nsec; |
| 87 | } |
David S. Miller | 3586e0a | 2009-11-11 19:06:30 -0800 | [diff] [blame] | 88 | EXPORT_SYMBOL_GPL(timecounter_read); |
Patrick Ohly | a038a35 | 2009-02-12 05:03:34 +0000 | [diff] [blame] | 89 | |
| 90 | u64 timecounter_cyc2time(struct timecounter *tc, |
| 91 | cycle_t cycle_tstamp) |
| 92 | { |
| 93 | u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask; |
| 94 | u64 nsec; |
| 95 | |
| 96 | /* |
| 97 | * Instead of always treating cycle_tstamp as more recent |
| 98 | * than tc->cycle_last, detect when it is too far in the |
| 99 | * future and treat it as old time stamp instead. |
| 100 | */ |
| 101 | if (cycle_delta > tc->cc->mask / 2) { |
| 102 | cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask; |
| 103 | nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta); |
| 104 | } else { |
| 105 | nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec; |
| 106 | } |
| 107 | |
| 108 | return nsec; |
| 109 | } |
David S. Miller | 3586e0a | 2009-11-11 19:06:30 -0800 | [diff] [blame] | 110 | EXPORT_SYMBOL_GPL(timecounter_cyc2time); |
Patrick Ohly | a038a35 | 2009-02-12 05:03:34 +0000 | [diff] [blame] | 111 | |
Thomas Gleixner | 7d2f944 | 2009-11-11 14:05:29 +0000 | [diff] [blame] | 112 | /** |
| 113 | * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks |
| 114 | * @mult: pointer to mult variable |
| 115 | * @shift: pointer to shift variable |
| 116 | * @from: frequency to convert from |
| 117 | * @to: frequency to convert to |
Nicolas Pitre | 5fdade9 | 2011-01-11 12:18:12 -0500 | [diff] [blame] | 118 | * @maxsec: guaranteed runtime conversion range in seconds |
Thomas Gleixner | 7d2f944 | 2009-11-11 14:05:29 +0000 | [diff] [blame] | 119 | * |
| 120 | * The function evaluates the shift/mult pair for the scaled math |
| 121 | * operations of clocksources and clockevents. |
| 122 | * |
| 123 | * @to and @from are frequency values in HZ. For clock sources @to is |
| 124 | * NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock |
| 125 | * event @to is the counter frequency and @from is NSEC_PER_SEC. |
| 126 | * |
Nicolas Pitre | 5fdade9 | 2011-01-11 12:18:12 -0500 | [diff] [blame] | 127 | * The @maxsec conversion range argument controls the time frame in |
Thomas Gleixner | 7d2f944 | 2009-11-11 14:05:29 +0000 | [diff] [blame] | 128 | * seconds which must be covered by the runtime conversion with the |
| 129 | * calculated mult and shift factors. This guarantees that no 64bit |
| 130 | * overflow happens when the input value of the conversion is |
| 131 | * multiplied with the calculated mult factor. Larger ranges may |
| 132 | * reduce the conversion accuracy by chosing smaller mult and shift |
| 133 | * factors. |
| 134 | */ |
| 135 | void |
Nicolas Pitre | 5fdade9 | 2011-01-11 12:18:12 -0500 | [diff] [blame] | 136 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 maxsec) |
Thomas Gleixner | 7d2f944 | 2009-11-11 14:05:29 +0000 | [diff] [blame] | 137 | { |
| 138 | u64 tmp; |
| 139 | u32 sft, sftacc= 32; |
| 140 | |
| 141 | /* |
| 142 | * Calculate the shift factor which is limiting the conversion |
| 143 | * range: |
| 144 | */ |
Nicolas Pitre | 5fdade9 | 2011-01-11 12:18:12 -0500 | [diff] [blame] | 145 | tmp = ((u64)maxsec * from) >> 32; |
Thomas Gleixner | 7d2f944 | 2009-11-11 14:05:29 +0000 | [diff] [blame] | 146 | while (tmp) { |
| 147 | tmp >>=1; |
| 148 | sftacc--; |
| 149 | } |
| 150 | |
| 151 | /* |
| 152 | * Find the conversion shift/mult pair which has the best |
| 153 | * accuracy and fits the maxsec conversion range: |
| 154 | */ |
| 155 | for (sft = 32; sft > 0; sft--) { |
| 156 | tmp = (u64) to << sft; |
john stultz | b5776c4 | 2010-12-16 19:03:27 +0000 | [diff] [blame] | 157 | tmp += from / 2; |
Thomas Gleixner | 7d2f944 | 2009-11-11 14:05:29 +0000 | [diff] [blame] | 158 | do_div(tmp, from); |
| 159 | if ((tmp >> sftacc) == 0) |
| 160 | break; |
| 161 | } |
| 162 | *mult = tmp; |
| 163 | *shift = sft; |
| 164 | } |
| 165 | |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 166 | /*[Clocksource internal variables]--------- |
| 167 | * curr_clocksource: |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 168 | * currently selected clocksource. |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 169 | * clocksource_list: |
| 170 | * linked list with the registered clocksources |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 171 | * clocksource_mutex: |
| 172 | * protects manipulations to curr_clocksource and the clocksource_list |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 173 | * override_name: |
| 174 | * Name of the user-specified clocksource. |
| 175 | */ |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 176 | static struct clocksource *curr_clocksource; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 177 | static LIST_HEAD(clocksource_list); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 178 | static DEFINE_MUTEX(clocksource_mutex); |
Thomas Gleixner | 29b54078 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 179 | static char override_name[CS_NAME_LEN]; |
Thomas Gleixner | 54a6bc0 | 2009-09-14 19:49:02 +0200 | [diff] [blame] | 180 | static int finished_booting; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 181 | |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 182 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
Martin Schwidefsky | f79e025 | 2009-09-11 15:33:05 +0200 | [diff] [blame] | 183 | static void clocksource_watchdog_work(struct work_struct *work); |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 184 | static void clocksource_select(void); |
Martin Schwidefsky | f79e025 | 2009-09-11 15:33:05 +0200 | [diff] [blame] | 185 | |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 186 | static LIST_HEAD(watchdog_list); |
| 187 | static struct clocksource *watchdog; |
| 188 | static struct timer_list watchdog_timer; |
Martin Schwidefsky | f79e025 | 2009-09-11 15:33:05 +0200 | [diff] [blame] | 189 | static DECLARE_WORK(watchdog_work, clocksource_watchdog_work); |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 190 | static DEFINE_SPINLOCK(watchdog_lock); |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 191 | static int watchdog_running; |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 192 | static atomic_t watchdog_reset_pending; |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 193 | |
Martin Schwidefsky | 01548f4 | 2009-08-18 17:09:42 +0200 | [diff] [blame] | 194 | static int clocksource_watchdog_kthread(void *data); |
Thomas Gleixner | d0981a1 | 2009-08-19 11:26:09 +0200 | [diff] [blame] | 195 | static void __clocksource_change_rating(struct clocksource *cs, int rating); |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 196 | |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 197 | /* |
Daniel Walker | 35c35d1 | 2007-05-09 02:33:40 -0700 | [diff] [blame] | 198 | * Interval: 0.5sec Threshold: 0.0625s |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 199 | */ |
| 200 | #define WATCHDOG_INTERVAL (HZ >> 1) |
Daniel Walker | 35c35d1 | 2007-05-09 02:33:40 -0700 | [diff] [blame] | 201 | #define WATCHDOG_THRESHOLD (NSEC_PER_SEC >> 4) |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 202 | |
Martin Schwidefsky | 01548f4 | 2009-08-18 17:09:42 +0200 | [diff] [blame] | 203 | static void clocksource_watchdog_work(struct work_struct *work) |
| 204 | { |
| 205 | /* |
| 206 | * If kthread_run fails the next watchdog scan over the |
| 207 | * watchdog_list will find the unstable clock again. |
| 208 | */ |
| 209 | kthread_run(clocksource_watchdog_kthread, NULL, "kwatchdog"); |
| 210 | } |
| 211 | |
Thomas Gleixner | 7285dd7 | 2009-08-28 20:25:24 +0200 | [diff] [blame] | 212 | static void __clocksource_unstable(struct clocksource *cs) |
| 213 | { |
| 214 | cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); |
| 215 | cs->flags |= CLOCK_SOURCE_UNSTABLE; |
Thomas Gleixner | 54a6bc0 | 2009-09-14 19:49:02 +0200 | [diff] [blame] | 216 | if (finished_booting) |
| 217 | schedule_work(&watchdog_work); |
Thomas Gleixner | 7285dd7 | 2009-08-28 20:25:24 +0200 | [diff] [blame] | 218 | } |
| 219 | |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 220 | static void clocksource_unstable(struct clocksource *cs, int64_t delta) |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 221 | { |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 222 | printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", |
| 223 | cs->name, delta); |
Thomas Gleixner | 7285dd7 | 2009-08-28 20:25:24 +0200 | [diff] [blame] | 224 | __clocksource_unstable(cs); |
| 225 | } |
| 226 | |
| 227 | /** |
| 228 | * clocksource_mark_unstable - mark clocksource unstable via watchdog |
| 229 | * @cs: clocksource to be marked unstable |
| 230 | * |
| 231 | * This function is called instead of clocksource_change_rating from |
| 232 | * cpu hotplug code to avoid a deadlock between the clocksource mutex |
| 233 | * and the cpu hotplug mutex. It defers the update of the clocksource |
| 234 | * to the watchdog thread. |
| 235 | */ |
| 236 | void clocksource_mark_unstable(struct clocksource *cs) |
| 237 | { |
| 238 | unsigned long flags; |
| 239 | |
| 240 | spin_lock_irqsave(&watchdog_lock, flags); |
| 241 | if (!(cs->flags & CLOCK_SOURCE_UNSTABLE)) { |
| 242 | if (list_empty(&cs->wd_list)) |
| 243 | list_add(&cs->wd_list, &watchdog_list); |
| 244 | __clocksource_unstable(cs); |
| 245 | } |
| 246 | spin_unlock_irqrestore(&watchdog_lock, flags); |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 247 | } |
| 248 | |
| 249 | static void clocksource_watchdog(unsigned long data) |
| 250 | { |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 251 | struct clocksource *cs; |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 252 | cycle_t csnow, wdnow; |
| 253 | int64_t wd_nsec, cs_nsec; |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 254 | int next_cpu, reset_pending; |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 255 | |
| 256 | spin_lock(&watchdog_lock); |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 257 | if (!watchdog_running) |
| 258 | goto out; |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 259 | |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 260 | reset_pending = atomic_read(&watchdog_reset_pending); |
| 261 | |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 262 | list_for_each_entry(cs, &watchdog_list, wd_list) { |
| 263 | |
| 264 | /* Clocksource already marked unstable? */ |
Martin Schwidefsky | 01548f4 | 2009-08-18 17:09:42 +0200 | [diff] [blame] | 265 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
Thomas Gleixner | 54a6bc0 | 2009-09-14 19:49:02 +0200 | [diff] [blame] | 266 | if (finished_booting) |
| 267 | schedule_work(&watchdog_work); |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 268 | continue; |
Martin Schwidefsky | 01548f4 | 2009-08-18 17:09:42 +0200 | [diff] [blame] | 269 | } |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 270 | |
Thomas Gleixner | b519951 | 2011-06-16 16:22:08 +0200 | [diff] [blame] | 271 | local_irq_disable(); |
Magnus Damm | 8e19608 | 2009-04-21 12:24:00 -0700 | [diff] [blame] | 272 | csnow = cs->read(cs); |
Thomas Gleixner | b519951 | 2011-06-16 16:22:08 +0200 | [diff] [blame] | 273 | wdnow = watchdog->read(watchdog); |
| 274 | local_irq_enable(); |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 275 | |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 276 | /* Clocksource initialized ? */ |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 277 | if (!(cs->flags & CLOCK_SOURCE_WATCHDOG) || |
| 278 | atomic_read(&watchdog_reset_pending)) { |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 279 | cs->flags |= CLOCK_SOURCE_WATCHDOG; |
Thomas Gleixner | b519951 | 2011-06-16 16:22:08 +0200 | [diff] [blame] | 280 | cs->wd_last = wdnow; |
| 281 | cs->cs_last = csnow; |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 282 | continue; |
| 283 | } |
| 284 | |
Thomas Gleixner | b519951 | 2011-06-16 16:22:08 +0200 | [diff] [blame] | 285 | wd_nsec = clocksource_cyc2ns((wdnow - cs->wd_last) & watchdog->mask, |
| 286 | watchdog->mult, watchdog->shift); |
| 287 | |
| 288 | cs_nsec = clocksource_cyc2ns((csnow - cs->cs_last) & |
Martin Schwidefsky | 155ec60 | 2009-08-14 15:47:26 +0200 | [diff] [blame] | 289 | cs->mask, cs->mult, cs->shift); |
Thomas Gleixner | b519951 | 2011-06-16 16:22:08 +0200 | [diff] [blame] | 290 | cs->cs_last = csnow; |
| 291 | cs->wd_last = wdnow; |
| 292 | |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 293 | if (atomic_read(&watchdog_reset_pending)) |
| 294 | continue; |
| 295 | |
Thomas Gleixner | b519951 | 2011-06-16 16:22:08 +0200 | [diff] [blame] | 296 | /* Check the deviation from the watchdog clocksource. */ |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 297 | if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) { |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 298 | clocksource_unstable(cs, cs_nsec - wd_nsec); |
| 299 | continue; |
| 300 | } |
| 301 | |
| 302 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && |
| 303 | (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && |
| 304 | (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 305 | /* Mark it valid for high-res. */ |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 306 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 307 | |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 308 | /* |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 309 | * clocksource_done_booting() will sort it if |
| 310 | * finished_booting is not set yet. |
Martin Schwidefsky | 8cf4e75 | 2009-08-14 15:47:22 +0200 | [diff] [blame] | 311 | */ |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 312 | if (!finished_booting) |
| 313 | continue; |
| 314 | |
| 315 | /* |
| 316 | * If this is not the current clocksource let |
| 317 | * the watchdog thread reselect it. Due to the |
| 318 | * change to high res this clocksource might |
| 319 | * be preferred now. If it is the current |
| 320 | * clocksource let the tick code know about |
| 321 | * that change. |
| 322 | */ |
| 323 | if (cs != curr_clocksource) { |
| 324 | cs->flags |= CLOCK_SOURCE_RESELECT; |
| 325 | schedule_work(&watchdog_work); |
| 326 | } else { |
| 327 | tick_clock_notify(); |
| 328 | } |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 329 | } |
| 330 | } |
| 331 | |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 332 | /* |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 333 | * We only clear the watchdog_reset_pending, when we did a |
| 334 | * full cycle through all clocksources. |
| 335 | */ |
| 336 | if (reset_pending) |
| 337 | atomic_dec(&watchdog_reset_pending); |
| 338 | |
| 339 | /* |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 340 | * Cycle through CPUs to check if the CPUs stay synchronized |
| 341 | * to each other. |
| 342 | */ |
| 343 | next_cpu = cpumask_next(raw_smp_processor_id(), cpu_online_mask); |
| 344 | if (next_cpu >= nr_cpu_ids) |
| 345 | next_cpu = cpumask_first(cpu_online_mask); |
| 346 | watchdog_timer.expires += WATCHDOG_INTERVAL; |
| 347 | add_timer_on(&watchdog_timer, next_cpu); |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 348 | out: |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 349 | spin_unlock(&watchdog_lock); |
| 350 | } |
Martin Schwidefsky | 0f8e8ef | 2009-08-14 15:47:23 +0200 | [diff] [blame] | 351 | |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 352 | static inline void clocksource_start_watchdog(void) |
| 353 | { |
| 354 | if (watchdog_running || !watchdog || list_empty(&watchdog_list)) |
| 355 | return; |
| 356 | init_timer(&watchdog_timer); |
| 357 | watchdog_timer.function = clocksource_watchdog; |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 358 | watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; |
| 359 | add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask)); |
| 360 | watchdog_running = 1; |
| 361 | } |
| 362 | |
| 363 | static inline void clocksource_stop_watchdog(void) |
| 364 | { |
| 365 | if (!watchdog_running || (watchdog && !list_empty(&watchdog_list))) |
| 366 | return; |
| 367 | del_timer(&watchdog_timer); |
| 368 | watchdog_running = 0; |
| 369 | } |
| 370 | |
Martin Schwidefsky | 0f8e8ef | 2009-08-14 15:47:23 +0200 | [diff] [blame] | 371 | static inline void clocksource_reset_watchdog(void) |
| 372 | { |
| 373 | struct clocksource *cs; |
| 374 | |
| 375 | list_for_each_entry(cs, &watchdog_list, wd_list) |
| 376 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
| 377 | } |
| 378 | |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 379 | static void clocksource_resume_watchdog(void) |
| 380 | { |
Thomas Gleixner | 9fb6033 | 2011-09-12 13:32:23 +0200 | [diff] [blame] | 381 | atomic_inc(&watchdog_reset_pending); |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 382 | } |
| 383 | |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 384 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 385 | { |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 386 | unsigned long flags; |
| 387 | |
| 388 | spin_lock_irqsave(&watchdog_lock, flags); |
| 389 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 390 | /* cs is a clocksource to be watched. */ |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 391 | list_add(&cs->wd_list, &watchdog_list); |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 392 | cs->flags &= ~CLOCK_SOURCE_WATCHDOG; |
Thomas Gleixner | 948ac6d | 2007-03-25 14:42:51 +0200 | [diff] [blame] | 393 | } else { |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 394 | /* cs is a watchdog. */ |
Thomas Gleixner | 948ac6d | 2007-03-25 14:42:51 +0200 | [diff] [blame] | 395 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 396 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 397 | /* Pick the best watchdog. */ |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 398 | if (!watchdog || cs->rating > watchdog->rating) { |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 399 | watchdog = cs; |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 400 | /* Reset watchdog cycles */ |
Martin Schwidefsky | 0f8e8ef | 2009-08-14 15:47:23 +0200 | [diff] [blame] | 401 | clocksource_reset_watchdog(); |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 402 | } |
| 403 | } |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 404 | /* Check if the watchdog timer needs to be started. */ |
| 405 | clocksource_start_watchdog(); |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 406 | spin_unlock_irqrestore(&watchdog_lock, flags); |
| 407 | } |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 408 | |
| 409 | static void clocksource_dequeue_watchdog(struct clocksource *cs) |
| 410 | { |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 411 | unsigned long flags; |
| 412 | |
| 413 | spin_lock_irqsave(&watchdog_lock, flags); |
Thomas Gleixner | a89c7ed | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 414 | if (cs != watchdog) { |
| 415 | if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { |
| 416 | /* cs is a watched clocksource. */ |
| 417 | list_del_init(&cs->wd_list); |
| 418 | /* Check if the watchdog timer needs to be stopped. */ |
| 419 | clocksource_stop_watchdog(); |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 420 | } |
| 421 | } |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 422 | spin_unlock_irqrestore(&watchdog_lock, flags); |
| 423 | } |
| 424 | |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 425 | static int __clocksource_watchdog_kthread(void) |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 426 | { |
| 427 | struct clocksource *cs, *tmp; |
| 428 | unsigned long flags; |
Thomas Gleixner | 6ea41d2 | 2009-08-15 13:20:42 +0200 | [diff] [blame] | 429 | LIST_HEAD(unstable); |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 430 | int select = 0; |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 431 | |
| 432 | spin_lock_irqsave(&watchdog_lock, flags); |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 433 | list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 434 | if (cs->flags & CLOCK_SOURCE_UNSTABLE) { |
| 435 | list_del_init(&cs->wd_list); |
Thomas Gleixner | 6ea41d2 | 2009-08-15 13:20:42 +0200 | [diff] [blame] | 436 | list_add(&cs->wd_list, &unstable); |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 437 | select = 1; |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 438 | } |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 439 | if (cs->flags & CLOCK_SOURCE_RESELECT) { |
| 440 | cs->flags &= ~CLOCK_SOURCE_RESELECT; |
| 441 | select = 1; |
| 442 | } |
| 443 | } |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 444 | /* Check if the watchdog timer needs to be stopped. */ |
| 445 | clocksource_stop_watchdog(); |
Thomas Gleixner | 6ea41d2 | 2009-08-15 13:20:42 +0200 | [diff] [blame] | 446 | spin_unlock_irqrestore(&watchdog_lock, flags); |
| 447 | |
| 448 | /* Needs to be done outside of watchdog lock */ |
| 449 | list_for_each_entry_safe(cs, tmp, &unstable, wd_list) { |
| 450 | list_del_init(&cs->wd_list); |
Thomas Gleixner | d0981a1 | 2009-08-19 11:26:09 +0200 | [diff] [blame] | 451 | __clocksource_change_rating(cs, 0); |
Thomas Gleixner | 6ea41d2 | 2009-08-15 13:20:42 +0200 | [diff] [blame] | 452 | } |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 453 | return select; |
| 454 | } |
| 455 | |
| 456 | static int clocksource_watchdog_kthread(void *data) |
| 457 | { |
| 458 | mutex_lock(&clocksource_mutex); |
| 459 | if (__clocksource_watchdog_kthread()) |
| 460 | clocksource_select(); |
Thomas Gleixner | d0981a1 | 2009-08-19 11:26:09 +0200 | [diff] [blame] | 461 | mutex_unlock(&clocksource_mutex); |
Martin Schwidefsky | 01548f4 | 2009-08-18 17:09:42 +0200 | [diff] [blame] | 462 | return 0; |
Martin Schwidefsky | c55c87c | 2009-08-14 15:47:25 +0200 | [diff] [blame] | 463 | } |
| 464 | |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 465 | static bool clocksource_is_watchdog(struct clocksource *cs) |
| 466 | { |
| 467 | return cs == watchdog; |
| 468 | } |
| 469 | |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 470 | #else /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
| 471 | |
| 472 | static void clocksource_enqueue_watchdog(struct clocksource *cs) |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 473 | { |
| 474 | if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) |
| 475 | cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; |
| 476 | } |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 477 | |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 478 | static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { } |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 479 | static inline void clocksource_resume_watchdog(void) { } |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 480 | static inline int __clocksource_watchdog_kthread(void) { return 0; } |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 481 | static bool clocksource_is_watchdog(struct clocksource *cs) { return false; } |
Prarit Bhargava | 397bbf6 | 2013-02-22 15:08:56 -0500 | [diff] [blame] | 482 | void clocksource_mark_unstable(struct clocksource *cs) { } |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 483 | |
| 484 | #endif /* CONFIG_CLOCKSOURCE_WATCHDOG */ |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 485 | |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 486 | /** |
Magnus Damm | c54a42b | 2010-02-02 14:41:41 -0800 | [diff] [blame] | 487 | * clocksource_suspend - suspend the clocksource(s) |
| 488 | */ |
| 489 | void clocksource_suspend(void) |
| 490 | { |
| 491 | struct clocksource *cs; |
| 492 | |
| 493 | list_for_each_entry_reverse(cs, &clocksource_list, list) |
| 494 | if (cs->suspend) |
| 495 | cs->suspend(cs); |
| 496 | } |
| 497 | |
| 498 | /** |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 499 | * clocksource_resume - resume the clocksource(s) |
| 500 | */ |
| 501 | void clocksource_resume(void) |
| 502 | { |
Matthias Kaehlcke | 2e19758 | 2007-10-18 23:39:58 -0700 | [diff] [blame] | 503 | struct clocksource *cs; |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 504 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 505 | list_for_each_entry(cs, &clocksource_list, list) |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 506 | if (cs->resume) |
Magnus Damm | 1762233 | 2010-02-02 14:41:39 -0800 | [diff] [blame] | 507 | cs->resume(cs); |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 508 | |
| 509 | clocksource_resume_watchdog(); |
Thomas Gleixner | b52f52a | 2007-05-09 02:35:15 -0700 | [diff] [blame] | 510 | } |
| 511 | |
| 512 | /** |
Jason Wessel | 7c3078b | 2008-02-15 14:55:54 -0600 | [diff] [blame] | 513 | * clocksource_touch_watchdog - Update watchdog |
| 514 | * |
| 515 | * Update the watchdog after exception contexts such as kgdb so as not |
Thomas Gleixner | 7b7422a | 2010-01-26 12:51:10 +0100 | [diff] [blame] | 516 | * to incorrectly trip the watchdog. This might fail when the kernel |
| 517 | * was stopped in code which holds watchdog_lock. |
Jason Wessel | 7c3078b | 2008-02-15 14:55:54 -0600 | [diff] [blame] | 518 | */ |
| 519 | void clocksource_touch_watchdog(void) |
| 520 | { |
| 521 | clocksource_resume_watchdog(); |
| 522 | } |
| 523 | |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 524 | /** |
John Stultz | d65670a | 2011-10-31 17:06:35 -0400 | [diff] [blame] | 525 | * clocksource_max_adjustment- Returns max adjustment amount |
| 526 | * @cs: Pointer to clocksource |
| 527 | * |
| 528 | */ |
| 529 | static u32 clocksource_max_adjustment(struct clocksource *cs) |
| 530 | { |
| 531 | u64 ret; |
| 532 | /* |
Jim Cromie | 88b28ad | 2012-03-14 21:28:56 -0600 | [diff] [blame] | 533 | * We won't try to correct for more than 11% adjustments (110,000 ppm), |
John Stultz | d65670a | 2011-10-31 17:06:35 -0400 | [diff] [blame] | 534 | */ |
| 535 | ret = (u64)cs->mult * 11; |
| 536 | do_div(ret,100); |
| 537 | return (u32)ret; |
| 538 | } |
| 539 | |
| 540 | /** |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 541 | * clocks_calc_max_nsecs - Returns maximum nanoseconds that can be converted |
| 542 | * @mult: cycle to nanosecond multiplier |
| 543 | * @shift: cycle to nanosecond divisor (power of two) |
| 544 | * @maxadj: maximum adjustment value to mult (~11%) |
| 545 | * @mask: bitmask for two's complement subtraction of non 64 bit counters |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 546 | */ |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 547 | u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask) |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 548 | { |
| 549 | u64 max_nsecs, max_cycles; |
| 550 | |
| 551 | /* |
| 552 | * Calculate the maximum number of cycles that we can pass to the |
| 553 | * cyc2ns function without overflowing a 64-bit signed result. The |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 554 | * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj) |
John Stultz | d65670a | 2011-10-31 17:06:35 -0400 | [diff] [blame] | 555 | * which is equivalent to the below. |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 556 | * max_cycles < (2^63)/(mult + maxadj) |
| 557 | * max_cycles < 2^(log2((2^63)/(mult + maxadj))) |
| 558 | * max_cycles < 2^(log2(2^63) - log2(mult + maxadj)) |
| 559 | * max_cycles < 2^(63 - log2(mult + maxadj)) |
| 560 | * max_cycles < 1 << (63 - log2(mult + maxadj)) |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 561 | * Please note that we add 1 to the result of the log2 to account for |
| 562 | * any rounding errors, ensure the above inequality is satisfied and |
| 563 | * no overflow will occur. |
| 564 | */ |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 565 | max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1)); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 566 | |
| 567 | /* |
| 568 | * The actual maximum number of cycles we can defer the clocksource is |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 569 | * determined by the minimum of max_cycles and mask. |
John Stultz | d65670a | 2011-10-31 17:06:35 -0400 | [diff] [blame] | 570 | * Note: Here we subtract the maxadj to make sure we don't sleep for |
| 571 | * too long if there's a large negative adjustment. |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 572 | */ |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 573 | max_cycles = min(max_cycles, mask); |
| 574 | max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 575 | |
Stephen Boyd | 87d8b9e | 2013-07-18 16:21:14 -0700 | [diff] [blame] | 576 | return max_nsecs; |
| 577 | } |
| 578 | |
| 579 | /** |
| 580 | * clocksource_max_deferment - Returns max time the clocksource can be deferred |
| 581 | * @cs: Pointer to clocksource |
| 582 | * |
| 583 | */ |
| 584 | static u64 clocksource_max_deferment(struct clocksource *cs) |
| 585 | { |
| 586 | u64 max_nsecs; |
| 587 | |
| 588 | max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj, |
| 589 | cs->mask); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 590 | /* |
| 591 | * To ensure that the clocksource does not wrap whilst we are idle, |
| 592 | * limit the time the clocksource can be deferred by 12.5%. Please |
| 593 | * note a margin of 12.5% is used because this can be computed with |
| 594 | * a shift, versus say 10% which would require division. |
| 595 | */ |
Yang Honggang (Joseph) | b1f9196 | 2011-12-01 22:22:41 -0500 | [diff] [blame] | 596 | return max_nsecs - (max_nsecs >> 3); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 597 | } |
| 598 | |
John Stultz | 592913e | 2010-07-13 17:56:20 -0700 | [diff] [blame] | 599 | #ifndef CONFIG_ARCH_USES_GETTIMEOFFSET |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 600 | |
Thomas Gleixner | f5a2e34 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 601 | static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur) |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 602 | { |
| 603 | struct clocksource *cs; |
| 604 | |
| 605 | if (!finished_booting || list_empty(&clocksource_list)) |
| 606 | return NULL; |
| 607 | |
| 608 | /* |
| 609 | * We pick the clocksource with the highest rating. If oneshot |
| 610 | * mode is active, we pick the highres valid clocksource with |
| 611 | * the best rating. |
| 612 | */ |
| 613 | list_for_each_entry(cs, &clocksource_list, list) { |
Thomas Gleixner | f5a2e34 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 614 | if (skipcur && cs == curr_clocksource) |
| 615 | continue; |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 616 | if (oneshot && !(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
| 617 | continue; |
| 618 | return cs; |
| 619 | } |
| 620 | return NULL; |
| 621 | } |
| 622 | |
Thomas Gleixner | f5a2e34 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 623 | static void __clocksource_select(bool skipcur) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 624 | { |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 625 | bool oneshot = tick_oneshot_mode_active(); |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 626 | struct clocksource *best, *cs; |
Thomas Gleixner | 5d8b34f | 2007-02-16 01:27:43 -0800 | [diff] [blame] | 627 | |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 628 | /* Find the best suitable clocksource */ |
Thomas Gleixner | f5a2e34 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 629 | best = clocksource_find_best(oneshot, skipcur); |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 630 | if (!best) |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 631 | return; |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 632 | |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 633 | /* Check for the override clocksource. */ |
| 634 | list_for_each_entry(cs, &clocksource_list, list) { |
Thomas Gleixner | f5a2e34 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 635 | if (skipcur && cs == curr_clocksource) |
| 636 | continue; |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 637 | if (strcmp(cs->name, override_name) != 0) |
| 638 | continue; |
| 639 | /* |
| 640 | * Check to make sure we don't switch to a non-highres |
| 641 | * capable clocksource if the tick code is in oneshot |
| 642 | * mode (highres or nohz) |
| 643 | */ |
Thomas Gleixner | 5d33b88 | 2013-04-25 20:31:43 +0000 | [diff] [blame] | 644 | if (!(cs->flags & CLOCK_SOURCE_VALID_FOR_HRES) && oneshot) { |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 645 | /* Override clocksource cannot be used. */ |
| 646 | printk(KERN_WARNING "Override clocksource %s is not " |
| 647 | "HRT compatible. Cannot switch while in " |
| 648 | "HRT/NOHZ mode\n", cs->name); |
| 649 | override_name[0] = 0; |
| 650 | } else |
| 651 | /* Override clocksource can be used. */ |
| 652 | best = cs; |
| 653 | break; |
| 654 | } |
Thomas Gleixner | ba919d1 | 2013-04-25 20:31:44 +0000 | [diff] [blame] | 655 | |
| 656 | if (curr_clocksource != best && !timekeeping_notify(best)) { |
| 657 | pr_info("Switched to clocksource %s\n", best->name); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 658 | curr_clocksource = best; |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 659 | } |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 660 | } |
| 661 | |
Thomas Gleixner | f5a2e34 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 662 | /** |
| 663 | * clocksource_select - Select the best clocksource available |
| 664 | * |
| 665 | * Private function. Must hold clocksource_mutex when called. |
| 666 | * |
| 667 | * Select the clocksource with the best rating, or the clocksource, |
| 668 | * which is selected by userspace override. |
| 669 | */ |
| 670 | static void clocksource_select(void) |
| 671 | { |
| 672 | return __clocksource_select(false); |
| 673 | } |
| 674 | |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 675 | static void clocksource_select_fallback(void) |
| 676 | { |
| 677 | return __clocksource_select(true); |
| 678 | } |
| 679 | |
John Stultz | 592913e | 2010-07-13 17:56:20 -0700 | [diff] [blame] | 680 | #else /* !CONFIG_ARCH_USES_GETTIMEOFFSET */ |
Thomas Gleixner | 54a6bc0 | 2009-09-14 19:49:02 +0200 | [diff] [blame] | 681 | |
| 682 | static inline void clocksource_select(void) { } |
Thomas Gleixner | 1eaff67 | 2013-05-28 09:48:46 +0200 | [diff] [blame] | 683 | static inline void clocksource_select_fallback(void) { } |
Thomas Gleixner | 54a6bc0 | 2009-09-14 19:49:02 +0200 | [diff] [blame] | 684 | |
| 685 | #endif |
| 686 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 687 | /* |
| 688 | * clocksource_done_booting - Called near the end of core bootup |
| 689 | * |
| 690 | * Hack to avoid lots of clocksource churn at boot time. |
| 691 | * We use fs_initcall because we want this to start before |
| 692 | * device_initcall but after subsys_initcall. |
| 693 | */ |
| 694 | static int __init clocksource_done_booting(void) |
| 695 | { |
john stultz | ad6759f | 2010-03-01 12:34:43 -0800 | [diff] [blame] | 696 | mutex_lock(&clocksource_mutex); |
| 697 | curr_clocksource = clocksource_default_clock(); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 698 | finished_booting = 1; |
Thomas Gleixner | 54a6bc0 | 2009-09-14 19:49:02 +0200 | [diff] [blame] | 699 | /* |
| 700 | * Run the watchdog first to eliminate unstable clock sources |
| 701 | */ |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 702 | __clocksource_watchdog_kthread(); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 703 | clocksource_select(); |
Thomas Gleixner | e6c7330 | 2009-09-14 19:51:11 +0200 | [diff] [blame] | 704 | mutex_unlock(&clocksource_mutex); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 705 | return 0; |
| 706 | } |
| 707 | fs_initcall(clocksource_done_booting); |
| 708 | |
Thomas Gleixner | 92c7e00 | 2007-02-16 01:27:33 -0800 | [diff] [blame] | 709 | /* |
| 710 | * Enqueue the clocksource sorted by rating |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 711 | */ |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 712 | static void clocksource_enqueue(struct clocksource *cs) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 713 | { |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 714 | struct list_head *entry = &clocksource_list; |
| 715 | struct clocksource *tmp; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 716 | |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 717 | list_for_each_entry(tmp, &clocksource_list, list) |
Thomas Gleixner | 92c7e00 | 2007-02-16 01:27:33 -0800 | [diff] [blame] | 718 | /* Keep track of the place, where to insert */ |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 719 | if (tmp->rating >= cs->rating) |
| 720 | entry = &tmp->list; |
| 721 | list_add(&cs->list, entry); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 722 | } |
| 723 | |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 724 | /** |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 725 | * __clocksource_updatefreq_scale - Used update clocksource with new freq |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 726 | * @cs: clocksource to be registered |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 727 | * @scale: Scale factor multiplied against freq to get clocksource hz |
| 728 | * @freq: clocksource frequency (cycles per second) divided by scale |
| 729 | * |
| 730 | * This should only be called from the clocksource->enable() method. |
| 731 | * |
| 732 | * This *SHOULD NOT* be called directly! Please use the |
| 733 | * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions. |
| 734 | */ |
| 735 | void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq) |
| 736 | { |
Thomas Gleixner | c0e299b | 2011-05-20 10:50:52 +0200 | [diff] [blame] | 737 | u64 sec; |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 738 | /* |
Thomas Gleixner | 724ed53 | 2011-05-18 21:33:40 +0000 | [diff] [blame] | 739 | * Calc the maximum number of seconds which we can run before |
| 740 | * wrapping around. For clocksources which have a mask > 32bit |
| 741 | * we need to limit the max sleep time to have a good |
| 742 | * conversion precision. 10 minutes is still a reasonable |
| 743 | * amount. That results in a shift value of 24 for a |
| 744 | * clocksource with mask >= 40bit and f >= 4GHz. That maps to |
| 745 | * ~ 0.06ppm granularity for NTP. We apply the same 12.5% |
| 746 | * margin as we do in clocksource_max_deferment() |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 747 | */ |
Yang Honggang (Joseph) | b1f9196 | 2011-12-01 22:22:41 -0500 | [diff] [blame] | 748 | sec = (cs->mask - (cs->mask >> 3)); |
Thomas Gleixner | 724ed53 | 2011-05-18 21:33:40 +0000 | [diff] [blame] | 749 | do_div(sec, freq); |
| 750 | do_div(sec, scale); |
| 751 | if (!sec) |
| 752 | sec = 1; |
| 753 | else if (sec > 600 && cs->mask > UINT_MAX) |
| 754 | sec = 600; |
| 755 | |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 756 | clocks_calc_mult_shift(&cs->mult, &cs->shift, freq, |
Thomas Gleixner | 724ed53 | 2011-05-18 21:33:40 +0000 | [diff] [blame] | 757 | NSEC_PER_SEC / scale, sec * scale); |
John Stultz | d65670a | 2011-10-31 17:06:35 -0400 | [diff] [blame] | 758 | |
| 759 | /* |
| 760 | * for clocksources that have large mults, to avoid overflow. |
| 761 | * Since mult may be adjusted by ntp, add an safety extra margin |
| 762 | * |
| 763 | */ |
| 764 | cs->maxadj = clocksource_max_adjustment(cs); |
| 765 | while ((cs->mult + cs->maxadj < cs->mult) |
| 766 | || (cs->mult - cs->maxadj > cs->mult)) { |
| 767 | cs->mult >>= 1; |
| 768 | cs->shift--; |
| 769 | cs->maxadj = clocksource_max_adjustment(cs); |
| 770 | } |
| 771 | |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 772 | cs->max_idle_ns = clocksource_max_deferment(cs); |
| 773 | } |
| 774 | EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale); |
| 775 | |
| 776 | /** |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 777 | * __clocksource_register_scale - Used to install new clocksources |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 778 | * @cs: clocksource to be registered |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 779 | * @scale: Scale factor multiplied against freq to get clocksource hz |
| 780 | * @freq: clocksource frequency (cycles per second) divided by scale |
| 781 | * |
| 782 | * Returns -EBUSY if registration fails, zero otherwise. |
| 783 | * |
| 784 | * This *SHOULD NOT* be called directly! Please use the |
| 785 | * clocksource_register_hz() or clocksource_register_khz helper functions. |
| 786 | */ |
| 787 | int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq) |
| 788 | { |
| 789 | |
Uwe Kleine-König | b595076 | 2010-11-01 15:38:34 -0400 | [diff] [blame] | 790 | /* Initialize mult/shift and max_idle_ns */ |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 791 | __clocksource_updatefreq_scale(cs, scale, freq); |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 792 | |
John Stultz | 852db46 | 2010-07-13 17:56:28 -0700 | [diff] [blame] | 793 | /* Add clocksource to the clcoksource list */ |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 794 | mutex_lock(&clocksource_mutex); |
| 795 | clocksource_enqueue(cs); |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 796 | clocksource_enqueue_watchdog(cs); |
john stultz | e05b2ef | 2011-05-04 18:16:50 -0700 | [diff] [blame] | 797 | clocksource_select(); |
John Stultz | d7e81c2 | 2010-05-07 18:07:38 -0700 | [diff] [blame] | 798 | mutex_unlock(&clocksource_mutex); |
| 799 | return 0; |
| 800 | } |
| 801 | EXPORT_SYMBOL_GPL(__clocksource_register_scale); |
| 802 | |
| 803 | |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 804 | /** |
john stultz | a275254 | 2006-06-26 00:25:14 -0700 | [diff] [blame] | 805 | * clocksource_register - Used to install new clocksources |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 806 | * @cs: clocksource to be registered |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 807 | * |
| 808 | * Returns -EBUSY if registration fails, zero otherwise. |
| 809 | */ |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 810 | int clocksource_register(struct clocksource *cs) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 811 | { |
John Stultz | d65670a | 2011-10-31 17:06:35 -0400 | [diff] [blame] | 812 | /* calculate max adjustment for given mult/shift */ |
| 813 | cs->maxadj = clocksource_max_adjustment(cs); |
| 814 | WARN_ONCE(cs->mult + cs->maxadj < cs->mult, |
| 815 | "Clocksource %s might overflow on 11%% adjustment\n", |
| 816 | cs->name); |
| 817 | |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 818 | /* calculate max idle time permitted for this clocksource */ |
| 819 | cs->max_idle_ns = clocksource_max_deferment(cs); |
| 820 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 821 | mutex_lock(&clocksource_mutex); |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 822 | clocksource_enqueue(cs); |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 823 | clocksource_enqueue_watchdog(cs); |
john stultz | e05b2ef | 2011-05-04 18:16:50 -0700 | [diff] [blame] | 824 | clocksource_select(); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 825 | mutex_unlock(&clocksource_mutex); |
Martin Schwidefsky | f1b8274 | 2009-08-14 15:47:21 +0200 | [diff] [blame] | 826 | return 0; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 827 | } |
john stultz | a275254 | 2006-06-26 00:25:14 -0700 | [diff] [blame] | 828 | EXPORT_SYMBOL(clocksource_register); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 829 | |
Thomas Gleixner | d0981a1 | 2009-08-19 11:26:09 +0200 | [diff] [blame] | 830 | static void __clocksource_change_rating(struct clocksource *cs, int rating) |
| 831 | { |
| 832 | list_del(&cs->list); |
| 833 | cs->rating = rating; |
| 834 | clocksource_enqueue(cs); |
Thomas Gleixner | d0981a1 | 2009-08-19 11:26:09 +0200 | [diff] [blame] | 835 | } |
| 836 | |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 837 | /** |
Thomas Gleixner | 92c7e00 | 2007-02-16 01:27:33 -0800 | [diff] [blame] | 838 | * clocksource_change_rating - Change the rating of a registered clocksource |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 839 | * @cs: clocksource to be changed |
| 840 | * @rating: new rating |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 841 | */ |
Thomas Gleixner | 92c7e00 | 2007-02-16 01:27:33 -0800 | [diff] [blame] | 842 | void clocksource_change_rating(struct clocksource *cs, int rating) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 843 | { |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 844 | mutex_lock(&clocksource_mutex); |
Thomas Gleixner | d0981a1 | 2009-08-19 11:26:09 +0200 | [diff] [blame] | 845 | __clocksource_change_rating(cs, rating); |
Thomas Gleixner | 332962f | 2013-07-04 22:46:45 +0200 | [diff] [blame] | 846 | clocksource_select(); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 847 | mutex_unlock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 848 | } |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 849 | EXPORT_SYMBOL(clocksource_change_rating); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 850 | |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 851 | /* |
| 852 | * Unbind clocksource @cs. Called with clocksource_mutex held |
| 853 | */ |
| 854 | static int clocksource_unbind(struct clocksource *cs) |
| 855 | { |
| 856 | /* |
| 857 | * I really can't convince myself to support this on hardware |
| 858 | * designed by lobotomized monkeys. |
| 859 | */ |
| 860 | if (clocksource_is_watchdog(cs)) |
| 861 | return -EBUSY; |
| 862 | |
| 863 | if (cs == curr_clocksource) { |
| 864 | /* Select and try to install a replacement clock source */ |
| 865 | clocksource_select_fallback(); |
| 866 | if (curr_clocksource == cs) |
| 867 | return -EBUSY; |
| 868 | } |
| 869 | clocksource_dequeue_watchdog(cs); |
| 870 | list_del_init(&cs->list); |
| 871 | return 0; |
| 872 | } |
| 873 | |
Thomas Gleixner | 4713e22c | 2008-01-30 13:30:02 +0100 | [diff] [blame] | 874 | /** |
| 875 | * clocksource_unregister - remove a registered clocksource |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 876 | * @cs: clocksource to be unregistered |
Thomas Gleixner | 4713e22c | 2008-01-30 13:30:02 +0100 | [diff] [blame] | 877 | */ |
Thomas Gleixner | a89c7ed | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 878 | int clocksource_unregister(struct clocksource *cs) |
Thomas Gleixner | 4713e22c | 2008-01-30 13:30:02 +0100 | [diff] [blame] | 879 | { |
Thomas Gleixner | a89c7ed | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 880 | int ret = 0; |
| 881 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 882 | mutex_lock(&clocksource_mutex); |
Thomas Gleixner | a89c7ed | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 883 | if (!list_empty(&cs->list)) |
| 884 | ret = clocksource_unbind(cs); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 885 | mutex_unlock(&clocksource_mutex); |
Thomas Gleixner | a89c7ed | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 886 | return ret; |
Thomas Gleixner | 4713e22c | 2008-01-30 13:30:02 +0100 | [diff] [blame] | 887 | } |
Martin Schwidefsky | fb63a0e | 2009-08-14 15:47:24 +0200 | [diff] [blame] | 888 | EXPORT_SYMBOL(clocksource_unregister); |
Thomas Gleixner | 4713e22c | 2008-01-30 13:30:02 +0100 | [diff] [blame] | 889 | |
Daniel Walker | 2b01370 | 2006-12-10 02:21:30 -0800 | [diff] [blame] | 890 | #ifdef CONFIG_SYSFS |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 891 | /** |
| 892 | * sysfs_show_current_clocksources - sysfs interface for current clocksource |
| 893 | * @dev: unused |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 894 | * @attr: unused |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 895 | * @buf: char buffer to be filled with clocksource list |
| 896 | * |
| 897 | * Provides sysfs interface for listing current clocksource. |
| 898 | */ |
| 899 | static ssize_t |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 900 | sysfs_show_current_clocksources(struct device *dev, |
| 901 | struct device_attribute *attr, char *buf) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 902 | { |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 903 | ssize_t count = 0; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 904 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 905 | mutex_lock(&clocksource_mutex); |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 906 | count = snprintf(buf, PAGE_SIZE, "%s\n", curr_clocksource->name); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 907 | mutex_unlock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 908 | |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 909 | return count; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 910 | } |
| 911 | |
Patrick Palka | 891292a | 2013-10-11 13:11:55 -0400 | [diff] [blame] | 912 | ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt) |
Thomas Gleixner | 29b54078 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 913 | { |
| 914 | size_t ret = cnt; |
| 915 | |
| 916 | /* strings from sysfs write are not 0 terminated! */ |
| 917 | if (!cnt || cnt >= CS_NAME_LEN) |
| 918 | return -EINVAL; |
| 919 | |
| 920 | /* strip of \n: */ |
| 921 | if (buf[cnt-1] == '\n') |
| 922 | cnt--; |
| 923 | if (cnt > 0) |
| 924 | memcpy(dst, buf, cnt); |
| 925 | dst[cnt] = 0; |
| 926 | return ret; |
| 927 | } |
| 928 | |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 929 | /** |
| 930 | * sysfs_override_clocksource - interface for manually overriding clocksource |
| 931 | * @dev: unused |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 932 | * @attr: unused |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 933 | * @buf: name of override clocksource |
| 934 | * @count: length of buffer |
| 935 | * |
| 936 | * Takes input from sysfs interface for manually overriding the default |
Uwe Kleine-König | b71a8eb | 2009-10-06 12:42:51 +0200 | [diff] [blame] | 937 | * clocksource selection. |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 938 | */ |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 939 | static ssize_t sysfs_override_clocksource(struct device *dev, |
| 940 | struct device_attribute *attr, |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 941 | const char *buf, size_t count) |
| 942 | { |
Elad Wexler | 233bcb4 | 2013-09-12 13:28:54 +0300 | [diff] [blame] | 943 | ssize_t ret; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 944 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 945 | mutex_lock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 946 | |
Thomas Gleixner | 03e13cf | 2013-04-25 20:31:50 +0000 | [diff] [blame] | 947 | ret = sysfs_get_uname(buf, override_name, count); |
Thomas Gleixner | 29b54078 | 2013-04-25 20:31:45 +0000 | [diff] [blame] | 948 | if (ret >= 0) |
| 949 | clocksource_select(); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 950 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 951 | mutex_unlock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 952 | |
| 953 | return ret; |
| 954 | } |
| 955 | |
| 956 | /** |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 957 | * sysfs_unbind_current_clocksource - interface for manually unbinding clocksource |
| 958 | * @dev: unused |
| 959 | * @attr: unused |
| 960 | * @buf: unused |
| 961 | * @count: length of buffer |
| 962 | * |
| 963 | * Takes input from sysfs interface for manually unbinding a clocksource. |
| 964 | */ |
| 965 | static ssize_t sysfs_unbind_clocksource(struct device *dev, |
| 966 | struct device_attribute *attr, |
| 967 | const char *buf, size_t count) |
| 968 | { |
| 969 | struct clocksource *cs; |
| 970 | char name[CS_NAME_LEN]; |
Elad Wexler | 233bcb4 | 2013-09-12 13:28:54 +0300 | [diff] [blame] | 971 | ssize_t ret; |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 972 | |
Thomas Gleixner | 03e13cf | 2013-04-25 20:31:50 +0000 | [diff] [blame] | 973 | ret = sysfs_get_uname(buf, name, count); |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 974 | if (ret < 0) |
| 975 | return ret; |
| 976 | |
| 977 | ret = -ENODEV; |
| 978 | mutex_lock(&clocksource_mutex); |
| 979 | list_for_each_entry(cs, &clocksource_list, list) { |
| 980 | if (strcmp(cs->name, name)) |
| 981 | continue; |
| 982 | ret = clocksource_unbind(cs); |
| 983 | break; |
| 984 | } |
| 985 | mutex_unlock(&clocksource_mutex); |
| 986 | |
| 987 | return ret ? ret : count; |
| 988 | } |
| 989 | |
| 990 | /** |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 991 | * sysfs_show_available_clocksources - sysfs interface for listing clocksource |
| 992 | * @dev: unused |
Kusanagi Kouichi | b1b73d0 | 2011-12-19 18:13:19 +0900 | [diff] [blame] | 993 | * @attr: unused |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 994 | * @buf: char buffer to be filled with clocksource list |
| 995 | * |
| 996 | * Provides sysfs interface for listing registered clocksources |
| 997 | */ |
| 998 | static ssize_t |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 999 | sysfs_show_available_clocksources(struct device *dev, |
| 1000 | struct device_attribute *attr, |
Andi Kleen | 4a0b2b4 | 2008-07-01 18:48:41 +0200 | [diff] [blame] | 1001 | char *buf) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1002 | { |
Matthias Kaehlcke | 2e19758 | 2007-10-18 23:39:58 -0700 | [diff] [blame] | 1003 | struct clocksource *src; |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 1004 | ssize_t count = 0; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1005 | |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 1006 | mutex_lock(&clocksource_mutex); |
Matthias Kaehlcke | 2e19758 | 2007-10-18 23:39:58 -0700 | [diff] [blame] | 1007 | list_for_each_entry(src, &clocksource_list, list) { |
Thomas Gleixner | cd6d95d | 2009-06-12 11:29:27 +0200 | [diff] [blame] | 1008 | /* |
| 1009 | * Don't show non-HRES clocksource if the tick code is |
| 1010 | * in one shot mode (highres=on or nohz=on) |
| 1011 | */ |
| 1012 | if (!tick_oneshot_mode_active() || |
| 1013 | (src->flags & CLOCK_SOURCE_VALID_FOR_HRES)) |
john stultz | 3f68535 | 2009-01-21 22:53:22 -0700 | [diff] [blame] | 1014 | count += snprintf(buf + count, |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 1015 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), |
| 1016 | "%s ", src->name); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1017 | } |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 1018 | mutex_unlock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1019 | |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 1020 | count += snprintf(buf + count, |
| 1021 | max((ssize_t)PAGE_SIZE - count, (ssize_t)0), "\n"); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1022 | |
Miao Xie | 5e2cb10 | 2008-02-06 01:36:53 -0800 | [diff] [blame] | 1023 | return count; |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1024 | } |
| 1025 | |
| 1026 | /* |
| 1027 | * Sysfs setup bits: |
| 1028 | */ |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1029 | static DEVICE_ATTR(current_clocksource, 0644, sysfs_show_current_clocksources, |
Daniel Walker | f5f1a24 | 2006-12-10 02:21:33 -0800 | [diff] [blame] | 1030 | sysfs_override_clocksource); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1031 | |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 1032 | static DEVICE_ATTR(unbind_clocksource, 0200, NULL, sysfs_unbind_clocksource); |
| 1033 | |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1034 | static DEVICE_ATTR(available_clocksource, 0444, |
Daniel Walker | f5f1a24 | 2006-12-10 02:21:33 -0800 | [diff] [blame] | 1035 | sysfs_show_available_clocksources, NULL); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1036 | |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1037 | static struct bus_type clocksource_subsys = { |
Kay Sievers | af5ca3f4 | 2007-12-20 02:09:39 +0100 | [diff] [blame] | 1038 | .name = "clocksource", |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1039 | .dev_name = "clocksource", |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1040 | }; |
| 1041 | |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1042 | static struct device device_clocksource = { |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1043 | .id = 0, |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1044 | .bus = &clocksource_subsys, |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1045 | }; |
| 1046 | |
john stultz | ad59617 | 2006-06-26 00:25:06 -0700 | [diff] [blame] | 1047 | static int __init init_clocksource_sysfs(void) |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1048 | { |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1049 | int error = subsys_system_register(&clocksource_subsys, NULL); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1050 | |
| 1051 | if (!error) |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1052 | error = device_register(&device_clocksource); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1053 | if (!error) |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1054 | error = device_create_file( |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1055 | &device_clocksource, |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1056 | &dev_attr_current_clocksource); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1057 | if (!error) |
Thomas Gleixner | 7eaeb34 | 2013-04-25 20:31:46 +0000 | [diff] [blame] | 1058 | error = device_create_file(&device_clocksource, |
| 1059 | &dev_attr_unbind_clocksource); |
| 1060 | if (!error) |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1061 | error = device_create_file( |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1062 | &device_clocksource, |
Kay Sievers | d369a5d | 2011-12-14 15:28:51 -0800 | [diff] [blame] | 1063 | &dev_attr_available_clocksource); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1064 | return error; |
| 1065 | } |
| 1066 | |
| 1067 | device_initcall(init_clocksource_sysfs); |
Daniel Walker | 2b01370 | 2006-12-10 02:21:30 -0800 | [diff] [blame] | 1068 | #endif /* CONFIG_SYSFS */ |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1069 | |
| 1070 | /** |
| 1071 | * boot_override_clocksource - boot clock override |
| 1072 | * @str: override name |
| 1073 | * |
| 1074 | * Takes a clocksource= boot argument and uses it |
| 1075 | * as the clocksource override name. |
| 1076 | */ |
| 1077 | static int __init boot_override_clocksource(char* str) |
| 1078 | { |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 1079 | mutex_lock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1080 | if (str) |
| 1081 | strlcpy(override_name, str, sizeof(override_name)); |
Martin Schwidefsky | 75c5158 | 2009-08-14 15:47:30 +0200 | [diff] [blame] | 1082 | mutex_unlock(&clocksource_mutex); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1083 | return 1; |
| 1084 | } |
| 1085 | |
| 1086 | __setup("clocksource=", boot_override_clocksource); |
| 1087 | |
| 1088 | /** |
| 1089 | * boot_override_clock - Compatibility layer for deprecated boot option |
| 1090 | * @str: override name |
| 1091 | * |
| 1092 | * DEPRECATED! Takes a clock= boot argument and uses it |
| 1093 | * as the clocksource override name |
| 1094 | */ |
| 1095 | static int __init boot_override_clock(char* str) |
| 1096 | { |
john stultz | 5d0cf41 | 2006-06-26 00:25:12 -0700 | [diff] [blame] | 1097 | if (!strcmp(str, "pmtmr")) { |
| 1098 | printk("Warning: clock=pmtmr is deprecated. " |
| 1099 | "Use clocksource=acpi_pm.\n"); |
| 1100 | return boot_override_clocksource("acpi_pm"); |
| 1101 | } |
| 1102 | printk("Warning! clock= boot option is deprecated. " |
| 1103 | "Use clocksource=xyz\n"); |
john stultz | 734efb4 | 2006-06-26 00:25:05 -0700 | [diff] [blame] | 1104 | return boot_override_clocksource(str); |
| 1105 | } |
| 1106 | |
| 1107 | __setup("clock=", boot_override_clock); |