Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/time/tick-common.c |
| 3 | * |
| 4 | * This file contains the base functions to manage periodic tick |
| 5 | * related events. |
| 6 | * |
| 7 | * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> |
| 8 | * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar |
| 9 | * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner |
| 10 | * |
| 11 | * This code is licenced under the GPL version 2. For details see |
| 12 | * kernel-base/COPYING. |
| 13 | */ |
| 14 | #include <linux/cpu.h> |
| 15 | #include <linux/err.h> |
| 16 | #include <linux/hrtimer.h> |
| 17 | #include <linux/irq.h> |
| 18 | #include <linux/percpu.h> |
| 19 | #include <linux/profile.h> |
| 20 | #include <linux/sched.h> |
| 21 | #include <linux/tick.h> |
| 22 | |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 23 | #include "tick-internal.h" |
| 24 | |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 25 | /* |
| 26 | * Tick devices |
| 27 | */ |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 28 | DEFINE_PER_CPU(struct tick_device, tick_cpu_device); |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 29 | /* |
| 30 | * Tick next event: keeps track of the tick time |
| 31 | */ |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 32 | ktime_t tick_next_period; |
| 33 | ktime_t tick_period; |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 34 | static int tick_do_timer_cpu = -1; |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 35 | DEFINE_SPINLOCK(tick_device_lock); |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 36 | |
| 37 | /* |
| 38 | * Periodic tick |
| 39 | */ |
| 40 | static void tick_periodic(int cpu) |
| 41 | { |
| 42 | if (tick_do_timer_cpu == cpu) { |
| 43 | write_seqlock(&xtime_lock); |
| 44 | |
| 45 | /* Keep track of the next tick event */ |
| 46 | tick_next_period = ktime_add(tick_next_period, tick_period); |
| 47 | |
| 48 | do_timer(1); |
| 49 | write_sequnlock(&xtime_lock); |
| 50 | } |
| 51 | |
| 52 | update_process_times(user_mode(get_irq_regs())); |
| 53 | profile_tick(CPU_PROFILING); |
| 54 | } |
| 55 | |
| 56 | /* |
| 57 | * Event handler for periodic ticks |
| 58 | */ |
| 59 | void tick_handle_periodic(struct clock_event_device *dev) |
| 60 | { |
| 61 | int cpu = smp_processor_id(); |
| 62 | |
| 63 | tick_periodic(cpu); |
| 64 | |
| 65 | if (dev->mode != CLOCK_EVT_MODE_ONESHOT) |
| 66 | return; |
| 67 | /* |
| 68 | * Setup the next period for devices, which do not have |
| 69 | * periodic mode: |
| 70 | */ |
| 71 | for (;;) { |
| 72 | ktime_t next = ktime_add(dev->next_event, tick_period); |
| 73 | |
| 74 | if (!clockevents_program_event(dev, next, ktime_get())) |
| 75 | return; |
| 76 | tick_periodic(cpu); |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * Setup the device for a periodic tick |
| 82 | */ |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 83 | void tick_setup_periodic(struct clock_event_device *dev, int broadcast) |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 84 | { |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 85 | tick_set_periodic_handler(dev, broadcast); |
| 86 | |
| 87 | /* Broadcast setup ? */ |
| 88 | if (!tick_device_is_functional(dev)) |
| 89 | return; |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 90 | |
| 91 | if (dev->features & CLOCK_EVT_FEAT_PERIODIC) { |
| 92 | clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC); |
| 93 | } else { |
| 94 | unsigned long seq; |
| 95 | ktime_t next; |
| 96 | |
| 97 | do { |
| 98 | seq = read_seqbegin(&xtime_lock); |
| 99 | next = tick_next_period; |
| 100 | } while (read_seqretry(&xtime_lock, seq)); |
| 101 | |
| 102 | clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT); |
| 103 | |
| 104 | for (;;) { |
| 105 | if (!clockevents_program_event(dev, next, ktime_get())) |
| 106 | return; |
| 107 | next = ktime_add(next, tick_period); |
| 108 | } |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * Setup the tick device |
| 114 | */ |
| 115 | static void tick_setup_device(struct tick_device *td, |
| 116 | struct clock_event_device *newdev, int cpu, |
| 117 | cpumask_t cpumask) |
| 118 | { |
| 119 | ktime_t next_event; |
| 120 | void (*handler)(struct clock_event_device *) = NULL; |
| 121 | |
| 122 | /* |
| 123 | * First device setup ? |
| 124 | */ |
| 125 | if (!td->evtdev) { |
| 126 | /* |
| 127 | * If no cpu took the do_timer update, assign it to |
| 128 | * this cpu: |
| 129 | */ |
| 130 | if (tick_do_timer_cpu == -1) { |
| 131 | tick_do_timer_cpu = cpu; |
| 132 | tick_next_period = ktime_get(); |
| 133 | tick_period = ktime_set(0, NSEC_PER_SEC / HZ); |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * Startup in periodic mode first. |
| 138 | */ |
| 139 | td->mode = TICKDEV_MODE_PERIODIC; |
| 140 | } else { |
| 141 | handler = td->evtdev->event_handler; |
| 142 | next_event = td->evtdev->next_event; |
| 143 | } |
| 144 | |
| 145 | td->evtdev = newdev; |
| 146 | |
| 147 | /* |
| 148 | * When the device is not per cpu, pin the interrupt to the |
| 149 | * current cpu: |
| 150 | */ |
| 151 | if (!cpus_equal(newdev->cpumask, cpumask)) |
| 152 | irq_set_affinity(newdev->irq, cpumask); |
| 153 | |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 154 | /* |
| 155 | * When global broadcasting is active, check if the current |
| 156 | * device is registered as a placeholder for broadcast mode. |
| 157 | * This allows us to handle this x86 misfeature in a generic |
| 158 | * way. |
| 159 | */ |
| 160 | if (tick_device_uses_broadcast(newdev, cpu)) |
| 161 | return; |
| 162 | |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 163 | if (td->mode == TICKDEV_MODE_PERIODIC) |
| 164 | tick_setup_periodic(newdev, 0); |
| 165 | } |
| 166 | |
| 167 | /* |
| 168 | * Check, if the new registered device should be used. |
| 169 | */ |
| 170 | static int tick_check_new_device(struct clock_event_device *newdev) |
| 171 | { |
| 172 | struct clock_event_device *curdev; |
| 173 | struct tick_device *td; |
| 174 | int cpu, ret = NOTIFY_OK; |
| 175 | unsigned long flags; |
| 176 | cpumask_t cpumask; |
| 177 | |
| 178 | spin_lock_irqsave(&tick_device_lock, flags); |
| 179 | |
| 180 | cpu = smp_processor_id(); |
| 181 | if (!cpu_isset(cpu, newdev->cpumask)) |
| 182 | goto out; |
| 183 | |
| 184 | td = &per_cpu(tick_cpu_device, cpu); |
| 185 | curdev = td->evtdev; |
| 186 | cpumask = cpumask_of_cpu(cpu); |
| 187 | |
| 188 | /* cpu local device ? */ |
| 189 | if (!cpus_equal(newdev->cpumask, cpumask)) { |
| 190 | |
| 191 | /* |
| 192 | * If the cpu affinity of the device interrupt can not |
| 193 | * be set, ignore it. |
| 194 | */ |
| 195 | if (!irq_can_set_affinity(newdev->irq)) |
| 196 | goto out_bc; |
| 197 | |
| 198 | /* |
| 199 | * If we have a cpu local device already, do not replace it |
| 200 | * by a non cpu local device |
| 201 | */ |
| 202 | if (curdev && cpus_equal(curdev->cpumask, cpumask)) |
| 203 | goto out_bc; |
| 204 | } |
| 205 | |
| 206 | /* |
| 207 | * If we have an active device, then check the rating and the oneshot |
| 208 | * feature. |
| 209 | */ |
| 210 | if (curdev) { |
| 211 | /* |
| 212 | * Check the rating |
| 213 | */ |
| 214 | if (curdev->rating >= newdev->rating) |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 215 | goto out_bc; |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 216 | } |
| 217 | |
| 218 | /* |
| 219 | * Replace the eventually existing device by the new |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 220 | * device. If the current device is the broadcast device, do |
| 221 | * not give it back to the clockevents layer ! |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 222 | */ |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 223 | if (tick_is_broadcast_device(curdev)) { |
| 224 | clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN); |
| 225 | curdev = NULL; |
| 226 | } |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 227 | clockevents_exchange_device(curdev, newdev); |
| 228 | tick_setup_device(td, newdev, cpu, cpumask); |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 229 | |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 230 | spin_unlock_irqrestore(&tick_device_lock, flags); |
| 231 | return NOTIFY_STOP; |
| 232 | |
| 233 | out_bc: |
| 234 | /* |
| 235 | * Can the new device be used as a broadcast device ? |
| 236 | */ |
| 237 | if (tick_check_broadcast_device(newdev)) |
| 238 | ret = NOTIFY_STOP; |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 239 | out: |
| 240 | spin_unlock_irqrestore(&tick_device_lock, flags); |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 241 | |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 242 | return ret; |
| 243 | } |
| 244 | |
| 245 | /* |
| 246 | * Shutdown an event device on a given cpu: |
| 247 | * |
| 248 | * This is called on a life CPU, when a CPU is dead. So we cannot |
| 249 | * access the hardware device itself. |
| 250 | * We just set the mode and remove it from the lists. |
| 251 | */ |
| 252 | static void tick_shutdown(unsigned int *cpup) |
| 253 | { |
| 254 | struct tick_device *td = &per_cpu(tick_cpu_device, *cpup); |
| 255 | struct clock_event_device *dev = td->evtdev; |
| 256 | unsigned long flags; |
| 257 | |
| 258 | spin_lock_irqsave(&tick_device_lock, flags); |
| 259 | td->mode = TICKDEV_MODE_PERIODIC; |
| 260 | if (dev) { |
| 261 | /* |
| 262 | * Prevent that the clock events layer tries to call |
| 263 | * the set mode function! |
| 264 | */ |
| 265 | dev->mode = CLOCK_EVT_MODE_UNUSED; |
| 266 | clockevents_exchange_device(dev, NULL); |
| 267 | td->evtdev = NULL; |
| 268 | } |
| 269 | spin_unlock_irqrestore(&tick_device_lock, flags); |
| 270 | } |
| 271 | |
| 272 | /* |
| 273 | * Notification about clock event devices |
| 274 | */ |
| 275 | static int tick_notify(struct notifier_block *nb, unsigned long reason, |
| 276 | void *dev) |
| 277 | { |
| 278 | switch (reason) { |
| 279 | |
| 280 | case CLOCK_EVT_NOTIFY_ADD: |
| 281 | return tick_check_new_device(dev); |
| 282 | |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 283 | case CLOCK_EVT_NOTIFY_BROADCAST_ON: |
| 284 | case CLOCK_EVT_NOTIFY_BROADCAST_OFF: |
| 285 | tick_broadcast_on_off(reason, dev); |
| 286 | break; |
| 287 | |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 288 | case CLOCK_EVT_NOTIFY_CPU_DEAD: |
Thomas Gleixner | f8381cb | 2007-02-16 01:28:02 -0800 | [diff] [blame^] | 289 | tick_shutdown_broadcast(dev); |
Thomas Gleixner | 906568c | 2007-02-16 01:28:01 -0800 | [diff] [blame] | 290 | tick_shutdown(dev); |
| 291 | break; |
| 292 | |
| 293 | default: |
| 294 | break; |
| 295 | } |
| 296 | |
| 297 | return NOTIFY_OK; |
| 298 | } |
| 299 | |
| 300 | static struct notifier_block tick_notifier = { |
| 301 | .notifier_call = tick_notify, |
| 302 | }; |
| 303 | |
| 304 | /** |
| 305 | * tick_init - initialize the tick control |
| 306 | * |
| 307 | * Register the notifier with the clockevents framework |
| 308 | */ |
| 309 | void __init tick_init(void) |
| 310 | { |
| 311 | clockevents_register_notifier(&tick_notifier); |
| 312 | } |