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diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
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1/*
2 * linux/kernel/time/tick-broadcast.c
3 *
4 * This file contains functions which emulate a local clock-event
5 * device via a broadcast event source.
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
23#include "tick-internal.h"
24
25/*
26 * Broadcast support for broken x86 hardware, where the local apic
27 * timer stops in C3 state.
28 */
29
30struct tick_device tick_broadcast_device;
31static cpumask_t tick_broadcast_mask;
32static DEFINE_SPINLOCK(tick_broadcast_lock);
33
34/*
35 * Debugging: see timer_list.c
36 */
37struct tick_device *tick_get_broadcast_device(void)
38{
39 return &tick_broadcast_device;
40}
41
42cpumask_t *tick_get_broadcast_mask(void)
43{
44 return &tick_broadcast_mask;
45}
46
47/*
48 * Start the device in periodic mode
49 */
50static void tick_broadcast_start_periodic(struct clock_event_device *bc)
51{
52 if (bc && bc->mode == CLOCK_EVT_MODE_SHUTDOWN)
53 tick_setup_periodic(bc, 1);
54}
55
56/*
57 * Check, if the device can be utilized as broadcast device:
58 */
59int tick_check_broadcast_device(struct clock_event_device *dev)
60{
61 if (tick_broadcast_device.evtdev ||
62 (dev->features & CLOCK_EVT_FEAT_C3STOP))
63 return 0;
64
65 clockevents_exchange_device(NULL, dev);
66 tick_broadcast_device.evtdev = dev;
67 if (!cpus_empty(tick_broadcast_mask))
68 tick_broadcast_start_periodic(dev);
69 return 1;
70}
71
72/*
73 * Check, if the device is the broadcast device
74 */
75int tick_is_broadcast_device(struct clock_event_device *dev)
76{
77 return (dev && tick_broadcast_device.evtdev == dev);
78}
79
80/*
81 * Check, if the device is disfunctional and a place holder, which
82 * needs to be handled by the broadcast device.
83 */
84int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
85{
86 unsigned long flags;
87 int ret = 0;
88
89 spin_lock_irqsave(&tick_broadcast_lock, flags);
90
91 /*
92 * Devices might be registered with both periodic and oneshot
93 * mode disabled. This signals, that the device needs to be
94 * operated from the broadcast device and is a placeholder for
95 * the cpu local device.
96 */
97 if (!tick_device_is_functional(dev)) {
98 dev->event_handler = tick_handle_periodic;
99 cpu_set(cpu, tick_broadcast_mask);
100 tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
101 ret = 1;
102 }
103
104 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
105 return ret;
106}
107
108/*
109 * Broadcast the event to the cpus, which are set in the mask
110 */
111int tick_do_broadcast(cpumask_t mask)
112{
113 int ret = 0, cpu = smp_processor_id();
114 struct tick_device *td;
115
116 /*
117 * Check, if the current cpu is in the mask
118 */
119 if (cpu_isset(cpu, mask)) {
120 cpu_clear(cpu, mask);
121 td = &per_cpu(tick_cpu_device, cpu);
122 td->evtdev->event_handler(td->evtdev);
123 ret = 1;
124 }
125
126 if (!cpus_empty(mask)) {
127 /*
128 * It might be necessary to actually check whether the devices
129 * have different broadcast functions. For now, just use the
130 * one of the first device. This works as long as we have this
131 * misfeature only on x86 (lapic)
132 */
133 cpu = first_cpu(mask);
134 td = &per_cpu(tick_cpu_device, cpu);
135 td->evtdev->broadcast(mask);
136 ret = 1;
137 }
138 return ret;
139}
140
141/*
142 * Periodic broadcast:
143 * - invoke the broadcast handlers
144 */
145static void tick_do_periodic_broadcast(void)
146{
147 cpumask_t mask;
148
149 spin_lock(&tick_broadcast_lock);
150
151 cpus_and(mask, cpu_online_map, tick_broadcast_mask);
152 tick_do_broadcast(mask);
153
154 spin_unlock(&tick_broadcast_lock);
155}
156
157/*
158 * Event handler for periodic broadcast ticks
159 */
160static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
161{
162 dev->next_event.tv64 = KTIME_MAX;
163
164 tick_do_periodic_broadcast();
165
166 /*
167 * The device is in periodic mode. No reprogramming necessary:
168 */
169 if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
170 return;
171
172 /*
173 * Setup the next period for devices, which do not have
174 * periodic mode:
175 */
176 for (;;) {
177 ktime_t next = ktime_add(dev->next_event, tick_period);
178
179 if (!clockevents_program_event(dev, next, ktime_get()))
180 return;
181 tick_do_periodic_broadcast();
182 }
183}
184
185/*
186 * Powerstate information: The system enters/leaves a state, where
187 * affected devices might stop
188 */
189static void tick_do_broadcast_on_off(void *why)
190{
191 struct clock_event_device *bc, *dev;
192 struct tick_device *td;
193 unsigned long flags, *reason = why;
194 int cpu;
195
196 spin_lock_irqsave(&tick_broadcast_lock, flags);
197
198 cpu = smp_processor_id();
199 td = &per_cpu(tick_cpu_device, cpu);
200 dev = td->evtdev;
201 bc = tick_broadcast_device.evtdev;
202
203 /*
204 * Is the device in broadcast mode forever or is it not
205 * affected by the powerstate ?
206 */
207 if (!dev || !tick_device_is_functional(dev) ||
208 !(dev->features & CLOCK_EVT_FEAT_C3STOP))
209 goto out;
210
211 if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_ON) {
212 if (!cpu_isset(cpu, tick_broadcast_mask)) {
213 cpu_set(cpu, tick_broadcast_mask);
214 if (td->mode == TICKDEV_MODE_PERIODIC)
215 clockevents_set_mode(dev,
216 CLOCK_EVT_MODE_SHUTDOWN);
217 }
218 } else {
219 if (cpu_isset(cpu, tick_broadcast_mask)) {
220 cpu_clear(cpu, tick_broadcast_mask);
221 if (td->mode == TICKDEV_MODE_PERIODIC)
222 tick_setup_periodic(dev, 0);
223 }
224 }
225
226 if (cpus_empty(tick_broadcast_mask))
227 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
228 else {
229 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
230 tick_broadcast_start_periodic(bc);
231 else
232 tick_broadcast_setup_oneshot(bc);
233 }
234out:
235 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
236}
237
238/*
239 * Powerstate information: The system enters/leaves a state, where
240 * affected devices might stop.
241 */
242void tick_broadcast_on_off(unsigned long reason, int *oncpu)
243{
244 int cpu = get_cpu();
245
246 if (cpu == *oncpu)
247 tick_do_broadcast_on_off(&reason);
248 else
249 smp_call_function_single(*oncpu, tick_do_broadcast_on_off,
250 &reason, 1, 1);
251 put_cpu();
252}
253
254/*
255 * Set the periodic handler depending on broadcast on/off
256 */
257void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
258{
259 if (!broadcast)
260 dev->event_handler = tick_handle_periodic;
261 else
262 dev->event_handler = tick_handle_periodic_broadcast;
263}
264
265/*
266 * Remove a CPU from broadcasting
267 */
268void tick_shutdown_broadcast(unsigned int *cpup)
269{
270 struct clock_event_device *bc;
271 unsigned long flags;
272 unsigned int cpu = *cpup;
273
274 spin_lock_irqsave(&tick_broadcast_lock, flags);
275
276 bc = tick_broadcast_device.evtdev;
277 cpu_clear(cpu, tick_broadcast_mask);
278
279 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
280 if (bc && cpus_empty(tick_broadcast_mask))
281 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
282 }
283
284 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
285}
286
287#ifdef CONFIG_TICK_ONESHOT
288
289static cpumask_t tick_broadcast_oneshot_mask;
290
291/*
292 * Debugging: see timer_list.c
293 */
294cpumask_t *tick_get_broadcast_oneshot_mask(void)
295{
296 return &tick_broadcast_oneshot_mask;
297}
298
299static int tick_broadcast_set_event(ktime_t expires, int force)
300{
301 struct clock_event_device *bc = tick_broadcast_device.evtdev;
302 ktime_t now = ktime_get();
303 int res;
304
305 for(;;) {
306 res = clockevents_program_event(bc, expires, now);
307 if (!res || !force)
308 return res;
309 now = ktime_get();
310 expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
311 }
312}
313
314/*
315 * Reprogram the broadcast device:
316 *
317 * Called with tick_broadcast_lock held and interrupts disabled.
318 */
319static int tick_broadcast_reprogram(void)
320{
321 ktime_t expires = { .tv64 = KTIME_MAX };
322 struct tick_device *td;
323 int cpu;
324
325 /*
326 * Find the event which expires next:
327 */
328 for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
329 cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
330 td = &per_cpu(tick_cpu_device, cpu);
331 if (td->evtdev->next_event.tv64 < expires.tv64)
332 expires = td->evtdev->next_event;
333 }
334
335 if (expires.tv64 == KTIME_MAX)
336 return 0;
337
338 return tick_broadcast_set_event(expires, 0);
339}
340
341/*
342 * Handle oneshot mode broadcasting
343 */
344static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
345{
346 struct tick_device *td;
347 cpumask_t mask;
348 ktime_t now;
349 int cpu;
350
351 spin_lock(&tick_broadcast_lock);
352again:
353 dev->next_event.tv64 = KTIME_MAX;
354 mask = CPU_MASK_NONE;
355 now = ktime_get();
356 /* Find all expired events */
357 for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
358 cpu = next_cpu(cpu, tick_broadcast_oneshot_mask)) {
359 td = &per_cpu(tick_cpu_device, cpu);
360 if (td->evtdev->next_event.tv64 <= now.tv64)
361 cpu_set(cpu, mask);
362 }
363
364 /*
365 * Wakeup the cpus which have an expired event. The broadcast
366 * device is reprogrammed in the return from idle code.
367 */
368 if (!tick_do_broadcast(mask)) {
369 /*
370 * The global event did not expire any CPU local
371 * events. This happens in dyntick mode, as the
372 * maximum PIT delta is quite small.
373 */
374 if (tick_broadcast_reprogram())
375 goto again;
376 }
377 spin_unlock(&tick_broadcast_lock);
378}
379
380/*
381 * Powerstate information: The system enters/leaves a state, where
382 * affected devices might stop
383 */
384void tick_broadcast_oneshot_control(unsigned long reason)
385{
386 struct clock_event_device *bc, *dev;
387 struct tick_device *td;
388 unsigned long flags;
389 int cpu;
390
391 spin_lock_irqsave(&tick_broadcast_lock, flags);
392
393 /*
394 * Periodic mode does not care about the enter/exit of power
395 * states
396 */
397 if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
398 goto out;
399
400 bc = tick_broadcast_device.evtdev;
401 cpu = smp_processor_id();
402 td = &per_cpu(tick_cpu_device, cpu);
403 dev = td->evtdev;
404
405 if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
406 goto out;
407
408 if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
409 if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
410 cpu_set(cpu, tick_broadcast_oneshot_mask);
411 clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
412 if (dev->next_event.tv64 < bc->next_event.tv64)
413 tick_broadcast_set_event(dev->next_event, 1);
414 }
415 } else {
416 if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
417 cpu_clear(cpu, tick_broadcast_oneshot_mask);
418 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
419 if (dev->next_event.tv64 != KTIME_MAX)
420 tick_program_event(dev->next_event, 1);
421 }
422 }
423
424out:
425 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
426}
427
428/**
429 * tick_broadcast_setup_highres - setup the broadcast device for highres
430 */
431void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
432{
433 if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
434 bc->event_handler = tick_handle_oneshot_broadcast;
435 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
436 bc->next_event.tv64 = KTIME_MAX;
437 }
438}
439
440/*
441 * Select oneshot operating mode for the broadcast device
442 */
443void tick_broadcast_switch_to_oneshot(void)
444{
445 struct clock_event_device *bc;
446 unsigned long flags;
447
448 spin_lock_irqsave(&tick_broadcast_lock, flags);
449
450 tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
451 bc = tick_broadcast_device.evtdev;
452 if (bc)
453 tick_broadcast_setup_oneshot(bc);
454 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
455}
456
457
458/*
459 * Remove a dead CPU from broadcasting
460 */
461void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
462{
463 struct clock_event_device *bc;
464 unsigned long flags;
465 unsigned int cpu = *cpup;
466
467 spin_lock_irqsave(&tick_broadcast_lock, flags);
468
469 bc = tick_broadcast_device.evtdev;
470 cpu_clear(cpu, tick_broadcast_oneshot_mask);
471
472 if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT) {
473 if (bc && cpus_empty(tick_broadcast_oneshot_mask))
474 clockevents_set_mode(bc, CLOCK_EVT_MODE_SHUTDOWN);
475 }
476
477 spin_unlock_irqrestore(&tick_broadcast_lock, flags);
478}
479
480#endif