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26717172 LB |
1 | /* |
2 | * intel_idle.c - native hardware idle loop for modern Intel processors | |
3 | * | |
4 | * Copyright (c) 2010, Intel Corporation. | |
5 | * Len Brown <len.brown@intel.com> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify it | |
8 | * under the terms and conditions of the GNU General Public License, | |
9 | * version 2, as published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope it will be useful, but WITHOUT | |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
14 | * more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License along with | |
17 | * this program; if not, write to the Free Software Foundation, Inc., | |
18 | * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. | |
19 | */ | |
20 | ||
21 | /* | |
22 | * intel_idle is a cpuidle driver that loads on specific Intel processors | |
23 | * in lieu of the legacy ACPI processor_idle driver. The intent is to | |
24 | * make Linux more efficient on these processors, as intel_idle knows | |
25 | * more than ACPI, as well as make Linux more immune to ACPI BIOS bugs. | |
26 | */ | |
27 | ||
28 | /* | |
29 | * Design Assumptions | |
30 | * | |
31 | * All CPUs have same idle states as boot CPU | |
32 | * | |
33 | * Chipset BM_STS (bus master status) bit is a NOP | |
34 | * for preventing entry into deep C-stats | |
35 | */ | |
36 | ||
37 | /* | |
38 | * Known limitations | |
39 | * | |
40 | * The driver currently initializes for_each_online_cpu() upon modprobe. | |
41 | * It it unaware of subsequent processors hot-added to the system. | |
42 | * This means that if you boot with maxcpus=n and later online | |
43 | * processors above n, those processors will use C1 only. | |
44 | * | |
45 | * ACPI has a .suspend hack to turn off deep c-statees during suspend | |
46 | * to avoid complications with the lapic timer workaround. | |
47 | * Have not seen issues with suspend, but may need same workaround here. | |
48 | * | |
49 | * There is currently no kernel-based automatic probing/loading mechanism | |
50 | * if the driver is built as a module. | |
51 | */ | |
52 | ||
53 | /* un-comment DEBUG to enable pr_debug() statements */ | |
54 | #define DEBUG | |
55 | ||
56 | #include <linux/kernel.h> | |
57 | #include <linux/cpuidle.h> | |
58 | #include <linux/clockchips.h> | |
59 | #include <linux/hrtimer.h> /* ktime_get_real() */ | |
60 | #include <trace/events/power.h> | |
61 | #include <linux/sched.h> | |
2a2d31c8 SL |
62 | #include <linux/notifier.h> |
63 | #include <linux/cpu.h> | |
bc83cccc | 64 | #include <asm/mwait.h> |
26717172 LB |
65 | |
66 | #define INTEL_IDLE_VERSION "0.4" | |
67 | #define PREFIX "intel_idle: " | |
68 | ||
26717172 LB |
69 | static struct cpuidle_driver intel_idle_driver = { |
70 | .name = "intel_idle", | |
71 | .owner = THIS_MODULE, | |
72 | }; | |
73 | /* intel_idle.max_cstate=0 disables driver */ | |
74 | static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1; | |
26717172 | 75 | |
c4236282 | 76 | static unsigned int mwait_substates; |
26717172 | 77 | |
2a2d31c8 | 78 | #define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF |
26717172 | 79 | /* Reliable LAPIC Timer States, bit 1 for C1 etc. */ |
d13780d4 | 80 | static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */ |
26717172 | 81 | |
3265eba0 | 82 | static struct cpuidle_device __percpu *intel_idle_cpuidle_devices; |
26717172 LB |
83 | static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state); |
84 | ||
85 | static struct cpuidle_state *cpuidle_state_table; | |
86 | ||
956d033f LB |
87 | /* |
88 | * Set this flag for states where the HW flushes the TLB for us | |
89 | * and so we don't need cross-calls to keep it consistent. | |
90 | * If this flag is set, SW flushes the TLB, so even if the | |
91 | * HW doesn't do the flushing, this flag is safe to use. | |
92 | */ | |
93 | #define CPUIDLE_FLAG_TLB_FLUSHED 0x10000 | |
94 | ||
26717172 LB |
95 | /* |
96 | * States are indexed by the cstate number, | |
97 | * which is also the index into the MWAIT hint array. | |
98 | * Thus C0 is a dummy. | |
99 | */ | |
100 | static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = { | |
101 | { /* MWAIT C0 */ }, | |
102 | { /* MWAIT C1 */ | |
103 | .name = "NHM-C1", | |
104 | .desc = "MWAIT 0x00", | |
105 | .driver_data = (void *) 0x00, | |
106 | .flags = CPUIDLE_FLAG_TIME_VALID, | |
107 | .exit_latency = 3, | |
26717172 LB |
108 | .target_residency = 6, |
109 | .enter = &intel_idle }, | |
110 | { /* MWAIT C2 */ | |
111 | .name = "NHM-C3", | |
112 | .desc = "MWAIT 0x10", | |
113 | .driver_data = (void *) 0x10, | |
6110a1f4 | 114 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
26717172 | 115 | .exit_latency = 20, |
26717172 LB |
116 | .target_residency = 80, |
117 | .enter = &intel_idle }, | |
118 | { /* MWAIT C3 */ | |
119 | .name = "NHM-C6", | |
120 | .desc = "MWAIT 0x20", | |
121 | .driver_data = (void *) 0x20, | |
6110a1f4 | 122 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
26717172 | 123 | .exit_latency = 200, |
26717172 LB |
124 | .target_residency = 800, |
125 | .enter = &intel_idle }, | |
126 | }; | |
127 | ||
d13780d4 LB |
128 | static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = { |
129 | { /* MWAIT C0 */ }, | |
130 | { /* MWAIT C1 */ | |
131 | .name = "SNB-C1", | |
132 | .desc = "MWAIT 0x00", | |
133 | .driver_data = (void *) 0x00, | |
134 | .flags = CPUIDLE_FLAG_TIME_VALID, | |
135 | .exit_latency = 1, | |
ddbd550d | 136 | .target_residency = 1, |
d13780d4 LB |
137 | .enter = &intel_idle }, |
138 | { /* MWAIT C2 */ | |
139 | .name = "SNB-C3", | |
140 | .desc = "MWAIT 0x10", | |
141 | .driver_data = (void *) 0x10, | |
00527cc6 | 142 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
d13780d4 | 143 | .exit_latency = 80, |
ddbd550d | 144 | .target_residency = 211, |
d13780d4 LB |
145 | .enter = &intel_idle }, |
146 | { /* MWAIT C3 */ | |
147 | .name = "SNB-C6", | |
148 | .desc = "MWAIT 0x20", | |
149 | .driver_data = (void *) 0x20, | |
00527cc6 | 150 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
d13780d4 | 151 | .exit_latency = 104, |
ddbd550d | 152 | .target_residency = 345, |
d13780d4 LB |
153 | .enter = &intel_idle }, |
154 | { /* MWAIT C4 */ | |
155 | .name = "SNB-C7", | |
156 | .desc = "MWAIT 0x30", | |
157 | .driver_data = (void *) 0x30, | |
00527cc6 | 158 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
d13780d4 | 159 | .exit_latency = 109, |
ddbd550d | 160 | .target_residency = 345, |
d13780d4 LB |
161 | .enter = &intel_idle }, |
162 | }; | |
163 | ||
26717172 LB |
164 | static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = { |
165 | { /* MWAIT C0 */ }, | |
166 | { /* MWAIT C1 */ | |
167 | .name = "ATM-C1", | |
168 | .desc = "MWAIT 0x00", | |
169 | .driver_data = (void *) 0x00, | |
170 | .flags = CPUIDLE_FLAG_TIME_VALID, | |
171 | .exit_latency = 1, | |
26717172 LB |
172 | .target_residency = 4, |
173 | .enter = &intel_idle }, | |
174 | { /* MWAIT C2 */ | |
175 | .name = "ATM-C2", | |
176 | .desc = "MWAIT 0x10", | |
177 | .driver_data = (void *) 0x10, | |
178 | .flags = CPUIDLE_FLAG_TIME_VALID, | |
179 | .exit_latency = 20, | |
26717172 LB |
180 | .target_residency = 80, |
181 | .enter = &intel_idle }, | |
182 | { /* MWAIT C3 */ }, | |
183 | { /* MWAIT C4 */ | |
184 | .name = "ATM-C4", | |
185 | .desc = "MWAIT 0x30", | |
186 | .driver_data = (void *) 0x30, | |
6110a1f4 | 187 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
26717172 | 188 | .exit_latency = 100, |
26717172 LB |
189 | .target_residency = 400, |
190 | .enter = &intel_idle }, | |
191 | { /* MWAIT C5 */ }, | |
192 | { /* MWAIT C6 */ | |
193 | .name = "ATM-C6", | |
7fcca7d9 LB |
194 | .desc = "MWAIT 0x52", |
195 | .driver_data = (void *) 0x52, | |
6110a1f4 | 196 | .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED, |
7fcca7d9 | 197 | .exit_latency = 140, |
7fcca7d9 LB |
198 | .target_residency = 560, |
199 | .enter = &intel_idle }, | |
26717172 LB |
200 | }; |
201 | ||
26717172 LB |
202 | /** |
203 | * intel_idle | |
204 | * @dev: cpuidle_device | |
205 | * @state: cpuidle state | |
206 | * | |
207 | */ | |
208 | static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state) | |
209 | { | |
210 | unsigned long ecx = 1; /* break on interrupt flag */ | |
211 | unsigned long eax = (unsigned long)cpuidle_get_statedata(state); | |
212 | unsigned int cstate; | |
213 | ktime_t kt_before, kt_after; | |
214 | s64 usec_delta; | |
215 | int cpu = smp_processor_id(); | |
216 | ||
217 | cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1; | |
218 | ||
26717172 LB |
219 | local_irq_disable(); |
220 | ||
6110a1f4 | 221 | /* |
c8381cc3 LB |
222 | * leave_mm() to avoid costly and often unnecessary wakeups |
223 | * for flushing the user TLB's associated with the active mm. | |
6110a1f4 | 224 | */ |
c8381cc3 | 225 | if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED) |
6110a1f4 SS |
226 | leave_mm(cpu); |
227 | ||
26717172 LB |
228 | if (!(lapic_timer_reliable_states & (1 << (cstate)))) |
229 | clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); | |
230 | ||
231 | kt_before = ktime_get_real(); | |
232 | ||
233 | stop_critical_timings(); | |
26717172 LB |
234 | if (!need_resched()) { |
235 | ||
236 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
237 | smp_mb(); | |
238 | if (!need_resched()) | |
239 | __mwait(eax, ecx); | |
240 | } | |
241 | ||
242 | start_critical_timings(); | |
243 | ||
244 | kt_after = ktime_get_real(); | |
245 | usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before)); | |
246 | ||
247 | local_irq_enable(); | |
248 | ||
249 | if (!(lapic_timer_reliable_states & (1 << (cstate)))) | |
250 | clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); | |
251 | ||
252 | return usec_delta; | |
253 | } | |
254 | ||
2a2d31c8 SL |
255 | static void __setup_broadcast_timer(void *arg) |
256 | { | |
257 | unsigned long reason = (unsigned long)arg; | |
258 | int cpu = smp_processor_id(); | |
259 | ||
260 | reason = reason ? | |
261 | CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF; | |
262 | ||
263 | clockevents_notify(reason, &cpu); | |
264 | } | |
265 | ||
ec30f343 | 266 | static int setup_broadcast_cpuhp_notify(struct notifier_block *n, |
2a2d31c8 SL |
267 | unsigned long action, void *hcpu) |
268 | { | |
269 | int hotcpu = (unsigned long)hcpu; | |
270 | ||
271 | switch (action & 0xf) { | |
272 | case CPU_ONLINE: | |
273 | smp_call_function_single(hotcpu, __setup_broadcast_timer, | |
274 | (void *)true, 1); | |
275 | break; | |
2a2d31c8 SL |
276 | } |
277 | return NOTIFY_OK; | |
278 | } | |
279 | ||
ec30f343 | 280 | static struct notifier_block setup_broadcast_notifier = { |
2a2d31c8 SL |
281 | .notifier_call = setup_broadcast_cpuhp_notify, |
282 | }; | |
283 | ||
26717172 LB |
284 | /* |
285 | * intel_idle_probe() | |
286 | */ | |
287 | static int intel_idle_probe(void) | |
288 | { | |
c4236282 | 289 | unsigned int eax, ebx, ecx; |
26717172 LB |
290 | |
291 | if (max_cstate == 0) { | |
292 | pr_debug(PREFIX "disabled\n"); | |
293 | return -EPERM; | |
294 | } | |
295 | ||
296 | if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) | |
297 | return -ENODEV; | |
298 | ||
299 | if (!boot_cpu_has(X86_FEATURE_MWAIT)) | |
300 | return -ENODEV; | |
301 | ||
302 | if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) | |
303 | return -ENODEV; | |
304 | ||
c4236282 | 305 | cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates); |
26717172 LB |
306 | |
307 | if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || | |
308 | !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) | |
309 | return -ENODEV; | |
26717172 | 310 | |
c4236282 | 311 | pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates); |
26717172 | 312 | |
26717172 LB |
313 | |
314 | if (boot_cpu_data.x86 != 6) /* family 6 */ | |
315 | return -ENODEV; | |
316 | ||
317 | switch (boot_cpu_data.x86_model) { | |
318 | ||
319 | case 0x1A: /* Core i7, Xeon 5500 series */ | |
320 | case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */ | |
321 | case 0x1F: /* Core i7 and i5 Processor - Nehalem */ | |
322 | case 0x2E: /* Nehalem-EX Xeon */ | |
ec67a2ba | 323 | case 0x2F: /* Westmere-EX Xeon */ |
26717172 LB |
324 | case 0x25: /* Westmere */ |
325 | case 0x2C: /* Westmere */ | |
326 | cpuidle_state_table = nehalem_cstates; | |
26717172 LB |
327 | break; |
328 | ||
329 | case 0x1C: /* 28 - Atom Processor */ | |
4725fd3c | 330 | case 0x26: /* 38 - Lincroft Atom Processor */ |
26717172 | 331 | cpuidle_state_table = atom_cstates; |
26717172 | 332 | break; |
d13780d4 LB |
333 | |
334 | case 0x2A: /* SNB */ | |
335 | case 0x2D: /* SNB Xeon */ | |
336 | cpuidle_state_table = snb_cstates; | |
d13780d4 | 337 | break; |
26717172 LB |
338 | |
339 | default: | |
340 | pr_debug(PREFIX "does not run on family %d model %d\n", | |
341 | boot_cpu_data.x86, boot_cpu_data.x86_model); | |
342 | return -ENODEV; | |
343 | } | |
344 | ||
56b9aea3 | 345 | if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */ |
2a2d31c8 SL |
346 | lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE; |
347 | else { | |
348 | smp_call_function(__setup_broadcast_timer, (void *)true, 1); | |
349 | register_cpu_notifier(&setup_broadcast_notifier); | |
350 | } | |
56b9aea3 | 351 | |
26717172 LB |
352 | pr_debug(PREFIX "v" INTEL_IDLE_VERSION |
353 | " model 0x%X\n", boot_cpu_data.x86_model); | |
354 | ||
355 | pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n", | |
356 | lapic_timer_reliable_states); | |
357 | return 0; | |
358 | } | |
359 | ||
360 | /* | |
361 | * intel_idle_cpuidle_devices_uninit() | |
362 | * unregister, free cpuidle_devices | |
363 | */ | |
364 | static void intel_idle_cpuidle_devices_uninit(void) | |
365 | { | |
366 | int i; | |
367 | struct cpuidle_device *dev; | |
368 | ||
369 | for_each_online_cpu(i) { | |
370 | dev = per_cpu_ptr(intel_idle_cpuidle_devices, i); | |
371 | cpuidle_unregister_device(dev); | |
372 | } | |
373 | ||
374 | free_percpu(intel_idle_cpuidle_devices); | |
375 | return; | |
376 | } | |
377 | /* | |
378 | * intel_idle_cpuidle_devices_init() | |
379 | * allocate, initialize, register cpuidle_devices | |
380 | */ | |
381 | static int intel_idle_cpuidle_devices_init(void) | |
382 | { | |
383 | int i, cstate; | |
384 | struct cpuidle_device *dev; | |
385 | ||
386 | intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device); | |
387 | if (intel_idle_cpuidle_devices == NULL) | |
388 | return -ENOMEM; | |
389 | ||
390 | for_each_online_cpu(i) { | |
391 | dev = per_cpu_ptr(intel_idle_cpuidle_devices, i); | |
392 | ||
393 | dev->state_count = 1; | |
394 | ||
395 | for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) { | |
396 | int num_substates; | |
397 | ||
398 | if (cstate > max_cstate) { | |
399 | printk(PREFIX "max_cstate %d reached\n", | |
400 | max_cstate); | |
401 | break; | |
402 | } | |
403 | ||
404 | /* does the state exist in CPUID.MWAIT? */ | |
c4236282 | 405 | num_substates = (mwait_substates >> ((cstate) * 4)) |
26717172 LB |
406 | & MWAIT_SUBSTATE_MASK; |
407 | if (num_substates == 0) | |
408 | continue; | |
409 | /* is the state not enabled? */ | |
410 | if (cpuidle_state_table[cstate].enter == NULL) { | |
411 | /* does the driver not know about the state? */ | |
412 | if (*cpuidle_state_table[cstate].name == '\0') | |
413 | pr_debug(PREFIX "unaware of model 0x%x" | |
414 | " MWAIT %d please" | |
415 | " contact lenb@kernel.org", | |
416 | boot_cpu_data.x86_model, cstate); | |
417 | continue; | |
418 | } | |
419 | ||
420 | if ((cstate > 2) && | |
421 | !boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) | |
422 | mark_tsc_unstable("TSC halts in idle" | |
423 | " states deeper than C2"); | |
424 | ||
425 | dev->states[dev->state_count] = /* structure copy */ | |
426 | cpuidle_state_table[cstate]; | |
427 | ||
428 | dev->state_count += 1; | |
429 | } | |
430 | ||
431 | dev->cpu = i; | |
432 | if (cpuidle_register_device(dev)) { | |
433 | pr_debug(PREFIX "cpuidle_register_device %d failed!\n", | |
434 | i); | |
435 | intel_idle_cpuidle_devices_uninit(); | |
436 | return -EIO; | |
437 | } | |
438 | } | |
439 | ||
440 | return 0; | |
441 | } | |
442 | ||
443 | ||
444 | static int __init intel_idle_init(void) | |
445 | { | |
446 | int retval; | |
447 | ||
d1896049 TR |
448 | /* Do not load intel_idle at all for now if idle= is passed */ |
449 | if (boot_option_idle_override != IDLE_NO_OVERRIDE) | |
450 | return -ENODEV; | |
451 | ||
26717172 LB |
452 | retval = intel_idle_probe(); |
453 | if (retval) | |
454 | return retval; | |
455 | ||
456 | retval = cpuidle_register_driver(&intel_idle_driver); | |
457 | if (retval) { | |
458 | printk(KERN_DEBUG PREFIX "intel_idle yielding to %s", | |
459 | cpuidle_get_driver()->name); | |
460 | return retval; | |
461 | } | |
462 | ||
463 | retval = intel_idle_cpuidle_devices_init(); | |
464 | if (retval) { | |
465 | cpuidle_unregister_driver(&intel_idle_driver); | |
466 | return retval; | |
467 | } | |
468 | ||
469 | return 0; | |
470 | } | |
471 | ||
472 | static void __exit intel_idle_exit(void) | |
473 | { | |
474 | intel_idle_cpuidle_devices_uninit(); | |
475 | cpuidle_unregister_driver(&intel_idle_driver); | |
476 | ||
2a2d31c8 SL |
477 | if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) { |
478 | smp_call_function(__setup_broadcast_timer, (void *)false, 1); | |
479 | unregister_cpu_notifier(&setup_broadcast_notifier); | |
480 | } | |
481 | ||
26717172 LB |
482 | return; |
483 | } | |
484 | ||
485 | module_init(intel_idle_init); | |
486 | module_exit(intel_idle_exit); | |
487 | ||
26717172 | 488 | module_param(max_cstate, int, 0444); |
26717172 LB |
489 | |
490 | MODULE_AUTHOR("Len Brown <len.brown@intel.com>"); | |
491 | MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION); | |
492 | MODULE_LICENSE("GPL"); |