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Len Brown26717172010-03-08 14:07:30 -05001/*
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>
H. Peter Anvinbc83ccc2010-09-17 15:36:40 -070062#include <asm/mwait.h>
Len Brown26717172010-03-08 14:07:30 -050063
64#define INTEL_IDLE_VERSION "0.4"
65#define PREFIX "intel_idle: "
66
Len Brown26717172010-03-08 14:07:30 -050067static struct cpuidle_driver intel_idle_driver = {
68 .name = "intel_idle",
69 .owner = THIS_MODULE,
70};
71/* intel_idle.max_cstate=0 disables driver */
72static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
Len Brown26717172010-03-08 14:07:30 -050073
Len Brownc4236282010-05-28 02:22:03 -040074static unsigned int mwait_substates;
Len Brown26717172010-03-08 14:07:30 -050075
76/* Reliable LAPIC Timer States, bit 1 for C1 etc. */
Len Brownd13780d2010-07-07 00:12:03 -040077static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */
Len Brown26717172010-03-08 14:07:30 -050078
Namhyung Kim3265eba2010-08-08 03:10:03 +090079static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
Len Brown26717172010-03-08 14:07:30 -050080static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state);
81
82static struct cpuidle_state *cpuidle_state_table;
83
84/*
85 * States are indexed by the cstate number,
86 * which is also the index into the MWAIT hint array.
87 * Thus C0 is a dummy.
88 */
89static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
90 { /* MWAIT C0 */ },
91 { /* MWAIT C1 */
92 .name = "NHM-C1",
93 .desc = "MWAIT 0x00",
94 .driver_data = (void *) 0x00,
95 .flags = CPUIDLE_FLAG_TIME_VALID,
96 .exit_latency = 3,
Len Brown26717172010-03-08 14:07:30 -050097 .target_residency = 6,
98 .enter = &intel_idle },
99 { /* MWAIT C2 */
100 .name = "NHM-C3",
101 .desc = "MWAIT 0x10",
102 .driver_data = (void *) 0x10,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400103 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown26717172010-03-08 14:07:30 -0500104 .exit_latency = 20,
Len Brown26717172010-03-08 14:07:30 -0500105 .target_residency = 80,
106 .enter = &intel_idle },
107 { /* MWAIT C3 */
108 .name = "NHM-C6",
109 .desc = "MWAIT 0x20",
110 .driver_data = (void *) 0x20,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400111 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown26717172010-03-08 14:07:30 -0500112 .exit_latency = 200,
Len Brown26717172010-03-08 14:07:30 -0500113 .target_residency = 800,
114 .enter = &intel_idle },
115};
116
Len Brownd13780d2010-07-07 00:12:03 -0400117static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
118 { /* MWAIT C0 */ },
119 { /* MWAIT C1 */
120 .name = "SNB-C1",
121 .desc = "MWAIT 0x00",
122 .driver_data = (void *) 0x00,
123 .flags = CPUIDLE_FLAG_TIME_VALID,
124 .exit_latency = 1,
Len Brownddbd5502010-12-13 18:28:22 -0500125 .target_residency = 1,
Len Brownd13780d2010-07-07 00:12:03 -0400126 .enter = &intel_idle },
127 { /* MWAIT C2 */
128 .name = "SNB-C3",
129 .desc = "MWAIT 0x10",
130 .driver_data = (void *) 0x10,
Len Brown00527cc2010-10-23 02:33:50 -0400131 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brownd13780d2010-07-07 00:12:03 -0400132 .exit_latency = 80,
Len Brownddbd5502010-12-13 18:28:22 -0500133 .target_residency = 211,
Len Brownd13780d2010-07-07 00:12:03 -0400134 .enter = &intel_idle },
135 { /* MWAIT C3 */
136 .name = "SNB-C6",
137 .desc = "MWAIT 0x20",
138 .driver_data = (void *) 0x20,
Len Brown00527cc2010-10-23 02:33:50 -0400139 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brownd13780d2010-07-07 00:12:03 -0400140 .exit_latency = 104,
Len Brownddbd5502010-12-13 18:28:22 -0500141 .target_residency = 345,
Len Brownd13780d2010-07-07 00:12:03 -0400142 .enter = &intel_idle },
143 { /* MWAIT C4 */
144 .name = "SNB-C7",
145 .desc = "MWAIT 0x30",
146 .driver_data = (void *) 0x30,
Len Brown00527cc2010-10-23 02:33:50 -0400147 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brownd13780d2010-07-07 00:12:03 -0400148 .exit_latency = 109,
Len Brownddbd5502010-12-13 18:28:22 -0500149 .target_residency = 345,
Len Brownd13780d2010-07-07 00:12:03 -0400150 .enter = &intel_idle },
151};
152
Len Brown26717172010-03-08 14:07:30 -0500153static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
154 { /* MWAIT C0 */ },
155 { /* MWAIT C1 */
156 .name = "ATM-C1",
157 .desc = "MWAIT 0x00",
158 .driver_data = (void *) 0x00,
159 .flags = CPUIDLE_FLAG_TIME_VALID,
160 .exit_latency = 1,
Len Brown26717172010-03-08 14:07:30 -0500161 .target_residency = 4,
162 .enter = &intel_idle },
163 { /* MWAIT C2 */
164 .name = "ATM-C2",
165 .desc = "MWAIT 0x10",
166 .driver_data = (void *) 0x10,
167 .flags = CPUIDLE_FLAG_TIME_VALID,
168 .exit_latency = 20,
Len Brown26717172010-03-08 14:07:30 -0500169 .target_residency = 80,
170 .enter = &intel_idle },
171 { /* MWAIT C3 */ },
172 { /* MWAIT C4 */
173 .name = "ATM-C4",
174 .desc = "MWAIT 0x30",
175 .driver_data = (void *) 0x30,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400176 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown26717172010-03-08 14:07:30 -0500177 .exit_latency = 100,
Len Brown26717172010-03-08 14:07:30 -0500178 .target_residency = 400,
179 .enter = &intel_idle },
180 { /* MWAIT C5 */ },
181 { /* MWAIT C6 */
182 .name = "ATM-C6",
Len Brown7fcca7d2010-10-05 13:43:14 -0400183 .desc = "MWAIT 0x52",
184 .driver_data = (void *) 0x52,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400185 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown7fcca7d2010-10-05 13:43:14 -0400186 .exit_latency = 140,
Len Brown7fcca7d2010-10-05 13:43:14 -0400187 .target_residency = 560,
188 .enter = &intel_idle },
Len Brown26717172010-03-08 14:07:30 -0500189};
190
Len Brown26717172010-03-08 14:07:30 -0500191/**
192 * intel_idle
193 * @dev: cpuidle_device
194 * @state: cpuidle state
195 *
196 */
197static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
198{
199 unsigned long ecx = 1; /* break on interrupt flag */
200 unsigned long eax = (unsigned long)cpuidle_get_statedata(state);
201 unsigned int cstate;
202 ktime_t kt_before, kt_after;
203 s64 usec_delta;
204 int cpu = smp_processor_id();
205
206 cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
207
Len Brown26717172010-03-08 14:07:30 -0500208 local_irq_disable();
209
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400210 /*
Len Brownc8381cc2010-10-15 20:43:06 -0400211 * leave_mm() to avoid costly and often unnecessary wakeups
212 * for flushing the user TLB's associated with the active mm.
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400213 */
Len Brownc8381cc2010-10-15 20:43:06 -0400214 if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400215 leave_mm(cpu);
216
Len Brown26717172010-03-08 14:07:30 -0500217 if (!(lapic_timer_reliable_states & (1 << (cstate))))
218 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
219
220 kt_before = ktime_get_real();
221
222 stop_critical_timings();
223#ifndef MODULE
Linus Torvalds8d915302010-08-04 11:13:36 -0700224 trace_power_start(POWER_CSTATE, (eax >> 4) + 1, cpu);
Len Brown26717172010-03-08 14:07:30 -0500225#endif
226 if (!need_resched()) {
227
228 __monitor((void *)&current_thread_info()->flags, 0, 0);
229 smp_mb();
230 if (!need_resched())
231 __mwait(eax, ecx);
232 }
233
234 start_critical_timings();
235
236 kt_after = ktime_get_real();
237 usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
238
239 local_irq_enable();
240
241 if (!(lapic_timer_reliable_states & (1 << (cstate))))
242 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
243
244 return usec_delta;
245}
246
247/*
248 * intel_idle_probe()
249 */
250static int intel_idle_probe(void)
251{
Len Brownc4236282010-05-28 02:22:03 -0400252 unsigned int eax, ebx, ecx;
Len Brown26717172010-03-08 14:07:30 -0500253
254 if (max_cstate == 0) {
255 pr_debug(PREFIX "disabled\n");
256 return -EPERM;
257 }
258
259 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
260 return -ENODEV;
261
262 if (!boot_cpu_has(X86_FEATURE_MWAIT))
263 return -ENODEV;
264
265 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
266 return -ENODEV;
267
Len Brownc4236282010-05-28 02:22:03 -0400268 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
Len Brown26717172010-03-08 14:07:30 -0500269
270 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
271 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
272 return -ENODEV;
Len Brown26717172010-03-08 14:07:30 -0500273
Len Brownc4236282010-05-28 02:22:03 -0400274 pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
Len Brown26717172010-03-08 14:07:30 -0500275
Len Brown26717172010-03-08 14:07:30 -0500276
277 if (boot_cpu_data.x86 != 6) /* family 6 */
278 return -ENODEV;
279
280 switch (boot_cpu_data.x86_model) {
281
282 case 0x1A: /* Core i7, Xeon 5500 series */
283 case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */
284 case 0x1F: /* Core i7 and i5 Processor - Nehalem */
285 case 0x2E: /* Nehalem-EX Xeon */
Len Brownec67a2b2010-07-26 23:40:19 -0400286 case 0x2F: /* Westmere-EX Xeon */
Len Brown26717172010-03-08 14:07:30 -0500287 case 0x25: /* Westmere */
288 case 0x2C: /* Westmere */
289 cpuidle_state_table = nehalem_cstates;
Len Brown26717172010-03-08 14:07:30 -0500290 break;
291
292 case 0x1C: /* 28 - Atom Processor */
Arjan van de Ven4725fd32010-07-21 23:42:25 -0400293 case 0x26: /* 38 - Lincroft Atom Processor */
Len Brown26717172010-03-08 14:07:30 -0500294 cpuidle_state_table = atom_cstates;
Len Brown26717172010-03-08 14:07:30 -0500295 break;
Len Brownd13780d2010-07-07 00:12:03 -0400296
297 case 0x2A: /* SNB */
298 case 0x2D: /* SNB Xeon */
299 cpuidle_state_table = snb_cstates;
Len Brownd13780d2010-07-07 00:12:03 -0400300 break;
Len Brown26717172010-03-08 14:07:30 -0500301
302 default:
303 pr_debug(PREFIX "does not run on family %d model %d\n",
304 boot_cpu_data.x86, boot_cpu_data.x86_model);
305 return -ENODEV;
306 }
307
Len Brown56b9aea2010-12-02 01:19:32 -0500308 if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
309 lapic_timer_reliable_states = 0xFFFFFFFF;
310
Len Brown26717172010-03-08 14:07:30 -0500311 pr_debug(PREFIX "v" INTEL_IDLE_VERSION
312 " model 0x%X\n", boot_cpu_data.x86_model);
313
314 pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
315 lapic_timer_reliable_states);
316 return 0;
317}
318
319/*
320 * intel_idle_cpuidle_devices_uninit()
321 * unregister, free cpuidle_devices
322 */
323static void intel_idle_cpuidle_devices_uninit(void)
324{
325 int i;
326 struct cpuidle_device *dev;
327
328 for_each_online_cpu(i) {
329 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
330 cpuidle_unregister_device(dev);
331 }
332
333 free_percpu(intel_idle_cpuidle_devices);
334 return;
335}
336/*
337 * intel_idle_cpuidle_devices_init()
338 * allocate, initialize, register cpuidle_devices
339 */
340static int intel_idle_cpuidle_devices_init(void)
341{
342 int i, cstate;
343 struct cpuidle_device *dev;
344
345 intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
346 if (intel_idle_cpuidle_devices == NULL)
347 return -ENOMEM;
348
349 for_each_online_cpu(i) {
350 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
351
352 dev->state_count = 1;
353
354 for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
355 int num_substates;
356
357 if (cstate > max_cstate) {
358 printk(PREFIX "max_cstate %d reached\n",
359 max_cstate);
360 break;
361 }
362
363 /* does the state exist in CPUID.MWAIT? */
Len Brownc4236282010-05-28 02:22:03 -0400364 num_substates = (mwait_substates >> ((cstate) * 4))
Len Brown26717172010-03-08 14:07:30 -0500365 & MWAIT_SUBSTATE_MASK;
366 if (num_substates == 0)
367 continue;
368 /* is the state not enabled? */
369 if (cpuidle_state_table[cstate].enter == NULL) {
370 /* does the driver not know about the state? */
371 if (*cpuidle_state_table[cstate].name == '\0')
372 pr_debug(PREFIX "unaware of model 0x%x"
373 " MWAIT %d please"
374 " contact lenb@kernel.org",
375 boot_cpu_data.x86_model, cstate);
376 continue;
377 }
378
379 if ((cstate > 2) &&
380 !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
381 mark_tsc_unstable("TSC halts in idle"
382 " states deeper than C2");
383
384 dev->states[dev->state_count] = /* structure copy */
385 cpuidle_state_table[cstate];
386
387 dev->state_count += 1;
388 }
389
390 dev->cpu = i;
391 if (cpuidle_register_device(dev)) {
392 pr_debug(PREFIX "cpuidle_register_device %d failed!\n",
393 i);
394 intel_idle_cpuidle_devices_uninit();
395 return -EIO;
396 }
397 }
398
399 return 0;
400}
401
402
403static int __init intel_idle_init(void)
404{
405 int retval;
406
407 retval = intel_idle_probe();
408 if (retval)
409 return retval;
410
411 retval = cpuidle_register_driver(&intel_idle_driver);
412 if (retval) {
413 printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
414 cpuidle_get_driver()->name);
415 return retval;
416 }
417
418 retval = intel_idle_cpuidle_devices_init();
419 if (retval) {
420 cpuidle_unregister_driver(&intel_idle_driver);
421 return retval;
422 }
423
424 return 0;
425}
426
427static void __exit intel_idle_exit(void)
428{
429 intel_idle_cpuidle_devices_uninit();
430 cpuidle_unregister_driver(&intel_idle_driver);
431
432 return;
433}
434
435module_init(intel_idle_init);
436module_exit(intel_idle_exit);
437
Len Brown26717172010-03-08 14:07:30 -0500438module_param(max_cstate, int, 0444);
Len Brown26717172010-03-08 14:07:30 -0500439
440MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
441MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
442MODULE_LICENSE("GPL");