blob: 0906fc5b69b9af8d794d9de29277a3cee16433ed [file] [log] [blame]
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>
62
63#define INTEL_IDLE_VERSION "0.4"
64#define PREFIX "intel_idle: "
65
66#define MWAIT_SUBSTATE_MASK (0xf)
67#define MWAIT_CSTATE_MASK (0xf)
68#define MWAIT_SUBSTATE_SIZE (4)
69#define MWAIT_MAX_NUM_CSTATES 8
70#define CPUID_MWAIT_LEAF (5)
71#define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
72#define CPUID5_ECX_INTERRUPT_BREAK (0x2)
73
74static struct cpuidle_driver intel_idle_driver = {
75 .name = "intel_idle",
76 .owner = THIS_MODULE,
77};
78/* intel_idle.max_cstate=0 disables driver */
79static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
Len Brown26717172010-03-08 14:07:30 -050080
Len Brownc4236282010-05-28 02:22:03 -040081static unsigned int mwait_substates;
Len Brown26717172010-03-08 14:07:30 -050082
83/* Reliable LAPIC Timer States, bit 1 for C1 etc. */
84static unsigned int lapic_timer_reliable_states;
85
Namhyung Kim3265eba2010-08-08 03:10:03 +090086static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
Len Brown26717172010-03-08 14:07:30 -050087static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state);
88
89static struct cpuidle_state *cpuidle_state_table;
90
91/*
92 * States are indexed by the cstate number,
93 * which is also the index into the MWAIT hint array.
94 * Thus C0 is a dummy.
95 */
96static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
97 { /* MWAIT C0 */ },
98 { /* MWAIT C1 */
99 .name = "NHM-C1",
100 .desc = "MWAIT 0x00",
101 .driver_data = (void *) 0x00,
102 .flags = CPUIDLE_FLAG_TIME_VALID,
103 .exit_latency = 3,
104 .power_usage = 1000,
105 .target_residency = 6,
106 .enter = &intel_idle },
107 { /* MWAIT C2 */
108 .name = "NHM-C3",
109 .desc = "MWAIT 0x10",
110 .driver_data = (void *) 0x10,
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 = 20,
113 .power_usage = 500,
114 .target_residency = 80,
115 .enter = &intel_idle },
116 { /* MWAIT C3 */
117 .name = "NHM-C6",
118 .desc = "MWAIT 0x20",
119 .driver_data = (void *) 0x20,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400120 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown26717172010-03-08 14:07:30 -0500121 .exit_latency = 200,
122 .power_usage = 350,
123 .target_residency = 800,
124 .enter = &intel_idle },
125};
126
127static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
128 { /* MWAIT C0 */ },
129 { /* MWAIT C1 */
130 .name = "ATM-C1",
131 .desc = "MWAIT 0x00",
132 .driver_data = (void *) 0x00,
133 .flags = CPUIDLE_FLAG_TIME_VALID,
134 .exit_latency = 1,
135 .power_usage = 1000,
136 .target_residency = 4,
137 .enter = &intel_idle },
138 { /* MWAIT C2 */
139 .name = "ATM-C2",
140 .desc = "MWAIT 0x10",
141 .driver_data = (void *) 0x10,
142 .flags = CPUIDLE_FLAG_TIME_VALID,
143 .exit_latency = 20,
144 .power_usage = 500,
145 .target_residency = 80,
146 .enter = &intel_idle },
147 { /* MWAIT C3 */ },
148 { /* MWAIT C4 */
149 .name = "ATM-C4",
150 .desc = "MWAIT 0x30",
151 .driver_data = (void *) 0x30,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400152 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown26717172010-03-08 14:07:30 -0500153 .exit_latency = 100,
154 .power_usage = 250,
155 .target_residency = 400,
156 .enter = &intel_idle },
157 { /* MWAIT C5 */ },
158 { /* MWAIT C6 */
159 .name = "ATM-C6",
160 .desc = "MWAIT 0x40",
161 .driver_data = (void *) 0x40,
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400162 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
Len Brown26717172010-03-08 14:07:30 -0500163 .exit_latency = 200,
164 .power_usage = 150,
165 .target_residency = 800,
166 .enter = NULL }, /* disabled */
167};
168
Len Brown26717172010-03-08 14:07:30 -0500169/**
170 * intel_idle
171 * @dev: cpuidle_device
172 * @state: cpuidle state
173 *
174 */
175static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
176{
177 unsigned long ecx = 1; /* break on interrupt flag */
178 unsigned long eax = (unsigned long)cpuidle_get_statedata(state);
179 unsigned int cstate;
180 ktime_t kt_before, kt_after;
181 s64 usec_delta;
182 int cpu = smp_processor_id();
183
184 cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
185
Len Brown26717172010-03-08 14:07:30 -0500186 local_irq_disable();
187
Suresh Siddha6110a1f2010-09-30 21:19:07 -0400188 /*
189 * If the state flag indicates that the TLB will be flushed or if this
190 * is the deepest c-state supported, do a voluntary leave mm to avoid
191 * costly and mostly unnecessary wakeups for flushing the user TLB's
192 * associated with the active mm.
193 */
194 if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED ||
195 (&dev->states[dev->state_count - 1] == state))
196 leave_mm(cpu);
197
Len Brown26717172010-03-08 14:07:30 -0500198 if (!(lapic_timer_reliable_states & (1 << (cstate))))
199 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
200
201 kt_before = ktime_get_real();
202
203 stop_critical_timings();
204#ifndef MODULE
Linus Torvalds8d915302010-08-04 11:13:36 -0700205 trace_power_start(POWER_CSTATE, (eax >> 4) + 1, cpu);
Len Brown26717172010-03-08 14:07:30 -0500206#endif
207 if (!need_resched()) {
208
209 __monitor((void *)&current_thread_info()->flags, 0, 0);
210 smp_mb();
211 if (!need_resched())
212 __mwait(eax, ecx);
213 }
214
215 start_critical_timings();
216
217 kt_after = ktime_get_real();
218 usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
219
220 local_irq_enable();
221
222 if (!(lapic_timer_reliable_states & (1 << (cstate))))
223 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
224
225 return usec_delta;
226}
227
228/*
229 * intel_idle_probe()
230 */
231static int intel_idle_probe(void)
232{
Len Brownc4236282010-05-28 02:22:03 -0400233 unsigned int eax, ebx, ecx;
Len Brown26717172010-03-08 14:07:30 -0500234
235 if (max_cstate == 0) {
236 pr_debug(PREFIX "disabled\n");
237 return -EPERM;
238 }
239
240 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
241 return -ENODEV;
242
243 if (!boot_cpu_has(X86_FEATURE_MWAIT))
244 return -ENODEV;
245
246 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
247 return -ENODEV;
248
Len Brownc4236282010-05-28 02:22:03 -0400249 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
Len Brown26717172010-03-08 14:07:30 -0500250
251 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
252 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
253 return -ENODEV;
Len Brown26717172010-03-08 14:07:30 -0500254
Len Brownc4236282010-05-28 02:22:03 -0400255 pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
Len Brown26717172010-03-08 14:07:30 -0500256
257 if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
258 lapic_timer_reliable_states = 0xFFFFFFFF;
259
260 if (boot_cpu_data.x86 != 6) /* family 6 */
261 return -ENODEV;
262
263 switch (boot_cpu_data.x86_model) {
264
265 case 0x1A: /* Core i7, Xeon 5500 series */
266 case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */
267 case 0x1F: /* Core i7 and i5 Processor - Nehalem */
268 case 0x2E: /* Nehalem-EX Xeon */
Len Brownec67a2b2010-07-26 23:40:19 -0400269 case 0x2F: /* Westmere-EX Xeon */
Len Brown26717172010-03-08 14:07:30 -0500270 lapic_timer_reliable_states = (1 << 1); /* C1 */
271
272 case 0x25: /* Westmere */
273 case 0x2C: /* Westmere */
274 cpuidle_state_table = nehalem_cstates;
Len Brown26717172010-03-08 14:07:30 -0500275 break;
276
277 case 0x1C: /* 28 - Atom Processor */
Arjan van de Ven4725fd32010-07-21 23:42:25 -0400278 case 0x26: /* 38 - Lincroft Atom Processor */
Len Brown26717172010-03-08 14:07:30 -0500279 lapic_timer_reliable_states = (1 << 2) | (1 << 1); /* C2, C1 */
280 cpuidle_state_table = atom_cstates;
Len Brown26717172010-03-08 14:07:30 -0500281 break;
282#ifdef FUTURE_USE
283 case 0x17: /* 23 - Core 2 Duo */
284 lapic_timer_reliable_states = (1 << 2) | (1 << 1); /* C2, C1 */
285#endif
286
287 default:
288 pr_debug(PREFIX "does not run on family %d model %d\n",
289 boot_cpu_data.x86, boot_cpu_data.x86_model);
290 return -ENODEV;
291 }
292
293 pr_debug(PREFIX "v" INTEL_IDLE_VERSION
294 " model 0x%X\n", boot_cpu_data.x86_model);
295
296 pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
297 lapic_timer_reliable_states);
298 return 0;
299}
300
301/*
302 * intel_idle_cpuidle_devices_uninit()
303 * unregister, free cpuidle_devices
304 */
305static void intel_idle_cpuidle_devices_uninit(void)
306{
307 int i;
308 struct cpuidle_device *dev;
309
310 for_each_online_cpu(i) {
311 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
312 cpuidle_unregister_device(dev);
313 }
314
315 free_percpu(intel_idle_cpuidle_devices);
316 return;
317}
318/*
319 * intel_idle_cpuidle_devices_init()
320 * allocate, initialize, register cpuidle_devices
321 */
322static int intel_idle_cpuidle_devices_init(void)
323{
324 int i, cstate;
325 struct cpuidle_device *dev;
326
327 intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
328 if (intel_idle_cpuidle_devices == NULL)
329 return -ENOMEM;
330
331 for_each_online_cpu(i) {
332 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
333
334 dev->state_count = 1;
335
336 for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
337 int num_substates;
338
339 if (cstate > max_cstate) {
340 printk(PREFIX "max_cstate %d reached\n",
341 max_cstate);
342 break;
343 }
344
345 /* does the state exist in CPUID.MWAIT? */
Len Brownc4236282010-05-28 02:22:03 -0400346 num_substates = (mwait_substates >> ((cstate) * 4))
Len Brown26717172010-03-08 14:07:30 -0500347 & MWAIT_SUBSTATE_MASK;
348 if (num_substates == 0)
349 continue;
350 /* is the state not enabled? */
351 if (cpuidle_state_table[cstate].enter == NULL) {
352 /* does the driver not know about the state? */
353 if (*cpuidle_state_table[cstate].name == '\0')
354 pr_debug(PREFIX "unaware of model 0x%x"
355 " MWAIT %d please"
356 " contact lenb@kernel.org",
357 boot_cpu_data.x86_model, cstate);
358 continue;
359 }
360
361 if ((cstate > 2) &&
362 !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
363 mark_tsc_unstable("TSC halts in idle"
364 " states deeper than C2");
365
366 dev->states[dev->state_count] = /* structure copy */
367 cpuidle_state_table[cstate];
368
369 dev->state_count += 1;
370 }
371
372 dev->cpu = i;
373 if (cpuidle_register_device(dev)) {
374 pr_debug(PREFIX "cpuidle_register_device %d failed!\n",
375 i);
376 intel_idle_cpuidle_devices_uninit();
377 return -EIO;
378 }
379 }
380
381 return 0;
382}
383
384
385static int __init intel_idle_init(void)
386{
387 int retval;
388
389 retval = intel_idle_probe();
390 if (retval)
391 return retval;
392
393 retval = cpuidle_register_driver(&intel_idle_driver);
394 if (retval) {
395 printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
396 cpuidle_get_driver()->name);
397 return retval;
398 }
399
400 retval = intel_idle_cpuidle_devices_init();
401 if (retval) {
402 cpuidle_unregister_driver(&intel_idle_driver);
403 return retval;
404 }
405
406 return 0;
407}
408
409static void __exit intel_idle_exit(void)
410{
411 intel_idle_cpuidle_devices_uninit();
412 cpuidle_unregister_driver(&intel_idle_driver);
413
414 return;
415}
416
417module_init(intel_idle_init);
418module_exit(intel_idle_exit);
419
Len Brown26717172010-03-08 14:07:30 -0500420module_param(max_cstate, int, 0444);
Len Brown26717172010-03-08 14:07:30 -0500421
422MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
423MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
424MODULE_LICENSE("GPL");