Merge remote-tracking branch 'moduleh/module.h-split'
[linux-2.6/next.git] / drivers / idle / intel_idle.c
blob18767f8ab090a409c512db7ba29bf4b8d56cb2f2
1 /*
2 * intel_idle.c - native hardware idle loop for modern Intel processors
4 * Copyright (c) 2010, Intel Corporation.
5 * Len Brown <len.brown@intel.com>
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.
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.
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.
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.
29 * Design Assumptions
31 * All CPUs have same idle states as boot CPU
33 * Chipset BM_STS (bus master status) bit is a NOP
34 * for preventing entry into deep C-stats
38 * Known limitations
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.
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.
49 * There is currently no kernel-based automatic probing/loading mechanism
50 * if the driver is built as a module.
53 /* un-comment DEBUG to enable pr_debug() statements */
54 #define DEBUG
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 #include <linux/notifier.h>
63 #include <linux/cpu.h>
64 #include <linux/module.h>
65 #include <asm/mwait.h>
66 #include <asm/msr.h>
68 #define INTEL_IDLE_VERSION "0.4"
69 #define PREFIX "intel_idle: "
71 static struct cpuidle_driver intel_idle_driver = {
72 .name = "intel_idle",
73 .owner = THIS_MODULE,
75 /* intel_idle.max_cstate=0 disables driver */
76 static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
78 static unsigned int mwait_substates;
80 #define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
81 /* Reliable LAPIC Timer States, bit 1 for C1 etc. */
82 static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */
84 static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
85 static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state);
87 static struct cpuidle_state *cpuidle_state_table;
90 * Hardware C-state auto-demotion may not always be optimal.
91 * Indicate which enable bits to clear here.
93 static unsigned long long auto_demotion_disable_flags;
96 * Set this flag for states where the HW flushes the TLB for us
97 * and so we don't need cross-calls to keep it consistent.
98 * If this flag is set, SW flushes the TLB, so even if the
99 * HW doesn't do the flushing, this flag is safe to use.
101 #define CPUIDLE_FLAG_TLB_FLUSHED 0x10000
104 * States are indexed by the cstate number,
105 * which is also the index into the MWAIT hint array.
106 * Thus C0 is a dummy.
108 static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
109 { /* MWAIT C0 */ },
110 { /* MWAIT C1 */
111 .name = "C1-NHM",
112 .desc = "MWAIT 0x00",
113 .driver_data = (void *) 0x00,
114 .flags = CPUIDLE_FLAG_TIME_VALID,
115 .exit_latency = 3,
116 .target_residency = 6,
117 .enter = &intel_idle },
118 { /* MWAIT C2 */
119 .name = "C3-NHM",
120 .desc = "MWAIT 0x10",
121 .driver_data = (void *) 0x10,
122 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
123 .exit_latency = 20,
124 .target_residency = 80,
125 .enter = &intel_idle },
126 { /* MWAIT C3 */
127 .name = "C6-NHM",
128 .desc = "MWAIT 0x20",
129 .driver_data = (void *) 0x20,
130 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
131 .exit_latency = 200,
132 .target_residency = 800,
133 .enter = &intel_idle },
136 static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
137 { /* MWAIT C0 */ },
138 { /* MWAIT C1 */
139 .name = "C1-SNB",
140 .desc = "MWAIT 0x00",
141 .driver_data = (void *) 0x00,
142 .flags = CPUIDLE_FLAG_TIME_VALID,
143 .exit_latency = 1,
144 .target_residency = 1,
145 .enter = &intel_idle },
146 { /* MWAIT C2 */
147 .name = "C3-SNB",
148 .desc = "MWAIT 0x10",
149 .driver_data = (void *) 0x10,
150 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
151 .exit_latency = 80,
152 .target_residency = 211,
153 .enter = &intel_idle },
154 { /* MWAIT C3 */
155 .name = "C6-SNB",
156 .desc = "MWAIT 0x20",
157 .driver_data = (void *) 0x20,
158 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
159 .exit_latency = 104,
160 .target_residency = 345,
161 .enter = &intel_idle },
162 { /* MWAIT C4 */
163 .name = "C7-SNB",
164 .desc = "MWAIT 0x30",
165 .driver_data = (void *) 0x30,
166 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
167 .exit_latency = 109,
168 .target_residency = 345,
169 .enter = &intel_idle },
172 static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
173 { /* MWAIT C0 */ },
174 { /* MWAIT C1 */
175 .name = "C1-ATM",
176 .desc = "MWAIT 0x00",
177 .driver_data = (void *) 0x00,
178 .flags = CPUIDLE_FLAG_TIME_VALID,
179 .exit_latency = 1,
180 .target_residency = 4,
181 .enter = &intel_idle },
182 { /* MWAIT C2 */
183 .name = "C2-ATM",
184 .desc = "MWAIT 0x10",
185 .driver_data = (void *) 0x10,
186 .flags = CPUIDLE_FLAG_TIME_VALID,
187 .exit_latency = 20,
188 .target_residency = 80,
189 .enter = &intel_idle },
190 { /* MWAIT C3 */ },
191 { /* MWAIT C4 */
192 .name = "C4-ATM",
193 .desc = "MWAIT 0x30",
194 .driver_data = (void *) 0x30,
195 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
196 .exit_latency = 100,
197 .target_residency = 400,
198 .enter = &intel_idle },
199 { /* MWAIT C5 */ },
200 { /* MWAIT C6 */
201 .name = "C6-ATM",
202 .desc = "MWAIT 0x52",
203 .driver_data = (void *) 0x52,
204 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
205 .exit_latency = 140,
206 .target_residency = 560,
207 .enter = &intel_idle },
211 * intel_idle
212 * @dev: cpuidle_device
213 * @state: cpuidle state
216 static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
218 unsigned long ecx = 1; /* break on interrupt flag */
219 unsigned long eax = (unsigned long)cpuidle_get_statedata(state);
220 unsigned int cstate;
221 ktime_t kt_before, kt_after;
222 s64 usec_delta;
223 int cpu = smp_processor_id();
225 cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
227 local_irq_disable();
230 * leave_mm() to avoid costly and often unnecessary wakeups
231 * for flushing the user TLB's associated with the active mm.
233 if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
234 leave_mm(cpu);
236 if (!(lapic_timer_reliable_states & (1 << (cstate))))
237 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
239 kt_before = ktime_get_real();
241 stop_critical_timings();
242 if (!need_resched()) {
244 __monitor((void *)&current_thread_info()->flags, 0, 0);
245 smp_mb();
246 if (!need_resched())
247 __mwait(eax, ecx);
250 start_critical_timings();
252 kt_after = ktime_get_real();
253 usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
255 local_irq_enable();
257 if (!(lapic_timer_reliable_states & (1 << (cstate))))
258 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
260 return usec_delta;
263 static void __setup_broadcast_timer(void *arg)
265 unsigned long reason = (unsigned long)arg;
266 int cpu = smp_processor_id();
268 reason = reason ?
269 CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
271 clockevents_notify(reason, &cpu);
274 static int setup_broadcast_cpuhp_notify(struct notifier_block *n,
275 unsigned long action, void *hcpu)
277 int hotcpu = (unsigned long)hcpu;
279 switch (action & 0xf) {
280 case CPU_ONLINE:
281 smp_call_function_single(hotcpu, __setup_broadcast_timer,
282 (void *)true, 1);
283 break;
285 return NOTIFY_OK;
288 static struct notifier_block setup_broadcast_notifier = {
289 .notifier_call = setup_broadcast_cpuhp_notify,
292 static void auto_demotion_disable(void *dummy)
294 unsigned long long msr_bits;
296 rdmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
297 msr_bits &= ~auto_demotion_disable_flags;
298 wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
302 * intel_idle_probe()
304 static int intel_idle_probe(void)
306 unsigned int eax, ebx, ecx;
308 if (max_cstate == 0) {
309 pr_debug(PREFIX "disabled\n");
310 return -EPERM;
313 if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
314 return -ENODEV;
316 if (!boot_cpu_has(X86_FEATURE_MWAIT))
317 return -ENODEV;
319 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
320 return -ENODEV;
322 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
324 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
325 !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
326 return -ENODEV;
328 pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
331 if (boot_cpu_data.x86 != 6) /* family 6 */
332 return -ENODEV;
334 switch (boot_cpu_data.x86_model) {
336 case 0x1A: /* Core i7, Xeon 5500 series */
337 case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */
338 case 0x1F: /* Core i7 and i5 Processor - Nehalem */
339 case 0x2E: /* Nehalem-EX Xeon */
340 case 0x2F: /* Westmere-EX Xeon */
341 case 0x25: /* Westmere */
342 case 0x2C: /* Westmere */
343 cpuidle_state_table = nehalem_cstates;
344 auto_demotion_disable_flags =
345 (NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE);
346 break;
348 case 0x1C: /* 28 - Atom Processor */
349 cpuidle_state_table = atom_cstates;
350 break;
352 case 0x26: /* 38 - Lincroft Atom Processor */
353 cpuidle_state_table = atom_cstates;
354 auto_demotion_disable_flags = ATM_LNC_C6_AUTO_DEMOTE;
355 break;
357 case 0x2A: /* SNB */
358 case 0x2D: /* SNB Xeon */
359 cpuidle_state_table = snb_cstates;
360 break;
362 default:
363 pr_debug(PREFIX "does not run on family %d model %d\n",
364 boot_cpu_data.x86, boot_cpu_data.x86_model);
365 return -ENODEV;
368 if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
369 lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
370 else {
371 smp_call_function(__setup_broadcast_timer, (void *)true, 1);
372 register_cpu_notifier(&setup_broadcast_notifier);
375 pr_debug(PREFIX "v" INTEL_IDLE_VERSION
376 " model 0x%X\n", boot_cpu_data.x86_model);
378 pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
379 lapic_timer_reliable_states);
380 return 0;
384 * intel_idle_cpuidle_devices_uninit()
385 * unregister, free cpuidle_devices
387 static void intel_idle_cpuidle_devices_uninit(void)
389 int i;
390 struct cpuidle_device *dev;
392 for_each_online_cpu(i) {
393 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
394 cpuidle_unregister_device(dev);
397 free_percpu(intel_idle_cpuidle_devices);
398 return;
401 * intel_idle_cpuidle_devices_init()
402 * allocate, initialize, register cpuidle_devices
404 static int intel_idle_cpuidle_devices_init(void)
406 int i, cstate;
407 struct cpuidle_device *dev;
409 intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
410 if (intel_idle_cpuidle_devices == NULL)
411 return -ENOMEM;
413 for_each_online_cpu(i) {
414 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
416 dev->state_count = 1;
418 for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
419 int num_substates;
421 if (cstate > max_cstate) {
422 printk(PREFIX "max_cstate %d reached\n",
423 max_cstate);
424 break;
427 /* does the state exist in CPUID.MWAIT? */
428 num_substates = (mwait_substates >> ((cstate) * 4))
429 & MWAIT_SUBSTATE_MASK;
430 if (num_substates == 0)
431 continue;
432 /* is the state not enabled? */
433 if (cpuidle_state_table[cstate].enter == NULL) {
434 /* does the driver not know about the state? */
435 if (*cpuidle_state_table[cstate].name == '\0')
436 pr_debug(PREFIX "unaware of model 0x%x"
437 " MWAIT %d please"
438 " contact lenb@kernel.org",
439 boot_cpu_data.x86_model, cstate);
440 continue;
443 if ((cstate > 2) &&
444 !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
445 mark_tsc_unstable("TSC halts in idle"
446 " states deeper than C2");
448 dev->states[dev->state_count] = /* structure copy */
449 cpuidle_state_table[cstate];
451 dev->state_count += 1;
454 dev->cpu = i;
455 if (cpuidle_register_device(dev)) {
456 pr_debug(PREFIX "cpuidle_register_device %d failed!\n",
458 intel_idle_cpuidle_devices_uninit();
459 return -EIO;
462 if (auto_demotion_disable_flags)
463 smp_call_function(auto_demotion_disable, NULL, 1);
465 return 0;
469 static int __init intel_idle_init(void)
471 int retval;
473 /* Do not load intel_idle at all for now if idle= is passed */
474 if (boot_option_idle_override != IDLE_NO_OVERRIDE)
475 return -ENODEV;
477 retval = intel_idle_probe();
478 if (retval)
479 return retval;
481 retval = cpuidle_register_driver(&intel_idle_driver);
482 if (retval) {
483 printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
484 cpuidle_get_driver()->name);
485 return retval;
488 retval = intel_idle_cpuidle_devices_init();
489 if (retval) {
490 cpuidle_unregister_driver(&intel_idle_driver);
491 return retval;
494 return 0;
497 static void __exit intel_idle_exit(void)
499 intel_idle_cpuidle_devices_uninit();
500 cpuidle_unregister_driver(&intel_idle_driver);
502 if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE) {
503 smp_call_function(__setup_broadcast_timer, (void *)false, 1);
504 unregister_cpu_notifier(&setup_broadcast_notifier);
507 return;
510 module_init(intel_idle_init);
511 module_exit(intel_idle_exit);
513 module_param(max_cstate, int, 0444);
515 MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
516 MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
517 MODULE_LICENSE("GPL");