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
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.
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
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 */
56 #include <linux/kernel.h>
57 #include <linux/cpuidle.h>
58 #include <linux/clockchips.h>
59 #include <trace/events/power.h>
60 #include <linux/sched.h>
61 #include <linux/notifier.h>
62 #include <linux/cpu.h>
63 #include <linux/module.h>
64 #include <asm/cpu_device_id.h>
65 #include <asm/mwait.h>
68 #define INTEL_IDLE_VERSION "0.4"
69 #define PREFIX "intel_idle: "
71 static struct cpuidle_driver intel_idle_driver = {
74 .en_core_tk_irqen = 1,
76 /* intel_idle.max_cstate=0 disables driver */
77 static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
79 static unsigned int mwait_substates;
81 #define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
82 /* Reliable LAPIC Timer States, bit 1 for C1 etc. */
83 static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */
86 struct cpuidle_state *state_table;
89 * Hardware C-state auto-demotion may not always be optimal.
90 * Indicate which enable bits to clear here.
92 unsigned long auto_demotion_disable_flags;
95 static const struct idle_cpu *icpu;
96 static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
97 static int intel_idle(struct cpuidle_device *dev,
98 struct cpuidle_driver *drv, int index);
99 static int intel_idle_cpu_init(int cpu);
101 static struct cpuidle_state *cpuidle_state_table;
104 * Set this flag for states where the HW flushes the TLB for us
105 * and so we don't need cross-calls to keep it consistent.
106 * If this flag is set, SW flushes the TLB, so even if the
107 * HW doesn't do the flushing, this flag is safe to use.
109 #define CPUIDLE_FLAG_TLB_FLUSHED 0x10000
112 * States are indexed by the cstate number,
113 * which is also the index into the MWAIT hint array.
114 * Thus C0 is a dummy.
116 static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
120 .desc = "MWAIT 0x00",
121 .flags = CPUIDLE_FLAG_TIME_VALID,
123 .target_residency = 6,
124 .enter = &intel_idle },
127 .desc = "MWAIT 0x10",
128 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
130 .target_residency = 80,
131 .enter = &intel_idle },
134 .desc = "MWAIT 0x20",
135 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
137 .target_residency = 800,
138 .enter = &intel_idle },
141 static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
145 .desc = "MWAIT 0x00",
146 .flags = CPUIDLE_FLAG_TIME_VALID,
148 .target_residency = 1,
149 .enter = &intel_idle },
152 .desc = "MWAIT 0x10",
153 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
155 .target_residency = 211,
156 .enter = &intel_idle },
159 .desc = "MWAIT 0x20",
160 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
162 .target_residency = 345,
163 .enter = &intel_idle },
166 .desc = "MWAIT 0x30",
167 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
169 .target_residency = 345,
170 .enter = &intel_idle },
173 static struct cpuidle_state ivb_cstates[MWAIT_MAX_NUM_CSTATES] = {
177 .desc = "MWAIT 0x00",
178 .flags = CPUIDLE_FLAG_TIME_VALID,
180 .target_residency = 1,
181 .enter = &intel_idle },
184 .desc = "MWAIT 0x10",
185 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
187 .target_residency = 156,
188 .enter = &intel_idle },
191 .desc = "MWAIT 0x20",
192 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
194 .target_residency = 300,
195 .enter = &intel_idle },
198 .desc = "MWAIT 0x30",
199 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
201 .target_residency = 300,
202 .enter = &intel_idle },
205 static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
209 .desc = "MWAIT 0x00",
210 .flags = CPUIDLE_FLAG_TIME_VALID,
212 .target_residency = 4,
213 .enter = &intel_idle },
216 .desc = "MWAIT 0x10",
217 .flags = CPUIDLE_FLAG_TIME_VALID,
219 .target_residency = 80,
220 .enter = &intel_idle },
224 .desc = "MWAIT 0x30",
225 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
227 .target_residency = 400,
228 .enter = &intel_idle },
232 .desc = "MWAIT 0x52",
233 .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
235 .target_residency = 560,
236 .enter = &intel_idle },
239 static long get_driver_data(int cstate)
244 case 1: /* MWAIT C1 */
247 case 2: /* MWAIT C2 */
250 case 3: /* MWAIT C3 */
253 case 4: /* MWAIT C4 */
256 case 5: /* MWAIT C5 */
259 case 6: /* MWAIT C6 */
270 * @dev: cpuidle_device
271 * @drv: cpuidle driver
272 * @index: index of cpuidle state
274 * Must be called under local_irq_disable().
276 static int intel_idle(struct cpuidle_device *dev,
277 struct cpuidle_driver *drv, int index)
279 unsigned long ecx = 1; /* break on interrupt flag */
280 struct cpuidle_state *state = &drv->states[index];
281 struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
282 unsigned long eax = (unsigned long)cpuidle_get_statedata(state_usage);
284 int cpu = smp_processor_id();
286 cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
289 * leave_mm() to avoid costly and often unnecessary wakeups
290 * for flushing the user TLB's associated with the active mm.
292 if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
295 if (!(lapic_timer_reliable_states & (1 << (cstate))))
296 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
298 stop_critical_timings();
299 if (!need_resched()) {
301 __monitor((void *)¤t_thread_info()->flags, 0, 0);
307 start_critical_timings();
309 if (!(lapic_timer_reliable_states & (1 << (cstate))))
310 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
315 static void __setup_broadcast_timer(void *arg)
317 unsigned long reason = (unsigned long)arg;
318 int cpu = smp_processor_id();
321 CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
323 clockevents_notify(reason, &cpu);
326 static int cpu_hotplug_notify(struct notifier_block *n,
327 unsigned long action, void *hcpu)
329 int hotcpu = (unsigned long)hcpu;
330 struct cpuidle_device *dev;
332 switch (action & 0xf) {
335 if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
336 smp_call_function_single(hotcpu, __setup_broadcast_timer,
340 * Some systems can hotplug a cpu at runtime after
341 * the kernel has booted, we have to initialize the
342 * driver in this case
344 dev = per_cpu_ptr(intel_idle_cpuidle_devices, hotcpu);
345 if (!dev->registered)
346 intel_idle_cpu_init(hotcpu);
353 static struct notifier_block cpu_hotplug_notifier = {
354 .notifier_call = cpu_hotplug_notify,
357 static void auto_demotion_disable(void *dummy)
359 unsigned long long msr_bits;
361 rdmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
362 msr_bits &= ~(icpu->auto_demotion_disable_flags);
363 wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
366 static const struct idle_cpu idle_cpu_nehalem = {
367 .state_table = nehalem_cstates,
368 .auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,
371 static const struct idle_cpu idle_cpu_atom = {
372 .state_table = atom_cstates,
375 static const struct idle_cpu idle_cpu_lincroft = {
376 .state_table = atom_cstates,
377 .auto_demotion_disable_flags = ATM_LNC_C6_AUTO_DEMOTE,
380 static const struct idle_cpu idle_cpu_snb = {
381 .state_table = snb_cstates,
384 static const struct idle_cpu idle_cpu_ivb = {
385 .state_table = ivb_cstates,
388 #define ICPU(model, cpu) \
389 { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT, (unsigned long)&cpu }
391 static const struct x86_cpu_id intel_idle_ids[] = {
392 ICPU(0x1a, idle_cpu_nehalem),
393 ICPU(0x1e, idle_cpu_nehalem),
394 ICPU(0x1f, idle_cpu_nehalem),
395 ICPU(0x25, idle_cpu_nehalem),
396 ICPU(0x2c, idle_cpu_nehalem),
397 ICPU(0x2e, idle_cpu_nehalem),
398 ICPU(0x1c, idle_cpu_atom),
399 ICPU(0x26, idle_cpu_lincroft),
400 ICPU(0x2f, idle_cpu_nehalem),
401 ICPU(0x2a, idle_cpu_snb),
402 ICPU(0x2d, idle_cpu_snb),
403 ICPU(0x3a, idle_cpu_ivb),
404 ICPU(0x3e, idle_cpu_ivb),
407 MODULE_DEVICE_TABLE(x86cpu, intel_idle_ids);
412 static int intel_idle_probe(void)
414 unsigned int eax, ebx, ecx;
415 const struct x86_cpu_id *id;
417 if (max_cstate == 0) {
418 pr_debug(PREFIX "disabled\n");
422 id = x86_match_cpu(intel_idle_ids);
424 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
425 boot_cpu_data.x86 == 6)
426 pr_debug(PREFIX "does not run on family %d model %d\n",
427 boot_cpu_data.x86, boot_cpu_data.x86_model);
431 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
434 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
436 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
437 !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
441 pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
443 icpu = (const struct idle_cpu *)id->driver_data;
444 cpuidle_state_table = icpu->state_table;
446 if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
447 lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
449 on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
451 register_cpu_notifier(&cpu_hotplug_notifier);
453 pr_debug(PREFIX "v" INTEL_IDLE_VERSION
454 " model 0x%X\n", boot_cpu_data.x86_model);
456 pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
457 lapic_timer_reliable_states);
462 * intel_idle_cpuidle_devices_uninit()
463 * unregister, free cpuidle_devices
465 static void intel_idle_cpuidle_devices_uninit(void)
468 struct cpuidle_device *dev;
470 for_each_online_cpu(i) {
471 dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
472 cpuidle_unregister_device(dev);
475 free_percpu(intel_idle_cpuidle_devices);
479 * intel_idle_cpuidle_driver_init()
480 * allocate, initialize cpuidle_states
482 static int intel_idle_cpuidle_driver_init(void)
485 struct cpuidle_driver *drv = &intel_idle_driver;
487 drv->state_count = 1;
489 for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
492 if (cstate > max_cstate) {
493 printk(PREFIX "max_cstate %d reached\n",
498 /* does the state exist in CPUID.MWAIT? */
499 num_substates = (mwait_substates >> ((cstate) * 4))
500 & MWAIT_SUBSTATE_MASK;
501 if (num_substates == 0)
503 /* is the state not enabled? */
504 if (cpuidle_state_table[cstate].enter == NULL) {
505 /* does the driver not know about the state? */
506 if (*cpuidle_state_table[cstate].name == '\0')
507 pr_debug(PREFIX "unaware of model 0x%x"
509 " contact lenb@kernel.org",
510 boot_cpu_data.x86_model, cstate);
515 !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
516 mark_tsc_unstable("TSC halts in idle"
517 " states deeper than C2");
519 drv->states[drv->state_count] = /* structure copy */
520 cpuidle_state_table[cstate];
522 drv->state_count += 1;
525 if (icpu->auto_demotion_disable_flags)
526 on_each_cpu(auto_demotion_disable, NULL, 1);
533 * intel_idle_cpu_init()
534 * allocate, initialize, register cpuidle_devices
535 * @cpu: cpu/core to initialize
537 static int intel_idle_cpu_init(int cpu)
540 struct cpuidle_device *dev;
542 dev = per_cpu_ptr(intel_idle_cpuidle_devices, cpu);
544 dev->state_count = 1;
546 for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
549 if (cstate > max_cstate) {
550 printk(PREFIX "max_cstate %d reached\n", max_cstate);
554 /* does the state exist in CPUID.MWAIT? */
555 num_substates = (mwait_substates >> ((cstate) * 4))
556 & MWAIT_SUBSTATE_MASK;
557 if (num_substates == 0)
559 /* is the state not enabled? */
560 if (cpuidle_state_table[cstate].enter == NULL)
563 dev->states_usage[dev->state_count].driver_data =
564 (void *)get_driver_data(cstate);
566 dev->state_count += 1;
571 if (cpuidle_register_device(dev)) {
572 pr_debug(PREFIX "cpuidle_register_device %d failed!\n", cpu);
573 intel_idle_cpuidle_devices_uninit();
577 if (icpu->auto_demotion_disable_flags)
578 smp_call_function_single(cpu, auto_demotion_disable, NULL, 1);
583 static int __init intel_idle_init(void)
587 /* Do not load intel_idle at all for now if idle= is passed */
588 if (boot_option_idle_override != IDLE_NO_OVERRIDE)
591 retval = intel_idle_probe();
595 intel_idle_cpuidle_driver_init();
596 retval = cpuidle_register_driver(&intel_idle_driver);
598 struct cpuidle_driver *drv = cpuidle_get_driver();
599 printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
600 drv ? drv->name : "none");
604 intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
605 if (intel_idle_cpuidle_devices == NULL)
608 for_each_online_cpu(i) {
609 retval = intel_idle_cpu_init(i);
611 cpuidle_unregister_driver(&intel_idle_driver);
619 static void __exit intel_idle_exit(void)
621 intel_idle_cpuidle_devices_uninit();
622 cpuidle_unregister_driver(&intel_idle_driver);
625 if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
626 on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
627 unregister_cpu_notifier(&cpu_hotplug_notifier);
632 module_init(intel_idle_init);
633 module_exit(intel_idle_exit);
635 module_param(max_cstate, int, 0444);
637 MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
638 MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
639 MODULE_LICENSE("GPL");