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 <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>
68 #define INTEL_IDLE_VERSION "0.4"
69 #define PREFIX "intel_idle: "
71 static struct cpuidle_driver intel_idle_driver
= {
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
] = {
112 .desc
= "MWAIT 0x00",
113 .driver_data
= (void *) 0x00,
114 .flags
= CPUIDLE_FLAG_TIME_VALID
,
116 .target_residency
= 6,
117 .enter
= &intel_idle
},
120 .desc
= "MWAIT 0x10",
121 .driver_data
= (void *) 0x10,
122 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
124 .target_residency
= 80,
125 .enter
= &intel_idle
},
128 .desc
= "MWAIT 0x20",
129 .driver_data
= (void *) 0x20,
130 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
132 .target_residency
= 800,
133 .enter
= &intel_idle
},
136 static struct cpuidle_state snb_cstates
[MWAIT_MAX_NUM_CSTATES
] = {
140 .desc
= "MWAIT 0x00",
141 .driver_data
= (void *) 0x00,
142 .flags
= CPUIDLE_FLAG_TIME_VALID
,
144 .target_residency
= 1,
145 .enter
= &intel_idle
},
148 .desc
= "MWAIT 0x10",
149 .driver_data
= (void *) 0x10,
150 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
152 .target_residency
= 211,
153 .enter
= &intel_idle
},
156 .desc
= "MWAIT 0x20",
157 .driver_data
= (void *) 0x20,
158 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
160 .target_residency
= 345,
161 .enter
= &intel_idle
},
164 .desc
= "MWAIT 0x30",
165 .driver_data
= (void *) 0x30,
166 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
168 .target_residency
= 345,
169 .enter
= &intel_idle
},
172 static struct cpuidle_state atom_cstates
[MWAIT_MAX_NUM_CSTATES
] = {
176 .desc
= "MWAIT 0x00",
177 .driver_data
= (void *) 0x00,
178 .flags
= CPUIDLE_FLAG_TIME_VALID
,
180 .target_residency
= 4,
181 .enter
= &intel_idle
},
184 .desc
= "MWAIT 0x10",
185 .driver_data
= (void *) 0x10,
186 .flags
= CPUIDLE_FLAG_TIME_VALID
,
188 .target_residency
= 80,
189 .enter
= &intel_idle
},
193 .desc
= "MWAIT 0x30",
194 .driver_data
= (void *) 0x30,
195 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
197 .target_residency
= 400,
198 .enter
= &intel_idle
},
202 .desc
= "MWAIT 0x52",
203 .driver_data
= (void *) 0x52,
204 .flags
= CPUIDLE_FLAG_TIME_VALID
| CPUIDLE_FLAG_TLB_FLUSHED
,
206 .target_residency
= 560,
207 .enter
= &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
);
221 ktime_t kt_before
, kt_after
;
223 int cpu
= smp_processor_id();
225 cstate
= (((eax
) >> MWAIT_SUBSTATE_SIZE
) & MWAIT_CSTATE_MASK
) + 1;
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
)
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 *)¤t_thread_info()->flags
, 0, 0);
250 start_critical_timings();
252 kt_after
= ktime_get_real();
253 usec_delta
= ktime_to_us(ktime_sub(kt_after
, kt_before
));
257 if (!(lapic_timer_reliable_states
& (1 << (cstate
))))
258 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT
, &cpu
);
263 static void __setup_broadcast_timer(void *arg
)
265 unsigned long reason
= (unsigned long)arg
;
266 int cpu
= smp_processor_id();
269 CLOCK_EVT_NOTIFY_BROADCAST_ON
: CLOCK_EVT_NOTIFY_BROADCAST_OFF
;
271 clockevents_notify(reason
, &cpu
);
274 static void auto_demotion_disable(void *dummy
)
276 unsigned long long msr_bits
;
278 rdmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL
, msr_bits
);
279 msr_bits
&= ~auto_demotion_disable_flags
;
280 wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL
, msr_bits
);
283 static void __intel_idle_notify_handler(void *arg
)
285 if (auto_demotion_disable_flags
)
286 auto_demotion_disable(NULL
);
288 if (lapic_timer_reliable_states
!= LAPIC_TIMER_ALWAYS_RELIABLE
)
289 __setup_broadcast_timer((void *)true);
292 static int setup_intelidle_cpuhp_notify(struct notifier_block
*n
,
293 unsigned long action
, void *hcpu
)
295 int hotcpu
= (unsigned long)hcpu
;
297 switch (action
& 0xf) {
299 smp_call_function_single(hotcpu
, __intel_idle_notify_handler
,
306 static struct notifier_block setup_intelidle_notifier
= {
307 .notifier_call
= setup_intelidle_cpuhp_notify
,
313 static int intel_idle_probe(void)
315 unsigned int eax
, ebx
, ecx
;
317 if (max_cstate
== 0) {
318 pr_debug(PREFIX
"disabled\n");
322 if (boot_cpu_data
.x86_vendor
!= X86_VENDOR_INTEL
)
325 if (!boot_cpu_has(X86_FEATURE_MWAIT
))
328 if (boot_cpu_data
.cpuid_level
< CPUID_MWAIT_LEAF
)
331 cpuid(CPUID_MWAIT_LEAF
, &eax
, &ebx
, &ecx
, &mwait_substates
);
333 if (!(ecx
& CPUID5_ECX_EXTENSIONS_SUPPORTED
) ||
334 !(ecx
& CPUID5_ECX_INTERRUPT_BREAK
))
337 pr_debug(PREFIX
"MWAIT substates: 0x%x\n", mwait_substates
);
340 if (boot_cpu_data
.x86
!= 6) /* family 6 */
343 switch (boot_cpu_data
.x86_model
) {
345 case 0x1A: /* Core i7, Xeon 5500 series */
346 case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */
347 case 0x1F: /* Core i7 and i5 Processor - Nehalem */
348 case 0x2E: /* Nehalem-EX Xeon */
349 case 0x2F: /* Westmere-EX Xeon */
350 case 0x25: /* Westmere */
351 case 0x2C: /* Westmere */
352 cpuidle_state_table
= nehalem_cstates
;
353 auto_demotion_disable_flags
=
354 (NHM_C1_AUTO_DEMOTE
| NHM_C3_AUTO_DEMOTE
);
357 case 0x1C: /* 28 - Atom Processor */
358 cpuidle_state_table
= atom_cstates
;
361 case 0x26: /* 38 - Lincroft Atom Processor */
362 cpuidle_state_table
= atom_cstates
;
363 auto_demotion_disable_flags
= ATM_LNC_C6_AUTO_DEMOTE
;
367 case 0x2D: /* SNB Xeon */
368 cpuidle_state_table
= snb_cstates
;
372 pr_debug(PREFIX
"does not run on family %d model %d\n",
373 boot_cpu_data
.x86
, boot_cpu_data
.x86_model
);
377 if (boot_cpu_has(X86_FEATURE_ARAT
)) /* Always Reliable APIC Timer */
378 lapic_timer_reliable_states
= LAPIC_TIMER_ALWAYS_RELIABLE
;
380 on_each_cpu(__setup_broadcast_timer
, (void *)true, 1);
382 pr_debug(PREFIX
"v" INTEL_IDLE_VERSION
383 " model 0x%X\n", boot_cpu_data
.x86_model
);
385 pr_debug(PREFIX
"lapic_timer_reliable_states 0x%x\n",
386 lapic_timer_reliable_states
);
391 * intel_idle_cpuidle_devices_uninit()
392 * unregister, free cpuidle_devices
394 static void intel_idle_cpuidle_devices_uninit(void)
397 struct cpuidle_device
*dev
;
399 for_each_online_cpu(i
) {
400 dev
= per_cpu_ptr(intel_idle_cpuidle_devices
, i
);
401 cpuidle_unregister_device(dev
);
404 free_percpu(intel_idle_cpuidle_devices
);
408 * intel_idle_cpuidle_devices_init()
409 * allocate, initialize, register cpuidle_devices
411 static int intel_idle_cpuidle_devices_init(void)
414 struct cpuidle_device
*dev
;
416 intel_idle_cpuidle_devices
= alloc_percpu(struct cpuidle_device
);
417 if (intel_idle_cpuidle_devices
== NULL
)
420 for_each_online_cpu(i
) {
421 dev
= per_cpu_ptr(intel_idle_cpuidle_devices
, i
);
423 dev
->state_count
= 1;
425 for (cstate
= 1; cstate
< MWAIT_MAX_NUM_CSTATES
; ++cstate
) {
428 if (cstate
> max_cstate
) {
429 printk(PREFIX
"max_cstate %d reached\n",
434 /* does the state exist in CPUID.MWAIT? */
435 num_substates
= (mwait_substates
>> ((cstate
) * 4))
436 & MWAIT_SUBSTATE_MASK
;
437 if (num_substates
== 0)
439 /* is the state not enabled? */
440 if (cpuidle_state_table
[cstate
].enter
== NULL
) {
441 /* does the driver not know about the state? */
442 if (*cpuidle_state_table
[cstate
].name
== '\0')
443 pr_debug(PREFIX
"unaware of model 0x%x"
445 " contact lenb@kernel.org",
446 boot_cpu_data
.x86_model
, cstate
);
451 !boot_cpu_has(X86_FEATURE_NONSTOP_TSC
))
452 mark_tsc_unstable("TSC halts in idle"
453 " states deeper than C2");
455 dev
->states
[dev
->state_count
] = /* structure copy */
456 cpuidle_state_table
[cstate
];
458 dev
->state_count
+= 1;
462 if (cpuidle_register_device(dev
)) {
463 pr_debug(PREFIX
"cpuidle_register_device %d failed!\n",
465 intel_idle_cpuidle_devices_uninit();
469 if (auto_demotion_disable_flags
)
470 on_each_cpu(auto_demotion_disable
, NULL
, 1);
476 static int __init
intel_idle_init(void)
480 /* Do not load intel_idle at all for now if idle= is passed */
481 if (boot_option_idle_override
!= IDLE_NO_OVERRIDE
)
484 retval
= intel_idle_probe();
488 retval
= cpuidle_register_driver(&intel_idle_driver
);
490 printk(KERN_DEBUG PREFIX
"intel_idle yielding to %s",
491 cpuidle_get_driver()->name
);
495 retval
= intel_idle_cpuidle_devices_init();
497 cpuidle_unregister_driver(&intel_idle_driver
);
501 if (auto_demotion_disable_flags
|| lapic_timer_reliable_states
!=
502 LAPIC_TIMER_ALWAYS_RELIABLE
)
503 register_cpu_notifier(&setup_intelidle_notifier
);
508 static void __exit
intel_idle_exit(void)
510 intel_idle_cpuidle_devices_uninit();
511 cpuidle_unregister_driver(&intel_idle_driver
);
513 if (lapic_timer_reliable_states
!= LAPIC_TIMER_ALWAYS_RELIABLE
)
514 on_each_cpu(__setup_broadcast_timer
, (void *)false, 1);
516 if (auto_demotion_disable_flags
|| lapic_timer_reliable_states
!=
517 LAPIC_TIMER_ALWAYS_RELIABLE
)
518 unregister_cpu_notifier(&setup_intelidle_notifier
);
523 module_init(intel_idle_init
);
524 module_exit(intel_idle_exit
);
526 module_param(max_cstate
, int, 0444);
528 MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
529 MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION
);
530 MODULE_LICENSE("GPL");