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- /*
- * intel_idle.c - native hardware idle loop for modern Intel processors
- *
- * Copyright (c) 2010, Intel Corporation.
- * Len Brown <len.brown@intel.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program; if not, write to the Free Software Foundation, Inc.,
- * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
- */
- /*
- * intel_idle is a cpuidle driver that loads on specific Intel processors
- * in lieu of the legacy ACPI processor_idle driver. The intent is to
- * make Linux more efficient on these processors, as intel_idle knows
- * more than ACPI, as well as make Linux more immune to ACPI BIOS bugs.
- */
- /*
- * Design Assumptions
- *
- * All CPUs have same idle states as boot CPU
- *
- * Chipset BM_STS (bus master status) bit is a NOP
- * for preventing entry into deep C-stats
- */
- /*
- * Known limitations
- *
- * The driver currently initializes for_each_online_cpu() upon modprobe.
- * It it unaware of subsequent processors hot-added to the system.
- * This means that if you boot with maxcpus=n and later online
- * processors above n, those processors will use C1 only.
- *
- * ACPI has a .suspend hack to turn off deep c-statees during suspend
- * to avoid complications with the lapic timer workaround.
- * Have not seen issues with suspend, but may need same workaround here.
- *
- * There is currently no kernel-based automatic probing/loading mechanism
- * if the driver is built as a module.
- */
- /* un-comment DEBUG to enable pr_debug() statements */
- #define DEBUG
- #include <linux/kernel.h>
- #include <linux/cpuidle.h>
- #include <linux/clockchips.h>
- #include <linux/hrtimer.h> /* ktime_get_real() */
- #include <trace/events/power.h>
- #include <linux/sched.h>
- #include <asm/mwait.h>
- #define INTEL_IDLE_VERSION "0.4"
- #define PREFIX "intel_idle: "
- static struct cpuidle_driver intel_idle_driver = {
- .name = "intel_idle",
- .owner = THIS_MODULE,
- };
- /* intel_idle.max_cstate=0 disables driver */
- static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
- static unsigned int mwait_substates;
- /* Reliable LAPIC Timer States, bit 1 for C1 etc. */
- static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */
- static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
- static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state);
- static struct cpuidle_state *cpuidle_state_table;
- /*
- * States are indexed by the cstate number,
- * which is also the index into the MWAIT hint array.
- * Thus C0 is a dummy.
- */
- static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
- { /* MWAIT C0 */ },
- { /* MWAIT C1 */
- .name = "NHM-C1",
- .desc = "MWAIT 0x00",
- .driver_data = (void *) 0x00,
- .flags = CPUIDLE_FLAG_TIME_VALID,
- .exit_latency = 3,
- .target_residency = 6,
- .enter = &intel_idle },
- { /* MWAIT C2 */
- .name = "NHM-C3",
- .desc = "MWAIT 0x10",
- .driver_data = (void *) 0x10,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 20,
- .target_residency = 80,
- .enter = &intel_idle },
- { /* MWAIT C3 */
- .name = "NHM-C6",
- .desc = "MWAIT 0x20",
- .driver_data = (void *) 0x20,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 200,
- .target_residency = 800,
- .enter = &intel_idle },
- };
- static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
- { /* MWAIT C0 */ },
- { /* MWAIT C1 */
- .name = "SNB-C1",
- .desc = "MWAIT 0x00",
- .driver_data = (void *) 0x00,
- .flags = CPUIDLE_FLAG_TIME_VALID,
- .exit_latency = 1,
- .target_residency = 4,
- .enter = &intel_idle },
- { /* MWAIT C2 */
- .name = "SNB-C3",
- .desc = "MWAIT 0x10",
- .driver_data = (void *) 0x10,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 80,
- .target_residency = 160,
- .enter = &intel_idle },
- { /* MWAIT C3 */
- .name = "SNB-C6",
- .desc = "MWAIT 0x20",
- .driver_data = (void *) 0x20,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 104,
- .target_residency = 208,
- .enter = &intel_idle },
- { /* MWAIT C4 */
- .name = "SNB-C7",
- .desc = "MWAIT 0x30",
- .driver_data = (void *) 0x30,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 109,
- .target_residency = 300,
- .enter = &intel_idle },
- };
- static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
- { /* MWAIT C0 */ },
- { /* MWAIT C1 */
- .name = "ATM-C1",
- .desc = "MWAIT 0x00",
- .driver_data = (void *) 0x00,
- .flags = CPUIDLE_FLAG_TIME_VALID,
- .exit_latency = 1,
- .target_residency = 4,
- .enter = &intel_idle },
- { /* MWAIT C2 */
- .name = "ATM-C2",
- .desc = "MWAIT 0x10",
- .driver_data = (void *) 0x10,
- .flags = CPUIDLE_FLAG_TIME_VALID,
- .exit_latency = 20,
- .target_residency = 80,
- .enter = &intel_idle },
- { /* MWAIT C3 */ },
- { /* MWAIT C4 */
- .name = "ATM-C4",
- .desc = "MWAIT 0x30",
- .driver_data = (void *) 0x30,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 100,
- .target_residency = 400,
- .enter = &intel_idle },
- { /* MWAIT C5 */ },
- { /* MWAIT C6 */
- .name = "ATM-C6",
- .desc = "MWAIT 0x52",
- .driver_data = (void *) 0x52,
- .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
- .exit_latency = 140,
- .target_residency = 560,
- .enter = &intel_idle },
- };
- /**
- * intel_idle
- * @dev: cpuidle_device
- * @state: cpuidle state
- *
- */
- static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
- {
- unsigned long ecx = 1; /* break on interrupt flag */
- unsigned long eax = (unsigned long)cpuidle_get_statedata(state);
- unsigned int cstate;
- ktime_t kt_before, kt_after;
- s64 usec_delta;
- int cpu = smp_processor_id();
- cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
- local_irq_disable();
- /*
- * leave_mm() to avoid costly and often unnecessary wakeups
- * for flushing the user TLB's associated with the active mm.
- */
- if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
- leave_mm(cpu);
- if (!(lapic_timer_reliable_states & (1 << (cstate))))
- clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
- kt_before = ktime_get_real();
- stop_critical_timings();
- trace_power_start(POWER_CSTATE, (eax >> 4) + 1, cpu);
- if (!need_resched()) {
- __monitor((void *)¤t_thread_info()->flags, 0, 0);
- smp_mb();
- if (!need_resched())
- __mwait(eax, ecx);
- }
- start_critical_timings();
- kt_after = ktime_get_real();
- usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
- local_irq_enable();
- if (!(lapic_timer_reliable_states & (1 << (cstate))))
- clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
- return usec_delta;
- }
- /*
- * intel_idle_probe()
- */
- static int intel_idle_probe(void)
- {
- unsigned int eax, ebx, ecx;
- if (max_cstate == 0) {
- pr_debug(PREFIX "disabled\n");
- return -EPERM;
- }
- if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
- return -ENODEV;
- if (!boot_cpu_has(X86_FEATURE_MWAIT))
- return -ENODEV;
- if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
- return -ENODEV;
- cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
- if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
- !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
- return -ENODEV;
- pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
- if (boot_cpu_data.x86 != 6) /* family 6 */
- return -ENODEV;
- switch (boot_cpu_data.x86_model) {
- case 0x1A: /* Core i7, Xeon 5500 series */
- case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */
- case 0x1F: /* Core i7 and i5 Processor - Nehalem */
- case 0x2E: /* Nehalem-EX Xeon */
- case 0x2F: /* Westmere-EX Xeon */
- case 0x25: /* Westmere */
- case 0x2C: /* Westmere */
- cpuidle_state_table = nehalem_cstates;
- break;
- case 0x1C: /* 28 - Atom Processor */
- case 0x26: /* 38 - Lincroft Atom Processor */
- cpuidle_state_table = atom_cstates;
- break;
- case 0x2A: /* SNB */
- case 0x2D: /* SNB Xeon */
- cpuidle_state_table = snb_cstates;
- break;
- default:
- pr_debug(PREFIX "does not run on family %d model %d\n",
- boot_cpu_data.x86, boot_cpu_data.x86_model);
- return -ENODEV;
- }
- if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
- lapic_timer_reliable_states = 0xFFFFFFFF;
- pr_debug(PREFIX "v" INTEL_IDLE_VERSION
- " model 0x%X\n", boot_cpu_data.x86_model);
- pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
- lapic_timer_reliable_states);
- return 0;
- }
- /*
- * intel_idle_cpuidle_devices_uninit()
- * unregister, free cpuidle_devices
- */
- static void intel_idle_cpuidle_devices_uninit(void)
- {
- int i;
- struct cpuidle_device *dev;
- for_each_online_cpu(i) {
- dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
- cpuidle_unregister_device(dev);
- }
- free_percpu(intel_idle_cpuidle_devices);
- return;
- }
- /*
- * intel_idle_cpuidle_devices_init()
- * allocate, initialize, register cpuidle_devices
- */
- static int intel_idle_cpuidle_devices_init(void)
- {
- int i, cstate;
- struct cpuidle_device *dev;
- intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
- if (intel_idle_cpuidle_devices == NULL)
- return -ENOMEM;
- for_each_online_cpu(i) {
- dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
- dev->state_count = 1;
- for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
- int num_substates;
- if (cstate > max_cstate) {
- printk(PREFIX "max_cstate %d reached\n",
- max_cstate);
- break;
- }
- /* does the state exist in CPUID.MWAIT? */
- num_substates = (mwait_substates >> ((cstate) * 4))
- & MWAIT_SUBSTATE_MASK;
- if (num_substates == 0)
- continue;
- /* is the state not enabled? */
- if (cpuidle_state_table[cstate].enter == NULL) {
- /* does the driver not know about the state? */
- if (*cpuidle_state_table[cstate].name == '\0')
- pr_debug(PREFIX "unaware of model 0x%x"
- " MWAIT %d please"
- " contact lenb@kernel.org",
- boot_cpu_data.x86_model, cstate);
- continue;
- }
- if ((cstate > 2) &&
- !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
- mark_tsc_unstable("TSC halts in idle"
- " states deeper than C2");
- dev->states[dev->state_count] = /* structure copy */
- cpuidle_state_table[cstate];
- dev->state_count += 1;
- }
- dev->cpu = i;
- if (cpuidle_register_device(dev)) {
- pr_debug(PREFIX "cpuidle_register_device %d failed!\n",
- i);
- intel_idle_cpuidle_devices_uninit();
- return -EIO;
- }
- }
- return 0;
- }
- static int __init intel_idle_init(void)
- {
- int retval;
- retval = intel_idle_probe();
- if (retval)
- return retval;
- retval = cpuidle_register_driver(&intel_idle_driver);
- if (retval) {
- printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
- cpuidle_get_driver()->name);
- return retval;
- }
- retval = intel_idle_cpuidle_devices_init();
- if (retval) {
- cpuidle_unregister_driver(&intel_idle_driver);
- return retval;
- }
- return 0;
- }
- static void __exit intel_idle_exit(void)
- {
- intel_idle_cpuidle_devices_uninit();
- cpuidle_unregister_driver(&intel_idle_driver);
- return;
- }
- module_init(intel_idle_init);
- module_exit(intel_idle_exit);
- module_param(max_cstate, int, 0444);
- MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
- MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
- MODULE_LICENSE("GPL");
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