2  * intel_idle.c - native hardware idle loop for modern Intel processors
18  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
34  *	for preventing entry into deep C-stats
41  * It it unaware of subsequent processors hot-added to the system.
45  * ACPI has a .suspend hack to turn off deep c-statees during suspend
51 /* un-comment DEBUG to enable pr_debug() statements */
65 #include <asm/intel-family.h>
76 static int max_cstate = CPUIDLE_STATE_MAX - 1;
88 	 * Hardware C-state auto-demotion may not always be optimal.
106  * and so we don't need cross-calls to keep it consistent.
113  * MWAIT takes an 8-bit "hint" in EAX "suggesting"
114  * the C-state (top nibble) and sub-state (bottom nibble)
856 		.exit_latency = 2000,
857 		.target_residency = 2000,
912 	unsigned long ecx = 1; /* break on interrupt flag */  in intel_idle()  local
913 	struct cpuidle_state *state = &drv->states[index];  in intel_idle()
914 	unsigned long eax = flg2MWAIT(state->flags);  in intel_idle()
923 	if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)  in intel_idle()
936 	mwait_idle_with_hints(eax, ecx);  in intel_idle()
945  * intel_idle_s2idle - simplified "enter" callback routine for suspend-to-idle
953 	unsigned long ecx = 1; /* break on interrupt flag */  in intel_idle_s2idle()  local
954 	unsigned long eax = flg2MWAIT(drv->states[index].flags);  in intel_idle_s2idle()
956 	mwait_idle_with_hints(eax, ecx);  in intel_idle_s2idle()
972 	msr_bits &= ~(icpu->auto_demotion_disable_flags);  in auto_demotion_disable()
1117 	unsigned int eax, ebx, ecx;  in intel_idle_probe()  local
1122 		return -EPERM;  in intel_idle_probe()
1131 		return -ENODEV;  in intel_idle_probe()
1136 		return -ENODEV;  in intel_idle_probe()
1140 		return -ENODEV;  in intel_idle_probe()
1142 	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);  in intel_idle_probe()
1144 	if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||  in intel_idle_probe()
1145 	    !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||  in intel_idle_probe()
1147 			return -ENODEV;  in intel_idle_probe()
1151 	icpu = (const struct idle_cpu *)id->driver_data;  in intel_idle_probe()
1152 	cpuidle_state_table = icpu->state_table;  in intel_idle_probe()
1178  * Tune IVT multi-socket targets
1183 	/* IVT uses a different table for 1-2, 3-4, and > 4 sockets */  in ivt_idle_state_table_update()
1272  * On SKL-H (model 0x5e) disable C8 and C9 if:
1278 	unsigned int eax, ebx, ecx, edx;  in sklh_idle_state_table_update()  local
1291 	/* PC10 is not enabled in PKG C-state limit */  in sklh_idle_state_table_update()
1295 	ecx = 0;  in sklh_idle_state_table_update()
1296 	cpuid(7, &eax, &ebx, &ecx, &edx);  in sklh_idle_state_table_update()
1308 	skl_cstates[5].disabled = 1;	/* C8-SKL */  in sklh_idle_state_table_update()
1309 	skl_cstates[6].disabled = 1;	/* C9-SKL */  in sklh_idle_state_table_update()
1314  * Update the default state_table for this CPU-id
1346 	drv->state_count = 1;  in intel_idle_cpuidle_driver_init()
1363 		/* number of sub-states for this state in CPUID.MWAIT */  in intel_idle_cpuidle_driver_init()
1367 		/* if NO sub-states for this state in CPUID, skip it */  in intel_idle_cpuidle_driver_init()
1384 		drv->states[drv->state_count] =	/* structure copy */  in intel_idle_cpuidle_driver_init()
1387 		drv->state_count += 1;  in intel_idle_cpuidle_driver_init()
1390 	if (icpu->byt_auto_demotion_disable_flag) {  in intel_idle_cpuidle_driver_init()
1407 	dev->cpu = cpu;  in intel_idle_cpu_init()
1411 		return -EIO;  in intel_idle_cpu_init()
1414 	if (icpu->auto_demotion_disable_flags)  in intel_idle_cpu_init()
1417 	if (icpu->disable_promotion_to_c1e)  in intel_idle_cpu_init()
1436 	if (!dev->registered)  in intel_idle_cpu_online()
1448 		return -ENODEV;  in intel_idle_init()
1456 		return -ENOMEM;  in intel_idle_init()
1463 		       drv ? drv->name : "none");  in intel_idle_init()
1492  * support "intel_idle.max_cstate=..." at boot and also a read-only export of
1493  * it at /sys/module/intel_idle/parameters/max_cstate -- so using module_param