arch/x86/kernel/acpi/cstate.c

   1 /*
   2  * Copyright (C) 2005 Intel Corporation
   3  *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   4  *      - Added _PDC for SMP C-states on Intel CPUs
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/acpi.h>
  11 #include <linux/cpu.h>
  12 #include <linux/sched.h>
  13
  14 #include <acpi/processor.h>
  15 #include <asm/acpi.h>
  16
  17 /*
  18  * Initialize bm_flags based on the CPU cache properties
  19  * On SMP it depends on cache configuration
  20  * - When cache is not shared among all CPUs, we flush cache
  21  *   before entering C3.
  22  * - When cache is shared among all CPUs, we use bm_check
  23  *   mechanism as in UP case
  24  *
  25  * This routine is called only after all the CPUs are online
  26  */
  27 void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
  28                                         unsigned int cpu)
  29 {
  30         struct cpuinfo_x86 *c = &cpu_data(cpu);
  31
  32         flags->bm_check = 0;
  33         if (num_online_cpus() == 1)
  34                 flags->bm_check = 1;
  35         else if (c->x86_vendor == X86_VENDOR_INTEL) {
  36                 /*
  37                  * Today all CPUs that support C3 share cache.
  38                  * TBD: This needs to look at cache shared map, once
  39                  * multi-core detection patch makes to the base.
  40                  */
  41                 flags->bm_check = 1;
  42         }
  43 }
  44 EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
  45
  46 /* The code below handles cstate entry with monitor-mwait pair on Intel*/
  47
  48 struct cstate_entry {
  49         struct {
  50                 unsigned int eax;
  51                 unsigned int ecx;
  52         } states[ACPI_PROCESSOR_MAX_POWER];
  53 };
  54 static struct cstate_entry *cpu_cstate_entry;   /* per CPU ptr */
  55
  56 static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
  57
  58 #define MWAIT_SUBSTATE_MASK     (0xf)
  59 #define MWAIT_SUBSTATE_SIZE     (4)
  60
  61 #define CPUID_MWAIT_LEAF (5)
  62 #define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
  63 #define CPUID5_ECX_INTERRUPT_BREAK      (0x2)
  64
  65 #define MWAIT_ECX_INTERRUPT_BREAK       (0x1)
  66
  67 #define NATIVE_CSTATE_BEYOND_HALT       (2)
  68
  69 static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
  70 {
  71         struct acpi_processor_cx *cx = _cx;
  72         long retval;
  73         unsigned int eax, ebx, ecx, edx;
  74         unsigned int edx_part;
  75         unsigned int cstate_type; /* C-state type and not ACPI C-state type */
  76         unsigned int num_cstate_subtype;
  77
  78         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
  79
  80         /* Check whether this particular cx_type (in CST) is supported or not */
  81         cstate_type = (cx->address >> MWAIT_SUBSTATE_SIZE) + 1;
  82         edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
  83         num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
  84
  85         retval = 0;
  86         if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
  87                 retval = -1;
  88                 goto out;
  89         }
  90
  91         /* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
  92         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
  93             !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
  94                 retval = -1;
  95                 goto out;
  96         }
  97
  98         if (!mwait_supported[cstate_type]) {
  99                 mwait_supported[cstate_type] = 1;
 100                 printk(KERN_DEBUG
 101                         "Monitor-Mwait will be used to enter C-%d "
 102                         "state\n", cx->type);
 103         }
 104         snprintf(cx->desc,
 105                         ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
 106                         cx->address);
 107 out:
 108         return retval;
 109 }
 110
 111 int acpi_processor_ffh_cstate_probe(unsigned int cpu,
 112                 struct acpi_processor_cx *cx, struct acpi_power_register *reg)
 113 {
 114         struct cstate_entry *percpu_entry;
 115         struct cpuinfo_x86 *c = &cpu_data(cpu);
 116         long retval;
 117
 118         if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
 119                 return -1;
 120
 121         if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
 122                 return -1;
 123
 124         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 125         percpu_entry->states[cx->index].eax = 0;
 126         percpu_entry->states[cx->index].ecx = 0;
 127
 128         /* Make sure we are running on right CPU */
 129
 130         retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
 131         if (retval == 0) {
 132                 /* Use the hint in CST */
 133                 percpu_entry->states[cx->index].eax = cx->address;
 134                 percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
 135         }
 136         return retval;
 137 }
 138 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 139
 140 void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 141 {
 142         unsigned int cpu = smp_processor_id();
 143         struct cstate_entry *percpu_entry;
 144
 145         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 146         mwait_idle_with_hints(percpu_entry->states[cx->index].eax,
 147                               percpu_entry->states[cx->index].ecx);
 148 }
 149 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
 150
 151 static int __init ffh_cstate_init(void)
 152 {
 153         struct cpuinfo_x86 *c = &boot_cpu_data;
 154         if (c->x86_vendor != X86_VENDOR_INTEL)
 155                 return -1;
 156
 157         cpu_cstate_entry = alloc_percpu(struct cstate_entry);
 158         return 0;
 159 }
 160
 161 static void __exit ffh_cstate_exit(void)
 162 {
 163         free_percpu(cpu_cstate_entry);
 164         cpu_cstate_entry = NULL;
 165 }
 166
 167 arch_initcall(ffh_cstate_init);
 168 __exitcall(ffh_cstate_exit);