arch/i386/kernel/acpi/cstate.c

   1 /*
   2  * arch/i386/kernel/acpi/cstate.c
   3  *
   4  * Copyright (C) 2005 Intel Corporation
   5  *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   6  *      - Added _PDC for SMP C-states on Intel CPUs
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/init.h>
  12 #include <linux/acpi.h>
  13 #include <linux/cpu.h>
  14 #include <linux/sched.h>
  15
  16 #include <acpi/processor.h>
  17 #include <asm/acpi.h>
  18
  19 /*
  20  * Initialize bm_flags based on the CPU cache properties
  21  * On SMP it depends on cache configuration
  22  * - When cache is not shared among all CPUs, we flush cache
  23  *   before entering C3.
  24  * - When cache is shared among all CPUs, we use bm_check
  25  *   mechanism as in UP case
  26  *
  27  * This routine is called only after all the CPUs are online
  28  */
  29 void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
  30                                         unsigned int cpu)
  31 {
  32         struct cpuinfo_x86 *c = cpu_data + cpu;
  33
  34         flags->bm_check = 0;
  35         if (num_online_cpus() == 1)
  36                 flags->bm_check = 1;
  37         else if (c->x86_vendor == X86_VENDOR_INTEL) {
  38                 /*
  39                  * Today all CPUs that support C3 share cache.
  40                  * TBD: This needs to look at cache shared map, once
  41                  * multi-core detection patch makes to the base.
  42                  */
  43                 flags->bm_check = 1;
  44         }
  45 }
  46 EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
  47
  48 /* The code below handles cstate entry with monitor-mwait pair on Intel*/
  49
  50 struct cstate_entry_s {
  51         struct {
  52                 unsigned int eax;
  53                 unsigned int ecx;
  54         } states[ACPI_PROCESSOR_MAX_POWER];
  55 };
  56 static struct cstate_entry_s *cpu_cstate_entry; /* per CPU ptr */
  57
  58 static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
  59
  60 #define MWAIT_SUBSTATE_MASK     (0xf)
  61 #define MWAIT_SUBSTATE_SIZE     (4)
  62
  63 #define CPUID_MWAIT_LEAF (5)
  64 #define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
  65 #define CPUID5_ECX_INTERRUPT_BREAK      (0x2)
  66
  67 #define MWAIT_ECX_INTERRUPT_BREAK       (0x1)
  68
  69 #define NATIVE_CSTATE_BEYOND_HALT       (2)
  70
  71 int acpi_processor_ffh_cstate_probe(unsigned int cpu,
  72                 struct acpi_processor_cx *cx, struct acpi_power_register *reg)
  73 {
  74         struct cstate_entry_s *percpu_entry;
  75         struct cpuinfo_x86 *c = cpu_data + cpu;
  76
  77         cpumask_t saved_mask;
  78         int retval;
  79         unsigned int eax, ebx, ecx, edx;
  80         unsigned int edx_part;
  81         unsigned int cstate_type; /* C-state type and not ACPI C-state type */
  82         unsigned int num_cstate_subtype;
  83
  84         if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF )
  85                 return -1;
  86
  87         if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
  88                 return -1;
  89
  90         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
  91         percpu_entry->states[cx->index].eax = 0;
  92         percpu_entry->states[cx->index].ecx = 0;
  93
  94         /* Make sure we are running on right CPU */
  95         saved_mask = current->cpus_allowed;
  96         retval = set_cpus_allowed(current, cpumask_of_cpu(cpu));
  97         if (retval)
  98                 return -1;
  99
 100         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
 101
 102         /* Check whether this particular cx_type (in CST) is supported or not */
 103         cstate_type = (cx->address >> MWAIT_SUBSTATE_SIZE) + 1;
 104         edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
 105         num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
 106
 107         retval = 0;
 108         if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
 109                 retval = -1;
 110                 goto out;
 111         }
 112
 113         /* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
 114         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
 115             !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
 116                 retval = -1;
 117                 goto out;
 118         }
 119         percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
 120
 121         /* Use the hint in CST */
 122         percpu_entry->states[cx->index].eax = cx->address;
 123
 124         if (!mwait_supported[cstate_type]) {
 125                 mwait_supported[cstate_type] = 1;
 126                 printk(KERN_DEBUG "Monitor-Mwait will be used to enter C-%d "
 127                        "state\n", cx->type);
 128         }
 129
 130 out:
 131         set_cpus_allowed(current, saved_mask);
 132         return retval;
 133 }
 134 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 135
 136 void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 137 {
 138         unsigned int cpu = smp_processor_id();
 139         struct cstate_entry_s *percpu_entry;
 140
 141         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 142         mwait_idle_with_hints(percpu_entry->states[cx->index].eax,
 143                               percpu_entry->states[cx->index].ecx);
 144 }
 145 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
 146
 147 static int __init ffh_cstate_init(void)
 148 {
 149         struct cpuinfo_x86 *c = &boot_cpu_data;
 150         if (c->x86_vendor != X86_VENDOR_INTEL)
 151                 return -1;
 152
 153         cpu_cstate_entry = alloc_percpu(struct cstate_entry_s);
 154         return 0;
 155 }
 156
 157 static void __exit ffh_cstate_exit(void)
 158 {
 159         free_percpu(cpu_cstate_entry);
 160         cpu_cstate_entry = NULL;
 161 }
 162
 163 arch_initcall(ffh_cstate_init);
 164 __exitcall(ffh_cstate_exit);