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/export.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 #include <asm/mwait.h>
  17 #include <asm/special_insns.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 MP CPUs that support C3 share cache.
  40                  * And caches should not be flushed by software while
  41                  * entering C3 type state.
  42                  */
  43                 flags->bm_check = 1;
  44         }
  45
  46         /*
  47          * On all recent Intel platforms, ARB_DISABLE is a nop.
  48          * So, set bm_control to zero to indicate that ARB_DISABLE
  49          * is not required while entering C3 type state on
  50          * P4, Core and beyond CPUs
  51          */
  52         if (c->x86_vendor == X86_VENDOR_INTEL &&
  53             (c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 0x0f)))
  54                         flags->bm_control = 0;
  55 }
  56 EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
  57
  58 /* The code below handles cstate entry with monitor-mwait pair on Intel*/
  59
  60 struct cstate_entry {
  61         struct {
  62                 unsigned int eax;
  63                 unsigned int ecx;
  64         } states[ACPI_PROCESSOR_MAX_POWER];
  65 };
  66 static struct cstate_entry __percpu *cpu_cstate_entry;  /* per CPU ptr */
  67
  68 static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
  69
  70 #define NATIVE_CSTATE_BEYOND_HALT       (2)
  71
  72 static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
  73 {
  74         struct acpi_processor_cx *cx = _cx;
  75         long retval;
  76         unsigned int eax, ebx, ecx, edx;
  77         unsigned int edx_part;
  78         unsigned int cstate_type; /* C-state type and not ACPI C-state type */
  79         unsigned int num_cstate_subtype;
  80
  81         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
  82
  83         /* Check whether this particular cx_type (in CST) is supported or not */
  84         cstate_type = ((cx->address >> MWAIT_SUBSTATE_SIZE) &
  85                         MWAIT_CSTATE_MASK) + 1;
  86         edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
  87         num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
  88
  89         retval = 0;
  90         /* If the HW does not support any sub-states in this C-state */
  91         if (num_cstate_subtype == 0) {
  92                 pr_warn(FW_BUG "ACPI MWAIT C-state 0x%x not supported by HW (0x%x)\n", cx->address, edx_part);
  93                 retval = -1;
  94                 goto out;
  95         }
  96
  97         /* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
  98         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
  99             !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
 100                 retval = -1;
 101                 goto out;
 102         }
 103
 104         if (!mwait_supported[cstate_type]) {
 105                 mwait_supported[cstate_type] = 1;
 106                 printk(KERN_DEBUG
 107                         "Monitor-Mwait will be used to enter C-%d "
 108                         "state\n", cx->type);
 109         }
 110         snprintf(cx->desc,
 111                         ACPI_CX_DESC_LEN, "ACPI FFH INTEL MWAIT 0x%x",
 112                         cx->address);
 113 out:
 114         return retval;
 115 }
 116
 117 int acpi_processor_ffh_cstate_probe(unsigned int cpu,
 118                 struct acpi_processor_cx *cx, struct acpi_power_register *reg)
 119 {
 120         struct cstate_entry *percpu_entry;
 121         struct cpuinfo_x86 *c = &cpu_data(cpu);
 122         long retval;
 123
 124         if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
 125                 return -1;
 126
 127         if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
 128                 return -1;
 129
 130         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 131         percpu_entry->states[cx->index].eax = 0;
 132         percpu_entry->states[cx->index].ecx = 0;
 133
 134         /* Make sure we are running on right CPU */
 135
 136         retval = work_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx);
 137         if (retval == 0) {
 138                 /* Use the hint in CST */
 139                 percpu_entry->states[cx->index].eax = cx->address;
 140                 percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
 141         }
 142
 143         /*
 144          * For _CST FFH on Intel, if GAS.access_size bit 1 is cleared,
 145          * then we should skip checking BM_STS for this C-state.
 146          * ref: "Intel Processor Vendor-Specific ACPI Interface Specification"
 147          */
 148         if ((c->x86_vendor == X86_VENDOR_INTEL) && !(reg->access_size & 0x2))
 149                 cx->bm_sts_skip = 1;
 150
 151         return retval;
 152 }
 153 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 154
 155 void acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 156 {
 157         unsigned int cpu = smp_processor_id();
 158         struct cstate_entry *percpu_entry;
 159
 160         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 161         mwait_idle_with_hints(percpu_entry->states[cx->index].eax,
 162                               percpu_entry->states[cx->index].ecx);
 163 }
 164 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
 165
 166 static int __init ffh_cstate_init(void)
 167 {
 168         struct cpuinfo_x86 *c = &boot_cpu_data;
 169         if (c->x86_vendor != X86_VENDOR_INTEL)
 170                 return -1;
 171
 172         cpu_cstate_entry = alloc_percpu(struct cstate_entry);
 173         return 0;
 174 }
 175
 176 static void __exit ffh_cstate_exit(void)
 177 {
 178         free_percpu(cpu_cstate_entry);
 179         cpu_cstate_entry = NULL;
 180 }
 181
 182 arch_initcall(ffh_cstate_init);
 183 __exitcall(ffh_cstate_exit);