arch/x86/cpu/turbo.c

   1 /*
   2  * From Coreboot file of the same name
   3  *
   4  * Copyright (C) 2011 The Chromium Authors.
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0
   7  */
   8
   9 #include <common.h>
  10 #include <asm/cpu.h>
  11 #include <asm/msr.h>
  12 #include <asm/processor.h>
  13 #include <asm/turbo.h>
  14
  15 #if CONFIG_CPU_INTEL_TURBO_NOT_PACKAGE_SCOPED
  16 static inline int get_global_turbo_state(void)
  17 {
  18         return TURBO_UNKNOWN;
  19 }
  20
  21 static inline void set_global_turbo_state(int state)
  22 {
  23 }
  24 #else
  25 static int g_turbo_state = TURBO_UNKNOWN;
  26
  27 static inline int get_global_turbo_state(void)
  28 {
  29         return g_turbo_state;
  30 }
  31
  32 static inline void set_global_turbo_state(int state)
  33 {
  34         g_turbo_state = state;
  35 }
  36 #endif
  37
  38 static const char *const turbo_state_desc[] = {
  39         [TURBO_UNKNOWN]         = "unknown",
  40         [TURBO_UNAVAILABLE]     = "unavailable",
  41         [TURBO_DISABLED]        = "available but hidden",
  42         [TURBO_ENABLED]         = "available and visible"
  43 };
  44
  45 /*
  46  * Determine the current state of Turbo and cache it for later.
  47  * Turbo is a package level config so it does not need to be
  48  * enabled on every core.
  49  */
  50 int turbo_get_state(void)
  51 {
  52         struct cpuid_result cpuid_regs;
  53         int turbo_en, turbo_cap;
  54         msr_t msr;
  55         int turbo_state = get_global_turbo_state();
  56
  57         /* Return cached state if available */
  58         if (turbo_state != TURBO_UNKNOWN)
  59                 return turbo_state;
  60
  61         cpuid_regs = cpuid(CPUID_LEAF_PM);
  62         turbo_cap = !!(cpuid_regs.eax & PM_CAP_TURBO_MODE);
  63
  64         msr = msr_read(MSR_IA32_MISC_ENABLES);
  65         turbo_en = !(msr.hi & H_MISC_DISABLE_TURBO);
  66
  67         if (!turbo_cap && turbo_en) {
  68                 /* Unavailable */
  69                 turbo_state = TURBO_UNAVAILABLE;
  70         } else if (!turbo_cap && !turbo_en) {
  71                 /* Available but disabled */
  72                 turbo_state = TURBO_DISABLED;
  73         } else if (turbo_cap && turbo_en) {
  74                 /* Available */
  75                 turbo_state = TURBO_ENABLED;
  76         }
  77
  78         set_global_turbo_state(turbo_state);
  79         debug("Turbo is %s\n", turbo_state_desc[turbo_state]);
  80         return turbo_state;
  81 }
  82
  83 void turbo_enable(void)
  84 {
  85         msr_t msr;
  86
  87         /* Only possible if turbo is available but hidden */
  88         if (turbo_get_state() == TURBO_DISABLED) {
  89                 /* Clear Turbo Disable bit in Misc Enables */
  90                 msr = msr_read(MSR_IA32_MISC_ENABLES);
  91                 msr.hi &= ~H_MISC_DISABLE_TURBO;
  92                 msr_write(MSR_IA32_MISC_ENABLES, msr);
  93
  94                 /* Update cached turbo state */
  95                 set_global_turbo_state(TURBO_ENABLED);
  96                 debug("Turbo has been enabled\n");
  97         }
  98 }