u-boot/arch/x86/cpu/turbo.c
Simon Glass 18739e2ccc x86: Add Intel speedstep and turbo mode code
Intel chips have a turbo mode where they can run faster for a short period
until they reach thermal limits. Add code to adjust and query this feature.

Signed-off-by: Simon Glass <sjg@chromium.org>
2014-11-25 06:34:02 -07:00

99 lines
2.2 KiB
C

/*
* From Coreboot file of the same name
*
* Copyright (C) 2011 The Chromium Authors.
*
* SPDX-License-Identifier: GPL-2.0
*/
#include <common.h>
#include <asm/cpu.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/turbo.h>
#if CONFIG_CPU_INTEL_TURBO_NOT_PACKAGE_SCOPED
static inline int get_global_turbo_state(void)
{
return TURBO_UNKNOWN;
}
static inline void set_global_turbo_state(int state)
{
}
#else
static int g_turbo_state = TURBO_UNKNOWN;
static inline int get_global_turbo_state(void)
{
return g_turbo_state;
}
static inline void set_global_turbo_state(int state)
{
g_turbo_state = state;
}
#endif
static const char *const turbo_state_desc[] = {
[TURBO_UNKNOWN] = "unknown",
[TURBO_UNAVAILABLE] = "unavailable",
[TURBO_DISABLED] = "available but hidden",
[TURBO_ENABLED] = "available and visible"
};
/*
* Determine the current state of Turbo and cache it for later.
* Turbo is a package level config so it does not need to be
* enabled on every core.
*/
int turbo_get_state(void)
{
struct cpuid_result cpuid_regs;
int turbo_en, turbo_cap;
msr_t msr;
int turbo_state = get_global_turbo_state();
/* Return cached state if available */
if (turbo_state != TURBO_UNKNOWN)
return turbo_state;
cpuid_regs = cpuid(CPUID_LEAF_PM);
turbo_cap = !!(cpuid_regs.eax & PM_CAP_TURBO_MODE);
msr = msr_read(MSR_IA32_MISC_ENABLES);
turbo_en = !(msr.hi & H_MISC_DISABLE_TURBO);
if (!turbo_cap && turbo_en) {
/* Unavailable */
turbo_state = TURBO_UNAVAILABLE;
} else if (!turbo_cap && !turbo_en) {
/* Available but disabled */
turbo_state = TURBO_DISABLED;
} else if (turbo_cap && turbo_en) {
/* Available */
turbo_state = TURBO_ENABLED;
}
set_global_turbo_state(turbo_state);
debug("Turbo is %s\n", turbo_state_desc[turbo_state]);
return turbo_state;
}
void turbo_enable(void)
{
msr_t msr;
/* Only possible if turbo is available but hidden */
if (turbo_get_state() == TURBO_DISABLED) {
/* Clear Turbo Disable bit in Misc Enables */
msr = msr_read(MSR_IA32_MISC_ENABLES);
msr.hi &= ~H_MISC_DISABLE_TURBO;
msr_write(MSR_IA32_MISC_ENABLES, msr);
/* Update cached turbo state */
set_global_turbo_state(TURBO_ENABLED);
debug("Turbo has been enabled\n");
}
}