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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2011 The ChromiumOS Authors. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2 of
* the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#include <console/console.h>
#include <cpu/intel/turbo.h>
#include <cpu/x86/msr.h>
#include <arch/cpu.h>
static int turbo_state = TURBO_UNKNOWN;
static const char *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 get_turbo_state(void)
{
struct cpuid_result cpuid_regs;
int turbo_en, turbo_cap;
msr_t msr;
/* 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 = rdmsr(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;
}
printk(BIOS_INFO, "Turbo is %s\n", turbo_state_desc[turbo_state]);
return turbo_state;
}
/*
* Try to enable Turbo mode.
*/
void enable_turbo(void)
{
msr_t msr;
/* Only possible if turbo is available but hidden */
if (get_turbo_state() == TURBO_DISABLED) {
/* Clear Turbo Disable bit in Misc Enables */
msr = rdmsr(MSR_IA32_MISC_ENABLES);
msr.hi &= ~H_MISC_DISABLE_TURBO;
wrmsr(MSR_IA32_MISC_ENABLES, msr);
/* Update cached turbo state */
turbo_state = TURBO_ENABLED;
printk(BIOS_INFO, "Turbo has been enabled\n");
}
}
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