/*
* 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;
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 = 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;
}
set_global_turbo_state(turbo_state);
printk(BIOS_INFO, "Turbo is %s\n", turbo_state_desc[turbo_state]);
return turbo_state;
}
/*
* Try to disable Turbo mode.
*/
void disable_turbo(void)
{
msr_t msr;
/* Set 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 */
set_global_turbo_state(TURBO_UNAVAILABLE);
printk(BIOS_INFO, "Turbo has been disabled\n");
}
/*
* 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 */
set_global_turbo_state(TURBO_ENABLED);
printk(BIOS_INFO, "Turbo has been enabled\n");
}
}
