// SPDX-License-Identifier: GPL-2.0-only
/*
* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
*
* Library for common functions for Intel SpeedStep v.1 and v.2 support
*
* BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <asm/msr.h>
#include <asm/tsc.h>
#include "speedstep-lib.h"
#define PFX "speedstep-lib: "
#ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK
static int relaxed_check;
#else
#define relaxed_check 0
#endif
/*********************************************************************
* GET PROCESSOR CORE SPEED IN KHZ *
*********************************************************************/
static unsigned int pentium3_get_frequency(enum speedstep_processor processor)
{
/* See table 14 of p3_ds.pdf and table 22 of 29834003.pdf */
static const struct {
unsigned int ratio; /* Frequency Multiplier (x10) */
u8 bitmap; /* power on configuration bits
[27, 25:22] (in MSR 0x2a) */
} msr_decode_mult[] = {
{ 30, 0x01 },
{ 35, 0x05 },
{ 40, 0x02 },
{ 45, 0x06 },
{ 50, 0x00 },
{ 55, 0x04 },
{ 60, 0x0b },
{ 65, 0x0f },
{ 70, 0x09 },
{ 75, 0x0d },
{ 80, 0x0a },
{ 85, 0x26 },
{ 90, 0x20 },
{ 100, 0x2b },
{ 0, 0xff } /* error or unknown value */
};
/* PIII(-M) FSB settings: see table b1-b of 24547206.pdf */
static const struct {
unsigned int value; /* Front Side Bus speed in MHz */
u8 bitmap; /* power on configuration bits [18: 19]
(in MSR 0x2a) */
} msr_decode_fsb[] = {
{ 66, 0x0 },
{ 100, 0x2 },
{ 133, 0x1 },
{ 0, 0xff}
};
u32 msr_lo, msr_tmp;
int i = 0, j = 0;
/* read MSR 0x2a - we only need the low 32 bits */
rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
pr_debug("P3 - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
msr_tmp = msr_lo;
/* decode the FSB */
msr_tmp &= 0x00c0000;
msr_tmp >>= 18;
while (msr_tmp != msr_decode_fsb[i].bitmap) {
if (msr_decode_fsb[i].bitmap == 0xff)
return 0;
i++;
}
/* decode the multiplier */
if (processor == SPEEDSTEP_CPU_PIII_C_EARLY) {
pr_debug("workaround for early PIIIs\n");
msr_lo &= 0x03c00000;
} else
msr_lo &= 0x0bc00000;
msr_lo >>= 22;
while (msr_lo != msr_decode_mult[j].bitmap) {
if (msr_decode_mult[j].bitmap == 0xff)
return 0;
j++;
}
pr_debug("speed is %u\n",
(msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100));
return msr_decode_mult[j].ratio * msr_decode_fsb[i].value * 100;
}
static unsigned int pentiumM_get_frequency(void)
{
u32 msr_lo, msr_tmp;
rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
pr_debug("PM - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n", msr_lo, msr_tmp);
/* see table B-2 of 24547212.pdf */
if (msr_lo & 0x00040000) {
printk(KERN_DEBUG PFX "PM - invalid FSB: 0x%x 0x%x\n",
msr_lo, msr_tmp);
return 0;
}
msr_tmp = (msr_lo >> 22) & 0x1f;
pr_debug("bits 22-26 are 0x%x, speed is %u\n",
msr_tmp, (msr_tmp * 100 * 1000));
return msr_tmp * 100 * 1000;
}
static unsigned int pentium_core_get_frequency(void)
{
u32 fsb = 0;
u32 msr_lo, msr_tmp;
int ret;
rdmsr(MSR_FSB_FREQ, msr_lo, msr_tmp);
/* see table B-2 of 25366920.pdf */
switch (msr_lo & 0x07) {
case 5:
fsb = 100000;
break;
case 1:
fsb = 133333;
break;
case 3:
fsb = 166667;
break;
case 2:
fsb = 200000;
break;
case 0:
fsb = 266667;
break;
case 4:
fsb = 333333;
break;
default:
pr_err("PCORE - MSR_FSB_FREQ undefined value\n");
}
rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_tmp);
pr_debug("PCORE - MSR_IA32_EBL_CR_POWERON: 0x%x 0x%x\n",
msr_lo, msr_tmp);
msr_tmp = (msr_lo >> 22) & 0x1f;
pr_debug("bits 22-26 are 0x%x, speed is %u\n",
msr_tmp, (msr_tmp * fsb));
ret = (msr_tmp * fsb);
return ret;
}
static unsigned int pentium4_get_frequency(void)
{
struct cpuinfo_x86 *c = &boot_cpu_data;
u32 msr_lo, msr_hi, mult;
unsigned int fsb = 0;
unsigned int ret;
u8 fsb_code;
/* Pentium 4 Model 0 and 1 do not have the Core Clock Frequency
* to System Bus Frequency Ratio Field in the Processor Frequency
* Configuration Register of the MSR. Therefore the current
* frequency cannot be calculated and has to be measured.
*/
if (c->x86_model < 2)
return cpu_khz;
rdmsr(0x2c, msr_lo, msr_hi);
pr_debug("P4 - MSR_EBC_FREQUENCY_ID: 0x%x 0x%x\n", msr_lo, msr_hi);
/* decode the FSB: see IA-32 Intel (C) Architecture Software
* Developer's Manual, Volume 3: System Prgramming Guide,
* revision #12 in Table B-1: MSRs in the Pentium 4 and
* Intel Xeon Processors, on page B-4 and B-5.
*/
fsb_code = (msr_lo >> 16) & 0x7;
switch (fsb_code) {
case 0:
fsb = 100 * 1000;
break;
case 1:
fsb = 13333 * 10;
break;
case 2:
fsb = 200 * 1000;
break;
}
if (!fsb)
printk(KERN_DEBUG PFX "couldn't detect FSB speed. "
"Please send an e-mail to <linux@brodo.de>\n");
/* Multiplier. */
mult = msr_lo >> 24;
pr_debug("P4 - FSB %u kHz; Multiplier %u; Speed %u kHz\n",
fsb, mult, (fsb * mult));
ret = (fsb * mult);
return ret;
}
/* Warning: may get called from smp_call_function_single. */
unsigned int speedstep_get_frequency(enum speedstep_processor processor)
{
switch (processor) {
case SPEEDSTEP_CPU_PCORE:
return pentium_core_get_frequency();
case SPEEDSTEP_CPU_PM:
return pentiumM_get_frequency();
case SPEEDSTEP_CPU_P4D:
case SPEEDSTEP_CPU_P4M:
return pentium4_get_frequency();
case SPEEDSTEP_CPU_PIII_T:
case SPEEDSTEP_CPU_PIII_C:
case SPEEDSTEP_CPU_PIII_C_EARLY:
return pentium3_get_frequency(processor);
default:
return 0;
};
return 0;
}
EXPORT_SYMBOL_GPL(speedstep_get_frequency);
/*********************************************************************
* DETECT SPEEDSTEP-CAPABLE PROCESSOR *
*********************************************************************/
/* Keep in sync with the x86_cpu_id tables in the different modules */
enum speedstep_processor speedstep_detect_processor(void)
{
struct cpuinfo_x86 *c = &cpu_data(0);
u32 ebx, msr_lo, msr_hi;
pr_debug("x86: %x, model: %x\n", c->x86, c->x86_model);
if ((c->x86_vendor != X86_VENDOR_INTEL) ||
((c->x86 != 6) && (c->x86 != 0xF)))
return 0;
if (c->x86 == 0xF) {
/* Intel Mobile Pentium 4-M
* or Intel Mobile Pentium 4 with 533 MHz FSB */
if (c->x86_model != 2)
return 0;
ebx = cpuid_ebx(0x00000001);
ebx &= 0x000000FF;
pr_debug("ebx value is %x, x86_stepping is %x\n", ebx, c->x86_stepping);
switch (c->x86_stepping) {
case 4:
/*
* B-stepping [M-P4-M]
* sample has ebx = 0x0f, production has 0x0e.
*/
if ((ebx == 0x0e) || (ebx == 0x0f))
return SPEEDSTEP_CPU_P4M;
break;
case 7:
/*
* C-stepping [M-P4-M]
* needs to have ebx=0x0e, else it's a celeron:
* cf. 25130917.pdf / page 7, footnote 5 even
* though 25072120.pdf / page 7 doesn't say
* samples are only of B-stepping...
*/
if (ebx == 0x0e)
return SPEEDSTEP_CPU_P4M;
break;
case 9:
/*
* D-stepping [M-P4-M or M-P4/533]
*
* this is totally strange: CPUID 0x0F29 is
* used by M-P4-M, M-P4/533 and(!) Celeron CPUs.
* The latter need to be sorted out as they don't
* support speedstep.
* Celerons with CPUID 0x0F29 may have either
* ebx=0x8 or 0xf -- 25130917.pdf doesn't say anything
* specific.
* M-P4-Ms may have either ebx=0xe or 0xf [see above]
* M-P4/533 have either ebx=0xe or 0xf. [25317607.pdf]
* also, M-P4M HTs have ebx=0x8, too
* For now, they are distinguished by the model_id
* string
*/
if ((ebx == 0x0e) ||
(strstr(c->x86_model_id,
"Mobile Intel(R) Pentium(R) 4") != NULL))
return SPEEDSTEP_CPU_P4M;
break;
default:
break;
}
return 0;
}
switch (c->x86_model) {
case 0x0B: /* Intel PIII [Tualatin] */
/* cpuid_ebx(1) is 0x04 for desktop PIII,
* 0x06 for mobile PIII-M */
ebx = cpuid_ebx(0x00000001);
pr_debug("ebx is %x\n", ebx);
ebx &= 0x000000FF;
if (ebx != 0x06)
return 0;
/* So far all PIII-M processors support SpeedStep. See
* Intel's 24540640.pdf of June 2003
*/
return SPEEDSTEP_CPU_PIII_T;
case 0x08: /* Intel PIII [Coppermine] */
/* all mobile PIII Coppermines have FSB 100 MHz
* ==> sort out a few desktop PIIIs. */
rdmsr(MSR_IA32_EBL_CR_POWERON, msr_lo, msr_hi);
pr_debug("Coppermine: MSR_IA32_EBL_CR_POWERON is 0x%x, 0x%x\n",
msr_lo, msr_hi);
msr_lo &= 0x00c0000;
if (msr_lo != 0x0080000)
return 0;
/*
* If the processor is a mobile version,
* platform ID has bit 50 set
* it has SpeedStep technology if either
* bit 56 or 57 is set
*/
rdmsr(MSR_IA32_PLATFORM_ID, msr_lo, msr_hi);
pr_debug("Coppermine: MSR_IA32_PLATFORM ID is 0x%x, 0x%x\n",
msr_lo, msr_hi);
if ((msr_hi & (1<<18)) &&
(relaxed_check ? 1 : (msr_hi & (3<<24)))) {
if (c->x86_stepping == 0x01) {
pr_debug("early PIII version\n");
return SPEEDSTEP_CPU_PIII_C_EARLY;
} else
return SPEEDSTEP_CPU_PIII_C;
}
/* fall through */
default:
return 0;
}
}
EXPORT_SYMBOL_GPL(speedstep_detect_processor);
/*********************************************************************
* DETECT SPEEDSTEP SPEEDS *
*********************************************************************/
unsigned int speedstep_get_freqs(enum speedstep_processor processor,
unsigned int *low_speed,
unsigned int *high_speed,
unsigned int *transition_latency,
void (*set_state) (unsigned int state))
{
unsigned int prev_speed;
unsigned int ret = 0;
unsigned long flags;
ktime_t tv1, tv2;
if ((!processor) || (!low_speed) || (!high_speed) || (!set_state))
return -EINVAL;
pr_debug("trying to determine both speeds\n");
/* get current speed */
prev_speed = speedstep_get_frequency(processor);
if (!prev_speed)
return -EIO;
pr_debug("previous speed is %u\n", prev_speed);
preempt_disable();
local_irq_save(flags);
/* switch to low state */
set_state(SPEEDSTEP_LOW);
*low_speed = speedstep_get_frequency(processor);
if (!*low_speed) {
ret = -EIO;
goto out;
}
pr_debug("low speed is %u\n", *low_speed);
/* start latency measurement */
if (transition_latency)
tv1 = ktime_get();
/* switch to high state */
set_state(SPEEDSTEP_HIGH);
/* end latency measurement */
if (transition_latency)
tv2 = ktime_get();
*high_speed = speedstep_get_frequency(processor);
if (!*high_speed) {
ret = -EIO;
goto out;
}
pr_debug("high speed is %u\n", *high_speed);
if (*low_speed == *high_speed) {
ret = -ENODEV;
goto out;
}
/* switch to previous state, if necessary */
if (*high_speed != prev_speed)
set_state(SPEEDSTEP_LOW);
if (transition_latency) {
*transition_latency = ktime_to_us(ktime_sub(tv2, tv1));
pr_debug("transition latency is %u uSec\n", *transition_latency);
/* convert uSec to nSec and add 20% for safety reasons */
*transition_latency *= 1200;
/* check if the latency measurement is too high or too low
* and set it to a safe value (500uSec) in that case
*/
if (*transition_latency > 10000000 ||
*transition_latency < 50000) {
pr_warn("frequency transition measured seems out of range (%u nSec), falling back to a safe one of %u nSec\n",
*transition_latency, 500000);
*transition_latency = 500000;
}
}
out:
local_irq_restore(flags);
preempt_enable();
return ret;
}
EXPORT_SYMBOL_GPL(speedstep_get_freqs);
#ifdef CONFIG_X86_SPEEDSTEP_RELAXED_CAP_CHECK
module_param(relaxed_check, int, 0444);
MODULE_PARM_DESC(relaxed_check,
"Don't do all checks for speedstep capability.");
#endif
MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
MODULE_DESCRIPTION("Library for Intel SpeedStep 1 or 2 cpufreq drivers.");
MODULE_LICENSE("GPL");
