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linux/drivers/cpufreq/speedstep-lib.c
Mikulas Patocka d4d4eda237 cpufreq: speedstep-smi: enable interrupts when waiting 
On Dell Latitude C600 laptop with Pentium 3 850MHz processor, the
speedstep-smi driver sometimes loads and sometimes doesn't load with
"change to state X failed" message.

The hardware sometimes refuses to change frequency and in this case, we
need to retry later. I found out that we need to enable interrupts while
waiting. When we enable interrupts, the hardware blockage that prevents
frequency transition resolves and the transition is possible. With
disabled interrupts, the blockage doesn't resolve (no matter how long do
we wait). The exact reasons for this hardware behavior are unknown.

This patch enables interrupts in the function speedstep_set_state that can
be called with disabled interrupts. However, this function is called with
disabled interrupts only from speedstep_get_freqs, so it shouldn't cause
any problem.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com
Cc: All applicable <stable@vger.kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2015-02-12 02:02:52 +01:00

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/*
* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
*
* Licensed under the terms of the GNU GPL License version 2.
*
* Library for common functions for Intel SpeedStep v.1 and v.2 support
*
* BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
*/
#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 */
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 */
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:
printk(KERN_ERR "PCORE - MSR_FSB_FREQ undefined value");
}
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 */
unsigned int 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_mask is %x\n", ebx, c->x86_mask);
switch (c->x86_mask) {
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_mask == 0x01) {
pr_debug("early PIII version\n");
return SPEEDSTEP_CPU_PIII_C_EARLY;
} else
return SPEEDSTEP_CPU_PIII_C;
}
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;
struct timeval 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)
do_gettimeofday(&tv1);
/* switch to high state */
set_state(SPEEDSTEP_HIGH);
/* end latency measurement */
if (transition_latency)
do_gettimeofday(&tv2);
*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 = (tv2.tv_sec - tv1.tv_sec) * USEC_PER_SEC +
tv2.tv_usec - tv1.tv_usec;
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) {
printk(KERN_WARNING PFX "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");
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