/*
* cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
* M (part of the Centrino chipset).
*
* Since the original Pentium M, most new Intel CPUs support Enhanced
* SpeedStep.
*
* Despite the "SpeedStep" in the name, this is almost entirely unlike
* traditional SpeedStep.
*
* Modelled on speedstep.c
*
* Copyright (C) 2003 Jeremy Fitzhardinge <jeremy@goop.org>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/sched.h> /* current */
#include <linux/delay.h>
#include <linux/compiler.h>
#include <linux/gfp.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
#define PFX "speedstep-centrino: "
#define MAINTAINER "cpufreq@vger.kernel.org"
#define INTEL_MSR_RANGE (0xffff)
struct cpu_id
{
__u8 x86; /* CPU family */
__u8 x86_model; /* model */
__u8 x86_mask; /* stepping */
};
enum {
CPU_BANIAS,
CPU_DOTHAN_A1,
CPU_DOTHAN_A2,
CPU_DOTHAN_B0,
CPU_MP4HT_D0,
CPU_MP4HT_E0,
};
static const struct cpu_id cpu_ids[] = {
[CPU_BANIAS] = { 6, 9, 5 },
[CPU_DOTHAN_A1] = { 6, 13, 1 },
[CPU_DOTHAN_A2] = { 6, 13, 2 },
[CPU_DOTHAN_B0] = { 6, 13, 6 },
[CPU_MP4HT_D0] = {15, 3, 4 },
[CPU_MP4HT_E0] = {15, 4, 1 },
};
#define N_IDS ARRAY_SIZE(cpu_ids)
struct cpu_model
{
const struct cpu_id *cpu_id;
const char *model_name;
unsigned max_freq; /* max clock in kHz */
struct cpufreq_frequency_table *op_points; /* clock/voltage pairs */
};
static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
const struct cpu_id *x);
/* Operating points for current CPU */
static DEFINE_PER_CPU(struct cpu_model *, centrino_model);
static DEFINE_PER_CPU(const struct cpu_id *, centrino_cpu);
static struct cpufreq_driver centrino_driver;
#ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE
/* Computes the correct form for IA32_PERF_CTL MSR for a particular
frequency/voltage operating point; frequency in MHz, volts in mV.
This is stored as "index" in the structure. */
#define OP(mhz, mv) \
{ \
.frequency = (mhz) * 1000, \
.index = (((mhz)/100) << 8) | ((mv - 700) / 16) \
}
/*
* These voltage tables were derived from the Intel Pentium M
* datasheet, document 25261202.pdf, Table 5. I have verified they
* are consistent with my IBM ThinkPad X31, which has a 1.3GHz Pentium
* M.
*/
/* Ultra Low Voltage Intel Pentium M processor 900MHz (Banias) */
static struct cpufreq_frequency_table banias_900[] =
{
OP(600, 844),
OP(800, 988),
OP(900, 1004),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Ultra Low Voltage Intel Pentium M processor 1000MHz (Banias) */
static struct cpufreq_frequency_table banias_1000[] =
{
OP(600, 844),
OP(800, 972),
OP(900, 988),
OP(1000, 1004),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Low Voltage Intel Pentium M processor 1.10GHz (Banias) */
static struct cpufreq_frequency_table banias_1100[] =
{
OP( 600, 956),
OP( 800, 1020),
OP( 900, 1100),
OP(1000, 1164),
OP(1100, 1180),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Low Voltage Intel Pentium M processor 1.20GHz (Banias) */
static struct cpufreq_frequency_table banias_1200[] =
{
OP( 600, 956),
OP( 800, 1004),
OP( 900, 1020),
OP(1000, 1100),
OP(1100, 1164),
OP(1200, 1180),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Intel Pentium M processor 1.30GHz (Banias) */
static struct cpufreq_frequency_table banias_1300[] =
{
OP( 600, 956),
OP( 800, 1260),
OP(1000, 1292),
OP(1200, 1356),
OP(1300, 1388),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Intel Pentium M processor 1.40GHz (Banias) */
static struct cpufreq_frequency_table banias_1400[] =
{
OP( 600, 956),
OP( 800, 1180),
OP(1000, 1308),
OP(1200, 1436),
OP(1400, 1484),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Intel Pentium M processor 1.50GHz (Banias) */
static struct cpufreq_frequency_table banias_1500[] =
{
OP( 600, 956),
OP( 800, 1116),
OP(1000, 1228),
OP(1200, 1356),
OP(1400, 1452),
OP(1500, 1484),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Intel Pentium M processor 1.60GHz (Banias) */
static struct cpufreq_frequency_table banias_1600[] =
{
OP( 600, 956),
OP( 800, 1036),
OP(1000, 1164),
OP(1200, 1276),
OP(1400, 1420),
OP(1600, 1484),
{ .frequency = CPUFREQ_TABLE_END }
};
/* Intel Pentium M processor 1.70GHz (Banias) */
static struct cpufreq_frequency_table banias_1700[] =
{
OP( 600, 956),
OP( 800, 1004),
OP(1000, 1116),
OP(1200, 1228),
OP(1400, 1308),
OP(1700, 1484),
{ .frequency = CPUFREQ_TABLE_END }
};
#undef OP
#define _BANIAS(cpuid, max, name) \
{ .cpu_id = cpuid, \
.model_name = "Intel(R) Pentium(R) M processor " name "MHz", \
.max_freq = (max)*1000, \
.op_points = banias_##max, \
}
#define BANIAS(max) _BANIAS(&cpu_ids[CPU_BANIAS], max, #max)
/* CPU models, their operating frequency range, and freq/voltage
operating points */
static struct cpu_model models[] =
{
_BANIAS(&cpu_ids[CPU_BANIAS], 900, " 900"),
BANIAS(1000),
BANIAS(1100),
BANIAS(1200),
BANIAS(1300),
BANIAS(1400),
BANIAS(1500),
BANIAS(1600),
BANIAS(1700),
/* NULL model_name is a wildcard */
{ &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },
{ &cpu_ids[CPU_DOTHAN_A2], NULL, 0, NULL },
{ &cpu_ids[CPU_DOTHAN_B0], NULL, 0, NULL },
{ &cpu_ids[CPU_MP4HT_D0], NULL, 0, NULL },
{ &cpu_ids[CPU_MP4HT_E0], NULL, 0, NULL },
{ NULL, }
};
#undef _BANIAS
#undef BANIAS
static int centrino_cpu_init_table(struct cpufreq_policy *policy)
{
struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
struct cpu_model *model;
for(model = models; model->cpu_id != NULL; model++)
if (centrino_verify_cpu_id(cpu, model->cpu_id) &&
(model->model_name == NULL ||
strcmp(cpu->x86_model_id, model->model_name) == 0))
break;
if (model->cpu_id == NULL) {
/* No match at all */
pr_debug("no support for CPU model \"%s\": "
"send /proc/cpuinfo to " MAINTAINER "\n",
cpu->x86_model_id);
return -ENOENT;
}
if (model->op_points == NULL) {
/* Matched a non-match */
pr_debug("no table support for CPU model \"%s\"\n",
cpu->x86_model_id);
pr_debug("try using the acpi-cpufreq driver\n");
return -ENOENT;
}
per_cpu(centrino_model, policy->cpu) = model;
pr_debug("found \"%s\": max frequency: %dkHz\n",
model->model_name, model->max_freq);
return 0;
}
#else
static inline int centrino_cpu_init_table(struct cpufreq_policy *policy)
{
return -ENODEV;
}
#endif /* CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE */
static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
const struct cpu_id *x)
{
if ((c->x86 == x->x86) &&
(c->x86_model == x->x86_model) &&
(c->x86_mask == x->x86_mask))
return 1;
return 0;
}
/* To be called only after centrino_model is initialized */
static unsigned extract_clock(unsigned msr, unsigned int cpu, int failsafe)
{
int i;
/*
* Extract clock in kHz from PERF_CTL value
* for centrino, as some DSDTs are buggy.
* Ideally, this can be done using the acpi_data structure.
*/
if ((per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_BANIAS]) ||
(per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_A1]) ||
(per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_B0])) {
msr = (msr >> 8) & 0xff;
return msr * 100000;
}
if ((!per_cpu(centrino_model, cpu)) ||
(!per_cpu(centrino_model, cpu)->op_points))
return 0;
msr &= 0xffff;
for (i = 0;
per_cpu(centrino_model, cpu)->op_points[i].frequency
!= CPUFREQ_TABLE_END;
i++) {
if (msr == per_cpu(centrino_model, cpu)->op_points[i].index)
return per_cpu(centrino_model, cpu)->
op_points[i].frequency;
}
if (failsafe)
return per_cpu(centrino_model, cpu)->op_points[i-1].frequency;
else
return 0;
}
/* Return the current CPU frequency in kHz */
static unsigned int get_cur_freq(unsigned int cpu)
{
unsigned l, h;
unsigned clock_freq;
rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h);
clock_freq = extract_clock(l, cpu, 0);
if (unlikely(clock_freq == 0)) {
/*
* On some CPUs, we can see transient MSR values (which are
* not present in _PSS), while CPU is doing some automatic
* P-state transition (like TM2). Get the last freq set
* in PERF_CTL.
*/
rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h);
clock_freq = extract_clock(l, cpu, 1);
}
return clock_freq;
}
static int centrino_cpu_init(struct cpufreq_policy *policy)
{
struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
unsigned freq;
unsigned l, h;
int ret;
int i;
/* Only Intel makes Enhanced Speedstep-capable CPUs */
if (cpu->x86_vendor != X86_VENDOR_INTEL ||
!cpu_has(cpu, X86_FEATURE_EST))
return -ENODEV;
if (cpu_has(cpu, X86_FEATURE_CONSTANT_TSC))
centrino_driver.flags |= CPUFREQ_CONST_LOOPS;
if (policy->cpu != 0)
return -ENODEV;
for (i = 0; i < N_IDS; i++)
if (centrino_verify_cpu_id(cpu, &cpu_ids[i]))
break;
if (i != N_IDS)
per_cpu(centrino_cpu, policy->cpu) = &cpu_ids[i];
if (!per_cpu(centrino_cpu, policy->cpu)) {
pr_debug("found unsupported CPU with "
"Enhanced SpeedStep: send /proc/cpuinfo to "
MAINTAINER "\n");
return -ENODEV;
}
if (centrino_cpu_init_table(policy)) {
return -ENODEV;
}
/* Check to see if Enhanced SpeedStep is enabled, and try to
enable it if not. */
rdmsr(MSR_IA32_MISC_ENABLE, l, h);
if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
l |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
pr_debug("trying to enable Enhanced SpeedStep (%x)\n", l);
wrmsr(MSR_IA32_MISC_ENABLE, l, h);
/* check to see if it stuck */
rdmsr(MSR_IA32_MISC_ENABLE, l, h);
if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
printk(KERN_INFO PFX
"couldn't enable Enhanced SpeedStep\n");
return -ENODEV;
}
}
freq = get_cur_freq(policy->cpu);
policy->cpuinfo.transition_latency = 10000;
/* 10uS transition latency */
policy->cur = freq;
pr_debug("centrino_cpu_init: cur=%dkHz\n", policy->cur);
ret = cpufreq_frequency_table_cpuinfo(policy,
per_cpu(centrino_model, policy->cpu)->op_points);
if (ret)
return (ret);
cpufreq_frequency_table_get_attr(
per_cpu(centrino_model, policy->cpu)->op_points, policy->cpu);
return 0;
}
static int centrino_cpu_exit(struct cpufreq_policy *policy)
{
unsigned int cpu = policy->cpu;
if (!per_cpu(centrino_model, cpu))
return -ENODEV;
cpufreq_frequency_table_put_attr(cpu);
per_cpu(centrino_model, cpu) = NULL;
return 0;
}
/**
* centrino_verify - verifies a new CPUFreq policy
* @policy: new policy
*
* Limit must be within this model's frequency range at least one
* border included.
*/
static int centrino_verify (struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy,
per_cpu(centrino_model, policy->cpu)->op_points);
}
/**
* centrino_setpolicy - set a new CPUFreq policy
* @policy: new policy
* @target_freq: the target frequency
* @relation: how that frequency relates to achieved frequency
* (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
*
* Sets a new CPUFreq policy.
*/
static int centrino_target (struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
unsigned int newstate = 0;
unsigned int msr, oldmsr = 0, h = 0, cpu = policy->cpu;
struct cpufreq_freqs freqs;
int retval = 0;
unsigned int j, k, first_cpu, tmp;
cpumask_var_t covered_cpus;
if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
return -ENOMEM;
if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
retval = -ENODEV;
goto out;
}
if (unlikely(cpufreq_frequency_table_target(policy,
per_cpu(centrino_model, cpu)->op_points,
target_freq,
relation,
&newstate))) {
retval = -EINVAL;
goto out;
}
first_cpu = 1;
for_each_cpu(j, policy->cpus) {
int good_cpu;
/* cpufreq holds the hotplug lock, so we are safe here */
if (!cpu_online(j))
continue;
/*
* Support for SMP systems.
* Make sure we are running on CPU that wants to change freq
*/
if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
good_cpu = cpumask_any_and(policy->cpus,
cpu_online_mask);
else
good_cpu = j;
if (good_cpu >= nr_cpu_ids) {
pr_debug("couldn't limit to CPUs in this domain\n");
retval = -EAGAIN;
if (first_cpu) {
/* We haven't started the transition yet. */
goto out;
}
break;
}
msr = per_cpu(centrino_model, cpu)->op_points[newstate].index;
if (first_cpu) {
rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
if (msr == (oldmsr & 0xffff)) {
pr_debug("no change needed - msr was and needs "
"to be %x\n", oldmsr);
retval = 0;
goto out;
}
freqs.old = extract_clock(oldmsr, cpu, 0);
freqs.new = extract_clock(msr, cpu, 0);
pr_debug("target=%dkHz old=%d new=%d msr=%04x\n",
target_freq, freqs.old, freqs.new, msr);
for_each_cpu(k, policy->cpus) {
if (!cpu_online(k))
continue;
freqs.cpu = k;
cpufreq_notify_transition(&freqs,
CPUFREQ_PRECHANGE);
}
first_cpu = 0;
/* all but 16 LSB are reserved, treat them with care */
oldmsr &= ~0xffff;
msr &= 0xffff;
oldmsr |= msr;
}
wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
break;
cpumask_set_cpu(j, covered_cpus);
}
for_each_cpu(k, policy->cpus) {
if (!cpu_online(k))
continue;
freqs.cpu = k;
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
}
if (unlikely(retval)) {
/*
* We have failed halfway through the frequency change.
* We have sent callbacks to policy->cpus and
* MSRs have already been written on coverd_cpus.
* Best effort undo..
*/
for_each_cpu(j, covered_cpus)
wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
tmp = freqs.new;
freqs.new = freqs.old;
freqs.old = tmp;
for_each_cpu(j, policy->cpus) {
if (!cpu_online(j))
continue;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
}
}
retval = 0;
out:
free_cpumask_var(covered_cpus);
return retval;
}
static struct freq_attr* centrino_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver centrino_driver = {
.name = "centrino", /* should be speedstep-centrino,
but there's a 16 char limit */
.init = centrino_cpu_init,
.exit = centrino_cpu_exit,
.verify = centrino_verify,
.target = centrino_target,
.get = get_cur_freq,
.attr = centrino_attr,
.owner = THIS_MODULE,
};
/**
* centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
*
* Initializes the Enhanced SpeedStep support. Returns -ENODEV on
* unsupported devices, -ENOENT if there's no voltage table for this
* particular CPU model, -EINVAL on problems during initiatization,
* and zero on success.
*
* This is quite picky. Not only does the CPU have to advertise the
* "est" flag in the cpuid capability flags, we look for a specific
* CPU model and stepping, and we need to have the exact model name in
* our voltage tables. That is, be paranoid about not releasing
* someone's valuable magic smoke.
*/
static int __init centrino_init(void)
{
struct cpuinfo_x86 *cpu = &cpu_data(0);
if (!cpu_has(cpu, X86_FEATURE_EST))
return -ENODEV;
return cpufreq_register_driver(¢rino_driver);
}
static void __exit centrino_exit(void)
{
cpufreq_unregister_driver(¢rino_driver);
}
MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
MODULE_LICENSE ("GPL");
late_initcall(centrino_init);
module_exit(centrino_exit);