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DEFINITIONS
This source file includes following definitions.
- eps_get
- eps_set_state
- eps_target
- eps_verify
- eps_cpu_init
- eps_cpu_exit
- eps_init
- eps_exit
/*
* Based on documentation provided by Dave Jones. Thanks!
*
* Licensed under the terms of the GNU GPL License version 2.
*
* BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <asm/msr.h>
#include <asm/tsc.h>
#include <asm/timex.h>
#include <asm/io.h>
#include <asm/delay.h>
#define EPS_BRAND_C7M 0
#define EPS_BRAND_C7 1
#define EPS_BRAND_EDEN 2
#define EPS_BRAND_C3 3
#define EPS_BRAND_C7D 4
struct eps_cpu_data {
u32 fsb;
struct cpufreq_frequency_table freq_table[];
};
static struct eps_cpu_data *eps_cpu[NR_CPUS];
static unsigned int eps_get(unsigned int cpu)
{
struct eps_cpu_data *centaur;
u32 lo, hi;
if (cpu)
return 0;
centaur = eps_cpu[cpu];
if (centaur == NULL)
return 0;
/* Return current frequency */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
return centaur->fsb * ((lo >> 8) & 0xff);
}
static int eps_set_state(struct eps_cpu_data *centaur,
unsigned int cpu,
u32 dest_state)
{
struct cpufreq_freqs freqs;
u32 lo, hi;
int err = 0;
int i;
freqs.old = eps_get(cpu);
freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
freqs.cpu = cpu;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
/* Wait while CPU is busy */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
i = 0;
while (lo & ((1 << 16) | (1 << 17))) {
udelay(16);
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
i++;
if (unlikely(i > 64)) {
err = -ENODEV;
goto postchange;
}
}
/* Set new multiplier and voltage */
wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
/* Wait until transition end */
i = 0;
do {
udelay(16);
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
i++;
if (unlikely(i > 64)) {
err = -ENODEV;
goto postchange;
}
} while (lo & ((1 << 16) | (1 << 17)));
/* Return current frequency */
postchange:
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
#ifdef DEBUG
{
u8 current_multiplier, current_voltage;
/* Print voltage and multiplier */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
current_voltage = lo & 0xff;
printk(KERN_INFO "eps: Current voltage = %dmV\n",
current_voltage * 16 + 700);
current_multiplier = (lo >> 8) & 0xff;
printk(KERN_INFO "eps: Current multiplier = %d\n",
current_multiplier);
}
#endif
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return err;
}
static int eps_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
struct eps_cpu_data *centaur;
unsigned int newstate = 0;
unsigned int cpu = policy->cpu;
unsigned int dest_state;
int ret;
if (unlikely(eps_cpu[cpu] == NULL))
return -ENODEV;
centaur = eps_cpu[cpu];
if (unlikely(cpufreq_frequency_table_target(policy,
&eps_cpu[cpu]->freq_table[0],
target_freq,
relation,
&newstate))) {
return -EINVAL;
}
/* Make frequency transition */
dest_state = centaur->freq_table[newstate].index & 0xffff;
ret = eps_set_state(centaur, cpu, dest_state);
if (ret)
printk(KERN_ERR "eps: Timeout!\n");
return ret;
}
static int eps_verify(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy,
&eps_cpu[policy->cpu]->freq_table[0]);
}
static int eps_cpu_init(struct cpufreq_policy *policy)
{
unsigned int i;
u32 lo, hi;
u64 val;
u8 current_multiplier, current_voltage;
u8 max_multiplier, max_voltage;
u8 min_multiplier, min_voltage;
u8 brand = 0;
u32 fsb;
struct eps_cpu_data *centaur;
struct cpuinfo_x86 *c = &cpu_data(0);
struct cpufreq_frequency_table *f_table;
int k, step, voltage;
int ret;
int states;
if (policy->cpu != 0)
return -ENODEV;
/* Check brand */
printk(KERN_INFO "eps: Detected VIA ");
switch (c->x86_model) {
case 10:
rdmsr(0x1153, lo, hi);
brand = (((lo >> 2) ^ lo) >> 18) & 3;
printk(KERN_CONT "Model A ");
break;
case 13:
rdmsr(0x1154, lo, hi);
brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
printk(KERN_CONT "Model D ");
break;
}
switch(brand) {
case EPS_BRAND_C7M:
printk(KERN_CONT "C7-M\n");
break;
case EPS_BRAND_C7:
printk(KERN_CONT "C7\n");
break;
case EPS_BRAND_EDEN:
printk(KERN_CONT "Eden\n");
break;
case EPS_BRAND_C7D:
printk(KERN_CONT "C7-D\n");
break;
case EPS_BRAND_C3:
printk(KERN_CONT "C3\n");
return -ENODEV;
break;
}
/* Enable Enhanced PowerSaver */
rdmsrl(MSR_IA32_MISC_ENABLE, val);
if (!(val & 1 << 16)) {
val |= 1 << 16;
wrmsrl(MSR_IA32_MISC_ENABLE, val);
/* Can be locked at 0 */
rdmsrl(MSR_IA32_MISC_ENABLE, val);
if (!(val & 1 << 16)) {
printk(KERN_INFO "eps: Can't enable Enhanced PowerSaver\n");
return -ENODEV;
}
}
/* Print voltage and multiplier */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
current_voltage = lo & 0xff;
printk(KERN_INFO "eps: Current voltage = %dmV\n", current_voltage * 16 + 700);
current_multiplier = (lo >> 8) & 0xff;
printk(KERN_INFO "eps: Current multiplier = %d\n", current_multiplier);
/* Print limits */
max_voltage = hi & 0xff;
printk(KERN_INFO "eps: Highest voltage = %dmV\n", max_voltage * 16 + 700);
max_multiplier = (hi >> 8) & 0xff;
printk(KERN_INFO "eps: Highest multiplier = %d\n", max_multiplier);
min_voltage = (hi >> 16) & 0xff;
printk(KERN_INFO "eps: Lowest voltage = %dmV\n", min_voltage * 16 + 700);
min_multiplier = (hi >> 24) & 0xff;
printk(KERN_INFO "eps: Lowest multiplier = %d\n", min_multiplier);
/* Sanity checks */
if (current_multiplier == 0 || max_multiplier == 0
|| min_multiplier == 0)
return -EINVAL;
if (current_multiplier > max_multiplier
|| max_multiplier <= min_multiplier)
return -EINVAL;
if (current_voltage > 0x1f || max_voltage > 0x1f)
return -EINVAL;
if (max_voltage < min_voltage)
return -EINVAL;
/* Calc FSB speed */
fsb = cpu_khz / current_multiplier;
/* Calc number of p-states supported */
if (brand == EPS_BRAND_C7M)
states = max_multiplier - min_multiplier + 1;
else
states = 2;
/* Allocate private data and frequency table for current cpu */
centaur = kzalloc(sizeof(struct eps_cpu_data)
+ (states + 1) * sizeof(struct cpufreq_frequency_table),
GFP_KERNEL);
if (!centaur)
return -ENOMEM;
eps_cpu[0] = centaur;
/* Copy basic values */
centaur->fsb = fsb;
/* Fill frequency and MSR value table */
f_table = ¢aur->freq_table[0];
if (brand != EPS_BRAND_C7M) {
f_table[0].frequency = fsb * min_multiplier;
f_table[0].index = (min_multiplier << 8) | min_voltage;
f_table[1].frequency = fsb * max_multiplier;
f_table[1].index = (max_multiplier << 8) | max_voltage;
f_table[2].frequency = CPUFREQ_TABLE_END;
} else {
k = 0;
step = ((max_voltage - min_voltage) * 256)
/ (max_multiplier - min_multiplier);
for (i = min_multiplier; i <= max_multiplier; i++) {
voltage = (k * step) / 256 + min_voltage;
f_table[k].frequency = fsb * i;
f_table[k].index = (i << 8) | voltage;
k++;
}
f_table[k].frequency = CPUFREQ_TABLE_END;
}
policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
policy->cur = fsb * current_multiplier;
ret = cpufreq_frequency_table_cpuinfo(policy, ¢aur->freq_table[0]);
if (ret) {
kfree(centaur);
return ret;
}
cpufreq_frequency_table_get_attr(¢aur->freq_table[0], policy->cpu);
return 0;
}
static int eps_cpu_exit(struct cpufreq_policy *policy)
{
unsigned int cpu = policy->cpu;
struct eps_cpu_data *centaur;
u32 lo, hi;
if (eps_cpu[cpu] == NULL)
return -ENODEV;
centaur = eps_cpu[cpu];
/* Get max frequency */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
/* Set max frequency */
eps_set_state(centaur, cpu, hi & 0xffff);
/* Bye */
cpufreq_frequency_table_put_attr(policy->cpu);
kfree(eps_cpu[cpu]);
eps_cpu[cpu] = NULL;
return 0;
}
static struct freq_attr* eps_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver eps_driver = {
.verify = eps_verify,
.target = eps_target,
.init = eps_cpu_init,
.exit = eps_cpu_exit,
.get = eps_get,
.name = "e_powersaver",
.owner = THIS_MODULE,
.attr = eps_attr,
};
static int __init eps_init(void)
{
struct cpuinfo_x86 *c = &cpu_data(0);
/* This driver will work only on Centaur C7 processors with
* Enhanced SpeedStep/PowerSaver registers */
if (c->x86_vendor != X86_VENDOR_CENTAUR
|| c->x86 != 6 || c->x86_model < 10)
return -ENODEV;
if (!cpu_has(c, X86_FEATURE_EST))
return -ENODEV;
if (cpufreq_register_driver(&eps_driver))
return -EINVAL;
return 0;
}
static void __exit eps_exit(void)
{
cpufreq_unregister_driver(&eps_driver);
}
MODULE_AUTHOR("Rafał Bilski <rafalbilski@interia.pl>");
MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
MODULE_LICENSE("GPL");
module_init(eps_init);
module_exit(eps_exit);