// SPDX-License-Identifier: GPL-2.0-only
/*
* Based on documentation provided by Dave Jones. Thanks!
*
* 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/init.h>
#include <linux/cpufreq.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/timex.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <asm/cpu_device_id.h>
#include <asm/msr.h>
#include <asm/tsc.h>
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
#include <linux/acpi.h>
#include <acpi/processor.h>
#endif
#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;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
u32 bios_limit;
#endif
struct cpufreq_frequency_table freq_table[];
};
static struct eps_cpu_data *eps_cpu[NR_CPUS];
/* Module parameters */
static int freq_failsafe_off;
static int voltage_failsafe_off;
static int set_max_voltage;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
static int ignore_acpi_limit;
static struct acpi_processor_performance *eps_acpi_cpu_perf;
/* Minimum necessary to get acpi_processor_get_bios_limit() working */
static int eps_acpi_init(void)
{
eps_acpi_cpu_perf = kzalloc(sizeof(*eps_acpi_cpu_perf),
GFP_KERNEL);
if (!eps_acpi_cpu_perf)
return -ENOMEM;
if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
GFP_KERNEL)) {
kfree(eps_acpi_cpu_perf);
eps_acpi_cpu_perf = NULL;
return -ENOMEM;
}
if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
kfree(eps_acpi_cpu_perf);
eps_acpi_cpu_perf = NULL;
return -EIO;
}
return 0;
}
static int eps_acpi_exit(struct cpufreq_policy *policy)
{
if (eps_acpi_cpu_perf) {
acpi_processor_unregister_performance(0);
free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
kfree(eps_acpi_cpu_perf);
eps_acpi_cpu_perf = NULL;
}
return 0;
}
#endif
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,
struct cpufreq_policy *policy,
u32 dest_state)
{
u32 lo, hi;
int i;
/* 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)) {
return -ENODEV;
}
}
/* 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)) {
return -ENODEV;
}
} while (lo & ((1 << 16) | (1 << 17)));
#ifdef DEBUG
{
u8 current_multiplier, current_voltage;
/* Print voltage and multiplier */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
current_voltage = lo & 0xff;
pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
current_multiplier = (lo >> 8) & 0xff;
pr_info("Current multiplier = %d\n", current_multiplier);
}
#endif
return 0;
}
static int eps_target(struct cpufreq_policy *policy, unsigned int index)
{
struct eps_cpu_data *centaur;
unsigned int cpu = policy->cpu;
unsigned int dest_state;
int ret;
if (unlikely(eps_cpu[cpu] == NULL))
return -ENODEV;
centaur = eps_cpu[cpu];
/* Make frequency transition */
dest_state = centaur->freq_table[index].driver_data & 0xffff;
ret = eps_set_state(centaur, policy, dest_state);
if (ret)
pr_err("Timeout!\n");
return ret;
}
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 states;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
unsigned int limit;
#endif
if (policy->cpu != 0)
return -ENODEV;
/* Check brand */
pr_info("Detected VIA ");
switch (c->x86_model) {
case 10:
rdmsr(0x1153, lo, hi);
brand = (((lo >> 2) ^ lo) >> 18) & 3;
pr_cont("Model A ");
break;
case 13:
rdmsr(0x1154, lo, hi);
brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
pr_cont("Model D ");
break;
}
switch (brand) {
case EPS_BRAND_C7M:
pr_cont("C7-M\n");
break;
case EPS_BRAND_C7:
pr_cont("C7\n");
break;
case EPS_BRAND_EDEN:
pr_cont("Eden\n");
break;
case EPS_BRAND_C7D:
pr_cont("C7-D\n");
break;
case EPS_BRAND_C3:
pr_cont("C3\n");
return -ENODEV;
}
/* Enable Enhanced PowerSaver */
rdmsrl(MSR_IA32_MISC_ENABLE, val);
if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
wrmsrl(MSR_IA32_MISC_ENABLE, val);
/* Can be locked at 0 */
rdmsrl(MSR_IA32_MISC_ENABLE, val);
if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
pr_info("Can't enable Enhanced PowerSaver\n");
return -ENODEV;
}
}
/* Print voltage and multiplier */
rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
current_voltage = lo & 0xff;
pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
current_multiplier = (lo >> 8) & 0xff;
pr_info("Current multiplier = %d\n", current_multiplier);
/* Print limits */
max_voltage = hi & 0xff;
pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
max_multiplier = (hi >> 8) & 0xff;
pr_info("Highest multiplier = %d\n", max_multiplier);
min_voltage = (hi >> 16) & 0xff;
pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
min_multiplier = (hi >> 24) & 0xff;
pr_info("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
|| current_voltage < min_voltage
|| current_voltage > max_voltage)
return -EINVAL;
/* Check for systems using underclocked CPU */
if (!freq_failsafe_off && max_multiplier != current_multiplier) {
pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
pr_info("You can use freq_failsafe_off option to disable this check.\n");
return -EINVAL;
}
if (!voltage_failsafe_off && max_voltage != current_voltage) {
pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
pr_info("You can use voltage_failsafe_off option to disable this check.\n");
return -EINVAL;
}
/* Calc FSB speed */
fsb = cpu_khz / current_multiplier;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
/* Check for ACPI processor speed limit */
if (!ignore_acpi_limit && !eps_acpi_init()) {
if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
pr_info("ACPI limit %u.%uGHz\n",
limit/1000000,
(limit%1000000)/10000);
eps_acpi_exit(policy);
/* Check if max_multiplier is in BIOS limits */
if (limit && max_multiplier * fsb > limit) {
pr_info("Aborting\n");
return -EINVAL;
}
}
}
#endif
/* Allow user to set lower maximum voltage then that reported
* by processor */
if (brand == EPS_BRAND_C7M && set_max_voltage) {
u32 v;
/* Change mV to something hardware can use */
v = (set_max_voltage - 700) / 16;
/* Check if voltage is within limits */
if (v >= min_voltage && v <= max_voltage) {
pr_info("Setting %dmV as maximum\n", v * 16 + 700);
max_voltage = v;
}
}
/* 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(struct_size(centaur, freq_table, states + 1),
GFP_KERNEL);
if (!centaur)
return -ENOMEM;
eps_cpu[0] = centaur;
/* Copy basic values */
centaur->fsb = fsb;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
centaur->bios_limit = limit;
#endif
/* 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].driver_data = (min_multiplier << 8) | min_voltage;
f_table[1].frequency = fsb * max_multiplier;
f_table[1].driver_data = (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].driver_data = (i << 8) | voltage;
k++;
}
f_table[k].frequency = CPUFREQ_TABLE_END;
}
policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
policy->freq_table = ¢aur->freq_table[0];
return 0;
}
static void eps_cpu_exit(struct cpufreq_policy *policy)
{
unsigned int cpu = policy->cpu;
/* Bye */
kfree(eps_cpu[cpu]);
eps_cpu[cpu] = NULL;
}
static struct cpufreq_driver eps_driver = {
.verify = cpufreq_generic_frequency_table_verify,
.target_index = eps_target,
.init = eps_cpu_init,
.exit = eps_cpu_exit,
.get = eps_get,
.name = "e_powersaver",
.attr = cpufreq_generic_attr,
};
/* This driver will work only on Centaur C7 processors with
* Enhanced SpeedStep/PowerSaver registers */
static const struct x86_cpu_id eps_cpu_id[] = {
X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_EST, NULL),
{}
};
MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
static int __init eps_init(void)
{
if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
return -ENODEV;
if (cpufreq_register_driver(&eps_driver))
return -EINVAL;
return 0;
}
static void __exit eps_exit(void)
{
cpufreq_unregister_driver(&eps_driver);
}
/* Allow user to overclock his machine or to change frequency to higher after
* unloading module */
module_param(freq_failsafe_off, int, 0644);
MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
module_param(voltage_failsafe_off, int, 0644);
MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
module_param(ignore_acpi_limit, int, 0644);
MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
#endif
module_param(set_max_voltage, int, 0644);
MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
MODULE_AUTHOR("Rafal Bilski <[email protected]>");
MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
MODULE_LICENSE("GPL");
module_init(eps_init);
module_exit(eps_exit);
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