in e_powersaver.c [172:361]
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;
}