diff options
Diffstat (limited to 'drivers/cpufreq/e_powersaver.c')
| -rw-r--r-- | drivers/cpufreq/e_powersaver.c | 424 |
1 files changed, 424 insertions, 0 deletions
diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c new file mode 100644 index 000000000..ab93bce8a --- /dev/null +++ b/drivers/cpufreq/e_powersaver.c @@ -0,0 +1,424 @@ +// 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 int eps_cpu_exit(struct cpufreq_policy *policy) +{ + unsigned int cpu = policy->cpu; + + /* Bye */ + kfree(eps_cpu[cpu]); + eps_cpu[cpu] = NULL; + return 0; +} + +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 <rafalbilski@interia.pl>"); +MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's."); +MODULE_LICENSE("GPL"); + +module_init(eps_init); +module_exit(eps_exit); |