diff options
Diffstat (limited to 'drivers/cpufreq/amd_freq_sensitivity.c')
| -rw-r--r-- | drivers/cpufreq/amd_freq_sensitivity.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/drivers/cpufreq/amd_freq_sensitivity.c b/drivers/cpufreq/amd_freq_sensitivity.c new file mode 100644 index 000000000000..f6b79ab0070b --- /dev/null +++ b/drivers/cpufreq/amd_freq_sensitivity.c @@ -0,0 +1,148 @@ +/* + * amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias + * for the ondemand governor. + * + * Copyright (C) 2013 Advanced Micro Devices, Inc. + * + * Author: Jacob Shin <jacob.shin@amd.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/percpu-defs.h> +#include <linux/init.h> +#include <linux/mod_devicetable.h> + +#include <asm/msr.h> +#include <asm/cpufeature.h> + +#include "cpufreq_governor.h" + +#define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL 0xc0010080 +#define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE 0xc0010081 +#define CLASS_CODE_SHIFT 56 +#define POWERSAVE_BIAS_MAX 1000 +#define POWERSAVE_BIAS_DEF 400 + +struct cpu_data_t { + u64 actual; + u64 reference; + unsigned int freq_prev; +}; + +static DEFINE_PER_CPU(struct cpu_data_t, cpu_data); + +static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy, + unsigned int freq_next, + unsigned int relation) +{ + int sensitivity; + long d_actual, d_reference; + struct msr actual, reference; + struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu); + struct dbs_data *od_data = policy->governor_data; + struct od_dbs_tuners *od_tuners = od_data->tuners; + struct od_cpu_dbs_info_s *od_info = + od_data->cdata->get_cpu_dbs_info_s(policy->cpu); + + if (!od_info->freq_table) + return freq_next; + + rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, + &actual.l, &actual.h); + rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE, + &reference.l, &reference.h); + actual.h &= 0x00ffffff; + reference.h &= 0x00ffffff; + + /* counter wrapped around, so stay on current frequency */ + if (actual.q < data->actual || reference.q < data->reference) { + freq_next = policy->cur; + goto out; + } + + d_actual = actual.q - data->actual; + d_reference = reference.q - data->reference; + + /* divide by 0, so stay on current frequency as well */ + if (d_reference == 0) { + freq_next = policy->cur; + goto out; + } + + sensitivity = POWERSAVE_BIAS_MAX - + (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference); + + clamp(sensitivity, 0, POWERSAVE_BIAS_MAX); + + /* this workload is not CPU bound, so choose a lower freq */ + if (sensitivity < od_tuners->powersave_bias) { + if (data->freq_prev == policy->cur) + freq_next = policy->cur; + + if (freq_next > policy->cur) + freq_next = policy->cur; + else if (freq_next < policy->cur) + freq_next = policy->min; + else { + unsigned int index; + + cpufreq_frequency_table_target(policy, + od_info->freq_table, policy->cur - 1, + CPUFREQ_RELATION_H, &index); + freq_next = od_info->freq_table[index].frequency; + } + + data->freq_prev = freq_next; + } else + data->freq_prev = 0; + +out: + data->actual = actual.q; + data->reference = reference.q; + return freq_next; +} + +static int __init amd_freq_sensitivity_init(void) +{ + u64 val; + + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) + return -ENODEV; + + if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK)) + return -ENODEV; + + if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val)) + return -ENODEV; + + if (!(val >> CLASS_CODE_SHIFT)) + return -ENODEV; + + od_register_powersave_bias_handler(amd_powersave_bias_target, + POWERSAVE_BIAS_DEF); + return 0; +} +late_initcall(amd_freq_sensitivity_init); + +static void __exit amd_freq_sensitivity_exit(void) +{ + od_unregister_powersave_bias_handler(); +} +module_exit(amd_freq_sensitivity_exit); + +static const struct x86_cpu_id amd_freq_sensitivity_ids[] = { + X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK), + {} +}; +MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids); + +MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>"); +MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for " + "the ondemand governor."); +MODULE_LICENSE("GPL"); |