// SPDX-License-Identifier: GPL-2.0-only /* * SFI Performance States Driver * * Author: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com> * Author: Srinidhi Kasagar <srinidhi.kasagar@intel.com> */ #include <linux/cpufreq.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/sfi.h> #include <linux/slab.h> #include <linux/smp.h> #include <asm/msr.h> static struct cpufreq_frequency_table *freq_table; static struct sfi_freq_table_entry *sfi_cpufreq_array; static int num_freq_table_entries; static int sfi_parse_freq(struct sfi_table_header *table) { struct sfi_table_simple *sb; struct sfi_freq_table_entry *pentry; int totallen; sb = (struct sfi_table_simple *)table; num_freq_table_entries = SFI_GET_NUM_ENTRIES(sb, struct sfi_freq_table_entry); if (num_freq_table_entries <= 1) { pr_err("No p-states discovered\n"); return -ENODEV; } pentry = (struct sfi_freq_table_entry *)sb->pentry; totallen = num_freq_table_entries * sizeof(*pentry); sfi_cpufreq_array = kmemdup(pentry, totallen, GFP_KERNEL); if (!sfi_cpufreq_array) return -ENOMEM; return 0; } static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index) { unsigned int next_perf_state = 0; /* Index into perf table */ u32 lo, hi; next_perf_state = policy->freq_table[index].driver_data; rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi); lo = (lo & ~INTEL_PERF_CTL_MASK) | ((u32) sfi_cpufreq_array[next_perf_state].ctrl_val & INTEL_PERF_CTL_MASK); wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi); return 0; } static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy) { policy->shared_type = CPUFREQ_SHARED_TYPE_HW; policy->cpuinfo.transition_latency = 100000; /* 100us */ policy->freq_table = freq_table; return 0; } static struct cpufreq_driver sfi_cpufreq_driver = { .flags = CPUFREQ_CONST_LOOPS, .verify = cpufreq_generic_frequency_table_verify, .target_index = sfi_cpufreq_target, .init = sfi_cpufreq_cpu_init, .name = "sfi-cpufreq", .attr = cpufreq_generic_attr, }; static int __init sfi_cpufreq_init(void) { int ret, i; /* parse the freq table from SFI */ ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq); if (ret) return ret; freq_table = kcalloc(num_freq_table_entries + 1, sizeof(*freq_table), GFP_KERNEL); if (!freq_table) { ret = -ENOMEM; goto err_free_array; } for (i = 0; i < num_freq_table_entries; i++) { freq_table[i].driver_data = i; freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000; } freq_table[i].frequency = CPUFREQ_TABLE_END; ret = cpufreq_register_driver(&sfi_cpufreq_driver); if (ret) goto err_free_tbl; return ret; err_free_tbl: kfree(freq_table); err_free_array: kfree(sfi_cpufreq_array); return ret; } late_initcall(sfi_cpufreq_init); static void __exit sfi_cpufreq_exit(void) { cpufreq_unregister_driver(&sfi_cpufreq_driver); kfree(freq_table); kfree(sfi_cpufreq_array); } module_exit(sfi_cpufreq_exit); MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>"); MODULE_DESCRIPTION("SFI Performance-States Driver"); MODULE_LICENSE("GPL");