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