LXR linux/drivers/cpufreq/sfi-cpufreq.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  SFI Performance States Driver
   4 *
   5 *  Author: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>
   6 *  Author: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
   7 */
   8
   9#include <linux/cpufreq.h>
  10#include <linux/init.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/sfi.h>
  14#include <linux/slab.h>
  15#include <linux/smp.h>
  16
  17#include <asm/msr.h>
  18
  19static struct cpufreq_frequency_table *freq_table;
  20static struct sfi_freq_table_entry *sfi_cpufreq_array;
  21static int num_freq_table_entries;
  22
  23static int sfi_parse_freq(struct sfi_table_header *table)
  24{
  25        struct sfi_table_simple *sb;
  26        struct sfi_freq_table_entry *pentry;
  27        int totallen;
  28
  29        sb = (struct sfi_table_simple *)table;
  30        num_freq_table_entries = SFI_GET_NUM_ENTRIES(sb,
  31                        struct sfi_freq_table_entry);
  32        if (num_freq_table_entries <= 1) {
  33                pr_err("No p-states discovered\n");
  34                return -ENODEV;
  35        }
  36
  37        pentry = (struct sfi_freq_table_entry *)sb->pentry;
  38        totallen = num_freq_table_entries * sizeof(*pentry);
  39
  40        sfi_cpufreq_array = kmemdup(pentry, totallen, GFP_KERNEL);
  41        if (!sfi_cpufreq_array)
  42                return -ENOMEM;
  43
  44        return 0;
  45}
  46
  47static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index)
  48{
  49        unsigned int next_perf_state = 0; /* Index into perf table */
  50        u32 lo, hi;
  51
  52        next_perf_state = policy->freq_table[index].driver_data;
  53
  54        rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi);
  55        lo = (lo & ~INTEL_PERF_CTL_MASK) |
  56                ((u32) sfi_cpufreq_array[next_perf_state].ctrl_val &
  57                INTEL_PERF_CTL_MASK);
  58        wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi);
  59
  60        return 0;
  61}
  62
  63static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy)
  64{
  65        policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
  66        policy->cpuinfo.transition_latency = 100000;    /* 100us */
  67        policy->freq_table = freq_table;
  68
  69        return 0;
  70}
  71
  72static struct cpufreq_driver sfi_cpufreq_driver = {
  73        .flags          = CPUFREQ_CONST_LOOPS,
  74        .verify         = cpufreq_generic_frequency_table_verify,
  75        .target_index   = sfi_cpufreq_target,
  76        .init           = sfi_cpufreq_cpu_init,
  77        .name           = "sfi-cpufreq",
  78        .attr           = cpufreq_generic_attr,
  79};
  80
  81static int __init sfi_cpufreq_init(void)
  82{
  83        int ret, i;
  84
  85        /* parse the freq table from SFI */
  86        ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq);
  87        if (ret)
  88                return ret;
  89
  90        freq_table = kcalloc(num_freq_table_entries + 1, sizeof(*freq_table),
  91                             GFP_KERNEL);
  92        if (!freq_table) {
  93                ret = -ENOMEM;
  94                goto err_free_array;
  95        }
  96
  97        for (i = 0; i < num_freq_table_entries; i++) {
  98                freq_table[i].driver_data = i;
  99                freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000;
 100        }
 101        freq_table[i].frequency = CPUFREQ_TABLE_END;
 102
 103        ret = cpufreq_register_driver(&sfi_cpufreq_driver);
 104        if (ret)
 105                goto err_free_tbl;
 106
 107        return ret;
 108
 109err_free_tbl:
 110        kfree(freq_table);
 111err_free_array:
 112        kfree(sfi_cpufreq_array);
 113        return ret;
 114}
 115late_initcall(sfi_cpufreq_init);
 116
 117static void __exit sfi_cpufreq_exit(void)
 118{
 119        cpufreq_unregister_driver(&sfi_cpufreq_driver);
 120        kfree(freq_table);
 121        kfree(sfi_cpufreq_array);
 122}
 123module_exit(sfi_cpufreq_exit);
 124
 125MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>");
 126MODULE_DESCRIPTION("SFI Performance-States Driver");
 127MODULE_LICENSE("GPL");
 128