drivers/cpufreq/sfi-cpufreq.c

   1 /*
   2  *  SFI Performance States Driver
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License.
   7  *
   8  *  This program is distributed in the hope that it will be useful, but
   9  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  *  General Public License for more details.
  12  *
  13  *  Author: Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>
  14  *  Author: Srinidhi Kasagar <srinidhi.kasagar@intel.com>
  15  */
  16
  17 #include <linux/cpufreq.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/sfi.h>
  22 #include <linux/slab.h>
  23 #include <linux/smp.h>
  24
  25 #include <asm/msr.h>
  26
  27 static struct cpufreq_frequency_table *freq_table;
  28 static struct sfi_freq_table_entry *sfi_cpufreq_array;
  29 static int num_freq_table_entries;
  30
  31 static int sfi_parse_freq(struct sfi_table_header *table)
  32 {
  33         struct sfi_table_simple *sb;
  34         struct sfi_freq_table_entry *pentry;
  35         int totallen;
  36
  37         sb = (struct sfi_table_simple *)table;
  38         num_freq_table_entries = SFI_GET_NUM_ENTRIES(sb,
  39                         struct sfi_freq_table_entry);
  40         if (num_freq_table_entries <= 1) {
  41                 pr_err("No p-states discovered\n");
  42                 return -ENODEV;
  43         }
  44
  45         pentry = (struct sfi_freq_table_entry *)sb->pentry;
  46         totallen = num_freq_table_entries * sizeof(*pentry);
  47
  48         sfi_cpufreq_array = kmemdup(pentry, totallen, GFP_KERNEL);
  49         if (!sfi_cpufreq_array)
  50                 return -ENOMEM;
  51
  52         return 0;
  53 }
  54
  55 static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index)
  56 {
  57         unsigned int next_perf_state = 0; /* Index into perf table */
  58         u32 lo, hi;
  59
  60         next_perf_state = policy->freq_table[index].driver_data;
  61
  62         rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi);
  63         lo = (lo & ~INTEL_PERF_CTL_MASK) |
  64                 ((u32) sfi_cpufreq_array[next_perf_state].ctrl_val &
  65                 INTEL_PERF_CTL_MASK);
  66         wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi);
  67
  68         return 0;
  69 }
  70
  71 static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy)
  72 {
  73         policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
  74         policy->cpuinfo.transition_latency = 100000;    /* 100us */
  75
  76         return cpufreq_table_validate_and_show(policy, freq_table);
  77 }
  78
  79 static struct cpufreq_driver sfi_cpufreq_driver = {
  80         .flags          = CPUFREQ_CONST_LOOPS,
  81         .verify         = cpufreq_generic_frequency_table_verify,
  82         .target_index   = sfi_cpufreq_target,
  83         .init           = sfi_cpufreq_cpu_init,
  84         .name           = "sfi-cpufreq",
  85         .attr           = cpufreq_generic_attr,
  86 };
  87
  88 static int __init sfi_cpufreq_init(void)
  89 {
  90         int ret, i;
  91
  92         /* parse the freq table from SFI */
  93         ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq);
  94         if (ret)
  95                 return ret;
  96
  97         freq_table = kzalloc(sizeof(*freq_table) *
  98                         (num_freq_table_entries + 1), GFP_KERNEL);
  99         if (!freq_table) {
 100                 ret = -ENOMEM;
 101                 goto err_free_array;
 102         }
 103
 104         for (i = 0; i < num_freq_table_entries; i++) {
 105                 freq_table[i].driver_data = i;
 106                 freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000;
 107         }
 108         freq_table[i].frequency = CPUFREQ_TABLE_END;
 109
 110         ret = cpufreq_register_driver(&sfi_cpufreq_driver);
 111         if (ret)
 112                 goto err_free_tbl;
 113
 114         return ret;
 115
 116 err_free_tbl:
 117         kfree(freq_table);
 118 err_free_array:
 119         kfree(sfi_cpufreq_array);
 120         return ret;
 121 }
 122 late_initcall(sfi_cpufreq_init);
 123
 124 static void __exit sfi_cpufreq_exit(void)
 125 {
 126         cpufreq_unregister_driver(&sfi_cpufreq_driver);
 127         kfree(freq_table);
 128         kfree(sfi_cpufreq_array);
 129 }
 130 module_exit(sfi_cpufreq_exit);
 131
 132 MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>");
 133 MODULE_DESCRIPTION("SFI Performance-States Driver");
 134 MODULE_LICENSE("GPL");