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");