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
 27static struct cpufreq_frequency_table *freq_table;
 28static struct sfi_freq_table_entry *sfi_cpufreq_array;
 29static int num_freq_table_entries;
 30
 31static 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
 55static 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
 71static 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	policy->freq_table = freq_table;
 76
 77	return 0;
 78}
 79
 80static struct cpufreq_driver sfi_cpufreq_driver = {
 81	.flags		= CPUFREQ_CONST_LOOPS,
 82	.verify		= cpufreq_generic_frequency_table_verify,
 83	.target_index	= sfi_cpufreq_target,
 84	.init		= sfi_cpufreq_cpu_init,
 85	.name		= "sfi-cpufreq",
 86	.attr		= cpufreq_generic_attr,
 87};
 88
 89static int __init sfi_cpufreq_init(void)
 90{
 91	int ret, i;
 92
 93	/* parse the freq table from SFI */
 94	ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq);
 95	if (ret)
 96		return ret;
 97
 98	freq_table = kzalloc(sizeof(*freq_table) *
 99			(num_freq_table_entries + 1), GFP_KERNEL);
100	if (!freq_table) {
101		ret = -ENOMEM;
102		goto err_free_array;
103	}
104
105	for (i = 0; i < num_freq_table_entries; i++) {
106		freq_table[i].driver_data = i;
107		freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000;
108	}
109	freq_table[i].frequency = CPUFREQ_TABLE_END;
110
111	ret = cpufreq_register_driver(&sfi_cpufreq_driver);
112	if (ret)
113		goto err_free_tbl;
114
115	return ret;
116
117err_free_tbl:
118	kfree(freq_table);
119err_free_array:
120	kfree(sfi_cpufreq_array);
121	return ret;
122}
123late_initcall(sfi_cpufreq_init);
124
125static void __exit sfi_cpufreq_exit(void)
126{
127	cpufreq_unregister_driver(&sfi_cpufreq_driver);
128	kfree(freq_table);
129	kfree(sfi_cpufreq_array);
130}
131module_exit(sfi_cpufreq_exit);
132
133MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>");
134MODULE_DESCRIPTION("SFI Performance-States Driver");
135MODULE_LICENSE("GPL");