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
27struct 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 = kzalloc(totallen, GFP_KERNEL);
49	if (!sfi_cpufreq_array)
50		return -ENOMEM;
51
52	memcpy(sfi_cpufreq_array, pentry, totallen);
53
54	return 0;
55}
56
57static int sfi_cpufreq_target(struct cpufreq_policy *policy, unsigned int index)
58{
59	unsigned int next_perf_state = 0; /* Index into perf table */
60	u32 lo, hi;
61
62	next_perf_state = policy->freq_table[index].driver_data;
63
64	rdmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, &lo, &hi);
65	lo = (lo & ~INTEL_PERF_CTL_MASK) |
66		((u32) sfi_cpufreq_array[next_perf_state].ctrl_val &
67		INTEL_PERF_CTL_MASK);
68	wrmsr_on_cpu(policy->cpu, MSR_IA32_PERF_CTL, lo, hi);
69
70	return 0;
71}
72
73static int sfi_cpufreq_cpu_init(struct cpufreq_policy *policy)
74{
75	policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
76	policy->cpuinfo.transition_latency = 100000;	/* 100us */
77
78	return cpufreq_table_validate_and_show(policy, freq_table);
79}
80
81static struct cpufreq_driver sfi_cpufreq_driver = {
82	.flags		= CPUFREQ_CONST_LOOPS,
83	.verify		= cpufreq_generic_frequency_table_verify,
84	.target_index	= sfi_cpufreq_target,
85	.init		= sfi_cpufreq_cpu_init,
86	.name		= "sfi-cpufreq",
87	.attr		= cpufreq_generic_attr,
88};
89
90static int __init sfi_cpufreq_init(void)
91{
92	int ret, i;
93
94	/* parse the freq table from SFI */
95	ret = sfi_table_parse(SFI_SIG_FREQ, NULL, NULL, sfi_parse_freq);
96	if (ret)
97		return ret;
98
99	freq_table = kzalloc(sizeof(*freq_table) *
100			(num_freq_table_entries + 1), GFP_KERNEL);
101	if (!freq_table) {
102		ret = -ENOMEM;
103		goto err_free_array;
104	}
105
106	for (i = 0; i < num_freq_table_entries; i++) {
107		freq_table[i].driver_data = i;
108		freq_table[i].frequency = sfi_cpufreq_array[i].freq_mhz * 1000;
109	}
110	freq_table[i].frequency = CPUFREQ_TABLE_END;
111
112	ret = cpufreq_register_driver(&sfi_cpufreq_driver);
113	if (ret)
114		goto err_free_tbl;
115
116	return ret;
117
118err_free_tbl:
119	kfree(freq_table);
120err_free_array:
121	kfree(sfi_cpufreq_array);
122	return ret;
123}
124late_initcall(sfi_cpufreq_init);
125
126static void __exit sfi_cpufreq_exit(void)
127{
128	cpufreq_unregister_driver(&sfi_cpufreq_driver);
129	kfree(freq_table);
130	kfree(sfi_cpufreq_array);
131}
132module_exit(sfi_cpufreq_exit);
133
134MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>");
135MODULE_DESCRIPTION("SFI Performance-States Driver");
136MODULE_LICENSE("GPL");
137