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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 | 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 = 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 | ||
57 | static 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 | ||
73 | static 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 | ||
81 | static 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 | ||
90 | static 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 | ||
118 | err_free_tbl: | |
119 | kfree(freq_table); | |
120 | err_free_array: | |
121 | kfree(sfi_cpufreq_array); | |
122 | return ret; | |
123 | } | |
124 | late_initcall(sfi_cpufreq_init); | |
125 | ||
126 | static void __exit sfi_cpufreq_exit(void) | |
127 | { | |
128 | cpufreq_unregister_driver(&sfi_cpufreq_driver); | |
129 | kfree(freq_table); | |
130 | kfree(sfi_cpufreq_array); | |
131 | } | |
132 | module_exit(sfi_cpufreq_exit); | |
133 | ||
134 | MODULE_AUTHOR("Vishwesh M Rudramuni <vishwesh.m.rudramuni@intel.com>"); | |
135 | MODULE_DESCRIPTION("SFI Performance-States Driver"); | |
136 | MODULE_LICENSE("GPL"); |