Linux kernel mirror (for testing)
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1/*
2 * CPPC (Collaborative Processor Performance Control) driver for
3 * interfacing with the CPUfreq layer and governors. See
4 * cppc_acpi.c for CPPC specific methods.
5 *
6 * (C) Copyright 2014, 2015 Linaro Ltd.
7 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; version 2
12 * of the License.
13 */
14
15#define pr_fmt(fmt) "CPPC Cpufreq:" fmt
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/delay.h>
20#include <linux/cpu.h>
21#include <linux/cpufreq.h>
22#include <linux/dmi.h>
23#include <linux/time.h>
24#include <linux/vmalloc.h>
25
26#include <asm/unaligned.h>
27
28#include <acpi/cppc_acpi.h>
29
30/* Minimum struct length needed for the DMI processor entry we want */
31#define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
32
33/* Offest in the DMI processor structure for the max frequency */
34#define DMI_PROCESSOR_MAX_SPEED 0x14
35
36/*
37 * These structs contain information parsed from per CPU
38 * ACPI _CPC structures.
39 * e.g. For each CPU the highest, lowest supported
40 * performance capabilities, desired performance level
41 * requested etc.
42 */
43static struct cppc_cpudata **all_cpu_data;
44
45/* Capture the max KHz from DMI */
46static u64 cppc_dmi_max_khz;
47
48/* Callback function used to retrieve the max frequency from DMI */
49static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
50{
51 const u8 *dmi_data = (const u8 *)dm;
52 u16 *mhz = (u16 *)private;
53
54 if (dm->type == DMI_ENTRY_PROCESSOR &&
55 dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
56 u16 val = (u16)get_unaligned((const u16 *)
57 (dmi_data + DMI_PROCESSOR_MAX_SPEED));
58 *mhz = val > *mhz ? val : *mhz;
59 }
60}
61
62/* Look up the max frequency in DMI */
63static u64 cppc_get_dmi_max_khz(void)
64{
65 u16 mhz = 0;
66
67 dmi_walk(cppc_find_dmi_mhz, &mhz);
68
69 /*
70 * Real stupid fallback value, just in case there is no
71 * actual value set.
72 */
73 mhz = mhz ? mhz : 1;
74
75 return (1000 * mhz);
76}
77
78static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
79 unsigned int target_freq,
80 unsigned int relation)
81{
82 struct cppc_cpudata *cpu;
83 struct cpufreq_freqs freqs;
84 u32 desired_perf;
85 int ret = 0;
86
87 cpu = all_cpu_data[policy->cpu];
88
89 desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
90 /* Return if it is exactly the same perf */
91 if (desired_perf == cpu->perf_ctrls.desired_perf)
92 return ret;
93
94 cpu->perf_ctrls.desired_perf = desired_perf;
95 freqs.old = policy->cur;
96 freqs.new = target_freq;
97
98 cpufreq_freq_transition_begin(policy, &freqs);
99 ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
100 cpufreq_freq_transition_end(policy, &freqs, ret != 0);
101
102 if (ret)
103 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
104 cpu->cpu, ret);
105
106 return ret;
107}
108
109static int cppc_verify_policy(struct cpufreq_policy *policy)
110{
111 cpufreq_verify_within_cpu_limits(policy);
112 return 0;
113}
114
115static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
116{
117 int cpu_num = policy->cpu;
118 struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
119 int ret;
120
121 cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
122
123 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
124 if (ret)
125 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
126 cpu->perf_caps.lowest_perf, cpu_num, ret);
127}
128
129static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
130{
131 struct cppc_cpudata *cpu;
132 unsigned int cpu_num = policy->cpu;
133 int ret = 0;
134
135 cpu = all_cpu_data[policy->cpu];
136
137 cpu->cpu = cpu_num;
138 ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
139
140 if (ret) {
141 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
142 cpu_num, ret);
143 return ret;
144 }
145
146 cppc_dmi_max_khz = cppc_get_dmi_max_khz();
147
148 /*
149 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
150 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
151 */
152 policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
153 cpu->perf_caps.highest_perf;
154 policy->max = cppc_dmi_max_khz;
155
156 /*
157 * Set cpuinfo.min_freq to Lowest to make the full range of performance
158 * available if userspace wants to use any perf between lowest & lowest
159 * nonlinear perf
160 */
161 policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
162 cpu->perf_caps.highest_perf;
163 policy->cpuinfo.max_freq = cppc_dmi_max_khz;
164
165 policy->transition_delay_us = cppc_get_transition_latency(cpu_num) /
166 NSEC_PER_USEC;
167 policy->shared_type = cpu->shared_type;
168
169 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
170 int i;
171
172 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
173
174 for_each_cpu(i, policy->cpus) {
175 if (unlikely(i == policy->cpu))
176 continue;
177
178 memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
179 sizeof(cpu->perf_caps));
180 }
181 } else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
182 /* Support only SW_ANY for now. */
183 pr_debug("Unsupported CPU co-ord type\n");
184 return -EFAULT;
185 }
186
187 cpu->cur_policy = policy;
188
189 /* Set policy->cur to max now. The governors will adjust later. */
190 policy->cur = cppc_dmi_max_khz;
191 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
192
193 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
194 if (ret)
195 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
196 cpu->perf_caps.highest_perf, cpu_num, ret);
197
198 return ret;
199}
200
201static struct cpufreq_driver cppc_cpufreq_driver = {
202 .flags = CPUFREQ_CONST_LOOPS,
203 .verify = cppc_verify_policy,
204 .target = cppc_cpufreq_set_target,
205 .init = cppc_cpufreq_cpu_init,
206 .stop_cpu = cppc_cpufreq_stop_cpu,
207 .name = "cppc_cpufreq",
208};
209
210static int __init cppc_cpufreq_init(void)
211{
212 int i, ret = 0;
213 struct cppc_cpudata *cpu;
214
215 if (acpi_disabled)
216 return -ENODEV;
217
218 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
219 if (!all_cpu_data)
220 return -ENOMEM;
221
222 for_each_possible_cpu(i) {
223 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
224 if (!all_cpu_data[i])
225 goto out;
226
227 cpu = all_cpu_data[i];
228 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
229 goto out;
230 }
231
232 ret = acpi_get_psd_map(all_cpu_data);
233 if (ret) {
234 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
235 goto out;
236 }
237
238 ret = cpufreq_register_driver(&cppc_cpufreq_driver);
239 if (ret)
240 goto out;
241
242 return ret;
243
244out:
245 for_each_possible_cpu(i) {
246 cpu = all_cpu_data[i];
247 if (!cpu)
248 break;
249 free_cpumask_var(cpu->shared_cpu_map);
250 kfree(cpu);
251 }
252
253 kfree(all_cpu_data);
254 return -ENODEV;
255}
256
257static void __exit cppc_cpufreq_exit(void)
258{
259 struct cppc_cpudata *cpu;
260 int i;
261
262 cpufreq_unregister_driver(&cppc_cpufreq_driver);
263
264 for_each_possible_cpu(i) {
265 cpu = all_cpu_data[i];
266 free_cpumask_var(cpu->shared_cpu_map);
267 kfree(cpu);
268 }
269
270 kfree(all_cpu_data);
271}
272
273module_exit(cppc_cpufreq_exit);
274MODULE_AUTHOR("Ashwin Chaugule");
275MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
276MODULE_LICENSE("GPL");
277
278late_initcall(cppc_cpufreq_init);
279
280static const struct acpi_device_id cppc_acpi_ids[] = {
281 {ACPI_PROCESSOR_DEVICE_HID, },
282 {}
283};
284
285MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);