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/vmalloc.h>
24
25 #include <asm/unaligned.h>
26
27 #include <acpi/cppc_acpi.h>
28
29 /* Minimum struct length needed for the DMI processor entry we want */
30 #define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
31
32 /* Offest in the DMI processor structure for the max frequency */
33 #define DMI_PROCESSOR_MAX_SPEED 0x14
34
35 /*
36 * These structs contain information parsed from per CPU
37 * ACPI _CPC structures.
38 * e.g. For each CPU the highest, lowest supported
39 * performance capabilities, desired performance level
40 * requested etc.
41 */
42 static struct cppc_cpudata **all_cpu_data;
43
44 /* Capture the max KHz from DMI */
45 static u64 cppc_dmi_max_khz;
46
47 /* Callback function used to retrieve the max frequency from DMI */
cppc_find_dmi_mhz(const struct dmi_header * dm,void * private)48 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
49 {
50 const u8 *dmi_data = (const u8 *)dm;
51 u16 *mhz = (u16 *)private;
52
53 if (dm->type == DMI_ENTRY_PROCESSOR &&
54 dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
55 u16 val = (u16)get_unaligned((const u16 *)
56 (dmi_data + DMI_PROCESSOR_MAX_SPEED));
57 *mhz = val > *mhz ? val : *mhz;
58 }
59 }
60
61 /* Look up the max frequency in DMI */
cppc_get_dmi_max_khz(void)62 static u64 cppc_get_dmi_max_khz(void)
63 {
64 u16 mhz = 0;
65
66 dmi_walk(cppc_find_dmi_mhz, &mhz);
67
68 /*
69 * Real stupid fallback value, just in case there is no
70 * actual value set.
71 */
72 mhz = mhz ? mhz : 1;
73
74 return (1000 * mhz);
75 }
76
cppc_cpufreq_set_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)77 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
78 unsigned int target_freq,
79 unsigned int relation)
80 {
81 struct cppc_cpudata *cpu;
82 struct cpufreq_freqs freqs;
83 u32 desired_perf;
84 int ret = 0;
85
86 cpu = all_cpu_data[policy->cpu];
87
88 desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
89 /* Return if it is exactly the same perf */
90 if (desired_perf == cpu->perf_ctrls.desired_perf)
91 return ret;
92
93 cpu->perf_ctrls.desired_perf = desired_perf;
94 freqs.old = policy->cur;
95 freqs.new = target_freq;
96
97 cpufreq_freq_transition_begin(policy, &freqs);
98 ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
99 cpufreq_freq_transition_end(policy, &freqs, ret != 0);
100
101 if (ret)
102 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
103 cpu->cpu, ret);
104
105 return ret;
106 }
107
cppc_verify_policy(struct cpufreq_policy * policy)108 static int cppc_verify_policy(struct cpufreq_policy *policy)
109 {
110 cpufreq_verify_within_cpu_limits(policy);
111 return 0;
112 }
113
cppc_cpufreq_stop_cpu(struct cpufreq_policy * policy)114 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
115 {
116 int cpu_num = policy->cpu;
117 struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
118 int ret;
119
120 cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
121
122 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
123 if (ret)
124 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
125 cpu->perf_caps.lowest_perf, cpu_num, ret);
126 }
127
cppc_cpufreq_cpu_init(struct cpufreq_policy * policy)128 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
129 {
130 struct cppc_cpudata *cpu;
131 unsigned int cpu_num = policy->cpu;
132 int ret = 0;
133
134 cpu = all_cpu_data[policy->cpu];
135
136 cpu->cpu = cpu_num;
137 ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
138
139 if (ret) {
140 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
141 cpu_num, ret);
142 return ret;
143 }
144
145 cppc_dmi_max_khz = cppc_get_dmi_max_khz();
146
147 policy->min = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz / cpu->perf_caps.highest_perf;
148 policy->max = cppc_dmi_max_khz;
149 policy->cpuinfo.min_freq = policy->min;
150 policy->cpuinfo.max_freq = policy->max;
151 policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
152 policy->shared_type = cpu->shared_type;
153
154 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
155 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
156 else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
157 /* Support only SW_ANY for now. */
158 pr_debug("Unsupported CPU co-ord type\n");
159 return -EFAULT;
160 }
161
162 cpumask_set_cpu(policy->cpu, policy->cpus);
163 cpu->cur_policy = policy;
164
165 /* Set policy->cur to max now. The governors will adjust later. */
166 policy->cur = cppc_dmi_max_khz;
167 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
168
169 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
170 if (ret)
171 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
172 cpu->perf_caps.highest_perf, cpu_num, ret);
173
174 return ret;
175 }
176
177 static struct cpufreq_driver cppc_cpufreq_driver = {
178 .flags = CPUFREQ_CONST_LOOPS,
179 .verify = cppc_verify_policy,
180 .target = cppc_cpufreq_set_target,
181 .init = cppc_cpufreq_cpu_init,
182 .stop_cpu = cppc_cpufreq_stop_cpu,
183 .name = "cppc_cpufreq",
184 };
185
cppc_cpufreq_init(void)186 static int __init cppc_cpufreq_init(void)
187 {
188 int i, ret = 0;
189 struct cppc_cpudata *cpu;
190
191 if (acpi_disabled)
192 return -ENODEV;
193
194 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
195 if (!all_cpu_data)
196 return -ENOMEM;
197
198 for_each_possible_cpu(i) {
199 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
200 if (!all_cpu_data[i])
201 goto out;
202
203 cpu = all_cpu_data[i];
204 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
205 goto out;
206 }
207
208 ret = acpi_get_psd_map(all_cpu_data);
209 if (ret) {
210 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
211 goto out;
212 }
213
214 ret = cpufreq_register_driver(&cppc_cpufreq_driver);
215 if (ret)
216 goto out;
217
218 return ret;
219
220 out:
221 for_each_possible_cpu(i)
222 kfree(all_cpu_data[i]);
223
224 kfree(all_cpu_data);
225 return -ENODEV;
226 }
227
cppc_cpufreq_exit(void)228 static void __exit cppc_cpufreq_exit(void)
229 {
230 struct cppc_cpudata *cpu;
231 int i;
232
233 cpufreq_unregister_driver(&cppc_cpufreq_driver);
234
235 for_each_possible_cpu(i) {
236 cpu = all_cpu_data[i];
237 free_cpumask_var(cpu->shared_cpu_map);
238 kfree(cpu);
239 }
240
241 kfree(all_cpu_data);
242 }
243
244 module_exit(cppc_cpufreq_exit);
245 MODULE_AUTHOR("Ashwin Chaugule");
246 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
247 MODULE_LICENSE("GPL");
248
249 late_initcall(cppc_cpufreq_init);
250