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.
6 * (C) Copyright 2014, 2015 Linaro Ltd.
7 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
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
15 #define pr_fmt(fmt) "CPPC Cpufreq:" fmt
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>
25 #include <asm/unaligned.h>
27 #include <acpi/cppc_acpi.h>
29 /* Minimum struct length needed for the DMI processor entry we want */
30 #define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
32 /* Offest in the DMI processor structure for the max frequency */
33 #define DMI_PROCESSOR_MAX_SPEED 0x14
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
42 static struct cppc_cpudata **all_cpu_data;
44 /* Capture the max KHz from DMI */
45 static u64 cppc_dmi_max_khz;
47 /* Callback function used to retrieve the max frequency from DMI */
48 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
50 const u8 *dmi_data = (const u8 *)dm;
51 u16 *mhz = (u16 *)private;
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;
61 /* Look up the max frequency in DMI */
62 static u64 cppc_get_dmi_max_khz(void)
66 dmi_walk(cppc_find_dmi_mhz, &mhz);
69 * Real stupid fallback value, just in case there is no
77 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
78 unsigned int target_freq,
79 unsigned int relation)
81 struct cppc_cpudata *cpu;
82 struct cpufreq_freqs freqs;
85 cpu = all_cpu_data[policy->cpu];
87 cpu->perf_ctrls.desired_perf = (u64)target_freq * policy->max / cppc_dmi_max_khz;
88 freqs.old = policy->cur;
89 freqs.new = target_freq;
91 cpufreq_freq_transition_begin(policy, &freqs);
92 ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
93 cpufreq_freq_transition_end(policy, &freqs, ret != 0);
96 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
102 static int cppc_verify_policy(struct cpufreq_policy *policy)
104 cpufreq_verify_within_cpu_limits(policy);
108 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
110 int cpu_num = policy->cpu;
111 struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
114 cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
116 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
118 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
119 cpu->perf_caps.lowest_perf, cpu_num, ret);
122 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
124 struct cppc_cpudata *cpu;
125 unsigned int cpu_num = policy->cpu;
128 cpu = all_cpu_data[policy->cpu];
131 ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
134 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
139 cppc_dmi_max_khz = cppc_get_dmi_max_khz();
141 policy->min = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz / cpu->perf_caps.highest_perf;
142 policy->max = cppc_dmi_max_khz;
143 policy->cpuinfo.min_freq = policy->min;
144 policy->cpuinfo.max_freq = policy->max;
145 policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
146 policy->shared_type = cpu->shared_type;
148 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
149 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
150 else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
151 /* Support only SW_ANY for now. */
152 pr_debug("Unsupported CPU co-ord type\n");
156 cpumask_set_cpu(policy->cpu, policy->cpus);
157 cpu->cur_policy = policy;
159 /* Set policy->cur to max now. The governors will adjust later. */
160 policy->cur = cppc_dmi_max_khz;
161 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
163 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
165 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
166 cpu->perf_caps.highest_perf, cpu_num, ret);
171 static struct cpufreq_driver cppc_cpufreq_driver = {
172 .flags = CPUFREQ_CONST_LOOPS,
173 .verify = cppc_verify_policy,
174 .target = cppc_cpufreq_set_target,
175 .init = cppc_cpufreq_cpu_init,
176 .stop_cpu = cppc_cpufreq_stop_cpu,
177 .name = "cppc_cpufreq",
180 static int __init cppc_cpufreq_init(void)
183 struct cppc_cpudata *cpu;
188 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
192 for_each_possible_cpu(i) {
193 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
194 if (!all_cpu_data[i])
197 cpu = all_cpu_data[i];
198 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
202 ret = acpi_get_psd_map(all_cpu_data);
204 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
208 ret = cpufreq_register_driver(&cppc_cpufreq_driver);
215 for_each_possible_cpu(i)
216 kfree(all_cpu_data[i]);
222 static void __exit cppc_cpufreq_exit(void)
224 struct cppc_cpudata *cpu;
227 cpufreq_unregister_driver(&cppc_cpufreq_driver);
229 for_each_possible_cpu(i) {
230 cpu = all_cpu_data[i];
231 free_cpumask_var(cpu->shared_cpu_map);
238 module_exit(cppc_cpufreq_exit);
239 MODULE_AUTHOR("Ashwin Chaugule");
240 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
241 MODULE_LICENSE("GPL");
243 late_initcall(cppc_cpufreq_init);