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/time.h>
24 #include <linux/vmalloc.h>
26 #include <asm/unaligned.h>
28 #include <acpi/cppc_acpi.h>
30 /* Minimum struct length needed for the DMI processor entry we want */
31 #define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
33 /* Offest in the DMI processor structure for the max frequency */
34 #define DMI_PROCESSOR_MAX_SPEED 0x14
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
43 static struct cppc_cpudata **all_cpu_data;
45 /* Capture the max KHz from DMI */
46 static u64 cppc_dmi_max_khz;
48 /* Callback function used to retrieve the max frequency from DMI */
49 static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
51 const u8 *dmi_data = (const u8 *)dm;
52 u16 *mhz = (u16 *)private;
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;
62 /* Look up the max frequency in DMI */
63 static u64 cppc_get_dmi_max_khz(void)
67 dmi_walk(cppc_find_dmi_mhz, &mhz);
70 * Real stupid fallback value, just in case there is no
78 static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
79 unsigned int target_freq,
80 unsigned int relation)
82 struct cppc_cpudata *cpu;
83 struct cpufreq_freqs freqs;
87 cpu = all_cpu_data[policy->cpu];
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)
94 cpu->perf_ctrls.desired_perf = desired_perf;
95 freqs.old = policy->cur;
96 freqs.new = target_freq;
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);
103 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
109 static int cppc_verify_policy(struct cpufreq_policy *policy)
111 cpufreq_verify_within_cpu_limits(policy);
115 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
117 int cpu_num = policy->cpu;
118 struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
121 cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
123 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
125 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
126 cpu->perf_caps.lowest_perf, cpu_num, ret);
130 * The PCC subspace describes the rate at which platform can accept commands
131 * on the shared PCC channel (including READs which do not count towards freq
132 * trasition requests), so ideally we need to use the PCC values as a fallback
133 * if we don't have a platform specific transition_delay_us
136 #include <asm/cputype.h>
138 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
140 unsigned long implementor = read_cpuid_implementor();
141 unsigned long part_num = read_cpuid_part_number();
142 unsigned int delay_us = 0;
144 switch (implementor) {
145 case ARM_CPU_IMP_QCOM:
147 case QCOM_CPU_PART_FALKOR_V1:
148 case QCOM_CPU_PART_FALKOR:
152 delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
157 delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
166 static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
168 return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
172 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
174 struct cppc_cpudata *cpu;
175 unsigned int cpu_num = policy->cpu;
178 cpu = all_cpu_data[policy->cpu];
181 ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
184 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
189 cppc_dmi_max_khz = cppc_get_dmi_max_khz();
192 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
193 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
195 policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
196 cpu->perf_caps.highest_perf;
197 policy->max = cppc_dmi_max_khz;
200 * Set cpuinfo.min_freq to Lowest to make the full range of performance
201 * available if userspace wants to use any perf between lowest & lowest
204 policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
205 cpu->perf_caps.highest_perf;
206 policy->cpuinfo.max_freq = cppc_dmi_max_khz;
208 policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
209 policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
210 policy->shared_type = cpu->shared_type;
212 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
215 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
217 for_each_cpu(i, policy->cpus) {
218 if (unlikely(i == policy->cpu))
221 memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
222 sizeof(cpu->perf_caps));
224 } else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
225 /* Support only SW_ANY for now. */
226 pr_debug("Unsupported CPU co-ord type\n");
230 cpu->cur_policy = policy;
232 /* Set policy->cur to max now. The governors will adjust later. */
233 policy->cur = cppc_dmi_max_khz;
234 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
236 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
238 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
239 cpu->perf_caps.highest_perf, cpu_num, ret);
244 static struct cpufreq_driver cppc_cpufreq_driver = {
245 .flags = CPUFREQ_CONST_LOOPS,
246 .verify = cppc_verify_policy,
247 .target = cppc_cpufreq_set_target,
248 .init = cppc_cpufreq_cpu_init,
249 .stop_cpu = cppc_cpufreq_stop_cpu,
250 .name = "cppc_cpufreq",
253 static int __init cppc_cpufreq_init(void)
256 struct cppc_cpudata *cpu;
261 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
265 for_each_possible_cpu(i) {
266 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
267 if (!all_cpu_data[i])
270 cpu = all_cpu_data[i];
271 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
275 ret = acpi_get_psd_map(all_cpu_data);
277 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
281 ret = cpufreq_register_driver(&cppc_cpufreq_driver);
288 for_each_possible_cpu(i) {
289 cpu = all_cpu_data[i];
292 free_cpumask_var(cpu->shared_cpu_map);
300 static void __exit cppc_cpufreq_exit(void)
302 struct cppc_cpudata *cpu;
305 cpufreq_unregister_driver(&cppc_cpufreq_driver);
307 for_each_possible_cpu(i) {
308 cpu = all_cpu_data[i];
309 free_cpumask_var(cpu->shared_cpu_map);
316 module_exit(cppc_cpufreq_exit);
317 MODULE_AUTHOR("Ashwin Chaugule");
318 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
319 MODULE_LICENSE("GPL");
321 late_initcall(cppc_cpufreq_init);
323 static const struct acpi_device_id cppc_acpi_ids[] = {
324 {ACPI_PROCESSOR_DEVICE_HID, },
328 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);