drivers/cpufreq/cppc_cpufreq.c

   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 */
  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 */
  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
  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         int ret = 0;
  84
  85         cpu = all_cpu_data[policy->cpu];
  86
  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;
  90
  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);
  94
  95         if (ret)
  96                 pr_debug("Failed to set target on CPU:%d. ret:%d\n",
  97                                 cpu->cpu, ret);
  98
  99         return ret;
 100 }
 101
 102 static int cppc_verify_policy(struct cpufreq_policy *policy)
 103 {
 104         cpufreq_verify_within_cpu_limits(policy);
 105         return 0;
 106 }
 107
 108 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
 109 {
 110         int cpu_num = policy->cpu;
 111         struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
 112         int ret;
 113
 114         cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
 115
 116         ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
 117         if (ret)
 118                 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 119                                 cpu->perf_caps.lowest_perf, cpu_num, ret);
 120 }
 121
 122 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
 123 {
 124         struct cppc_cpudata *cpu;
 125         unsigned int cpu_num = policy->cpu;
 126         int ret = 0;
 127
 128         cpu = all_cpu_data[policy->cpu];
 129
 130         cpu->cpu = cpu_num;
 131         ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
 132
 133         if (ret) {
 134                 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
 135                                 cpu_num, ret);
 136                 return ret;
 137         }
 138
 139         cppc_dmi_max_khz = cppc_get_dmi_max_khz();
 140
 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;
 147
 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");
 153                 return -EFAULT;
 154         }
 155
 156         cpumask_set_cpu(policy->cpu, policy->cpus);
 157         cpu->cur_policy = policy;
 158
 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;
 162
 163         ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
 164         if (ret)
 165                 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 166                                 cpu->perf_caps.highest_perf, cpu_num, ret);
 167
 168         return ret;
 169 }
 170
 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",
 178 };
 179
 180 static int __init cppc_cpufreq_init(void)
 181 {
 182         int i, ret = 0;
 183         struct cppc_cpudata *cpu;
 184
 185         if (acpi_disabled)
 186                 return -ENODEV;
 187
 188         all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
 189         if (!all_cpu_data)
 190                 return -ENOMEM;
 191
 192         for_each_possible_cpu(i) {
 193                 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
 194                 if (!all_cpu_data[i])
 195                         goto out;
 196
 197                 cpu = all_cpu_data[i];
 198                 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
 199                         goto out;
 200         }
 201
 202         ret = acpi_get_psd_map(all_cpu_data);
 203         if (ret) {
 204                 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
 205                 goto out;
 206         }
 207
 208         ret = cpufreq_register_driver(&cppc_cpufreq_driver);
 209         if (ret)
 210                 goto out;
 211
 212         return ret;
 213
 214 out:
 215         for_each_possible_cpu(i)
 216                 kfree(all_cpu_data[i]);
 217
 218         kfree(all_cpu_data);
 219         return -ENODEV;
 220 }
 221
 222 static void __exit cppc_cpufreq_exit(void)
 223 {
 224         struct cppc_cpudata *cpu;
 225         int i;
 226
 227         cpufreq_unregister_driver(&cppc_cpufreq_driver);
 228
 229         for_each_possible_cpu(i) {
 230                 cpu = all_cpu_data[i];
 231                 free_cpumask_var(cpu->shared_cpu_map);
 232                 kfree(cpu);
 233         }
 234
 235         kfree(all_cpu_data);
 236 }
 237
 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");
 242
 243 late_initcall(cppc_cpufreq_init);