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/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  */
  43 static struct cppc_cpudata **all_cpu_data;
  44
  45 /* Capture the max KHz from DMI */
  46 static u64 cppc_dmi_max_khz;
  47
  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)
  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 */
  63 static 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
  78 static 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
 109 static int cppc_verify_policy(struct cpufreq_policy *policy)
 110 {
 111         cpufreq_verify_within_cpu_limits(policy);
 112         return 0;
 113 }
 114
 115 static 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
 129 static 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->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
 166         policy->transition_delay_us = cppc_get_transition_latency(cpu_num) /
 167                 NSEC_PER_USEC;
 168         policy->shared_type = cpu->shared_type;
 169
 170         if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
 171                 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
 172         else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
 173                 /* Support only SW_ANY for now. */
 174                 pr_debug("Unsupported CPU co-ord type\n");
 175                 return -EFAULT;
 176         }
 177
 178         cpu->cur_policy = policy;
 179
 180         /* Set policy->cur to max now. The governors will adjust later. */
 181         policy->cur = cppc_dmi_max_khz;
 182         cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
 183
 184         ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
 185         if (ret)
 186                 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 187                                 cpu->perf_caps.highest_perf, cpu_num, ret);
 188
 189         return ret;
 190 }
 191
 192 static struct cpufreq_driver cppc_cpufreq_driver = {
 193         .flags = CPUFREQ_CONST_LOOPS,
 194         .verify = cppc_verify_policy,
 195         .target = cppc_cpufreq_set_target,
 196         .init = cppc_cpufreq_cpu_init,
 197         .stop_cpu = cppc_cpufreq_stop_cpu,
 198         .name = "cppc_cpufreq",
 199 };
 200
 201 static int __init cppc_cpufreq_init(void)
 202 {
 203         int i, ret = 0;
 204         struct cppc_cpudata *cpu;
 205
 206         if (acpi_disabled)
 207                 return -ENODEV;
 208
 209         all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
 210         if (!all_cpu_data)
 211                 return -ENOMEM;
 212
 213         for_each_possible_cpu(i) {
 214                 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
 215                 if (!all_cpu_data[i])
 216                         goto out;
 217
 218                 cpu = all_cpu_data[i];
 219                 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
 220                         goto out;
 221         }
 222
 223         ret = acpi_get_psd_map(all_cpu_data);
 224         if (ret) {
 225                 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
 226                 goto out;
 227         }
 228
 229         ret = cpufreq_register_driver(&cppc_cpufreq_driver);
 230         if (ret)
 231                 goto out;
 232
 233         return ret;
 234
 235 out:
 236         for_each_possible_cpu(i)
 237                 kfree(all_cpu_data[i]);
 238
 239         kfree(all_cpu_data);
 240         return -ENODEV;
 241 }
 242
 243 static void __exit cppc_cpufreq_exit(void)
 244 {
 245         struct cppc_cpudata *cpu;
 246         int i;
 247
 248         cpufreq_unregister_driver(&cppc_cpufreq_driver);
 249
 250         for_each_possible_cpu(i) {
 251                 cpu = all_cpu_data[i];
 252                 free_cpumask_var(cpu->shared_cpu_map);
 253                 kfree(cpu);
 254         }
 255
 256         kfree(all_cpu_data);
 257 }
 258
 259 module_exit(cppc_cpufreq_exit);
 260 MODULE_AUTHOR("Ashwin Chaugule");
 261 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
 262 MODULE_LICENSE("GPL");
 263
 264 late_initcall(cppc_cpufreq_init);
 265
 266 static const struct acpi_device_id cppc_acpi_ids[] = {
 267         {ACPI_PROCESSOR_DEVICE_HID, },
 268         {}
 269 };
 270
 271 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);