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         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
 108 static int cppc_verify_policy(struct cpufreq_policy *policy)
 109 {
 110         cpufreq_verify_within_cpu_limits(policy);
 111         return 0;
 112 }
 113
 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
 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         /*
 148          * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
 149          * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
 150          */
 151         policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
 152                 cpu->perf_caps.highest_perf;
 153         policy->max = cppc_dmi_max_khz;
 154
 155         /*
 156          * Set cpuinfo.min_freq to Lowest to make the full range of performance
 157          * available if userspace wants to use any perf between lowest & lowest
 158          * nonlinear perf
 159          */
 160         policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
 161                 cpu->perf_caps.highest_perf;
 162         policy->cpuinfo.max_freq = cppc_dmi_max_khz;
 163
 164         policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
 165         policy->shared_type = cpu->shared_type;
 166
 167         if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
 168                 cpumask_copy(policy->cpus, cpu->shared_cpu_map);
 169         else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
 170                 /* Support only SW_ANY for now. */
 171                 pr_debug("Unsupported CPU co-ord type\n");
 172                 return -EFAULT;
 173         }
 174
 175         cpu->cur_policy = policy;
 176
 177         /* Set policy->cur to max now. The governors will adjust later. */
 178         policy->cur = cppc_dmi_max_khz;
 179         cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
 180
 181         ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
 182         if (ret)
 183                 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
 184                                 cpu->perf_caps.highest_perf, cpu_num, ret);
 185
 186         return ret;
 187 }
 188
 189 static struct cpufreq_driver cppc_cpufreq_driver = {
 190         .flags = CPUFREQ_CONST_LOOPS,
 191         .verify = cppc_verify_policy,
 192         .target = cppc_cpufreq_set_target,
 193         .init = cppc_cpufreq_cpu_init,
 194         .stop_cpu = cppc_cpufreq_stop_cpu,
 195         .name = "cppc_cpufreq",
 196 };
 197
 198 static int __init cppc_cpufreq_init(void)
 199 {
 200         int i, ret = 0;
 201         struct cppc_cpudata *cpu;
 202
 203         if (acpi_disabled)
 204                 return -ENODEV;
 205
 206         all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
 207         if (!all_cpu_data)
 208                 return -ENOMEM;
 209
 210         for_each_possible_cpu(i) {
 211                 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
 212                 if (!all_cpu_data[i])
 213                         goto out;
 214
 215                 cpu = all_cpu_data[i];
 216                 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
 217                         goto out;
 218         }
 219
 220         ret = acpi_get_psd_map(all_cpu_data);
 221         if (ret) {
 222                 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
 223                 goto out;
 224         }
 225
 226         ret = cpufreq_register_driver(&cppc_cpufreq_driver);
 227         if (ret)
 228                 goto out;
 229
 230         return ret;
 231
 232 out:
 233         for_each_possible_cpu(i)
 234                 kfree(all_cpu_data[i]);
 235
 236         kfree(all_cpu_data);
 237         return -ENODEV;
 238 }
 239
 240 static void __exit cppc_cpufreq_exit(void)
 241 {
 242         struct cppc_cpudata *cpu;
 243         int i;
 244
 245         cpufreq_unregister_driver(&cppc_cpufreq_driver);
 246
 247         for_each_possible_cpu(i) {
 248                 cpu = all_cpu_data[i];
 249                 free_cpumask_var(cpu->shared_cpu_map);
 250                 kfree(cpu);
 251         }
 252
 253         kfree(all_cpu_data);
 254 }
 255
 256 module_exit(cppc_cpufreq_exit);
 257 MODULE_AUTHOR("Ashwin Chaugule");
 258 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
 259 MODULE_LICENSE("GPL");
 260
 261 late_initcall(cppc_cpufreq_init);
 262
 263 static const struct acpi_device_id cppc_acpi_ids[] = {
 264         {ACPI_PROCESSOR_DEVICE_HID, },
 265         {}
 266 };
 267
 268 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);