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->transition_delay_us = cppc_get_transition_latency(cpu_num) / 166 NSEC_PER_USEC; 167 policy->shared_type = cpu->shared_type; 168 169 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) { 170 int i; 171 172 cpumask_copy(policy->cpus, cpu->shared_cpu_map); 173 174 for_each_cpu(i, policy->cpus) { 175 if (unlikely(i == policy->cpu)) 176 continue; 177 178 memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps, 179 sizeof(cpu->perf_caps)); 180 } 181 } else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) { 182 /* Support only SW_ANY for now. */ 183 pr_debug("Unsupported CPU co-ord type\n"); 184 return -EFAULT; 185 } 186 187 cpu->cur_policy = policy; 188 189 /* Set policy->cur to max now. The governors will adjust later. */ 190 policy->cur = cppc_dmi_max_khz; 191 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf; 192 193 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls); 194 if (ret) 195 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n", 196 cpu->perf_caps.highest_perf, cpu_num, ret); 197 198 return ret; 199 } 200 201 static struct cpufreq_driver cppc_cpufreq_driver = { 202 .flags = CPUFREQ_CONST_LOOPS, 203 .verify = cppc_verify_policy, 204 .target = cppc_cpufreq_set_target, 205 .init = cppc_cpufreq_cpu_init, 206 .stop_cpu = cppc_cpufreq_stop_cpu, 207 .name = "cppc_cpufreq", 208 }; 209 210 static int __init cppc_cpufreq_init(void) 211 { 212 int i, ret = 0; 213 struct cppc_cpudata *cpu; 214 215 if (acpi_disabled) 216 return -ENODEV; 217 218 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL); 219 if (!all_cpu_data) 220 return -ENOMEM; 221 222 for_each_possible_cpu(i) { 223 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL); 224 if (!all_cpu_data[i]) 225 goto out; 226 227 cpu = all_cpu_data[i]; 228 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL)) 229 goto out; 230 } 231 232 ret = acpi_get_psd_map(all_cpu_data); 233 if (ret) { 234 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n"); 235 goto out; 236 } 237 238 ret = cpufreq_register_driver(&cppc_cpufreq_driver); 239 if (ret) 240 goto out; 241 242 return ret; 243 244 out: 245 for_each_possible_cpu(i) { 246 cpu = all_cpu_data[i]; 247 if (!cpu) 248 break; 249 free_cpumask_var(cpu->shared_cpu_map); 250 kfree(cpu); 251 } 252 253 kfree(all_cpu_data); 254 return -ENODEV; 255 } 256 257 static void __exit cppc_cpufreq_exit(void) 258 { 259 struct cppc_cpudata *cpu; 260 int i; 261 262 cpufreq_unregister_driver(&cppc_cpufreq_driver); 263 264 for_each_possible_cpu(i) { 265 cpu = all_cpu_data[i]; 266 free_cpumask_var(cpu->shared_cpu_map); 267 kfree(cpu); 268 } 269 270 kfree(all_cpu_data); 271 } 272 273 module_exit(cppc_cpufreq_exit); 274 MODULE_AUTHOR("Ashwin Chaugule"); 275 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec"); 276 MODULE_LICENSE("GPL"); 277 278 late_initcall(cppc_cpufreq_init); 279 280 static const struct acpi_device_id cppc_acpi_ids[] = { 281 {ACPI_PROCESSOR_DEVICE_HID, }, 282 {} 283 }; 284 285 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids); 286