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 cpu = all_cpu_data[i]; 238 if (!cpu) 239 break; 240 free_cpumask_var(cpu->shared_cpu_map); 241 kfree(cpu); 242 } 243 244 kfree(all_cpu_data); 245 return -ENODEV; 246 } 247 248 static void __exit cppc_cpufreq_exit(void) 249 { 250 struct cppc_cpudata *cpu; 251 int i; 252 253 cpufreq_unregister_driver(&cppc_cpufreq_driver); 254 255 for_each_possible_cpu(i) { 256 cpu = all_cpu_data[i]; 257 free_cpumask_var(cpu->shared_cpu_map); 258 kfree(cpu); 259 } 260 261 kfree(all_cpu_data); 262 } 263 264 module_exit(cppc_cpufreq_exit); 265 MODULE_AUTHOR("Ashwin Chaugule"); 266 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec"); 267 MODULE_LICENSE("GPL"); 268 269 late_initcall(cppc_cpufreq_init); 270 271 static const struct acpi_device_id cppc_acpi_ids[] = { 272 {ACPI_PROCESSOR_DEVICE_HID, }, 273 {} 274 }; 275 276 MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids); 277