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); 269