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 int ret = 0; 84 85 cpu = all_cpu_data[policy->cpu]; 86 87 cpu->perf_ctrls.desired_perf = (u64)target_freq * policy->max / cppc_dmi_max_khz; 88 freqs.old = policy->cur; 89 freqs.new = target_freq; 90 91 cpufreq_freq_transition_begin(policy, &freqs); 92 ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls); 93 cpufreq_freq_transition_end(policy, &freqs, ret != 0); 94 95 if (ret) 96 pr_debug("Failed to set target on CPU:%d. ret:%d\n", 97 cpu->cpu, ret); 98 99 return ret; 100 } 101 102 static int cppc_verify_policy(struct cpufreq_policy *policy) 103 { 104 cpufreq_verify_within_cpu_limits(policy); 105 return 0; 106 } 107 108 static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy) 109 { 110 int cpu_num = policy->cpu; 111 struct cppc_cpudata *cpu = all_cpu_data[cpu_num]; 112 int ret; 113 114 cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf; 115 116 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls); 117 if (ret) 118 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n", 119 cpu->perf_caps.lowest_perf, cpu_num, ret); 120 } 121 122 static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy) 123 { 124 struct cppc_cpudata *cpu; 125 unsigned int cpu_num = policy->cpu; 126 int ret = 0; 127 128 cpu = all_cpu_data[policy->cpu]; 129 130 cpu->cpu = cpu_num; 131 ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps); 132 133 if (ret) { 134 pr_debug("Err reading CPU%d perf capabilities. ret:%d\n", 135 cpu_num, ret); 136 return ret; 137 } 138 139 cppc_dmi_max_khz = cppc_get_dmi_max_khz(); 140 141 policy->min = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz / cpu->perf_caps.highest_perf; 142 policy->max = cppc_dmi_max_khz; 143 policy->cpuinfo.min_freq = policy->min; 144 policy->cpuinfo.max_freq = policy->max; 145 policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num); 146 policy->shared_type = cpu->shared_type; 147 148 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) 149 cpumask_copy(policy->cpus, cpu->shared_cpu_map); 150 else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) { 151 /* Support only SW_ANY for now. */ 152 pr_debug("Unsupported CPU co-ord type\n"); 153 return -EFAULT; 154 } 155 156 cpumask_set_cpu(policy->cpu, policy->cpus); 157 cpu->cur_policy = policy; 158 159 /* Set policy->cur to max now. The governors will adjust later. */ 160 policy->cur = cppc_dmi_max_khz; 161 cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf; 162 163 ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls); 164 if (ret) 165 pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n", 166 cpu->perf_caps.highest_perf, cpu_num, ret); 167 168 return ret; 169 } 170 171 static struct cpufreq_driver cppc_cpufreq_driver = { 172 .flags = CPUFREQ_CONST_LOOPS, 173 .verify = cppc_verify_policy, 174 .target = cppc_cpufreq_set_target, 175 .init = cppc_cpufreq_cpu_init, 176 .stop_cpu = cppc_cpufreq_stop_cpu, 177 .name = "cppc_cpufreq", 178 }; 179 180 static int __init cppc_cpufreq_init(void) 181 { 182 int i, ret = 0; 183 struct cppc_cpudata *cpu; 184 185 if (acpi_disabled) 186 return -ENODEV; 187 188 all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL); 189 if (!all_cpu_data) 190 return -ENOMEM; 191 192 for_each_possible_cpu(i) { 193 all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL); 194 if (!all_cpu_data[i]) 195 goto out; 196 197 cpu = all_cpu_data[i]; 198 if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL)) 199 goto out; 200 } 201 202 ret = acpi_get_psd_map(all_cpu_data); 203 if (ret) { 204 pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n"); 205 goto out; 206 } 207 208 ret = cpufreq_register_driver(&cppc_cpufreq_driver); 209 if (ret) 210 goto out; 211 212 return ret; 213 214 out: 215 for_each_possible_cpu(i) 216 kfree(all_cpu_data[i]); 217 218 kfree(all_cpu_data); 219 return -ENODEV; 220 } 221 222 static void __exit cppc_cpufreq_exit(void) 223 { 224 struct cppc_cpudata *cpu; 225 int i; 226 227 cpufreq_unregister_driver(&cppc_cpufreq_driver); 228 229 for_each_possible_cpu(i) { 230 cpu = all_cpu_data[i]; 231 free_cpumask_var(cpu->shared_cpu_map); 232 kfree(cpu); 233 } 234 235 kfree(all_cpu_data); 236 } 237 238 module_exit(cppc_cpufreq_exit); 239 MODULE_AUTHOR("Ashwin Chaugule"); 240 MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec"); 241 MODULE_LICENSE("GPL"); 242 243 late_initcall(cppc_cpufreq_init); 244