arch/arm64/kernel/topology.c

   1 /*
   2  * arch/arm64/kernel/topology.c
   3  *
   4  * Copyright (C) 2011,2013,2014 Linaro Limited.
   5  *
   6  * Based on the arm32 version written by Vincent Guittot in turn based on
   7  * arch/sh/kernel/topology.c
   8  *
   9  * This file is subject to the terms and conditions of the GNU General Public
  10  * License.  See the file "COPYING" in the main directory of this archive
  11  * for more details.
  12  */
  13
  14 #include <linux/acpi.h>
  15 #include <linux/arch_topology.h>
  16 #include <linux/cacheinfo.h>
  17 #include <linux/cpufreq.h>
  18 #include <linux/init.h>
  19 #include <linux/percpu.h>
  20
  21 #include <asm/cpu.h>
  22 #include <asm/cputype.h>
  23 #include <asm/topology.h>
  24
  25 #ifdef CONFIG_ACPI
  26 static bool __init acpi_cpu_is_threaded(int cpu)
  27 {
  28         int is_threaded = acpi_pptt_cpu_is_thread(cpu);
  29
  30         /*
  31          * if the PPTT doesn't have thread information, assume a homogeneous
  32          * machine and return the current CPU's thread state.
  33          */
  34         if (is_threaded < 0)
  35                 is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
  36
  37         return !!is_threaded;
  38 }
  39
  40 /*
  41  * Propagate the topology information of the processor_topology_node tree to the
  42  * cpu_topology array.
  43  */
  44 int __init parse_acpi_topology(void)
  45 {
  46         int cpu, topology_id;
  47
  48         if (acpi_disabled)
  49                 return 0;
  50
  51         for_each_possible_cpu(cpu) {
  52                 topology_id = find_acpi_cpu_topology(cpu, 0);
  53                 if (topology_id < 0)
  54                         return topology_id;
  55
  56                 if (acpi_cpu_is_threaded(cpu)) {
  57                         cpu_topology[cpu].thread_id = topology_id;
  58                         topology_id = find_acpi_cpu_topology(cpu, 1);
  59                         cpu_topology[cpu].core_id   = topology_id;
  60                 } else {
  61                         cpu_topology[cpu].thread_id  = -1;
  62                         cpu_topology[cpu].core_id    = topology_id;
  63                 }
  64                 topology_id = find_acpi_cpu_topology_cluster(cpu);
  65                 cpu_topology[cpu].cluster_id = topology_id;
  66                 topology_id = find_acpi_cpu_topology_package(cpu);
  67                 cpu_topology[cpu].package_id = topology_id;
  68         }
  69
  70         return 0;
  71 }
  72 #endif
  73
  74 #ifdef CONFIG_ARM64_AMU_EXTN
  75 #define read_corecnt()  read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0)
  76 #define read_constcnt() read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0)
  77 #else
  78 #define read_corecnt()  (0UL)
  79 #define read_constcnt() (0UL)
  80 #endif
  81
  82 #undef pr_fmt
  83 #define pr_fmt(fmt) "AMU: " fmt
  84
  85 static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, arch_max_freq_scale);
  86 static DEFINE_PER_CPU(u64, arch_const_cycles_prev);
  87 static DEFINE_PER_CPU(u64, arch_core_cycles_prev);
  88 static cpumask_var_t amu_fie_cpus;
  89
  90 void update_freq_counters_refs(void)
  91 {
  92         this_cpu_write(arch_core_cycles_prev, read_corecnt());
  93         this_cpu_write(arch_const_cycles_prev, read_constcnt());
  94 }
  95
  96 static inline bool freq_counters_valid(int cpu)
  97 {
  98         if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask))
  99                 return false;
 100
 101         if (!cpu_has_amu_feat(cpu)) {
 102                 pr_debug("CPU%d: counters are not supported.\n", cpu);
 103                 return false;
 104         }
 105
 106         if (unlikely(!per_cpu(arch_const_cycles_prev, cpu) ||
 107                      !per_cpu(arch_core_cycles_prev, cpu))) {
 108                 pr_debug("CPU%d: cycle counters are not enabled.\n", cpu);
 109                 return false;
 110         }
 111
 112         return true;
 113 }
 114
 115 static int freq_inv_set_max_ratio(int cpu, u64 max_rate, u64 ref_rate)
 116 {
 117         u64 ratio;
 118
 119         if (unlikely(!max_rate || !ref_rate)) {
 120                 pr_debug("CPU%d: invalid maximum or reference frequency.\n",
 121                          cpu);
 122                 return -EINVAL;
 123         }
 124
 125         /*
 126          * Pre-compute the fixed ratio between the frequency of the constant
 127          * reference counter and the maximum frequency of the CPU.
 128          *
 129          *                          ref_rate
 130          * arch_max_freq_scale =   ---------- * SCHED_CAPACITY_SCALE²
 131          *                          max_rate
 132          *
 133          * We use a factor of 2 * SCHED_CAPACITY_SHIFT -> SCHED_CAPACITY_SCALE²
 134          * in order to ensure a good resolution for arch_max_freq_scale for
 135          * very low reference frequencies (down to the KHz range which should
 136          * be unlikely).
 137          */
 138         ratio = ref_rate << (2 * SCHED_CAPACITY_SHIFT);
 139         ratio = div64_u64(ratio, max_rate);
 140         if (!ratio) {
 141                 WARN_ONCE(1, "Reference frequency too low.\n");
 142                 return -EINVAL;
 143         }
 144
 145         per_cpu(arch_max_freq_scale, cpu) = (unsigned long)ratio;
 146
 147         return 0;
 148 }
 149
 150 static void amu_scale_freq_tick(void)
 151 {
 152         u64 prev_core_cnt, prev_const_cnt;
 153         u64 core_cnt, const_cnt, scale;
 154
 155         prev_const_cnt = this_cpu_read(arch_const_cycles_prev);
 156         prev_core_cnt = this_cpu_read(arch_core_cycles_prev);
 157
 158         update_freq_counters_refs();
 159
 160         const_cnt = this_cpu_read(arch_const_cycles_prev);
 161         core_cnt = this_cpu_read(arch_core_cycles_prev);
 162
 163         if (unlikely(core_cnt <= prev_core_cnt ||
 164                      const_cnt <= prev_const_cnt))
 165                 return;
 166
 167         /*
 168          *          /\core    arch_max_freq_scale
 169          * scale =  ------- * --------------------
 170          *          /\const   SCHED_CAPACITY_SCALE
 171          *
 172          * See validate_cpu_freq_invariance_counters() for details on
 173          * arch_max_freq_scale and the use of SCHED_CAPACITY_SHIFT.
 174          */
 175         scale = core_cnt - prev_core_cnt;
 176         scale *= this_cpu_read(arch_max_freq_scale);
 177         scale = div64_u64(scale >> SCHED_CAPACITY_SHIFT,
 178                           const_cnt - prev_const_cnt);
 179
 180         scale = min_t(unsigned long, scale, SCHED_CAPACITY_SCALE);
 181         this_cpu_write(arch_freq_scale, (unsigned long)scale);
 182 }
 183
 184 static struct scale_freq_data amu_sfd = {
 185         .source = SCALE_FREQ_SOURCE_ARCH,
 186         .set_freq_scale = amu_scale_freq_tick,
 187 };
 188
 189 static void amu_fie_setup(const struct cpumask *cpus)
 190 {
 191         int cpu;
 192
 193         /* We are already set since the last insmod of cpufreq driver */
 194         if (unlikely(cpumask_subset(cpus, amu_fie_cpus)))
 195                 return;
 196
 197         for_each_cpu(cpu, cpus) {
 198                 if (!freq_counters_valid(cpu) ||
 199                     freq_inv_set_max_ratio(cpu,
 200                                            cpufreq_get_hw_max_freq(cpu) * 1000ULL,
 201                                            arch_timer_get_rate()))
 202                         return;
 203         }
 204
 205         cpumask_or(amu_fie_cpus, amu_fie_cpus, cpus);
 206
 207         topology_set_scale_freq_source(&amu_sfd, amu_fie_cpus);
 208
 209         pr_debug("CPUs[%*pbl]: counters will be used for FIE.",
 210                  cpumask_pr_args(cpus));
 211 }
 212
 213 static int init_amu_fie_callback(struct notifier_block *nb, unsigned long val,
 214                                  void *data)
 215 {
 216         struct cpufreq_policy *policy = data;
 217
 218         if (val == CPUFREQ_CREATE_POLICY)
 219                 amu_fie_setup(policy->related_cpus);
 220
 221         /*
 222          * We don't need to handle CPUFREQ_REMOVE_POLICY event as the AMU
 223          * counters don't have any dependency on cpufreq driver once we have
 224          * initialized AMU support and enabled invariance. The AMU counters will
 225          * keep on working just fine in the absence of the cpufreq driver, and
 226          * for the CPUs for which there are no counters available, the last set
 227          * value of arch_freq_scale will remain valid as that is the frequency
 228          * those CPUs are running at.
 229          */
 230
 231         return 0;
 232 }
 233
 234 static struct notifier_block init_amu_fie_notifier = {
 235         .notifier_call = init_amu_fie_callback,
 236 };
 237
 238 static int __init init_amu_fie(void)
 239 {
 240         int ret;
 241
 242         if (!zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL))
 243                 return -ENOMEM;
 244
 245         ret = cpufreq_register_notifier(&init_amu_fie_notifier,
 246                                         CPUFREQ_POLICY_NOTIFIER);
 247         if (ret)
 248                 free_cpumask_var(amu_fie_cpus);
 249
 250         return ret;
 251 }
 252 core_initcall(init_amu_fie);
 253
 254 #ifdef CONFIG_ACPI_CPPC_LIB
 255 #include <acpi/cppc_acpi.h>
 256
 257 static void cpu_read_corecnt(void *val)
 258 {
 259         /*
 260          * A value of 0 can be returned if the current CPU does not support AMUs
 261          * or if the counter is disabled for this CPU. A return value of 0 at
 262          * counter read is properly handled as an error case by the users of the
 263          * counter.
 264          */
 265         *(u64 *)val = read_corecnt();
 266 }
 267
 268 static void cpu_read_constcnt(void *val)
 269 {
 270         /*
 271          * Return 0 if the current CPU is affected by erratum 2457168. A value
 272          * of 0 is also returned if the current CPU does not support AMUs or if
 273          * the counter is disabled. A return value of 0 at counter read is
 274          * properly handled as an error case by the users of the counter.
 275          */
 276         *(u64 *)val = this_cpu_has_cap(ARM64_WORKAROUND_2457168) ?
 277                       0UL : read_constcnt();
 278 }
 279
 280 static inline
 281 int counters_read_on_cpu(int cpu, smp_call_func_t func, u64 *val)
 282 {
 283         /*
 284          * Abort call on counterless CPU or when interrupts are
 285          * disabled - can lead to deadlock in smp sync call.
 286          */
 287         if (!cpu_has_amu_feat(cpu))
 288                 return -EOPNOTSUPP;
 289
 290         if (WARN_ON_ONCE(irqs_disabled()))
 291                 return -EPERM;
 292
 293         smp_call_function_single(cpu, func, val, 1);
 294
 295         return 0;
 296 }
 297
 298 /*
 299  * Refer to drivers/acpi/cppc_acpi.c for the description of the functions
 300  * below.
 301  */
 302 bool cpc_ffh_supported(void)
 303 {
 304         int cpu = get_cpu_with_amu_feat();
 305
 306         /*
 307          * FFH is considered supported if there is at least one present CPU that
 308          * supports AMUs. Using FFH to read core and reference counters for CPUs
 309          * that do not support AMUs, have counters disabled or that are affected
 310          * by errata, will result in a return value of 0.
 311          *
 312          * This is done to allow any enabled and valid counters to be read
 313          * through FFH, knowing that potentially returning 0 as counter value is
 314          * properly handled by the users of these counters.
 315          */
 316         if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask))
 317                 return false;
 318
 319         return true;
 320 }
 321
 322 int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val)
 323 {
 324         int ret = -EOPNOTSUPP;
 325
 326         switch ((u64)reg->address) {
 327         case 0x0:
 328                 ret = counters_read_on_cpu(cpu, cpu_read_corecnt, val);
 329                 break;
 330         case 0x1:
 331                 ret = counters_read_on_cpu(cpu, cpu_read_constcnt, val);
 332                 break;
 333         }
 334
 335         if (!ret) {
 336                 *val &= GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
 337                                     reg->bit_offset);
 338                 *val >>= reg->bit_offset;
 339         }
 340
 341         return ret;
 342 }
 343
 344 int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
 345 {
 346         return -EOPNOTSUPP;
 347 }
 348 #endif /* CONFIG_ACPI_CPPC_LIB */