arch/arc/kernel/perf_event.c

   1 /*
   2  * Linux performance counter support for ARC700 series
   3  *
   4  * Copyright (C) 2013 Synopsys, Inc. (www.synopsys.com)
   5  *
   6  * This code is inspired by the perf support of various other architectures.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  */
  13 #include <linux/errno.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/perf_event.h>
  17 #include <linux/platform_device.h>
  18 #include <asm/arcregs.h>
  19
  20 struct arc_pmu {
  21         struct pmu      pmu;
  22         int             counter_size;   /* in bits */
  23         int             n_counters;
  24         unsigned long   used_mask[BITS_TO_LONGS(ARC_PMU_MAX_HWEVENTS)];
  25         int             ev_hw_idx[PERF_COUNT_ARC_HW_MAX];
  26 };
  27
  28 /* read counter #idx; note that counter# != event# on ARC! */
  29 static uint64_t arc_pmu_read_counter(int idx)
  30 {
  31         uint32_t tmp;
  32         uint64_t result;
  33
  34         /*
  35          * ARC supports making 'snapshots' of the counters, so we don't
  36          * need to care about counters wrapping to 0 underneath our feet
  37          */
  38         write_aux_reg(ARC_REG_PCT_INDEX, idx);
  39         tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
  40         write_aux_reg(ARC_REG_PCT_CONTROL, tmp | ARC_REG_PCT_CONTROL_SN);
  41         result = (uint64_t) (read_aux_reg(ARC_REG_PCT_SNAPH)) << 32;
  42         result |= read_aux_reg(ARC_REG_PCT_SNAPL);
  43
  44         return result;
  45 }
  46
  47 static void arc_perf_event_update(struct perf_event *event,
  48                                   struct hw_perf_event *hwc, int idx)
  49 {
  50         struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
  51         uint64_t prev_raw_count, new_raw_count;
  52         int64_t delta;
  53
  54         do {
  55                 prev_raw_count = local64_read(&hwc->prev_count);
  56                 new_raw_count = arc_pmu_read_counter(idx);
  57         } while (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
  58                                  new_raw_count) != prev_raw_count);
  59
  60         delta = (new_raw_count - prev_raw_count) &
  61                 ((1ULL << arc_pmu->counter_size) - 1ULL);
  62
  63         local64_add(delta, &event->count);
  64         local64_sub(delta, &hwc->period_left);
  65 }
  66
  67 static void arc_pmu_read(struct perf_event *event)
  68 {
  69         arc_perf_event_update(event, &event->hw, event->hw.idx);
  70 }
  71
  72 static int arc_pmu_cache_event(u64 config)
  73 {
  74         unsigned int cache_type, cache_op, cache_result;
  75         int ret;
  76
  77         cache_type      = (config >>  0) & 0xff;
  78         cache_op        = (config >>  8) & 0xff;
  79         cache_result    = (config >> 16) & 0xff;
  80         if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
  81                 return -EINVAL;
  82         if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
  83                 return -EINVAL;
  84         if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
  85                 return -EINVAL;
  86
  87         ret = arc_pmu_cache_map[cache_type][cache_op][cache_result];
  88
  89         if (ret == CACHE_OP_UNSUPPORTED)
  90                 return -ENOENT;
  91
  92         return ret;
  93 }
  94
  95 /* initializes hw_perf_event structure if event is supported */
  96 static int arc_pmu_event_init(struct perf_event *event)
  97 {
  98         struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
  99         struct hw_perf_event *hwc = &event->hw;
 100         int ret;
 101
 102         switch (event->attr.type) {
 103         case PERF_TYPE_HARDWARE:
 104                 if (event->attr.config >= PERF_COUNT_HW_MAX)
 105                         return -ENOENT;
 106                 if (arc_pmu->ev_hw_idx[event->attr.config] < 0)
 107                         return -ENOENT;
 108                 hwc->config = arc_pmu->ev_hw_idx[event->attr.config];
 109                 pr_debug("initializing event %d with cfg %d\n",
 110                          (int) event->attr.config, (int) hwc->config);
 111                 return 0;
 112         case PERF_TYPE_HW_CACHE:
 113                 ret = arc_pmu_cache_event(event->attr.config);
 114                 if (ret < 0)
 115                         return ret;
 116                 hwc->config = arc_pmu->ev_hw_idx[ret];
 117                 return 0;
 118         default:
 119                 return -ENOENT;
 120         }
 121 }
 122
 123 /* starts all counters */
 124 static void arc_pmu_enable(struct pmu *pmu)
 125 {
 126         uint32_t tmp;
 127         tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
 128         write_aux_reg(ARC_REG_PCT_CONTROL, (tmp & 0xffff0000) | 0x1);
 129 }
 130
 131 /* stops all counters */
 132 static void arc_pmu_disable(struct pmu *pmu)
 133 {
 134         uint32_t tmp;
 135         tmp = read_aux_reg(ARC_REG_PCT_CONTROL);
 136         write_aux_reg(ARC_REG_PCT_CONTROL, (tmp & 0xffff0000) | 0x0);
 137 }
 138
 139 /*
 140  * Assigns hardware counter to hardware condition.
 141  * Note that there is no separate start/stop mechanism;
 142  * stopping is achieved by assigning the 'never' condition
 143  */
 144 static void arc_pmu_start(struct perf_event *event, int flags)
 145 {
 146         struct hw_perf_event *hwc = &event->hw;
 147         int idx = hwc->idx;
 148
 149         if (WARN_ON_ONCE(idx == -1))
 150                 return;
 151
 152         if (flags & PERF_EF_RELOAD)
 153                 WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
 154
 155         event->hw.state = 0;
 156
 157         /* enable ARC pmu here */
 158         write_aux_reg(ARC_REG_PCT_INDEX, idx);
 159         write_aux_reg(ARC_REG_PCT_CONFIG, hwc->config);
 160 }
 161
 162 static void arc_pmu_stop(struct perf_event *event, int flags)
 163 {
 164         struct hw_perf_event *hwc = &event->hw;
 165         int idx = hwc->idx;
 166
 167         if (!(event->hw.state & PERF_HES_STOPPED)) {
 168                 /* stop ARC pmu here */
 169                 write_aux_reg(ARC_REG_PCT_INDEX, idx);
 170
 171                 /* condition code #0 is always "never" */
 172                 write_aux_reg(ARC_REG_PCT_CONFIG, 0);
 173
 174                 event->hw.state |= PERF_HES_STOPPED;
 175         }
 176
 177         if ((flags & PERF_EF_UPDATE) &&
 178             !(event->hw.state & PERF_HES_UPTODATE)) {
 179                 arc_perf_event_update(event, &event->hw, idx);
 180                 event->hw.state |= PERF_HES_UPTODATE;
 181         }
 182 }
 183
 184 static void arc_pmu_del(struct perf_event *event, int flags)
 185 {
 186         struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
 187
 188         arc_pmu_stop(event, PERF_EF_UPDATE);
 189         __clear_bit(event->hw.idx, arc_pmu->used_mask);
 190
 191         perf_event_update_userpage(event);
 192 }
 193
 194 /* allocate hardware counter and optionally start counting */
 195 static int arc_pmu_add(struct perf_event *event, int flags)
 196 {
 197         struct arc_pmu *arc_pmu = container_of(event->pmu, struct arc_pmu, pmu);
 198         struct hw_perf_event *hwc = &event->hw;
 199         int idx = hwc->idx;
 200
 201         if (__test_and_set_bit(idx, arc_pmu->used_mask)) {
 202                 idx = find_first_zero_bit(arc_pmu->used_mask,
 203                                           arc_pmu->n_counters);
 204                 if (idx == arc_pmu->n_counters)
 205                         return -EAGAIN;
 206
 207                 __set_bit(idx, arc_pmu->used_mask);
 208                 hwc->idx = idx;
 209         }
 210
 211         write_aux_reg(ARC_REG_PCT_INDEX, idx);
 212         write_aux_reg(ARC_REG_PCT_CONFIG, 0);
 213         write_aux_reg(ARC_REG_PCT_COUNTL, 0);
 214         write_aux_reg(ARC_REG_PCT_COUNTH, 0);
 215         local64_set(&hwc->prev_count, 0);
 216
 217         hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
 218         if (flags & PERF_EF_START)
 219                 arc_pmu_start(event, PERF_EF_RELOAD);
 220
 221         perf_event_update_userpage(event);
 222
 223         return 0;
 224 }
 225
 226 static int arc_pmu_device_probe(struct platform_device *pdev)
 227 {
 228         struct arc_pmu *arc_pmu;
 229         struct arc_reg_pct_build pct_bcr;
 230         struct arc_reg_cc_build cc_bcr;
 231         int i, j, ret;
 232
 233         union cc_name {
 234                 struct {
 235                         uint32_t word0, word1;
 236                         char sentinel;
 237                 } indiv;
 238                 char str[9];
 239         } cc_name;
 240
 241
 242         READ_BCR(ARC_REG_PCT_BUILD, pct_bcr);
 243         if (!pct_bcr.v) {
 244                 pr_err("This core does not have performance counters!\n");
 245                 return -ENODEV;
 246         }
 247
 248         arc_pmu = devm_kzalloc(&pdev->dev, sizeof(struct arc_pmu),
 249                                GFP_KERNEL);
 250         if (!arc_pmu)
 251                 return -ENOMEM;
 252
 253         arc_pmu->n_counters = pct_bcr.c;
 254         BUG_ON(arc_pmu->n_counters > ARC_PMU_MAX_HWEVENTS);
 255
 256         arc_pmu->counter_size = 32 + (pct_bcr.s << 4);
 257         pr_info("ARC PMU found with %d counters of size %d bits\n",
 258                 arc_pmu->n_counters, arc_pmu->counter_size);
 259
 260         READ_BCR(ARC_REG_CC_BUILD, cc_bcr);
 261
 262         if (!cc_bcr.v)
 263                 pr_err("Strange! Performance counters exist, but no countable conditions?\n");
 264
 265         pr_info("ARC PMU has %d countable conditions\n", cc_bcr.c);
 266
 267         cc_name.str[8] = 0;
 268         for (i = 0; i < PERF_COUNT_HW_MAX; i++)
 269                 arc_pmu->ev_hw_idx[i] = -1;
 270
 271         for (j = 0; j < cc_bcr.c; j++) {
 272                 write_aux_reg(ARC_REG_CC_INDEX, j);
 273                 cc_name.indiv.word0 = read_aux_reg(ARC_REG_CC_NAME0);
 274                 cc_name.indiv.word1 = read_aux_reg(ARC_REG_CC_NAME1);
 275                 for (i = 0; i < ARRAY_SIZE(arc_pmu_ev_hw_map); i++) {
 276                         if (arc_pmu_ev_hw_map[i] &&
 277                             !strcmp(arc_pmu_ev_hw_map[i], cc_name.str) &&
 278                             strlen(arc_pmu_ev_hw_map[i])) {
 279                                 pr_debug("mapping %d to idx %d with name %s\n",
 280                                          i, j, cc_name.str);
 281                                 arc_pmu->ev_hw_idx[i] = j;
 282                         }
 283                 }
 284         }
 285
 286         arc_pmu->pmu = (struct pmu) {
 287                 .pmu_enable     = arc_pmu_enable,
 288                 .pmu_disable    = arc_pmu_disable,
 289                 .event_init     = arc_pmu_event_init,
 290                 .add            = arc_pmu_add,
 291                 .del            = arc_pmu_del,
 292                 .start          = arc_pmu_start,
 293                 .stop           = arc_pmu_stop,
 294                 .read           = arc_pmu_read,
 295         };
 296
 297         /* ARC 700 PMU does not support sampling events */
 298         arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
 299
 300         ret = perf_pmu_register(&arc_pmu->pmu, pdev->name, PERF_TYPE_RAW);
 301
 302         return ret;
 303 }
 304
 305 #ifdef CONFIG_OF
 306 static const struct of_device_id arc_pmu_match[] = {
 307         { .compatible = "snps,arc700-pmu" },
 308         {},
 309 };
 310 MODULE_DEVICE_TABLE(of, arc_pmu_match);
 311 #endif
 312
 313 static struct platform_driver arc_pmu_driver = {
 314         .driver = {
 315                 .name           = "arc700-pmu",
 316                 .of_match_table = of_match_ptr(arc_pmu_match),
 317         },
 318         .probe          = arc_pmu_device_probe,
 319 };
 320
 321 module_platform_driver(arc_pmu_driver);
 322
 323 MODULE_LICENSE("GPL");
 324 MODULE_AUTHOR("Mischa Jonker <mjonker@synopsys.com>");
 325 MODULE_DESCRIPTION("ARC PMU driver");