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