drivers/hwtracing/coresight/coresight-sysfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2019, Linaro Limited, All rights reserved.
   4  * Author: Mike Leach <[email protected]>
   5  */
   6
   7 #include <linux/device.h>
   8 #include <linux/idr.h>
   9 #include <linux/kernel.h>
  10
  11 #include "coresight-priv.h"
  12 #include "coresight-trace-id.h"
  13
  14 /*
  15  * Use IDR to map the hash of the source's device name
  16  * to the pointer of path for the source. The idr is for
  17  * the sources which aren't associated with CPU.
  18  */
  19 static DEFINE_IDR(path_idr);
  20
  21 /*
  22  * When operating Coresight drivers from the sysFS interface, only a single
  23  * path can exist from a tracer (associated to a CPU) to a sink.
  24  */
  25 static DEFINE_PER_CPU(struct list_head *, tracer_path);
  26
  27 ssize_t coresight_simple_show_pair(struct device *_dev,
  28                               struct device_attribute *attr, char *buf)
  29 {
  30         struct coresight_device *csdev = container_of(_dev, struct coresight_device, dev);
  31         struct cs_pair_attribute *cs_attr = container_of(attr, struct cs_pair_attribute, attr);
  32         u64 val;
  33
  34         pm_runtime_get_sync(_dev->parent);
  35         val = csdev_access_relaxed_read_pair(&csdev->access, cs_attr->lo_off, cs_attr->hi_off);
  36         pm_runtime_put_sync(_dev->parent);
  37         return sysfs_emit(buf, "0x%llx\n", val);
  38 }
  39 EXPORT_SYMBOL_GPL(coresight_simple_show_pair);
  40
  41 ssize_t coresight_simple_show32(struct device *_dev,
  42                               struct device_attribute *attr, char *buf)
  43 {
  44         struct coresight_device *csdev = container_of(_dev, struct coresight_device, dev);
  45         struct cs_off_attribute *cs_attr = container_of(attr, struct cs_off_attribute, attr);
  46         u64 val;
  47
  48         pm_runtime_get_sync(_dev->parent);
  49         val = csdev_access_relaxed_read32(&csdev->access, cs_attr->off);
  50         pm_runtime_put_sync(_dev->parent);
  51         return sysfs_emit(buf, "0x%llx\n", val);
  52 }
  53 EXPORT_SYMBOL_GPL(coresight_simple_show32);
  54
  55 static int coresight_enable_source_sysfs(struct coresight_device *csdev,
  56                                          enum cs_mode mode, void *data)
  57 {
  58         int ret;
  59
  60         /*
  61          * Comparison with CS_MODE_SYSFS works without taking any device
  62          * specific spinlock because the truthyness of that comparison can only
  63          * change with coresight_mutex held, which we already have here.
  64          */
  65         lockdep_assert_held(&coresight_mutex);
  66         if (coresight_get_mode(csdev) != CS_MODE_SYSFS) {
  67                 ret = source_ops(csdev)->enable(csdev, data, mode, NULL);
  68                 if (ret)
  69                         return ret;
  70         }
  71
  72         csdev->refcnt++;
  73
  74         return 0;
  75 }
  76
  77 /**
  78  *  coresight_disable_source_sysfs - Drop the reference count by 1 and disable
  79  *  the device if there are no users left.
  80  *
  81  *  @csdev: The coresight device to disable
  82  *  @data: Opaque data to pass on to the disable function of the source device.
  83  *         For example in perf mode this is a pointer to the struct perf_event.
  84  *
  85  *  Returns true if the device has been disabled.
  86  */
  87 static bool coresight_disable_source_sysfs(struct coresight_device *csdev,
  88                                            void *data)
  89 {
  90         lockdep_assert_held(&coresight_mutex);
  91         if (coresight_get_mode(csdev) != CS_MODE_SYSFS)
  92                 return false;
  93
  94         csdev->refcnt--;
  95         if (csdev->refcnt == 0) {
  96                 coresight_disable_source(csdev, data);
  97                 return true;
  98         }
  99         return false;
 100 }
 101
 102 /**
 103  * coresight_find_activated_sysfs_sink - returns the first sink activated via
 104  * sysfs using connection based search starting from the source reference.
 105  *
 106  * @csdev: Coresight source device reference
 107  */
 108 static struct coresight_device *
 109 coresight_find_activated_sysfs_sink(struct coresight_device *csdev)
 110 {
 111         int i;
 112         struct coresight_device *sink = NULL;
 113
 114         if ((csdev->type == CORESIGHT_DEV_TYPE_SINK ||
 115              csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) &&
 116              csdev->sysfs_sink_activated)
 117                 return csdev;
 118
 119         /*
 120          * Recursively explore each port found on this element.
 121          */
 122         for (i = 0; i < csdev->pdata->nr_outconns; i++) {
 123                 struct coresight_device *child_dev;
 124
 125                 child_dev = csdev->pdata->out_conns[i]->dest_dev;
 126                 if (child_dev)
 127                         sink = coresight_find_activated_sysfs_sink(child_dev);
 128                 if (sink)
 129                         return sink;
 130         }
 131
 132         return NULL;
 133 }
 134
 135 /** coresight_validate_source - make sure a source has the right credentials to
 136  *  be used via sysfs.
 137  *  @csdev:     the device structure for a source.
 138  *  @function:  the function this was called from.
 139  *
 140  * Assumes the coresight_mutex is held.
 141  */
 142 static int coresight_validate_source_sysfs(struct coresight_device *csdev,
 143                                      const char *function)
 144 {
 145         u32 type, subtype;
 146
 147         type = csdev->type;
 148         subtype = csdev->subtype.source_subtype;
 149
 150         if (type != CORESIGHT_DEV_TYPE_SOURCE) {
 151                 dev_err(&csdev->dev, "wrong device type in %s\n", function);
 152                 return -EINVAL;
 153         }
 154
 155         if (subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_PROC &&
 156             subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE &&
 157             subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM &&
 158             subtype != CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS) {
 159                 dev_err(&csdev->dev, "wrong device subtype in %s\n", function);
 160                 return -EINVAL;
 161         }
 162
 163         return 0;
 164 }
 165
 166 int coresight_enable_sysfs(struct coresight_device *csdev)
 167 {
 168         int cpu, ret = 0;
 169         struct coresight_device *sink;
 170         struct list_head *path;
 171         enum coresight_dev_subtype_source subtype;
 172         u32 hash;
 173
 174         subtype = csdev->subtype.source_subtype;
 175
 176         mutex_lock(&coresight_mutex);
 177
 178         ret = coresight_validate_source_sysfs(csdev, __func__);
 179         if (ret)
 180                 goto out;
 181
 182         /*
 183          * mode == SYSFS implies that it's already enabled. Don't look at the
 184          * refcount to determine this because we don't claim the source until
 185          * coresight_enable_source() so can still race with Perf mode which
 186          * doesn't hold coresight_mutex.
 187          */
 188         if (coresight_get_mode(csdev) == CS_MODE_SYSFS) {
 189                 /*
 190                  * There could be multiple applications driving the software
 191                  * source. So keep the refcount for each such user when the
 192                  * source is already enabled.
 193                  */
 194                 if (subtype == CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE)
 195                         csdev->refcnt++;
 196                 goto out;
 197         }
 198
 199         sink = coresight_find_activated_sysfs_sink(csdev);
 200         if (!sink) {
 201                 ret = -EINVAL;
 202                 goto out;
 203         }
 204
 205         path = coresight_build_path(csdev, sink);
 206         if (IS_ERR(path)) {
 207                 pr_err("building path(s) failed\n");
 208                 ret = PTR_ERR(path);
 209                 goto out;
 210         }
 211
 212         ret = coresight_enable_path(path, CS_MODE_SYSFS, NULL);
 213         if (ret)
 214                 goto err_path;
 215
 216         ret = coresight_enable_source_sysfs(csdev, CS_MODE_SYSFS, NULL);
 217         if (ret)
 218                 goto err_source;
 219
 220         switch (subtype) {
 221         case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
 222                 /*
 223                  * When working from sysFS it is important to keep track
 224                  * of the paths that were created so that they can be
 225                  * undone in 'coresight_disable()'.  Since there can only
 226                  * be a single session per tracer (when working from sysFS)
 227                  * a per-cpu variable will do just fine.
 228                  */
 229                 cpu = source_ops(csdev)->cpu_id(csdev);
 230                 per_cpu(tracer_path, cpu) = path;
 231                 break;
 232         case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
 233         case CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM:
 234         case CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS:
 235                 /*
 236                  * Use the hash of source's device name as ID
 237                  * and map the ID to the pointer of the path.
 238                  */
 239                 hash = hashlen_hash(hashlen_string(NULL, dev_name(&csdev->dev)));
 240                 ret = idr_alloc_u32(&path_idr, path, &hash, hash, GFP_KERNEL);
 241                 if (ret)
 242                         goto err_source;
 243                 break;
 244         default:
 245                 /* We can't be here */
 246                 break;
 247         }
 248
 249 out:
 250         mutex_unlock(&coresight_mutex);
 251         return ret;
 252
 253 err_source:
 254         coresight_disable_path(path);
 255
 256 err_path:
 257         coresight_release_path(path);
 258         goto out;
 259 }
 260 EXPORT_SYMBOL_GPL(coresight_enable_sysfs);
 261
 262 void coresight_disable_sysfs(struct coresight_device *csdev)
 263 {
 264         int cpu, ret;
 265         struct list_head *path = NULL;
 266         u32 hash;
 267
 268         mutex_lock(&coresight_mutex);
 269
 270         ret = coresight_validate_source_sysfs(csdev, __func__);
 271         if (ret)
 272                 goto out;
 273
 274         if (!coresight_disable_source_sysfs(csdev, NULL))
 275                 goto out;
 276
 277         switch (csdev->subtype.source_subtype) {
 278         case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:
 279                 cpu = source_ops(csdev)->cpu_id(csdev);
 280                 path = per_cpu(tracer_path, cpu);
 281                 per_cpu(tracer_path, cpu) = NULL;
 282                 break;
 283         case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
 284         case CORESIGHT_DEV_SUBTYPE_SOURCE_TPDM:
 285         case CORESIGHT_DEV_SUBTYPE_SOURCE_OTHERS:
 286                 hash = hashlen_hash(hashlen_string(NULL, dev_name(&csdev->dev)));
 287                 /* Find the path by the hash. */
 288                 path = idr_find(&path_idr, hash);
 289                 if (path == NULL) {
 290                         pr_err("Path is not found for %s\n", dev_name(&csdev->dev));
 291                         goto out;
 292                 }
 293                 idr_remove(&path_idr, hash);
 294                 break;
 295         default:
 296                 /* We can't be here */
 297                 break;
 298         }
 299
 300         coresight_disable_path(path);
 301         coresight_release_path(path);
 302
 303 out:
 304         mutex_unlock(&coresight_mutex);
 305 }
 306 EXPORT_SYMBOL_GPL(coresight_disable_sysfs);
 307
 308 static ssize_t enable_sink_show(struct device *dev,
 309                                 struct device_attribute *attr, char *buf)
 310 {
 311         struct coresight_device *csdev = to_coresight_device(dev);
 312
 313         return scnprintf(buf, PAGE_SIZE, "%u\n", csdev->sysfs_sink_activated);
 314 }
 315
 316 static ssize_t enable_sink_store(struct device *dev,
 317                                  struct device_attribute *attr,
 318                                  const char *buf, size_t size)
 319 {
 320         int ret;
 321         unsigned long val;
 322         struct coresight_device *csdev = to_coresight_device(dev);
 323
 324         ret = kstrtoul(buf, 10, &val);
 325         if (ret)
 326                 return ret;
 327
 328         csdev->sysfs_sink_activated = !!val;
 329
 330         return size;
 331
 332 }
 333 static DEVICE_ATTR_RW(enable_sink);
 334
 335 static ssize_t enable_source_show(struct device *dev,
 336                                   struct device_attribute *attr, char *buf)
 337 {
 338         struct coresight_device *csdev = to_coresight_device(dev);
 339
 340         guard(mutex)(&coresight_mutex);
 341         return scnprintf(buf, PAGE_SIZE, "%u\n",
 342                          coresight_get_mode(csdev) == CS_MODE_SYSFS);
 343 }
 344
 345 static ssize_t enable_source_store(struct device *dev,
 346                                    struct device_attribute *attr,
 347                                    const char *buf, size_t size)
 348 {
 349         int ret = 0;
 350         unsigned long val;
 351         struct coresight_device *csdev = to_coresight_device(dev);
 352
 353         ret = kstrtoul(buf, 10, &val);
 354         if (ret)
 355                 return ret;
 356
 357         if (val) {
 358                 ret = coresight_enable_sysfs(csdev);
 359                 if (ret)
 360                         return ret;
 361         } else {
 362                 coresight_disable_sysfs(csdev);
 363         }
 364
 365         return size;
 366 }
 367 static DEVICE_ATTR_RW(enable_source);
 368
 369 static struct attribute *coresight_sink_attrs[] = {
 370         &dev_attr_enable_sink.attr,
 371         NULL,
 372 };
 373 ATTRIBUTE_GROUPS(coresight_sink);
 374
 375 static struct attribute *coresight_source_attrs[] = {
 376         &dev_attr_enable_source.attr,
 377         NULL,
 378 };
 379 ATTRIBUTE_GROUPS(coresight_source);
 380
 381 const struct device_type coresight_dev_type[] = {
 382         [CORESIGHT_DEV_TYPE_SINK] = {
 383                 .name = "sink",
 384                 .groups = coresight_sink_groups,
 385         },
 386         [CORESIGHT_DEV_TYPE_LINK] = {
 387                 .name = "link",
 388         },
 389         [CORESIGHT_DEV_TYPE_LINKSINK] = {
 390                 .name = "linksink",
 391                 .groups = coresight_sink_groups,
 392         },
 393         [CORESIGHT_DEV_TYPE_SOURCE] = {
 394                 .name = "source",
 395                 .groups = coresight_source_groups,
 396         },
 397         [CORESIGHT_DEV_TYPE_HELPER] = {
 398                 .name = "helper",
 399         }
 400 };
 401 /* Ensure the enum matches the names and groups */
 402 static_assert(ARRAY_SIZE(coresight_dev_type) == CORESIGHT_DEV_TYPE_MAX);
 403
 404 /*
 405  * Connections group - links attribute.
 406  * Count of created links between coresight components in the group.
 407  */
 408 static ssize_t nr_links_show(struct device *dev,
 409                              struct device_attribute *attr,
 410                              char *buf)
 411 {
 412         struct coresight_device *csdev = to_coresight_device(dev);
 413
 414         return sprintf(buf, "%d\n", csdev->nr_links);
 415 }
 416 static DEVICE_ATTR_RO(nr_links);
 417
 418 static struct attribute *coresight_conns_attrs[] = {
 419         &dev_attr_nr_links.attr,
 420         NULL,
 421 };
 422
 423 static struct attribute_group coresight_conns_group = {
 424         .attrs = coresight_conns_attrs,
 425         .name = "connections",
 426 };
 427
 428 /*
 429  * Create connections group for CoreSight devices.
 430  * This group will then be used to collate the sysfs links between
 431  * devices.
 432  */
 433 int coresight_create_conns_sysfs_group(struct coresight_device *csdev)
 434 {
 435         int ret = 0;
 436
 437         if (!csdev)
 438                 return -EINVAL;
 439
 440         ret = sysfs_create_group(&csdev->dev.kobj, &coresight_conns_group);
 441         if (ret)
 442                 return ret;
 443
 444         csdev->has_conns_grp = true;
 445         return ret;
 446 }
 447
 448 void coresight_remove_conns_sysfs_group(struct coresight_device *csdev)
 449 {
 450         if (!csdev)
 451                 return;
 452
 453         if (csdev->has_conns_grp) {
 454                 sysfs_remove_group(&csdev->dev.kobj, &coresight_conns_group);
 455                 csdev->has_conns_grp = false;
 456         }
 457 }
 458
 459 int coresight_add_sysfs_link(struct coresight_sysfs_link *info)
 460 {
 461         int ret = 0;
 462
 463         if (!info)
 464                 return -EINVAL;
 465         if (!info->orig || !info->target ||
 466             !info->orig_name || !info->target_name)
 467                 return -EINVAL;
 468         if (!info->orig->has_conns_grp || !info->target->has_conns_grp)
 469                 return -EINVAL;
 470
 471         /* first link orig->target */
 472         ret = sysfs_add_link_to_group(&info->orig->dev.kobj,
 473                                       coresight_conns_group.name,
 474                                       &info->target->dev.kobj,
 475                                       info->orig_name);
 476         if (ret)
 477                 return ret;
 478
 479         /* second link target->orig */
 480         ret = sysfs_add_link_to_group(&info->target->dev.kobj,
 481                                       coresight_conns_group.name,
 482                                       &info->orig->dev.kobj,
 483                                       info->target_name);
 484
 485         /* error in second link - remove first - otherwise inc counts */
 486         if (ret) {
 487                 sysfs_remove_link_from_group(&info->orig->dev.kobj,
 488                                              coresight_conns_group.name,
 489                                              info->orig_name);
 490         } else {
 491                 info->orig->nr_links++;
 492                 info->target->nr_links++;
 493         }
 494
 495         return ret;
 496 }
 497 EXPORT_SYMBOL_GPL(coresight_add_sysfs_link);
 498
 499 void coresight_remove_sysfs_link(struct coresight_sysfs_link *info)
 500 {
 501         if (!info)
 502                 return;
 503         if (!info->orig || !info->target ||
 504             !info->orig_name || !info->target_name)
 505                 return;
 506
 507         sysfs_remove_link_from_group(&info->orig->dev.kobj,
 508                                      coresight_conns_group.name,
 509                                      info->orig_name);
 510
 511         sysfs_remove_link_from_group(&info->target->dev.kobj,
 512                                      coresight_conns_group.name,
 513                                      info->target_name);
 514
 515         info->orig->nr_links--;
 516         info->target->nr_links--;
 517 }
 518 EXPORT_SYMBOL_GPL(coresight_remove_sysfs_link);
 519
 520 /*
 521  * coresight_make_links: Make a link for a connection from a @orig
 522  * device to @target, represented by @conn.
 523  *
 524  *   e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
 525  *   as two symbolic links :
 526  *
 527  *      /sys/.../devOrig/out:X  -> /sys/.../devTarget/
 528  *      /sys/.../devTarget/in:Y -> /sys/.../devOrig/
 529  *
 530  * The link names are allocated for a device where it appears. i.e, the
 531  * "out" link on the master and "in" link on the slave device.
 532  * The link info is stored in the connection record for avoiding
 533  * the reconstruction of names for removal.
 534  */
 535 int coresight_make_links(struct coresight_device *orig,
 536                          struct coresight_connection *conn,
 537                          struct coresight_device *target)
 538 {
 539         int ret = -ENOMEM;
 540         char *outs = NULL, *ins = NULL;
 541         struct coresight_sysfs_link *link = NULL;
 542
 543         /* Helper devices aren't shown in sysfs */
 544         if (conn->dest_port == -1 && conn->src_port == -1)
 545                 return 0;
 546
 547         do {
 548                 outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
 549                                       "out:%d", conn->src_port);
 550                 if (!outs)
 551                         break;
 552                 ins = devm_kasprintf(&target->dev, GFP_KERNEL,
 553                                      "in:%d", conn->dest_port);
 554                 if (!ins)
 555                         break;
 556                 link = devm_kzalloc(&orig->dev,
 557                                     sizeof(struct coresight_sysfs_link),
 558                                     GFP_KERNEL);
 559                 if (!link)
 560                         break;
 561
 562                 link->orig = orig;
 563                 link->target = target;
 564                 link->orig_name = outs;
 565                 link->target_name = ins;
 566
 567                 ret = coresight_add_sysfs_link(link);
 568                 if (ret)
 569                         break;
 570
 571                 conn->link = link;
 572                 return 0;
 573         } while (0);
 574
 575         return ret;
 576 }
 577
 578 /*
 579  * coresight_remove_links: Remove the sysfs links for a given connection @conn,
 580  * from @orig device to @target device. See coresight_make_links() for more
 581  * details.
 582  */
 583 void coresight_remove_links(struct coresight_device *orig,
 584                             struct coresight_connection *conn)
 585 {
 586         if (!orig || !conn->link)
 587                 return;
 588
 589         coresight_remove_sysfs_link(conn->link);
 590
 591         devm_kfree(&conn->dest_dev->dev, conn->link->target_name);
 592         devm_kfree(&orig->dev, conn->link->orig_name);
 593         devm_kfree(&orig->dev, conn->link);
 594         conn->link = NULL;
 595 }