1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Componentized device handling. 4 * 5 * This is work in progress. We gather up the component devices into a list, 6 * and bind them when instructed. At the moment, we're specific to the DRM 7 * subsystem, and only handles one master device, but this doesn't have to be 8 * the case. 9 */ 10 #include <linux/component.h> 11 #include <linux/device.h> 12 #include <linux/kref.h> 13 #include <linux/list.h> 14 #include <linux/module.h> 15 #include <linux/mutex.h> 16 #include <linux/slab.h> 17 #include <linux/debugfs.h> 18 19 struct component; 20 21 struct component_match_array { 22 void *data; 23 int (*compare)(struct device *, void *); 24 void (*release)(struct device *, void *); 25 struct component *component; 26 bool duplicate; 27 }; 28 29 struct component_match { 30 size_t alloc; 31 size_t num; 32 struct component_match_array *compare; 33 }; 34 35 struct master { 36 struct list_head node; 37 bool bound; 38 39 const struct component_master_ops *ops; 40 struct device *dev; 41 struct component_match *match; 42 struct dentry *dentry; 43 }; 44 45 struct component { 46 struct list_head node; 47 struct master *master; 48 bool bound; 49 50 const struct component_ops *ops; 51 struct device *dev; 52 }; 53 54 static DEFINE_MUTEX(component_mutex); 55 static LIST_HEAD(component_list); 56 static LIST_HEAD(masters); 57 58 #ifdef CONFIG_DEBUG_FS 59 60 static struct dentry *component_debugfs_dir; 61 62 static int component_devices_show(struct seq_file *s, void *data) 63 { 64 struct master *m = s->private; 65 struct component_match *match = m->match; 66 size_t i; 67 68 mutex_lock(&component_mutex); 69 seq_printf(s, "%-40s %20s\n", "master name", "status"); 70 seq_puts(s, "-------------------------------------------------------------\n"); 71 seq_printf(s, "%-40s %20s\n\n", 72 dev_name(m->dev), m->bound ? "bound" : "not bound"); 73 74 seq_printf(s, "%-40s %20s\n", "device name", "status"); 75 seq_puts(s, "-------------------------------------------------------------\n"); 76 for (i = 0; i < match->num; i++) { 77 struct device *d = (struct device *)match->compare[i].data; 78 79 seq_printf(s, "%-40s %20s\n", dev_name(d), 80 match->compare[i].component ? 81 "registered" : "not registered"); 82 } 83 mutex_unlock(&component_mutex); 84 85 return 0; 86 } 87 88 DEFINE_SHOW_ATTRIBUTE(component_devices); 89 90 static int __init component_debug_init(void) 91 { 92 component_debugfs_dir = debugfs_create_dir("device_component", NULL); 93 94 return 0; 95 } 96 97 core_initcall(component_debug_init); 98 99 static void component_master_debugfs_add(struct master *m) 100 { 101 m->dentry = debugfs_create_file(dev_name(m->dev), 0444, 102 component_debugfs_dir, 103 m, &component_devices_fops); 104 } 105 106 static void component_master_debugfs_del(struct master *m) 107 { 108 debugfs_remove(m->dentry); 109 m->dentry = NULL; 110 } 111 112 #else 113 114 static void component_master_debugfs_add(struct master *m) 115 { } 116 117 static void component_master_debugfs_del(struct master *m) 118 { } 119 120 #endif 121 122 static struct master *__master_find(struct device *dev, 123 const struct component_master_ops *ops) 124 { 125 struct master *m; 126 127 list_for_each_entry(m, &masters, node) 128 if (m->dev == dev && (!ops || m->ops == ops)) 129 return m; 130 131 return NULL; 132 } 133 134 static struct component *find_component(struct master *master, 135 int (*compare)(struct device *, void *), void *compare_data) 136 { 137 struct component *c; 138 139 list_for_each_entry(c, &component_list, node) { 140 if (c->master && c->master != master) 141 continue; 142 143 if (compare(c->dev, compare_data)) 144 return c; 145 } 146 147 return NULL; 148 } 149 150 static int find_components(struct master *master) 151 { 152 struct component_match *match = master->match; 153 size_t i; 154 int ret = 0; 155 156 /* 157 * Scan the array of match functions and attach 158 * any components which are found to this master. 159 */ 160 for (i = 0; i < match->num; i++) { 161 struct component_match_array *mc = &match->compare[i]; 162 struct component *c; 163 164 dev_dbg(master->dev, "Looking for component %zu\n", i); 165 166 if (match->compare[i].component) 167 continue; 168 169 c = find_component(master, mc->compare, mc->data); 170 if (!c) { 171 ret = -ENXIO; 172 break; 173 } 174 175 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master); 176 177 /* Attach this component to the master */ 178 match->compare[i].duplicate = !!c->master; 179 match->compare[i].component = c; 180 c->master = master; 181 } 182 return ret; 183 } 184 185 /* Detach component from associated master */ 186 static void remove_component(struct master *master, struct component *c) 187 { 188 size_t i; 189 190 /* Detach the component from this master. */ 191 for (i = 0; i < master->match->num; i++) 192 if (master->match->compare[i].component == c) 193 master->match->compare[i].component = NULL; 194 } 195 196 /* 197 * Try to bring up a master. If component is NULL, we're interested in 198 * this master, otherwise it's a component which must be present to try 199 * and bring up the master. 200 * 201 * Returns 1 for successful bringup, 0 if not ready, or -ve errno. 202 */ 203 static int try_to_bring_up_master(struct master *master, 204 struct component *component) 205 { 206 int ret; 207 208 dev_dbg(master->dev, "trying to bring up master\n"); 209 210 if (find_components(master)) { 211 dev_dbg(master->dev, "master has incomplete components\n"); 212 return 0; 213 } 214 215 if (component && component->master != master) { 216 dev_dbg(master->dev, "master is not for this component (%s)\n", 217 dev_name(component->dev)); 218 return 0; 219 } 220 221 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 222 return -ENOMEM; 223 224 /* Found all components */ 225 ret = master->ops->bind(master->dev); 226 if (ret < 0) { 227 devres_release_group(master->dev, NULL); 228 dev_info(master->dev, "master bind failed: %d\n", ret); 229 return ret; 230 } 231 232 master->bound = true; 233 return 1; 234 } 235 236 static int try_to_bring_up_masters(struct component *component) 237 { 238 struct master *m; 239 int ret = 0; 240 241 list_for_each_entry(m, &masters, node) { 242 if (!m->bound) { 243 ret = try_to_bring_up_master(m, component); 244 if (ret != 0) 245 break; 246 } 247 } 248 249 return ret; 250 } 251 252 static void take_down_master(struct master *master) 253 { 254 if (master->bound) { 255 master->ops->unbind(master->dev); 256 devres_release_group(master->dev, NULL); 257 master->bound = false; 258 } 259 } 260 261 static void component_match_release(struct device *master, 262 struct component_match *match) 263 { 264 unsigned int i; 265 266 for (i = 0; i < match->num; i++) { 267 struct component_match_array *mc = &match->compare[i]; 268 269 if (mc->release) 270 mc->release(master, mc->data); 271 } 272 273 kfree(match->compare); 274 } 275 276 static void devm_component_match_release(struct device *dev, void *res) 277 { 278 component_match_release(dev, res); 279 } 280 281 static int component_match_realloc(struct device *dev, 282 struct component_match *match, size_t num) 283 { 284 struct component_match_array *new; 285 286 if (match->alloc == num) 287 return 0; 288 289 new = kmalloc_array(num, sizeof(*new), GFP_KERNEL); 290 if (!new) 291 return -ENOMEM; 292 293 if (match->compare) { 294 memcpy(new, match->compare, sizeof(*new) * 295 min(match->num, num)); 296 kfree(match->compare); 297 } 298 match->compare = new; 299 match->alloc = num; 300 301 return 0; 302 } 303 304 /* 305 * Add a component to be matched, with a release function. 306 * 307 * The match array is first created or extended if necessary. 308 */ 309 void component_match_add_release(struct device *master, 310 struct component_match **matchptr, 311 void (*release)(struct device *, void *), 312 int (*compare)(struct device *, void *), void *compare_data) 313 { 314 struct component_match *match = *matchptr; 315 316 if (IS_ERR(match)) 317 return; 318 319 if (!match) { 320 match = devres_alloc(devm_component_match_release, 321 sizeof(*match), GFP_KERNEL); 322 if (!match) { 323 *matchptr = ERR_PTR(-ENOMEM); 324 return; 325 } 326 327 devres_add(master, match); 328 329 *matchptr = match; 330 } 331 332 if (match->num == match->alloc) { 333 size_t new_size = match->alloc + 16; 334 int ret; 335 336 ret = component_match_realloc(master, match, new_size); 337 if (ret) { 338 *matchptr = ERR_PTR(ret); 339 return; 340 } 341 } 342 343 match->compare[match->num].compare = compare; 344 match->compare[match->num].release = release; 345 match->compare[match->num].data = compare_data; 346 match->compare[match->num].component = NULL; 347 match->num++; 348 } 349 EXPORT_SYMBOL(component_match_add_release); 350 351 static void free_master(struct master *master) 352 { 353 struct component_match *match = master->match; 354 int i; 355 356 component_master_debugfs_del(master); 357 list_del(&master->node); 358 359 if (match) { 360 for (i = 0; i < match->num; i++) { 361 struct component *c = match->compare[i].component; 362 if (c) 363 c->master = NULL; 364 } 365 } 366 367 kfree(master); 368 } 369 370 int component_master_add_with_match(struct device *dev, 371 const struct component_master_ops *ops, 372 struct component_match *match) 373 { 374 struct master *master; 375 int ret; 376 377 /* Reallocate the match array for its true size */ 378 ret = component_match_realloc(dev, match, match->num); 379 if (ret) 380 return ret; 381 382 master = kzalloc(sizeof(*master), GFP_KERNEL); 383 if (!master) 384 return -ENOMEM; 385 386 master->dev = dev; 387 master->ops = ops; 388 master->match = match; 389 390 component_master_debugfs_add(master); 391 /* Add to the list of available masters. */ 392 mutex_lock(&component_mutex); 393 list_add(&master->node, &masters); 394 395 ret = try_to_bring_up_master(master, NULL); 396 397 if (ret < 0) 398 free_master(master); 399 400 mutex_unlock(&component_mutex); 401 402 return ret < 0 ? ret : 0; 403 } 404 EXPORT_SYMBOL_GPL(component_master_add_with_match); 405 406 void component_master_del(struct device *dev, 407 const struct component_master_ops *ops) 408 { 409 struct master *master; 410 411 mutex_lock(&component_mutex); 412 master = __master_find(dev, ops); 413 if (master) { 414 take_down_master(master); 415 free_master(master); 416 } 417 mutex_unlock(&component_mutex); 418 } 419 EXPORT_SYMBOL_GPL(component_master_del); 420 421 static void component_unbind(struct component *component, 422 struct master *master, void *data) 423 { 424 WARN_ON(!component->bound); 425 426 component->ops->unbind(component->dev, master->dev, data); 427 component->bound = false; 428 429 /* Release all resources claimed in the binding of this component */ 430 devres_release_group(component->dev, component); 431 } 432 433 void component_unbind_all(struct device *master_dev, void *data) 434 { 435 struct master *master; 436 struct component *c; 437 size_t i; 438 439 WARN_ON(!mutex_is_locked(&component_mutex)); 440 441 master = __master_find(master_dev, NULL); 442 if (!master) 443 return; 444 445 /* Unbind components in reverse order */ 446 for (i = master->match->num; i--; ) 447 if (!master->match->compare[i].duplicate) { 448 c = master->match->compare[i].component; 449 component_unbind(c, master, data); 450 } 451 } 452 EXPORT_SYMBOL_GPL(component_unbind_all); 453 454 static int component_bind(struct component *component, struct master *master, 455 void *data) 456 { 457 int ret; 458 459 /* 460 * Each component initialises inside its own devres group. 461 * This allows us to roll-back a failed component without 462 * affecting anything else. 463 */ 464 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 465 return -ENOMEM; 466 467 /* 468 * Also open a group for the device itself: this allows us 469 * to release the resources claimed against the sub-device 470 * at the appropriate moment. 471 */ 472 if (!devres_open_group(component->dev, component, GFP_KERNEL)) { 473 devres_release_group(master->dev, NULL); 474 return -ENOMEM; 475 } 476 477 dev_dbg(master->dev, "binding %s (ops %ps)\n", 478 dev_name(component->dev), component->ops); 479 480 ret = component->ops->bind(component->dev, master->dev, data); 481 if (!ret) { 482 component->bound = true; 483 484 /* 485 * Close the component device's group so that resources 486 * allocated in the binding are encapsulated for removal 487 * at unbind. Remove the group on the DRM device as we 488 * can clean those resources up independently. 489 */ 490 devres_close_group(component->dev, NULL); 491 devres_remove_group(master->dev, NULL); 492 493 dev_info(master->dev, "bound %s (ops %ps)\n", 494 dev_name(component->dev), component->ops); 495 } else { 496 devres_release_group(component->dev, NULL); 497 devres_release_group(master->dev, NULL); 498 499 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n", 500 dev_name(component->dev), component->ops, ret); 501 } 502 503 return ret; 504 } 505 506 int component_bind_all(struct device *master_dev, void *data) 507 { 508 struct master *master; 509 struct component *c; 510 size_t i; 511 int ret = 0; 512 513 WARN_ON(!mutex_is_locked(&component_mutex)); 514 515 master = __master_find(master_dev, NULL); 516 if (!master) 517 return -EINVAL; 518 519 /* Bind components in match order */ 520 for (i = 0; i < master->match->num; i++) 521 if (!master->match->compare[i].duplicate) { 522 c = master->match->compare[i].component; 523 ret = component_bind(c, master, data); 524 if (ret) 525 break; 526 } 527 528 if (ret != 0) { 529 for (; i > 0; i--) 530 if (!master->match->compare[i - 1].duplicate) { 531 c = master->match->compare[i - 1].component; 532 component_unbind(c, master, data); 533 } 534 } 535 536 return ret; 537 } 538 EXPORT_SYMBOL_GPL(component_bind_all); 539 540 int component_add(struct device *dev, const struct component_ops *ops) 541 { 542 struct component *component; 543 int ret; 544 545 component = kzalloc(sizeof(*component), GFP_KERNEL); 546 if (!component) 547 return -ENOMEM; 548 549 component->ops = ops; 550 component->dev = dev; 551 552 dev_dbg(dev, "adding component (ops %ps)\n", ops); 553 554 mutex_lock(&component_mutex); 555 list_add_tail(&component->node, &component_list); 556 557 ret = try_to_bring_up_masters(component); 558 if (ret < 0) { 559 if (component->master) 560 remove_component(component->master, component); 561 list_del(&component->node); 562 563 kfree(component); 564 } 565 mutex_unlock(&component_mutex); 566 567 return ret < 0 ? ret : 0; 568 } 569 EXPORT_SYMBOL_GPL(component_add); 570 571 void component_del(struct device *dev, const struct component_ops *ops) 572 { 573 struct component *c, *component = NULL; 574 575 mutex_lock(&component_mutex); 576 list_for_each_entry(c, &component_list, node) 577 if (c->dev == dev && c->ops == ops) { 578 list_del(&c->node); 579 component = c; 580 break; 581 } 582 583 if (component && component->master) { 584 take_down_master(component->master); 585 remove_component(component->master, component); 586 } 587 588 mutex_unlock(&component_mutex); 589 590 WARN_ON(!component); 591 kfree(component); 592 } 593 EXPORT_SYMBOL_GPL(component_del); 594 595 MODULE_LICENSE("GPL v2"); 596