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 static int component_devices_open(struct inode *inode, struct file *file) 89 { 90 return single_open(file, component_devices_show, inode->i_private); 91 } 92 93 static const struct file_operations component_devices_fops = { 94 .open = component_devices_open, 95 .read = seq_read, 96 .llseek = seq_lseek, 97 .release = single_release, 98 }; 99 100 static int __init component_debug_init(void) 101 { 102 component_debugfs_dir = debugfs_create_dir("device_component", NULL); 103 104 return 0; 105 } 106 107 core_initcall(component_debug_init); 108 109 static void component_master_debugfs_add(struct master *m) 110 { 111 m->dentry = debugfs_create_file(dev_name(m->dev), 0444, 112 component_debugfs_dir, 113 m, &component_devices_fops); 114 } 115 116 static void component_master_debugfs_del(struct master *m) 117 { 118 debugfs_remove(m->dentry); 119 m->dentry = NULL; 120 } 121 122 #else 123 124 static void component_master_debugfs_add(struct master *m) 125 { } 126 127 static void component_master_debugfs_del(struct master *m) 128 { } 129 130 #endif 131 132 static struct master *__master_find(struct device *dev, 133 const struct component_master_ops *ops) 134 { 135 struct master *m; 136 137 list_for_each_entry(m, &masters, node) 138 if (m->dev == dev && (!ops || m->ops == ops)) 139 return m; 140 141 return NULL; 142 } 143 144 static struct component *find_component(struct master *master, 145 int (*compare)(struct device *, void *), void *compare_data) 146 { 147 struct component *c; 148 149 list_for_each_entry(c, &component_list, node) { 150 if (c->master && c->master != master) 151 continue; 152 153 if (compare(c->dev, compare_data)) 154 return c; 155 } 156 157 return NULL; 158 } 159 160 static int find_components(struct master *master) 161 { 162 struct component_match *match = master->match; 163 size_t i; 164 int ret = 0; 165 166 /* 167 * Scan the array of match functions and attach 168 * any components which are found to this master. 169 */ 170 for (i = 0; i < match->num; i++) { 171 struct component_match_array *mc = &match->compare[i]; 172 struct component *c; 173 174 dev_dbg(master->dev, "Looking for component %zu\n", i); 175 176 if (match->compare[i].component) 177 continue; 178 179 c = find_component(master, mc->compare, mc->data); 180 if (!c) { 181 ret = -ENXIO; 182 break; 183 } 184 185 dev_dbg(master->dev, "found component %s, duplicate %u\n", dev_name(c->dev), !!c->master); 186 187 /* Attach this component to the master */ 188 match->compare[i].duplicate = !!c->master; 189 match->compare[i].component = c; 190 c->master = master; 191 } 192 return ret; 193 } 194 195 /* Detach component from associated master */ 196 static void remove_component(struct master *master, struct component *c) 197 { 198 size_t i; 199 200 /* Detach the component from this master. */ 201 for (i = 0; i < master->match->num; i++) 202 if (master->match->compare[i].component == c) 203 master->match->compare[i].component = NULL; 204 } 205 206 /* 207 * Try to bring up a master. If component is NULL, we're interested in 208 * this master, otherwise it's a component which must be present to try 209 * and bring up the master. 210 * 211 * Returns 1 for successful bringup, 0 if not ready, or -ve errno. 212 */ 213 static int try_to_bring_up_master(struct master *master, 214 struct component *component) 215 { 216 int ret; 217 218 dev_dbg(master->dev, "trying to bring up master\n"); 219 220 if (find_components(master)) { 221 dev_dbg(master->dev, "master has incomplete components\n"); 222 return 0; 223 } 224 225 if (component && component->master != master) { 226 dev_dbg(master->dev, "master is not for this component (%s)\n", 227 dev_name(component->dev)); 228 return 0; 229 } 230 231 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 232 return -ENOMEM; 233 234 /* Found all components */ 235 ret = master->ops->bind(master->dev); 236 if (ret < 0) { 237 devres_release_group(master->dev, NULL); 238 dev_info(master->dev, "master bind failed: %d\n", ret); 239 return ret; 240 } 241 242 master->bound = true; 243 return 1; 244 } 245 246 static int try_to_bring_up_masters(struct component *component) 247 { 248 struct master *m; 249 int ret = 0; 250 251 list_for_each_entry(m, &masters, node) { 252 if (!m->bound) { 253 ret = try_to_bring_up_master(m, component); 254 if (ret != 0) 255 break; 256 } 257 } 258 259 return ret; 260 } 261 262 static void take_down_master(struct master *master) 263 { 264 if (master->bound) { 265 master->ops->unbind(master->dev); 266 devres_release_group(master->dev, NULL); 267 master->bound = false; 268 } 269 } 270 271 static void component_match_release(struct device *master, 272 struct component_match *match) 273 { 274 unsigned int i; 275 276 for (i = 0; i < match->num; i++) { 277 struct component_match_array *mc = &match->compare[i]; 278 279 if (mc->release) 280 mc->release(master, mc->data); 281 } 282 283 kfree(match->compare); 284 } 285 286 static void devm_component_match_release(struct device *dev, void *res) 287 { 288 component_match_release(dev, res); 289 } 290 291 static int component_match_realloc(struct device *dev, 292 struct component_match *match, size_t num) 293 { 294 struct component_match_array *new; 295 296 if (match->alloc == num) 297 return 0; 298 299 new = kmalloc_array(num, sizeof(*new), GFP_KERNEL); 300 if (!new) 301 return -ENOMEM; 302 303 if (match->compare) { 304 memcpy(new, match->compare, sizeof(*new) * 305 min(match->num, num)); 306 kfree(match->compare); 307 } 308 match->compare = new; 309 match->alloc = num; 310 311 return 0; 312 } 313 314 /* 315 * Add a component to be matched, with a release function. 316 * 317 * The match array is first created or extended if necessary. 318 */ 319 void component_match_add_release(struct device *master, 320 struct component_match **matchptr, 321 void (*release)(struct device *, void *), 322 int (*compare)(struct device *, void *), void *compare_data) 323 { 324 struct component_match *match = *matchptr; 325 326 if (IS_ERR(match)) 327 return; 328 329 if (!match) { 330 match = devres_alloc(devm_component_match_release, 331 sizeof(*match), GFP_KERNEL); 332 if (!match) { 333 *matchptr = ERR_PTR(-ENOMEM); 334 return; 335 } 336 337 devres_add(master, match); 338 339 *matchptr = match; 340 } 341 342 if (match->num == match->alloc) { 343 size_t new_size = match->alloc + 16; 344 int ret; 345 346 ret = component_match_realloc(master, match, new_size); 347 if (ret) { 348 *matchptr = ERR_PTR(ret); 349 return; 350 } 351 } 352 353 match->compare[match->num].compare = compare; 354 match->compare[match->num].release = release; 355 match->compare[match->num].data = compare_data; 356 match->compare[match->num].component = NULL; 357 match->num++; 358 } 359 EXPORT_SYMBOL(component_match_add_release); 360 361 static void free_master(struct master *master) 362 { 363 struct component_match *match = master->match; 364 int i; 365 366 component_master_debugfs_del(master); 367 list_del(&master->node); 368 369 if (match) { 370 for (i = 0; i < match->num; i++) { 371 struct component *c = match->compare[i].component; 372 if (c) 373 c->master = NULL; 374 } 375 } 376 377 kfree(master); 378 } 379 380 int component_master_add_with_match(struct device *dev, 381 const struct component_master_ops *ops, 382 struct component_match *match) 383 { 384 struct master *master; 385 int ret; 386 387 /* Reallocate the match array for its true size */ 388 ret = component_match_realloc(dev, match, match->num); 389 if (ret) 390 return ret; 391 392 master = kzalloc(sizeof(*master), GFP_KERNEL); 393 if (!master) 394 return -ENOMEM; 395 396 master->dev = dev; 397 master->ops = ops; 398 master->match = match; 399 400 component_master_debugfs_add(master); 401 /* Add to the list of available masters. */ 402 mutex_lock(&component_mutex); 403 list_add(&master->node, &masters); 404 405 ret = try_to_bring_up_master(master, NULL); 406 407 if (ret < 0) 408 free_master(master); 409 410 mutex_unlock(&component_mutex); 411 412 return ret < 0 ? ret : 0; 413 } 414 EXPORT_SYMBOL_GPL(component_master_add_with_match); 415 416 void component_master_del(struct device *dev, 417 const struct component_master_ops *ops) 418 { 419 struct master *master; 420 421 mutex_lock(&component_mutex); 422 master = __master_find(dev, ops); 423 if (master) { 424 take_down_master(master); 425 free_master(master); 426 } 427 mutex_unlock(&component_mutex); 428 } 429 EXPORT_SYMBOL_GPL(component_master_del); 430 431 static void component_unbind(struct component *component, 432 struct master *master, void *data) 433 { 434 WARN_ON(!component->bound); 435 436 component->ops->unbind(component->dev, master->dev, data); 437 component->bound = false; 438 439 /* Release all resources claimed in the binding of this component */ 440 devres_release_group(component->dev, component); 441 } 442 443 void component_unbind_all(struct device *master_dev, void *data) 444 { 445 struct master *master; 446 struct component *c; 447 size_t i; 448 449 WARN_ON(!mutex_is_locked(&component_mutex)); 450 451 master = __master_find(master_dev, NULL); 452 if (!master) 453 return; 454 455 /* Unbind components in reverse order */ 456 for (i = master->match->num; i--; ) 457 if (!master->match->compare[i].duplicate) { 458 c = master->match->compare[i].component; 459 component_unbind(c, master, data); 460 } 461 } 462 EXPORT_SYMBOL_GPL(component_unbind_all); 463 464 static int component_bind(struct component *component, struct master *master, 465 void *data) 466 { 467 int ret; 468 469 /* 470 * Each component initialises inside its own devres group. 471 * This allows us to roll-back a failed component without 472 * affecting anything else. 473 */ 474 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 475 return -ENOMEM; 476 477 /* 478 * Also open a group for the device itself: this allows us 479 * to release the resources claimed against the sub-device 480 * at the appropriate moment. 481 */ 482 if (!devres_open_group(component->dev, component, GFP_KERNEL)) { 483 devres_release_group(master->dev, NULL); 484 return -ENOMEM; 485 } 486 487 dev_dbg(master->dev, "binding %s (ops %ps)\n", 488 dev_name(component->dev), component->ops); 489 490 ret = component->ops->bind(component->dev, master->dev, data); 491 if (!ret) { 492 component->bound = true; 493 494 /* 495 * Close the component device's group so that resources 496 * allocated in the binding are encapsulated for removal 497 * at unbind. Remove the group on the DRM device as we 498 * can clean those resources up independently. 499 */ 500 devres_close_group(component->dev, NULL); 501 devres_remove_group(master->dev, NULL); 502 503 dev_info(master->dev, "bound %s (ops %ps)\n", 504 dev_name(component->dev), component->ops); 505 } else { 506 devres_release_group(component->dev, NULL); 507 devres_release_group(master->dev, NULL); 508 509 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n", 510 dev_name(component->dev), component->ops, ret); 511 } 512 513 return ret; 514 } 515 516 int component_bind_all(struct device *master_dev, void *data) 517 { 518 struct master *master; 519 struct component *c; 520 size_t i; 521 int ret = 0; 522 523 WARN_ON(!mutex_is_locked(&component_mutex)); 524 525 master = __master_find(master_dev, NULL); 526 if (!master) 527 return -EINVAL; 528 529 /* Bind components in match order */ 530 for (i = 0; i < master->match->num; i++) 531 if (!master->match->compare[i].duplicate) { 532 c = master->match->compare[i].component; 533 ret = component_bind(c, master, data); 534 if (ret) 535 break; 536 } 537 538 if (ret != 0) { 539 for (; i--; ) 540 if (!master->match->compare[i].duplicate) { 541 c = master->match->compare[i].component; 542 component_unbind(c, master, data); 543 } 544 } 545 546 return ret; 547 } 548 EXPORT_SYMBOL_GPL(component_bind_all); 549 550 int component_add(struct device *dev, const struct component_ops *ops) 551 { 552 struct component *component; 553 int ret; 554 555 component = kzalloc(sizeof(*component), GFP_KERNEL); 556 if (!component) 557 return -ENOMEM; 558 559 component->ops = ops; 560 component->dev = dev; 561 562 dev_dbg(dev, "adding component (ops %ps)\n", ops); 563 564 mutex_lock(&component_mutex); 565 list_add_tail(&component->node, &component_list); 566 567 ret = try_to_bring_up_masters(component); 568 if (ret < 0) { 569 if (component->master) 570 remove_component(component->master, component); 571 list_del(&component->node); 572 573 kfree(component); 574 } 575 mutex_unlock(&component_mutex); 576 577 return ret < 0 ? ret : 0; 578 } 579 EXPORT_SYMBOL_GPL(component_add); 580 581 void component_del(struct device *dev, const struct component_ops *ops) 582 { 583 struct component *c, *component = NULL; 584 585 mutex_lock(&component_mutex); 586 list_for_each_entry(c, &component_list, node) 587 if (c->dev == dev && c->ops == ops) { 588 list_del(&c->node); 589 component = c; 590 break; 591 } 592 593 if (component && component->master) { 594 take_down_master(component->master); 595 remove_component(component->master, component); 596 } 597 598 mutex_unlock(&component_mutex); 599 600 WARN_ON(!component); 601 kfree(component); 602 } 603 EXPORT_SYMBOL_GPL(component_del); 604 605 MODULE_LICENSE("GPL v2"); 606