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