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