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 } 210 211 static void devm_component_match_release(struct device *dev, void *res) 212 { 213 component_match_release(dev, res); 214 } 215 216 static int component_match_realloc(struct device *dev, 217 struct component_match *match, size_t num) 218 { 219 struct component_match_array *new; 220 221 if (match->alloc == num) 222 return 0; 223 224 new = devm_kmalloc_array(dev, num, sizeof(*new), GFP_KERNEL); 225 if (!new) 226 return -ENOMEM; 227 228 if (match->compare) { 229 memcpy(new, match->compare, sizeof(*new) * 230 min(match->num, num)); 231 devm_kfree(dev, match->compare); 232 } 233 match->compare = new; 234 match->alloc = num; 235 236 return 0; 237 } 238 239 /* 240 * Add a component to be matched, with a release function. 241 * 242 * The match array is first created or extended if necessary. 243 */ 244 void component_match_add_release(struct device *master, 245 struct component_match **matchptr, 246 void (*release)(struct device *, void *), 247 int (*compare)(struct device *, void *), void *compare_data) 248 { 249 struct component_match *match = *matchptr; 250 251 if (IS_ERR(match)) 252 return; 253 254 if (!match) { 255 match = devres_alloc(devm_component_match_release, 256 sizeof(*match), GFP_KERNEL); 257 if (!match) { 258 *matchptr = ERR_PTR(-ENOMEM); 259 return; 260 } 261 262 devres_add(master, match); 263 264 *matchptr = match; 265 } 266 267 if (match->num == match->alloc) { 268 size_t new_size = match ? match->alloc + 16 : 15; 269 int ret; 270 271 ret = component_match_realloc(master, match, new_size); 272 if (ret) { 273 *matchptr = ERR_PTR(ret); 274 return; 275 } 276 } 277 278 match->compare[match->num].compare = compare; 279 match->compare[match->num].release = release; 280 match->compare[match->num].data = compare_data; 281 match->compare[match->num].component = NULL; 282 match->num++; 283 } 284 EXPORT_SYMBOL(component_match_add_release); 285 286 int component_master_add_with_match(struct device *dev, 287 const struct component_master_ops *ops, 288 struct component_match *match) 289 { 290 struct master *master; 291 int ret; 292 293 /* Reallocate the match array for its true size */ 294 ret = component_match_realloc(dev, match, match->num); 295 if (ret) 296 return ret; 297 298 master = kzalloc(sizeof(*master), GFP_KERNEL); 299 if (!master) 300 return -ENOMEM; 301 302 master->dev = dev; 303 master->ops = ops; 304 master->match = match; 305 306 /* Add to the list of available masters. */ 307 mutex_lock(&component_mutex); 308 list_add(&master->node, &masters); 309 310 ret = try_to_bring_up_master(master, NULL); 311 312 if (ret < 0) { 313 /* Delete off the list if we weren't successful */ 314 list_del(&master->node); 315 kfree(master); 316 } 317 mutex_unlock(&component_mutex); 318 319 return ret < 0 ? ret : 0; 320 } 321 EXPORT_SYMBOL_GPL(component_master_add_with_match); 322 323 void component_master_del(struct device *dev, 324 const struct component_master_ops *ops) 325 { 326 struct master *master; 327 int i; 328 329 mutex_lock(&component_mutex); 330 master = __master_find(dev, ops); 331 if (master) { 332 struct component_match *match = master->match; 333 334 take_down_master(master); 335 336 list_del(&master->node); 337 338 if (match) { 339 for (i = 0; i < match->num; i++) { 340 struct component *c = match->compare[i].component; 341 if (c) 342 c->master = NULL; 343 } 344 } 345 kfree(master); 346 } 347 mutex_unlock(&component_mutex); 348 } 349 EXPORT_SYMBOL_GPL(component_master_del); 350 351 static void component_unbind(struct component *component, 352 struct master *master, void *data) 353 { 354 WARN_ON(!component->bound); 355 356 component->ops->unbind(component->dev, master->dev, data); 357 component->bound = false; 358 359 /* Release all resources claimed in the binding of this component */ 360 devres_release_group(component->dev, component); 361 } 362 363 void component_unbind_all(struct device *master_dev, void *data) 364 { 365 struct master *master; 366 struct component *c; 367 size_t i; 368 369 WARN_ON(!mutex_is_locked(&component_mutex)); 370 371 master = __master_find(master_dev, NULL); 372 if (!master) 373 return; 374 375 /* Unbind components in reverse order */ 376 for (i = master->match->num; i--; ) 377 if (!master->match->compare[i].duplicate) { 378 c = master->match->compare[i].component; 379 component_unbind(c, master, data); 380 } 381 } 382 EXPORT_SYMBOL_GPL(component_unbind_all); 383 384 static int component_bind(struct component *component, struct master *master, 385 void *data) 386 { 387 int ret; 388 389 /* 390 * Each component initialises inside its own devres group. 391 * This allows us to roll-back a failed component without 392 * affecting anything else. 393 */ 394 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 395 return -ENOMEM; 396 397 /* 398 * Also open a group for the device itself: this allows us 399 * to release the resources claimed against the sub-device 400 * at the appropriate moment. 401 */ 402 if (!devres_open_group(component->dev, component, GFP_KERNEL)) { 403 devres_release_group(master->dev, NULL); 404 return -ENOMEM; 405 } 406 407 dev_dbg(master->dev, "binding %s (ops %ps)\n", 408 dev_name(component->dev), component->ops); 409 410 ret = component->ops->bind(component->dev, master->dev, data); 411 if (!ret) { 412 component->bound = true; 413 414 /* 415 * Close the component device's group so that resources 416 * allocated in the binding are encapsulated for removal 417 * at unbind. Remove the group on the DRM device as we 418 * can clean those resources up independently. 419 */ 420 devres_close_group(component->dev, NULL); 421 devres_remove_group(master->dev, NULL); 422 423 dev_info(master->dev, "bound %s (ops %ps)\n", 424 dev_name(component->dev), component->ops); 425 } else { 426 devres_release_group(component->dev, NULL); 427 devres_release_group(master->dev, NULL); 428 429 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n", 430 dev_name(component->dev), component->ops, ret); 431 } 432 433 return ret; 434 } 435 436 int component_bind_all(struct device *master_dev, void *data) 437 { 438 struct master *master; 439 struct component *c; 440 size_t i; 441 int ret = 0; 442 443 WARN_ON(!mutex_is_locked(&component_mutex)); 444 445 master = __master_find(master_dev, NULL); 446 if (!master) 447 return -EINVAL; 448 449 /* Bind components in match order */ 450 for (i = 0; i < master->match->num; i++) 451 if (!master->match->compare[i].duplicate) { 452 c = master->match->compare[i].component; 453 ret = component_bind(c, master, data); 454 if (ret) 455 break; 456 } 457 458 if (ret != 0) { 459 for (; i--; ) 460 if (!master->match->compare[i].duplicate) { 461 c = master->match->compare[i].component; 462 component_unbind(c, master, data); 463 } 464 } 465 466 return ret; 467 } 468 EXPORT_SYMBOL_GPL(component_bind_all); 469 470 int component_add(struct device *dev, const struct component_ops *ops) 471 { 472 struct component *component; 473 int ret; 474 475 component = kzalloc(sizeof(*component), GFP_KERNEL); 476 if (!component) 477 return -ENOMEM; 478 479 component->ops = ops; 480 component->dev = dev; 481 482 dev_dbg(dev, "adding component (ops %ps)\n", ops); 483 484 mutex_lock(&component_mutex); 485 list_add_tail(&component->node, &component_list); 486 487 ret = try_to_bring_up_masters(component); 488 if (ret < 0) { 489 list_del(&component->node); 490 491 kfree(component); 492 } 493 mutex_unlock(&component_mutex); 494 495 return ret < 0 ? ret : 0; 496 } 497 EXPORT_SYMBOL_GPL(component_add); 498 499 void component_del(struct device *dev, const struct component_ops *ops) 500 { 501 struct component *c, *component = NULL; 502 503 mutex_lock(&component_mutex); 504 list_for_each_entry(c, &component_list, node) 505 if (c->dev == dev && c->ops == ops) { 506 list_del(&c->node); 507 component = c; 508 break; 509 } 510 511 if (component && component->master) { 512 take_down_master(component->master); 513 remove_component(component->master, component); 514 } 515 516 mutex_unlock(&component_mutex); 517 518 WARN_ON(!component); 519 kfree(component); 520 } 521 EXPORT_SYMBOL_GPL(component_del); 522 523 MODULE_LICENSE("GPL v2"); 524