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 master { 22 struct list_head node; 23 struct list_head components; 24 bool bound; 25 26 const struct component_master_ops *ops; 27 struct device *dev; 28 }; 29 30 struct component { 31 struct list_head node; 32 struct list_head master_node; 33 struct master *master; 34 bool bound; 35 36 const struct component_ops *ops; 37 struct device *dev; 38 }; 39 40 static DEFINE_MUTEX(component_mutex); 41 static LIST_HEAD(component_list); 42 static LIST_HEAD(masters); 43 44 static struct master *__master_find(struct device *dev, 45 const struct component_master_ops *ops) 46 { 47 struct master *m; 48 49 list_for_each_entry(m, &masters, node) 50 if (m->dev == dev && (!ops || m->ops == ops)) 51 return m; 52 53 return NULL; 54 } 55 56 /* Attach an unattached component to a master. */ 57 static void component_attach_master(struct master *master, struct component *c) 58 { 59 c->master = master; 60 61 list_add_tail(&c->master_node, &master->components); 62 } 63 64 /* Detach a component from a master. */ 65 static void component_detach_master(struct master *master, struct component *c) 66 { 67 list_del(&c->master_node); 68 69 c->master = NULL; 70 } 71 72 int component_master_add_child(struct master *master, 73 int (*compare)(struct device *, void *), void *compare_data) 74 { 75 struct component *c; 76 int ret = -ENXIO; 77 78 list_for_each_entry(c, &component_list, node) { 79 if (c->master) 80 continue; 81 82 if (compare(c->dev, compare_data)) { 83 component_attach_master(master, c); 84 ret = 0; 85 break; 86 } 87 } 88 89 return ret; 90 } 91 EXPORT_SYMBOL_GPL(component_master_add_child); 92 93 /* Detach all attached components from this master */ 94 static void master_remove_components(struct master *master) 95 { 96 while (!list_empty(&master->components)) { 97 struct component *c = list_first_entry(&master->components, 98 struct component, master_node); 99 100 WARN_ON(c->master != master); 101 102 component_detach_master(master, c); 103 } 104 } 105 106 /* 107 * Try to bring up a master. If component is NULL, we're interested in 108 * this master, otherwise it's a component which must be present to try 109 * and bring up the master. 110 * 111 * Returns 1 for successful bringup, 0 if not ready, or -ve errno. 112 */ 113 static int try_to_bring_up_master(struct master *master, 114 struct component *component) 115 { 116 int ret = 0; 117 118 if (!master->bound) { 119 /* 120 * Search the list of components, looking for components that 121 * belong to this master, and attach them to the master. 122 */ 123 if (master->ops->add_components(master->dev, master)) { 124 /* Failed to find all components */ 125 master_remove_components(master); 126 ret = 0; 127 goto out; 128 } 129 130 if (component && component->master != master) { 131 master_remove_components(master); 132 ret = 0; 133 goto out; 134 } 135 136 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) { 137 ret = -ENOMEM; 138 goto out; 139 } 140 141 /* Found all components */ 142 ret = master->ops->bind(master->dev); 143 if (ret < 0) { 144 devres_release_group(master->dev, NULL); 145 dev_info(master->dev, "master bind failed: %d\n", ret); 146 master_remove_components(master); 147 goto out; 148 } 149 150 master->bound = true; 151 ret = 1; 152 } 153 out: 154 155 return ret; 156 } 157 158 static int try_to_bring_up_masters(struct component *component) 159 { 160 struct master *m; 161 int ret = 0; 162 163 list_for_each_entry(m, &masters, node) { 164 ret = try_to_bring_up_master(m, component); 165 if (ret != 0) 166 break; 167 } 168 169 return ret; 170 } 171 172 static void take_down_master(struct master *master) 173 { 174 if (master->bound) { 175 master->ops->unbind(master->dev); 176 devres_release_group(master->dev, NULL); 177 master->bound = false; 178 } 179 180 master_remove_components(master); 181 } 182 183 int component_master_add(struct device *dev, 184 const struct component_master_ops *ops) 185 { 186 struct master *master; 187 int ret; 188 189 master = kzalloc(sizeof(*master), GFP_KERNEL); 190 if (!master) 191 return -ENOMEM; 192 193 master->dev = dev; 194 master->ops = ops; 195 INIT_LIST_HEAD(&master->components); 196 197 /* Add to the list of available masters. */ 198 mutex_lock(&component_mutex); 199 list_add(&master->node, &masters); 200 201 ret = try_to_bring_up_master(master, NULL); 202 203 if (ret < 0) { 204 /* Delete off the list if we weren't successful */ 205 list_del(&master->node); 206 kfree(master); 207 } 208 mutex_unlock(&component_mutex); 209 210 return ret < 0 ? ret : 0; 211 } 212 EXPORT_SYMBOL_GPL(component_master_add); 213 214 void component_master_del(struct device *dev, 215 const struct component_master_ops *ops) 216 { 217 struct master *master; 218 219 mutex_lock(&component_mutex); 220 master = __master_find(dev, ops); 221 if (master) { 222 take_down_master(master); 223 224 list_del(&master->node); 225 kfree(master); 226 } 227 mutex_unlock(&component_mutex); 228 } 229 EXPORT_SYMBOL_GPL(component_master_del); 230 231 static void component_unbind(struct component *component, 232 struct master *master, void *data) 233 { 234 WARN_ON(!component->bound); 235 236 component->ops->unbind(component->dev, master->dev, data); 237 component->bound = false; 238 239 /* Release all resources claimed in the binding of this component */ 240 devres_release_group(component->dev, component); 241 } 242 243 void component_unbind_all(struct device *master_dev, void *data) 244 { 245 struct master *master; 246 struct component *c; 247 248 WARN_ON(!mutex_is_locked(&component_mutex)); 249 250 master = __master_find(master_dev, NULL); 251 if (!master) 252 return; 253 254 list_for_each_entry_reverse(c, &master->components, master_node) 255 component_unbind(c, master, data); 256 } 257 EXPORT_SYMBOL_GPL(component_unbind_all); 258 259 static int component_bind(struct component *component, struct master *master, 260 void *data) 261 { 262 int ret; 263 264 /* 265 * Each component initialises inside its own devres group. 266 * This allows us to roll-back a failed component without 267 * affecting anything else. 268 */ 269 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 270 return -ENOMEM; 271 272 /* 273 * Also open a group for the device itself: this allows us 274 * to release the resources claimed against the sub-device 275 * at the appropriate moment. 276 */ 277 if (!devres_open_group(component->dev, component, GFP_KERNEL)) { 278 devres_release_group(master->dev, NULL); 279 return -ENOMEM; 280 } 281 282 dev_dbg(master->dev, "binding %s (ops %ps)\n", 283 dev_name(component->dev), component->ops); 284 285 ret = component->ops->bind(component->dev, master->dev, data); 286 if (!ret) { 287 component->bound = true; 288 289 /* 290 * Close the component device's group so that resources 291 * allocated in the binding are encapsulated for removal 292 * at unbind. Remove the group on the DRM device as we 293 * can clean those resources up independently. 294 */ 295 devres_close_group(component->dev, NULL); 296 devres_remove_group(master->dev, NULL); 297 298 dev_info(master->dev, "bound %s (ops %ps)\n", 299 dev_name(component->dev), component->ops); 300 } else { 301 devres_release_group(component->dev, NULL); 302 devres_release_group(master->dev, NULL); 303 304 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n", 305 dev_name(component->dev), component->ops, ret); 306 } 307 308 return ret; 309 } 310 311 int component_bind_all(struct device *master_dev, void *data) 312 { 313 struct master *master; 314 struct component *c; 315 int ret = 0; 316 317 WARN_ON(!mutex_is_locked(&component_mutex)); 318 319 master = __master_find(master_dev, NULL); 320 if (!master) 321 return -EINVAL; 322 323 list_for_each_entry(c, &master->components, master_node) { 324 ret = component_bind(c, master, data); 325 if (ret) 326 break; 327 } 328 329 if (ret != 0) { 330 list_for_each_entry_continue_reverse(c, &master->components, 331 master_node) 332 component_unbind(c, master, data); 333 } 334 335 return ret; 336 } 337 EXPORT_SYMBOL_GPL(component_bind_all); 338 339 int component_add(struct device *dev, const struct component_ops *ops) 340 { 341 struct component *component; 342 int ret; 343 344 component = kzalloc(sizeof(*component), GFP_KERNEL); 345 if (!component) 346 return -ENOMEM; 347 348 component->ops = ops; 349 component->dev = dev; 350 351 dev_dbg(dev, "adding component (ops %ps)\n", ops); 352 353 mutex_lock(&component_mutex); 354 list_add_tail(&component->node, &component_list); 355 356 ret = try_to_bring_up_masters(component); 357 if (ret < 0) { 358 list_del(&component->node); 359 360 kfree(component); 361 } 362 mutex_unlock(&component_mutex); 363 364 return ret < 0 ? ret : 0; 365 } 366 EXPORT_SYMBOL_GPL(component_add); 367 368 void component_del(struct device *dev, const struct component_ops *ops) 369 { 370 struct component *c, *component = NULL; 371 372 mutex_lock(&component_mutex); 373 list_for_each_entry(c, &component_list, node) 374 if (c->dev == dev && c->ops == ops) { 375 list_del(&c->node); 376 component = c; 377 break; 378 } 379 380 if (component && component->master) 381 take_down_master(component->master); 382 383 mutex_unlock(&component_mutex); 384 385 WARN_ON(!component); 386 kfree(component); 387 } 388 EXPORT_SYMBOL_GPL(component_del); 389 390 MODULE_LICENSE("GPL v2"); 391