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 /* Found all components */ 137 ret = master->ops->bind(master->dev); 138 if (ret < 0) { 139 master_remove_components(master); 140 goto out; 141 } 142 143 master->bound = true; 144 ret = 1; 145 } 146 out: 147 148 return ret; 149 } 150 151 static int try_to_bring_up_masters(struct component *component) 152 { 153 struct master *m; 154 int ret = 0; 155 156 list_for_each_entry(m, &masters, node) { 157 ret = try_to_bring_up_master(m, component); 158 if (ret != 0) 159 break; 160 } 161 162 return ret; 163 } 164 165 static void take_down_master(struct master *master) 166 { 167 if (master->bound) { 168 master->ops->unbind(master->dev); 169 master->bound = false; 170 } 171 172 master_remove_components(master); 173 } 174 175 int component_master_add(struct device *dev, 176 const struct component_master_ops *ops) 177 { 178 struct master *master; 179 int ret; 180 181 master = kzalloc(sizeof(*master), GFP_KERNEL); 182 if (!master) 183 return -ENOMEM; 184 185 master->dev = dev; 186 master->ops = ops; 187 INIT_LIST_HEAD(&master->components); 188 189 /* Add to the list of available masters. */ 190 mutex_lock(&component_mutex); 191 list_add(&master->node, &masters); 192 193 ret = try_to_bring_up_master(master, NULL); 194 195 if (ret < 0) { 196 /* Delete off the list if we weren't successful */ 197 list_del(&master->node); 198 kfree(master); 199 } 200 mutex_unlock(&component_mutex); 201 202 return ret < 0 ? ret : 0; 203 } 204 EXPORT_SYMBOL_GPL(component_master_add); 205 206 void component_master_del(struct device *dev, 207 const struct component_master_ops *ops) 208 { 209 struct master *master; 210 211 mutex_lock(&component_mutex); 212 master = __master_find(dev, ops); 213 if (master) { 214 take_down_master(master); 215 216 list_del(&master->node); 217 kfree(master); 218 } 219 mutex_unlock(&component_mutex); 220 } 221 EXPORT_SYMBOL_GPL(component_master_del); 222 223 static void component_unbind(struct component *component, 224 struct master *master, void *data) 225 { 226 WARN_ON(!component->bound); 227 228 component->ops->unbind(component->dev, master->dev, data); 229 component->bound = false; 230 231 /* Release all resources claimed in the binding of this component */ 232 devres_release_group(component->dev, component); 233 } 234 235 void component_unbind_all(struct device *master_dev, void *data) 236 { 237 struct master *master; 238 struct component *c; 239 240 WARN_ON(!mutex_is_locked(&component_mutex)); 241 242 master = __master_find(master_dev, NULL); 243 if (!master) 244 return; 245 246 list_for_each_entry_reverse(c, &master->components, master_node) 247 component_unbind(c, master, data); 248 } 249 EXPORT_SYMBOL_GPL(component_unbind_all); 250 251 static int component_bind(struct component *component, struct master *master, 252 void *data) 253 { 254 int ret; 255 256 /* 257 * Each component initialises inside its own devres group. 258 * This allows us to roll-back a failed component without 259 * affecting anything else. 260 */ 261 if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) 262 return -ENOMEM; 263 264 /* 265 * Also open a group for the device itself: this allows us 266 * to release the resources claimed against the sub-device 267 * at the appropriate moment. 268 */ 269 if (!devres_open_group(component->dev, component, GFP_KERNEL)) { 270 devres_release_group(master->dev, NULL); 271 return -ENOMEM; 272 } 273 274 dev_dbg(master->dev, "binding %s (ops %ps)\n", 275 dev_name(component->dev), component->ops); 276 277 ret = component->ops->bind(component->dev, master->dev, data); 278 if (!ret) { 279 component->bound = true; 280 281 /* 282 * Close the component device's group so that resources 283 * allocated in the binding are encapsulated for removal 284 * at unbind. Remove the group on the DRM device as we 285 * can clean those resources up independently. 286 */ 287 devres_close_group(component->dev, NULL); 288 devres_remove_group(master->dev, NULL); 289 290 dev_info(master->dev, "bound %s (ops %ps)\n", 291 dev_name(component->dev), component->ops); 292 } else { 293 devres_release_group(component->dev, NULL); 294 devres_release_group(master->dev, NULL); 295 296 dev_err(master->dev, "failed to bind %s (ops %ps): %d\n", 297 dev_name(component->dev), component->ops, ret); 298 } 299 300 return ret; 301 } 302 303 int component_bind_all(struct device *master_dev, void *data) 304 { 305 struct master *master; 306 struct component *c; 307 int ret = 0; 308 309 WARN_ON(!mutex_is_locked(&component_mutex)); 310 311 master = __master_find(master_dev, NULL); 312 if (!master) 313 return -EINVAL; 314 315 list_for_each_entry(c, &master->components, master_node) { 316 ret = component_bind(c, master, data); 317 if (ret) 318 break; 319 } 320 321 if (ret != 0) { 322 list_for_each_entry_continue_reverse(c, &master->components, 323 master_node) 324 component_unbind(c, master, data); 325 } 326 327 return ret; 328 } 329 EXPORT_SYMBOL_GPL(component_bind_all); 330 331 int component_add(struct device *dev, const struct component_ops *ops) 332 { 333 struct component *component; 334 int ret; 335 336 component = kzalloc(sizeof(*component), GFP_KERNEL); 337 if (!component) 338 return -ENOMEM; 339 340 component->ops = ops; 341 component->dev = dev; 342 343 dev_dbg(dev, "adding component (ops %ps)\n", ops); 344 345 mutex_lock(&component_mutex); 346 list_add_tail(&component->node, &component_list); 347 348 ret = try_to_bring_up_masters(component); 349 if (ret < 0) { 350 list_del(&component->node); 351 352 kfree(component); 353 } 354 mutex_unlock(&component_mutex); 355 356 return ret < 0 ? ret : 0; 357 } 358 EXPORT_SYMBOL_GPL(component_add); 359 360 void component_del(struct device *dev, const struct component_ops *ops) 361 { 362 struct component *c, *component = NULL; 363 364 mutex_lock(&component_mutex); 365 list_for_each_entry(c, &component_list, node) 366 if (c->dev == dev && c->ops == ops) { 367 list_del(&c->node); 368 component = c; 369 break; 370 } 371 372 if (component && component->master) 373 take_down_master(component->master); 374 375 mutex_unlock(&component_mutex); 376 377 WARN_ON(!component); 378 kfree(component); 379 } 380 EXPORT_SYMBOL_GPL(component_del); 381 382 MODULE_LICENSE("GPL v2"); 383