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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 | ||
9e1ccb4a RK |
136 | if (!devres_open_group(master->dev, NULL, GFP_KERNEL)) { |
137 | ret = -ENOMEM; | |
138 | goto out; | |
139 | } | |
140 | ||
2a41e607 RK |
141 | /* Found all components */ |
142 | ret = master->ops->bind(master->dev); | |
143 | if (ret < 0) { | |
9e1ccb4a RK |
144 | devres_release_group(master->dev, NULL); |
145 | dev_info(master->dev, "master bind failed: %d\n", ret); | |
2a41e607 RK |
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); | |
9e1ccb4a | 176 | devres_release_group(master->dev, NULL); |
2a41e607 RK |
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"); |