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
 21struct component;
 22
 23struct 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
 31struct component_match {
 32	size_t alloc;
 33	size_t num;
 34	struct component_match_array *compare;
 35};
 36
 37struct 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
 46struct 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
 55static DEFINE_MUTEX(component_mutex);
 56static LIST_HEAD(component_list);
 57static LIST_HEAD(masters);
 58
 59static 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
 71static 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
 87static 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 */
123static 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 */
140static 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
173static 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
189static 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
198static 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
213static void devm_component_match_release(struct device *dev, void *res)
214{
215	component_match_release(dev, res);
216}
217
218static 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 */
246void 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->alloc + 16;
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}
286EXPORT_SYMBOL(component_match_add_release);
287
288static 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
306int 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}
339EXPORT_SYMBOL_GPL(component_master_add_with_match);
340
341void 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}
354EXPORT_SYMBOL_GPL(component_master_del);
355
356static 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
368void 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}
387EXPORT_SYMBOL_GPL(component_unbind_all);
388
389static 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
441int 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}
473EXPORT_SYMBOL_GPL(component_bind_all);
474
475int 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}
504EXPORT_SYMBOL_GPL(component_add);
505
506void 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}
528EXPORT_SYMBOL_GPL(component_del);
529
530MODULE_LICENSE("GPL v2");