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 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
 30struct 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
 40static DEFINE_MUTEX(component_mutex);
 41static LIST_HEAD(component_list);
 42static LIST_HEAD(masters);
 43
 44static 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. */
 57static 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. */
 65static void component_detach_master(struct master *master, struct component *c)
 66{
 67	list_del(&c->master_node);
 68
 69	c->master = NULL;
 70}
 71
 72int 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}
 91EXPORT_SYMBOL_GPL(component_master_add_child);
 92
 93/* Detach all attached components from this master */
 94static 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 */
113static 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	}
153out:
154
155	return ret;
156}
157
158static 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
172static 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
183int 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}
212EXPORT_SYMBOL_GPL(component_master_add);
213
214void 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}
229EXPORT_SYMBOL_GPL(component_master_del);
230
231static 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
243void 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}
257EXPORT_SYMBOL_GPL(component_unbind_all);
258
259static 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
311int 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}
337EXPORT_SYMBOL_GPL(component_bind_all);
338
339int 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}
366EXPORT_SYMBOL_GPL(component_add);
367
368void 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}
388EXPORT_SYMBOL_GPL(component_del);
389
390MODULE_LICENSE("GPL v2");