xref: /openbmc/linux/drivers/connector/connector.c (revision 9ac8d3fb) 
1 /*
2  * 	connector.c
3  *
4  * 2004-2005 Copyright (c) Evgeniy Polyakov <johnpol@2ka.mipt.ru>
5  * All rights reserved.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  */
21 
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/list.h>
25 #include <linux/skbuff.h>
26 #include <linux/netlink.h>
27 #include <linux/moduleparam.h>
28 #include <linux/connector.h>
29 #include <linux/mutex.h>
30 #include <linux/proc_fs.h>
31 #include <linux/spinlock.h>
32 
33 #include <net/sock.h>
34 
35 MODULE_LICENSE("GPL");
36 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
37 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
38 
39 static u32 cn_idx = CN_IDX_CONNECTOR;
40 static u32 cn_val = CN_VAL_CONNECTOR;
41 
42 module_param(cn_idx, uint, 0);
43 module_param(cn_val, uint, 0);
44 MODULE_PARM_DESC(cn_idx, "Connector's main device idx.");
45 MODULE_PARM_DESC(cn_val, "Connector's main device val.");
46 
47 static DEFINE_MUTEX(notify_lock);
48 static LIST_HEAD(notify_list);
49 
50 static struct cn_dev cdev;
51 
52 static int cn_already_initialized;
53 
54 /*
55  * msg->seq and msg->ack are used to determine message genealogy.
56  * When someone sends message it puts there locally unique sequence
57  * and random acknowledge numbers.  Sequence number may be copied into
58  * nlmsghdr->nlmsg_seq too.
59  *
60  * Sequence number is incremented with each message to be sent.
61  *
62  * If we expect reply to our message then the sequence number in
63  * received message MUST be the same as in original message, and
64  * acknowledge number MUST be the same + 1.
65  *
66  * If we receive a message and its sequence number is not equal to the
67  * one we are expecting then it is a new message.
68  *
69  * If we receive a message and its sequence number is the same as one
70  * we are expecting but it's acknowledgement number is not equal to
71  * the acknowledgement number in the original message + 1, then it is
72  * a new message.
73  *
74  */
75 int cn_netlink_send(struct cn_msg *msg, u32 __group, gfp_t gfp_mask)
76 {
77 	struct cn_callback_entry *__cbq;
78 	unsigned int size;
79 	struct sk_buff *skb;
80 	struct nlmsghdr *nlh;
81 	struct cn_msg *data;
82 	struct cn_dev *dev = &cdev;
83 	u32 group = 0;
84 	int found = 0;
85 
86 	if (!__group) {
87 		spin_lock_bh(&dev->cbdev->queue_lock);
88 		list_for_each_entry(__cbq, &dev->cbdev->queue_list,
89 				    callback_entry) {
90 			if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
91 				found = 1;
92 				group = __cbq->group;
93 				break;
94 			}
95 		}
96 		spin_unlock_bh(&dev->cbdev->queue_lock);
97 
98 		if (!found)
99 			return -ENODEV;
100 	} else {
101 		group = __group;
102 	}
103 
104 	if (!netlink_has_listeners(dev->nls, group))
105 		return -ESRCH;
106 
107 	size = NLMSG_SPACE(sizeof(*msg) + msg->len);
108 
109 	skb = alloc_skb(size, gfp_mask);
110 	if (!skb)
111 		return -ENOMEM;
112 
113 	nlh = NLMSG_PUT(skb, 0, msg->seq, NLMSG_DONE, size - sizeof(*nlh));
114 
115 	data = NLMSG_DATA(nlh);
116 
117 	memcpy(data, msg, sizeof(*data) + msg->len);
118 
119 	NETLINK_CB(skb).dst_group = group;
120 
121 	return netlink_broadcast(dev->nls, skb, 0, group, gfp_mask);
122 
123 nlmsg_failure:
124 	kfree_skb(skb);
125 	return -EINVAL;
126 }
127 EXPORT_SYMBOL_GPL(cn_netlink_send);
128 
129 /*
130  * Callback helper - queues work and setup destructor for given data.
131  */
132 static int cn_call_callback(struct cn_msg *msg, void (*destruct_data)(void *), void *data)
133 {
134 	struct cn_callback_entry *__cbq, *__new_cbq;
135 	struct cn_dev *dev = &cdev;
136 	int err = -ENODEV;
137 
138 	spin_lock_bh(&dev->cbdev->queue_lock);
139 	list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
140 		if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
141 			if (likely(!work_pending(&__cbq->work) &&
142 					__cbq->data.ddata == NULL)) {
143 				__cbq->data.callback_priv = msg;
144 
145 				__cbq->data.ddata = data;
146 				__cbq->data.destruct_data = destruct_data;
147 
148 				if (queue_work(dev->cbdev->cn_queue,
149 							&__cbq->work))
150 					err = 0;
151 				else
152 					err = -EINVAL;
153 			} else {
154 				struct cn_callback_data *d;
155 
156 				err = -ENOMEM;
157 				__new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
158 				if (__new_cbq) {
159 					d = &__new_cbq->data;
160 					d->callback_priv = msg;
161 					d->callback = __cbq->data.callback;
162 					d->ddata = data;
163 					d->destruct_data = destruct_data;
164 					d->free = __new_cbq;
165 
166 					INIT_WORK(&__new_cbq->work,
167 							&cn_queue_wrapper);
168 
169 					if (queue_work(dev->cbdev->cn_queue,
170 						    &__new_cbq->work))
171 						err = 0;
172 					else {
173 						kfree(__new_cbq);
174 						err = -EINVAL;
175 					}
176 				}
177 			}
178 			break;
179 		}
180 	}
181 	spin_unlock_bh(&dev->cbdev->queue_lock);
182 
183 	return err;
184 }
185 
186 /*
187  * Main netlink receiving function.
188  *
189  * It checks skb, netlink header and msg sizes, and calls callback helper.
190  */
191 static void cn_rx_skb(struct sk_buff *__skb)
192 {
193 	struct cn_msg *msg;
194 	struct nlmsghdr *nlh;
195 	int err;
196 	struct sk_buff *skb;
197 
198 	skb = skb_get(__skb);
199 
200 	if (skb->len >= NLMSG_SPACE(0)) {
201 		nlh = nlmsg_hdr(skb);
202 
203 		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
204 		    skb->len < nlh->nlmsg_len ||
205 		    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
206 			kfree_skb(skb);
207 			return;
208 		}
209 
210 		msg = NLMSG_DATA(nlh);
211 		err = cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
212 		if (err < 0)
213 			kfree_skb(skb);
214 	}
215 }
216 
217 /*
218  * Notification routing.
219  *
220  * Gets id and checks if there are notification request for it's idx
221  * and val.  If there are such requests notify the listeners with the
222  * given notify event.
223  *
224  */
225 static void cn_notify(struct cb_id *id, u32 notify_event)
226 {
227 	struct cn_ctl_entry *ent;
228 
229 	mutex_lock(&notify_lock);
230 	list_for_each_entry(ent, &notify_list, notify_entry) {
231 		int i;
232 		struct cn_notify_req *req;
233 		struct cn_ctl_msg *ctl = ent->msg;
234 		int idx_found, val_found;
235 
236 		idx_found = val_found = 0;
237 
238 		req = (struct cn_notify_req *)ctl->data;
239 		for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
240 			if (id->idx >= req->first &&
241 					id->idx < req->first + req->range) {
242 				idx_found = 1;
243 				break;
244 			}
245 		}
246 
247 		for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
248 			if (id->val >= req->first &&
249 					id->val < req->first + req->range) {
250 				val_found = 1;
251 				break;
252 			}
253 		}
254 
255 		if (idx_found && val_found) {
256 			struct cn_msg m = { .ack = notify_event, };
257 
258 			memcpy(&m.id, id, sizeof(m.id));
259 			cn_netlink_send(&m, ctl->group, GFP_KERNEL);
260 		}
261 	}
262 	mutex_unlock(&notify_lock);
263 }
264 
265 /*
266  * Callback add routing - adds callback with given ID and name.
267  * If there is registered callback with the same ID it will not be added.
268  *
269  * May sleep.
270  */
271 int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
272 {
273 	int err;
274 	struct cn_dev *dev = &cdev;
275 
276 	if (!cn_already_initialized)
277 		return -EAGAIN;
278 
279 	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
280 	if (err)
281 		return err;
282 
283 	cn_notify(id, 0);
284 
285 	return 0;
286 }
287 EXPORT_SYMBOL_GPL(cn_add_callback);
288 
289 /*
290  * Callback remove routing - removes callback
291  * with given ID.
292  * If there is no registered callback with given
293  * ID nothing happens.
294  *
295  * May sleep while waiting for reference counter to become zero.
296  */
297 void cn_del_callback(struct cb_id *id)
298 {
299 	struct cn_dev *dev = &cdev;
300 
301 	cn_queue_del_callback(dev->cbdev, id);
302 	cn_notify(id, 1);
303 }
304 EXPORT_SYMBOL_GPL(cn_del_callback);
305 
306 /*
307  * Checks two connector's control messages to be the same.
308  * Returns 1 if they are the same or if the first one is corrupted.
309  */
310 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
311 {
312 	int i;
313 	struct cn_notify_req *req1, *req2;
314 
315 	if (m1->idx_notify_num != m2->idx_notify_num)
316 		return 0;
317 
318 	if (m1->val_notify_num != m2->val_notify_num)
319 		return 0;
320 
321 	if (m1->len != m2->len)
322 		return 0;
323 
324 	if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
325 	    m1->len)
326 		return 1;
327 
328 	req1 = (struct cn_notify_req *)m1->data;
329 	req2 = (struct cn_notify_req *)m2->data;
330 
331 	for (i = 0; i < m1->idx_notify_num; ++i) {
332 		if (req1->first != req2->first || req1->range != req2->range)
333 			return 0;
334 		req1++;
335 		req2++;
336 	}
337 
338 	for (i = 0; i < m1->val_notify_num; ++i) {
339 		if (req1->first != req2->first || req1->range != req2->range)
340 			return 0;
341 		req1++;
342 		req2++;
343 	}
344 
345 	return 1;
346 }
347 
348 /*
349  * Main connector device's callback.
350  *
351  * Used for notification of a request's processing.
352  */
353 static void cn_callback(void *data)
354 {
355 	struct cn_msg *msg = data;
356 	struct cn_ctl_msg *ctl;
357 	struct cn_ctl_entry *ent;
358 	u32 size;
359 
360 	if (msg->len < sizeof(*ctl))
361 		return;
362 
363 	ctl = (struct cn_ctl_msg *)msg->data;
364 
365 	size = (sizeof(*ctl) + ((ctl->idx_notify_num +
366 				 ctl->val_notify_num) *
367 				sizeof(struct cn_notify_req)));
368 
369 	if (msg->len != size)
370 		return;
371 
372 	if (ctl->len + sizeof(*ctl) != msg->len)
373 		return;
374 
375 	/*
376 	 * Remove notification.
377 	 */
378 	if (ctl->group == 0) {
379 		struct cn_ctl_entry *n;
380 
381 		mutex_lock(&notify_lock);
382 		list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
383 			if (cn_ctl_msg_equals(ent->msg, ctl)) {
384 				list_del(&ent->notify_entry);
385 				kfree(ent);
386 			}
387 		}
388 		mutex_unlock(&notify_lock);
389 
390 		return;
391 	}
392 
393 	size += sizeof(*ent);
394 
395 	ent = kzalloc(size, GFP_KERNEL);
396 	if (!ent)
397 		return;
398 
399 	ent->msg = (struct cn_ctl_msg *)(ent + 1);
400 
401 	memcpy(ent->msg, ctl, size - sizeof(*ent));
402 
403 	mutex_lock(&notify_lock);
404 	list_add(&ent->notify_entry, &notify_list);
405 	mutex_unlock(&notify_lock);
406 }
407 
408 static int cn_proc_show(struct seq_file *m, void *v)
409 {
410 	struct cn_queue_dev *dev = cdev.cbdev;
411 	struct cn_callback_entry *cbq;
412 
413 	seq_printf(m, "Name            ID\n");
414 
415 	spin_lock_bh(&dev->queue_lock);
416 
417 	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
418 		seq_printf(m, "%-15s %u:%u\n",
419 			   cbq->id.name,
420 			   cbq->id.id.idx,
421 			   cbq->id.id.val);
422 	}
423 
424 	spin_unlock_bh(&dev->queue_lock);
425 
426 	return 0;
427 }
428 
429 static int cn_proc_open(struct inode *inode, struct file *file)
430 {
431 	return single_open(file, cn_proc_show, NULL);
432 }
433 
434 static const struct file_operations cn_file_ops = {
435 	.owner   = THIS_MODULE,
436 	.open    = cn_proc_open,
437 	.read    = seq_read,
438 	.llseek  = seq_lseek,
439 	.release = single_release
440 };
441 
442 static int __devinit cn_init(void)
443 {
444 	struct cn_dev *dev = &cdev;
445 	int err;
446 
447 	dev->input = cn_rx_skb;
448 	dev->id.idx = cn_idx;
449 	dev->id.val = cn_val;
450 
451 	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
452 					 CN_NETLINK_USERS + 0xf,
453 					 dev->input, NULL, THIS_MODULE);
454 	if (!dev->nls)
455 		return -EIO;
456 
457 	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
458 	if (!dev->cbdev) {
459 		netlink_kernel_release(dev->nls);
460 		return -EINVAL;
461 	}
462 
463 	cn_already_initialized = 1;
464 
465 	err = cn_add_callback(&dev->id, "connector", &cn_callback);
466 	if (err) {
467 		cn_already_initialized = 0;
468 		cn_queue_free_dev(dev->cbdev);
469 		netlink_kernel_release(dev->nls);
470 		return -EINVAL;
471 	}
472 
473 	proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
474 
475 	return 0;
476 }
477 
478 static void __devexit cn_fini(void)
479 {
480 	struct cn_dev *dev = &cdev;
481 
482 	cn_already_initialized = 0;
483 
484 	proc_net_remove(&init_net, "connector");
485 
486 	cn_del_callback(&dev->id);
487 	cn_queue_free_dev(dev->cbdev);
488 	netlink_kernel_release(dev->nls);
489 }
490 
491 subsys_initcall(cn_init);
492 module_exit(cn_fini);
493