xref: /openbmc/linux/drivers/connector/connector.c (revision b04b4f78) 
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_cn_work(__cbq, &__cbq->work))
149 					err = 0;
150 				else
151 					err = -EINVAL;
152 			} else {
153 				struct cn_callback_data *d;
154 
155 				err = -ENOMEM;
156 				__new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
157 				if (__new_cbq) {
158 					d = &__new_cbq->data;
159 					d->callback_priv = msg;
160 					d->callback = __cbq->data.callback;
161 					d->ddata = data;
162 					d->destruct_data = destruct_data;
163 					d->free = __new_cbq;
164 
165 					__new_cbq->pdev = __cbq->pdev;
166 
167 					INIT_WORK(&__new_cbq->work,
168 							&cn_queue_wrapper);
169 
170 					if (queue_cn_work(__new_cbq,
171 						    &__new_cbq->work))
172 						err = 0;
173 					else {
174 						kfree(__new_cbq);
175 						err = -EINVAL;
176 					}
177 				}
178 			}
179 			break;
180 		}
181 	}
182 	spin_unlock_bh(&dev->cbdev->queue_lock);
183 
184 	return err;
185 }
186 
187 /*
188  * Main netlink receiving function.
189  *
190  * It checks skb, netlink header and msg sizes, and calls callback helper.
191  */
192 static void cn_rx_skb(struct sk_buff *__skb)
193 {
194 	struct cn_msg *msg;
195 	struct nlmsghdr *nlh;
196 	int err;
197 	struct sk_buff *skb;
198 
199 	skb = skb_get(__skb);
200 
201 	if (skb->len >= NLMSG_SPACE(0)) {
202 		nlh = nlmsg_hdr(skb);
203 
204 		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
205 		    skb->len < nlh->nlmsg_len ||
206 		    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
207 			kfree_skb(skb);
208 			return;
209 		}
210 
211 		msg = NLMSG_DATA(nlh);
212 		err = cn_call_callback(msg, (void (*)(void *))kfree_skb, skb);
213 		if (err < 0)
214 			kfree_skb(skb);
215 	}
216 }
217 
218 /*
219  * Notification routing.
220  *
221  * Gets id and checks if there are notification request for it's idx
222  * and val.  If there are such requests notify the listeners with the
223  * given notify event.
224  *
225  */
226 static void cn_notify(struct cb_id *id, u32 notify_event)
227 {
228 	struct cn_ctl_entry *ent;
229 
230 	mutex_lock(&notify_lock);
231 	list_for_each_entry(ent, &notify_list, notify_entry) {
232 		int i;
233 		struct cn_notify_req *req;
234 		struct cn_ctl_msg *ctl = ent->msg;
235 		int idx_found, val_found;
236 
237 		idx_found = val_found = 0;
238 
239 		req = (struct cn_notify_req *)ctl->data;
240 		for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
241 			if (id->idx >= req->first &&
242 					id->idx < req->first + req->range) {
243 				idx_found = 1;
244 				break;
245 			}
246 		}
247 
248 		for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
249 			if (id->val >= req->first &&
250 					id->val < req->first + req->range) {
251 				val_found = 1;
252 				break;
253 			}
254 		}
255 
256 		if (idx_found && val_found) {
257 			struct cn_msg m = { .ack = notify_event, };
258 
259 			memcpy(&m.id, id, sizeof(m.id));
260 			cn_netlink_send(&m, ctl->group, GFP_KERNEL);
261 		}
262 	}
263 	mutex_unlock(&notify_lock);
264 }
265 
266 /*
267  * Callback add routing - adds callback with given ID and name.
268  * If there is registered callback with the same ID it will not be added.
269  *
270  * May sleep.
271  */
272 int cn_add_callback(struct cb_id *id, char *name, void (*callback)(void *))
273 {
274 	int err;
275 	struct cn_dev *dev = &cdev;
276 
277 	if (!cn_already_initialized)
278 		return -EAGAIN;
279 
280 	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
281 	if (err)
282 		return err;
283 
284 	cn_notify(id, 0);
285 
286 	return 0;
287 }
288 EXPORT_SYMBOL_GPL(cn_add_callback);
289 
290 /*
291  * Callback remove routing - removes callback
292  * with given ID.
293  * If there is no registered callback with given
294  * ID nothing happens.
295  *
296  * May sleep while waiting for reference counter to become zero.
297  */
298 void cn_del_callback(struct cb_id *id)
299 {
300 	struct cn_dev *dev = &cdev;
301 
302 	cn_queue_del_callback(dev->cbdev, id);
303 	cn_notify(id, 1);
304 }
305 EXPORT_SYMBOL_GPL(cn_del_callback);
306 
307 /*
308  * Checks two connector's control messages to be the same.
309  * Returns 1 if they are the same or if the first one is corrupted.
310  */
311 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
312 {
313 	int i;
314 	struct cn_notify_req *req1, *req2;
315 
316 	if (m1->idx_notify_num != m2->idx_notify_num)
317 		return 0;
318 
319 	if (m1->val_notify_num != m2->val_notify_num)
320 		return 0;
321 
322 	if (m1->len != m2->len)
323 		return 0;
324 
325 	if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
326 	    m1->len)
327 		return 1;
328 
329 	req1 = (struct cn_notify_req *)m1->data;
330 	req2 = (struct cn_notify_req *)m2->data;
331 
332 	for (i = 0; i < m1->idx_notify_num; ++i) {
333 		if (req1->first != req2->first || req1->range != req2->range)
334 			return 0;
335 		req1++;
336 		req2++;
337 	}
338 
339 	for (i = 0; i < m1->val_notify_num; ++i) {
340 		if (req1->first != req2->first || req1->range != req2->range)
341 			return 0;
342 		req1++;
343 		req2++;
344 	}
345 
346 	return 1;
347 }
348 
349 /*
350  * Main connector device's callback.
351  *
352  * Used for notification of a request's processing.
353  */
354 static void cn_callback(void *data)
355 {
356 	struct cn_msg *msg = data;
357 	struct cn_ctl_msg *ctl;
358 	struct cn_ctl_entry *ent;
359 	u32 size;
360 
361 	if (msg->len < sizeof(*ctl))
362 		return;
363 
364 	ctl = (struct cn_ctl_msg *)msg->data;
365 
366 	size = (sizeof(*ctl) + ((ctl->idx_notify_num +
367 				 ctl->val_notify_num) *
368 				sizeof(struct cn_notify_req)));
369 
370 	if (msg->len != size)
371 		return;
372 
373 	if (ctl->len + sizeof(*ctl) != msg->len)
374 		return;
375 
376 	/*
377 	 * Remove notification.
378 	 */
379 	if (ctl->group == 0) {
380 		struct cn_ctl_entry *n;
381 
382 		mutex_lock(&notify_lock);
383 		list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
384 			if (cn_ctl_msg_equals(ent->msg, ctl)) {
385 				list_del(&ent->notify_entry);
386 				kfree(ent);
387 			}
388 		}
389 		mutex_unlock(&notify_lock);
390 
391 		return;
392 	}
393 
394 	size += sizeof(*ent);
395 
396 	ent = kzalloc(size, GFP_KERNEL);
397 	if (!ent)
398 		return;
399 
400 	ent->msg = (struct cn_ctl_msg *)(ent + 1);
401 
402 	memcpy(ent->msg, ctl, size - sizeof(*ent));
403 
404 	mutex_lock(&notify_lock);
405 	list_add(&ent->notify_entry, &notify_list);
406 	mutex_unlock(&notify_lock);
407 }
408 
409 static int cn_proc_show(struct seq_file *m, void *v)
410 {
411 	struct cn_queue_dev *dev = cdev.cbdev;
412 	struct cn_callback_entry *cbq;
413 
414 	seq_printf(m, "Name            ID\n");
415 
416 	spin_lock_bh(&dev->queue_lock);
417 
418 	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
419 		seq_printf(m, "%-15s %u:%u\n",
420 			   cbq->id.name,
421 			   cbq->id.id.idx,
422 			   cbq->id.id.val);
423 	}
424 
425 	spin_unlock_bh(&dev->queue_lock);
426 
427 	return 0;
428 }
429 
430 static int cn_proc_open(struct inode *inode, struct file *file)
431 {
432 	return single_open(file, cn_proc_show, NULL);
433 }
434 
435 static const struct file_operations cn_file_ops = {
436 	.owner   = THIS_MODULE,
437 	.open    = cn_proc_open,
438 	.read    = seq_read,
439 	.llseek  = seq_lseek,
440 	.release = single_release
441 };
442 
443 static int __devinit cn_init(void)
444 {
445 	struct cn_dev *dev = &cdev;
446 	int err;
447 
448 	dev->input = cn_rx_skb;
449 	dev->id.idx = cn_idx;
450 	dev->id.val = cn_val;
451 
452 	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
453 					 CN_NETLINK_USERS + 0xf,
454 					 dev->input, NULL, THIS_MODULE);
455 	if (!dev->nls)
456 		return -EIO;
457 
458 	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
459 	if (!dev->cbdev) {
460 		netlink_kernel_release(dev->nls);
461 		return -EINVAL;
462 	}
463 
464 	cn_already_initialized = 1;
465 
466 	err = cn_add_callback(&dev->id, "connector", &cn_callback);
467 	if (err) {
468 		cn_already_initialized = 0;
469 		cn_queue_free_dev(dev->cbdev);
470 		netlink_kernel_release(dev->nls);
471 		return -EINVAL;
472 	}
473 
474 	proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
475 
476 	return 0;
477 }
478 
479 static void __devexit cn_fini(void)
480 {
481 	struct cn_dev *dev = &cdev;
482 
483 	cn_already_initialized = 0;
484 
485 	proc_net_remove(&init_net, "connector");
486 
487 	cn_del_callback(&dev->id);
488 	cn_queue_free_dev(dev->cbdev);
489 	netlink_kernel_release(dev->nls);
490 }
491 
492 subsys_initcall(cn_init);
493 module_exit(cn_fini);
494