xref: /openbmc/linux/drivers/connector/connector.c (revision e8e0929d) 
1 /*
2  * 	connector.c
3  *
4  * 2004+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
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 <zbr@ioremap.net>");
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 sk_buff *skb)
133 {
134 	struct cn_callback_entry *__cbq, *__new_cbq;
135 	struct cn_dev *dev = &cdev;
136 	struct cn_msg *msg = NLMSG_DATA(nlmsg_hdr(skb));
137 	int err = -ENODEV;
138 
139 	spin_lock_bh(&dev->cbdev->queue_lock);
140 	list_for_each_entry(__cbq, &dev->cbdev->queue_list, callback_entry) {
141 		if (cn_cb_equal(&__cbq->id.id, &msg->id)) {
142 			if (likely(!work_pending(&__cbq->work) &&
143 					__cbq->data.skb == NULL)) {
144 				__cbq->data.skb = skb;
145 
146 				if (queue_cn_work(__cbq, &__cbq->work))
147 					err = 0;
148 				else
149 					err = -EINVAL;
150 			} else {
151 				struct cn_callback_data *d;
152 
153 				err = -ENOMEM;
154 				__new_cbq = kzalloc(sizeof(struct cn_callback_entry), GFP_ATOMIC);
155 				if (__new_cbq) {
156 					d = &__new_cbq->data;
157 					d->skb = skb;
158 					d->callback = __cbq->data.callback;
159 					d->free = __new_cbq;
160 
161 					__new_cbq->pdev = __cbq->pdev;
162 
163 					INIT_WORK(&__new_cbq->work,
164 							&cn_queue_wrapper);
165 
166 					if (queue_cn_work(__new_cbq,
167 						    &__new_cbq->work))
168 						err = 0;
169 					else {
170 						kfree(__new_cbq);
171 						err = -EINVAL;
172 					}
173 				}
174 			}
175 			break;
176 		}
177 	}
178 	spin_unlock_bh(&dev->cbdev->queue_lock);
179 
180 	return err;
181 }
182 
183 /*
184  * Main netlink receiving function.
185  *
186  * It checks skb, netlink header and msg sizes, and calls callback helper.
187  */
188 static void cn_rx_skb(struct sk_buff *__skb)
189 {
190 	struct nlmsghdr *nlh;
191 	int err;
192 	struct sk_buff *skb;
193 
194 	skb = skb_get(__skb);
195 
196 	if (skb->len >= NLMSG_SPACE(0)) {
197 		nlh = nlmsg_hdr(skb);
198 
199 		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
200 		    skb->len < nlh->nlmsg_len ||
201 		    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
202 			kfree_skb(skb);
203 			return;
204 		}
205 
206 		err = cn_call_callback(skb);
207 		if (err < 0)
208 			kfree_skb(skb);
209 	}
210 }
211 
212 /*
213  * Notification routing.
214  *
215  * Gets id and checks if there are notification request for it's idx
216  * and val.  If there are such requests notify the listeners with the
217  * given notify event.
218  *
219  */
220 static void cn_notify(struct cb_id *id, u32 notify_event)
221 {
222 	struct cn_ctl_entry *ent;
223 
224 	mutex_lock(&notify_lock);
225 	list_for_each_entry(ent, &notify_list, notify_entry) {
226 		int i;
227 		struct cn_notify_req *req;
228 		struct cn_ctl_msg *ctl = ent->msg;
229 		int idx_found, val_found;
230 
231 		idx_found = val_found = 0;
232 
233 		req = (struct cn_notify_req *)ctl->data;
234 		for (i = 0; i < ctl->idx_notify_num; ++i, ++req) {
235 			if (id->idx >= req->first &&
236 					id->idx < req->first + req->range) {
237 				idx_found = 1;
238 				break;
239 			}
240 		}
241 
242 		for (i = 0; i < ctl->val_notify_num; ++i, ++req) {
243 			if (id->val >= req->first &&
244 					id->val < req->first + req->range) {
245 				val_found = 1;
246 				break;
247 			}
248 		}
249 
250 		if (idx_found && val_found) {
251 			struct cn_msg m = { .ack = notify_event, };
252 
253 			memcpy(&m.id, id, sizeof(m.id));
254 			cn_netlink_send(&m, ctl->group, GFP_KERNEL);
255 		}
256 	}
257 	mutex_unlock(&notify_lock);
258 }
259 
260 /*
261  * Callback add routing - adds callback with given ID and name.
262  * If there is registered callback with the same ID it will not be added.
263  *
264  * May sleep.
265  */
266 int cn_add_callback(struct cb_id *id, char *name,
267 		    void (*callback)(struct cn_msg *, struct netlink_skb_parms *))
268 {
269 	int err;
270 	struct cn_dev *dev = &cdev;
271 
272 	if (!cn_already_initialized)
273 		return -EAGAIN;
274 
275 	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
276 	if (err)
277 		return err;
278 
279 	cn_notify(id, 0);
280 
281 	return 0;
282 }
283 EXPORT_SYMBOL_GPL(cn_add_callback);
284 
285 /*
286  * Callback remove routing - removes callback
287  * with given ID.
288  * If there is no registered callback with given
289  * ID nothing happens.
290  *
291  * May sleep while waiting for reference counter to become zero.
292  */
293 void cn_del_callback(struct cb_id *id)
294 {
295 	struct cn_dev *dev = &cdev;
296 
297 	cn_queue_del_callback(dev->cbdev, id);
298 	cn_notify(id, 1);
299 }
300 EXPORT_SYMBOL_GPL(cn_del_callback);
301 
302 /*
303  * Checks two connector's control messages to be the same.
304  * Returns 1 if they are the same or if the first one is corrupted.
305  */
306 static int cn_ctl_msg_equals(struct cn_ctl_msg *m1, struct cn_ctl_msg *m2)
307 {
308 	int i;
309 	struct cn_notify_req *req1, *req2;
310 
311 	if (m1->idx_notify_num != m2->idx_notify_num)
312 		return 0;
313 
314 	if (m1->val_notify_num != m2->val_notify_num)
315 		return 0;
316 
317 	if (m1->len != m2->len)
318 		return 0;
319 
320 	if ((m1->idx_notify_num + m1->val_notify_num) * sizeof(*req1) !=
321 	    m1->len)
322 		return 1;
323 
324 	req1 = (struct cn_notify_req *)m1->data;
325 	req2 = (struct cn_notify_req *)m2->data;
326 
327 	for (i = 0; i < m1->idx_notify_num; ++i) {
328 		if (req1->first != req2->first || req1->range != req2->range)
329 			return 0;
330 		req1++;
331 		req2++;
332 	}
333 
334 	for (i = 0; i < m1->val_notify_num; ++i) {
335 		if (req1->first != req2->first || req1->range != req2->range)
336 			return 0;
337 		req1++;
338 		req2++;
339 	}
340 
341 	return 1;
342 }
343 
344 /*
345  * Main connector device's callback.
346  *
347  * Used for notification of a request's processing.
348  */
349 static void cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
350 {
351 	struct cn_ctl_msg *ctl;
352 	struct cn_ctl_entry *ent;
353 	u32 size;
354 
355 	if (msg->len < sizeof(*ctl))
356 		return;
357 
358 	ctl = (struct cn_ctl_msg *)msg->data;
359 
360 	size = (sizeof(*ctl) + ((ctl->idx_notify_num +
361 				 ctl->val_notify_num) *
362 				sizeof(struct cn_notify_req)));
363 
364 	if (msg->len != size)
365 		return;
366 
367 	if (ctl->len + sizeof(*ctl) != msg->len)
368 		return;
369 
370 	/*
371 	 * Remove notification.
372 	 */
373 	if (ctl->group == 0) {
374 		struct cn_ctl_entry *n;
375 
376 		mutex_lock(&notify_lock);
377 		list_for_each_entry_safe(ent, n, &notify_list, notify_entry) {
378 			if (cn_ctl_msg_equals(ent->msg, ctl)) {
379 				list_del(&ent->notify_entry);
380 				kfree(ent);
381 			}
382 		}
383 		mutex_unlock(&notify_lock);
384 
385 		return;
386 	}
387 
388 	size += sizeof(*ent);
389 
390 	ent = kzalloc(size, GFP_KERNEL);
391 	if (!ent)
392 		return;
393 
394 	ent->msg = (struct cn_ctl_msg *)(ent + 1);
395 
396 	memcpy(ent->msg, ctl, size - sizeof(*ent));
397 
398 	mutex_lock(&notify_lock);
399 	list_add(&ent->notify_entry, &notify_list);
400 	mutex_unlock(&notify_lock);
401 }
402 
403 static int cn_proc_show(struct seq_file *m, void *v)
404 {
405 	struct cn_queue_dev *dev = cdev.cbdev;
406 	struct cn_callback_entry *cbq;
407 
408 	seq_printf(m, "Name            ID\n");
409 
410 	spin_lock_bh(&dev->queue_lock);
411 
412 	list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
413 		seq_printf(m, "%-15s %u:%u\n",
414 			   cbq->id.name,
415 			   cbq->id.id.idx,
416 			   cbq->id.id.val);
417 	}
418 
419 	spin_unlock_bh(&dev->queue_lock);
420 
421 	return 0;
422 }
423 
424 static int cn_proc_open(struct inode *inode, struct file *file)
425 {
426 	return single_open(file, cn_proc_show, NULL);
427 }
428 
429 static const struct file_operations cn_file_ops = {
430 	.owner   = THIS_MODULE,
431 	.open    = cn_proc_open,
432 	.read    = seq_read,
433 	.llseek  = seq_lseek,
434 	.release = single_release
435 };
436 
437 static int __devinit cn_init(void)
438 {
439 	struct cn_dev *dev = &cdev;
440 	int err;
441 
442 	dev->input = cn_rx_skb;
443 	dev->id.idx = cn_idx;
444 	dev->id.val = cn_val;
445 
446 	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR,
447 					 CN_NETLINK_USERS + 0xf,
448 					 dev->input, NULL, THIS_MODULE);
449 	if (!dev->nls)
450 		return -EIO;
451 
452 	dev->cbdev = cn_queue_alloc_dev("cqueue", dev->nls);
453 	if (!dev->cbdev) {
454 		netlink_kernel_release(dev->nls);
455 		return -EINVAL;
456 	}
457 
458 	cn_already_initialized = 1;
459 
460 	err = cn_add_callback(&dev->id, "connector", &cn_callback);
461 	if (err) {
462 		cn_already_initialized = 0;
463 		cn_queue_free_dev(dev->cbdev);
464 		netlink_kernel_release(dev->nls);
465 		return -EINVAL;
466 	}
467 
468 	proc_net_fops_create(&init_net, "connector", S_IRUGO, &cn_file_ops);
469 
470 	return 0;
471 }
472 
473 static void __devexit cn_fini(void)
474 {
475 	struct cn_dev *dev = &cdev;
476 
477 	cn_already_initialized = 0;
478 
479 	proc_net_remove(&init_net, "connector");
480 
481 	cn_del_callback(&dev->id);
482 	cn_queue_free_dev(dev->cbdev);
483 	netlink_kernel_release(dev->nls);
484 }
485 
486 subsys_initcall(cn_init);
487 module_exit(cn_fini);
488