xref: /openbmc/linux/net/caif/cfctrl.c (revision 4800cd83)
1 /*
2  * Copyright (C) ST-Ericsson AB 2010
3  * Author:	Sjur Brendeland/sjur.brandeland@stericsson.com
4  * License terms: GNU General Public License (GPL) version 2
5  */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
8 
9 #include <linux/stddef.h>
10 #include <linux/spinlock.h>
11 #include <linux/slab.h>
12 #include <net/caif/caif_layer.h>
13 #include <net/caif/cfpkt.h>
14 #include <net/caif/cfctrl.h>
15 
16 #define container_obj(layr) container_of(layr, struct cfctrl, serv.layer)
17 #define UTILITY_NAME_LENGTH 16
18 #define CFPKT_CTRL_PKT_LEN 20
19 
20 
21 #ifdef CAIF_NO_LOOP
22 static int handle_loop(struct cfctrl *ctrl,
23 			      int cmd, struct cfpkt *pkt){
24 	return -1;
25 }
26 #else
27 static int handle_loop(struct cfctrl *ctrl,
28 		int cmd, struct cfpkt *pkt);
29 #endif
30 static int cfctrl_recv(struct cflayer *layr, struct cfpkt *pkt);
31 static void cfctrl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
32 			   int phyid);
33 
34 
35 struct cflayer *cfctrl_create(void)
36 {
37 	struct dev_info dev_info;
38 	struct cfctrl *this =
39 		kmalloc(sizeof(struct cfctrl), GFP_ATOMIC);
40 	if (!this) {
41 		pr_warn("Out of memory\n");
42 		return NULL;
43 	}
44 	caif_assert(offsetof(struct cfctrl, serv.layer) == 0);
45 	memset(&dev_info, 0, sizeof(dev_info));
46 	dev_info.id = 0xff;
47 	memset(this, 0, sizeof(*this));
48 	cfsrvl_init(&this->serv, 0, &dev_info, false);
49 	atomic_set(&this->req_seq_no, 1);
50 	atomic_set(&this->rsp_seq_no, 1);
51 	this->serv.layer.receive = cfctrl_recv;
52 	sprintf(this->serv.layer.name, "ctrl");
53 	this->serv.layer.ctrlcmd = cfctrl_ctrlcmd;
54 	spin_lock_init(&this->loop_linkid_lock);
55 	spin_lock_init(&this->info_list_lock);
56 	INIT_LIST_HEAD(&this->list);
57 	this->loop_linkid = 1;
58 	return &this->serv.layer;
59 }
60 
61 static bool param_eq(struct cfctrl_link_param *p1, struct cfctrl_link_param *p2)
62 {
63 	bool eq =
64 	    p1->linktype == p2->linktype &&
65 	    p1->priority == p2->priority &&
66 	    p1->phyid == p2->phyid &&
67 	    p1->endpoint == p2->endpoint && p1->chtype == p2->chtype;
68 
69 	if (!eq)
70 		return false;
71 
72 	switch (p1->linktype) {
73 	case CFCTRL_SRV_VEI:
74 		return true;
75 	case CFCTRL_SRV_DATAGRAM:
76 		return p1->u.datagram.connid == p2->u.datagram.connid;
77 	case CFCTRL_SRV_RFM:
78 		return
79 		    p1->u.rfm.connid == p2->u.rfm.connid &&
80 		    strcmp(p1->u.rfm.volume, p2->u.rfm.volume) == 0;
81 	case CFCTRL_SRV_UTIL:
82 		return
83 		    p1->u.utility.fifosize_kb == p2->u.utility.fifosize_kb
84 		    && p1->u.utility.fifosize_bufs ==
85 		    p2->u.utility.fifosize_bufs
86 		    && strcmp(p1->u.utility.name, p2->u.utility.name) == 0
87 		    && p1->u.utility.paramlen == p2->u.utility.paramlen
88 		    && memcmp(p1->u.utility.params, p2->u.utility.params,
89 			      p1->u.utility.paramlen) == 0;
90 
91 	case CFCTRL_SRV_VIDEO:
92 		return p1->u.video.connid == p2->u.video.connid;
93 	case CFCTRL_SRV_DBG:
94 		return true;
95 	case CFCTRL_SRV_DECM:
96 		return false;
97 	default:
98 		return false;
99 	}
100 	return false;
101 }
102 
103 bool cfctrl_req_eq(struct cfctrl_request_info *r1,
104 		   struct cfctrl_request_info *r2)
105 {
106 	if (r1->cmd != r2->cmd)
107 		return false;
108 	if (r1->cmd == CFCTRL_CMD_LINK_SETUP)
109 		return param_eq(&r1->param, &r2->param);
110 	else
111 		return r1->channel_id == r2->channel_id;
112 }
113 
114 /* Insert request at the end */
115 void cfctrl_insert_req(struct cfctrl *ctrl,
116 			      struct cfctrl_request_info *req)
117 {
118 	spin_lock(&ctrl->info_list_lock);
119 	atomic_inc(&ctrl->req_seq_no);
120 	req->sequence_no = atomic_read(&ctrl->req_seq_no);
121 	list_add_tail(&req->list, &ctrl->list);
122 	spin_unlock(&ctrl->info_list_lock);
123 }
124 
125 /* Compare and remove request */
126 struct cfctrl_request_info *cfctrl_remove_req(struct cfctrl *ctrl,
127 					      struct cfctrl_request_info *req)
128 {
129 	struct cfctrl_request_info *p, *tmp, *first;
130 
131 	spin_lock(&ctrl->info_list_lock);
132 	first = list_first_entry(&ctrl->list, struct cfctrl_request_info, list);
133 
134 	list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
135 		if (cfctrl_req_eq(req, p)) {
136 			if (p != first)
137 				pr_warn("Requests are not received in order\n");
138 
139 			atomic_set(&ctrl->rsp_seq_no,
140 					 p->sequence_no);
141 			list_del(&p->list);
142 			goto out;
143 		}
144 	}
145 	p = NULL;
146 out:
147 	spin_unlock(&ctrl->info_list_lock);
148 	return p;
149 }
150 
151 struct cfctrl_rsp *cfctrl_get_respfuncs(struct cflayer *layer)
152 {
153 	struct cfctrl *this = container_obj(layer);
154 	return &this->res;
155 }
156 
157 void cfctrl_set_dnlayer(struct cflayer *this, struct cflayer *dn)
158 {
159 	this->dn = dn;
160 }
161 
162 void cfctrl_set_uplayer(struct cflayer *this, struct cflayer *up)
163 {
164 	this->up = up;
165 }
166 
167 static void init_info(struct caif_payload_info *info, struct cfctrl *cfctrl)
168 {
169 	info->hdr_len = 0;
170 	info->channel_id = cfctrl->serv.layer.id;
171 	info->dev_info = &cfctrl->serv.dev_info;
172 }
173 
174 void cfctrl_enum_req(struct cflayer *layer, u8 physlinkid)
175 {
176 	struct cfctrl *cfctrl = container_obj(layer);
177 	int ret;
178 	struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
179 	if (!pkt) {
180 		pr_warn("Out of memory\n");
181 		return;
182 	}
183 	caif_assert(offsetof(struct cfctrl, serv.layer) == 0);
184 	init_info(cfpkt_info(pkt), cfctrl);
185 	cfpkt_info(pkt)->dev_info->id = physlinkid;
186 	cfctrl->serv.dev_info.id = physlinkid;
187 	cfpkt_addbdy(pkt, CFCTRL_CMD_ENUM);
188 	cfpkt_addbdy(pkt, physlinkid);
189 	ret =
190 	    cfctrl->serv.layer.dn->transmit(cfctrl->serv.layer.dn, pkt);
191 	if (ret < 0) {
192 		pr_err("Could not transmit enum message\n");
193 		cfpkt_destroy(pkt);
194 	}
195 }
196 
197 int cfctrl_linkup_request(struct cflayer *layer,
198 			   struct cfctrl_link_param *param,
199 			   struct cflayer *user_layer)
200 {
201 	struct cfctrl *cfctrl = container_obj(layer);
202 	u32 tmp32;
203 	u16 tmp16;
204 	u8 tmp8;
205 	struct cfctrl_request_info *req;
206 	int ret;
207 	char utility_name[16];
208 	struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
209 	if (!pkt) {
210 		pr_warn("Out of memory\n");
211 		return -ENOMEM;
212 	}
213 	cfpkt_addbdy(pkt, CFCTRL_CMD_LINK_SETUP);
214 	cfpkt_addbdy(pkt, (param->chtype << 4) + param->linktype);
215 	cfpkt_addbdy(pkt, (param->priority << 3) + param->phyid);
216 	cfpkt_addbdy(pkt, param->endpoint & 0x03);
217 
218 	switch (param->linktype) {
219 	case CFCTRL_SRV_VEI:
220 		break;
221 	case CFCTRL_SRV_VIDEO:
222 		cfpkt_addbdy(pkt, (u8) param->u.video.connid);
223 		break;
224 	case CFCTRL_SRV_DBG:
225 		break;
226 	case CFCTRL_SRV_DATAGRAM:
227 		tmp32 = cpu_to_le32(param->u.datagram.connid);
228 		cfpkt_add_body(pkt, &tmp32, 4);
229 		break;
230 	case CFCTRL_SRV_RFM:
231 		/* Construct a frame, convert DatagramConnectionID to network
232 		 * format long and copy it out...
233 		 */
234 		tmp32 = cpu_to_le32(param->u.rfm.connid);
235 		cfpkt_add_body(pkt, &tmp32, 4);
236 		/* Add volume name, including zero termination... */
237 		cfpkt_add_body(pkt, param->u.rfm.volume,
238 			       strlen(param->u.rfm.volume) + 1);
239 		break;
240 	case CFCTRL_SRV_UTIL:
241 		tmp16 = cpu_to_le16(param->u.utility.fifosize_kb);
242 		cfpkt_add_body(pkt, &tmp16, 2);
243 		tmp16 = cpu_to_le16(param->u.utility.fifosize_bufs);
244 		cfpkt_add_body(pkt, &tmp16, 2);
245 		memset(utility_name, 0, sizeof(utility_name));
246 		strncpy(utility_name, param->u.utility.name,
247 			UTILITY_NAME_LENGTH - 1);
248 		cfpkt_add_body(pkt, utility_name, UTILITY_NAME_LENGTH);
249 		tmp8 = param->u.utility.paramlen;
250 		cfpkt_add_body(pkt, &tmp8, 1);
251 		cfpkt_add_body(pkt, param->u.utility.params,
252 			       param->u.utility.paramlen);
253 		break;
254 	default:
255 		pr_warn("Request setup of bad link type = %d\n",
256 			param->linktype);
257 		return -EINVAL;
258 	}
259 	req = kzalloc(sizeof(*req), GFP_KERNEL);
260 	if (!req) {
261 		pr_warn("Out of memory\n");
262 		return -ENOMEM;
263 	}
264 	req->client_layer = user_layer;
265 	req->cmd = CFCTRL_CMD_LINK_SETUP;
266 	req->param = *param;
267 	cfctrl_insert_req(cfctrl, req);
268 	init_info(cfpkt_info(pkt), cfctrl);
269 	/*
270 	 * NOTE:Always send linkup and linkdown request on the same
271 	 *	device as the payload. Otherwise old queued up payload
272 	 *	might arrive with the newly allocated channel ID.
273 	 */
274 	cfpkt_info(pkt)->dev_info->id = param->phyid;
275 	ret =
276 	    cfctrl->serv.layer.dn->transmit(cfctrl->serv.layer.dn, pkt);
277 	if (ret < 0) {
278 		pr_err("Could not transmit linksetup request\n");
279 		cfpkt_destroy(pkt);
280 		return -ENODEV;
281 	}
282 	return 0;
283 }
284 
285 int cfctrl_linkdown_req(struct cflayer *layer, u8 channelid,
286 				struct cflayer *client)
287 {
288 	int ret;
289 	struct cfctrl *cfctrl = container_obj(layer);
290 	struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
291 	if (!pkt) {
292 		pr_warn("Out of memory\n");
293 		return -ENOMEM;
294 	}
295 	cfpkt_addbdy(pkt, CFCTRL_CMD_LINK_DESTROY);
296 	cfpkt_addbdy(pkt, channelid);
297 	init_info(cfpkt_info(pkt), cfctrl);
298 	ret =
299 	    cfctrl->serv.layer.dn->transmit(cfctrl->serv.layer.dn, pkt);
300 	if (ret < 0) {
301 		pr_err("Could not transmit link-down request\n");
302 		cfpkt_destroy(pkt);
303 	}
304 	return ret;
305 }
306 
307 void cfctrl_sleep_req(struct cflayer *layer)
308 {
309 	int ret;
310 	struct cfctrl *cfctrl = container_obj(layer);
311 	struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
312 	if (!pkt) {
313 		pr_warn("Out of memory\n");
314 		return;
315 	}
316 	cfpkt_addbdy(pkt, CFCTRL_CMD_SLEEP);
317 	init_info(cfpkt_info(pkt), cfctrl);
318 	ret =
319 	    cfctrl->serv.layer.dn->transmit(cfctrl->serv.layer.dn, pkt);
320 	if (ret < 0)
321 		cfpkt_destroy(pkt);
322 }
323 
324 void cfctrl_wake_req(struct cflayer *layer)
325 {
326 	int ret;
327 	struct cfctrl *cfctrl = container_obj(layer);
328 	struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
329 	if (!pkt) {
330 		pr_warn("Out of memory\n");
331 		return;
332 	}
333 	cfpkt_addbdy(pkt, CFCTRL_CMD_WAKE);
334 	init_info(cfpkt_info(pkt), cfctrl);
335 	ret =
336 	    cfctrl->serv.layer.dn->transmit(cfctrl->serv.layer.dn, pkt);
337 	if (ret < 0)
338 		cfpkt_destroy(pkt);
339 }
340 
341 void cfctrl_getstartreason_req(struct cflayer *layer)
342 {
343 	int ret;
344 	struct cfctrl *cfctrl = container_obj(layer);
345 	struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
346 	if (!pkt) {
347 		pr_warn("Out of memory\n");
348 		return;
349 	}
350 	cfpkt_addbdy(pkt, CFCTRL_CMD_START_REASON);
351 	init_info(cfpkt_info(pkt), cfctrl);
352 	ret =
353 	    cfctrl->serv.layer.dn->transmit(cfctrl->serv.layer.dn, pkt);
354 	if (ret < 0)
355 		cfpkt_destroy(pkt);
356 }
357 
358 
359 void cfctrl_cancel_req(struct cflayer *layr, struct cflayer *adap_layer)
360 {
361 	struct cfctrl_request_info *p, *tmp;
362 	struct cfctrl *ctrl = container_obj(layr);
363 	spin_lock(&ctrl->info_list_lock);
364 
365 	list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
366 		if (p->client_layer == adap_layer) {
367 			pr_debug("cancel req :%d\n", p->sequence_no);
368 			list_del(&p->list);
369 			kfree(p);
370 		}
371 	}
372 
373 	spin_unlock(&ctrl->info_list_lock);
374 }
375 
376 static int cfctrl_recv(struct cflayer *layer, struct cfpkt *pkt)
377 {
378 	u8 cmdrsp;
379 	u8 cmd;
380 	int ret = -1;
381 	u16 tmp16;
382 	u8 len;
383 	u8 param[255];
384 	u8 linkid;
385 	struct cfctrl *cfctrl = container_obj(layer);
386 	struct cfctrl_request_info rsp, *req;
387 
388 
389 	cfpkt_extr_head(pkt, &cmdrsp, 1);
390 	cmd = cmdrsp & CFCTRL_CMD_MASK;
391 	if (cmd != CFCTRL_CMD_LINK_ERR
392 	    && CFCTRL_RSP_BIT != (CFCTRL_RSP_BIT & cmdrsp)) {
393 		if (handle_loop(cfctrl, cmd, pkt) != 0)
394 			cmdrsp |= CFCTRL_ERR_BIT;
395 	}
396 
397 	switch (cmd) {
398 	case CFCTRL_CMD_LINK_SETUP:
399 		{
400 			enum cfctrl_srv serv;
401 			enum cfctrl_srv servtype;
402 			u8 endpoint;
403 			u8 physlinkid;
404 			u8 prio;
405 			u8 tmp;
406 			u32 tmp32;
407 			u8 *cp;
408 			int i;
409 			struct cfctrl_link_param linkparam;
410 			memset(&linkparam, 0, sizeof(linkparam));
411 
412 			cfpkt_extr_head(pkt, &tmp, 1);
413 
414 			serv = tmp & CFCTRL_SRV_MASK;
415 			linkparam.linktype = serv;
416 
417 			servtype = tmp >> 4;
418 			linkparam.chtype = servtype;
419 
420 			cfpkt_extr_head(pkt, &tmp, 1);
421 			physlinkid = tmp & 0x07;
422 			prio = tmp >> 3;
423 
424 			linkparam.priority = prio;
425 			linkparam.phyid = physlinkid;
426 			cfpkt_extr_head(pkt, &endpoint, 1);
427 			linkparam.endpoint = endpoint & 0x03;
428 
429 			switch (serv) {
430 			case CFCTRL_SRV_VEI:
431 			case CFCTRL_SRV_DBG:
432 				if (CFCTRL_ERR_BIT & cmdrsp)
433 					break;
434 				/* Link ID */
435 				cfpkt_extr_head(pkt, &linkid, 1);
436 				break;
437 			case CFCTRL_SRV_VIDEO:
438 				cfpkt_extr_head(pkt, &tmp, 1);
439 				linkparam.u.video.connid = tmp;
440 				if (CFCTRL_ERR_BIT & cmdrsp)
441 					break;
442 				/* Link ID */
443 				cfpkt_extr_head(pkt, &linkid, 1);
444 				break;
445 
446 			case CFCTRL_SRV_DATAGRAM:
447 				cfpkt_extr_head(pkt, &tmp32, 4);
448 				linkparam.u.datagram.connid =
449 				    le32_to_cpu(tmp32);
450 				if (CFCTRL_ERR_BIT & cmdrsp)
451 					break;
452 				/* Link ID */
453 				cfpkt_extr_head(pkt, &linkid, 1);
454 				break;
455 			case CFCTRL_SRV_RFM:
456 				/* Construct a frame, convert
457 				 * DatagramConnectionID
458 				 * to network format long and copy it out...
459 				 */
460 				cfpkt_extr_head(pkt, &tmp32, 4);
461 				linkparam.u.rfm.connid =
462 				  le32_to_cpu(tmp32);
463 				cp = (u8 *) linkparam.u.rfm.volume;
464 				for (cfpkt_extr_head(pkt, &tmp, 1);
465 				     cfpkt_more(pkt) && tmp != '\0';
466 				     cfpkt_extr_head(pkt, &tmp, 1))
467 					*cp++ = tmp;
468 				*cp = '\0';
469 
470 				if (CFCTRL_ERR_BIT & cmdrsp)
471 					break;
472 				/* Link ID */
473 				cfpkt_extr_head(pkt, &linkid, 1);
474 
475 				break;
476 			case CFCTRL_SRV_UTIL:
477 				/* Construct a frame, convert
478 				 * DatagramConnectionID
479 				 * to network format long and copy it out...
480 				 */
481 				/* Fifosize KB */
482 				cfpkt_extr_head(pkt, &tmp16, 2);
483 				linkparam.u.utility.fifosize_kb =
484 				    le16_to_cpu(tmp16);
485 				/* Fifosize bufs */
486 				cfpkt_extr_head(pkt, &tmp16, 2);
487 				linkparam.u.utility.fifosize_bufs =
488 				    le16_to_cpu(tmp16);
489 				/* name */
490 				cp = (u8 *) linkparam.u.utility.name;
491 				caif_assert(sizeof(linkparam.u.utility.name)
492 					     >= UTILITY_NAME_LENGTH);
493 				for (i = 0;
494 				     i < UTILITY_NAME_LENGTH
495 				     && cfpkt_more(pkt); i++) {
496 					cfpkt_extr_head(pkt, &tmp, 1);
497 					*cp++ = tmp;
498 				}
499 				/* Length */
500 				cfpkt_extr_head(pkt, &len, 1);
501 				linkparam.u.utility.paramlen = len;
502 				/* Param Data */
503 				cp = linkparam.u.utility.params;
504 				while (cfpkt_more(pkt) && len--) {
505 					cfpkt_extr_head(pkt, &tmp, 1);
506 					*cp++ = tmp;
507 				}
508 				if (CFCTRL_ERR_BIT & cmdrsp)
509 					break;
510 				/* Link ID */
511 				cfpkt_extr_head(pkt, &linkid, 1);
512 				/* Length */
513 				cfpkt_extr_head(pkt, &len, 1);
514 				/* Param Data */
515 				cfpkt_extr_head(pkt, &param, len);
516 				break;
517 			default:
518 				pr_warn("Request setup - invalid link type (%d)\n",
519 					serv);
520 				goto error;
521 			}
522 
523 			rsp.cmd = cmd;
524 			rsp.param = linkparam;
525 			req = cfctrl_remove_req(cfctrl, &rsp);
526 
527 			if (CFCTRL_ERR_BIT == (CFCTRL_ERR_BIT & cmdrsp) ||
528 				cfpkt_erroneous(pkt)) {
529 				pr_err("Invalid O/E bit or parse error on CAIF control channel\n");
530 				cfctrl->res.reject_rsp(cfctrl->serv.layer.up,
531 						       0,
532 						       req ? req->client_layer
533 						       : NULL);
534 			} else {
535 				cfctrl->res.linksetup_rsp(cfctrl->serv.
536 							  layer.up, linkid,
537 							  serv, physlinkid,
538 							  req ? req->
539 							  client_layer : NULL);
540 			}
541 
542 			if (req != NULL)
543 				kfree(req);
544 		}
545 		break;
546 	case CFCTRL_CMD_LINK_DESTROY:
547 		cfpkt_extr_head(pkt, &linkid, 1);
548 		cfctrl->res.linkdestroy_rsp(cfctrl->serv.layer.up, linkid);
549 		break;
550 	case CFCTRL_CMD_LINK_ERR:
551 		pr_err("Frame Error Indication received\n");
552 		cfctrl->res.linkerror_ind();
553 		break;
554 	case CFCTRL_CMD_ENUM:
555 		cfctrl->res.enum_rsp();
556 		break;
557 	case CFCTRL_CMD_SLEEP:
558 		cfctrl->res.sleep_rsp();
559 		break;
560 	case CFCTRL_CMD_WAKE:
561 		cfctrl->res.wake_rsp();
562 		break;
563 	case CFCTRL_CMD_LINK_RECONF:
564 		cfctrl->res.restart_rsp();
565 		break;
566 	case CFCTRL_CMD_RADIO_SET:
567 		cfctrl->res.radioset_rsp();
568 		break;
569 	default:
570 		pr_err("Unrecognized Control Frame\n");
571 		goto error;
572 		break;
573 	}
574 	ret = 0;
575 error:
576 	cfpkt_destroy(pkt);
577 	return ret;
578 }
579 
580 static void cfctrl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
581 			int phyid)
582 {
583 	struct cfctrl *this = container_obj(layr);
584 	switch (ctrl) {
585 	case _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND:
586 	case CAIF_CTRLCMD_FLOW_OFF_IND:
587 		spin_lock(&this->info_list_lock);
588 		if (!list_empty(&this->list)) {
589 			pr_debug("Received flow off in control layer\n");
590 		}
591 		spin_unlock(&this->info_list_lock);
592 		break;
593 	default:
594 		break;
595 	}
596 }
597 
598 #ifndef CAIF_NO_LOOP
599 static int handle_loop(struct cfctrl *ctrl, int cmd, struct cfpkt *pkt)
600 {
601 	static int last_linkid;
602 	u8 linkid, linktype, tmp;
603 	switch (cmd) {
604 	case CFCTRL_CMD_LINK_SETUP:
605 		spin_lock(&ctrl->loop_linkid_lock);
606 		for (linkid = last_linkid + 1; linkid < 255; linkid++)
607 			if (!ctrl->loop_linkused[linkid])
608 				goto found;
609 		for (linkid = last_linkid - 1; linkid > 0; linkid--)
610 			if (!ctrl->loop_linkused[linkid])
611 				goto found;
612 		spin_unlock(&ctrl->loop_linkid_lock);
613 		pr_err("Out of link-ids\n");
614 		return -EINVAL;
615 found:
616 		if (!ctrl->loop_linkused[linkid])
617 			ctrl->loop_linkused[linkid] = 1;
618 
619 		last_linkid = linkid;
620 
621 		cfpkt_add_trail(pkt, &linkid, 1);
622 		spin_unlock(&ctrl->loop_linkid_lock);
623 		cfpkt_peek_head(pkt, &linktype, 1);
624 		if (linktype ==  CFCTRL_SRV_UTIL) {
625 			tmp = 0x01;
626 			cfpkt_add_trail(pkt, &tmp, 1);
627 			cfpkt_add_trail(pkt, &tmp, 1);
628 		}
629 		break;
630 
631 	case CFCTRL_CMD_LINK_DESTROY:
632 		spin_lock(&ctrl->loop_linkid_lock);
633 		cfpkt_peek_head(pkt, &linkid, 1);
634 		ctrl->loop_linkused[linkid] = 0;
635 		spin_unlock(&ctrl->loop_linkid_lock);
636 		break;
637 	default:
638 		break;
639 	}
640 	return 0;
641 }
642 #endif
643