net/caif/cfctrl.c

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