net/caif/cfctrl.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) ST-Ericsson AB 2010
   4  * Author:      Sjur Brendeland
   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 <linux/pkt_sched.h>
  13 #include <net/caif/caif_layer.h>
  14 #include <net/caif/cfpkt.h>
  15 #include <net/caif/cfctrl.h>
  16
  17 #define container_obj(layr) container_of(layr, struct cfctrl, serv.layer)
  18 #define UTILITY_NAME_LENGTH 16
  19 #define CFPKT_CTRL_PKT_LEN 20
  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                 kzalloc(sizeof(struct cfctrl), GFP_ATOMIC);
  40         if (!this)
  41                 return NULL;
  42         caif_assert(offsetof(struct cfctrl, serv.layer) == 0);
  43         memset(&dev_info, 0, sizeof(dev_info));
  44         dev_info.id = 0xff;
  45         cfsrvl_init(&this->serv, 0, &dev_info, false);
  46         atomic_set(&this->req_seq_no, 1);
  47         atomic_set(&this->rsp_seq_no, 1);
  48         this->serv.layer.receive = cfctrl_recv;
  49         sprintf(this->serv.layer.name, "ctrl");
  50         this->serv.layer.ctrlcmd = cfctrl_ctrlcmd;
  51 #ifndef CAIF_NO_LOOP
  52         spin_lock_init(&this->loop_linkid_lock);
  53         this->loop_linkid = 1;
  54 #endif
  55         spin_lock_init(&this->info_list_lock);
  56         INIT_LIST_HEAD(&this->list);
  57         return &this->serv.layer;
  58 }
  59
  60 void cfctrl_remove(struct cflayer *layer)
  61 {
  62         struct cfctrl_request_info *p, *tmp;
  63         struct cfctrl *ctrl = container_obj(layer);
  64
  65         spin_lock_bh(&ctrl->info_list_lock);
  66         list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
  67                 list_del(&p->list);
  68                 kfree(p);
  69         }
  70         spin_unlock_bh(&ctrl->info_list_lock);
  71         kfree(layer);
  72 }
  73
  74 static bool param_eq(const struct cfctrl_link_param *p1,
  75                      const struct cfctrl_link_param *p2)
  76 {
  77         bool eq =
  78             p1->linktype == p2->linktype &&
  79             p1->priority == p2->priority &&
  80             p1->phyid == p2->phyid &&
  81             p1->endpoint == p2->endpoint && p1->chtype == p2->chtype;
  82
  83         if (!eq)
  84                 return false;
  85
  86         switch (p1->linktype) {
  87         case CFCTRL_SRV_VEI:
  88                 return true;
  89         case CFCTRL_SRV_DATAGRAM:
  90                 return p1->u.datagram.connid == p2->u.datagram.connid;
  91         case CFCTRL_SRV_RFM:
  92                 return
  93                     p1->u.rfm.connid == p2->u.rfm.connid &&
  94                     strcmp(p1->u.rfm.volume, p2->u.rfm.volume) == 0;
  95         case CFCTRL_SRV_UTIL:
  96                 return
  97                     p1->u.utility.fifosize_kb == p2->u.utility.fifosize_kb
  98                     && p1->u.utility.fifosize_bufs ==
  99                     p2->u.utility.fifosize_bufs
 100                     && strcmp(p1->u.utility.name, p2->u.utility.name) == 0
 101                     && p1->u.utility.paramlen == p2->u.utility.paramlen
 102                     && memcmp(p1->u.utility.params, p2->u.utility.params,
 103                               p1->u.utility.paramlen) == 0;
 104
 105         case CFCTRL_SRV_VIDEO:
 106                 return p1->u.video.connid == p2->u.video.connid;
 107         case CFCTRL_SRV_DBG:
 108                 return true;
 109         case CFCTRL_SRV_DECM:
 110                 return false;
 111         default:
 112                 return false;
 113         }
 114         return false;
 115 }
 116
 117 static bool cfctrl_req_eq(const struct cfctrl_request_info *r1,
 118                           const struct cfctrl_request_info *r2)
 119 {
 120         if (r1->cmd != r2->cmd)
 121                 return false;
 122         if (r1->cmd == CFCTRL_CMD_LINK_SETUP)
 123                 return param_eq(&r1->param, &r2->param);
 124         else
 125                 return r1->channel_id == r2->channel_id;
 126 }
 127
 128 /* Insert request at the end */
 129 static void cfctrl_insert_req(struct cfctrl *ctrl,
 130                               struct cfctrl_request_info *req)
 131 {
 132         spin_lock_bh(&ctrl->info_list_lock);
 133         atomic_inc(&ctrl->req_seq_no);
 134         req->sequence_no = atomic_read(&ctrl->req_seq_no);
 135         list_add_tail(&req->list, &ctrl->list);
 136         spin_unlock_bh(&ctrl->info_list_lock);
 137 }
 138
 139 /* Compare and remove request */
 140 static struct cfctrl_request_info *cfctrl_remove_req(struct cfctrl *ctrl,
 141                                                 struct cfctrl_request_info *req)
 142 {
 143         struct cfctrl_request_info *p, *tmp, *first;
 144
 145         first = list_first_entry(&ctrl->list, struct cfctrl_request_info, list);
 146
 147         list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
 148                 if (cfctrl_req_eq(req, p)) {
 149                         if (p != first)
 150                                 pr_warn("Requests are not received in order\n");
 151
 152                         atomic_set(&ctrl->rsp_seq_no,
 153                                          p->sequence_no);
 154                         list_del(&p->list);
 155                         goto out;
 156                 }
 157         }
 158         p = NULL;
 159 out:
 160         return p;
 161 }
 162
 163 struct cfctrl_rsp *cfctrl_get_respfuncs(struct cflayer *layer)
 164 {
 165         struct cfctrl *this = container_obj(layer);
 166         return &this->res;
 167 }
 168
 169 static void init_info(struct caif_payload_info *info, struct cfctrl *cfctrl)
 170 {
 171         info->hdr_len = 0;
 172         info->channel_id = cfctrl->serv.layer.id;
 173         info->dev_info = &cfctrl->serv.dev_info;
 174 }
 175
 176 void cfctrl_enum_req(struct cflayer *layer, u8 physlinkid)
 177 {
 178         struct cfpkt *pkt;
 179         struct cfctrl *cfctrl = container_obj(layer);
 180         struct cflayer *dn = cfctrl->serv.layer.dn;
 181
 182         if (!dn) {
 183                 pr_debug("not able to send enum request\n");
 184                 return;
 185         }
 186         pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
 187         if (!pkt)
 188                 return;
 189         caif_assert(offsetof(struct cfctrl, serv.layer) == 0);
 190         init_info(cfpkt_info(pkt), cfctrl);
 191         cfpkt_info(pkt)->dev_info->id = physlinkid;
 192         cfctrl->serv.dev_info.id = physlinkid;
 193         cfpkt_addbdy(pkt, CFCTRL_CMD_ENUM);
 194         cfpkt_addbdy(pkt, physlinkid);
 195         cfpkt_set_prio(pkt, TC_PRIO_CONTROL);
 196         dn->transmit(dn, pkt);
 197 }
 198
 199 int cfctrl_linkup_request(struct cflayer *layer,
 200                           struct cfctrl_link_param *param,
 201                           struct cflayer *user_layer)
 202 {
 203         struct cfctrl *cfctrl = container_obj(layer);
 204         struct cflayer *dn = cfctrl->serv.layer.dn;
 205         char utility_name[UTILITY_NAME_LENGTH];
 206         struct cfctrl_request_info *req;
 207         struct cfpkt *pkt;
 208         u32 tmp32;
 209         u16 tmp16;
 210         u8 tmp8;
 211         int ret;
 212
 213         if (!dn) {
 214                 pr_debug("not able to send linkup request\n");
 215                 return -ENODEV;
 216         }
 217
 218         if (cfctrl_cancel_req(layer, user_layer) > 0) {
 219                 /* Slight Paranoia, check if already connecting */
 220                 pr_err("Duplicate connect request for same client\n");
 221                 WARN_ON(1);
 222                 return -EALREADY;
 223         }
 224
 225         pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
 226         if (!pkt)
 227                 return -ENOMEM;
 228         cfpkt_addbdy(pkt, CFCTRL_CMD_LINK_SETUP);
 229         cfpkt_addbdy(pkt, (param->chtype << 4) | param->linktype);
 230         cfpkt_addbdy(pkt, (param->priority << 3) | param->phyid);
 231         cfpkt_addbdy(pkt, param->endpoint & 0x03);
 232
 233         switch (param->linktype) {
 234         case CFCTRL_SRV_VEI:
 235                 break;
 236         case CFCTRL_SRV_VIDEO:
 237                 cfpkt_addbdy(pkt, (u8) param->u.video.connid);
 238                 break;
 239         case CFCTRL_SRV_DBG:
 240                 break;
 241         case CFCTRL_SRV_DATAGRAM:
 242                 tmp32 = cpu_to_le32(param->u.datagram.connid);
 243                 cfpkt_add_body(pkt, &tmp32, 4);
 244                 break;
 245         case CFCTRL_SRV_RFM:
 246                 /* Construct a frame, convert DatagramConnectionID to network
 247                  * format long and copy it out...
 248                  */
 249                 tmp32 = cpu_to_le32(param->u.rfm.connid);
 250                 cfpkt_add_body(pkt, &tmp32, 4);
 251                 /* Add volume name, including zero termination... */
 252                 cfpkt_add_body(pkt, param->u.rfm.volume,
 253                                strlen(param->u.rfm.volume) + 1);
 254                 break;
 255         case CFCTRL_SRV_UTIL:
 256                 tmp16 = cpu_to_le16(param->u.utility.fifosize_kb);
 257                 cfpkt_add_body(pkt, &tmp16, 2);
 258                 tmp16 = cpu_to_le16(param->u.utility.fifosize_bufs);
 259                 cfpkt_add_body(pkt, &tmp16, 2);
 260                 memset(utility_name, 0, sizeof(utility_name));
 261                 strscpy(utility_name, param->u.utility.name,
 262                         UTILITY_NAME_LENGTH);
 263                 cfpkt_add_body(pkt, utility_name, UTILITY_NAME_LENGTH);
 264                 tmp8 = param->u.utility.paramlen;
 265                 cfpkt_add_body(pkt, &tmp8, 1);
 266                 cfpkt_add_body(pkt, param->u.utility.params,
 267                                param->u.utility.paramlen);
 268                 break;
 269         default:
 270                 pr_warn("Request setup of bad link type = %d\n",
 271                         param->linktype);
 272                 cfpkt_destroy(pkt);
 273                 return -EINVAL;
 274         }
 275         req = kzalloc(sizeof(*req), GFP_KERNEL);
 276         if (!req) {
 277                 cfpkt_destroy(pkt);
 278                 return -ENOMEM;
 279         }
 280
 281         req->client_layer = user_layer;
 282         req->cmd = CFCTRL_CMD_LINK_SETUP;
 283         req->param = *param;
 284         cfctrl_insert_req(cfctrl, req);
 285         init_info(cfpkt_info(pkt), cfctrl);
 286         /*
 287          * NOTE:Always send linkup and linkdown request on the same
 288          *      device as the payload. Otherwise old queued up payload
 289          *      might arrive with the newly allocated channel ID.
 290          */
 291         cfpkt_info(pkt)->dev_info->id = param->phyid;
 292         cfpkt_set_prio(pkt, TC_PRIO_CONTROL);
 293         ret =
 294             dn->transmit(dn, pkt);
 295         if (ret < 0) {
 296                 int count;
 297
 298                 count = cfctrl_cancel_req(&cfctrl->serv.layer,
 299                                                 user_layer);
 300                 if (count != 1) {
 301                         pr_err("Could not remove request (%d)", count);
 302                         return -ENODEV;
 303                 }
 304         }
 305         return 0;
 306 }
 307
 308 int cfctrl_linkdown_req(struct cflayer *layer, u8 channelid,
 309                         struct cflayer *client)
 310 {
 311         int ret;
 312         struct cfpkt *pkt;
 313         struct cfctrl *cfctrl = container_obj(layer);
 314         struct cflayer *dn = cfctrl->serv.layer.dn;
 315
 316         if (!dn) {
 317                 pr_debug("not able to send link-down request\n");
 318                 return -ENODEV;
 319         }
 320         pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
 321         if (!pkt)
 322                 return -ENOMEM;
 323         cfpkt_addbdy(pkt, CFCTRL_CMD_LINK_DESTROY);
 324         cfpkt_addbdy(pkt, channelid);
 325         init_info(cfpkt_info(pkt), cfctrl);
 326         cfpkt_set_prio(pkt, TC_PRIO_CONTROL);
 327         ret =
 328             dn->transmit(dn, pkt);
 329 #ifndef CAIF_NO_LOOP
 330         cfctrl->loop_linkused[channelid] = 0;
 331 #endif
 332         return ret;
 333 }
 334
 335 int cfctrl_cancel_req(struct cflayer *layr, struct cflayer *adap_layer)
 336 {
 337         struct cfctrl_request_info *p, *tmp;
 338         struct cfctrl *ctrl = container_obj(layr);
 339         int found = 0;
 340         spin_lock_bh(&ctrl->info_list_lock);
 341
 342         list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
 343                 if (p->client_layer == adap_layer) {
 344                         list_del(&p->list);
 345                         kfree(p);
 346                         found++;
 347                 }
 348         }
 349
 350         spin_unlock_bh(&ctrl->info_list_lock);
 351         return found;
 352 }
 353
 354 static int cfctrl_recv(struct cflayer *layer, struct cfpkt *pkt)
 355 {
 356         u8 cmdrsp;
 357         u8 cmd;
 358         int ret = -1;
 359         u8 len;
 360         u8 param[255];
 361         u8 linkid = 0;
 362         struct cfctrl *cfctrl = container_obj(layer);
 363         struct cfctrl_request_info rsp, *req;
 364
 365
 366         cmdrsp = cfpkt_extr_head_u8(pkt);
 367         cmd = cmdrsp & CFCTRL_CMD_MASK;
 368         if (cmd != CFCTRL_CMD_LINK_ERR
 369             && CFCTRL_RSP_BIT != (CFCTRL_RSP_BIT & cmdrsp)
 370                 && CFCTRL_ERR_BIT != (CFCTRL_ERR_BIT & cmdrsp)) {
 371                 if (handle_loop(cfctrl, cmd, pkt) != 0)
 372                         cmdrsp |= CFCTRL_ERR_BIT;
 373         }
 374
 375         switch (cmd) {
 376         case CFCTRL_CMD_LINK_SETUP:
 377                 {
 378                         enum cfctrl_srv serv;
 379                         enum cfctrl_srv servtype;
 380                         u8 endpoint;
 381                         u8 physlinkid;
 382                         u8 prio;
 383                         u8 tmp;
 384                         u8 *cp;
 385                         int i;
 386                         struct cfctrl_link_param linkparam;
 387                         memset(&linkparam, 0, sizeof(linkparam));
 388
 389                         tmp = cfpkt_extr_head_u8(pkt);
 390
 391                         serv = tmp & CFCTRL_SRV_MASK;
 392                         linkparam.linktype = serv;
 393
 394                         servtype = tmp >> 4;
 395                         linkparam.chtype = servtype;
 396
 397                         tmp = cfpkt_extr_head_u8(pkt);
 398                         physlinkid = tmp & 0x07;
 399                         prio = tmp >> 3;
 400
 401                         linkparam.priority = prio;
 402                         linkparam.phyid = physlinkid;
 403                         endpoint = cfpkt_extr_head_u8(pkt);
 404                         linkparam.endpoint = endpoint & 0x03;
 405
 406                         switch (serv) {
 407                         case CFCTRL_SRV_VEI:
 408                         case CFCTRL_SRV_DBG:
 409                                 if (CFCTRL_ERR_BIT & cmdrsp)
 410                                         break;
 411                                 /* Link ID */
 412                                 linkid = cfpkt_extr_head_u8(pkt);
 413                                 break;
 414                         case CFCTRL_SRV_VIDEO:
 415                                 tmp = cfpkt_extr_head_u8(pkt);
 416                                 linkparam.u.video.connid = tmp;
 417                                 if (CFCTRL_ERR_BIT & cmdrsp)
 418                                         break;
 419                                 /* Link ID */
 420                                 linkid = cfpkt_extr_head_u8(pkt);
 421                                 break;
 422
 423                         case CFCTRL_SRV_DATAGRAM:
 424                                 linkparam.u.datagram.connid =
 425                                     cfpkt_extr_head_u32(pkt);
 426                                 if (CFCTRL_ERR_BIT & cmdrsp)
 427                                         break;
 428                                 /* Link ID */
 429                                 linkid = cfpkt_extr_head_u8(pkt);
 430                                 break;
 431                         case CFCTRL_SRV_RFM:
 432                                 /* Construct a frame, convert
 433                                  * DatagramConnectionID
 434                                  * to network format long and copy it out...
 435                                  */
 436                                 linkparam.u.rfm.connid =
 437                                     cfpkt_extr_head_u32(pkt);
 438                                 cp = (u8 *) linkparam.u.rfm.volume;
 439                                 for (tmp = cfpkt_extr_head_u8(pkt);
 440                                      cfpkt_more(pkt) && tmp != '\0';
 441                                      tmp = cfpkt_extr_head_u8(pkt))
 442                                         *cp++ = tmp;
 443                                 *cp = '\0';
 444
 445                                 if (CFCTRL_ERR_BIT & cmdrsp)
 446                                         break;
 447                                 /* Link ID */
 448                                 linkid = cfpkt_extr_head_u8(pkt);
 449
 450                                 break;
 451                         case CFCTRL_SRV_UTIL:
 452                                 /* Construct a frame, convert
 453                                  * DatagramConnectionID
 454                                  * to network format long and copy it out...
 455                                  */
 456                                 /* Fifosize KB */
 457                                 linkparam.u.utility.fifosize_kb =
 458                                     cfpkt_extr_head_u16(pkt);
 459                                 /* Fifosize bufs */
 460                                 linkparam.u.utility.fifosize_bufs =
 461                                     cfpkt_extr_head_u16(pkt);
 462                                 /* name */
 463                                 cp = (u8 *) linkparam.u.utility.name;
 464                                 caif_assert(sizeof(linkparam.u.utility.name)
 465                                              >= UTILITY_NAME_LENGTH);
 466                                 for (i = 0;
 467                                      i < UTILITY_NAME_LENGTH
 468                                      && cfpkt_more(pkt); i++) {
 469                                         tmp = cfpkt_extr_head_u8(pkt);
 470                                         *cp++ = tmp;
 471                                 }
 472                                 /* Length */
 473                                 len = cfpkt_extr_head_u8(pkt);
 474                                 linkparam.u.utility.paramlen = len;
 475                                 /* Param Data */
 476                                 cp = linkparam.u.utility.params;
 477                                 while (cfpkt_more(pkt) && len--) {
 478                                         tmp = cfpkt_extr_head_u8(pkt);
 479                                         *cp++ = tmp;
 480                                 }
 481                                 if (CFCTRL_ERR_BIT & cmdrsp)
 482                                         break;
 483                                 /* Link ID */
 484                                 linkid = cfpkt_extr_head_u8(pkt);
 485                                 /* Length */
 486                                 len = cfpkt_extr_head_u8(pkt);
 487                                 /* Param Data */
 488                                 cfpkt_extr_head(pkt, &param, len);
 489                                 break;
 490                         default:
 491                                 pr_warn("Request setup, invalid type (%d)\n",
 492                                         serv);
 493                                 goto error;
 494                         }
 495
 496                         rsp.cmd = cmd;
 497                         rsp.param = linkparam;
 498                         spin_lock_bh(&cfctrl->info_list_lock);
 499                         req = cfctrl_remove_req(cfctrl, &rsp);
 500
 501                         if (CFCTRL_ERR_BIT == (CFCTRL_ERR_BIT & cmdrsp) ||
 502                                 cfpkt_erroneous(pkt)) {
 503                                 pr_err("Invalid O/E bit or parse error "
 504                                                 "on CAIF control channel\n");
 505                                 cfctrl->res.reject_rsp(cfctrl->serv.layer.up,
 506                                                        0,
 507                                                        req ? req->client_layer
 508                                                        : NULL);
 509                         } else {
 510                                 cfctrl->res.linksetup_rsp(cfctrl->serv.
 511                                                           layer.up, linkid,
 512                                                           serv, physlinkid,
 513                                                           req ? req->
 514                                                           client_layer : NULL);
 515                         }
 516
 517                         kfree(req);
 518
 519                         spin_unlock_bh(&cfctrl->info_list_lock);
 520                 }
 521                 break;
 522         case CFCTRL_CMD_LINK_DESTROY:
 523                 linkid = cfpkt_extr_head_u8(pkt);
 524                 cfctrl->res.linkdestroy_rsp(cfctrl->serv.layer.up, linkid);
 525                 break;
 526         case CFCTRL_CMD_LINK_ERR:
 527                 pr_err("Frame Error Indication received\n");
 528                 cfctrl->res.linkerror_ind();
 529                 break;
 530         case CFCTRL_CMD_ENUM:
 531                 cfctrl->res.enum_rsp();
 532                 break;
 533         case CFCTRL_CMD_SLEEP:
 534                 cfctrl->res.sleep_rsp();
 535                 break;
 536         case CFCTRL_CMD_WAKE:
 537                 cfctrl->res.wake_rsp();
 538                 break;
 539         case CFCTRL_CMD_LINK_RECONF:
 540                 cfctrl->res.restart_rsp();
 541                 break;
 542         case CFCTRL_CMD_RADIO_SET:
 543                 cfctrl->res.radioset_rsp();
 544                 break;
 545         default:
 546                 pr_err("Unrecognized Control Frame\n");
 547                 goto error;
 548         }
 549         ret = 0;
 550 error:
 551         cfpkt_destroy(pkt);
 552         return ret;
 553 }
 554
 555 static void cfctrl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 556                            int phyid)
 557 {
 558         struct cfctrl *this = container_obj(layr);
 559         switch (ctrl) {
 560         case _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND:
 561         case CAIF_CTRLCMD_FLOW_OFF_IND:
 562                 spin_lock_bh(&this->info_list_lock);
 563                 if (!list_empty(&this->list))
 564                         pr_debug("Received flow off in control layer\n");
 565                 spin_unlock_bh(&this->info_list_lock);
 566                 break;
 567         case _CAIF_CTRLCMD_PHYIF_DOWN_IND: {
 568                 struct cfctrl_request_info *p, *tmp;
 569
 570                 /* Find all connect request and report failure */
 571                 spin_lock_bh(&this->info_list_lock);
 572                 list_for_each_entry_safe(p, tmp, &this->list, list) {
 573                         if (p->param.phyid == phyid) {
 574                                 list_del(&p->list);
 575                                 p->client_layer->ctrlcmd(p->client_layer,
 576                                                 CAIF_CTRLCMD_INIT_FAIL_RSP,
 577                                                 phyid);
 578                                 kfree(p);
 579                         }
 580                 }
 581                 spin_unlock_bh(&this->info_list_lock);
 582                 break;
 583         }
 584         default:
 585                 break;
 586         }
 587 }
 588
 589 #ifndef CAIF_NO_LOOP
 590 static int handle_loop(struct cfctrl *ctrl, int cmd, struct cfpkt *pkt)
 591 {
 592         static int last_linkid;
 593         static int dec;
 594         u8 linkid, linktype, tmp;
 595         switch (cmd) {
 596         case CFCTRL_CMD_LINK_SETUP:
 597                 spin_lock_bh(&ctrl->loop_linkid_lock);
 598                 if (!dec) {
 599                         for (linkid = last_linkid + 1; linkid < 254; linkid++)
 600                                 if (!ctrl->loop_linkused[linkid])
 601                                         goto found;
 602                 }
 603                 dec = 1;
 604                 for (linkid = last_linkid - 1; linkid > 1; linkid--)
 605                         if (!ctrl->loop_linkused[linkid])
 606                                 goto found;
 607                 spin_unlock_bh(&ctrl->loop_linkid_lock);
 608                 return -1;
 609 found:
 610                 if (linkid < 10)
 611                         dec = 0;
 612
 613                 if (!ctrl->loop_linkused[linkid])
 614                         ctrl->loop_linkused[linkid] = 1;
 615
 616                 last_linkid = linkid;
 617
 618                 cfpkt_add_trail(pkt, &linkid, 1);
 619                 spin_unlock_bh(&ctrl->loop_linkid_lock);
 620                 cfpkt_peek_head(pkt, &linktype, 1);
 621                 if (linktype ==  CFCTRL_SRV_UTIL) {
 622                         tmp = 0x01;
 623                         cfpkt_add_trail(pkt, &tmp, 1);
 624                         cfpkt_add_trail(pkt, &tmp, 1);
 625                 }
 626                 break;
 627
 628         case CFCTRL_CMD_LINK_DESTROY:
 629                 spin_lock_bh(&ctrl->loop_linkid_lock);
 630                 cfpkt_peek_head(pkt, &linkid, 1);
 631                 ctrl->loop_linkused[linkid] = 0;
 632                 spin_unlock_bh(&ctrl->loop_linkid_lock);
 633                 break;
 634         default:
 635                 break;
 636         }
 637         return 0;
 638 }
 639 #endif