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                 kmalloc(sizeof(struct cfctrl), GFP_ATOMIC);
  39         if (!this) {
  40                 pr_warn("Out of memory\n");
  41                 return NULL;
  42         }
  43         caif_assert(offsetof(struct cfctrl, serv.layer) == 0);
  44         memset(&dev_info, 0, sizeof(dev_info));
  45         dev_info.id = 0xff;
  46         memset(this, 0, sizeof(*this));
  47         cfsrvl_init(&this->serv, 0, &dev_info, false);
  48         atomic_set(&this->req_seq_no, 1);
  49         atomic_set(&this->rsp_seq_no, 1);
  50         this->serv.layer.receive = cfctrl_recv;
  51         sprintf(this->serv.layer.name, "ctrl");
  52         this->serv.layer.ctrlcmd = cfctrl_ctrlcmd;
  53 #ifndef CAIF_NO_LOOP
  54         spin_lock_init(&this->loop_linkid_lock);
  55         this->loop_linkid = 1;
  56 #endif
  57         spin_lock_init(&this->info_list_lock);
  58         INIT_LIST_HEAD(&this->list);
  59         return &this->serv.layer;
  60 }
  61
  62 void cfctrl_remove(struct cflayer *layer)
  63 {
  64         struct cfctrl_request_info *p, *tmp;
  65         struct cfctrl *ctrl = container_obj(layer);
  66
  67         spin_lock_bh(&ctrl->info_list_lock);
  68         list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
  69                 list_del(&p->list);
  70                 kfree(p);
  71         }
  72         spin_unlock_bh(&ctrl->info_list_lock);
  73         kfree(layer);
  74 }
  75
  76 static bool param_eq(const struct cfctrl_link_param *p1,
  77                         const struct cfctrl_link_param *p2)
  78 {
  79         bool eq =
  80             p1->linktype == p2->linktype &&
  81             p1->priority == p2->priority &&
  82             p1->phyid == p2->phyid &&
  83             p1->endpoint == p2->endpoint && p1->chtype == p2->chtype;
  84
  85         if (!eq)
  86                 return false;
  87
  88         switch (p1->linktype) {
  89         case CFCTRL_SRV_VEI:
  90                 return true;
  91         case CFCTRL_SRV_DATAGRAM:
  92                 return p1->u.datagram.connid == p2->u.datagram.connid;
  93         case CFCTRL_SRV_RFM:
  94                 return
  95                     p1->u.rfm.connid == p2->u.rfm.connid &&
  96                     strcmp(p1->u.rfm.volume, p2->u.rfm.volume) == 0;
  97         case CFCTRL_SRV_UTIL:
  98                 return
  99                     p1->u.utility.fifosize_kb == p2->u.utility.fifosize_kb
 100                     && p1->u.utility.fifosize_bufs ==
 101                     p2->u.utility.fifosize_bufs
 102                     && strcmp(p1->u.utility.name, p2->u.utility.name) == 0
 103                     && p1->u.utility.paramlen == p2->u.utility.paramlen
 104                     && memcmp(p1->u.utility.params, p2->u.utility.params,
 105                               p1->u.utility.paramlen) == 0;
 106
 107         case CFCTRL_SRV_VIDEO:
 108                 return p1->u.video.connid == p2->u.video.connid;
 109         case CFCTRL_SRV_DBG:
 110                 return true;
 111         case CFCTRL_SRV_DECM:
 112                 return false;
 113         default:
 114                 return false;
 115         }
 116         return false;
 117 }
 118
 119 static bool cfctrl_req_eq(const struct cfctrl_request_info *r1,
 120                           const struct cfctrl_request_info *r2)
 121 {
 122         if (r1->cmd != r2->cmd)
 123                 return false;
 124         if (r1->cmd == CFCTRL_CMD_LINK_SETUP)
 125                 return param_eq(&r1->param, &r2->param);
 126         else
 127                 return r1->channel_id == r2->channel_id;
 128 }
 129
 130 /* Insert request at the end */
 131 static void cfctrl_insert_req(struct cfctrl *ctrl,
 132                               struct cfctrl_request_info *req)
 133 {
 134         spin_lock_bh(&ctrl->info_list_lock);
 135         atomic_inc(&ctrl->req_seq_no);
 136         req->sequence_no = atomic_read(&ctrl->req_seq_no);
 137         list_add_tail(&req->list, &ctrl->list);
 138         spin_unlock_bh(&ctrl->info_list_lock);
 139 }
 140
 141 /* Compare and remove request */
 142 static struct cfctrl_request_info *cfctrl_remove_req(struct cfctrl *ctrl,
 143                                                 struct cfctrl_request_info *req)
 144 {
 145         struct cfctrl_request_info *p, *tmp, *first;
 146
 147         first = list_first_entry(&ctrl->list, struct cfctrl_request_info, list);
 148
 149         list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
 150                 if (cfctrl_req_eq(req, p)) {
 151                         if (p != first)
 152                                 pr_warn("Requests are not received in order\n");
 153
 154                         atomic_set(&ctrl->rsp_seq_no,
 155                                          p->sequence_no);
 156                         list_del(&p->list);
 157                         goto out;
 158                 }
 159         }
 160         p = NULL;
 161 out:
 162         return p;
 163 }
 164
 165 struct cfctrl_rsp *cfctrl_get_respfuncs(struct cflayer *layer)
 166 {
 167         struct cfctrl *this = container_obj(layer);
 168         return &this->res;
 169 }
 170
 171 static void init_info(struct caif_payload_info *info, struct cfctrl *cfctrl)
 172 {
 173         info->hdr_len = 0;
 174         info->channel_id = cfctrl->serv.layer.id;
 175         info->dev_info = &cfctrl->serv.dev_info;
 176 }
 177
 178 void cfctrl_enum_req(struct cflayer *layer, u8 physlinkid)
 179 {
 180         struct cfctrl *cfctrl = container_obj(layer);
 181         struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
 182         struct cflayer *dn = cfctrl->serv.layer.dn;
 183         if (!pkt) {
 184                 pr_warn("Out of memory\n");
 185                 return;
 186         }
 187         if (!dn) {
 188                 pr_debug("not able to send enum request\n");
 189                 return;
 190         }
 191         caif_assert(offsetof(struct cfctrl, serv.layer) == 0);
 192         init_info(cfpkt_info(pkt), cfctrl);
 193         cfpkt_info(pkt)->dev_info->id = physlinkid;
 194         cfctrl->serv.dev_info.id = physlinkid;
 195         cfpkt_addbdy(pkt, CFCTRL_CMD_ENUM);
 196         cfpkt_addbdy(pkt, physlinkid);
 197         dn->transmit(dn, pkt);
 198 }
 199
 200 int cfctrl_linkup_request(struct cflayer *layer,
 201                            struct cfctrl_link_param *param,
 202                            struct cflayer *user_layer)
 203 {
 204         struct cfctrl *cfctrl = container_obj(layer);
 205         u32 tmp32;
 206         u16 tmp16;
 207         u8 tmp8;
 208         struct cfctrl_request_info *req;
 209         int ret;
 210         char utility_name[16];
 211         struct cfpkt *pkt;
 212         struct cflayer *dn = cfctrl->serv.layer.dn;
 213
 214         if (!dn) {
 215                 pr_debug("not able to send linkup request\n");
 216                 return -ENODEV;
 217         }
 218
 219         if (cfctrl_cancel_req(layer, user_layer) > 0) {
 220                 /* Slight Paranoia, check if already connecting */
 221                 pr_err("Duplicate connect request for same client\n");
 222                 WARN_ON(1);
 223                 return -EALREADY;
 224         }
 225
 226         pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
 227         if (!pkt) {
 228                 pr_warn("Out of memory\n");
 229                 return -ENOMEM;
 230         }
 231         cfpkt_addbdy(pkt, CFCTRL_CMD_LINK_SETUP);
 232         cfpkt_addbdy(pkt, (param->chtype << 4) | param->linktype);
 233         cfpkt_addbdy(pkt, (param->priority << 3) | param->phyid);
 234         cfpkt_addbdy(pkt, param->endpoint & 0x03);
 235
 236         switch (param->linktype) {
 237         case CFCTRL_SRV_VEI:
 238                 break;
 239         case CFCTRL_SRV_VIDEO:
 240                 cfpkt_addbdy(pkt, (u8) param->u.video.connid);
 241                 break;
 242         case CFCTRL_SRV_DBG:
 243                 break;
 244         case CFCTRL_SRV_DATAGRAM:
 245                 tmp32 = cpu_to_le32(param->u.datagram.connid);
 246                 cfpkt_add_body(pkt, &tmp32, 4);
 247                 break;
 248         case CFCTRL_SRV_RFM:
 249                 /* Construct a frame, convert DatagramConnectionID to network
 250                  * format long and copy it out...
 251                  */
 252                 tmp32 = cpu_to_le32(param->u.rfm.connid);
 253                 cfpkt_add_body(pkt, &tmp32, 4);
 254                 /* Add volume name, including zero termination... */
 255                 cfpkt_add_body(pkt, param->u.rfm.volume,
 256                                strlen(param->u.rfm.volume) + 1);
 257                 break;
 258         case CFCTRL_SRV_UTIL:
 259                 tmp16 = cpu_to_le16(param->u.utility.fifosize_kb);
 260                 cfpkt_add_body(pkt, &tmp16, 2);
 261                 tmp16 = cpu_to_le16(param->u.utility.fifosize_bufs);
 262                 cfpkt_add_body(pkt, &tmp16, 2);
 263                 memset(utility_name, 0, sizeof(utility_name));
 264                 strncpy(utility_name, param->u.utility.name,
 265                         UTILITY_NAME_LENGTH - 1);
 266                 cfpkt_add_body(pkt, utility_name, UTILITY_NAME_LENGTH);
 267                 tmp8 = param->u.utility.paramlen;
 268                 cfpkt_add_body(pkt, &tmp8, 1);
 269                 cfpkt_add_body(pkt, param->u.utility.params,
 270                                param->u.utility.paramlen);
 271                 break;
 272         default:
 273                 pr_warn("Request setup of bad link type = %d\n",
 274                         param->linktype);
 275                 return -EINVAL;
 276         }
 277         req = kzalloc(sizeof(*req), GFP_KERNEL);
 278         if (!req) {
 279                 pr_warn("Out of memory\n");
 280                 return -ENOMEM;
 281         }
 282         req->client_layer = user_layer;
 283         req->cmd = CFCTRL_CMD_LINK_SETUP;
 284         req->param = *param;
 285         cfctrl_insert_req(cfctrl, req);
 286         init_info(cfpkt_info(pkt), cfctrl);
 287         /*
 288          * NOTE:Always send linkup and linkdown request on the same
 289          *      device as the payload. Otherwise old queued up payload
 290          *      might arrive with the newly allocated channel ID.
 291          */
 292         cfpkt_info(pkt)->dev_info->id = param->phyid;
 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         return 0;
 305 }
 306
 307 int cfctrl_linkdown_req(struct cflayer *layer, u8 channelid,
 308                                 struct cflayer *client)
 309 {
 310         int ret;
 311         struct cfctrl *cfctrl = container_obj(layer);
 312         struct cfpkt *pkt = cfpkt_create(CFPKT_CTRL_PKT_LEN);
 313         struct cflayer *dn = cfctrl->serv.layer.dn;
 314
 315         if (!pkt) {
 316                 pr_warn("Out of memory\n");
 317                 return -ENOMEM;
 318         }
 319
 320         if (!dn) {
 321                 pr_debug("not able to send link-down request\n");
 322                 return -ENODEV;
 323         }
 324
 325         cfpkt_addbdy(pkt, CFCTRL_CMD_LINK_DESTROY);
 326         cfpkt_addbdy(pkt, channelid);
 327         init_info(cfpkt_info(pkt), cfctrl);
 328         ret =
 329             dn->transmit(dn, pkt);
 330 #ifndef CAIF_NO_LOOP
 331         cfctrl->loop_linkused[channelid] = 0;
 332 #endif
 333         return ret;
 334 }
 335
 336 int cfctrl_cancel_req(struct cflayer *layr, struct cflayer *adap_layer)
 337 {
 338         struct cfctrl_request_info *p, *tmp;
 339         struct cfctrl *ctrl = container_obj(layr);
 340         int found = 0;
 341         spin_lock_bh(&ctrl->info_list_lock);
 342
 343         list_for_each_entry_safe(p, tmp, &ctrl->list, list) {
 344                 if (p->client_layer == adap_layer) {
 345                         list_del(&p->list);
 346                         kfree(p);
 347                         found++;
 348                 }
 349         }
 350
 351         spin_unlock_bh(&ctrl->info_list_lock);
 352         return found;
 353 }
 354
 355 static int cfctrl_recv(struct cflayer *layer, struct cfpkt *pkt)
 356 {
 357         u8 cmdrsp;
 358         u8 cmd;
 359         int ret = -1;
 360         u16 tmp16;
 361         u8 len;
 362         u8 param[255];
 363         u8 linkid;
 364         struct cfctrl *cfctrl = container_obj(layer);
 365         struct cfctrl_request_info rsp, *req;
 366
 367
 368         cfpkt_extr_head(pkt, &cmdrsp, 1);
 369         cmd = cmdrsp & CFCTRL_CMD_MASK;
 370         if (cmd != CFCTRL_CMD_LINK_ERR
 371             && CFCTRL_RSP_BIT != (CFCTRL_RSP_BIT & cmdrsp)) {
 372                 if (handle_loop(cfctrl, cmd, pkt) != 0)
 373                         cmdrsp |= CFCTRL_ERR_BIT;
 374         }
 375
 376         switch (cmd) {
 377         case CFCTRL_CMD_LINK_SETUP:
 378                 {
 379                         enum cfctrl_srv serv;
 380                         enum cfctrl_srv servtype;
 381                         u8 endpoint;
 382                         u8 physlinkid;
 383                         u8 prio;
 384                         u8 tmp;
 385                         u32 tmp32;
 386                         u8 *cp;
 387                         int i;
 388                         struct cfctrl_link_param linkparam;
 389                         memset(&linkparam, 0, sizeof(linkparam));
 390
 391                         cfpkt_extr_head(pkt, &tmp, 1);
 392
 393                         serv = tmp & CFCTRL_SRV_MASK;
 394                         linkparam.linktype = serv;
 395
 396                         servtype = tmp >> 4;
 397                         linkparam.chtype = servtype;
 398
 399                         cfpkt_extr_head(pkt, &tmp, 1);
 400                         physlinkid = tmp & 0x07;
 401                         prio = tmp >> 3;
 402
 403                         linkparam.priority = prio;
 404                         linkparam.phyid = physlinkid;
 405                         cfpkt_extr_head(pkt, &endpoint, 1);
 406                         linkparam.endpoint = endpoint & 0x03;
 407
 408                         switch (serv) {
 409                         case CFCTRL_SRV_VEI:
 410                         case CFCTRL_SRV_DBG:
 411                                 if (CFCTRL_ERR_BIT & cmdrsp)
 412                                         break;
 413                                 /* Link ID */
 414                                 cfpkt_extr_head(pkt, &linkid, 1);
 415                                 break;
 416                         case CFCTRL_SRV_VIDEO:
 417                                 cfpkt_extr_head(pkt, &tmp, 1);
 418                                 linkparam.u.video.connid = tmp;
 419                                 if (CFCTRL_ERR_BIT & cmdrsp)
 420                                         break;
 421                                 /* Link ID */
 422                                 cfpkt_extr_head(pkt, &linkid, 1);
 423                                 break;
 424
 425                         case CFCTRL_SRV_DATAGRAM:
 426                                 cfpkt_extr_head(pkt, &tmp32, 4);
 427                                 linkparam.u.datagram.connid =
 428                                     le32_to_cpu(tmp32);
 429                                 if (CFCTRL_ERR_BIT & cmdrsp)
 430                                         break;
 431                                 /* Link ID */
 432                                 cfpkt_extr_head(pkt, &linkid, 1);
 433                                 break;
 434                         case CFCTRL_SRV_RFM:
 435                                 /* Construct a frame, convert
 436                                  * DatagramConnectionID
 437                                  * to network format long and copy it out...
 438                                  */
 439                                 cfpkt_extr_head(pkt, &tmp32, 4);
 440                                 linkparam.u.rfm.connid =
 441                                   le32_to_cpu(tmp32);
 442                                 cp = (u8 *) linkparam.u.rfm.volume;
 443                                 for (cfpkt_extr_head(pkt, &tmp, 1);
 444                                      cfpkt_more(pkt) && tmp != '\0';
 445                                      cfpkt_extr_head(pkt, &tmp, 1))
 446                                         *cp++ = tmp;
 447                                 *cp = '\0';
 448
 449                                 if (CFCTRL_ERR_BIT & cmdrsp)
 450                                         break;
 451                                 /* Link ID */
 452                                 cfpkt_extr_head(pkt, &linkid, 1);
 453
 454                                 break;
 455                         case CFCTRL_SRV_UTIL:
 456                                 /* Construct a frame, convert
 457                                  * DatagramConnectionID
 458                                  * to network format long and copy it out...
 459                                  */
 460                                 /* Fifosize KB */
 461                                 cfpkt_extr_head(pkt, &tmp16, 2);
 462                                 linkparam.u.utility.fifosize_kb =
 463                                     le16_to_cpu(tmp16);
 464                                 /* Fifosize bufs */
 465                                 cfpkt_extr_head(pkt, &tmp16, 2);
 466                                 linkparam.u.utility.fifosize_bufs =
 467                                     le16_to_cpu(tmp16);
 468                                 /* name */
 469                                 cp = (u8 *) linkparam.u.utility.name;
 470                                 caif_assert(sizeof(linkparam.u.utility.name)
 471                                              >= UTILITY_NAME_LENGTH);
 472                                 for (i = 0;
 473                                      i < UTILITY_NAME_LENGTH
 474                                      && cfpkt_more(pkt); i++) {
 475                                         cfpkt_extr_head(pkt, &tmp, 1);
 476                                         *cp++ = tmp;
 477                                 }
 478                                 /* Length */
 479                                 cfpkt_extr_head(pkt, &len, 1);
 480                                 linkparam.u.utility.paramlen = len;
 481                                 /* Param Data */
 482                                 cp = linkparam.u.utility.params;
 483                                 while (cfpkt_more(pkt) && len--) {
 484                                         cfpkt_extr_head(pkt, &tmp, 1);
 485                                         *cp++ = tmp;
 486                                 }
 487                                 if (CFCTRL_ERR_BIT & cmdrsp)
 488                                         break;
 489                                 /* Link ID */
 490                                 cfpkt_extr_head(pkt, &linkid, 1);
 491                                 /* Length */
 492                                 cfpkt_extr_head(pkt, &len, 1);
 493                                 /* Param Data */
 494                                 cfpkt_extr_head(pkt, &param, len);
 495                                 break;
 496                         default:
 497                                 pr_warn("Request setup, invalid type (%d)\n",
 498                                         serv);
 499                                 goto error;
 500                         }
 501
 502                         rsp.cmd = cmd;
 503                         rsp.param = linkparam;
 504                         spin_lock_bh(&cfctrl->info_list_lock);
 505                         req = cfctrl_remove_req(cfctrl, &rsp);
 506
 507                         if (CFCTRL_ERR_BIT == (CFCTRL_ERR_BIT & cmdrsp) ||
 508                                 cfpkt_erroneous(pkt)) {
 509                                 pr_err("Invalid O/E bit or parse error "
 510                                                 "on CAIF control channel\n");
 511                                 cfctrl->res.reject_rsp(cfctrl->serv.layer.up,
 512                                                        0,
 513                                                        req ? req->client_layer
 514                                                        : NULL);
 515                         } else {
 516                                 cfctrl->res.linksetup_rsp(cfctrl->serv.
 517                                                           layer.up, linkid,
 518                                                           serv, physlinkid,
 519                                                           req ? req->
 520                                                           client_layer : NULL);
 521                         }
 522
 523                         if (req != NULL)
 524                                 kfree(req);
 525
 526                         spin_unlock_bh(&cfctrl->info_list_lock);
 527                 }
 528                 break;
 529         case CFCTRL_CMD_LINK_DESTROY:
 530                 cfpkt_extr_head(pkt, &linkid, 1);
 531                 cfctrl->res.linkdestroy_rsp(cfctrl->serv.layer.up, linkid);
 532                 break;
 533         case CFCTRL_CMD_LINK_ERR:
 534                 pr_err("Frame Error Indication received\n");
 535                 cfctrl->res.linkerror_ind();
 536                 break;
 537         case CFCTRL_CMD_ENUM:
 538                 cfctrl->res.enum_rsp();
 539                 break;
 540         case CFCTRL_CMD_SLEEP:
 541                 cfctrl->res.sleep_rsp();
 542                 break;
 543         case CFCTRL_CMD_WAKE:
 544                 cfctrl->res.wake_rsp();
 545                 break;
 546         case CFCTRL_CMD_LINK_RECONF:
 547                 cfctrl->res.restart_rsp();
 548                 break;
 549         case CFCTRL_CMD_RADIO_SET:
 550                 cfctrl->res.radioset_rsp();
 551                 break;
 552         default:
 553                 pr_err("Unrecognized Control Frame\n");
 554                 goto error;
 555                 break;
 556         }
 557         ret = 0;
 558 error:
 559         cfpkt_destroy(pkt);
 560         return ret;
 561 }
 562
 563 static void cfctrl_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
 564                         int phyid)
 565 {
 566         struct cfctrl *this = container_obj(layr);
 567         switch (ctrl) {
 568         case _CAIF_CTRLCMD_PHYIF_FLOW_OFF_IND:
 569         case CAIF_CTRLCMD_FLOW_OFF_IND:
 570                 spin_lock_bh(&this->info_list_lock);
 571                 if (!list_empty(&this->list))
 572                         pr_debug("Received flow off in control layer\n");
 573                 spin_unlock_bh(&this->info_list_lock);
 574                 break;
 575         case _CAIF_CTRLCMD_PHYIF_DOWN_IND: {
 576                 struct cfctrl_request_info *p, *tmp;
 577
 578                 /* Find all connect request and report failure */
 579                 spin_lock_bh(&this->info_list_lock);
 580                 list_for_each_entry_safe(p, tmp, &this->list, list) {
 581                         if (p->param.phyid == phyid) {
 582                                 list_del(&p->list);
 583                                 p->client_layer->ctrlcmd(p->client_layer,
 584                                                 CAIF_CTRLCMD_INIT_FAIL_RSP,
 585                                                 phyid);
 586                                 kfree(p);
 587                         }
 588                 }
 589                 spin_unlock_bh(&this->info_list_lock);
 590                 break;
 591         }
 592         default:
 593                 break;
 594         }
 595 }
 596
 597 #ifndef CAIF_NO_LOOP
 598 static int handle_loop(struct cfctrl *ctrl, int cmd, struct cfpkt *pkt)
 599 {
 600         static int last_linkid;
 601         static int dec;
 602         u8 linkid, linktype, tmp;
 603         switch (cmd) {
 604         case CFCTRL_CMD_LINK_SETUP:
 605                 spin_lock_bh(&ctrl->loop_linkid_lock);
 606                 if (!dec) {
 607                         for (linkid = last_linkid + 1; linkid < 255; linkid++)
 608                                 if (!ctrl->loop_linkused[linkid])
 609                                         goto found;
 610                 }
 611                 dec = 1;
 612                 for (linkid = last_linkid - 1; linkid > 0; linkid--)
 613                         if (!ctrl->loop_linkused[linkid])
 614                                 goto found;
 615                 spin_unlock_bh(&ctrl->loop_linkid_lock);
 616
 617 found:
 618                 if (linkid < 10)
 619                         dec = 0;
 620
 621                 if (!ctrl->loop_linkused[linkid])
 622                         ctrl->loop_linkused[linkid] = 1;
 623
 624                 last_linkid = linkid;
 625
 626                 cfpkt_add_trail(pkt, &linkid, 1);
 627                 spin_unlock_bh(&ctrl->loop_linkid_lock);
 628                 cfpkt_peek_head(pkt, &linktype, 1);
 629                 if (linktype ==  CFCTRL_SRV_UTIL) {
 630                         tmp = 0x01;
 631                         cfpkt_add_trail(pkt, &tmp, 1);
 632                         cfpkt_add_trail(pkt, &tmp, 1);
 633                 }
 634                 break;
 635
 636         case CFCTRL_CMD_LINK_DESTROY:
 637                 spin_lock_bh(&ctrl->loop_linkid_lock);
 638                 cfpkt_peek_head(pkt, &linkid, 1);
 639                 ctrl->loop_linkused[linkid] = 0;
 640                 spin_unlock_bh(&ctrl->loop_linkid_lock);
 641                 break;
 642         default:
 643                 break;
 644         }
 645         return 0;
 646 }
 647 #endif