net/dsa/dsa2.c

   1 /*
   2  * net/dsa/dsa2.c - Hardware switch handling, binding version 2
   3  * Copyright (c) 2008-2009 Marvell Semiconductor
   4  * Copyright (c) 2013 Florian Fainelli <[email protected]>
   5  * Copyright (c) 2016 Andrew Lunn <[email protected]>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12
  13 #include <linux/device.h>
  14 #include <linux/err.h>
  15 #include <linux/list.h>
  16 #include <linux/netdevice.h>
  17 #include <linux/slab.h>
  18 #include <linux/rtnetlink.h>
  19 #include <linux/of.h>
  20 #include <linux/of_net.h>
  21
  22 #include "dsa_priv.h"
  23
  24 static LIST_HEAD(dsa_tree_list);
  25 static DEFINE_MUTEX(dsa2_mutex);
  26
  27 static const struct devlink_ops dsa_devlink_ops = {
  28 };
  29
  30 static struct dsa_switch_tree *dsa_tree_find(int index)
  31 {
  32         struct dsa_switch_tree *dst;
  33
  34         list_for_each_entry(dst, &dsa_tree_list, list)
  35                 if (dst->index == index)
  36                         return dst;
  37
  38         return NULL;
  39 }
  40
  41 static struct dsa_switch_tree *dsa_tree_alloc(int index)
  42 {
  43         struct dsa_switch_tree *dst;
  44
  45         dst = kzalloc(sizeof(*dst), GFP_KERNEL);
  46         if (!dst)
  47                 return NULL;
  48
  49         dst->index = index;
  50
  51         INIT_LIST_HEAD(&dst->list);
  52         list_add_tail(&dsa_tree_list, &dst->list);
  53
  54         kref_init(&dst->refcount);
  55
  56         return dst;
  57 }
  58
  59 static void dsa_tree_free(struct dsa_switch_tree *dst)
  60 {
  61         list_del(&dst->list);
  62         kfree(dst);
  63 }
  64
  65 static struct dsa_switch_tree *dsa_tree_get(struct dsa_switch_tree *dst)
  66 {
  67         if (dst)
  68                 kref_get(&dst->refcount);
  69
  70         return dst;
  71 }
  72
  73 static struct dsa_switch_tree *dsa_tree_touch(int index)
  74 {
  75         struct dsa_switch_tree *dst;
  76
  77         dst = dsa_tree_find(index);
  78         if (dst)
  79                 return dsa_tree_get(dst);
  80         else
  81                 return dsa_tree_alloc(index);
  82 }
  83
  84 static void dsa_tree_release(struct kref *ref)
  85 {
  86         struct dsa_switch_tree *dst;
  87
  88         dst = container_of(ref, struct dsa_switch_tree, refcount);
  89
  90         dsa_tree_free(dst);
  91 }
  92
  93 static void dsa_tree_put(struct dsa_switch_tree *dst)
  94 {
  95         if (dst)
  96                 kref_put(&dst->refcount, dsa_tree_release);
  97 }
  98
  99 static bool dsa_port_is_dsa(struct dsa_port *port)
 100 {
 101         return port->type == DSA_PORT_TYPE_DSA;
 102 }
 103
 104 static bool dsa_port_is_cpu(struct dsa_port *port)
 105 {
 106         return port->type == DSA_PORT_TYPE_CPU;
 107 }
 108
 109 static bool dsa_port_is_user(struct dsa_port *dp)
 110 {
 111         return dp->type == DSA_PORT_TYPE_USER;
 112 }
 113
 114 static struct dsa_port *dsa_tree_find_port_by_node(struct dsa_switch_tree *dst,
 115                                                    struct device_node *dn)
 116 {
 117         struct dsa_switch *ds;
 118         struct dsa_port *dp;
 119         int device, port;
 120
 121         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 122                 ds = dst->ds[device];
 123                 if (!ds)
 124                         continue;
 125
 126                 for (port = 0; port < ds->num_ports; port++) {
 127                         dp = &ds->ports[port];
 128
 129                         if (dp->dn == dn)
 130                                 return dp;
 131                 }
 132         }
 133
 134         return NULL;
 135 }
 136
 137 static bool dsa_port_setup_routing_table(struct dsa_port *dp)
 138 {
 139         struct dsa_switch *ds = dp->ds;
 140         struct dsa_switch_tree *dst = ds->dst;
 141         struct device_node *dn = dp->dn;
 142         struct of_phandle_iterator it;
 143         struct dsa_port *link_dp;
 144         int err;
 145
 146         of_for_each_phandle(&it, err, dn, "link", NULL, 0) {
 147                 link_dp = dsa_tree_find_port_by_node(dst, it.node);
 148                 if (!link_dp) {
 149                         of_node_put(it.node);
 150                         return false;
 151                 }
 152
 153                 ds->rtable[link_dp->ds->index] = dp->index;
 154         }
 155
 156         return true;
 157 }
 158
 159 static bool dsa_switch_setup_routing_table(struct dsa_switch *ds)
 160 {
 161         bool complete = true;
 162         struct dsa_port *dp;
 163         int i;
 164
 165         for (i = 0; i < DSA_MAX_SWITCHES; i++)
 166                 ds->rtable[i] = DSA_RTABLE_NONE;
 167
 168         for (i = 0; i < ds->num_ports; i++) {
 169                 dp = &ds->ports[i];
 170
 171                 if (dsa_port_is_dsa(dp)) {
 172                         complete = dsa_port_setup_routing_table(dp);
 173                         if (!complete)
 174                                 break;
 175                 }
 176         }
 177
 178         return complete;
 179 }
 180
 181 static bool dsa_tree_setup_routing_table(struct dsa_switch_tree *dst)
 182 {
 183         struct dsa_switch *ds;
 184         bool complete = true;
 185         int device;
 186
 187         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 188                 ds = dst->ds[device];
 189                 if (!ds)
 190                         continue;
 191
 192                 complete = dsa_switch_setup_routing_table(ds);
 193                 if (!complete)
 194                         break;
 195         }
 196
 197         return complete;
 198 }
 199
 200 static struct dsa_port *dsa_tree_find_first_cpu(struct dsa_switch_tree *dst)
 201 {
 202         struct dsa_switch *ds;
 203         struct dsa_port *dp;
 204         int device, port;
 205
 206         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 207                 ds = dst->ds[device];
 208                 if (!ds)
 209                         continue;
 210
 211                 for (port = 0; port < ds->num_ports; port++) {
 212                         dp = &ds->ports[port];
 213
 214                         if (dsa_port_is_cpu(dp))
 215                                 return dp;
 216                 }
 217         }
 218
 219         return NULL;
 220 }
 221
 222 static int dsa_tree_setup_default_cpu(struct dsa_switch_tree *dst)
 223 {
 224         struct dsa_switch *ds;
 225         struct dsa_port *dp;
 226         int device, port;
 227
 228         /* DSA currently only supports a single CPU port */
 229         dst->cpu_dp = dsa_tree_find_first_cpu(dst);
 230         if (!dst->cpu_dp) {
 231                 pr_warn("Tree has no master device\n");
 232                 return -EINVAL;
 233         }
 234
 235         /* Assign the default CPU port to all ports of the fabric */
 236         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 237                 ds = dst->ds[device];
 238                 if (!ds)
 239                         continue;
 240
 241                 for (port = 0; port < ds->num_ports; port++) {
 242                         dp = &ds->ports[port];
 243
 244                         if (dsa_port_is_user(dp) || dsa_port_is_dsa(dp))
 245                                 dp->cpu_dp = dst->cpu_dp;
 246                 }
 247         }
 248
 249         return 0;
 250 }
 251
 252 static void dsa_tree_teardown_default_cpu(struct dsa_switch_tree *dst)
 253 {
 254         /* DSA currently only supports a single CPU port */
 255         dst->cpu_dp = NULL;
 256 }
 257
 258 static int dsa_port_setup(struct dsa_port *dp)
 259 {
 260         struct dsa_switch *ds = dp->ds;
 261         int err = 0;
 262
 263         memset(&dp->devlink_port, 0, sizeof(dp->devlink_port));
 264
 265         if (dp->type != DSA_PORT_TYPE_UNUSED)
 266                 err = devlink_port_register(ds->devlink, &dp->devlink_port,
 267                                             dp->index);
 268         if (err)
 269                 return err;
 270
 271         switch (dp->type) {
 272         case DSA_PORT_TYPE_UNUSED:
 273                 break;
 274         case DSA_PORT_TYPE_CPU:
 275         case DSA_PORT_TYPE_DSA:
 276                 err = dsa_port_link_register_of(dp);
 277                 if (err) {
 278                         dev_err(ds->dev, "failed to setup link for port %d.%d\n",
 279                                 ds->index, dp->index);
 280                         return err;
 281                 }
 282                 break;
 283         case DSA_PORT_TYPE_USER:
 284                 err = dsa_slave_create(dp);
 285                 if (err)
 286                         dev_err(ds->dev, "failed to create slave for port %d.%d\n",
 287                                 ds->index, dp->index);
 288                 else
 289                         devlink_port_type_eth_set(&dp->devlink_port, dp->slave);
 290                 break;
 291         }
 292
 293         return 0;
 294 }
 295
 296 static void dsa_port_teardown(struct dsa_port *dp)
 297 {
 298         if (dp->type != DSA_PORT_TYPE_UNUSED)
 299                 devlink_port_unregister(&dp->devlink_port);
 300
 301         switch (dp->type) {
 302         case DSA_PORT_TYPE_UNUSED:
 303                 break;
 304         case DSA_PORT_TYPE_CPU:
 305         case DSA_PORT_TYPE_DSA:
 306                 dsa_port_link_unregister_of(dp);
 307                 break;
 308         case DSA_PORT_TYPE_USER:
 309                 if (dp->slave) {
 310                         dsa_slave_destroy(dp->slave);
 311                         dp->slave = NULL;
 312                 }
 313                 break;
 314         }
 315 }
 316
 317 static int dsa_switch_setup(struct dsa_switch *ds)
 318 {
 319         int err;
 320
 321         /* Initialize ds->phys_mii_mask before registering the slave MDIO bus
 322          * driver and before ops->setup() has run, since the switch drivers and
 323          * the slave MDIO bus driver rely on these values for probing PHY
 324          * devices or not
 325          */
 326         ds->phys_mii_mask |= dsa_user_ports(ds);
 327
 328         /* Add the switch to devlink before calling setup, so that setup can
 329          * add dpipe tables
 330          */
 331         ds->devlink = devlink_alloc(&dsa_devlink_ops, 0);
 332         if (!ds->devlink)
 333                 return -ENOMEM;
 334
 335         err = devlink_register(ds->devlink, ds->dev);
 336         if (err)
 337                 return err;
 338
 339         err = ds->ops->setup(ds);
 340         if (err < 0)
 341                 return err;
 342
 343         err = dsa_switch_register_notifier(ds);
 344         if (err)
 345                 return err;
 346
 347         if (!ds->slave_mii_bus && ds->ops->phy_read) {
 348                 ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
 349                 if (!ds->slave_mii_bus)
 350                         return -ENOMEM;
 351
 352                 dsa_slave_mii_bus_init(ds);
 353
 354                 err = mdiobus_register(ds->slave_mii_bus);
 355                 if (err < 0)
 356                         return err;
 357         }
 358
 359         return 0;
 360 }
 361
 362 static void dsa_switch_teardown(struct dsa_switch *ds)
 363 {
 364         if (ds->slave_mii_bus && ds->ops->phy_read)
 365                 mdiobus_unregister(ds->slave_mii_bus);
 366
 367         dsa_switch_unregister_notifier(ds);
 368
 369         if (ds->devlink) {
 370                 devlink_unregister(ds->devlink);
 371                 devlink_free(ds->devlink);
 372                 ds->devlink = NULL;
 373         }
 374
 375 }
 376
 377 static int dsa_tree_setup_switches(struct dsa_switch_tree *dst)
 378 {
 379         struct dsa_switch *ds;
 380         struct dsa_port *dp;
 381         int device, port;
 382         int err;
 383
 384         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 385                 ds = dst->ds[device];
 386                 if (!ds)
 387                         continue;
 388
 389                 err = dsa_switch_setup(ds);
 390                 if (err)
 391                         return err;
 392
 393                 for (port = 0; port < ds->num_ports; port++) {
 394                         dp = &ds->ports[port];
 395
 396                         err = dsa_port_setup(dp);
 397                         if (err)
 398                                 return err;
 399                 }
 400         }
 401
 402         return 0;
 403 }
 404
 405 static void dsa_tree_teardown_switches(struct dsa_switch_tree *dst)
 406 {
 407         struct dsa_switch *ds;
 408         struct dsa_port *dp;
 409         int device, port;
 410
 411         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 412                 ds = dst->ds[device];
 413                 if (!ds)
 414                         continue;
 415
 416                 for (port = 0; port < ds->num_ports; port++) {
 417                         dp = &ds->ports[port];
 418
 419                         dsa_port_teardown(dp);
 420                 }
 421
 422                 dsa_switch_teardown(ds);
 423         }
 424 }
 425
 426 static int dsa_tree_setup_master(struct dsa_switch_tree *dst)
 427 {
 428         struct dsa_port *cpu_dp = dst->cpu_dp;
 429         struct net_device *master = cpu_dp->master;
 430
 431         /* DSA currently supports a single pair of CPU port and master device */
 432         return dsa_master_setup(master, cpu_dp);
 433 }
 434
 435 static void dsa_tree_teardown_master(struct dsa_switch_tree *dst)
 436 {
 437         struct dsa_port *cpu_dp = dst->cpu_dp;
 438         struct net_device *master = cpu_dp->master;
 439
 440         return dsa_master_teardown(master);
 441 }
 442
 443 static int dsa_tree_setup(struct dsa_switch_tree *dst)
 444 {
 445         bool complete;
 446         int err;
 447
 448         if (dst->setup) {
 449                 pr_err("DSA: tree %d already setup! Disjoint trees?\n",
 450                        dst->index);
 451                 return -EEXIST;
 452         }
 453
 454         complete = dsa_tree_setup_routing_table(dst);
 455         if (!complete)
 456                 return 0;
 457
 458         err = dsa_tree_setup_default_cpu(dst);
 459         if (err)
 460                 return err;
 461
 462         err = dsa_tree_setup_switches(dst);
 463         if (err)
 464                 return err;
 465
 466         err = dsa_tree_setup_master(dst);
 467         if (err)
 468                 return err;
 469
 470         dst->setup = true;
 471
 472         pr_info("DSA: tree %d setup\n", dst->index);
 473
 474         return 0;
 475 }
 476
 477 static void dsa_tree_teardown(struct dsa_switch_tree *dst)
 478 {
 479         if (!dst->setup)
 480                 return;
 481
 482         dsa_tree_teardown_master(dst);
 483
 484         dsa_tree_teardown_switches(dst);
 485
 486         dsa_tree_teardown_default_cpu(dst);
 487
 488         pr_info("DSA: tree %d torn down\n", dst->index);
 489
 490         dst->setup = false;
 491 }
 492
 493 static void dsa_tree_remove_switch(struct dsa_switch_tree *dst,
 494                                    unsigned int index)
 495 {
 496         dsa_tree_teardown(dst);
 497
 498         dst->ds[index] = NULL;
 499         dsa_tree_put(dst);
 500 }
 501
 502 static int dsa_tree_add_switch(struct dsa_switch_tree *dst,
 503                                struct dsa_switch *ds)
 504 {
 505         unsigned int index = ds->index;
 506         int err;
 507
 508         if (dst->ds[index])
 509                 return -EBUSY;
 510
 511         dsa_tree_get(dst);
 512         dst->ds[index] = ds;
 513
 514         err = dsa_tree_setup(dst);
 515         if (err)
 516                 dsa_tree_remove_switch(dst, index);
 517
 518         return err;
 519 }
 520
 521 static int dsa_port_parse_user(struct dsa_port *dp, const char *name)
 522 {
 523         if (!name)
 524                 name = "eth%d";
 525
 526         dp->type = DSA_PORT_TYPE_USER;
 527         dp->name = name;
 528
 529         return 0;
 530 }
 531
 532 static int dsa_port_parse_dsa(struct dsa_port *dp)
 533 {
 534         dp->type = DSA_PORT_TYPE_DSA;
 535
 536         return 0;
 537 }
 538
 539 static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master)
 540 {
 541         struct dsa_switch *ds = dp->ds;
 542         struct dsa_switch_tree *dst = ds->dst;
 543         const struct dsa_device_ops *tag_ops;
 544         enum dsa_tag_protocol tag_protocol;
 545
 546         tag_protocol = ds->ops->get_tag_protocol(ds, dp->index);
 547         tag_ops = dsa_resolve_tag_protocol(tag_protocol);
 548         if (IS_ERR(tag_ops)) {
 549                 dev_warn(ds->dev, "No tagger for this switch\n");
 550                 return PTR_ERR(tag_ops);
 551         }
 552
 553         dp->type = DSA_PORT_TYPE_CPU;
 554         dp->rcv = tag_ops->rcv;
 555         dp->tag_ops = tag_ops;
 556         dp->master = master;
 557         dp->dst = dst;
 558
 559         return 0;
 560 }
 561
 562 static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 563 {
 564         struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
 565         const char *name = of_get_property(dn, "label", NULL);
 566         bool link = of_property_read_bool(dn, "link");
 567
 568         dp->dn = dn;
 569
 570         if (ethernet) {
 571                 struct net_device *master;
 572
 573                 master = of_find_net_device_by_node(ethernet);
 574                 if (!master)
 575                         return -EPROBE_DEFER;
 576
 577                 return dsa_port_parse_cpu(dp, master);
 578         }
 579
 580         if (link)
 581                 return dsa_port_parse_dsa(dp);
 582
 583         return dsa_port_parse_user(dp, name);
 584 }
 585
 586 static int dsa_switch_parse_ports_of(struct dsa_switch *ds,
 587                                      struct device_node *dn)
 588 {
 589         struct device_node *ports, *port;
 590         struct dsa_port *dp;
 591         u32 reg;
 592         int err;
 593
 594         ports = of_get_child_by_name(dn, "ports");
 595         if (!ports) {
 596                 dev_err(ds->dev, "no ports child node found\n");
 597                 return -EINVAL;
 598         }
 599
 600         for_each_available_child_of_node(ports, port) {
 601                 err = of_property_read_u32(port, "reg", &reg);
 602                 if (err)
 603                         return err;
 604
 605                 if (reg >= ds->num_ports)
 606                         return -EINVAL;
 607
 608                 dp = &ds->ports[reg];
 609
 610                 err = dsa_port_parse_of(dp, port);
 611                 if (err)
 612                         return err;
 613         }
 614
 615         return 0;
 616 }
 617
 618 static int dsa_switch_parse_member_of(struct dsa_switch *ds,
 619                                       struct device_node *dn)
 620 {
 621         u32 m[2] = { 0, 0 };
 622         int sz;
 623
 624         /* Don't error out if this optional property isn't found */
 625         sz = of_property_read_variable_u32_array(dn, "dsa,member", m, 2, 2);
 626         if (sz < 0 && sz != -EINVAL)
 627                 return sz;
 628
 629         ds->index = m[1];
 630         if (ds->index >= DSA_MAX_SWITCHES)
 631                 return -EINVAL;
 632
 633         ds->dst = dsa_tree_touch(m[0]);
 634         if (!ds->dst)
 635                 return -ENOMEM;
 636
 637         return 0;
 638 }
 639
 640 static int dsa_switch_parse_of(struct dsa_switch *ds, struct device_node *dn)
 641 {
 642         int err;
 643
 644         err = dsa_switch_parse_member_of(ds, dn);
 645         if (err)
 646                 return err;
 647
 648         return dsa_switch_parse_ports_of(ds, dn);
 649 }
 650
 651 static int dsa_port_parse(struct dsa_port *dp, const char *name,
 652                           struct device *dev)
 653 {
 654         if (!strcmp(name, "cpu")) {
 655                 struct net_device *master;
 656
 657                 master = dsa_dev_to_net_device(dev);
 658                 if (!master)
 659                         return -EPROBE_DEFER;
 660
 661                 dev_put(master);
 662
 663                 return dsa_port_parse_cpu(dp, master);
 664         }
 665
 666         if (!strcmp(name, "dsa"))
 667                 return dsa_port_parse_dsa(dp);
 668
 669         return dsa_port_parse_user(dp, name);
 670 }
 671
 672 static int dsa_switch_parse_ports(struct dsa_switch *ds,
 673                                   struct dsa_chip_data *cd)
 674 {
 675         bool valid_name_found = false;
 676         struct dsa_port *dp;
 677         struct device *dev;
 678         const char *name;
 679         unsigned int i;
 680         int err;
 681
 682         for (i = 0; i < DSA_MAX_PORTS; i++) {
 683                 name = cd->port_names[i];
 684                 dev = cd->netdev[i];
 685                 dp = &ds->ports[i];
 686
 687                 if (!name)
 688                         continue;
 689
 690                 err = dsa_port_parse(dp, name, dev);
 691                 if (err)
 692                         return err;
 693
 694                 valid_name_found = true;
 695         }
 696
 697         if (!valid_name_found && i == DSA_MAX_PORTS)
 698                 return -EINVAL;
 699
 700         return 0;
 701 }
 702
 703 static int dsa_switch_parse(struct dsa_switch *ds, struct dsa_chip_data *cd)
 704 {
 705         ds->cd = cd;
 706
 707         /* We don't support interconnected switches nor multiple trees via
 708          * platform data, so this is the unique switch of the tree.
 709          */
 710         ds->index = 0;
 711         ds->dst = dsa_tree_touch(0);
 712         if (!ds->dst)
 713                 return -ENOMEM;
 714
 715         return dsa_switch_parse_ports(ds, cd);
 716 }
 717
 718 static int dsa_switch_add(struct dsa_switch *ds)
 719 {
 720         struct dsa_switch_tree *dst = ds->dst;
 721
 722         return dsa_tree_add_switch(dst, ds);
 723 }
 724
 725 static int dsa_switch_probe(struct dsa_switch *ds)
 726 {
 727         struct dsa_chip_data *pdata = ds->dev->platform_data;
 728         struct device_node *np = ds->dev->of_node;
 729         int err;
 730
 731         if (np)
 732                 err = dsa_switch_parse_of(ds, np);
 733         else if (pdata)
 734                 err = dsa_switch_parse(ds, pdata);
 735         else
 736                 err = -ENODEV;
 737
 738         if (err)
 739                 return err;
 740
 741         return dsa_switch_add(ds);
 742 }
 743
 744 struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n)
 745 {
 746         size_t size = sizeof(struct dsa_switch) + n * sizeof(struct dsa_port);
 747         struct dsa_switch *ds;
 748         int i;
 749
 750         ds = devm_kzalloc(dev, size, GFP_KERNEL);
 751         if (!ds)
 752                 return NULL;
 753
 754         ds->dev = dev;
 755         ds->num_ports = n;
 756
 757         for (i = 0; i < ds->num_ports; ++i) {
 758                 ds->ports[i].index = i;
 759                 ds->ports[i].ds = ds;
 760         }
 761
 762         return ds;
 763 }
 764 EXPORT_SYMBOL_GPL(dsa_switch_alloc);
 765
 766 int dsa_register_switch(struct dsa_switch *ds)
 767 {
 768         int err;
 769
 770         mutex_lock(&dsa2_mutex);
 771         err = dsa_switch_probe(ds);
 772         dsa_tree_put(ds->dst);
 773         mutex_unlock(&dsa2_mutex);
 774
 775         return err;
 776 }
 777 EXPORT_SYMBOL_GPL(dsa_register_switch);
 778
 779 static void dsa_switch_remove(struct dsa_switch *ds)
 780 {
 781         struct dsa_switch_tree *dst = ds->dst;
 782         unsigned int index = ds->index;
 783
 784         dsa_tree_remove_switch(dst, index);
 785 }
 786
 787 void dsa_unregister_switch(struct dsa_switch *ds)
 788 {
 789         mutex_lock(&dsa2_mutex);
 790         dsa_switch_remove(ds);
 791         mutex_unlock(&dsa2_mutex);
 792 }
 793 EXPORT_SYMBOL_GPL(dsa_unregister_switch);