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 <florian@openwrt.org>
   5  * Copyright (c) 2016 Andrew Lunn <andrew@lunn.ch>
   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))
 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;
 262
 263         memset(&dp->devlink_port, 0, sizeof(dp->devlink_port));
 264
 265         err = devlink_port_register(ds->devlink, &dp->devlink_port, dp->index);
 266         if (err)
 267                 return err;
 268
 269         switch (dp->type) {
 270         case DSA_PORT_TYPE_UNUSED:
 271                 break;
 272         case DSA_PORT_TYPE_CPU:
 273         case DSA_PORT_TYPE_DSA:
 274                 err = dsa_port_fixed_link_register_of(dp);
 275                 if (err) {
 276                         dev_err(ds->dev, "failed to register fixed link for port %d.%d\n",
 277                                 ds->index, dp->index);
 278                         return err;
 279                 }
 280
 281                 break;
 282         case DSA_PORT_TYPE_USER:
 283                 err = dsa_slave_create(dp);
 284                 if (err)
 285                         dev_err(ds->dev, "failed to create slave for port %d.%d\n",
 286                                 ds->index, dp->index);
 287                 else
 288                         devlink_port_type_eth_set(&dp->devlink_port, dp->slave);
 289                 break;
 290         }
 291
 292         return 0;
 293 }
 294
 295 static void dsa_port_teardown(struct dsa_port *dp)
 296 {
 297         devlink_port_unregister(&dp->devlink_port);
 298
 299         switch (dp->type) {
 300         case DSA_PORT_TYPE_UNUSED:
 301                 break;
 302         case DSA_PORT_TYPE_CPU:
 303         case DSA_PORT_TYPE_DSA:
 304                 dsa_port_fixed_link_unregister_of(dp);
 305                 break;
 306         case DSA_PORT_TYPE_USER:
 307                 if (dp->slave) {
 308                         dsa_slave_destroy(dp->slave);
 309                         dp->slave = NULL;
 310                 }
 311                 break;
 312         }
 313 }
 314
 315 static int dsa_switch_setup(struct dsa_switch *ds)
 316 {
 317         int err;
 318
 319         /* Initialize ds->phys_mii_mask before registering the slave MDIO bus
 320          * driver and before ops->setup() has run, since the switch drivers and
 321          * the slave MDIO bus driver rely on these values for probing PHY
 322          * devices or not
 323          */
 324         ds->phys_mii_mask |= dsa_user_ports(ds);
 325
 326         /* Add the switch to devlink before calling setup, so that setup can
 327          * add dpipe tables
 328          */
 329         ds->devlink = devlink_alloc(&dsa_devlink_ops, 0);
 330         if (!ds->devlink)
 331                 return -ENOMEM;
 332
 333         err = devlink_register(ds->devlink, ds->dev);
 334         if (err)
 335                 return err;
 336
 337         err = ds->ops->setup(ds);
 338         if (err < 0)
 339                 return err;
 340
 341         err = dsa_switch_register_notifier(ds);
 342         if (err)
 343                 return err;
 344
 345         if (!ds->slave_mii_bus && ds->ops->phy_read) {
 346                 ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
 347                 if (!ds->slave_mii_bus)
 348                         return -ENOMEM;
 349
 350                 dsa_slave_mii_bus_init(ds);
 351
 352                 err = mdiobus_register(ds->slave_mii_bus);
 353                 if (err < 0)
 354                         return err;
 355         }
 356
 357         return 0;
 358 }
 359
 360 static void dsa_switch_teardown(struct dsa_switch *ds)
 361 {
 362         if (ds->slave_mii_bus && ds->ops->phy_read)
 363                 mdiobus_unregister(ds->slave_mii_bus);
 364
 365         dsa_switch_unregister_notifier(ds);
 366
 367         if (ds->devlink) {
 368                 devlink_unregister(ds->devlink);
 369                 devlink_free(ds->devlink);
 370                 ds->devlink = NULL;
 371         }
 372
 373 }
 374
 375 static int dsa_tree_setup_switches(struct dsa_switch_tree *dst)
 376 {
 377         struct dsa_switch *ds;
 378         struct dsa_port *dp;
 379         int device, port;
 380         int err;
 381
 382         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 383                 ds = dst->ds[device];
 384                 if (!ds)
 385                         continue;
 386
 387                 err = dsa_switch_setup(ds);
 388                 if (err)
 389                         return err;
 390
 391                 for (port = 0; port < ds->num_ports; port++) {
 392                         dp = &ds->ports[port];
 393
 394                         err = dsa_port_setup(dp);
 395                         if (err)
 396                                 return err;
 397                 }
 398         }
 399
 400         return 0;
 401 }
 402
 403 static void dsa_tree_teardown_switches(struct dsa_switch_tree *dst)
 404 {
 405         struct dsa_switch *ds;
 406         struct dsa_port *dp;
 407         int device, port;
 408
 409         for (device = 0; device < DSA_MAX_SWITCHES; device++) {
 410                 ds = dst->ds[device];
 411                 if (!ds)
 412                         continue;
 413
 414                 for (port = 0; port < ds->num_ports; port++) {
 415                         dp = &ds->ports[port];
 416
 417                         dsa_port_teardown(dp);
 418                 }
 419
 420                 dsa_switch_teardown(ds);
 421         }
 422 }
 423
 424 static int dsa_tree_setup_master(struct dsa_switch_tree *dst)
 425 {
 426         struct dsa_port *cpu_dp = dst->cpu_dp;
 427         struct net_device *master = cpu_dp->master;
 428
 429         /* DSA currently supports a single pair of CPU port and master device */
 430         return dsa_master_setup(master, cpu_dp);
 431 }
 432
 433 static void dsa_tree_teardown_master(struct dsa_switch_tree *dst)
 434 {
 435         struct dsa_port *cpu_dp = dst->cpu_dp;
 436         struct net_device *master = cpu_dp->master;
 437
 438         return dsa_master_teardown(master);
 439 }
 440
 441 static int dsa_tree_setup(struct dsa_switch_tree *dst)
 442 {
 443         bool complete;
 444         int err;
 445
 446         if (dst->setup) {
 447                 pr_err("DSA: tree %d already setup! Disjoint trees?\n",
 448                        dst->index);
 449                 return -EEXIST;
 450         }
 451
 452         complete = dsa_tree_setup_routing_table(dst);
 453         if (!complete)
 454                 return 0;
 455
 456         err = dsa_tree_setup_default_cpu(dst);
 457         if (err)
 458                 return err;
 459
 460         err = dsa_tree_setup_switches(dst);
 461         if (err)
 462                 return err;
 463
 464         err = dsa_tree_setup_master(dst);
 465         if (err)
 466                 return err;
 467
 468         dst->setup = true;
 469
 470         pr_info("DSA: tree %d setup\n", dst->index);
 471
 472         return 0;
 473 }
 474
 475 static void dsa_tree_teardown(struct dsa_switch_tree *dst)
 476 {
 477         if (!dst->setup)
 478                 return;
 479
 480         dsa_tree_teardown_master(dst);
 481
 482         dsa_tree_teardown_switches(dst);
 483
 484         dsa_tree_teardown_default_cpu(dst);
 485
 486         pr_info("DSA: tree %d torn down\n", dst->index);
 487
 488         dst->setup = false;
 489 }
 490
 491 static void dsa_tree_remove_switch(struct dsa_switch_tree *dst,
 492                                    unsigned int index)
 493 {
 494         dsa_tree_teardown(dst);
 495
 496         dst->ds[index] = NULL;
 497         dsa_tree_put(dst);
 498 }
 499
 500 static int dsa_tree_add_switch(struct dsa_switch_tree *dst,
 501                                struct dsa_switch *ds)
 502 {
 503         unsigned int index = ds->index;
 504         int err;
 505
 506         if (dst->ds[index])
 507                 return -EBUSY;
 508
 509         dsa_tree_get(dst);
 510         dst->ds[index] = ds;
 511
 512         err = dsa_tree_setup(dst);
 513         if (err)
 514                 dsa_tree_remove_switch(dst, index);
 515
 516         return err;
 517 }
 518
 519 static int dsa_port_parse_user(struct dsa_port *dp, const char *name)
 520 {
 521         if (!name)
 522                 name = "eth%d";
 523
 524         dp->type = DSA_PORT_TYPE_USER;
 525         dp->name = name;
 526
 527         return 0;
 528 }
 529
 530 static int dsa_port_parse_dsa(struct dsa_port *dp)
 531 {
 532         dp->type = DSA_PORT_TYPE_DSA;
 533
 534         return 0;
 535 }
 536
 537 static int dsa_port_parse_cpu(struct dsa_port *dp, struct net_device *master)
 538 {
 539         struct dsa_switch *ds = dp->ds;
 540         struct dsa_switch_tree *dst = ds->dst;
 541         const struct dsa_device_ops *tag_ops;
 542         enum dsa_tag_protocol tag_protocol;
 543
 544         tag_protocol = ds->ops->get_tag_protocol(ds, dp->index);
 545         tag_ops = dsa_resolve_tag_protocol(tag_protocol);
 546         if (IS_ERR(tag_ops)) {
 547                 dev_warn(ds->dev, "No tagger for this switch\n");
 548                 return PTR_ERR(tag_ops);
 549         }
 550
 551         dp->type = DSA_PORT_TYPE_CPU;
 552         dp->rcv = tag_ops->rcv;
 553         dp->tag_ops = tag_ops;
 554         dp->master = master;
 555         dp->dst = dst;
 556
 557         return 0;
 558 }
 559
 560 static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 561 {
 562         struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
 563         const char *name = of_get_property(dn, "label", NULL);
 564         bool link = of_property_read_bool(dn, "link");
 565
 566         dp->dn = dn;
 567
 568         if (ethernet) {
 569                 struct net_device *master;
 570
 571                 master = of_find_net_device_by_node(ethernet);
 572                 if (!master)
 573                         return -EPROBE_DEFER;
 574
 575                 return dsa_port_parse_cpu(dp, master);
 576         }
 577
 578         if (link)
 579                 return dsa_port_parse_dsa(dp);
 580
 581         return dsa_port_parse_user(dp, name);
 582 }
 583
 584 static int dsa_switch_parse_ports_of(struct dsa_switch *ds,
 585                                      struct device_node *dn)
 586 {
 587         struct device_node *ports, *port;
 588         struct dsa_port *dp;
 589         u32 reg;
 590         int err;
 591
 592         ports = of_get_child_by_name(dn, "ports");
 593         if (!ports) {
 594                 dev_err(ds->dev, "no ports child node found\n");
 595                 return -EINVAL;
 596         }
 597
 598         for_each_available_child_of_node(ports, port) {
 599                 err = of_property_read_u32(port, "reg", &reg);
 600                 if (err)
 601                         return err;
 602
 603                 if (reg >= ds->num_ports)
 604                         return -EINVAL;
 605
 606                 dp = &ds->ports[reg];
 607
 608                 err = dsa_port_parse_of(dp, port);
 609                 if (err)
 610                         return err;
 611         }
 612
 613         return 0;
 614 }
 615
 616 static int dsa_switch_parse_member_of(struct dsa_switch *ds,
 617                                       struct device_node *dn)
 618 {
 619         u32 m[2] = { 0, 0 };
 620         int sz;
 621
 622         /* Don't error out if this optional property isn't found */
 623         sz = of_property_read_variable_u32_array(dn, "dsa,member", m, 2, 2);
 624         if (sz < 0 && sz != -EINVAL)
 625                 return sz;
 626
 627         ds->index = m[1];
 628         if (ds->index >= DSA_MAX_SWITCHES)
 629                 return -EINVAL;
 630
 631         ds->dst = dsa_tree_touch(m[0]);
 632         if (!ds->dst)
 633                 return -ENOMEM;
 634
 635         return 0;
 636 }
 637
 638 static int dsa_switch_parse_of(struct dsa_switch *ds, struct device_node *dn)
 639 {
 640         int err;
 641
 642         err = dsa_switch_parse_member_of(ds, dn);
 643         if (err)
 644                 return err;
 645
 646         return dsa_switch_parse_ports_of(ds, dn);
 647 }
 648
 649 static int dsa_port_parse(struct dsa_port *dp, const char *name,
 650                           struct device *dev)
 651 {
 652         if (!strcmp(name, "cpu")) {
 653                 struct net_device *master;
 654
 655                 master = dsa_dev_to_net_device(dev);
 656                 if (!master)
 657                         return -EPROBE_DEFER;
 658
 659                 dev_put(master);
 660
 661                 return dsa_port_parse_cpu(dp, master);
 662         }
 663
 664         if (!strcmp(name, "dsa"))
 665                 return dsa_port_parse_dsa(dp);
 666
 667         return dsa_port_parse_user(dp, name);
 668 }
 669
 670 static int dsa_switch_parse_ports(struct dsa_switch *ds,
 671                                   struct dsa_chip_data *cd)
 672 {
 673         bool valid_name_found = false;
 674         struct dsa_port *dp;
 675         struct device *dev;
 676         const char *name;
 677         unsigned int i;
 678         int err;
 679
 680         for (i = 0; i < DSA_MAX_PORTS; i++) {
 681                 name = cd->port_names[i];
 682                 dev = cd->netdev[i];
 683                 dp = &ds->ports[i];
 684
 685                 if (!name)
 686                         continue;
 687
 688                 err = dsa_port_parse(dp, name, dev);
 689                 if (err)
 690                         return err;
 691
 692                 valid_name_found = true;
 693         }
 694
 695         if (!valid_name_found && i == DSA_MAX_PORTS)
 696                 return -EINVAL;
 697
 698         return 0;
 699 }
 700
 701 static int dsa_switch_parse(struct dsa_switch *ds, struct dsa_chip_data *cd)
 702 {
 703         ds->cd = cd;
 704
 705         /* We don't support interconnected switches nor multiple trees via
 706          * platform data, so this is the unique switch of the tree.
 707          */
 708         ds->index = 0;
 709         ds->dst = dsa_tree_touch(0);
 710         if (!ds->dst)
 711                 return -ENOMEM;
 712
 713         return dsa_switch_parse_ports(ds, cd);
 714 }
 715
 716 static int dsa_switch_add(struct dsa_switch *ds)
 717 {
 718         struct dsa_switch_tree *dst = ds->dst;
 719
 720         return dsa_tree_add_switch(dst, ds);
 721 }
 722
 723 static int dsa_switch_probe(struct dsa_switch *ds)
 724 {
 725         struct dsa_chip_data *pdata = ds->dev->platform_data;
 726         struct device_node *np = ds->dev->of_node;
 727         int err;
 728
 729         if (np)
 730                 err = dsa_switch_parse_of(ds, np);
 731         else if (pdata)
 732                 err = dsa_switch_parse(ds, pdata);
 733         else
 734                 err = -ENODEV;
 735
 736         if (err)
 737                 return err;
 738
 739         return dsa_switch_add(ds);
 740 }
 741
 742 struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n)
 743 {
 744         size_t size = sizeof(struct dsa_switch) + n * sizeof(struct dsa_port);
 745         struct dsa_switch *ds;
 746         int i;
 747
 748         ds = devm_kzalloc(dev, size, GFP_KERNEL);
 749         if (!ds)
 750                 return NULL;
 751
 752         ds->dev = dev;
 753         ds->num_ports = n;
 754
 755         for (i = 0; i < ds->num_ports; ++i) {
 756                 ds->ports[i].index = i;
 757                 ds->ports[i].ds = ds;
 758         }
 759
 760         return ds;
 761 }
 762 EXPORT_SYMBOL_GPL(dsa_switch_alloc);
 763
 764 int dsa_register_switch(struct dsa_switch *ds)
 765 {
 766         int err;
 767
 768         mutex_lock(&dsa2_mutex);
 769         err = dsa_switch_probe(ds);
 770         dsa_tree_put(ds->dst);
 771         mutex_unlock(&dsa2_mutex);
 772
 773         return err;
 774 }
 775 EXPORT_SYMBOL_GPL(dsa_register_switch);
 776
 777 static void dsa_switch_remove(struct dsa_switch *ds)
 778 {
 779         struct dsa_switch_tree *dst = ds->dst;
 780         unsigned int index = ds->index;
 781
 782         dsa_tree_remove_switch(dst, index);
 783 }
 784
 785 void dsa_unregister_switch(struct dsa_switch *ds)
 786 {
 787         mutex_lock(&dsa2_mutex);
 788         dsa_switch_remove(ds);
 789         mutex_unlock(&dsa2_mutex);
 790 }
 791 EXPORT_SYMBOL_GPL(dsa_unregister_switch);