root/drivers/net/phy/mdio_bus.c

DEFINITIONS

1. mdiobus_register_gpiod
2. mdiobus_register_reset
3. mdiobus_register_device
4. mdiobus_unregister_device
5. mdiobus_get_phy
6. mdiobus_is_registered_device
7. mdiobus_alloc_size
8. _devm_mdiobus_free
9. devm_mdiobus_match
10. devm_mdiobus_alloc_size
11. devm_mdiobus_free
12. mdiobus_release
13. of_mdio_find_bus
14. of_mdiobus_link_mdiodev
15. of_mdiobus_link_mdiodev
16. mdiobus_create_device
17. __mdiobus_register
18. mdiobus_unregister
19. mdiobus_free
20. mdiobus_scan
21. __mdiobus_read
22. __mdiobus_write
23. mdiobus_read_nested
24. mdiobus_read
25. mdiobus_write_nested
26. mdiobus_write
27. mdio_bus_match
28. mdio_uevent
29. mdio_bus_init
30. mdio_bus_exit

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /* MDIO Bus interface
   3  *
   4  * Author: Andy Fleming
   5  *
   6  * Copyright (c) 2004 Freescale Semiconductor, Inc.
   7  */
   8 
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10 
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/unistd.h>
  15 #include <linux/slab.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/init.h>
  18 #include <linux/delay.h>
  19 #include <linux/device.h>
  20 #include <linux/gpio.h>
  21 #include <linux/gpio/consumer.h>
  22 #include <linux/of_device.h>
  23 #include <linux/of_mdio.h>
  24 #include <linux/of_gpio.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/etherdevice.h>
  27 #include <linux/reset.h>
  28 #include <linux/skbuff.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/mm.h>
  31 #include <linux/module.h>
  32 #include <linux/mii.h>
  33 #include <linux/ethtool.h>
  34 #include <linux/phy.h>
  35 #include <linux/io.h>
  36 #include <linux/uaccess.h>
  37 
  38 #define CREATE_TRACE_POINTS
  39 #include <trace/events/mdio.h>
  40 
  41 #include "mdio-boardinfo.h"
  42 
  43 static int mdiobus_register_gpiod(struct mdio_device *mdiodev)
  44 {
  45         int error;
  46 
  47         /* Deassert the optional reset signal */
  48         mdiodev->reset_gpio = gpiod_get_optional(&mdiodev->dev,
  49                                                  "reset", GPIOD_OUT_LOW);
  50         error = PTR_ERR_OR_ZERO(mdiodev->reset_gpio);
  51         if (error)
  52                 return error;
  53 
  54         if (mdiodev->reset_gpio)
  55                 gpiod_set_consumer_name(mdiodev->reset_gpio, "PHY reset");
  56 
  57         return 0;
  58 }
  59 
  60 static int mdiobus_register_reset(struct mdio_device *mdiodev)
  61 {
  62         struct reset_control *reset = NULL;
  63 
  64         if (mdiodev->dev.of_node)
  65                 reset = of_reset_control_get_exclusive(mdiodev->dev.of_node,
  66                                                        "phy");
  67         if (IS_ERR(reset)) {
  68                 if (PTR_ERR(reset) == -ENOENT || PTR_ERR(reset) == -ENOTSUPP)
  69                         reset = NULL;
  70                 else
  71                         return PTR_ERR(reset);
  72         }
  73 
  74         mdiodev->reset_ctrl = reset;
  75 
  76         return 0;
  77 }
  78 
  79 int mdiobus_register_device(struct mdio_device *mdiodev)
  80 {
  81         int err;
  82 
  83         if (mdiodev->bus->mdio_map[mdiodev->addr])
  84                 return -EBUSY;
  85 
  86         if (mdiodev->flags & MDIO_DEVICE_FLAG_PHY) {
  87                 err = mdiobus_register_gpiod(mdiodev);
  88                 if (err)
  89                         return err;
  90 
  91                 err = mdiobus_register_reset(mdiodev);
  92                 if (err)
  93                         return err;
  94 
  95                 /* Assert the reset signal */
  96                 mdio_device_reset(mdiodev, 1);
  97         }
  98 
  99         mdiodev->bus->mdio_map[mdiodev->addr] = mdiodev;
 100 
 101         return 0;
 102 }
 103 EXPORT_SYMBOL(mdiobus_register_device);
 104 
 105 int mdiobus_unregister_device(struct mdio_device *mdiodev)
 106 {
 107         if (mdiodev->bus->mdio_map[mdiodev->addr] != mdiodev)
 108                 return -EINVAL;
 109 
 110         reset_control_put(mdiodev->reset_ctrl);
 111 
 112         mdiodev->bus->mdio_map[mdiodev->addr] = NULL;
 113 
 114         return 0;
 115 }
 116 EXPORT_SYMBOL(mdiobus_unregister_device);
 117 
 118 struct phy_device *mdiobus_get_phy(struct mii_bus *bus, int addr)
 119 {
 120         struct mdio_device *mdiodev = bus->mdio_map[addr];
 121 
 122         if (!mdiodev)
 123                 return NULL;
 124 
 125         if (!(mdiodev->flags & MDIO_DEVICE_FLAG_PHY))
 126                 return NULL;
 127 
 128         return container_of(mdiodev, struct phy_device, mdio);
 129 }
 130 EXPORT_SYMBOL(mdiobus_get_phy);
 131 
 132 bool mdiobus_is_registered_device(struct mii_bus *bus, int addr)
 133 {
 134         return bus->mdio_map[addr];
 135 }
 136 EXPORT_SYMBOL(mdiobus_is_registered_device);
 137 
 138 /**
 139  * mdiobus_alloc_size - allocate a mii_bus structure
 140  * @size: extra amount of memory to allocate for private storage.
 141  * If non-zero, then bus->priv is points to that memory.
 142  *
 143  * Description: called by a bus driver to allocate an mii_bus
 144  * structure to fill in.
 145  */
 146 struct mii_bus *mdiobus_alloc_size(size_t size)
 147 {
 148         struct mii_bus *bus;
 149         size_t aligned_size = ALIGN(sizeof(*bus), NETDEV_ALIGN);
 150         size_t alloc_size;
 151         int i;
 152 
 153         /* If we alloc extra space, it should be aligned */
 154         if (size)
 155                 alloc_size = aligned_size + size;
 156         else
 157                 alloc_size = sizeof(*bus);
 158 
 159         bus = kzalloc(alloc_size, GFP_KERNEL);
 160         if (!bus)
 161                 return NULL;
 162 
 163         bus->state = MDIOBUS_ALLOCATED;
 164         if (size)
 165                 bus->priv = (void *)bus + aligned_size;
 166 
 167         /* Initialise the interrupts to polling */
 168         for (i = 0; i < PHY_MAX_ADDR; i++)
 169                 bus->irq[i] = PHY_POLL;
 170 
 171         return bus;
 172 }
 173 EXPORT_SYMBOL(mdiobus_alloc_size);
 174 
 175 static void _devm_mdiobus_free(struct device *dev, void *res)
 176 {
 177         mdiobus_free(*(struct mii_bus **)res);
 178 }
 179 
 180 static int devm_mdiobus_match(struct device *dev, void *res, void *data)
 181 {
 182         struct mii_bus **r = res;
 183 
 184         if (WARN_ON(!r || !*r))
 185                 return 0;
 186 
 187         return *r == data;
 188 }
 189 
 190 /**
 191  * devm_mdiobus_alloc_size - Resource-managed mdiobus_alloc_size()
 192  * @dev:                Device to allocate mii_bus for
 193  * @sizeof_priv:        Space to allocate for private structure.
 194  *
 195  * Managed mdiobus_alloc_size. mii_bus allocated with this function is
 196  * automatically freed on driver detach.
 197  *
 198  * If an mii_bus allocated with this function needs to be freed separately,
 199  * devm_mdiobus_free() must be used.
 200  *
 201  * RETURNS:
 202  * Pointer to allocated mii_bus on success, NULL on failure.
 203  */
 204 struct mii_bus *devm_mdiobus_alloc_size(struct device *dev, int sizeof_priv)
 205 {
 206         struct mii_bus **ptr, *bus;
 207 
 208         ptr = devres_alloc(_devm_mdiobus_free, sizeof(*ptr), GFP_KERNEL);
 209         if (!ptr)
 210                 return NULL;
 211 
 212         /* use raw alloc_dr for kmalloc caller tracing */
 213         bus = mdiobus_alloc_size(sizeof_priv);
 214         if (bus) {
 215                 *ptr = bus;
 216                 devres_add(dev, ptr);
 217         } else {
 218                 devres_free(ptr);
 219         }
 220 
 221         return bus;
 222 }
 223 EXPORT_SYMBOL_GPL(devm_mdiobus_alloc_size);
 224 
 225 /**
 226  * devm_mdiobus_free - Resource-managed mdiobus_free()
 227  * @dev:                Device this mii_bus belongs to
 228  * @bus:                the mii_bus associated with the device
 229  *
 230  * Free mii_bus allocated with devm_mdiobus_alloc_size().
 231  */
 232 void devm_mdiobus_free(struct device *dev, struct mii_bus *bus)
 233 {
 234         int rc;
 235 
 236         rc = devres_release(dev, _devm_mdiobus_free,
 237                             devm_mdiobus_match, bus);
 238         WARN_ON(rc);
 239 }
 240 EXPORT_SYMBOL_GPL(devm_mdiobus_free);
 241 
 242 /**
 243  * mdiobus_release - mii_bus device release callback
 244  * @d: the target struct device that contains the mii_bus
 245  *
 246  * Description: called when the last reference to an mii_bus is
 247  * dropped, to free the underlying memory.
 248  */
 249 static void mdiobus_release(struct device *d)
 250 {
 251         struct mii_bus *bus = to_mii_bus(d);
 252         BUG_ON(bus->state != MDIOBUS_RELEASED &&
 253                /* for compatibility with error handling in drivers */
 254                bus->state != MDIOBUS_ALLOCATED);
 255         kfree(bus);
 256 }
 257 
 258 static struct class mdio_bus_class = {
 259         .name           = "mdio_bus",
 260         .dev_release    = mdiobus_release,
 261 };
 262 
 263 #if IS_ENABLED(CONFIG_OF_MDIO)
 264 /**
 265  * of_mdio_find_bus - Given an mii_bus node, find the mii_bus.
 266  * @mdio_bus_np: Pointer to the mii_bus.
 267  *
 268  * Returns a reference to the mii_bus, or NULL if none found.  The
 269  * embedded struct device will have its reference count incremented,
 270  * and this must be put once the bus is finished with.
 271  *
 272  * Because the association of a device_node and mii_bus is made via
 273  * of_mdiobus_register(), the mii_bus cannot be found before it is
 274  * registered with of_mdiobus_register().
 275  *
 276  */
 277 struct mii_bus *of_mdio_find_bus(struct device_node *mdio_bus_np)
 278 {
 279         struct device *d;
 280 
 281         if (!mdio_bus_np)
 282                 return NULL;
 283 
 284         d = class_find_device_by_of_node(&mdio_bus_class, mdio_bus_np);
 285         return d ? to_mii_bus(d) : NULL;
 286 }
 287 EXPORT_SYMBOL(of_mdio_find_bus);
 288 
 289 /* Walk the list of subnodes of a mdio bus and look for a node that
 290  * matches the mdio device's address with its 'reg' property. If
 291  * found, set the of_node pointer for the mdio device. This allows
 292  * auto-probed phy devices to be supplied with information passed in
 293  * via DT.
 294  */
 295 static void of_mdiobus_link_mdiodev(struct mii_bus *bus,
 296                                     struct mdio_device *mdiodev)
 297 {
 298         struct device *dev = &mdiodev->dev;
 299         struct device_node *child;
 300 
 301         if (dev->of_node || !bus->dev.of_node)
 302                 return;
 303 
 304         for_each_available_child_of_node(bus->dev.of_node, child) {
 305                 int addr;
 306 
 307                 addr = of_mdio_parse_addr(dev, child);
 308                 if (addr < 0)
 309                         continue;
 310 
 311                 if (addr == mdiodev->addr) {
 312                         dev->of_node = child;
 313                         dev->fwnode = of_fwnode_handle(child);
 314                         return;
 315                 }
 316         }
 317 }
 318 #else /* !IS_ENABLED(CONFIG_OF_MDIO) */
 319 static inline void of_mdiobus_link_mdiodev(struct mii_bus *mdio,
 320                                            struct mdio_device *mdiodev)
 321 {
 322 }
 323 #endif
 324 
 325 /**
 326  * mdiobus_create_device_from_board_info - create a full MDIO device given
 327  * a mdio_board_info structure
 328  * @bus: MDIO bus to create the devices on
 329  * @bi: mdio_board_info structure describing the devices
 330  *
 331  * Returns 0 on success or < 0 on error.
 332  */
 333 static int mdiobus_create_device(struct mii_bus *bus,
 334                                  struct mdio_board_info *bi)
 335 {
 336         struct mdio_device *mdiodev;
 337         int ret = 0;
 338 
 339         mdiodev = mdio_device_create(bus, bi->mdio_addr);
 340         if (IS_ERR(mdiodev))
 341                 return -ENODEV;
 342 
 343         strncpy(mdiodev->modalias, bi->modalias,
 344                 sizeof(mdiodev->modalias));
 345         mdiodev->bus_match = mdio_device_bus_match;
 346         mdiodev->dev.platform_data = (void *)bi->platform_data;
 347 
 348         ret = mdio_device_register(mdiodev);
 349         if (ret)
 350                 mdio_device_free(mdiodev);
 351 
 352         return ret;
 353 }
 354 
 355 /**
 356  * __mdiobus_register - bring up all the PHYs on a given bus and attach them to bus
 357  * @bus: target mii_bus
 358  * @owner: module containing bus accessor functions
 359  *
 360  * Description: Called by a bus driver to bring up all the PHYs
 361  *   on a given bus, and attach them to the bus. Drivers should use
 362  *   mdiobus_register() rather than __mdiobus_register() unless they
 363  *   need to pass a specific owner module. MDIO devices which are not
 364  *   PHYs will not be brought up by this function. They are expected to
 365  *   to be explicitly listed in DT and instantiated by of_mdiobus_register().
 366  *
 367  * Returns 0 on success or < 0 on error.
 368  */
 369 int __mdiobus_register(struct mii_bus *bus, struct module *owner)
 370 {
 371         struct mdio_device *mdiodev;
 372         int i, err;
 373         struct gpio_desc *gpiod;
 374 
 375         if (NULL == bus || NULL == bus->name ||
 376             NULL == bus->read || NULL == bus->write)
 377                 return -EINVAL;
 378 
 379         BUG_ON(bus->state != MDIOBUS_ALLOCATED &&
 380                bus->state != MDIOBUS_UNREGISTERED);
 381 
 382         bus->owner = owner;
 383         bus->dev.parent = bus->parent;
 384         bus->dev.class = &mdio_bus_class;
 385         bus->dev.groups = NULL;
 386         dev_set_name(&bus->dev, "%s", bus->id);
 387 
 388         err = device_register(&bus->dev);
 389         if (err) {
 390                 pr_err("mii_bus %s failed to register\n", bus->id);
 391                 return -EINVAL;
 392         }
 393 
 394         mutex_init(&bus->mdio_lock);
 395 
 396         /* de-assert bus level PHY GPIO reset */
 397         gpiod = devm_gpiod_get_optional(&bus->dev, "reset", GPIOD_OUT_LOW);
 398         if (IS_ERR(gpiod)) {
 399                 dev_err(&bus->dev, "mii_bus %s couldn't get reset GPIO\n",
 400                         bus->id);
 401                 device_del(&bus->dev);
 402                 return PTR_ERR(gpiod);
 403         } else  if (gpiod) {
 404                 bus->reset_gpiod = gpiod;
 405 
 406                 gpiod_set_value_cansleep(gpiod, 1);
 407                 udelay(bus->reset_delay_us);
 408                 gpiod_set_value_cansleep(gpiod, 0);
 409         }
 410 
 411         if (bus->reset)
 412                 bus->reset(bus);
 413 
 414         for (i = 0; i < PHY_MAX_ADDR; i++) {
 415                 if ((bus->phy_mask & (1 << i)) == 0) {
 416                         struct phy_device *phydev;
 417 
 418                         phydev = mdiobus_scan(bus, i);
 419                         if (IS_ERR(phydev) && (PTR_ERR(phydev) != -ENODEV)) {
 420                                 err = PTR_ERR(phydev);
 421                                 goto error;
 422                         }
 423                 }
 424         }
 425 
 426         mdiobus_setup_mdiodev_from_board_info(bus, mdiobus_create_device);
 427 
 428         bus->state = MDIOBUS_REGISTERED;
 429         pr_info("%s: probed\n", bus->name);
 430         return 0;
 431 
 432 error:
 433         while (--i >= 0) {
 434                 mdiodev = bus->mdio_map[i];
 435                 if (!mdiodev)
 436                         continue;
 437 
 438                 mdiodev->device_remove(mdiodev);
 439                 mdiodev->device_free(mdiodev);
 440         }
 441 
 442         /* Put PHYs in RESET to save power */
 443         if (bus->reset_gpiod)
 444                 gpiod_set_value_cansleep(bus->reset_gpiod, 1);
 445 
 446         device_del(&bus->dev);
 447         return err;
 448 }
 449 EXPORT_SYMBOL(__mdiobus_register);
 450 
 451 void mdiobus_unregister(struct mii_bus *bus)
 452 {
 453         struct mdio_device *mdiodev;
 454         int i;
 455 
 456         BUG_ON(bus->state != MDIOBUS_REGISTERED);
 457         bus->state = MDIOBUS_UNREGISTERED;
 458 
 459         for (i = 0; i < PHY_MAX_ADDR; i++) {
 460                 mdiodev = bus->mdio_map[i];
 461                 if (!mdiodev)
 462                         continue;
 463 
 464                 if (mdiodev->reset_gpio)
 465                         gpiod_put(mdiodev->reset_gpio);
 466 
 467                 mdiodev->device_remove(mdiodev);
 468                 mdiodev->device_free(mdiodev);
 469         }
 470 
 471         /* Put PHYs in RESET to save power */
 472         if (bus->reset_gpiod)
 473                 gpiod_set_value_cansleep(bus->reset_gpiod, 1);
 474 
 475         device_del(&bus->dev);
 476 }
 477 EXPORT_SYMBOL(mdiobus_unregister);
 478 
 479 /**
 480  * mdiobus_free - free a struct mii_bus
 481  * @bus: mii_bus to free
 482  *
 483  * This function releases the reference to the underlying device
 484  * object in the mii_bus.  If this is the last reference, the mii_bus
 485  * will be freed.
 486  */
 487 void mdiobus_free(struct mii_bus *bus)
 488 {
 489         /* For compatibility with error handling in drivers. */
 490         if (bus->state == MDIOBUS_ALLOCATED) {
 491                 kfree(bus);
 492                 return;
 493         }
 494 
 495         BUG_ON(bus->state != MDIOBUS_UNREGISTERED);
 496         bus->state = MDIOBUS_RELEASED;
 497 
 498         put_device(&bus->dev);
 499 }
 500 EXPORT_SYMBOL(mdiobus_free);
 501 
 502 /**
 503  * mdiobus_scan - scan a bus for MDIO devices.
 504  * @bus: mii_bus to scan
 505  * @addr: address on bus to scan
 506  *
 507  * This function scans the MDIO bus, looking for devices which can be
 508  * identified using a vendor/product ID in registers 2 and 3. Not all
 509  * MDIO devices have such registers, but PHY devices typically
 510  * do. Hence this function assumes anything found is a PHY, or can be
 511  * treated as a PHY. Other MDIO devices, such as switches, will
 512  * probably not be found during the scan.
 513  */
 514 struct phy_device *mdiobus_scan(struct mii_bus *bus, int addr)
 515 {
 516         struct phy_device *phydev;
 517         int err;
 518 
 519         phydev = get_phy_device(bus, addr, false);
 520         if (IS_ERR(phydev))
 521                 return phydev;
 522 
 523         /*
 524          * For DT, see if the auto-probed phy has a correspoding child
 525          * in the bus node, and set the of_node pointer in this case.
 526          */
 527         of_mdiobus_link_mdiodev(bus, &phydev->mdio);
 528 
 529         err = phy_device_register(phydev);
 530         if (err) {
 531                 phy_device_free(phydev);
 532                 return ERR_PTR(-ENODEV);
 533         }
 534 
 535         return phydev;
 536 }
 537 EXPORT_SYMBOL(mdiobus_scan);
 538 
 539 /**
 540  * __mdiobus_read - Unlocked version of the mdiobus_read function
 541  * @bus: the mii_bus struct
 542  * @addr: the phy address
 543  * @regnum: register number to read
 544  *
 545  * Read a MDIO bus register. Caller must hold the mdio bus lock.
 546  *
 547  * NOTE: MUST NOT be called from interrupt context.
 548  */
 549 int __mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 550 {
 551         int retval;
 552 
 553         WARN_ON_ONCE(!mutex_is_locked(&bus->mdio_lock));
 554 
 555         retval = bus->read(bus, addr, regnum);
 556 
 557         trace_mdio_access(bus, 1, addr, regnum, retval, retval);
 558 
 559         return retval;
 560 }
 561 EXPORT_SYMBOL(__mdiobus_read);
 562 
 563 /**
 564  * __mdiobus_write - Unlocked version of the mdiobus_write function
 565  * @bus: the mii_bus struct
 566  * @addr: the phy address
 567  * @regnum: register number to write
 568  * @val: value to write to @regnum
 569  *
 570  * Write a MDIO bus register. Caller must hold the mdio bus lock.
 571  *
 572  * NOTE: MUST NOT be called from interrupt context.
 573  */
 574 int __mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 575 {
 576         int err;
 577 
 578         WARN_ON_ONCE(!mutex_is_locked(&bus->mdio_lock));
 579 
 580         err = bus->write(bus, addr, regnum, val);
 581 
 582         trace_mdio_access(bus, 0, addr, regnum, val, err);
 583 
 584         return err;
 585 }
 586 EXPORT_SYMBOL(__mdiobus_write);
 587 
 588 /**
 589  * mdiobus_read_nested - Nested version of the mdiobus_read function
 590  * @bus: the mii_bus struct
 591  * @addr: the phy address
 592  * @regnum: register number to read
 593  *
 594  * In case of nested MDIO bus access avoid lockdep false positives by
 595  * using mutex_lock_nested().
 596  *
 597  * NOTE: MUST NOT be called from interrupt context,
 598  * because the bus read/write functions may wait for an interrupt
 599  * to conclude the operation.
 600  */
 601 int mdiobus_read_nested(struct mii_bus *bus, int addr, u32 regnum)
 602 {
 603         int retval;
 604 
 605         BUG_ON(in_interrupt());
 606 
 607         mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
 608         retval = __mdiobus_read(bus, addr, regnum);
 609         mutex_unlock(&bus->mdio_lock);
 610 
 611         return retval;
 612 }
 613 EXPORT_SYMBOL(mdiobus_read_nested);
 614 
 615 /**
 616  * mdiobus_read - Convenience function for reading a given MII mgmt register
 617  * @bus: the mii_bus struct
 618  * @addr: the phy address
 619  * @regnum: register number to read
 620  *
 621  * NOTE: MUST NOT be called from interrupt context,
 622  * because the bus read/write functions may wait for an interrupt
 623  * to conclude the operation.
 624  */
 625 int mdiobus_read(struct mii_bus *bus, int addr, u32 regnum)
 626 {
 627         int retval;
 628 
 629         BUG_ON(in_interrupt());
 630 
 631         mutex_lock(&bus->mdio_lock);
 632         retval = __mdiobus_read(bus, addr, regnum);
 633         mutex_unlock(&bus->mdio_lock);
 634 
 635         return retval;
 636 }
 637 EXPORT_SYMBOL(mdiobus_read);
 638 
 639 /**
 640  * mdiobus_write_nested - Nested version of the mdiobus_write function
 641  * @bus: the mii_bus struct
 642  * @addr: the phy address
 643  * @regnum: register number to write
 644  * @val: value to write to @regnum
 645  *
 646  * In case of nested MDIO bus access avoid lockdep false positives by
 647  * using mutex_lock_nested().
 648  *
 649  * NOTE: MUST NOT be called from interrupt context,
 650  * because the bus read/write functions may wait for an interrupt
 651  * to conclude the operation.
 652  */
 653 int mdiobus_write_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 654 {
 655         int err;
 656 
 657         BUG_ON(in_interrupt());
 658 
 659         mutex_lock_nested(&bus->mdio_lock, MDIO_MUTEX_NESTED);
 660         err = __mdiobus_write(bus, addr, regnum, val);
 661         mutex_unlock(&bus->mdio_lock);
 662 
 663         return err;
 664 }
 665 EXPORT_SYMBOL(mdiobus_write_nested);
 666 
 667 /**
 668  * mdiobus_write - Convenience function for writing a given MII mgmt register
 669  * @bus: the mii_bus struct
 670  * @addr: the phy address
 671  * @regnum: register number to write
 672  * @val: value to write to @regnum
 673  *
 674  * NOTE: MUST NOT be called from interrupt context,
 675  * because the bus read/write functions may wait for an interrupt
 676  * to conclude the operation.
 677  */
 678 int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val)
 679 {
 680         int err;
 681 
 682         BUG_ON(in_interrupt());
 683 
 684         mutex_lock(&bus->mdio_lock);
 685         err = __mdiobus_write(bus, addr, regnum, val);
 686         mutex_unlock(&bus->mdio_lock);
 687 
 688         return err;
 689 }
 690 EXPORT_SYMBOL(mdiobus_write);
 691 
 692 /**
 693  * mdio_bus_match - determine if given MDIO driver supports the given
 694  *                  MDIO device
 695  * @dev: target MDIO device
 696  * @drv: given MDIO driver
 697  *
 698  * Description: Given a MDIO device, and a MDIO driver, return 1 if
 699  *   the driver supports the device.  Otherwise, return 0. This may
 700  *   require calling the devices own match function, since different classes
 701  *   of MDIO devices have different match criteria.
 702  */
 703 static int mdio_bus_match(struct device *dev, struct device_driver *drv)
 704 {
 705         struct mdio_device *mdio = to_mdio_device(dev);
 706 
 707         if (of_driver_match_device(dev, drv))
 708                 return 1;
 709 
 710         if (mdio->bus_match)
 711                 return mdio->bus_match(dev, drv);
 712 
 713         return 0;
 714 }
 715 
 716 static int mdio_uevent(struct device *dev, struct kobj_uevent_env *env)
 717 {
 718         int rc;
 719 
 720         /* Some devices have extra OF data and an OF-style MODALIAS */
 721         rc = of_device_uevent_modalias(dev, env);
 722         if (rc != -ENODEV)
 723                 return rc;
 724 
 725         return 0;
 726 }
 727 
 728 struct bus_type mdio_bus_type = {
 729         .name           = "mdio_bus",
 730         .match          = mdio_bus_match,
 731         .uevent         = mdio_uevent,
 732 };
 733 EXPORT_SYMBOL(mdio_bus_type);
 734 
 735 int __init mdio_bus_init(void)
 736 {
 737         int ret;
 738 
 739         ret = class_register(&mdio_bus_class);
 740         if (!ret) {
 741                 ret = bus_register(&mdio_bus_type);
 742                 if (ret)
 743                         class_unregister(&mdio_bus_class);
 744         }
 745 
 746         return ret;
 747 }
 748 EXPORT_SYMBOL_GPL(mdio_bus_init);
 749 
 750 #if IS_ENABLED(CONFIG_PHYLIB)
 751 void mdio_bus_exit(void)
 752 {
 753         class_unregister(&mdio_bus_class);
 754         bus_unregister(&mdio_bus_type);
 755 }
 756 EXPORT_SYMBOL_GPL(mdio_bus_exit);
 757 #else
 758 module_init(mdio_bus_init);
 759 /* no module_exit, intentional */
 760 MODULE_LICENSE("GPL");
 761 MODULE_DESCRIPTION("MDIO bus/device layer");
 762 #endif