1// SPDX-License-Identifier: GPL-2.0 2/* 3 * I2C Address Translator 4 * 5 * Copyright (c) 2019,2022 Luca Ceresoli <luca@lucaceresoli.net> 6 * Copyright (c) 2022,2023 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> 7 * 8 * Originally based on i2c-mux.c 9 */ 10 11#include <linux/fwnode.h> 12#include <linux/i2c-atr.h> 13#include <linux/i2c.h> 14#include <linux/kernel.h> 15#include <linux/module.h> 16#include <linux/mutex.h> 17#include <linux/slab.h> 18#include <linux/spinlock.h> 19 20#define ATR_MAX_ADAPTERS 100 /* Just a sanity limit */ 21#define ATR_MAX_SYMLINK_LEN 11 /* Longest name is 10 chars: "channel-99" */ 22 23/** 24 * struct i2c_atr_alias_pair - Holds the alias assigned to a client. 25 * @node: List node 26 * @client: Pointer to the client on the child bus 27 * @alias: I2C alias address assigned by the driver. 28 * This is the address that will be used to issue I2C transactions 29 * on the parent (physical) bus. 30 */ 31struct i2c_atr_alias_pair { 32 struct list_head node; 33 const struct i2c_client *client; 34 u16 alias; 35}; 36 37/** 38 * struct i2c_atr_chan - Data for a channel. 39 * @adap: The &struct i2c_adapter for the channel 40 * @atr: The parent I2C ATR 41 * @chan_id: The ID of this channel 42 * @alias_list: List of @struct i2c_atr_alias_pair containing the 43 * assigned aliases 44 * @orig_addrs_lock: Mutex protecting @orig_addrs 45 * @orig_addrs: Buffer used to store the original addresses during transmit 46 * @orig_addrs_size: Size of @orig_addrs 47 */ 48struct i2c_atr_chan { 49 struct i2c_adapter adap; 50 struct i2c_atr *atr; 51 u32 chan_id; 52 53 struct list_head alias_list; 54 55 /* Lock orig_addrs during xfer */ 56 struct mutex orig_addrs_lock; 57 u16 *orig_addrs; 58 unsigned int orig_addrs_size; 59}; 60 61/** 62 * struct i2c_atr - The I2C ATR instance 63 * @parent: The parent &struct i2c_adapter 64 * @dev: The device that owns the I2C ATR instance 65 * @ops: &struct i2c_atr_ops 66 * @priv: Private driver data, set with i2c_atr_set_driver_data() 67 * @algo: The &struct i2c_algorithm for adapters 68 * @lock: Lock for the I2C bus segment (see &struct i2c_lock_operations) 69 * @max_adapters: Maximum number of adapters this I2C ATR can have 70 * @num_aliases: Number of aliases in the aliases array 71 * @aliases: The aliases array 72 * @alias_mask_lock: Lock protecting alias_use_mask 73 * @alias_use_mask: Bitmask for used aliases in aliases array 74 * @i2c_nb: Notifier for remote client add & del events 75 * @adapter: Array of adapters 76 */ 77struct i2c_atr { 78 struct i2c_adapter *parent; 79 struct device *dev; 80 const struct i2c_atr_ops *ops; 81 82 void *priv; 83 84 struct i2c_algorithm algo; 85 /* lock for the I2C bus segment (see struct i2c_lock_operations) */ 86 struct mutex lock; 87 int max_adapters; 88 89 size_t num_aliases; 90 const u16 *aliases; 91 /* Protects alias_use_mask */ 92 spinlock_t alias_mask_lock; 93 unsigned long *alias_use_mask; 94 95 struct notifier_block i2c_nb; 96 97 struct i2c_adapter *adapter[] __counted_by(max_adapters); 98}; 99 100static struct i2c_atr_alias_pair * 101i2c_atr_find_mapping_by_client(const struct list_head *list, 102 const struct i2c_client *client) 103{ 104 struct i2c_atr_alias_pair *c2a; 105 106 list_for_each_entry(c2a, list, node) { 107 if (c2a->client == client) 108 return c2a; 109 } 110 111 return NULL; 112} 113 114static struct i2c_atr_alias_pair * 115i2c_atr_find_mapping_by_addr(const struct list_head *list, u16 phys_addr) 116{ 117 struct i2c_atr_alias_pair *c2a; 118 119 list_for_each_entry(c2a, list, node) { 120 if (c2a->client->addr == phys_addr) 121 return c2a; 122 } 123 124 return NULL; 125} 126 127/* 128 * Replace all message addresses with their aliases, saving the original 129 * addresses. 130 * 131 * This function is internal for use in i2c_atr_master_xfer(). It must be 132 * followed by i2c_atr_unmap_msgs() to restore the original addresses. 133 */ 134static int i2c_atr_map_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs, 135 int num) 136{ 137 struct i2c_atr *atr = chan->atr; 138 static struct i2c_atr_alias_pair *c2a; 139 int i; 140 141 /* Ensure we have enough room to save the original addresses */ 142 if (unlikely(chan->orig_addrs_size < num)) { 143 u16 *new_buf; 144 145 /* We don't care about old data, hence no realloc() */ 146 new_buf = kmalloc_array(num, sizeof(*new_buf), GFP_KERNEL); 147 if (!new_buf) 148 return -ENOMEM; 149 150 kfree(chan->orig_addrs); 151 chan->orig_addrs = new_buf; 152 chan->orig_addrs_size = num; 153 } 154 155 for (i = 0; i < num; i++) { 156 chan->orig_addrs[i] = msgs[i].addr; 157 158 c2a = i2c_atr_find_mapping_by_addr(&chan->alias_list, 159 msgs[i].addr); 160 if (!c2a) { 161 dev_err(atr->dev, "client 0x%02x not mapped!\n", 162 msgs[i].addr); 163 164 while (i--) 165 msgs[i].addr = chan->orig_addrs[i]; 166 167 return -ENXIO; 168 } 169 170 msgs[i].addr = c2a->alias; 171 } 172 173 return 0; 174} 175 176/* 177 * Restore all message address aliases with the original addresses. This 178 * function is internal for use in i2c_atr_master_xfer() and for this reason it 179 * needs no null and size checks on orig_addr. 180 * 181 * @see i2c_atr_map_msgs() 182 */ 183static void i2c_atr_unmap_msgs(struct i2c_atr_chan *chan, struct i2c_msg *msgs, 184 int num) 185{ 186 int i; 187 188 for (i = 0; i < num; i++) 189 msgs[i].addr = chan->orig_addrs[i]; 190} 191 192static int i2c_atr_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, 193 int num) 194{ 195 struct i2c_atr_chan *chan = adap->algo_data; 196 struct i2c_atr *atr = chan->atr; 197 struct i2c_adapter *parent = atr->parent; 198 int ret; 199 200 /* Translate addresses */ 201 mutex_lock(&chan->orig_addrs_lock); 202 203 ret = i2c_atr_map_msgs(chan, msgs, num); 204 if (ret < 0) 205 goto err_unlock; 206 207 /* Perform the transfer */ 208 ret = i2c_transfer(parent, msgs, num); 209 210 /* Restore addresses */ 211 i2c_atr_unmap_msgs(chan, msgs, num); 212 213err_unlock: 214 mutex_unlock(&chan->orig_addrs_lock); 215 216 return ret; 217} 218 219static int i2c_atr_smbus_xfer(struct i2c_adapter *adap, u16 addr, 220 unsigned short flags, char read_write, u8 command, 221 int size, union i2c_smbus_data *data) 222{ 223 struct i2c_atr_chan *chan = adap->algo_data; 224 struct i2c_atr *atr = chan->atr; 225 struct i2c_adapter *parent = atr->parent; 226 struct i2c_atr_alias_pair *c2a; 227 228 c2a = i2c_atr_find_mapping_by_addr(&chan->alias_list, addr); 229 if (!c2a) { 230 dev_err(atr->dev, "client 0x%02x not mapped!\n", addr); 231 return -ENXIO; 232 } 233 234 return i2c_smbus_xfer(parent, c2a->alias, flags, read_write, command, 235 size, data); 236} 237 238static u32 i2c_atr_functionality(struct i2c_adapter *adap) 239{ 240 struct i2c_atr_chan *chan = adap->algo_data; 241 struct i2c_adapter *parent = chan->atr->parent; 242 243 return parent->algo->functionality(parent); 244} 245 246static void i2c_atr_lock_bus(struct i2c_adapter *adapter, unsigned int flags) 247{ 248 struct i2c_atr_chan *chan = adapter->algo_data; 249 struct i2c_atr *atr = chan->atr; 250 251 mutex_lock(&atr->lock); 252} 253 254static int i2c_atr_trylock_bus(struct i2c_adapter *adapter, unsigned int flags) 255{ 256 struct i2c_atr_chan *chan = adapter->algo_data; 257 struct i2c_atr *atr = chan->atr; 258 259 return mutex_trylock(&atr->lock); 260} 261 262static void i2c_atr_unlock_bus(struct i2c_adapter *adapter, unsigned int flags) 263{ 264 struct i2c_atr_chan *chan = adapter->algo_data; 265 struct i2c_atr *atr = chan->atr; 266 267 mutex_unlock(&atr->lock); 268} 269 270static const struct i2c_lock_operations i2c_atr_lock_ops = { 271 .lock_bus = i2c_atr_lock_bus, 272 .trylock_bus = i2c_atr_trylock_bus, 273 .unlock_bus = i2c_atr_unlock_bus, 274}; 275 276static int i2c_atr_reserve_alias(struct i2c_atr *atr) 277{ 278 unsigned long idx; 279 280 spin_lock(&atr->alias_mask_lock); 281 282 idx = find_first_zero_bit(atr->alias_use_mask, atr->num_aliases); 283 if (idx >= atr->num_aliases) { 284 spin_unlock(&atr->alias_mask_lock); 285 dev_err(atr->dev, "failed to find a free alias\n"); 286 return -EBUSY; 287 } 288 289 set_bit(idx, atr->alias_use_mask); 290 291 spin_unlock(&atr->alias_mask_lock); 292 293 return atr->aliases[idx]; 294} 295 296static void i2c_atr_release_alias(struct i2c_atr *atr, u16 alias) 297{ 298 unsigned int idx; 299 300 spin_lock(&atr->alias_mask_lock); 301 302 for (idx = 0; idx < atr->num_aliases; ++idx) { 303 if (atr->aliases[idx] == alias) { 304 clear_bit(idx, atr->alias_use_mask); 305 spin_unlock(&atr->alias_mask_lock); 306 return; 307 } 308 } 309 310 spin_unlock(&atr->alias_mask_lock); 311 312 /* This should never happen */ 313 dev_warn(atr->dev, "Unable to find mapped alias\n"); 314} 315 316static int i2c_atr_attach_client(struct i2c_adapter *adapter, 317 const struct i2c_client *client) 318{ 319 struct i2c_atr_chan *chan = adapter->algo_data; 320 struct i2c_atr *atr = chan->atr; 321 struct i2c_atr_alias_pair *c2a; 322 u16 alias; 323 int ret; 324 325 ret = i2c_atr_reserve_alias(atr); 326 if (ret < 0) 327 return ret; 328 329 alias = ret; 330 331 c2a = kzalloc(sizeof(*c2a), GFP_KERNEL); 332 if (!c2a) { 333 ret = -ENOMEM; 334 goto err_release_alias; 335 } 336 337 ret = atr->ops->attach_client(atr, chan->chan_id, client, alias); 338 if (ret) 339 goto err_free; 340 341 dev_dbg(atr->dev, "chan%u: client 0x%02x mapped at alias 0x%02x (%s)\n", 342 chan->chan_id, client->addr, alias, client->name); 343 344 c2a->client = client; 345 c2a->alias = alias; 346 list_add(&c2a->node, &chan->alias_list); 347 348 return 0; 349 350err_free: 351 kfree(c2a); 352err_release_alias: 353 i2c_atr_release_alias(atr, alias); 354 355 return ret; 356} 357 358static void i2c_atr_detach_client(struct i2c_adapter *adapter, 359 const struct i2c_client *client) 360{ 361 struct i2c_atr_chan *chan = adapter->algo_data; 362 struct i2c_atr *atr = chan->atr; 363 struct i2c_atr_alias_pair *c2a; 364 365 atr->ops->detach_client(atr, chan->chan_id, client); 366 367 c2a = i2c_atr_find_mapping_by_client(&chan->alias_list, client); 368 if (!c2a) { 369 /* This should never happen */ 370 dev_warn(atr->dev, "Unable to find address mapping\n"); 371 return; 372 } 373 374 i2c_atr_release_alias(atr, c2a->alias); 375 376 dev_dbg(atr->dev, 377 "chan%u: client 0x%02x unmapped from alias 0x%02x (%s)\n", 378 chan->chan_id, client->addr, c2a->alias, client->name); 379 380 list_del(&c2a->node); 381 kfree(c2a); 382} 383 384static int i2c_atr_bus_notifier_call(struct notifier_block *nb, 385 unsigned long event, void *device) 386{ 387 struct i2c_atr *atr = container_of(nb, struct i2c_atr, i2c_nb); 388 struct device *dev = device; 389 struct i2c_client *client; 390 u32 chan_id; 391 int ret; 392 393 client = i2c_verify_client(dev); 394 if (!client) 395 return NOTIFY_DONE; 396 397 /* Is the client in one of our adapters? */ 398 for (chan_id = 0; chan_id < atr->max_adapters; ++chan_id) { 399 if (client->adapter == atr->adapter[chan_id]) 400 break; 401 } 402 403 if (chan_id == atr->max_adapters) 404 return NOTIFY_DONE; 405 406 switch (event) { 407 case BUS_NOTIFY_ADD_DEVICE: 408 ret = i2c_atr_attach_client(client->adapter, client); 409 if (ret) 410 dev_err(atr->dev, 411 "Failed to attach remote client '%s': %d\n", 412 dev_name(dev), ret); 413 break; 414 415 case BUS_NOTIFY_DEL_DEVICE: 416 i2c_atr_detach_client(client->adapter, client); 417 break; 418 419 default: 420 break; 421 } 422 423 return NOTIFY_DONE; 424} 425 426static int i2c_atr_parse_alias_pool(struct i2c_atr *atr) 427{ 428 struct device *dev = atr->dev; 429 unsigned long *alias_use_mask; 430 size_t num_aliases; 431 unsigned int i; 432 u32 *aliases32; 433 u16 *aliases16; 434 int ret; 435 436 ret = fwnode_property_count_u32(dev_fwnode(dev), "i2c-alias-pool"); 437 if (ret < 0) { 438 dev_err(dev, "Failed to count 'i2c-alias-pool' property: %d\n", 439 ret); 440 return ret; 441 } 442 443 num_aliases = ret; 444 445 if (!num_aliases) 446 return 0; 447 448 aliases32 = kcalloc(num_aliases, sizeof(*aliases32), GFP_KERNEL); 449 if (!aliases32) 450 return -ENOMEM; 451 452 ret = fwnode_property_read_u32_array(dev_fwnode(dev), "i2c-alias-pool", 453 aliases32, num_aliases); 454 if (ret < 0) { 455 dev_err(dev, "Failed to read 'i2c-alias-pool' property: %d\n", 456 ret); 457 goto err_free_aliases32; 458 } 459 460 aliases16 = kcalloc(num_aliases, sizeof(*aliases16), GFP_KERNEL); 461 if (!aliases16) { 462 ret = -ENOMEM; 463 goto err_free_aliases32; 464 } 465 466 for (i = 0; i < num_aliases; i++) { 467 if (!(aliases32[i] & 0xffff0000)) { 468 aliases16[i] = aliases32[i]; 469 continue; 470 } 471 472 dev_err(dev, "Failed to parse 'i2c-alias-pool' property: I2C flags are not supported\n"); 473 ret = -EINVAL; 474 goto err_free_aliases16; 475 } 476 477 alias_use_mask = bitmap_zalloc(num_aliases, GFP_KERNEL); 478 if (!alias_use_mask) { 479 ret = -ENOMEM; 480 goto err_free_aliases16; 481 } 482 483 kfree(aliases32); 484 485 atr->num_aliases = num_aliases; 486 atr->aliases = aliases16; 487 atr->alias_use_mask = alias_use_mask; 488 489 dev_dbg(dev, "i2c-alias-pool has %zu aliases", atr->num_aliases); 490 491 return 0; 492 493err_free_aliases16: 494 kfree(aliases16); 495err_free_aliases32: 496 kfree(aliases32); 497 return ret; 498} 499 500struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev, 501 const struct i2c_atr_ops *ops, int max_adapters) 502{ 503 struct i2c_atr *atr; 504 int ret; 505 506 if (max_adapters > ATR_MAX_ADAPTERS) 507 return ERR_PTR(-EINVAL); 508 509 if (!ops || !ops->attach_client || !ops->detach_client) 510 return ERR_PTR(-EINVAL); 511 512 atr = kzalloc(struct_size(atr, adapter, max_adapters), GFP_KERNEL); 513 if (!atr) 514 return ERR_PTR(-ENOMEM); 515 516 mutex_init(&atr->lock); 517 spin_lock_init(&atr->alias_mask_lock); 518 519 atr->parent = parent; 520 atr->dev = dev; 521 atr->ops = ops; 522 atr->max_adapters = max_adapters; 523 524 if (parent->algo->master_xfer) 525 atr->algo.master_xfer = i2c_atr_master_xfer; 526 if (parent->algo->smbus_xfer) 527 atr->algo.smbus_xfer = i2c_atr_smbus_xfer; 528 atr->algo.functionality = i2c_atr_functionality; 529 530 ret = i2c_atr_parse_alias_pool(atr); 531 if (ret) 532 goto err_destroy_mutex; 533 534 atr->i2c_nb.notifier_call = i2c_atr_bus_notifier_call; 535 ret = bus_register_notifier(&i2c_bus_type, &atr->i2c_nb); 536 if (ret) 537 goto err_free_aliases; 538 539 return atr; 540 541err_free_aliases: 542 bitmap_free(atr->alias_use_mask); 543 kfree(atr->aliases); 544err_destroy_mutex: 545 mutex_destroy(&atr->lock); 546 kfree(atr); 547 548 return ERR_PTR(ret); 549} 550EXPORT_SYMBOL_NS_GPL(i2c_atr_new, I2C_ATR); 551 552void i2c_atr_delete(struct i2c_atr *atr) 553{ 554 unsigned int i; 555 556 for (i = 0; i < atr->max_adapters; ++i) 557 WARN_ON(atr->adapter[i]); 558 559 bus_unregister_notifier(&i2c_bus_type, &atr->i2c_nb); 560 bitmap_free(atr->alias_use_mask); 561 kfree(atr->aliases); 562 mutex_destroy(&atr->lock); 563 kfree(atr); 564} 565EXPORT_SYMBOL_NS_GPL(i2c_atr_delete, I2C_ATR); 566 567int i2c_atr_add_adapter(struct i2c_atr *atr, u32 chan_id, 568 struct device *adapter_parent, 569 struct fwnode_handle *bus_handle) 570{ 571 struct i2c_adapter *parent = atr->parent; 572 struct device *dev = atr->dev; 573 struct i2c_atr_chan *chan; 574 char symlink_name[ATR_MAX_SYMLINK_LEN]; 575 int ret; 576 577 if (chan_id >= atr->max_adapters) { 578 dev_err(dev, "No room for more i2c-atr adapters\n"); 579 return -EINVAL; 580 } 581 582 if (atr->adapter[chan_id]) { 583 dev_err(dev, "Adapter %d already present\n", chan_id); 584 return -EEXIST; 585 } 586 587 chan = kzalloc(sizeof(*chan), GFP_KERNEL); 588 if (!chan) 589 return -ENOMEM; 590 591 if (!adapter_parent) 592 adapter_parent = dev; 593 594 chan->atr = atr; 595 chan->chan_id = chan_id; 596 INIT_LIST_HEAD(&chan->alias_list); 597 mutex_init(&chan->orig_addrs_lock); 598 599 snprintf(chan->adap.name, sizeof(chan->adap.name), "i2c-%d-atr-%d", 600 i2c_adapter_id(parent), chan_id); 601 chan->adap.owner = THIS_MODULE; 602 chan->adap.algo = &atr->algo; 603 chan->adap.algo_data = chan; 604 chan->adap.dev.parent = adapter_parent; 605 chan->adap.retries = parent->retries; 606 chan->adap.timeout = parent->timeout; 607 chan->adap.quirks = parent->quirks; 608 chan->adap.lock_ops = &i2c_atr_lock_ops; 609 610 if (bus_handle) { 611 device_set_node(&chan->adap.dev, fwnode_handle_get(bus_handle)); 612 } else { 613 struct fwnode_handle *atr_node; 614 struct fwnode_handle *child; 615 u32 reg; 616 617 atr_node = device_get_named_child_node(dev, "i2c-atr"); 618 619 fwnode_for_each_child_node(atr_node, child) { 620 ret = fwnode_property_read_u32(child, "reg", ®); 621 if (ret) 622 continue; 623 if (chan_id == reg) 624 break; 625 } 626 627 device_set_node(&chan->adap.dev, child); 628 fwnode_handle_put(atr_node); 629 } 630 631 atr->adapter[chan_id] = &chan->adap; 632 633 ret = i2c_add_adapter(&chan->adap); 634 if (ret) { 635 dev_err(dev, "failed to add atr-adapter %u (error=%d)\n", 636 chan_id, ret); 637 goto err_fwnode_put; 638 } 639 640 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", 641 chan->chan_id); 642 643 ret = sysfs_create_link(&chan->adap.dev.kobj, &dev->kobj, "atr_device"); 644 if (ret) 645 dev_warn(dev, "can't create symlink to atr device\n"); 646 ret = sysfs_create_link(&dev->kobj, &chan->adap.dev.kobj, symlink_name); 647 if (ret) 648 dev_warn(dev, "can't create symlink for channel %u\n", chan_id); 649 650 dev_dbg(dev, "Added ATR child bus %d\n", i2c_adapter_id(&chan->adap)); 651 652 return 0; 653 654err_fwnode_put: 655 fwnode_handle_put(dev_fwnode(&chan->adap.dev)); 656 mutex_destroy(&chan->orig_addrs_lock); 657 kfree(chan); 658 return ret; 659} 660EXPORT_SYMBOL_NS_GPL(i2c_atr_add_adapter, I2C_ATR); 661 662void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id) 663{ 664 char symlink_name[ATR_MAX_SYMLINK_LEN]; 665 struct i2c_adapter *adap; 666 struct i2c_atr_chan *chan; 667 struct fwnode_handle *fwnode; 668 struct device *dev = atr->dev; 669 670 adap = atr->adapter[chan_id]; 671 if (!adap) 672 return; 673 674 chan = adap->algo_data; 675 fwnode = dev_fwnode(&adap->dev); 676 677 dev_dbg(dev, "Removing ATR child bus %d\n", i2c_adapter_id(adap)); 678 679 snprintf(symlink_name, sizeof(symlink_name), "channel-%u", 680 chan->chan_id); 681 sysfs_remove_link(&dev->kobj, symlink_name); 682 sysfs_remove_link(&chan->adap.dev.kobj, "atr_device"); 683 684 i2c_del_adapter(adap); 685 686 atr->adapter[chan_id] = NULL; 687 688 fwnode_handle_put(fwnode); 689 mutex_destroy(&chan->orig_addrs_lock); 690 kfree(chan->orig_addrs); 691 kfree(chan); 692} 693EXPORT_SYMBOL_NS_GPL(i2c_atr_del_adapter, I2C_ATR); 694 695void i2c_atr_set_driver_data(struct i2c_atr *atr, void *data) 696{ 697 atr->priv = data; 698} 699EXPORT_SYMBOL_NS_GPL(i2c_atr_set_driver_data, I2C_ATR); 700 701void *i2c_atr_get_driver_data(struct i2c_atr *atr) 702{ 703 return atr->priv; 704} 705EXPORT_SYMBOL_NS_GPL(i2c_atr_get_driver_data, I2C_ATR); 706 707MODULE_AUTHOR("Luca Ceresoli <luca.ceresoli@bootlin.com>"); 708MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>"); 709MODULE_DESCRIPTION("I2C Address Translator"); 710MODULE_LICENSE("GPL"); 711