1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * Linux I2C core 4 * 5 * Copyright (C) 1995-99 Simon G. Vogl 6 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> 7 * Mux support by Rodolfo Giometti <giometti@enneenne.com> and 8 * Michael Lawnick <michael.lawnick.ext@nsn.com> 9 * 10 * Copyright (C) 2013-2017 Wolfram Sang <wsa@kernel.org> 11 */ 12 13#define pr_fmt(fmt) "i2c-core: " fmt 14 15#include <dt-bindings/i2c/i2c.h> 16#include <linux/acpi.h> 17#include <linux/clk/clk-conf.h> 18#include <linux/completion.h> 19#include <linux/delay.h> 20#include <linux/err.h> 21#include <linux/errno.h> 22#include <linux/gpio/consumer.h> 23#include <linux/i2c.h> 24#include <linux/i2c-smbus.h> 25#include <linux/idr.h> 26#include <linux/init.h> 27#include <linux/interrupt.h> 28#include <linux/irqflags.h> 29#include <linux/jump_label.h> 30#include <linux/kernel.h> 31#include <linux/module.h> 32#include <linux/mutex.h> 33#include <linux/of_device.h> 34#include <linux/of.h> 35#include <linux/of_irq.h> 36#include <linux/pinctrl/consumer.h> 37#include <linux/pinctrl/devinfo.h> 38#include <linux/pm_domain.h> 39#include <linux/pm_runtime.h> 40#include <linux/pm_wakeirq.h> 41#include <linux/property.h> 42#include <linux/rwsem.h> 43#include <linux/slab.h> 44 45#include "i2c-core.h" 46 47#define CREATE_TRACE_POINTS 48#include <trace/events/i2c.h> 49 50#define I2C_ADDR_OFFSET_TEN_BIT 0xa000 51#define I2C_ADDR_OFFSET_SLAVE 0x1000 52 53#define I2C_ADDR_7BITS_MAX 0x77 54#define I2C_ADDR_7BITS_COUNT (I2C_ADDR_7BITS_MAX + 1) 55 56#define I2C_ADDR_DEVICE_ID 0x7c 57 58/* 59 * core_lock protects i2c_adapter_idr, and guarantees that device detection, 60 * deletion of detected devices are serialized 61 */ 62static DEFINE_MUTEX(core_lock); 63static DEFINE_IDR(i2c_adapter_idr); 64 65static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver); 66 67static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key); 68static bool is_registered; 69 70int i2c_transfer_trace_reg(void) 71{ 72 static_branch_inc(&i2c_trace_msg_key); 73 return 0; 74} 75 76void i2c_transfer_trace_unreg(void) 77{ 78 static_branch_dec(&i2c_trace_msg_key); 79} 80 81const char *i2c_freq_mode_string(u32 bus_freq_hz) 82{ 83 switch (bus_freq_hz) { 84 case I2C_MAX_STANDARD_MODE_FREQ: 85 return "Standard Mode (100 kHz)"; 86 case I2C_MAX_FAST_MODE_FREQ: 87 return "Fast Mode (400 kHz)"; 88 case I2C_MAX_FAST_MODE_PLUS_FREQ: 89 return "Fast Mode Plus (1.0 MHz)"; 90 case I2C_MAX_TURBO_MODE_FREQ: 91 return "Turbo Mode (1.4 MHz)"; 92 case I2C_MAX_HIGH_SPEED_MODE_FREQ: 93 return "High Speed Mode (3.4 MHz)"; 94 case I2C_MAX_ULTRA_FAST_MODE_FREQ: 95 return "Ultra Fast Mode (5.0 MHz)"; 96 default: 97 return "Unknown Mode"; 98 } 99} 100EXPORT_SYMBOL_GPL(i2c_freq_mode_string); 101 102const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id, 103 const struct i2c_client *client) 104{ 105 if (!(id && client)) 106 return NULL; 107 108 while (id->name[0]) { 109 if (strcmp(client->name, id->name) == 0) 110 return id; 111 id++; 112 } 113 return NULL; 114} 115EXPORT_SYMBOL_GPL(i2c_match_id); 116 117const void *i2c_get_match_data(const struct i2c_client *client) 118{ 119 struct i2c_driver *driver = to_i2c_driver(client->dev.driver); 120 const struct i2c_device_id *match; 121 const void *data; 122 123 data = device_get_match_data(&client->dev); 124 if (!data) { 125 match = i2c_match_id(driver->id_table, client); 126 if (!match) 127 return NULL; 128 129 data = (const void *)match->driver_data; 130 } 131 132 return data; 133} 134EXPORT_SYMBOL(i2c_get_match_data); 135 136static int i2c_device_match(struct device *dev, struct device_driver *drv) 137{ 138 struct i2c_client *client = i2c_verify_client(dev); 139 struct i2c_driver *driver; 140 141 142 /* Attempt an OF style match */ 143 if (i2c_of_match_device(drv->of_match_table, client)) 144 return 1; 145 146 /* Then ACPI style match */ 147 if (acpi_driver_match_device(dev, drv)) 148 return 1; 149 150 driver = to_i2c_driver(drv); 151 152 /* Finally an I2C match */ 153 if (i2c_match_id(driver->id_table, client)) 154 return 1; 155 156 return 0; 157} 158 159static int i2c_device_uevent(const struct device *dev, struct kobj_uevent_env *env) 160{ 161 const struct i2c_client *client = to_i2c_client(dev); 162 int rc; 163 164 rc = of_device_uevent_modalias(dev, env); 165 if (rc != -ENODEV) 166 return rc; 167 168 rc = acpi_device_uevent_modalias(dev, env); 169 if (rc != -ENODEV) 170 return rc; 171 172 return add_uevent_var(env, "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name); 173} 174 175/* i2c bus recovery routines */ 176static int get_scl_gpio_value(struct i2c_adapter *adap) 177{ 178 return gpiod_get_value_cansleep(adap->bus_recovery_info->scl_gpiod); 179} 180 181static void set_scl_gpio_value(struct i2c_adapter *adap, int val) 182{ 183 gpiod_set_value_cansleep(adap->bus_recovery_info->scl_gpiod, val); 184} 185 186static int get_sda_gpio_value(struct i2c_adapter *adap) 187{ 188 return gpiod_get_value_cansleep(adap->bus_recovery_info->sda_gpiod); 189} 190 191static void set_sda_gpio_value(struct i2c_adapter *adap, int val) 192{ 193 gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val); 194} 195 196static int i2c_generic_bus_free(struct i2c_adapter *adap) 197{ 198 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 199 int ret = -EOPNOTSUPP; 200 201 if (bri->get_bus_free) 202 ret = bri->get_bus_free(adap); 203 else if (bri->get_sda) 204 ret = bri->get_sda(adap); 205 206 if (ret < 0) 207 return ret; 208 209 return ret ? 0 : -EBUSY; 210} 211 212/* 213 * We are generating clock pulses. ndelay() determines durating of clk pulses. 214 * We will generate clock with rate 100 KHz and so duration of both clock levels 215 * is: delay in ns = (10^6 / 100) / 2 216 */ 217#define RECOVERY_NDELAY 5000 218#define RECOVERY_CLK_CNT 9 219 220int i2c_generic_scl_recovery(struct i2c_adapter *adap) 221{ 222 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 223 int i = 0, scl = 1, ret = 0; 224 225 if (bri->prepare_recovery) 226 bri->prepare_recovery(adap); 227 if (bri->pinctrl) 228 pinctrl_select_state(bri->pinctrl, bri->pins_gpio); 229 230 /* 231 * If we can set SDA, we will always create a STOP to ensure additional 232 * pulses will do no harm. This is achieved by letting SDA follow SCL 233 * half a cycle later. Check the 'incomplete_write_byte' fault injector 234 * for details. Note that we must honour tsu:sto, 4us, but lets use 5us 235 * here for simplicity. 236 */ 237 bri->set_scl(adap, scl); 238 ndelay(RECOVERY_NDELAY); 239 if (bri->set_sda) 240 bri->set_sda(adap, scl); 241 ndelay(RECOVERY_NDELAY / 2); 242 243 /* 244 * By this time SCL is high, as we need to give 9 falling-rising edges 245 */ 246 while (i++ < RECOVERY_CLK_CNT * 2) { 247 if (scl) { 248 /* SCL shouldn't be low here */ 249 if (!bri->get_scl(adap)) { 250 dev_err(&adap->dev, 251 "SCL is stuck low, exit recovery\n"); 252 ret = -EBUSY; 253 break; 254 } 255 } 256 257 scl = !scl; 258 bri->set_scl(adap, scl); 259 /* Creating STOP again, see above */ 260 if (scl) { 261 /* Honour minimum tsu:sto */ 262 ndelay(RECOVERY_NDELAY); 263 } else { 264 /* Honour minimum tf and thd:dat */ 265 ndelay(RECOVERY_NDELAY / 2); 266 } 267 if (bri->set_sda) 268 bri->set_sda(adap, scl); 269 ndelay(RECOVERY_NDELAY / 2); 270 271 if (scl) { 272 ret = i2c_generic_bus_free(adap); 273 if (ret == 0) 274 break; 275 } 276 } 277 278 /* If we can't check bus status, assume recovery worked */ 279 if (ret == -EOPNOTSUPP) 280 ret = 0; 281 282 if (bri->unprepare_recovery) 283 bri->unprepare_recovery(adap); 284 if (bri->pinctrl) 285 pinctrl_select_state(bri->pinctrl, bri->pins_default); 286 287 return ret; 288} 289EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery); 290 291int i2c_recover_bus(struct i2c_adapter *adap) 292{ 293 if (!adap->bus_recovery_info) 294 return -EBUSY; 295 296 dev_dbg(&adap->dev, "Trying i2c bus recovery\n"); 297 return adap->bus_recovery_info->recover_bus(adap); 298} 299EXPORT_SYMBOL_GPL(i2c_recover_bus); 300 301static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap) 302{ 303 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 304 struct device *dev = &adap->dev; 305 struct pinctrl *p = bri->pinctrl ?: dev_pinctrl(dev->parent); 306 307 bri->pinctrl = p; 308 309 /* 310 * we can't change states without pinctrl, so remove the states if 311 * populated 312 */ 313 if (!p) { 314 bri->pins_default = NULL; 315 bri->pins_gpio = NULL; 316 return; 317 } 318 319 if (!bri->pins_default) { 320 bri->pins_default = pinctrl_lookup_state(p, 321 PINCTRL_STATE_DEFAULT); 322 if (IS_ERR(bri->pins_default)) { 323 dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found for GPIO recovery\n"); 324 bri->pins_default = NULL; 325 } 326 } 327 if (!bri->pins_gpio) { 328 bri->pins_gpio = pinctrl_lookup_state(p, "gpio"); 329 if (IS_ERR(bri->pins_gpio)) 330 bri->pins_gpio = pinctrl_lookup_state(p, "recovery"); 331 332 if (IS_ERR(bri->pins_gpio)) { 333 dev_dbg(dev, "no gpio or recovery state found for GPIO recovery\n"); 334 bri->pins_gpio = NULL; 335 } 336 } 337 338 /* for pinctrl state changes, we need all the information */ 339 if (bri->pins_default && bri->pins_gpio) { 340 dev_info(dev, "using pinctrl states for GPIO recovery"); 341 } else { 342 bri->pinctrl = NULL; 343 bri->pins_default = NULL; 344 bri->pins_gpio = NULL; 345 } 346} 347 348static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap) 349{ 350 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 351 struct device *dev = &adap->dev; 352 struct gpio_desc *gpiod; 353 int ret = 0; 354 355 /* 356 * don't touch the recovery information if the driver is not using 357 * generic SCL recovery 358 */ 359 if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery) 360 return 0; 361 362 /* 363 * pins might be taken as GPIO, so we should inform pinctrl about 364 * this and move the state to GPIO 365 */ 366 if (bri->pinctrl) 367 pinctrl_select_state(bri->pinctrl, bri->pins_gpio); 368 369 /* 370 * if there is incomplete or no recovery information, see if generic 371 * GPIO recovery is available 372 */ 373 if (!bri->scl_gpiod) { 374 gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN); 375 if (PTR_ERR(gpiod) == -EPROBE_DEFER) { 376 ret = -EPROBE_DEFER; 377 goto cleanup_pinctrl_state; 378 } 379 if (!IS_ERR(gpiod)) { 380 bri->scl_gpiod = gpiod; 381 bri->recover_bus = i2c_generic_scl_recovery; 382 dev_info(dev, "using generic GPIOs for recovery\n"); 383 } 384 } 385 386 /* SDA GPIOD line is optional, so we care about DEFER only */ 387 if (!bri->sda_gpiod) { 388 /* 389 * We have SCL. Pull SCL low and wait a bit so that SDA glitches 390 * have no effect. 391 */ 392 gpiod_direction_output(bri->scl_gpiod, 0); 393 udelay(10); 394 gpiod = devm_gpiod_get(dev, "sda", GPIOD_IN); 395 396 /* Wait a bit in case of a SDA glitch, and then release SCL. */ 397 udelay(10); 398 gpiod_direction_output(bri->scl_gpiod, 1); 399 400 if (PTR_ERR(gpiod) == -EPROBE_DEFER) { 401 ret = -EPROBE_DEFER; 402 goto cleanup_pinctrl_state; 403 } 404 if (!IS_ERR(gpiod)) 405 bri->sda_gpiod = gpiod; 406 } 407 408cleanup_pinctrl_state: 409 /* change the state of the pins back to their default state */ 410 if (bri->pinctrl) 411 pinctrl_select_state(bri->pinctrl, bri->pins_default); 412 413 return ret; 414} 415 416static int i2c_gpio_init_recovery(struct i2c_adapter *adap) 417{ 418 i2c_gpio_init_pinctrl_recovery(adap); 419 return i2c_gpio_init_generic_recovery(adap); 420} 421 422static int i2c_init_recovery(struct i2c_adapter *adap) 423{ 424 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 425 bool is_error_level = true; 426 char *err_str; 427 428 if (!bri) 429 return 0; 430 431 if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER) 432 return -EPROBE_DEFER; 433 434 if (!bri->recover_bus) { 435 err_str = "no suitable method provided"; 436 is_error_level = false; 437 goto err; 438 } 439 440 if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) { 441 bri->get_scl = get_scl_gpio_value; 442 bri->set_scl = set_scl_gpio_value; 443 if (bri->sda_gpiod) { 444 bri->get_sda = get_sda_gpio_value; 445 /* FIXME: add proper flag instead of '0' once available */ 446 if (gpiod_get_direction(bri->sda_gpiod) == 0) 447 bri->set_sda = set_sda_gpio_value; 448 } 449 } else if (bri->recover_bus == i2c_generic_scl_recovery) { 450 /* Generic SCL recovery */ 451 if (!bri->set_scl || !bri->get_scl) { 452 err_str = "no {get|set}_scl() found"; 453 goto err; 454 } 455 if (!bri->set_sda && !bri->get_sda) { 456 err_str = "either get_sda() or set_sda() needed"; 457 goto err; 458 } 459 } 460 461 return 0; 462 err: 463 if (is_error_level) 464 dev_err(&adap->dev, "Not using recovery: %s\n", err_str); 465 else 466 dev_dbg(&adap->dev, "Not using recovery: %s\n", err_str); 467 adap->bus_recovery_info = NULL; 468 469 return -EINVAL; 470} 471 472static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client) 473{ 474 struct i2c_adapter *adap = client->adapter; 475 unsigned int irq; 476 477 if (!adap->host_notify_domain) 478 return -ENXIO; 479 480 if (client->flags & I2C_CLIENT_TEN) 481 return -EINVAL; 482 483 irq = irq_create_mapping(adap->host_notify_domain, client->addr); 484 485 return irq > 0 ? irq : -ENXIO; 486} 487 488static int i2c_device_probe(struct device *dev) 489{ 490 struct i2c_client *client = i2c_verify_client(dev); 491 struct i2c_driver *driver; 492 bool do_power_on; 493 int status; 494 495 if (!client) 496 return 0; 497 498 client->irq = client->init_irq; 499 500 if (!client->irq) { 501 int irq = -ENOENT; 502 503 if (client->flags & I2C_CLIENT_HOST_NOTIFY) { 504 dev_dbg(dev, "Using Host Notify IRQ\n"); 505 /* Keep adapter active when Host Notify is required */ 506 pm_runtime_get_sync(&client->adapter->dev); 507 irq = i2c_smbus_host_notify_to_irq(client); 508 } else if (dev->of_node) { 509 irq = of_irq_get_byname(dev->of_node, "irq"); 510 if (irq == -EINVAL || irq == -ENODATA) 511 irq = of_irq_get(dev->of_node, 0); 512 } else if (ACPI_COMPANION(dev)) { 513 bool wake_capable; 514 515 irq = i2c_acpi_get_irq(client, &wake_capable); 516 if (irq > 0 && wake_capable) 517 client->flags |= I2C_CLIENT_WAKE; 518 } 519 if (irq == -EPROBE_DEFER) { 520 status = irq; 521 goto put_sync_adapter; 522 } 523 524 if (irq < 0) 525 irq = 0; 526 527 client->irq = irq; 528 } 529 530 driver = to_i2c_driver(dev->driver); 531 532 /* 533 * An I2C ID table is not mandatory, if and only if, a suitable OF 534 * or ACPI ID table is supplied for the probing device. 535 */ 536 if (!driver->id_table && 537 !acpi_driver_match_device(dev, dev->driver) && 538 !i2c_of_match_device(dev->driver->of_match_table, client)) { 539 status = -ENODEV; 540 goto put_sync_adapter; 541 } 542 543 if (client->flags & I2C_CLIENT_WAKE) { 544 int wakeirq; 545 546 wakeirq = of_irq_get_byname(dev->of_node, "wakeup"); 547 if (wakeirq == -EPROBE_DEFER) { 548 status = wakeirq; 549 goto put_sync_adapter; 550 } 551 552 device_init_wakeup(&client->dev, true); 553 554 if (wakeirq > 0 && wakeirq != client->irq) 555 status = dev_pm_set_dedicated_wake_irq(dev, wakeirq); 556 else if (client->irq > 0) 557 status = dev_pm_set_wake_irq(dev, client->irq); 558 else 559 status = 0; 560 561 if (status) 562 dev_warn(&client->dev, "failed to set up wakeup irq\n"); 563 } 564 565 dev_dbg(dev, "probe\n"); 566 567 status = of_clk_set_defaults(dev->of_node, false); 568 if (status < 0) 569 goto err_clear_wakeup_irq; 570 571 do_power_on = !i2c_acpi_waive_d0_probe(dev); 572 status = dev_pm_domain_attach(&client->dev, do_power_on); 573 if (status) 574 goto err_clear_wakeup_irq; 575 576 client->devres_group_id = devres_open_group(&client->dev, NULL, 577 GFP_KERNEL); 578 if (!client->devres_group_id) { 579 status = -ENOMEM; 580 goto err_detach_pm_domain; 581 } 582 583 if (driver->probe) 584 status = driver->probe(client); 585 else 586 status = -EINVAL; 587 588 /* 589 * Note that we are not closing the devres group opened above so 590 * even resources that were attached to the device after probe is 591 * run are released when i2c_device_remove() is executed. This is 592 * needed as some drivers would allocate additional resources, 593 * for example when updating firmware. 594 */ 595 596 if (status) 597 goto err_release_driver_resources; 598 599 return 0; 600 601err_release_driver_resources: 602 devres_release_group(&client->dev, client->devres_group_id); 603err_detach_pm_domain: 604 dev_pm_domain_detach(&client->dev, do_power_on); 605err_clear_wakeup_irq: 606 dev_pm_clear_wake_irq(&client->dev); 607 device_init_wakeup(&client->dev, false); 608put_sync_adapter: 609 if (client->flags & I2C_CLIENT_HOST_NOTIFY) 610 pm_runtime_put_sync(&client->adapter->dev); 611 612 return status; 613} 614 615static void i2c_device_remove(struct device *dev) 616{ 617 struct i2c_client *client = to_i2c_client(dev); 618 struct i2c_driver *driver; 619 620 driver = to_i2c_driver(dev->driver); 621 if (driver->remove) { 622 dev_dbg(dev, "remove\n"); 623 624 driver->remove(client); 625 } 626 627 devres_release_group(&client->dev, client->devres_group_id); 628 629 dev_pm_domain_detach(&client->dev, true); 630 631 dev_pm_clear_wake_irq(&client->dev); 632 device_init_wakeup(&client->dev, false); 633 634 client->irq = 0; 635 if (client->flags & I2C_CLIENT_HOST_NOTIFY) 636 pm_runtime_put(&client->adapter->dev); 637} 638 639static void i2c_device_shutdown(struct device *dev) 640{ 641 struct i2c_client *client = i2c_verify_client(dev); 642 struct i2c_driver *driver; 643 644 if (!client || !dev->driver) 645 return; 646 driver = to_i2c_driver(dev->driver); 647 if (driver->shutdown) 648 driver->shutdown(client); 649 else if (client->irq > 0) 650 disable_irq(client->irq); 651} 652 653static void i2c_client_dev_release(struct device *dev) 654{ 655 kfree(to_i2c_client(dev)); 656} 657 658static ssize_t 659name_show(struct device *dev, struct device_attribute *attr, char *buf) 660{ 661 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ? 662 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name); 663} 664static DEVICE_ATTR_RO(name); 665 666static ssize_t 667modalias_show(struct device *dev, struct device_attribute *attr, char *buf) 668{ 669 struct i2c_client *client = to_i2c_client(dev); 670 int len; 671 672 len = of_device_modalias(dev, buf, PAGE_SIZE); 673 if (len != -ENODEV) 674 return len; 675 676 len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1); 677 if (len != -ENODEV) 678 return len; 679 680 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name); 681} 682static DEVICE_ATTR_RO(modalias); 683 684static struct attribute *i2c_dev_attrs[] = { 685 &dev_attr_name.attr, 686 /* modalias helps coldplug: modprobe $(cat .../modalias) */ 687 &dev_attr_modalias.attr, 688 NULL 689}; 690ATTRIBUTE_GROUPS(i2c_dev); 691 692struct bus_type i2c_bus_type = { 693 .name = "i2c", 694 .match = i2c_device_match, 695 .probe = i2c_device_probe, 696 .remove = i2c_device_remove, 697 .shutdown = i2c_device_shutdown, 698}; 699EXPORT_SYMBOL_GPL(i2c_bus_type); 700 701struct device_type i2c_client_type = { 702 .groups = i2c_dev_groups, 703 .uevent = i2c_device_uevent, 704 .release = i2c_client_dev_release, 705}; 706EXPORT_SYMBOL_GPL(i2c_client_type); 707 708 709/** 710 * i2c_verify_client - return parameter as i2c_client, or NULL 711 * @dev: device, probably from some driver model iterator 712 * 713 * When traversing the driver model tree, perhaps using driver model 714 * iterators like @device_for_each_child(), you can't assume very much 715 * about the nodes you find. Use this function to avoid oopses caused 716 * by wrongly treating some non-I2C device as an i2c_client. 717 */ 718struct i2c_client *i2c_verify_client(struct device *dev) 719{ 720 return (dev->type == &i2c_client_type) 721 ? to_i2c_client(dev) 722 : NULL; 723} 724EXPORT_SYMBOL(i2c_verify_client); 725 726 727/* Return a unique address which takes the flags of the client into account */ 728static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client) 729{ 730 unsigned short addr = client->addr; 731 732 /* For some client flags, add an arbitrary offset to avoid collisions */ 733 if (client->flags & I2C_CLIENT_TEN) 734 addr |= I2C_ADDR_OFFSET_TEN_BIT; 735 736 if (client->flags & I2C_CLIENT_SLAVE) 737 addr |= I2C_ADDR_OFFSET_SLAVE; 738 739 return addr; 740} 741 742/* This is a permissive address validity check, I2C address map constraints 743 * are purposely not enforced, except for the general call address. */ 744static int i2c_check_addr_validity(unsigned int addr, unsigned short flags) 745{ 746 if (flags & I2C_CLIENT_TEN) { 747 /* 10-bit address, all values are valid */ 748 if (addr > 0x3ff) 749 return -EINVAL; 750 } else { 751 /* 7-bit address, reject the general call address */ 752 if (addr == 0x00 || addr > 0x7f) 753 return -EINVAL; 754 } 755 return 0; 756} 757 758/* And this is a strict address validity check, used when probing. If a 759 * device uses a reserved address, then it shouldn't be probed. 7-bit 760 * addressing is assumed, 10-bit address devices are rare and should be 761 * explicitly enumerated. */ 762int i2c_check_7bit_addr_validity_strict(unsigned short addr) 763{ 764 /* 765 * Reserved addresses per I2C specification: 766 * 0x00 General call address / START byte 767 * 0x01 CBUS address 768 * 0x02 Reserved for different bus format 769 * 0x03 Reserved for future purposes 770 * 0x04-0x07 Hs-mode master code 771 * 0x78-0x7b 10-bit slave addressing 772 * 0x7c-0x7f Reserved for future purposes 773 */ 774 if (addr < 0x08 || addr > 0x77) 775 return -EINVAL; 776 return 0; 777} 778 779static int __i2c_check_addr_busy(struct device *dev, void *addrp) 780{ 781 struct i2c_client *client = i2c_verify_client(dev); 782 int addr = *(int *)addrp; 783 784 if (client && i2c_encode_flags_to_addr(client) == addr) 785 return -EBUSY; 786 return 0; 787} 788 789/* walk up mux tree */ 790static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr) 791{ 792 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); 793 int result; 794 795 result = device_for_each_child(&adapter->dev, &addr, 796 __i2c_check_addr_busy); 797 798 if (!result && parent) 799 result = i2c_check_mux_parents(parent, addr); 800 801 return result; 802} 803 804/* recurse down mux tree */ 805static int i2c_check_mux_children(struct device *dev, void *addrp) 806{ 807 int result; 808 809 if (dev->type == &i2c_adapter_type) 810 result = device_for_each_child(dev, addrp, 811 i2c_check_mux_children); 812 else 813 result = __i2c_check_addr_busy(dev, addrp); 814 815 return result; 816} 817 818static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr) 819{ 820 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); 821 int result = 0; 822 823 if (parent) 824 result = i2c_check_mux_parents(parent, addr); 825 826 if (!result) 827 result = device_for_each_child(&adapter->dev, &addr, 828 i2c_check_mux_children); 829 830 return result; 831} 832 833/** 834 * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment 835 * @adapter: Target I2C bus segment 836 * @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT 837 * locks only this branch in the adapter tree 838 */ 839static void i2c_adapter_lock_bus(struct i2c_adapter *adapter, 840 unsigned int flags) 841{ 842 rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter)); 843} 844 845/** 846 * i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment 847 * @adapter: Target I2C bus segment 848 * @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT 849 * trylocks only this branch in the adapter tree 850 */ 851static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter, 852 unsigned int flags) 853{ 854 return rt_mutex_trylock(&adapter->bus_lock); 855} 856 857/** 858 * i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment 859 * @adapter: Target I2C bus segment 860 * @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT 861 * unlocks only this branch in the adapter tree 862 */ 863static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter, 864 unsigned int flags) 865{ 866 rt_mutex_unlock(&adapter->bus_lock); 867} 868 869static void i2c_dev_set_name(struct i2c_adapter *adap, 870 struct i2c_client *client, 871 struct i2c_board_info const *info) 872{ 873 struct acpi_device *adev = ACPI_COMPANION(&client->dev); 874 875 if (info && info->dev_name) { 876 dev_set_name(&client->dev, "i2c-%s", info->dev_name); 877 return; 878 } 879 880 if (adev) { 881 dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev)); 882 return; 883 } 884 885 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap), 886 i2c_encode_flags_to_addr(client)); 887} 888 889int i2c_dev_irq_from_resources(const struct resource *resources, 890 unsigned int num_resources) 891{ 892 struct irq_data *irqd; 893 int i; 894 895 for (i = 0; i < num_resources; i++) { 896 const struct resource *r = &resources[i]; 897 898 if (resource_type(r) != IORESOURCE_IRQ) 899 continue; 900 901 if (r->flags & IORESOURCE_BITS) { 902 irqd = irq_get_irq_data(r->start); 903 if (!irqd) 904 break; 905 906 irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS); 907 } 908 909 return r->start; 910 } 911 912 return 0; 913} 914 915/** 916 * i2c_new_client_device - instantiate an i2c device 917 * @adap: the adapter managing the device 918 * @info: describes one I2C device; bus_num is ignored 919 * Context: can sleep 920 * 921 * Create an i2c device. Binding is handled through driver model 922 * probe()/remove() methods. A driver may be bound to this device when we 923 * return from this function, or any later moment (e.g. maybe hotplugging will 924 * load the driver module). This call is not appropriate for use by mainboard 925 * initialization logic, which usually runs during an arch_initcall() long 926 * before any i2c_adapter could exist. 927 * 928 * This returns the new i2c client, which may be saved for later use with 929 * i2c_unregister_device(); or an ERR_PTR to describe the error. 930 */ 931struct i2c_client * 932i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info) 933{ 934 struct i2c_client *client; 935 bool need_put = false; 936 int status; 937 938 client = kzalloc(sizeof *client, GFP_KERNEL); 939 if (!client) 940 return ERR_PTR(-ENOMEM); 941 942 client->adapter = adap; 943 944 client->dev.platform_data = info->platform_data; 945 client->flags = info->flags; 946 client->addr = info->addr; 947 948 client->init_irq = info->irq; 949 if (!client->init_irq) 950 client->init_irq = i2c_dev_irq_from_resources(info->resources, 951 info->num_resources); 952 953 strscpy(client->name, info->type, sizeof(client->name)); 954 955 status = i2c_check_addr_validity(client->addr, client->flags); 956 if (status) { 957 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n", 958 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr); 959 goto out_err_silent; 960 } 961 962 /* Check for address business */ 963 status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client)); 964 if (status) 965 goto out_err; 966 967 client->dev.parent = &client->adapter->dev; 968 client->dev.bus = &i2c_bus_type; 969 client->dev.type = &i2c_client_type; 970 client->dev.of_node = of_node_get(info->of_node); 971 client->dev.fwnode = info->fwnode; 972 973 device_enable_async_suspend(&client->dev); 974 975 if (info->swnode) { 976 status = device_add_software_node(&client->dev, info->swnode); 977 if (status) { 978 dev_err(&adap->dev, 979 "Failed to add software node to client %s: %d\n", 980 client->name, status); 981 goto out_err_put_of_node; 982 } 983 } 984 985 i2c_dev_set_name(adap, client, info); 986 status = device_register(&client->dev); 987 if (status) 988 goto out_remove_swnode; 989 990 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n", 991 client->name, dev_name(&client->dev)); 992 993 return client; 994 995out_remove_swnode: 996 device_remove_software_node(&client->dev); 997 need_put = true; 998out_err_put_of_node: 999 of_node_put(info->of_node); 1000out_err: 1001 dev_err(&adap->dev, 1002 "Failed to register i2c client %s at 0x%02x (%d)\n", 1003 client->name, client->addr, status); 1004out_err_silent: 1005 if (need_put) 1006 put_device(&client->dev); 1007 else 1008 kfree(client); 1009 return ERR_PTR(status); 1010} 1011EXPORT_SYMBOL_GPL(i2c_new_client_device); 1012 1013/** 1014 * i2c_unregister_device - reverse effect of i2c_new_*_device() 1015 * @client: value returned from i2c_new_*_device() 1016 * Context: can sleep 1017 */ 1018void i2c_unregister_device(struct i2c_client *client) 1019{ 1020 if (IS_ERR_OR_NULL(client)) 1021 return; 1022 1023 if (client->dev.of_node) { 1024 of_node_clear_flag(client->dev.of_node, OF_POPULATED); 1025 of_node_put(client->dev.of_node); 1026 } 1027 1028 if (ACPI_COMPANION(&client->dev)) 1029 acpi_device_clear_enumerated(ACPI_COMPANION(&client->dev)); 1030 device_remove_software_node(&client->dev); 1031 device_unregister(&client->dev); 1032} 1033EXPORT_SYMBOL_GPL(i2c_unregister_device); 1034 1035/** 1036 * i2c_find_device_by_fwnode() - find an i2c_client for the fwnode 1037 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_client 1038 * 1039 * Look up and return the &struct i2c_client corresponding to the @fwnode. 1040 * If no client can be found, or @fwnode is NULL, this returns NULL. 1041 * 1042 * The user must call put_device(&client->dev) once done with the i2c client. 1043 */ 1044struct i2c_client *i2c_find_device_by_fwnode(struct fwnode_handle *fwnode) 1045{ 1046 struct i2c_client *client; 1047 struct device *dev; 1048 1049 if (!fwnode) 1050 return NULL; 1051 1052 dev = bus_find_device_by_fwnode(&i2c_bus_type, fwnode); 1053 if (!dev) 1054 return NULL; 1055 1056 client = i2c_verify_client(dev); 1057 if (!client) 1058 put_device(dev); 1059 1060 return client; 1061} 1062EXPORT_SYMBOL(i2c_find_device_by_fwnode); 1063 1064 1065static const struct i2c_device_id dummy_id[] = { 1066 { "dummy", 0 }, 1067 { }, 1068}; 1069 1070static int dummy_probe(struct i2c_client *client) 1071{ 1072 return 0; 1073} 1074 1075static struct i2c_driver dummy_driver = { 1076 .driver.name = "dummy", 1077 .probe = dummy_probe, 1078 .id_table = dummy_id, 1079}; 1080 1081/** 1082 * i2c_new_dummy_device - return a new i2c device bound to a dummy driver 1083 * @adapter: the adapter managing the device 1084 * @address: seven bit address to be used 1085 * Context: can sleep 1086 * 1087 * This returns an I2C client bound to the "dummy" driver, intended for use 1088 * with devices that consume multiple addresses. Examples of such chips 1089 * include various EEPROMS (like 24c04 and 24c08 models). 1090 * 1091 * These dummy devices have two main uses. First, most I2C and SMBus calls 1092 * except i2c_transfer() need a client handle; the dummy will be that handle. 1093 * And second, this prevents the specified address from being bound to a 1094 * different driver. 1095 * 1096 * This returns the new i2c client, which should be saved for later use with 1097 * i2c_unregister_device(); or an ERR_PTR to describe the error. 1098 */ 1099struct i2c_client *i2c_new_dummy_device(struct i2c_adapter *adapter, u16 address) 1100{ 1101 struct i2c_board_info info = { 1102 I2C_BOARD_INFO("dummy", address), 1103 }; 1104 1105 return i2c_new_client_device(adapter, &info); 1106} 1107EXPORT_SYMBOL_GPL(i2c_new_dummy_device); 1108 1109static void devm_i2c_release_dummy(void *client) 1110{ 1111 i2c_unregister_device(client); 1112} 1113 1114/** 1115 * devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver 1116 * @dev: device the managed resource is bound to 1117 * @adapter: the adapter managing the device 1118 * @address: seven bit address to be used 1119 * Context: can sleep 1120 * 1121 * This is the device-managed version of @i2c_new_dummy_device. It returns the 1122 * new i2c client or an ERR_PTR in case of an error. 1123 */ 1124struct i2c_client *devm_i2c_new_dummy_device(struct device *dev, 1125 struct i2c_adapter *adapter, 1126 u16 address) 1127{ 1128 struct i2c_client *client; 1129 int ret; 1130 1131 client = i2c_new_dummy_device(adapter, address); 1132 if (IS_ERR(client)) 1133 return client; 1134 1135 ret = devm_add_action_or_reset(dev, devm_i2c_release_dummy, client); 1136 if (ret) 1137 return ERR_PTR(ret); 1138 1139 return client; 1140} 1141EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device); 1142 1143/** 1144 * i2c_new_ancillary_device - Helper to get the instantiated secondary address 1145 * and create the associated device 1146 * @client: Handle to the primary client 1147 * @name: Handle to specify which secondary address to get 1148 * @default_addr: Used as a fallback if no secondary address was specified 1149 * Context: can sleep 1150 * 1151 * I2C clients can be composed of multiple I2C slaves bound together in a single 1152 * component. The I2C client driver then binds to the master I2C slave and needs 1153 * to create I2C dummy clients to communicate with all the other slaves. 1154 * 1155 * This function creates and returns an I2C dummy client whose I2C address is 1156 * retrieved from the platform firmware based on the given slave name. If no 1157 * address is specified by the firmware default_addr is used. 1158 * 1159 * On DT-based platforms the address is retrieved from the "reg" property entry 1160 * cell whose "reg-names" value matches the slave name. 1161 * 1162 * This returns the new i2c client, which should be saved for later use with 1163 * i2c_unregister_device(); or an ERR_PTR to describe the error. 1164 */ 1165struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client, 1166 const char *name, 1167 u16 default_addr) 1168{ 1169 struct device_node *np = client->dev.of_node; 1170 u32 addr = default_addr; 1171 int i; 1172 1173 if (np) { 1174 i = of_property_match_string(np, "reg-names", name); 1175 if (i >= 0) 1176 of_property_read_u32_index(np, "reg", i, &addr); 1177 } 1178 1179 dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr); 1180 return i2c_new_dummy_device(client->adapter, addr); 1181} 1182EXPORT_SYMBOL_GPL(i2c_new_ancillary_device); 1183 1184/* ------------------------------------------------------------------------- */ 1185 1186/* I2C bus adapters -- one roots each I2C or SMBUS segment */ 1187 1188static void i2c_adapter_dev_release(struct device *dev) 1189{ 1190 struct i2c_adapter *adap = to_i2c_adapter(dev); 1191 complete(&adap->dev_released); 1192} 1193 1194unsigned int i2c_adapter_depth(struct i2c_adapter *adapter) 1195{ 1196 unsigned int depth = 0; 1197 1198 while ((adapter = i2c_parent_is_i2c_adapter(adapter))) 1199 depth++; 1200 1201 WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES, 1202 "adapter depth exceeds lockdep subclass limit\n"); 1203 1204 return depth; 1205} 1206EXPORT_SYMBOL_GPL(i2c_adapter_depth); 1207 1208/* 1209 * Let users instantiate I2C devices through sysfs. This can be used when 1210 * platform initialization code doesn't contain the proper data for 1211 * whatever reason. Also useful for drivers that do device detection and 1212 * detection fails, either because the device uses an unexpected address, 1213 * or this is a compatible device with different ID register values. 1214 * 1215 * Parameter checking may look overzealous, but we really don't want 1216 * the user to provide incorrect parameters. 1217 */ 1218static ssize_t 1219new_device_store(struct device *dev, struct device_attribute *attr, 1220 const char *buf, size_t count) 1221{ 1222 struct i2c_adapter *adap = to_i2c_adapter(dev); 1223 struct i2c_board_info info; 1224 struct i2c_client *client; 1225 char *blank, end; 1226 int res; 1227 1228 memset(&info, 0, sizeof(struct i2c_board_info)); 1229 1230 blank = strchr(buf, ' '); 1231 if (!blank) { 1232 dev_err(dev, "%s: Missing parameters\n", "new_device"); 1233 return -EINVAL; 1234 } 1235 if (blank - buf > I2C_NAME_SIZE - 1) { 1236 dev_err(dev, "%s: Invalid device name\n", "new_device"); 1237 return -EINVAL; 1238 } 1239 memcpy(info.type, buf, blank - buf); 1240 1241 /* Parse remaining parameters, reject extra parameters */ 1242 res = sscanf(++blank, "%hi%c", &info.addr, &end); 1243 if (res < 1) { 1244 dev_err(dev, "%s: Can't parse I2C address\n", "new_device"); 1245 return -EINVAL; 1246 } 1247 if (res > 1 && end != '\n') { 1248 dev_err(dev, "%s: Extra parameters\n", "new_device"); 1249 return -EINVAL; 1250 } 1251 1252 if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) { 1253 info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT; 1254 info.flags |= I2C_CLIENT_TEN; 1255 } 1256 1257 if (info.addr & I2C_ADDR_OFFSET_SLAVE) { 1258 info.addr &= ~I2C_ADDR_OFFSET_SLAVE; 1259 info.flags |= I2C_CLIENT_SLAVE; 1260 } 1261 1262 client = i2c_new_client_device(adap, &info); 1263 if (IS_ERR(client)) 1264 return PTR_ERR(client); 1265 1266 /* Keep track of the added device */ 1267 mutex_lock(&adap->userspace_clients_lock); 1268 list_add_tail(&client->detected, &adap->userspace_clients); 1269 mutex_unlock(&adap->userspace_clients_lock); 1270 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device", 1271 info.type, info.addr); 1272 1273 return count; 1274} 1275static DEVICE_ATTR_WO(new_device); 1276 1277/* 1278 * And of course let the users delete the devices they instantiated, if 1279 * they got it wrong. This interface can only be used to delete devices 1280 * instantiated by i2c_sysfs_new_device above. This guarantees that we 1281 * don't delete devices to which some kernel code still has references. 1282 * 1283 * Parameter checking may look overzealous, but we really don't want 1284 * the user to delete the wrong device. 1285 */ 1286static ssize_t 1287delete_device_store(struct device *dev, struct device_attribute *attr, 1288 const char *buf, size_t count) 1289{ 1290 struct i2c_adapter *adap = to_i2c_adapter(dev); 1291 struct i2c_client *client, *next; 1292 unsigned short addr; 1293 char end; 1294 int res; 1295 1296 /* Parse parameters, reject extra parameters */ 1297 res = sscanf(buf, "%hi%c", &addr, &end); 1298 if (res < 1) { 1299 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device"); 1300 return -EINVAL; 1301 } 1302 if (res > 1 && end != '\n') { 1303 dev_err(dev, "%s: Extra parameters\n", "delete_device"); 1304 return -EINVAL; 1305 } 1306 1307 /* Make sure the device was added through sysfs */ 1308 res = -ENOENT; 1309 mutex_lock_nested(&adap->userspace_clients_lock, 1310 i2c_adapter_depth(adap)); 1311 list_for_each_entry_safe(client, next, &adap->userspace_clients, 1312 detected) { 1313 if (i2c_encode_flags_to_addr(client) == addr) { 1314 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n", 1315 "delete_device", client->name, client->addr); 1316 1317 list_del(&client->detected); 1318 i2c_unregister_device(client); 1319 res = count; 1320 break; 1321 } 1322 } 1323 mutex_unlock(&adap->userspace_clients_lock); 1324 1325 if (res < 0) 1326 dev_err(dev, "%s: Can't find device in list\n", 1327 "delete_device"); 1328 return res; 1329} 1330static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL, 1331 delete_device_store); 1332 1333static struct attribute *i2c_adapter_attrs[] = { 1334 &dev_attr_name.attr, 1335 &dev_attr_new_device.attr, 1336 &dev_attr_delete_device.attr, 1337 NULL 1338}; 1339ATTRIBUTE_GROUPS(i2c_adapter); 1340 1341struct device_type i2c_adapter_type = { 1342 .groups = i2c_adapter_groups, 1343 .release = i2c_adapter_dev_release, 1344}; 1345EXPORT_SYMBOL_GPL(i2c_adapter_type); 1346 1347/** 1348 * i2c_verify_adapter - return parameter as i2c_adapter or NULL 1349 * @dev: device, probably from some driver model iterator 1350 * 1351 * When traversing the driver model tree, perhaps using driver model 1352 * iterators like @device_for_each_child(), you can't assume very much 1353 * about the nodes you find. Use this function to avoid oopses caused 1354 * by wrongly treating some non-I2C device as an i2c_adapter. 1355 */ 1356struct i2c_adapter *i2c_verify_adapter(struct device *dev) 1357{ 1358 return (dev->type == &i2c_adapter_type) 1359 ? to_i2c_adapter(dev) 1360 : NULL; 1361} 1362EXPORT_SYMBOL(i2c_verify_adapter); 1363 1364#ifdef CONFIG_I2C_COMPAT 1365static struct class_compat *i2c_adapter_compat_class; 1366#endif 1367 1368static void i2c_scan_static_board_info(struct i2c_adapter *adapter) 1369{ 1370 struct i2c_devinfo *devinfo; 1371 1372 down_read(&__i2c_board_lock); 1373 list_for_each_entry(devinfo, &__i2c_board_list, list) { 1374 if (devinfo->busnum == adapter->nr && 1375 IS_ERR(i2c_new_client_device(adapter, &devinfo->board_info))) 1376 dev_err(&adapter->dev, 1377 "Can't create device at 0x%02x\n", 1378 devinfo->board_info.addr); 1379 } 1380 up_read(&__i2c_board_lock); 1381} 1382 1383static int i2c_do_add_adapter(struct i2c_driver *driver, 1384 struct i2c_adapter *adap) 1385{ 1386 /* Detect supported devices on that bus, and instantiate them */ 1387 i2c_detect(adap, driver); 1388 1389 return 0; 1390} 1391 1392static int __process_new_adapter(struct device_driver *d, void *data) 1393{ 1394 return i2c_do_add_adapter(to_i2c_driver(d), data); 1395} 1396 1397static const struct i2c_lock_operations i2c_adapter_lock_ops = { 1398 .lock_bus = i2c_adapter_lock_bus, 1399 .trylock_bus = i2c_adapter_trylock_bus, 1400 .unlock_bus = i2c_adapter_unlock_bus, 1401}; 1402 1403static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap) 1404{ 1405 struct irq_domain *domain = adap->host_notify_domain; 1406 irq_hw_number_t hwirq; 1407 1408 if (!domain) 1409 return; 1410 1411 for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++) 1412 irq_dispose_mapping(irq_find_mapping(domain, hwirq)); 1413 1414 irq_domain_remove(domain); 1415 adap->host_notify_domain = NULL; 1416} 1417 1418static int i2c_host_notify_irq_map(struct irq_domain *h, 1419 unsigned int virq, 1420 irq_hw_number_t hw_irq_num) 1421{ 1422 irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq); 1423 1424 return 0; 1425} 1426 1427static const struct irq_domain_ops i2c_host_notify_irq_ops = { 1428 .map = i2c_host_notify_irq_map, 1429}; 1430 1431static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap) 1432{ 1433 struct irq_domain *domain; 1434 1435 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY)) 1436 return 0; 1437 1438 domain = irq_domain_create_linear(adap->dev.parent->fwnode, 1439 I2C_ADDR_7BITS_COUNT, 1440 &i2c_host_notify_irq_ops, adap); 1441 if (!domain) 1442 return -ENOMEM; 1443 1444 adap->host_notify_domain = domain; 1445 1446 return 0; 1447} 1448 1449/** 1450 * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct 1451 * I2C client. 1452 * @adap: the adapter 1453 * @addr: the I2C address of the notifying device 1454 * Context: can't sleep 1455 * 1456 * Helper function to be called from an I2C bus driver's interrupt 1457 * handler. It will schedule the Host Notify IRQ. 1458 */ 1459int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr) 1460{ 1461 int irq; 1462 1463 if (!adap) 1464 return -EINVAL; 1465 1466 irq = irq_find_mapping(adap->host_notify_domain, addr); 1467 if (irq <= 0) 1468 return -ENXIO; 1469 1470 generic_handle_irq_safe(irq); 1471 1472 return 0; 1473} 1474EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify); 1475 1476static int i2c_register_adapter(struct i2c_adapter *adap) 1477{ 1478 int res = -EINVAL; 1479 1480 /* Can't register until after driver model init */ 1481 if (WARN_ON(!is_registered)) { 1482 res = -EAGAIN; 1483 goto out_list; 1484 } 1485 1486 /* Sanity checks */ 1487 if (WARN(!adap->name[0], "i2c adapter has no name")) 1488 goto out_list; 1489 1490 if (!adap->algo) { 1491 pr_err("adapter '%s': no algo supplied!\n", adap->name); 1492 goto out_list; 1493 } 1494 1495 if (!adap->lock_ops) 1496 adap->lock_ops = &i2c_adapter_lock_ops; 1497 1498 adap->locked_flags = 0; 1499 rt_mutex_init(&adap->bus_lock); 1500 rt_mutex_init(&adap->mux_lock); 1501 mutex_init(&adap->userspace_clients_lock); 1502 INIT_LIST_HEAD(&adap->userspace_clients); 1503 1504 /* Set default timeout to 1 second if not already set */ 1505 if (adap->timeout == 0) 1506 adap->timeout = HZ; 1507 1508 /* register soft irqs for Host Notify */ 1509 res = i2c_setup_host_notify_irq_domain(adap); 1510 if (res) { 1511 pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n", 1512 adap->name, res); 1513 goto out_list; 1514 } 1515 1516 dev_set_name(&adap->dev, "i2c-%d", adap->nr); 1517 adap->dev.bus = &i2c_bus_type; 1518 adap->dev.type = &i2c_adapter_type; 1519 res = device_register(&adap->dev); 1520 if (res) { 1521 pr_err("adapter '%s': can't register device (%d)\n", adap->name, res); 1522 goto out_list; 1523 } 1524 1525 res = i2c_setup_smbus_alert(adap); 1526 if (res) 1527 goto out_reg; 1528 1529 device_enable_async_suspend(&adap->dev); 1530 pm_runtime_no_callbacks(&adap->dev); 1531 pm_suspend_ignore_children(&adap->dev, true); 1532 pm_runtime_enable(&adap->dev); 1533 1534 res = i2c_init_recovery(adap); 1535 if (res == -EPROBE_DEFER) 1536 goto out_reg; 1537 1538 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name); 1539 1540#ifdef CONFIG_I2C_COMPAT 1541 res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev, 1542 adap->dev.parent); 1543 if (res) 1544 dev_warn(&adap->dev, 1545 "Failed to create compatibility class link\n"); 1546#endif 1547 1548 /* create pre-declared device nodes */ 1549 of_i2c_register_devices(adap); 1550 i2c_acpi_install_space_handler(adap); 1551 i2c_acpi_register_devices(adap); 1552 1553 if (adap->nr < __i2c_first_dynamic_bus_num) 1554 i2c_scan_static_board_info(adap); 1555 1556 /* Notify drivers */ 1557 mutex_lock(&core_lock); 1558 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter); 1559 mutex_unlock(&core_lock); 1560 1561 return 0; 1562 1563out_reg: 1564 init_completion(&adap->dev_released); 1565 device_unregister(&adap->dev); 1566 wait_for_completion(&adap->dev_released); 1567out_list: 1568 mutex_lock(&core_lock); 1569 idr_remove(&i2c_adapter_idr, adap->nr); 1570 mutex_unlock(&core_lock); 1571 return res; 1572} 1573 1574/** 1575 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1 1576 * @adap: the adapter to register (with adap->nr initialized) 1577 * Context: can sleep 1578 * 1579 * See i2c_add_numbered_adapter() for details. 1580 */ 1581static int __i2c_add_numbered_adapter(struct i2c_adapter *adap) 1582{ 1583 int id; 1584 1585 mutex_lock(&core_lock); 1586 id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL); 1587 mutex_unlock(&core_lock); 1588 if (WARN(id < 0, "couldn't get idr")) 1589 return id == -ENOSPC ? -EBUSY : id; 1590 1591 return i2c_register_adapter(adap); 1592} 1593 1594/** 1595 * i2c_add_adapter - declare i2c adapter, use dynamic bus number 1596 * @adapter: the adapter to add 1597 * Context: can sleep 1598 * 1599 * This routine is used to declare an I2C adapter when its bus number 1600 * doesn't matter or when its bus number is specified by an dt alias. 1601 * Examples of bases when the bus number doesn't matter: I2C adapters 1602 * dynamically added by USB links or PCI plugin cards. 1603 * 1604 * When this returns zero, a new bus number was allocated and stored 1605 * in adap->nr, and the specified adapter became available for clients. 1606 * Otherwise, a negative errno value is returned. 1607 */ 1608int i2c_add_adapter(struct i2c_adapter *adapter) 1609{ 1610 struct device *dev = &adapter->dev; 1611 int id; 1612 1613 if (dev->of_node) { 1614 id = of_alias_get_id(dev->of_node, "i2c"); 1615 if (id >= 0) { 1616 adapter->nr = id; 1617 return __i2c_add_numbered_adapter(adapter); 1618 } 1619 } 1620 1621 mutex_lock(&core_lock); 1622 id = idr_alloc(&i2c_adapter_idr, adapter, 1623 __i2c_first_dynamic_bus_num, 0, GFP_KERNEL); 1624 mutex_unlock(&core_lock); 1625 if (WARN(id < 0, "couldn't get idr")) 1626 return id; 1627 1628 adapter->nr = id; 1629 1630 return i2c_register_adapter(adapter); 1631} 1632EXPORT_SYMBOL(i2c_add_adapter); 1633 1634/** 1635 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number 1636 * @adap: the adapter to register (with adap->nr initialized) 1637 * Context: can sleep 1638 * 1639 * This routine is used to declare an I2C adapter when its bus number 1640 * matters. For example, use it for I2C adapters from system-on-chip CPUs, 1641 * or otherwise built in to the system's mainboard, and where i2c_board_info 1642 * is used to properly configure I2C devices. 1643 * 1644 * If the requested bus number is set to -1, then this function will behave 1645 * identically to i2c_add_adapter, and will dynamically assign a bus number. 1646 * 1647 * If no devices have pre-been declared for this bus, then be sure to 1648 * register the adapter before any dynamically allocated ones. Otherwise 1649 * the required bus ID may not be available. 1650 * 1651 * When this returns zero, the specified adapter became available for 1652 * clients using the bus number provided in adap->nr. Also, the table 1653 * of I2C devices pre-declared using i2c_register_board_info() is scanned, 1654 * and the appropriate driver model device nodes are created. Otherwise, a 1655 * negative errno value is returned. 1656 */ 1657int i2c_add_numbered_adapter(struct i2c_adapter *adap) 1658{ 1659 if (adap->nr == -1) /* -1 means dynamically assign bus id */ 1660 return i2c_add_adapter(adap); 1661 1662 return __i2c_add_numbered_adapter(adap); 1663} 1664EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter); 1665 1666static void i2c_do_del_adapter(struct i2c_driver *driver, 1667 struct i2c_adapter *adapter) 1668{ 1669 struct i2c_client *client, *_n; 1670 1671 /* Remove the devices we created ourselves as the result of hardware 1672 * probing (using a driver's detect method) */ 1673 list_for_each_entry_safe(client, _n, &driver->clients, detected) { 1674 if (client->adapter == adapter) { 1675 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n", 1676 client->name, client->addr); 1677 list_del(&client->detected); 1678 i2c_unregister_device(client); 1679 } 1680 } 1681} 1682 1683static int __unregister_client(struct device *dev, void *dummy) 1684{ 1685 struct i2c_client *client = i2c_verify_client(dev); 1686 if (client && strcmp(client->name, "dummy")) 1687 i2c_unregister_device(client); 1688 return 0; 1689} 1690 1691static int __unregister_dummy(struct device *dev, void *dummy) 1692{ 1693 struct i2c_client *client = i2c_verify_client(dev); 1694 i2c_unregister_device(client); 1695 return 0; 1696} 1697 1698static int __process_removed_adapter(struct device_driver *d, void *data) 1699{ 1700 i2c_do_del_adapter(to_i2c_driver(d), data); 1701 return 0; 1702} 1703 1704/** 1705 * i2c_del_adapter - unregister I2C adapter 1706 * @adap: the adapter being unregistered 1707 * Context: can sleep 1708 * 1709 * This unregisters an I2C adapter which was previously registered 1710 * by @i2c_add_adapter or @i2c_add_numbered_adapter. 1711 */ 1712void i2c_del_adapter(struct i2c_adapter *adap) 1713{ 1714 struct i2c_adapter *found; 1715 struct i2c_client *client, *next; 1716 1717 /* First make sure that this adapter was ever added */ 1718 mutex_lock(&core_lock); 1719 found = idr_find(&i2c_adapter_idr, adap->nr); 1720 mutex_unlock(&core_lock); 1721 if (found != adap) { 1722 pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name); 1723 return; 1724 } 1725 1726 i2c_acpi_remove_space_handler(adap); 1727 /* Tell drivers about this removal */ 1728 mutex_lock(&core_lock); 1729 bus_for_each_drv(&i2c_bus_type, NULL, adap, 1730 __process_removed_adapter); 1731 mutex_unlock(&core_lock); 1732 1733 /* Remove devices instantiated from sysfs */ 1734 mutex_lock_nested(&adap->userspace_clients_lock, 1735 i2c_adapter_depth(adap)); 1736 list_for_each_entry_safe(client, next, &adap->userspace_clients, 1737 detected) { 1738 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name, 1739 client->addr); 1740 list_del(&client->detected); 1741 i2c_unregister_device(client); 1742 } 1743 mutex_unlock(&adap->userspace_clients_lock); 1744 1745 /* Detach any active clients. This can't fail, thus we do not 1746 * check the returned value. This is a two-pass process, because 1747 * we can't remove the dummy devices during the first pass: they 1748 * could have been instantiated by real devices wishing to clean 1749 * them up properly, so we give them a chance to do that first. */ 1750 device_for_each_child(&adap->dev, NULL, __unregister_client); 1751 device_for_each_child(&adap->dev, NULL, __unregister_dummy); 1752 1753#ifdef CONFIG_I2C_COMPAT 1754 class_compat_remove_link(i2c_adapter_compat_class, &adap->dev, 1755 adap->dev.parent); 1756#endif 1757 1758 /* device name is gone after device_unregister */ 1759 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name); 1760 1761 pm_runtime_disable(&adap->dev); 1762 1763 i2c_host_notify_irq_teardown(adap); 1764 1765 /* wait until all references to the device are gone 1766 * 1767 * FIXME: This is old code and should ideally be replaced by an 1768 * alternative which results in decoupling the lifetime of the struct 1769 * device from the i2c_adapter, like spi or netdev do. Any solution 1770 * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled! 1771 */ 1772 init_completion(&adap->dev_released); 1773 device_unregister(&adap->dev); 1774 wait_for_completion(&adap->dev_released); 1775 1776 /* free bus id */ 1777 mutex_lock(&core_lock); 1778 idr_remove(&i2c_adapter_idr, adap->nr); 1779 mutex_unlock(&core_lock); 1780 1781 /* Clear the device structure in case this adapter is ever going to be 1782 added again */ 1783 memset(&adap->dev, 0, sizeof(adap->dev)); 1784} 1785EXPORT_SYMBOL(i2c_del_adapter); 1786 1787static void devm_i2c_del_adapter(void *adapter) 1788{ 1789 i2c_del_adapter(adapter); 1790} 1791 1792/** 1793 * devm_i2c_add_adapter - device-managed variant of i2c_add_adapter() 1794 * @dev: managing device for adding this I2C adapter 1795 * @adapter: the adapter to add 1796 * Context: can sleep 1797 * 1798 * Add adapter with dynamic bus number, same with i2c_add_adapter() 1799 * but the adapter will be auto deleted on driver detach. 1800 */ 1801int devm_i2c_add_adapter(struct device *dev, struct i2c_adapter *adapter) 1802{ 1803 int ret; 1804 1805 ret = i2c_add_adapter(adapter); 1806 if (ret) 1807 return ret; 1808 1809 return devm_add_action_or_reset(dev, devm_i2c_del_adapter, adapter); 1810} 1811EXPORT_SYMBOL_GPL(devm_i2c_add_adapter); 1812 1813static int i2c_dev_or_parent_fwnode_match(struct device *dev, const void *data) 1814{ 1815 if (dev_fwnode(dev) == data) 1816 return 1; 1817 1818 if (dev->parent && dev_fwnode(dev->parent) == data) 1819 return 1; 1820 1821 return 0; 1822} 1823 1824/** 1825 * i2c_find_adapter_by_fwnode() - find an i2c_adapter for the fwnode 1826 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter 1827 * 1828 * Look up and return the &struct i2c_adapter corresponding to the @fwnode. 1829 * If no adapter can be found, or @fwnode is NULL, this returns NULL. 1830 * 1831 * The user must call put_device(&adapter->dev) once done with the i2c adapter. 1832 */ 1833struct i2c_adapter *i2c_find_adapter_by_fwnode(struct fwnode_handle *fwnode) 1834{ 1835 struct i2c_adapter *adapter; 1836 struct device *dev; 1837 1838 if (!fwnode) 1839 return NULL; 1840 1841 dev = bus_find_device(&i2c_bus_type, NULL, fwnode, 1842 i2c_dev_or_parent_fwnode_match); 1843 if (!dev) 1844 return NULL; 1845 1846 adapter = i2c_verify_adapter(dev); 1847 if (!adapter) 1848 put_device(dev); 1849 1850 return adapter; 1851} 1852EXPORT_SYMBOL(i2c_find_adapter_by_fwnode); 1853 1854/** 1855 * i2c_get_adapter_by_fwnode() - find an i2c_adapter for the fwnode 1856 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter 1857 * 1858 * Look up and return the &struct i2c_adapter corresponding to the @fwnode, 1859 * and increment the adapter module's use count. If no adapter can be found, 1860 * or @fwnode is NULL, this returns NULL. 1861 * 1862 * The user must call i2c_put_adapter(adapter) once done with the i2c adapter. 1863 * Note that this is different from i2c_find_adapter_by_node(). 1864 */ 1865struct i2c_adapter *i2c_get_adapter_by_fwnode(struct fwnode_handle *fwnode) 1866{ 1867 struct i2c_adapter *adapter; 1868 1869 adapter = i2c_find_adapter_by_fwnode(fwnode); 1870 if (!adapter) 1871 return NULL; 1872 1873 if (!try_module_get(adapter->owner)) { 1874 put_device(&adapter->dev); 1875 adapter = NULL; 1876 } 1877 1878 return adapter; 1879} 1880EXPORT_SYMBOL(i2c_get_adapter_by_fwnode); 1881 1882static void i2c_parse_timing(struct device *dev, char *prop_name, u32 *cur_val_p, 1883 u32 def_val, bool use_def) 1884{ 1885 int ret; 1886 1887 ret = device_property_read_u32(dev, prop_name, cur_val_p); 1888 if (ret && use_def) 1889 *cur_val_p = def_val; 1890 1891 dev_dbg(dev, "%s: %u\n", prop_name, *cur_val_p); 1892} 1893 1894/** 1895 * i2c_parse_fw_timings - get I2C related timing parameters from firmware 1896 * @dev: The device to scan for I2C timing properties 1897 * @t: the i2c_timings struct to be filled with values 1898 * @use_defaults: bool to use sane defaults derived from the I2C specification 1899 * when properties are not found, otherwise don't update 1900 * 1901 * Scan the device for the generic I2C properties describing timing parameters 1902 * for the signal and fill the given struct with the results. If a property was 1903 * not found and use_defaults was true, then maximum timings are assumed which 1904 * are derived from the I2C specification. If use_defaults is not used, the 1905 * results will be as before, so drivers can apply their own defaults before 1906 * calling this helper. The latter is mainly intended for avoiding regressions 1907 * of existing drivers which want to switch to this function. New drivers 1908 * almost always should use the defaults. 1909 */ 1910void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults) 1911{ 1912 bool u = use_defaults; 1913 u32 d; 1914 1915 i2c_parse_timing(dev, "clock-frequency", &t->bus_freq_hz, 1916 I2C_MAX_STANDARD_MODE_FREQ, u); 1917 1918 d = t->bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ ? 1000 : 1919 t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120; 1920 i2c_parse_timing(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns, d, u); 1921 1922 d = t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120; 1923 i2c_parse_timing(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns, d, u); 1924 1925 i2c_parse_timing(dev, "i2c-scl-internal-delay-ns", 1926 &t->scl_int_delay_ns, 0, u); 1927 i2c_parse_timing(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns, 1928 t->scl_fall_ns, u); 1929 i2c_parse_timing(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns, 0, u); 1930 i2c_parse_timing(dev, "i2c-digital-filter-width-ns", 1931 &t->digital_filter_width_ns, 0, u); 1932 i2c_parse_timing(dev, "i2c-analog-filter-cutoff-frequency", 1933 &t->analog_filter_cutoff_freq_hz, 0, u); 1934} 1935EXPORT_SYMBOL_GPL(i2c_parse_fw_timings); 1936 1937/* ------------------------------------------------------------------------- */ 1938 1939int i2c_for_each_dev(void *data, int (*fn)(struct device *dev, void *data)) 1940{ 1941 int res; 1942 1943 mutex_lock(&core_lock); 1944 res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn); 1945 mutex_unlock(&core_lock); 1946 1947 return res; 1948} 1949EXPORT_SYMBOL_GPL(i2c_for_each_dev); 1950 1951static int __process_new_driver(struct device *dev, void *data) 1952{ 1953 if (dev->type != &i2c_adapter_type) 1954 return 0; 1955 return i2c_do_add_adapter(data, to_i2c_adapter(dev)); 1956} 1957 1958/* 1959 * An i2c_driver is used with one or more i2c_client (device) nodes to access 1960 * i2c slave chips, on a bus instance associated with some i2c_adapter. 1961 */ 1962 1963int i2c_register_driver(struct module *owner, struct i2c_driver *driver) 1964{ 1965 int res; 1966 1967 /* Can't register until after driver model init */ 1968 if (WARN_ON(!is_registered)) 1969 return -EAGAIN; 1970 1971 /* add the driver to the list of i2c drivers in the driver core */ 1972 driver->driver.owner = owner; 1973 driver->driver.bus = &i2c_bus_type; 1974 INIT_LIST_HEAD(&driver->clients); 1975 1976 /* When registration returns, the driver core 1977 * will have called probe() for all matching-but-unbound devices. 1978 */ 1979 res = driver_register(&driver->driver); 1980 if (res) 1981 return res; 1982 1983 pr_debug("driver [%s] registered\n", driver->driver.name); 1984 1985 /* Walk the adapters that are already present */ 1986 i2c_for_each_dev(driver, __process_new_driver); 1987 1988 return 0; 1989} 1990EXPORT_SYMBOL(i2c_register_driver); 1991 1992static int __process_removed_driver(struct device *dev, void *data) 1993{ 1994 if (dev->type == &i2c_adapter_type) 1995 i2c_do_del_adapter(data, to_i2c_adapter(dev)); 1996 return 0; 1997} 1998 1999/** 2000 * i2c_del_driver - unregister I2C driver 2001 * @driver: the driver being unregistered 2002 * Context: can sleep 2003 */ 2004void i2c_del_driver(struct i2c_driver *driver) 2005{ 2006 i2c_for_each_dev(driver, __process_removed_driver); 2007 2008 driver_unregister(&driver->driver); 2009 pr_debug("driver [%s] unregistered\n", driver->driver.name); 2010} 2011EXPORT_SYMBOL(i2c_del_driver); 2012 2013/* ------------------------------------------------------------------------- */ 2014 2015struct i2c_cmd_arg { 2016 unsigned cmd; 2017 void *arg; 2018}; 2019 2020static int i2c_cmd(struct device *dev, void *_arg) 2021{ 2022 struct i2c_client *client = i2c_verify_client(dev); 2023 struct i2c_cmd_arg *arg = _arg; 2024 struct i2c_driver *driver; 2025 2026 if (!client || !client->dev.driver) 2027 return 0; 2028 2029 driver = to_i2c_driver(client->dev.driver); 2030 if (driver->command) 2031 driver->command(client, arg->cmd, arg->arg); 2032 return 0; 2033} 2034 2035void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg) 2036{ 2037 struct i2c_cmd_arg cmd_arg; 2038 2039 cmd_arg.cmd = cmd; 2040 cmd_arg.arg = arg; 2041 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd); 2042} 2043EXPORT_SYMBOL(i2c_clients_command); 2044 2045static int __init i2c_init(void) 2046{ 2047 int retval; 2048 2049 retval = of_alias_get_highest_id("i2c"); 2050 2051 down_write(&__i2c_board_lock); 2052 if (retval >= __i2c_first_dynamic_bus_num) 2053 __i2c_first_dynamic_bus_num = retval + 1; 2054 up_write(&__i2c_board_lock); 2055 2056 retval = bus_register(&i2c_bus_type); 2057 if (retval) 2058 return retval; 2059 2060 is_registered = true; 2061 2062#ifdef CONFIG_I2C_COMPAT 2063 i2c_adapter_compat_class = class_compat_register("i2c-adapter"); 2064 if (!i2c_adapter_compat_class) { 2065 retval = -ENOMEM; 2066 goto bus_err; 2067 } 2068#endif 2069 retval = i2c_add_driver(&dummy_driver); 2070 if (retval) 2071 goto class_err; 2072 2073 if (IS_ENABLED(CONFIG_OF_DYNAMIC)) 2074 WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier)); 2075 if (IS_ENABLED(CONFIG_ACPI)) 2076 WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier)); 2077 2078 return 0; 2079 2080class_err: 2081#ifdef CONFIG_I2C_COMPAT 2082 class_compat_unregister(i2c_adapter_compat_class); 2083bus_err: 2084#endif 2085 is_registered = false; 2086 bus_unregister(&i2c_bus_type); 2087 return retval; 2088} 2089 2090static void __exit i2c_exit(void) 2091{ 2092 if (IS_ENABLED(CONFIG_ACPI)) 2093 WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier)); 2094 if (IS_ENABLED(CONFIG_OF_DYNAMIC)) 2095 WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier)); 2096 i2c_del_driver(&dummy_driver); 2097#ifdef CONFIG_I2C_COMPAT 2098 class_compat_unregister(i2c_adapter_compat_class); 2099#endif 2100 bus_unregister(&i2c_bus_type); 2101 tracepoint_synchronize_unregister(); 2102} 2103 2104/* We must initialize early, because some subsystems register i2c drivers 2105 * in subsys_initcall() code, but are linked (and initialized) before i2c. 2106 */ 2107postcore_initcall(i2c_init); 2108module_exit(i2c_exit); 2109 2110/* ---------------------------------------------------- 2111 * the functional interface to the i2c busses. 2112 * ---------------------------------------------------- 2113 */ 2114 2115/* Check if val is exceeding the quirk IFF quirk is non 0 */ 2116#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk))) 2117 2118static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg) 2119{ 2120 dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n", 2121 err_msg, msg->addr, msg->len, 2122 msg->flags & I2C_M_RD ? "read" : "write"); 2123 return -EOPNOTSUPP; 2124} 2125 2126static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 2127{ 2128 const struct i2c_adapter_quirks *q = adap->quirks; 2129 int max_num = q->max_num_msgs, i; 2130 bool do_len_check = true; 2131 2132 if (q->flags & I2C_AQ_COMB) { 2133 max_num = 2; 2134 2135 /* special checks for combined messages */ 2136 if (num == 2) { 2137 if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD) 2138 return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write"); 2139 2140 if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD)) 2141 return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read"); 2142 2143 if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr) 2144 return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr"); 2145 2146 if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len)) 2147 return i2c_quirk_error(adap, &msgs[0], "msg too long"); 2148 2149 if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len)) 2150 return i2c_quirk_error(adap, &msgs[1], "msg too long"); 2151 2152 do_len_check = false; 2153 } 2154 } 2155 2156 if (i2c_quirk_exceeded(num, max_num)) 2157 return i2c_quirk_error(adap, &msgs[0], "too many messages"); 2158 2159 for (i = 0; i < num; i++) { 2160 u16 len = msgs[i].len; 2161 2162 if (msgs[i].flags & I2C_M_RD) { 2163 if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len)) 2164 return i2c_quirk_error(adap, &msgs[i], "msg too long"); 2165 2166 if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0) 2167 return i2c_quirk_error(adap, &msgs[i], "no zero length"); 2168 } else { 2169 if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len)) 2170 return i2c_quirk_error(adap, &msgs[i], "msg too long"); 2171 2172 if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0) 2173 return i2c_quirk_error(adap, &msgs[i], "no zero length"); 2174 } 2175 } 2176 2177 return 0; 2178} 2179 2180/** 2181 * __i2c_transfer - unlocked flavor of i2c_transfer 2182 * @adap: Handle to I2C bus 2183 * @msgs: One or more messages to execute before STOP is issued to 2184 * terminate the operation; each message begins with a START. 2185 * @num: Number of messages to be executed. 2186 * 2187 * Returns negative errno, else the number of messages executed. 2188 * 2189 * Adapter lock must be held when calling this function. No debug logging 2190 * takes place. adap->algo->master_xfer existence isn't checked. 2191 */ 2192int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 2193{ 2194 unsigned long orig_jiffies; 2195 int ret, try; 2196 2197 if (WARN_ON(!msgs || num < 1)) 2198 return -EINVAL; 2199 2200 ret = __i2c_check_suspended(adap); 2201 if (ret) 2202 return ret; 2203 2204 if (adap->quirks && i2c_check_for_quirks(adap, msgs, num)) 2205 return -EOPNOTSUPP; 2206 2207 /* 2208 * i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets 2209 * enabled. This is an efficient way of keeping the for-loop from 2210 * being executed when not needed. 2211 */ 2212 if (static_branch_unlikely(&i2c_trace_msg_key)) { 2213 int i; 2214 for (i = 0; i < num; i++) 2215 if (msgs[i].flags & I2C_M_RD) 2216 trace_i2c_read(adap, &msgs[i], i); 2217 else 2218 trace_i2c_write(adap, &msgs[i], i); 2219 } 2220 2221 /* Retry automatically on arbitration loss */ 2222 orig_jiffies = jiffies; 2223 for (ret = 0, try = 0; try <= adap->retries; try++) { 2224 if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic) 2225 ret = adap->algo->master_xfer_atomic(adap, msgs, num); 2226 else 2227 ret = adap->algo->master_xfer(adap, msgs, num); 2228 2229 if (ret != -EAGAIN) 2230 break; 2231 if (time_after(jiffies, orig_jiffies + adap->timeout)) 2232 break; 2233 } 2234 2235 if (static_branch_unlikely(&i2c_trace_msg_key)) { 2236 int i; 2237 for (i = 0; i < ret; i++) 2238 if (msgs[i].flags & I2C_M_RD) 2239 trace_i2c_reply(adap, &msgs[i], i); 2240 trace_i2c_result(adap, num, ret); 2241 } 2242 2243 return ret; 2244} 2245EXPORT_SYMBOL(__i2c_transfer); 2246 2247/** 2248 * i2c_transfer - execute a single or combined I2C message 2249 * @adap: Handle to I2C bus 2250 * @msgs: One or more messages to execute before STOP is issued to 2251 * terminate the operation; each message begins with a START. 2252 * @num: Number of messages to be executed. 2253 * 2254 * Returns negative errno, else the number of messages executed. 2255 * 2256 * Note that there is no requirement that each message be sent to 2257 * the same slave address, although that is the most common model. 2258 */ 2259int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 2260{ 2261 int ret; 2262 2263 if (!adap->algo->master_xfer) { 2264 dev_dbg(&adap->dev, "I2C level transfers not supported\n"); 2265 return -EOPNOTSUPP; 2266 } 2267 2268 /* REVISIT the fault reporting model here is weak: 2269 * 2270 * - When we get an error after receiving N bytes from a slave, 2271 * there is no way to report "N". 2272 * 2273 * - When we get a NAK after transmitting N bytes to a slave, 2274 * there is no way to report "N" ... or to let the master 2275 * continue executing the rest of this combined message, if 2276 * that's the appropriate response. 2277 * 2278 * - When for example "num" is two and we successfully complete 2279 * the first message but get an error part way through the 2280 * second, it's unclear whether that should be reported as 2281 * one (discarding status on the second message) or errno 2282 * (discarding status on the first one). 2283 */ 2284 ret = __i2c_lock_bus_helper(adap); 2285 if (ret) 2286 return ret; 2287 2288 ret = __i2c_transfer(adap, msgs, num); 2289 i2c_unlock_bus(adap, I2C_LOCK_SEGMENT); 2290 2291 return ret; 2292} 2293EXPORT_SYMBOL(i2c_transfer); 2294 2295/** 2296 * i2c_transfer_buffer_flags - issue a single I2C message transferring data 2297 * to/from a buffer 2298 * @client: Handle to slave device 2299 * @buf: Where the data is stored 2300 * @count: How many bytes to transfer, must be less than 64k since msg.len is u16 2301 * @flags: The flags to be used for the message, e.g. I2C_M_RD for reads 2302 * 2303 * Returns negative errno, or else the number of bytes transferred. 2304 */ 2305int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf, 2306 int count, u16 flags) 2307{ 2308 int ret; 2309 struct i2c_msg msg = { 2310 .addr = client->addr, 2311 .flags = flags | (client->flags & I2C_M_TEN), 2312 .len = count, 2313 .buf = buf, 2314 }; 2315 2316 ret = i2c_transfer(client->adapter, &msg, 1); 2317 2318 /* 2319 * If everything went ok (i.e. 1 msg transferred), return #bytes 2320 * transferred, else error code. 2321 */ 2322 return (ret == 1) ? count : ret; 2323} 2324EXPORT_SYMBOL(i2c_transfer_buffer_flags); 2325 2326/** 2327 * i2c_get_device_id - get manufacturer, part id and die revision of a device 2328 * @client: The device to query 2329 * @id: The queried information 2330 * 2331 * Returns negative errno on error, zero on success. 2332 */ 2333int i2c_get_device_id(const struct i2c_client *client, 2334 struct i2c_device_identity *id) 2335{ 2336 struct i2c_adapter *adap = client->adapter; 2337 union i2c_smbus_data raw_id; 2338 int ret; 2339 2340 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) 2341 return -EOPNOTSUPP; 2342 2343 raw_id.block[0] = 3; 2344 ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0, 2345 I2C_SMBUS_READ, client->addr << 1, 2346 I2C_SMBUS_I2C_BLOCK_DATA, &raw_id); 2347 if (ret) 2348 return ret; 2349 2350 id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4); 2351 id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3); 2352 id->die_revision = raw_id.block[3] & 0x7; 2353 return 0; 2354} 2355EXPORT_SYMBOL_GPL(i2c_get_device_id); 2356 2357/** 2358 * i2c_client_get_device_id - get the driver match table entry of a device 2359 * @client: the device to query. The device must be bound to a driver 2360 * 2361 * Returns a pointer to the matching entry if found, NULL otherwise. 2362 */ 2363const struct i2c_device_id *i2c_client_get_device_id(const struct i2c_client *client) 2364{ 2365 const struct i2c_driver *drv = to_i2c_driver(client->dev.driver); 2366 2367 return i2c_match_id(drv->id_table, client); 2368} 2369EXPORT_SYMBOL_GPL(i2c_client_get_device_id); 2370 2371/* ---------------------------------------------------- 2372 * the i2c address scanning function 2373 * Will not work for 10-bit addresses! 2374 * ---------------------------------------------------- 2375 */ 2376 2377/* 2378 * Legacy default probe function, mostly relevant for SMBus. The default 2379 * probe method is a quick write, but it is known to corrupt the 24RF08 2380 * EEPROMs due to a state machine bug, and could also irreversibly 2381 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f, 2382 * we use a short byte read instead. Also, some bus drivers don't implement 2383 * quick write, so we fallback to a byte read in that case too. 2384 * On x86, there is another special case for FSC hardware monitoring chips, 2385 * which want regular byte reads (address 0x73.) Fortunately, these are the 2386 * only known chips using this I2C address on PC hardware. 2387 * Returns 1 if probe succeeded, 0 if not. 2388 */ 2389static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr) 2390{ 2391 int err; 2392 union i2c_smbus_data dummy; 2393 2394#ifdef CONFIG_X86 2395 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON) 2396 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA)) 2397 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, 2398 I2C_SMBUS_BYTE_DATA, &dummy); 2399 else 2400#endif 2401 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50) 2402 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK)) 2403 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0, 2404 I2C_SMBUS_QUICK, NULL); 2405 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE)) 2406 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, 2407 I2C_SMBUS_BYTE, &dummy); 2408 else { 2409 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n", 2410 addr); 2411 err = -EOPNOTSUPP; 2412 } 2413 2414 return err >= 0; 2415} 2416 2417static int i2c_detect_address(struct i2c_client *temp_client, 2418 struct i2c_driver *driver) 2419{ 2420 struct i2c_board_info info; 2421 struct i2c_adapter *adapter = temp_client->adapter; 2422 int addr = temp_client->addr; 2423 int err; 2424 2425 /* Make sure the address is valid */ 2426 err = i2c_check_7bit_addr_validity_strict(addr); 2427 if (err) { 2428 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n", 2429 addr); 2430 return err; 2431 } 2432 2433 /* Skip if already in use (7 bit, no need to encode flags) */ 2434 if (i2c_check_addr_busy(adapter, addr)) 2435 return 0; 2436 2437 /* Make sure there is something at this address */ 2438 if (!i2c_default_probe(adapter, addr)) 2439 return 0; 2440 2441 /* Finally call the custom detection function */ 2442 memset(&info, 0, sizeof(struct i2c_board_info)); 2443 info.addr = addr; 2444 err = driver->detect(temp_client, &info); 2445 if (err) { 2446 /* -ENODEV is returned if the detection fails. We catch it 2447 here as this isn't an error. */ 2448 return err == -ENODEV ? 0 : err; 2449 } 2450 2451 /* Consistency check */ 2452 if (info.type[0] == '\0') { 2453 dev_err(&adapter->dev, 2454 "%s detection function provided no name for 0x%x\n", 2455 driver->driver.name, addr); 2456 } else { 2457 struct i2c_client *client; 2458 2459 /* Detection succeeded, instantiate the device */ 2460 if (adapter->class & I2C_CLASS_DEPRECATED) 2461 dev_warn(&adapter->dev, 2462 "This adapter will soon drop class based instantiation of devices. " 2463 "Please make sure client 0x%02x gets instantiated by other means. " 2464 "Check 'Documentation/i2c/instantiating-devices.rst' for details.\n", 2465 info.addr); 2466 2467 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n", 2468 info.type, info.addr); 2469 client = i2c_new_client_device(adapter, &info); 2470 if (!IS_ERR(client)) 2471 list_add_tail(&client->detected, &driver->clients); 2472 else 2473 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n", 2474 info.type, info.addr); 2475 } 2476 return 0; 2477} 2478 2479static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver) 2480{ 2481 const unsigned short *address_list; 2482 struct i2c_client *temp_client; 2483 int i, err = 0; 2484 2485 address_list = driver->address_list; 2486 if (!driver->detect || !address_list) 2487 return 0; 2488 2489 /* Warn that the adapter lost class based instantiation */ 2490 if (adapter->class == I2C_CLASS_DEPRECATED) { 2491 dev_dbg(&adapter->dev, 2492 "This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. " 2493 "If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n", 2494 driver->driver.name); 2495 return 0; 2496 } 2497 2498 /* Stop here if the classes do not match */ 2499 if (!(adapter->class & driver->class)) 2500 return 0; 2501 2502 /* Set up a temporary client to help detect callback */ 2503 temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL); 2504 if (!temp_client) 2505 return -ENOMEM; 2506 temp_client->adapter = adapter; 2507 2508 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) { 2509 dev_dbg(&adapter->dev, 2510 "found normal entry for adapter %d, addr 0x%02x\n", 2511 i2c_adapter_id(adapter), address_list[i]); 2512 temp_client->addr = address_list[i]; 2513 err = i2c_detect_address(temp_client, driver); 2514 if (unlikely(err)) 2515 break; 2516 } 2517 2518 kfree(temp_client); 2519 return err; 2520} 2521 2522int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr) 2523{ 2524 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, 2525 I2C_SMBUS_QUICK, NULL) >= 0; 2526} 2527EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read); 2528 2529struct i2c_client * 2530i2c_new_scanned_device(struct i2c_adapter *adap, 2531 struct i2c_board_info *info, 2532 unsigned short const *addr_list, 2533 int (*probe)(struct i2c_adapter *adap, unsigned short addr)) 2534{ 2535 int i; 2536 2537 if (!probe) 2538 probe = i2c_default_probe; 2539 2540 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) { 2541 /* Check address validity */ 2542 if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) { 2543 dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n", 2544 addr_list[i]); 2545 continue; 2546 } 2547 2548 /* Check address availability (7 bit, no need to encode flags) */ 2549 if (i2c_check_addr_busy(adap, addr_list[i])) { 2550 dev_dbg(&adap->dev, 2551 "Address 0x%02x already in use, not probing\n", 2552 addr_list[i]); 2553 continue; 2554 } 2555 2556 /* Test address responsiveness */ 2557 if (probe(adap, addr_list[i])) 2558 break; 2559 } 2560 2561 if (addr_list[i] == I2C_CLIENT_END) { 2562 dev_dbg(&adap->dev, "Probing failed, no device found\n"); 2563 return ERR_PTR(-ENODEV); 2564 } 2565 2566 info->addr = addr_list[i]; 2567 return i2c_new_client_device(adap, info); 2568} 2569EXPORT_SYMBOL_GPL(i2c_new_scanned_device); 2570 2571struct i2c_adapter *i2c_get_adapter(int nr) 2572{ 2573 struct i2c_adapter *adapter; 2574 2575 mutex_lock(&core_lock); 2576 adapter = idr_find(&i2c_adapter_idr, nr); 2577 if (!adapter) 2578 goto exit; 2579 2580 if (try_module_get(adapter->owner)) 2581 get_device(&adapter->dev); 2582 else 2583 adapter = NULL; 2584 2585 exit: 2586 mutex_unlock(&core_lock); 2587 return adapter; 2588} 2589EXPORT_SYMBOL(i2c_get_adapter); 2590 2591void i2c_put_adapter(struct i2c_adapter *adap) 2592{ 2593 if (!adap) 2594 return; 2595 2596 module_put(adap->owner); 2597 /* Should be last, otherwise we risk use-after-free with 'adap' */ 2598 put_device(&adap->dev); 2599} 2600EXPORT_SYMBOL(i2c_put_adapter); 2601 2602/** 2603 * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg 2604 * @msg: the message to be checked 2605 * @threshold: the minimum number of bytes for which using DMA makes sense. 2606 * Should at least be 1. 2607 * 2608 * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO. 2609 * Or a valid pointer to be used with DMA. After use, release it by 2610 * calling i2c_put_dma_safe_msg_buf(). 2611 * 2612 * This function must only be called from process context! 2613 */ 2614u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold) 2615{ 2616 /* also skip 0-length msgs for bogus thresholds of 0 */ 2617 if (!threshold) 2618 pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n", 2619 msg->addr); 2620 if (msg->len < threshold || msg->len == 0) 2621 return NULL; 2622 2623 if (msg->flags & I2C_M_DMA_SAFE) 2624 return msg->buf; 2625 2626 pr_debug("using bounce buffer for addr=0x%02x, len=%d\n", 2627 msg->addr, msg->len); 2628 2629 if (msg->flags & I2C_M_RD) 2630 return kzalloc(msg->len, GFP_KERNEL); 2631 else 2632 return kmemdup(msg->buf, msg->len, GFP_KERNEL); 2633} 2634EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf); 2635 2636/** 2637 * i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg 2638 * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL. 2639 * @msg: the message which the buffer corresponds to 2640 * @xferred: bool saying if the message was transferred 2641 */ 2642void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred) 2643{ 2644 if (!buf || buf == msg->buf) 2645 return; 2646 2647 if (xferred && msg->flags & I2C_M_RD) 2648 memcpy(msg->buf, buf, msg->len); 2649 2650 kfree(buf); 2651} 2652EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf); 2653 2654MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>"); 2655MODULE_DESCRIPTION("I2C-Bus main module"); 2656MODULE_LICENSE("GPL"); 2657