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/debugfs.h> 20 #include <linux/delay.h> 21 #include <linux/err.h> 22 #include <linux/errno.h> 23 #include <linux/gpio/consumer.h> 24 #include <linux/i2c.h> 25 #include <linux/i2c-smbus.h> 26 #include <linux/idr.h> 27 #include <linux/init.h> 28 #include <linux/interrupt.h> 29 #include <linux/irq.h> 30 #include <linux/jump_label.h> 31 #include <linux/kernel.h> 32 #include <linux/module.h> 33 #include <linux/mutex.h> 34 #include <linux/of_device.h> 35 #include <linux/of.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 #include <linux/string_choices.h> 45 46 #include "i2c-core.h" 47 48 #define CREATE_TRACE_POINTS 49 #include <trace/events/i2c.h> 50 51 #define I2C_ADDR_OFFSET_TEN_BIT 0xa000 52 #define I2C_ADDR_OFFSET_SLAVE 0x1000 53 54 #define I2C_ADDR_7BITS_MAX 0x77 55 #define I2C_ADDR_7BITS_COUNT (I2C_ADDR_7BITS_MAX + 1) 56 57 #define I2C_ADDR_DEVICE_ID 0x7c 58 59 /* 60 * core_lock protects i2c_adapter_idr, and guarantees that device detection, 61 * deletion of detected devices are serialized 62 */ 63 static DEFINE_MUTEX(core_lock); 64 static DEFINE_IDR(i2c_adapter_idr); 65 66 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver); 67 68 static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key); 69 static bool is_registered; 70 71 static struct dentry *i2c_debugfs_root; 72 73 int i2c_transfer_trace_reg(void) 74 { 75 static_branch_inc(&i2c_trace_msg_key); 76 return 0; 77 } 78 79 void i2c_transfer_trace_unreg(void) 80 { 81 static_branch_dec(&i2c_trace_msg_key); 82 } 83 84 const char *i2c_freq_mode_string(u32 bus_freq_hz) 85 { 86 switch (bus_freq_hz) { 87 case I2C_MAX_STANDARD_MODE_FREQ: 88 return "Standard Mode (100 kHz)"; 89 case I2C_MAX_FAST_MODE_FREQ: 90 return "Fast Mode (400 kHz)"; 91 case I2C_MAX_FAST_MODE_PLUS_FREQ: 92 return "Fast Mode Plus (1.0 MHz)"; 93 case I2C_MAX_TURBO_MODE_FREQ: 94 return "Turbo Mode (1.4 MHz)"; 95 case I2C_MAX_HIGH_SPEED_MODE_FREQ: 96 return "High Speed Mode (3.4 MHz)"; 97 case I2C_MAX_ULTRA_FAST_MODE_FREQ: 98 return "Ultra Fast Mode (5.0 MHz)"; 99 default: 100 return "Unknown Mode"; 101 } 102 } 103 EXPORT_SYMBOL_GPL(i2c_freq_mode_string); 104 105 const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id, 106 const struct i2c_client *client) 107 { 108 if (!(id && client)) 109 return NULL; 110 111 while (id->name[0]) { 112 if (strcmp(client->name, id->name) == 0) 113 return id; 114 id++; 115 } 116 return NULL; 117 } 118 EXPORT_SYMBOL_GPL(i2c_match_id); 119 120 const void *i2c_get_match_data(const struct i2c_client *client) 121 { 122 struct i2c_driver *driver = to_i2c_driver(client->dev.driver); 123 const struct i2c_device_id *match; 124 const void *data; 125 126 data = device_get_match_data(&client->dev); 127 if (!data) { 128 match = i2c_match_id(driver->id_table, client); 129 if (!match) 130 return NULL; 131 132 data = (const void *)match->driver_data; 133 } 134 135 return data; 136 } 137 EXPORT_SYMBOL(i2c_get_match_data); 138 139 static int i2c_device_match(struct device *dev, const struct device_driver *drv) 140 { 141 struct i2c_client *client = i2c_verify_client(dev); 142 const struct i2c_driver *driver; 143 144 145 /* Attempt an OF style match */ 146 if (i2c_of_match_device(drv->of_match_table, client)) 147 return 1; 148 149 /* Then ACPI style match */ 150 if (acpi_driver_match_device(dev, drv)) 151 return 1; 152 153 driver = to_i2c_driver(drv); 154 155 /* Finally an I2C match */ 156 if (i2c_match_id(driver->id_table, client)) 157 return 1; 158 159 return 0; 160 } 161 162 static int i2c_device_uevent(const struct device *dev, struct kobj_uevent_env *env) 163 { 164 const struct i2c_client *client = to_i2c_client(dev); 165 int rc; 166 167 rc = of_device_uevent_modalias(dev, env); 168 if (rc != -ENODEV) 169 return rc; 170 171 rc = acpi_device_uevent_modalias(dev, env); 172 if (rc != -ENODEV) 173 return rc; 174 175 return add_uevent_var(env, "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name); 176 } 177 178 /* i2c bus recovery routines */ 179 static int get_scl_gpio_value(struct i2c_adapter *adap) 180 { 181 return gpiod_get_value_cansleep(adap->bus_recovery_info->scl_gpiod); 182 } 183 184 static void set_scl_gpio_value(struct i2c_adapter *adap, int val) 185 { 186 gpiod_set_value_cansleep(adap->bus_recovery_info->scl_gpiod, val); 187 } 188 189 static int get_sda_gpio_value(struct i2c_adapter *adap) 190 { 191 return gpiod_get_value_cansleep(adap->bus_recovery_info->sda_gpiod); 192 } 193 194 static void set_sda_gpio_value(struct i2c_adapter *adap, int val) 195 { 196 gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val); 197 } 198 199 static int i2c_generic_bus_free(struct i2c_adapter *adap) 200 { 201 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 202 int ret = -EOPNOTSUPP; 203 204 if (bri->get_bus_free) 205 ret = bri->get_bus_free(adap); 206 else if (bri->get_sda) 207 ret = bri->get_sda(adap); 208 209 if (ret < 0) 210 return ret; 211 212 return ret ? 0 : -EBUSY; 213 } 214 215 /* 216 * We are generating clock pulses. ndelay() determines durating of clk pulses. 217 * We will generate clock with rate 100 KHz and so duration of both clock levels 218 * is: delay in ns = (10^6 / 100) / 2 219 */ 220 #define RECOVERY_NDELAY 5000 221 #define RECOVERY_CLK_CNT 9 222 223 int i2c_generic_scl_recovery(struct i2c_adapter *adap) 224 { 225 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 226 int i = 0, scl = 1, ret = 0; 227 228 if (bri->prepare_recovery) 229 bri->prepare_recovery(adap); 230 if (bri->pinctrl) 231 pinctrl_select_state(bri->pinctrl, bri->pins_gpio); 232 233 /* 234 * If we can set SDA, we will always create a STOP to ensure additional 235 * pulses will do no harm. This is achieved by letting SDA follow SCL 236 * half a cycle later. Check the 'incomplete_write_byte' fault injector 237 * for details. Note that we must honour tsu:sto, 4us, but lets use 5us 238 * here for simplicity. 239 */ 240 bri->set_scl(adap, scl); 241 ndelay(RECOVERY_NDELAY); 242 if (bri->set_sda) 243 bri->set_sda(adap, scl); 244 ndelay(RECOVERY_NDELAY / 2); 245 246 /* 247 * By this time SCL is high, as we need to give 9 falling-rising edges 248 */ 249 while (i++ < RECOVERY_CLK_CNT * 2) { 250 if (scl) { 251 /* SCL shouldn't be low here */ 252 if (!bri->get_scl(adap)) { 253 dev_err(&adap->dev, 254 "SCL is stuck low, exit recovery\n"); 255 ret = -EBUSY; 256 break; 257 } 258 } 259 260 scl = !scl; 261 bri->set_scl(adap, scl); 262 /* Creating STOP again, see above */ 263 if (scl) { 264 /* Honour minimum tsu:sto */ 265 ndelay(RECOVERY_NDELAY); 266 } else { 267 /* Honour minimum tf and thd:dat */ 268 ndelay(RECOVERY_NDELAY / 2); 269 } 270 if (bri->set_sda) 271 bri->set_sda(adap, scl); 272 ndelay(RECOVERY_NDELAY / 2); 273 274 if (scl) { 275 ret = i2c_generic_bus_free(adap); 276 if (ret == 0) 277 break; 278 } 279 } 280 281 /* If we can't check bus status, assume recovery worked */ 282 if (ret == -EOPNOTSUPP) 283 ret = 0; 284 285 if (bri->unprepare_recovery) 286 bri->unprepare_recovery(adap); 287 if (bri->pinctrl) 288 pinctrl_select_state(bri->pinctrl, bri->pins_default); 289 290 return ret; 291 } 292 EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery); 293 294 int i2c_recover_bus(struct i2c_adapter *adap) 295 { 296 if (!adap->bus_recovery_info) 297 return -EBUSY; 298 299 dev_dbg(&adap->dev, "Trying i2c bus recovery\n"); 300 return adap->bus_recovery_info->recover_bus(adap); 301 } 302 EXPORT_SYMBOL_GPL(i2c_recover_bus); 303 304 static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap) 305 { 306 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 307 struct device *dev = &adap->dev; 308 struct pinctrl *p = bri->pinctrl ?: dev_pinctrl(dev->parent); 309 310 bri->pinctrl = p; 311 312 /* 313 * we can't change states without pinctrl, so remove the states if 314 * populated 315 */ 316 if (!p) { 317 bri->pins_default = NULL; 318 bri->pins_gpio = NULL; 319 return; 320 } 321 322 if (!bri->pins_default) { 323 bri->pins_default = pinctrl_lookup_state(p, 324 PINCTRL_STATE_DEFAULT); 325 if (IS_ERR(bri->pins_default)) { 326 dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found for GPIO recovery\n"); 327 bri->pins_default = NULL; 328 } 329 } 330 if (!bri->pins_gpio) { 331 bri->pins_gpio = pinctrl_lookup_state(p, "gpio"); 332 if (IS_ERR(bri->pins_gpio)) 333 bri->pins_gpio = pinctrl_lookup_state(p, "recovery"); 334 335 if (IS_ERR(bri->pins_gpio)) { 336 dev_dbg(dev, "no gpio or recovery state found for GPIO recovery\n"); 337 bri->pins_gpio = NULL; 338 } 339 } 340 341 /* for pinctrl state changes, we need all the information */ 342 if (bri->pins_default && bri->pins_gpio) { 343 dev_info(dev, "using pinctrl states for GPIO recovery"); 344 } else { 345 bri->pinctrl = NULL; 346 bri->pins_default = NULL; 347 bri->pins_gpio = NULL; 348 } 349 } 350 351 static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap) 352 { 353 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 354 struct device *dev = &adap->dev; 355 struct gpio_desc *gpiod; 356 int ret = 0; 357 358 /* 359 * don't touch the recovery information if the driver is not using 360 * generic SCL recovery 361 */ 362 if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery) 363 return 0; 364 365 /* 366 * pins might be taken as GPIO, so we should inform pinctrl about 367 * this and move the state to GPIO 368 */ 369 if (bri->pinctrl) 370 pinctrl_select_state(bri->pinctrl, bri->pins_gpio); 371 372 /* 373 * if there is incomplete or no recovery information, see if generic 374 * GPIO recovery is available 375 */ 376 if (!bri->scl_gpiod) { 377 gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN); 378 if (PTR_ERR(gpiod) == -EPROBE_DEFER) { 379 ret = -EPROBE_DEFER; 380 goto cleanup_pinctrl_state; 381 } 382 if (!IS_ERR(gpiod)) { 383 bri->scl_gpiod = gpiod; 384 bri->recover_bus = i2c_generic_scl_recovery; 385 dev_info(dev, "using generic GPIOs for recovery\n"); 386 } 387 } 388 389 /* SDA GPIOD line is optional, so we care about DEFER only */ 390 if (!bri->sda_gpiod) { 391 /* 392 * We have SCL. Pull SCL low and wait a bit so that SDA glitches 393 * have no effect. 394 */ 395 gpiod_direction_output(bri->scl_gpiod, 0); 396 udelay(10); 397 gpiod = devm_gpiod_get(dev, "sda", GPIOD_IN); 398 399 /* Wait a bit in case of a SDA glitch, and then release SCL. */ 400 udelay(10); 401 gpiod_direction_output(bri->scl_gpiod, 1); 402 403 if (PTR_ERR(gpiod) == -EPROBE_DEFER) { 404 ret = -EPROBE_DEFER; 405 goto cleanup_pinctrl_state; 406 } 407 if (!IS_ERR(gpiod)) 408 bri->sda_gpiod = gpiod; 409 } 410 411 cleanup_pinctrl_state: 412 /* change the state of the pins back to their default state */ 413 if (bri->pinctrl) 414 pinctrl_select_state(bri->pinctrl, bri->pins_default); 415 416 return ret; 417 } 418 419 static int i2c_gpio_init_recovery(struct i2c_adapter *adap) 420 { 421 i2c_gpio_init_pinctrl_recovery(adap); 422 return i2c_gpio_init_generic_recovery(adap); 423 } 424 425 static int i2c_init_recovery(struct i2c_adapter *adap) 426 { 427 struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; 428 bool is_error_level = true; 429 char *err_str; 430 431 if (!bri) 432 return 0; 433 434 if (i2c_gpio_init_recovery(adap) == -EPROBE_DEFER) 435 return -EPROBE_DEFER; 436 437 if (!bri->recover_bus) { 438 err_str = "no suitable method provided"; 439 is_error_level = false; 440 goto err; 441 } 442 443 if (bri->scl_gpiod && bri->recover_bus == i2c_generic_scl_recovery) { 444 bri->get_scl = get_scl_gpio_value; 445 bri->set_scl = set_scl_gpio_value; 446 if (bri->sda_gpiod) { 447 bri->get_sda = get_sda_gpio_value; 448 /* FIXME: add proper flag instead of '0' once available */ 449 if (gpiod_get_direction(bri->sda_gpiod) == 0) 450 bri->set_sda = set_sda_gpio_value; 451 } 452 } else if (bri->recover_bus == i2c_generic_scl_recovery) { 453 /* Generic SCL recovery */ 454 if (!bri->set_scl || !bri->get_scl) { 455 err_str = "no {get|set}_scl() found"; 456 goto err; 457 } 458 if (!bri->set_sda && !bri->get_sda) { 459 err_str = "either get_sda() or set_sda() needed"; 460 goto err; 461 } 462 } 463 464 return 0; 465 err: 466 if (is_error_level) 467 dev_err(&adap->dev, "Not using recovery: %s\n", err_str); 468 else 469 dev_dbg(&adap->dev, "Not using recovery: %s\n", err_str); 470 adap->bus_recovery_info = NULL; 471 472 return -EINVAL; 473 } 474 475 static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client) 476 { 477 struct i2c_adapter *adap = client->adapter; 478 unsigned int irq; 479 480 if (!adap->host_notify_domain) 481 return -ENXIO; 482 483 if (client->flags & I2C_CLIENT_TEN) 484 return -EINVAL; 485 486 irq = irq_create_mapping(adap->host_notify_domain, client->addr); 487 488 return irq > 0 ? irq : -ENXIO; 489 } 490 491 static int i2c_device_probe(struct device *dev) 492 { 493 struct fwnode_handle *fwnode = dev_fwnode(dev); 494 struct i2c_client *client = i2c_verify_client(dev); 495 struct i2c_driver *driver; 496 bool do_power_on; 497 int status; 498 499 if (!client) 500 return 0; 501 502 client->irq = client->init_irq; 503 504 if (!client->irq) { 505 int irq = -ENOENT; 506 507 if (client->flags & I2C_CLIENT_HOST_NOTIFY) { 508 dev_dbg(dev, "Using Host Notify IRQ\n"); 509 /* Keep adapter active when Host Notify is required */ 510 pm_runtime_get_sync(&client->adapter->dev); 511 irq = i2c_smbus_host_notify_to_irq(client); 512 } else if (is_of_node(fwnode)) { 513 irq = fwnode_irq_get_byname(fwnode, "irq"); 514 if (irq == -EINVAL || irq == -ENODATA) 515 irq = fwnode_irq_get(fwnode, 0); 516 } else if (is_acpi_device_node(fwnode)) { 517 bool wake_capable; 518 519 irq = i2c_acpi_get_irq(client, &wake_capable); 520 if (irq > 0 && wake_capable) 521 client->flags |= I2C_CLIENT_WAKE; 522 } 523 if (irq == -EPROBE_DEFER) { 524 status = dev_err_probe(dev, irq, "can't get irq\n"); 525 goto put_sync_adapter; 526 } 527 528 if (irq < 0) 529 irq = 0; 530 531 client->irq = irq; 532 } 533 534 driver = to_i2c_driver(dev->driver); 535 536 /* 537 * An I2C ID table is not mandatory, if and only if, a suitable OF 538 * or ACPI ID table is supplied for the probing device. 539 */ 540 if (!driver->id_table && 541 !acpi_driver_match_device(dev, dev->driver) && 542 !i2c_of_match_device(dev->driver->of_match_table, client)) { 543 status = -ENODEV; 544 goto put_sync_adapter; 545 } 546 547 if (client->flags & I2C_CLIENT_WAKE) { 548 int wakeirq; 549 550 wakeirq = fwnode_irq_get_byname(fwnode, "wakeup"); 551 if (wakeirq == -EPROBE_DEFER) { 552 status = dev_err_probe(dev, wakeirq, "can't get wakeirq\n"); 553 goto put_sync_adapter; 554 } 555 556 device_init_wakeup(&client->dev, true); 557 558 if (wakeirq > 0 && wakeirq != client->irq) 559 status = dev_pm_set_dedicated_wake_irq(dev, wakeirq); 560 else if (client->irq > 0) 561 status = dev_pm_set_wake_irq(dev, client->irq); 562 else 563 status = 0; 564 565 if (status) 566 dev_warn(&client->dev, "failed to set up wakeup irq\n"); 567 } 568 569 dev_dbg(dev, "probe\n"); 570 571 status = of_clk_set_defaults(to_of_node(fwnode), false); 572 if (status < 0) 573 goto err_clear_wakeup_irq; 574 575 do_power_on = !i2c_acpi_waive_d0_probe(dev); 576 status = dev_pm_domain_attach(&client->dev, do_power_on); 577 if (status) 578 goto err_clear_wakeup_irq; 579 580 client->devres_group_id = devres_open_group(&client->dev, NULL, 581 GFP_KERNEL); 582 if (!client->devres_group_id) { 583 status = -ENOMEM; 584 goto err_detach_pm_domain; 585 } 586 587 client->debugfs = debugfs_create_dir(dev_name(&client->dev), 588 client->adapter->debugfs); 589 590 if (driver->probe) 591 status = driver->probe(client); 592 else 593 status = -EINVAL; 594 595 /* 596 * Note that we are not closing the devres group opened above so 597 * even resources that were attached to the device after probe is 598 * run are released when i2c_device_remove() is executed. This is 599 * needed as some drivers would allocate additional resources, 600 * for example when updating firmware. 601 */ 602 603 if (status) 604 goto err_release_driver_resources; 605 606 return 0; 607 608 err_release_driver_resources: 609 debugfs_remove_recursive(client->debugfs); 610 devres_release_group(&client->dev, client->devres_group_id); 611 err_detach_pm_domain: 612 dev_pm_domain_detach(&client->dev, do_power_on); 613 err_clear_wakeup_irq: 614 dev_pm_clear_wake_irq(&client->dev); 615 device_init_wakeup(&client->dev, false); 616 put_sync_adapter: 617 if (client->flags & I2C_CLIENT_HOST_NOTIFY) 618 pm_runtime_put_sync(&client->adapter->dev); 619 620 return status; 621 } 622 623 static void i2c_device_remove(struct device *dev) 624 { 625 struct i2c_client *client = to_i2c_client(dev); 626 struct i2c_driver *driver; 627 628 driver = to_i2c_driver(dev->driver); 629 if (driver->remove) { 630 dev_dbg(dev, "remove\n"); 631 632 driver->remove(client); 633 } 634 635 debugfs_remove_recursive(client->debugfs); 636 637 devres_release_group(&client->dev, client->devres_group_id); 638 639 dev_pm_domain_detach(&client->dev, true); 640 641 dev_pm_clear_wake_irq(&client->dev); 642 device_init_wakeup(&client->dev, false); 643 644 client->irq = 0; 645 if (client->flags & I2C_CLIENT_HOST_NOTIFY) 646 pm_runtime_put(&client->adapter->dev); 647 } 648 649 static void i2c_device_shutdown(struct device *dev) 650 { 651 struct i2c_client *client = i2c_verify_client(dev); 652 struct i2c_driver *driver; 653 654 if (!client || !dev->driver) 655 return; 656 driver = to_i2c_driver(dev->driver); 657 if (driver->shutdown) 658 driver->shutdown(client); 659 else if (client->irq > 0) 660 disable_irq(client->irq); 661 } 662 663 static void i2c_client_dev_release(struct device *dev) 664 { 665 kfree(to_i2c_client(dev)); 666 } 667 668 static ssize_t 669 name_show(struct device *dev, struct device_attribute *attr, char *buf) 670 { 671 return sprintf(buf, "%s\n", dev->type == &i2c_client_type ? 672 to_i2c_client(dev)->name : to_i2c_adapter(dev)->name); 673 } 674 static DEVICE_ATTR_RO(name); 675 676 static ssize_t 677 modalias_show(struct device *dev, struct device_attribute *attr, char *buf) 678 { 679 struct i2c_client *client = to_i2c_client(dev); 680 int len; 681 682 len = of_device_modalias(dev, buf, PAGE_SIZE); 683 if (len != -ENODEV) 684 return len; 685 686 len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1); 687 if (len != -ENODEV) 688 return len; 689 690 return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name); 691 } 692 static DEVICE_ATTR_RO(modalias); 693 694 static struct attribute *i2c_dev_attrs[] = { 695 &dev_attr_name.attr, 696 /* modalias helps coldplug: modprobe $(cat .../modalias) */ 697 &dev_attr_modalias.attr, 698 NULL 699 }; 700 ATTRIBUTE_GROUPS(i2c_dev); 701 702 const struct bus_type i2c_bus_type = { 703 .name = "i2c", 704 .match = i2c_device_match, 705 .probe = i2c_device_probe, 706 .remove = i2c_device_remove, 707 .shutdown = i2c_device_shutdown, 708 }; 709 EXPORT_SYMBOL_GPL(i2c_bus_type); 710 711 const struct device_type i2c_client_type = { 712 .groups = i2c_dev_groups, 713 .uevent = i2c_device_uevent, 714 .release = i2c_client_dev_release, 715 }; 716 EXPORT_SYMBOL_GPL(i2c_client_type); 717 718 719 /** 720 * i2c_verify_client - return parameter as i2c_client, or NULL 721 * @dev: device, probably from some driver model iterator 722 * 723 * When traversing the driver model tree, perhaps using driver model 724 * iterators like @device_for_each_child(), you can't assume very much 725 * about the nodes you find. Use this function to avoid oopses caused 726 * by wrongly treating some non-I2C device as an i2c_client. 727 */ 728 struct i2c_client *i2c_verify_client(struct device *dev) 729 { 730 return (dev->type == &i2c_client_type) 731 ? to_i2c_client(dev) 732 : NULL; 733 } 734 EXPORT_SYMBOL(i2c_verify_client); 735 736 737 /* Return a unique address which takes the flags of the client into account */ 738 static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client) 739 { 740 unsigned short addr = client->addr; 741 742 /* For some client flags, add an arbitrary offset to avoid collisions */ 743 if (client->flags & I2C_CLIENT_TEN) 744 addr |= I2C_ADDR_OFFSET_TEN_BIT; 745 746 if (client->flags & I2C_CLIENT_SLAVE) 747 addr |= I2C_ADDR_OFFSET_SLAVE; 748 749 return addr; 750 } 751 752 /* This is a permissive address validity check, I2C address map constraints 753 * are purposely not enforced, except for the general call address. */ 754 static int i2c_check_addr_validity(unsigned int addr, unsigned short flags) 755 { 756 if (flags & I2C_CLIENT_TEN) { 757 /* 10-bit address, all values are valid */ 758 if (addr > 0x3ff) 759 return -EINVAL; 760 } else { 761 /* 7-bit address, reject the general call address */ 762 if (addr == 0x00 || addr > 0x7f) 763 return -EINVAL; 764 } 765 return 0; 766 } 767 768 /* And this is a strict address validity check, used when probing. If a 769 * device uses a reserved address, then it shouldn't be probed. 7-bit 770 * addressing is assumed, 10-bit address devices are rare and should be 771 * explicitly enumerated. */ 772 int i2c_check_7bit_addr_validity_strict(unsigned short addr) 773 { 774 /* 775 * Reserved addresses per I2C specification: 776 * 0x00 General call address / START byte 777 * 0x01 CBUS address 778 * 0x02 Reserved for different bus format 779 * 0x03 Reserved for future purposes 780 * 0x04-0x07 Hs-mode master code 781 * 0x78-0x7b 10-bit slave addressing 782 * 0x7c-0x7f Reserved for future purposes 783 */ 784 if (addr < 0x08 || addr > 0x77) 785 return -EINVAL; 786 return 0; 787 } 788 789 static int __i2c_check_addr_busy(struct device *dev, void *addrp) 790 { 791 struct i2c_client *client = i2c_verify_client(dev); 792 int addr = *(int *)addrp; 793 794 if (client && i2c_encode_flags_to_addr(client) == addr) 795 return -EBUSY; 796 return 0; 797 } 798 799 /* walk up mux tree */ 800 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr) 801 { 802 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); 803 int result; 804 805 result = device_for_each_child(&adapter->dev, &addr, 806 __i2c_check_addr_busy); 807 808 if (!result && parent) 809 result = i2c_check_mux_parents(parent, addr); 810 811 return result; 812 } 813 814 /* recurse down mux tree */ 815 static int i2c_check_mux_children(struct device *dev, void *addrp) 816 { 817 int result; 818 819 if (dev->type == &i2c_adapter_type) 820 result = device_for_each_child(dev, addrp, 821 i2c_check_mux_children); 822 else 823 result = __i2c_check_addr_busy(dev, addrp); 824 825 return result; 826 } 827 828 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr) 829 { 830 struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter); 831 int result = 0; 832 833 if (parent) 834 result = i2c_check_mux_parents(parent, addr); 835 836 if (!result) 837 result = device_for_each_child(&adapter->dev, &addr, 838 i2c_check_mux_children); 839 840 return result; 841 } 842 843 /** 844 * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment 845 * @adapter: Target I2C bus segment 846 * @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT 847 * locks only this branch in the adapter tree 848 */ 849 static void i2c_adapter_lock_bus(struct i2c_adapter *adapter, 850 unsigned int flags) 851 { 852 rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter)); 853 } 854 855 /** 856 * i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment 857 * @adapter: Target I2C bus segment 858 * @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT 859 * trylocks only this branch in the adapter tree 860 */ 861 static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter, 862 unsigned int flags) 863 { 864 return rt_mutex_trylock(&adapter->bus_lock); 865 } 866 867 /** 868 * i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment 869 * @adapter: Target I2C bus segment 870 * @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT 871 * unlocks only this branch in the adapter tree 872 */ 873 static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter, 874 unsigned int flags) 875 { 876 rt_mutex_unlock(&adapter->bus_lock); 877 } 878 879 static void i2c_dev_set_name(struct i2c_adapter *adap, 880 struct i2c_client *client, 881 struct i2c_board_info const *info) 882 { 883 struct acpi_device *adev = ACPI_COMPANION(&client->dev); 884 885 if (info && info->dev_name) { 886 dev_set_name(&client->dev, "i2c-%s", info->dev_name); 887 return; 888 } 889 890 if (adev) { 891 dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev)); 892 return; 893 } 894 895 dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap), 896 i2c_encode_flags_to_addr(client)); 897 } 898 899 int i2c_dev_irq_from_resources(const struct resource *resources, 900 unsigned int num_resources) 901 { 902 struct irq_data *irqd; 903 int i; 904 905 for (i = 0; i < num_resources; i++) { 906 const struct resource *r = &resources[i]; 907 908 if (resource_type(r) != IORESOURCE_IRQ) 909 continue; 910 911 if (r->flags & IORESOURCE_BITS) { 912 irqd = irq_get_irq_data(r->start); 913 if (!irqd) 914 break; 915 916 irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS); 917 } 918 919 return r->start; 920 } 921 922 return 0; 923 } 924 925 /* 926 * Serialize device instantiation in case it can be instantiated explicitly 927 * and by auto-detection 928 */ 929 static int i2c_lock_addr(struct i2c_adapter *adap, unsigned short addr, 930 unsigned short flags) 931 { 932 if (!(flags & I2C_CLIENT_TEN) && 933 test_and_set_bit(addr, adap->addrs_in_instantiation)) 934 return -EBUSY; 935 936 return 0; 937 } 938 939 static void i2c_unlock_addr(struct i2c_adapter *adap, unsigned short addr, 940 unsigned short flags) 941 { 942 if (!(flags & I2C_CLIENT_TEN)) 943 clear_bit(addr, adap->addrs_in_instantiation); 944 } 945 946 /** 947 * i2c_new_client_device - instantiate an i2c device 948 * @adap: the adapter managing the device 949 * @info: describes one I2C device; bus_num is ignored 950 * Context: can sleep 951 * 952 * Create an i2c device. Binding is handled through driver model 953 * probe()/remove() methods. A driver may be bound to this device when we 954 * return from this function, or any later moment (e.g. maybe hotplugging will 955 * load the driver module). This call is not appropriate for use by mainboard 956 * initialization logic, which usually runs during an arch_initcall() long 957 * before any i2c_adapter could exist. 958 * 959 * This returns the new i2c client, which may be saved for later use with 960 * i2c_unregister_device(); or an ERR_PTR to describe the error. 961 */ 962 struct i2c_client * 963 i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info) 964 { 965 struct fwnode_handle *fwnode = info->fwnode; 966 struct i2c_client *client; 967 bool need_put = false; 968 int status; 969 970 client = kzalloc(sizeof *client, GFP_KERNEL); 971 if (!client) 972 return ERR_PTR(-ENOMEM); 973 974 client->adapter = adap; 975 976 client->dev.platform_data = info->platform_data; 977 client->flags = info->flags; 978 client->addr = info->addr; 979 980 client->init_irq = info->irq; 981 if (!client->init_irq) 982 client->init_irq = i2c_dev_irq_from_resources(info->resources, 983 info->num_resources); 984 985 strscpy(client->name, info->type, sizeof(client->name)); 986 987 status = i2c_check_addr_validity(client->addr, client->flags); 988 if (status) { 989 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n", 990 client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr); 991 goto out_err_silent; 992 } 993 994 status = i2c_lock_addr(adap, client->addr, client->flags); 995 if (status) 996 goto out_err_silent; 997 998 /* Check for address business */ 999 status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client)); 1000 if (status) 1001 goto out_err; 1002 1003 client->dev.parent = &client->adapter->dev; 1004 client->dev.bus = &i2c_bus_type; 1005 client->dev.type = &i2c_client_type; 1006 1007 device_enable_async_suspend(&client->dev); 1008 1009 device_set_node(&client->dev, fwnode_handle_get(fwnode)); 1010 1011 if (info->swnode) { 1012 status = device_add_software_node(&client->dev, info->swnode); 1013 if (status) { 1014 dev_err(&adap->dev, 1015 "Failed to add software node to client %s: %d\n", 1016 client->name, status); 1017 goto out_err_put_fwnode; 1018 } 1019 } 1020 1021 i2c_dev_set_name(adap, client, info); 1022 status = device_register(&client->dev); 1023 if (status) 1024 goto out_remove_swnode; 1025 1026 dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n", 1027 client->name, dev_name(&client->dev)); 1028 1029 i2c_unlock_addr(adap, client->addr, client->flags); 1030 1031 return client; 1032 1033 out_remove_swnode: 1034 device_remove_software_node(&client->dev); 1035 need_put = true; 1036 out_err_put_fwnode: 1037 fwnode_handle_put(fwnode); 1038 out_err: 1039 dev_err(&adap->dev, 1040 "Failed to register i2c client %s at 0x%02x (%d)\n", 1041 client->name, client->addr, status); 1042 i2c_unlock_addr(adap, client->addr, client->flags); 1043 out_err_silent: 1044 if (need_put) 1045 put_device(&client->dev); 1046 else 1047 kfree(client); 1048 return ERR_PTR(status); 1049 } 1050 EXPORT_SYMBOL_GPL(i2c_new_client_device); 1051 1052 /** 1053 * i2c_unregister_device - reverse effect of i2c_new_*_device() 1054 * @client: value returned from i2c_new_*_device() 1055 * Context: can sleep 1056 */ 1057 void i2c_unregister_device(struct i2c_client *client) 1058 { 1059 struct fwnode_handle *fwnode; 1060 1061 if (IS_ERR_OR_NULL(client)) 1062 return; 1063 1064 fwnode = dev_fwnode(&client->dev); 1065 if (is_of_node(fwnode)) 1066 of_node_clear_flag(to_of_node(fwnode), OF_POPULATED); 1067 else if (is_acpi_device_node(fwnode)) 1068 acpi_device_clear_enumerated(to_acpi_device_node(fwnode)); 1069 fwnode_handle_put(fwnode); 1070 1071 device_remove_software_node(&client->dev); 1072 device_unregister(&client->dev); 1073 } 1074 EXPORT_SYMBOL_GPL(i2c_unregister_device); 1075 1076 /** 1077 * i2c_find_device_by_fwnode() - find an i2c_client for the fwnode 1078 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_client 1079 * 1080 * Look up and return the &struct i2c_client corresponding to the @fwnode. 1081 * If no client can be found, or @fwnode is NULL, this returns NULL. 1082 * 1083 * The user must call put_device(&client->dev) once done with the i2c client. 1084 */ 1085 struct i2c_client *i2c_find_device_by_fwnode(struct fwnode_handle *fwnode) 1086 { 1087 struct i2c_client *client; 1088 struct device *dev; 1089 1090 if (!fwnode) 1091 return NULL; 1092 1093 dev = bus_find_device_by_fwnode(&i2c_bus_type, fwnode); 1094 if (!dev) 1095 return NULL; 1096 1097 client = i2c_verify_client(dev); 1098 if (!client) 1099 put_device(dev); 1100 1101 return client; 1102 } 1103 EXPORT_SYMBOL(i2c_find_device_by_fwnode); 1104 1105 1106 static const struct i2c_device_id dummy_id[] = { 1107 { "dummy", }, 1108 { "smbus_host_notify", }, 1109 { } 1110 }; 1111 1112 static int dummy_probe(struct i2c_client *client) 1113 { 1114 return 0; 1115 } 1116 1117 static struct i2c_driver dummy_driver = { 1118 .driver.name = "dummy", 1119 .probe = dummy_probe, 1120 .id_table = dummy_id, 1121 }; 1122 1123 /** 1124 * i2c_new_dummy_device - return a new i2c device bound to a dummy driver 1125 * @adapter: the adapter managing the device 1126 * @address: seven bit address to be used 1127 * Context: can sleep 1128 * 1129 * This returns an I2C client bound to the "dummy" driver, intended for use 1130 * with devices that consume multiple addresses. Examples of such chips 1131 * include various EEPROMS (like 24c04 and 24c08 models). 1132 * 1133 * These dummy devices have two main uses. First, most I2C and SMBus calls 1134 * except i2c_transfer() need a client handle; the dummy will be that handle. 1135 * And second, this prevents the specified address from being bound to a 1136 * different driver. 1137 * 1138 * This returns the new i2c client, which should be saved for later use with 1139 * i2c_unregister_device(); or an ERR_PTR to describe the error. 1140 */ 1141 struct i2c_client *i2c_new_dummy_device(struct i2c_adapter *adapter, u16 address) 1142 { 1143 struct i2c_board_info info = { 1144 I2C_BOARD_INFO("dummy", address), 1145 }; 1146 1147 return i2c_new_client_device(adapter, &info); 1148 } 1149 EXPORT_SYMBOL_GPL(i2c_new_dummy_device); 1150 1151 static void devm_i2c_release_dummy(void *client) 1152 { 1153 i2c_unregister_device(client); 1154 } 1155 1156 /** 1157 * devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver 1158 * @dev: device the managed resource is bound to 1159 * @adapter: the adapter managing the device 1160 * @address: seven bit address to be used 1161 * Context: can sleep 1162 * 1163 * This is the device-managed version of @i2c_new_dummy_device. It returns the 1164 * new i2c client or an ERR_PTR in case of an error. 1165 */ 1166 struct i2c_client *devm_i2c_new_dummy_device(struct device *dev, 1167 struct i2c_adapter *adapter, 1168 u16 address) 1169 { 1170 struct i2c_client *client; 1171 int ret; 1172 1173 client = i2c_new_dummy_device(adapter, address); 1174 if (IS_ERR(client)) 1175 return client; 1176 1177 ret = devm_add_action_or_reset(dev, devm_i2c_release_dummy, client); 1178 if (ret) 1179 return ERR_PTR(ret); 1180 1181 return client; 1182 } 1183 EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device); 1184 1185 /** 1186 * i2c_new_ancillary_device - Helper to get the instantiated secondary address 1187 * and create the associated device 1188 * @client: Handle to the primary client 1189 * @name: Handle to specify which secondary address to get 1190 * @default_addr: Used as a fallback if no secondary address was specified 1191 * Context: can sleep 1192 * 1193 * I2C clients can be composed of multiple I2C slaves bound together in a single 1194 * component. The I2C client driver then binds to the master I2C slave and needs 1195 * to create I2C dummy clients to communicate with all the other slaves. 1196 * 1197 * This function creates and returns an I2C dummy client whose I2C address is 1198 * retrieved from the platform firmware based on the given slave name. If no 1199 * address is specified by the firmware default_addr is used. 1200 * 1201 * On DT-based platforms the address is retrieved from the "reg" property entry 1202 * cell whose "reg-names" value matches the slave name. 1203 * 1204 * This returns the new i2c client, which should be saved for later use with 1205 * i2c_unregister_device(); or an ERR_PTR to describe the error. 1206 */ 1207 struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client, 1208 const char *name, 1209 u16 default_addr) 1210 { 1211 struct device_node *np = client->dev.of_node; 1212 u32 addr = default_addr; 1213 int i; 1214 1215 i = of_property_match_string(np, "reg-names", name); 1216 if (i >= 0) 1217 of_property_read_u32_index(np, "reg", i, &addr); 1218 1219 dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr); 1220 return i2c_new_dummy_device(client->adapter, addr); 1221 } 1222 EXPORT_SYMBOL_GPL(i2c_new_ancillary_device); 1223 1224 /* ------------------------------------------------------------------------- */ 1225 1226 /* I2C bus adapters -- one roots each I2C or SMBUS segment */ 1227 1228 static void i2c_adapter_dev_release(struct device *dev) 1229 { 1230 struct i2c_adapter *adap = to_i2c_adapter(dev); 1231 complete(&adap->dev_released); 1232 } 1233 1234 unsigned int i2c_adapter_depth(struct i2c_adapter *adapter) 1235 { 1236 unsigned int depth = 0; 1237 struct device *parent; 1238 1239 for (parent = adapter->dev.parent; parent; parent = parent->parent) 1240 if (parent->type == &i2c_adapter_type) 1241 depth++; 1242 1243 WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES, 1244 "adapter depth exceeds lockdep subclass limit\n"); 1245 1246 return depth; 1247 } 1248 EXPORT_SYMBOL_GPL(i2c_adapter_depth); 1249 1250 /* 1251 * Let users instantiate I2C devices through sysfs. This can be used when 1252 * platform initialization code doesn't contain the proper data for 1253 * whatever reason. Also useful for drivers that do device detection and 1254 * detection fails, either because the device uses an unexpected address, 1255 * or this is a compatible device with different ID register values. 1256 * 1257 * Parameter checking may look overzealous, but we really don't want 1258 * the user to provide incorrect parameters. 1259 */ 1260 static ssize_t 1261 new_device_store(struct device *dev, struct device_attribute *attr, 1262 const char *buf, size_t count) 1263 { 1264 struct i2c_adapter *adap = to_i2c_adapter(dev); 1265 struct i2c_board_info info; 1266 struct i2c_client *client; 1267 char *blank, end; 1268 int res; 1269 1270 memset(&info, 0, sizeof(struct i2c_board_info)); 1271 1272 blank = strchr(buf, ' '); 1273 if (!blank) { 1274 dev_err(dev, "%s: Missing parameters\n", "new_device"); 1275 return -EINVAL; 1276 } 1277 if (blank - buf > I2C_NAME_SIZE - 1) { 1278 dev_err(dev, "%s: Invalid device name\n", "new_device"); 1279 return -EINVAL; 1280 } 1281 memcpy(info.type, buf, blank - buf); 1282 1283 /* Parse remaining parameters, reject extra parameters */ 1284 res = sscanf(++blank, "%hi%c", &info.addr, &end); 1285 if (res < 1) { 1286 dev_err(dev, "%s: Can't parse I2C address\n", "new_device"); 1287 return -EINVAL; 1288 } 1289 if (res > 1 && end != '\n') { 1290 dev_err(dev, "%s: Extra parameters\n", "new_device"); 1291 return -EINVAL; 1292 } 1293 1294 if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) { 1295 info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT; 1296 info.flags |= I2C_CLIENT_TEN; 1297 } 1298 1299 if (info.addr & I2C_ADDR_OFFSET_SLAVE) { 1300 info.addr &= ~I2C_ADDR_OFFSET_SLAVE; 1301 info.flags |= I2C_CLIENT_SLAVE; 1302 } 1303 1304 client = i2c_new_client_device(adap, &info); 1305 if (IS_ERR(client)) 1306 return PTR_ERR(client); 1307 1308 /* Keep track of the added device */ 1309 mutex_lock(&adap->userspace_clients_lock); 1310 list_add_tail(&client->detected, &adap->userspace_clients); 1311 mutex_unlock(&adap->userspace_clients_lock); 1312 dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device", 1313 info.type, info.addr); 1314 1315 return count; 1316 } 1317 static DEVICE_ATTR_WO(new_device); 1318 1319 /* 1320 * And of course let the users delete the devices they instantiated, if 1321 * they got it wrong. This interface can only be used to delete devices 1322 * instantiated by i2c_sysfs_new_device above. This guarantees that we 1323 * don't delete devices to which some kernel code still has references. 1324 * 1325 * Parameter checking may look overzealous, but we really don't want 1326 * the user to delete the wrong device. 1327 */ 1328 static ssize_t 1329 delete_device_store(struct device *dev, struct device_attribute *attr, 1330 const char *buf, size_t count) 1331 { 1332 struct i2c_adapter *adap = to_i2c_adapter(dev); 1333 struct i2c_client *client, *next; 1334 unsigned short addr; 1335 char end; 1336 int res; 1337 1338 /* Parse parameters, reject extra parameters */ 1339 res = sscanf(buf, "%hi%c", &addr, &end); 1340 if (res < 1) { 1341 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device"); 1342 return -EINVAL; 1343 } 1344 if (res > 1 && end != '\n') { 1345 dev_err(dev, "%s: Extra parameters\n", "delete_device"); 1346 return -EINVAL; 1347 } 1348 1349 /* Make sure the device was added through sysfs */ 1350 res = -ENOENT; 1351 mutex_lock_nested(&adap->userspace_clients_lock, 1352 i2c_adapter_depth(adap)); 1353 list_for_each_entry_safe(client, next, &adap->userspace_clients, 1354 detected) { 1355 if (i2c_encode_flags_to_addr(client) == addr) { 1356 dev_info(dev, "%s: Deleting device %s at 0x%02hx\n", 1357 "delete_device", client->name, client->addr); 1358 1359 list_del(&client->detected); 1360 i2c_unregister_device(client); 1361 res = count; 1362 break; 1363 } 1364 } 1365 mutex_unlock(&adap->userspace_clients_lock); 1366 1367 if (res < 0) 1368 dev_err(dev, "%s: Can't find device in list\n", 1369 "delete_device"); 1370 return res; 1371 } 1372 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL, 1373 delete_device_store); 1374 1375 static struct attribute *i2c_adapter_attrs[] = { 1376 &dev_attr_name.attr, 1377 &dev_attr_new_device.attr, 1378 &dev_attr_delete_device.attr, 1379 NULL 1380 }; 1381 ATTRIBUTE_GROUPS(i2c_adapter); 1382 1383 const struct device_type i2c_adapter_type = { 1384 .groups = i2c_adapter_groups, 1385 .release = i2c_adapter_dev_release, 1386 }; 1387 EXPORT_SYMBOL_GPL(i2c_adapter_type); 1388 1389 /** 1390 * i2c_verify_adapter - return parameter as i2c_adapter or NULL 1391 * @dev: device, probably from some driver model iterator 1392 * 1393 * When traversing the driver model tree, perhaps using driver model 1394 * iterators like @device_for_each_child(), you can't assume very much 1395 * about the nodes you find. Use this function to avoid oopses caused 1396 * by wrongly treating some non-I2C device as an i2c_adapter. 1397 */ 1398 struct i2c_adapter *i2c_verify_adapter(struct device *dev) 1399 { 1400 return (dev->type == &i2c_adapter_type) 1401 ? to_i2c_adapter(dev) 1402 : NULL; 1403 } 1404 EXPORT_SYMBOL(i2c_verify_adapter); 1405 1406 static void i2c_scan_static_board_info(struct i2c_adapter *adapter) 1407 { 1408 struct i2c_devinfo *devinfo; 1409 1410 down_read(&__i2c_board_lock); 1411 list_for_each_entry(devinfo, &__i2c_board_list, list) { 1412 if (devinfo->busnum == adapter->nr && 1413 IS_ERR(i2c_new_client_device(adapter, &devinfo->board_info))) 1414 dev_err(&adapter->dev, 1415 "Can't create device at 0x%02x\n", 1416 devinfo->board_info.addr); 1417 } 1418 up_read(&__i2c_board_lock); 1419 } 1420 1421 static int i2c_do_add_adapter(struct i2c_driver *driver, 1422 struct i2c_adapter *adap) 1423 { 1424 /* Detect supported devices on that bus, and instantiate them */ 1425 i2c_detect(adap, driver); 1426 1427 return 0; 1428 } 1429 1430 static int __process_new_adapter(struct device_driver *d, void *data) 1431 { 1432 return i2c_do_add_adapter(to_i2c_driver(d), data); 1433 } 1434 1435 static const struct i2c_lock_operations i2c_adapter_lock_ops = { 1436 .lock_bus = i2c_adapter_lock_bus, 1437 .trylock_bus = i2c_adapter_trylock_bus, 1438 .unlock_bus = i2c_adapter_unlock_bus, 1439 }; 1440 1441 static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap) 1442 { 1443 struct irq_domain *domain = adap->host_notify_domain; 1444 irq_hw_number_t hwirq; 1445 1446 if (!domain) 1447 return; 1448 1449 for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++) 1450 irq_dispose_mapping(irq_find_mapping(domain, hwirq)); 1451 1452 irq_domain_remove(domain); 1453 adap->host_notify_domain = NULL; 1454 } 1455 1456 static int i2c_host_notify_irq_map(struct irq_domain *h, 1457 unsigned int virq, 1458 irq_hw_number_t hw_irq_num) 1459 { 1460 irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq); 1461 1462 return 0; 1463 } 1464 1465 static const struct irq_domain_ops i2c_host_notify_irq_ops = { 1466 .map = i2c_host_notify_irq_map, 1467 }; 1468 1469 static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap) 1470 { 1471 struct irq_domain *domain; 1472 1473 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY)) 1474 return 0; 1475 1476 domain = irq_domain_create_linear(adap->dev.parent->fwnode, 1477 I2C_ADDR_7BITS_COUNT, 1478 &i2c_host_notify_irq_ops, adap); 1479 if (!domain) 1480 return -ENOMEM; 1481 1482 adap->host_notify_domain = domain; 1483 1484 return 0; 1485 } 1486 1487 /** 1488 * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct 1489 * I2C client. 1490 * @adap: the adapter 1491 * @addr: the I2C address of the notifying device 1492 * Context: can't sleep 1493 * 1494 * Helper function to be called from an I2C bus driver's interrupt 1495 * handler. It will schedule the Host Notify IRQ. 1496 */ 1497 int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr) 1498 { 1499 int irq; 1500 1501 if (!adap) 1502 return -EINVAL; 1503 1504 dev_dbg(&adap->dev, "Detected HostNotify from address 0x%02x", addr); 1505 1506 irq = irq_find_mapping(adap->host_notify_domain, addr); 1507 if (irq <= 0) 1508 return -ENXIO; 1509 1510 generic_handle_irq_safe(irq); 1511 1512 return 0; 1513 } 1514 EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify); 1515 1516 static int i2c_register_adapter(struct i2c_adapter *adap) 1517 { 1518 int res = -EINVAL; 1519 1520 /* Can't register until after driver model init */ 1521 if (WARN_ON(!is_registered)) { 1522 res = -EAGAIN; 1523 goto out_list; 1524 } 1525 1526 /* Sanity checks */ 1527 if (WARN(!adap->name[0], "i2c adapter has no name")) 1528 goto out_list; 1529 1530 if (!adap->algo) { 1531 pr_err("adapter '%s': no algo supplied!\n", adap->name); 1532 goto out_list; 1533 } 1534 1535 if (!adap->lock_ops) 1536 adap->lock_ops = &i2c_adapter_lock_ops; 1537 1538 adap->locked_flags = 0; 1539 rt_mutex_init(&adap->bus_lock); 1540 rt_mutex_init(&adap->mux_lock); 1541 mutex_init(&adap->userspace_clients_lock); 1542 INIT_LIST_HEAD(&adap->userspace_clients); 1543 1544 /* Set default timeout to 1 second if not already set */ 1545 if (adap->timeout == 0) 1546 adap->timeout = HZ; 1547 1548 /* register soft irqs for Host Notify */ 1549 res = i2c_setup_host_notify_irq_domain(adap); 1550 if (res) { 1551 pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n", 1552 adap->name, res); 1553 goto out_list; 1554 } 1555 1556 dev_set_name(&adap->dev, "i2c-%d", adap->nr); 1557 adap->dev.bus = &i2c_bus_type; 1558 adap->dev.type = &i2c_adapter_type; 1559 device_initialize(&adap->dev); 1560 1561 /* 1562 * This adapter can be used as a parent immediately after device_add(), 1563 * setup runtime-pm (especially ignore-children) before hand. 1564 */ 1565 device_enable_async_suspend(&adap->dev); 1566 pm_runtime_no_callbacks(&adap->dev); 1567 pm_suspend_ignore_children(&adap->dev, true); 1568 pm_runtime_enable(&adap->dev); 1569 1570 res = device_add(&adap->dev); 1571 if (res) { 1572 pr_err("adapter '%s': can't register device (%d)\n", adap->name, res); 1573 put_device(&adap->dev); 1574 goto out_list; 1575 } 1576 1577 adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root); 1578 1579 res = i2c_setup_smbus_alert(adap); 1580 if (res) 1581 goto out_reg; 1582 1583 res = i2c_init_recovery(adap); 1584 if (res == -EPROBE_DEFER) 1585 goto out_reg; 1586 1587 dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name); 1588 1589 /* create pre-declared device nodes */ 1590 of_i2c_register_devices(adap); 1591 i2c_acpi_install_space_handler(adap); 1592 i2c_acpi_register_devices(adap); 1593 1594 if (adap->nr < __i2c_first_dynamic_bus_num) 1595 i2c_scan_static_board_info(adap); 1596 1597 /* Notify drivers */ 1598 mutex_lock(&core_lock); 1599 bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter); 1600 mutex_unlock(&core_lock); 1601 1602 return 0; 1603 1604 out_reg: 1605 debugfs_remove_recursive(adap->debugfs); 1606 init_completion(&adap->dev_released); 1607 device_unregister(&adap->dev); 1608 wait_for_completion(&adap->dev_released); 1609 out_list: 1610 mutex_lock(&core_lock); 1611 idr_remove(&i2c_adapter_idr, adap->nr); 1612 mutex_unlock(&core_lock); 1613 return res; 1614 } 1615 1616 /** 1617 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1 1618 * @adap: the adapter to register (with adap->nr initialized) 1619 * Context: can sleep 1620 * 1621 * See i2c_add_numbered_adapter() for details. 1622 */ 1623 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap) 1624 { 1625 int id; 1626 1627 mutex_lock(&core_lock); 1628 id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL); 1629 mutex_unlock(&core_lock); 1630 if (WARN(id < 0, "couldn't get idr")) 1631 return id == -ENOSPC ? -EBUSY : id; 1632 1633 return i2c_register_adapter(adap); 1634 } 1635 1636 /** 1637 * i2c_add_adapter - declare i2c adapter, use dynamic bus number 1638 * @adapter: the adapter to add 1639 * Context: can sleep 1640 * 1641 * This routine is used to declare an I2C adapter when its bus number 1642 * doesn't matter or when its bus number is specified by an dt alias. 1643 * Examples of bases when the bus number doesn't matter: I2C adapters 1644 * dynamically added by USB links or PCI plugin cards. 1645 * 1646 * When this returns zero, a new bus number was allocated and stored 1647 * in adap->nr, and the specified adapter became available for clients. 1648 * Otherwise, a negative errno value is returned. 1649 */ 1650 int i2c_add_adapter(struct i2c_adapter *adapter) 1651 { 1652 struct device *dev = &adapter->dev; 1653 int id; 1654 1655 id = of_alias_get_id(dev->of_node, "i2c"); 1656 if (id >= 0) { 1657 adapter->nr = id; 1658 return __i2c_add_numbered_adapter(adapter); 1659 } 1660 1661 mutex_lock(&core_lock); 1662 id = idr_alloc(&i2c_adapter_idr, adapter, 1663 __i2c_first_dynamic_bus_num, 0, GFP_KERNEL); 1664 mutex_unlock(&core_lock); 1665 if (WARN(id < 0, "couldn't get idr")) 1666 return id; 1667 1668 adapter->nr = id; 1669 1670 return i2c_register_adapter(adapter); 1671 } 1672 EXPORT_SYMBOL(i2c_add_adapter); 1673 1674 /** 1675 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number 1676 * @adap: the adapter to register (with adap->nr initialized) 1677 * Context: can sleep 1678 * 1679 * This routine is used to declare an I2C adapter when its bus number 1680 * matters. For example, use it for I2C adapters from system-on-chip CPUs, 1681 * or otherwise built in to the system's mainboard, and where i2c_board_info 1682 * is used to properly configure I2C devices. 1683 * 1684 * If the requested bus number is set to -1, then this function will behave 1685 * identically to i2c_add_adapter, and will dynamically assign a bus number. 1686 * 1687 * If no devices have pre-been declared for this bus, then be sure to 1688 * register the adapter before any dynamically allocated ones. Otherwise 1689 * the required bus ID may not be available. 1690 * 1691 * When this returns zero, the specified adapter became available for 1692 * clients using the bus number provided in adap->nr. Also, the table 1693 * of I2C devices pre-declared using i2c_register_board_info() is scanned, 1694 * and the appropriate driver model device nodes are created. Otherwise, a 1695 * negative errno value is returned. 1696 */ 1697 int i2c_add_numbered_adapter(struct i2c_adapter *adap) 1698 { 1699 if (adap->nr == -1) /* -1 means dynamically assign bus id */ 1700 return i2c_add_adapter(adap); 1701 1702 return __i2c_add_numbered_adapter(adap); 1703 } 1704 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter); 1705 1706 static void i2c_do_del_adapter(struct i2c_driver *driver, 1707 struct i2c_adapter *adapter) 1708 { 1709 struct i2c_client *client, *_n; 1710 1711 /* Remove the devices we created ourselves as the result of hardware 1712 * probing (using a driver's detect method) */ 1713 list_for_each_entry_safe(client, _n, &driver->clients, detected) { 1714 if (client->adapter == adapter) { 1715 dev_dbg(&adapter->dev, "Removing %s at 0x%x\n", 1716 client->name, client->addr); 1717 list_del(&client->detected); 1718 i2c_unregister_device(client); 1719 } 1720 } 1721 } 1722 1723 static int __unregister_client(struct device *dev, void *dummy) 1724 { 1725 struct i2c_client *client = i2c_verify_client(dev); 1726 if (client && strcmp(client->name, "dummy")) 1727 i2c_unregister_device(client); 1728 return 0; 1729 } 1730 1731 static int __unregister_dummy(struct device *dev, void *dummy) 1732 { 1733 struct i2c_client *client = i2c_verify_client(dev); 1734 i2c_unregister_device(client); 1735 return 0; 1736 } 1737 1738 static int __process_removed_adapter(struct device_driver *d, void *data) 1739 { 1740 i2c_do_del_adapter(to_i2c_driver(d), data); 1741 return 0; 1742 } 1743 1744 /** 1745 * i2c_del_adapter - unregister I2C adapter 1746 * @adap: the adapter being unregistered 1747 * Context: can sleep 1748 * 1749 * This unregisters an I2C adapter which was previously registered 1750 * by @i2c_add_adapter or @i2c_add_numbered_adapter. 1751 */ 1752 void i2c_del_adapter(struct i2c_adapter *adap) 1753 { 1754 struct i2c_adapter *found; 1755 struct i2c_client *client, *next; 1756 1757 /* First make sure that this adapter was ever added */ 1758 mutex_lock(&core_lock); 1759 found = idr_find(&i2c_adapter_idr, adap->nr); 1760 mutex_unlock(&core_lock); 1761 if (found != adap) { 1762 pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name); 1763 return; 1764 } 1765 1766 i2c_acpi_remove_space_handler(adap); 1767 /* Tell drivers about this removal */ 1768 mutex_lock(&core_lock); 1769 bus_for_each_drv(&i2c_bus_type, NULL, adap, 1770 __process_removed_adapter); 1771 mutex_unlock(&core_lock); 1772 1773 /* Remove devices instantiated from sysfs */ 1774 mutex_lock_nested(&adap->userspace_clients_lock, 1775 i2c_adapter_depth(adap)); 1776 list_for_each_entry_safe(client, next, &adap->userspace_clients, 1777 detected) { 1778 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name, 1779 client->addr); 1780 list_del(&client->detected); 1781 i2c_unregister_device(client); 1782 } 1783 mutex_unlock(&adap->userspace_clients_lock); 1784 1785 /* Detach any active clients. This can't fail, thus we do not 1786 * check the returned value. This is a two-pass process, because 1787 * we can't remove the dummy devices during the first pass: they 1788 * could have been instantiated by real devices wishing to clean 1789 * them up properly, so we give them a chance to do that first. */ 1790 device_for_each_child(&adap->dev, NULL, __unregister_client); 1791 device_for_each_child(&adap->dev, NULL, __unregister_dummy); 1792 1793 /* device name is gone after device_unregister */ 1794 dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name); 1795 1796 pm_runtime_disable(&adap->dev); 1797 1798 i2c_host_notify_irq_teardown(adap); 1799 1800 debugfs_remove_recursive(adap->debugfs); 1801 1802 /* wait until all references to the device are gone 1803 * 1804 * FIXME: This is old code and should ideally be replaced by an 1805 * alternative which results in decoupling the lifetime of the struct 1806 * device from the i2c_adapter, like spi or netdev do. Any solution 1807 * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled! 1808 */ 1809 init_completion(&adap->dev_released); 1810 device_unregister(&adap->dev); 1811 wait_for_completion(&adap->dev_released); 1812 1813 /* free bus id */ 1814 mutex_lock(&core_lock); 1815 idr_remove(&i2c_adapter_idr, adap->nr); 1816 mutex_unlock(&core_lock); 1817 1818 /* Clear the device structure in case this adapter is ever going to be 1819 added again */ 1820 memset(&adap->dev, 0, sizeof(adap->dev)); 1821 } 1822 EXPORT_SYMBOL(i2c_del_adapter); 1823 1824 static void devm_i2c_del_adapter(void *adapter) 1825 { 1826 i2c_del_adapter(adapter); 1827 } 1828 1829 /** 1830 * devm_i2c_add_adapter - device-managed variant of i2c_add_adapter() 1831 * @dev: managing device for adding this I2C adapter 1832 * @adapter: the adapter to add 1833 * Context: can sleep 1834 * 1835 * Add adapter with dynamic bus number, same with i2c_add_adapter() 1836 * but the adapter will be auto deleted on driver detach. 1837 */ 1838 int devm_i2c_add_adapter(struct device *dev, struct i2c_adapter *adapter) 1839 { 1840 int ret; 1841 1842 ret = i2c_add_adapter(adapter); 1843 if (ret) 1844 return ret; 1845 1846 return devm_add_action_or_reset(dev, devm_i2c_del_adapter, adapter); 1847 } 1848 EXPORT_SYMBOL_GPL(devm_i2c_add_adapter); 1849 1850 static int i2c_dev_or_parent_fwnode_match(struct device *dev, const void *data) 1851 { 1852 if (dev_fwnode(dev) == data) 1853 return 1; 1854 1855 if (dev->parent && dev_fwnode(dev->parent) == data) 1856 return 1; 1857 1858 return 0; 1859 } 1860 1861 /** 1862 * i2c_find_adapter_by_fwnode() - find an i2c_adapter for the fwnode 1863 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter 1864 * 1865 * Look up and return the &struct i2c_adapter corresponding to the @fwnode. 1866 * If no adapter can be found, or @fwnode is NULL, this returns NULL. 1867 * 1868 * The user must call put_device(&adapter->dev) once done with the i2c adapter. 1869 */ 1870 struct i2c_adapter *i2c_find_adapter_by_fwnode(struct fwnode_handle *fwnode) 1871 { 1872 struct i2c_adapter *adapter; 1873 struct device *dev; 1874 1875 if (!fwnode) 1876 return NULL; 1877 1878 dev = bus_find_device(&i2c_bus_type, NULL, fwnode, 1879 i2c_dev_or_parent_fwnode_match); 1880 if (!dev) 1881 return NULL; 1882 1883 adapter = i2c_verify_adapter(dev); 1884 if (!adapter) 1885 put_device(dev); 1886 1887 return adapter; 1888 } 1889 EXPORT_SYMBOL(i2c_find_adapter_by_fwnode); 1890 1891 /** 1892 * i2c_get_adapter_by_fwnode() - find an i2c_adapter for the fwnode 1893 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter 1894 * 1895 * Look up and return the &struct i2c_adapter corresponding to the @fwnode, 1896 * and increment the adapter module's use count. If no adapter can be found, 1897 * or @fwnode is NULL, this returns NULL. 1898 * 1899 * The user must call i2c_put_adapter(adapter) once done with the i2c adapter. 1900 * Note that this is different from i2c_find_adapter_by_node(). 1901 */ 1902 struct i2c_adapter *i2c_get_adapter_by_fwnode(struct fwnode_handle *fwnode) 1903 { 1904 struct i2c_adapter *adapter; 1905 1906 adapter = i2c_find_adapter_by_fwnode(fwnode); 1907 if (!adapter) 1908 return NULL; 1909 1910 if (!try_module_get(adapter->owner)) { 1911 put_device(&adapter->dev); 1912 adapter = NULL; 1913 } 1914 1915 return adapter; 1916 } 1917 EXPORT_SYMBOL(i2c_get_adapter_by_fwnode); 1918 1919 static void i2c_parse_timing(struct device *dev, char *prop_name, u32 *cur_val_p, 1920 u32 def_val, bool use_def) 1921 { 1922 int ret; 1923 1924 ret = device_property_read_u32(dev, prop_name, cur_val_p); 1925 if (ret && use_def) 1926 *cur_val_p = def_val; 1927 1928 dev_dbg(dev, "%s: %u\n", prop_name, *cur_val_p); 1929 } 1930 1931 /** 1932 * i2c_parse_fw_timings - get I2C related timing parameters from firmware 1933 * @dev: The device to scan for I2C timing properties 1934 * @t: the i2c_timings struct to be filled with values 1935 * @use_defaults: bool to use sane defaults derived from the I2C specification 1936 * when properties are not found, otherwise don't update 1937 * 1938 * Scan the device for the generic I2C properties describing timing parameters 1939 * for the signal and fill the given struct with the results. If a property was 1940 * not found and use_defaults was true, then maximum timings are assumed which 1941 * are derived from the I2C specification. If use_defaults is not used, the 1942 * results will be as before, so drivers can apply their own defaults before 1943 * calling this helper. The latter is mainly intended for avoiding regressions 1944 * of existing drivers which want to switch to this function. New drivers 1945 * almost always should use the defaults. 1946 */ 1947 void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults) 1948 { 1949 bool u = use_defaults; 1950 u32 d; 1951 1952 i2c_parse_timing(dev, "clock-frequency", &t->bus_freq_hz, 1953 I2C_MAX_STANDARD_MODE_FREQ, u); 1954 1955 d = t->bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ ? 1000 : 1956 t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120; 1957 i2c_parse_timing(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns, d, u); 1958 1959 d = t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120; 1960 i2c_parse_timing(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns, d, u); 1961 1962 i2c_parse_timing(dev, "i2c-scl-internal-delay-ns", 1963 &t->scl_int_delay_ns, 0, u); 1964 i2c_parse_timing(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns, 1965 t->scl_fall_ns, u); 1966 i2c_parse_timing(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns, 0, u); 1967 i2c_parse_timing(dev, "i2c-digital-filter-width-ns", 1968 &t->digital_filter_width_ns, 0, u); 1969 i2c_parse_timing(dev, "i2c-analog-filter-cutoff-frequency", 1970 &t->analog_filter_cutoff_freq_hz, 0, u); 1971 } 1972 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings); 1973 1974 /* ------------------------------------------------------------------------- */ 1975 1976 int i2c_for_each_dev(void *data, int (*fn)(struct device *dev, void *data)) 1977 { 1978 int res; 1979 1980 mutex_lock(&core_lock); 1981 res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn); 1982 mutex_unlock(&core_lock); 1983 1984 return res; 1985 } 1986 EXPORT_SYMBOL_GPL(i2c_for_each_dev); 1987 1988 static int __process_new_driver(struct device *dev, void *data) 1989 { 1990 if (dev->type != &i2c_adapter_type) 1991 return 0; 1992 return i2c_do_add_adapter(data, to_i2c_adapter(dev)); 1993 } 1994 1995 /* 1996 * An i2c_driver is used with one or more i2c_client (device) nodes to access 1997 * i2c slave chips, on a bus instance associated with some i2c_adapter. 1998 */ 1999 2000 int i2c_register_driver(struct module *owner, struct i2c_driver *driver) 2001 { 2002 int res; 2003 2004 /* Can't register until after driver model init */ 2005 if (WARN_ON(!is_registered)) 2006 return -EAGAIN; 2007 2008 /* add the driver to the list of i2c drivers in the driver core */ 2009 driver->driver.owner = owner; 2010 driver->driver.bus = &i2c_bus_type; 2011 INIT_LIST_HEAD(&driver->clients); 2012 2013 /* When registration returns, the driver core 2014 * will have called probe() for all matching-but-unbound devices. 2015 */ 2016 res = driver_register(&driver->driver); 2017 if (res) 2018 return res; 2019 2020 pr_debug("driver [%s] registered\n", driver->driver.name); 2021 2022 /* Walk the adapters that are already present */ 2023 i2c_for_each_dev(driver, __process_new_driver); 2024 2025 return 0; 2026 } 2027 EXPORT_SYMBOL(i2c_register_driver); 2028 2029 static int __process_removed_driver(struct device *dev, void *data) 2030 { 2031 if (dev->type == &i2c_adapter_type) 2032 i2c_do_del_adapter(data, to_i2c_adapter(dev)); 2033 return 0; 2034 } 2035 2036 /** 2037 * i2c_del_driver - unregister I2C driver 2038 * @driver: the driver being unregistered 2039 * Context: can sleep 2040 */ 2041 void i2c_del_driver(struct i2c_driver *driver) 2042 { 2043 i2c_for_each_dev(driver, __process_removed_driver); 2044 2045 driver_unregister(&driver->driver); 2046 pr_debug("driver [%s] unregistered\n", driver->driver.name); 2047 } 2048 EXPORT_SYMBOL(i2c_del_driver); 2049 2050 /* ------------------------------------------------------------------------- */ 2051 2052 struct i2c_cmd_arg { 2053 unsigned cmd; 2054 void *arg; 2055 }; 2056 2057 static int i2c_cmd(struct device *dev, void *_arg) 2058 { 2059 struct i2c_client *client = i2c_verify_client(dev); 2060 struct i2c_cmd_arg *arg = _arg; 2061 struct i2c_driver *driver; 2062 2063 if (!client || !client->dev.driver) 2064 return 0; 2065 2066 driver = to_i2c_driver(client->dev.driver); 2067 if (driver->command) 2068 driver->command(client, arg->cmd, arg->arg); 2069 return 0; 2070 } 2071 2072 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg) 2073 { 2074 struct i2c_cmd_arg cmd_arg; 2075 2076 cmd_arg.cmd = cmd; 2077 cmd_arg.arg = arg; 2078 device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd); 2079 } 2080 EXPORT_SYMBOL(i2c_clients_command); 2081 2082 static int __init i2c_init(void) 2083 { 2084 int retval; 2085 2086 retval = of_alias_get_highest_id("i2c"); 2087 2088 down_write(&__i2c_board_lock); 2089 if (retval >= __i2c_first_dynamic_bus_num) 2090 __i2c_first_dynamic_bus_num = retval + 1; 2091 up_write(&__i2c_board_lock); 2092 2093 retval = bus_register(&i2c_bus_type); 2094 if (retval) 2095 return retval; 2096 2097 is_registered = true; 2098 2099 i2c_debugfs_root = debugfs_create_dir("i2c", NULL); 2100 2101 retval = i2c_add_driver(&dummy_driver); 2102 if (retval) 2103 goto class_err; 2104 2105 if (IS_ENABLED(CONFIG_OF_DYNAMIC)) 2106 WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier)); 2107 if (IS_ENABLED(CONFIG_ACPI)) 2108 WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier)); 2109 2110 return 0; 2111 2112 class_err: 2113 is_registered = false; 2114 bus_unregister(&i2c_bus_type); 2115 return retval; 2116 } 2117 2118 static void __exit i2c_exit(void) 2119 { 2120 if (IS_ENABLED(CONFIG_ACPI)) 2121 WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier)); 2122 if (IS_ENABLED(CONFIG_OF_DYNAMIC)) 2123 WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier)); 2124 i2c_del_driver(&dummy_driver); 2125 debugfs_remove_recursive(i2c_debugfs_root); 2126 bus_unregister(&i2c_bus_type); 2127 tracepoint_synchronize_unregister(); 2128 } 2129 2130 /* We must initialize early, because some subsystems register i2c drivers 2131 * in subsys_initcall() code, but are linked (and initialized) before i2c. 2132 */ 2133 postcore_initcall(i2c_init); 2134 module_exit(i2c_exit); 2135 2136 /* ---------------------------------------------------- 2137 * the functional interface to the i2c busses. 2138 * ---------------------------------------------------- 2139 */ 2140 2141 /* Check if val is exceeding the quirk IFF quirk is non 0 */ 2142 #define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk))) 2143 2144 static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg) 2145 { 2146 dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n", 2147 err_msg, msg->addr, msg->len, 2148 str_read_write(msg->flags & I2C_M_RD)); 2149 return -EOPNOTSUPP; 2150 } 2151 2152 static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 2153 { 2154 const struct i2c_adapter_quirks *q = adap->quirks; 2155 int max_num = q->max_num_msgs, i; 2156 bool do_len_check = true; 2157 2158 if (q->flags & I2C_AQ_COMB) { 2159 max_num = 2; 2160 2161 /* special checks for combined messages */ 2162 if (num == 2) { 2163 if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD) 2164 return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write"); 2165 2166 if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD)) 2167 return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read"); 2168 2169 if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr) 2170 return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr"); 2171 2172 if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len)) 2173 return i2c_quirk_error(adap, &msgs[0], "msg too long"); 2174 2175 if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len)) 2176 return i2c_quirk_error(adap, &msgs[1], "msg too long"); 2177 2178 do_len_check = false; 2179 } 2180 } 2181 2182 if (i2c_quirk_exceeded(num, max_num)) 2183 return i2c_quirk_error(adap, &msgs[0], "too many messages"); 2184 2185 for (i = 0; i < num; i++) { 2186 u16 len = msgs[i].len; 2187 2188 if (msgs[i].flags & I2C_M_RD) { 2189 if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len)) 2190 return i2c_quirk_error(adap, &msgs[i], "msg too long"); 2191 2192 if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0) 2193 return i2c_quirk_error(adap, &msgs[i], "no zero length"); 2194 } else { 2195 if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len)) 2196 return i2c_quirk_error(adap, &msgs[i], "msg too long"); 2197 2198 if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0) 2199 return i2c_quirk_error(adap, &msgs[i], "no zero length"); 2200 } 2201 } 2202 2203 return 0; 2204 } 2205 2206 /** 2207 * __i2c_transfer - unlocked flavor of i2c_transfer 2208 * @adap: Handle to I2C bus 2209 * @msgs: One or more messages to execute before STOP is issued to 2210 * terminate the operation; each message begins with a START. 2211 * @num: Number of messages to be executed. 2212 * 2213 * Returns negative errno, else the number of messages executed. 2214 * 2215 * Adapter lock must be held when calling this function. No debug logging 2216 * takes place. 2217 */ 2218 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 2219 { 2220 unsigned long orig_jiffies; 2221 int ret, try; 2222 2223 if (!adap->algo->master_xfer) { 2224 dev_dbg(&adap->dev, "I2C level transfers not supported\n"); 2225 return -EOPNOTSUPP; 2226 } 2227 2228 if (WARN_ON(!msgs || num < 1)) 2229 return -EINVAL; 2230 2231 ret = __i2c_check_suspended(adap); 2232 if (ret) 2233 return ret; 2234 2235 if (adap->quirks && i2c_check_for_quirks(adap, msgs, num)) 2236 return -EOPNOTSUPP; 2237 2238 /* 2239 * i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets 2240 * enabled. This is an efficient way of keeping the for-loop from 2241 * being executed when not needed. 2242 */ 2243 if (static_branch_unlikely(&i2c_trace_msg_key)) { 2244 int i; 2245 for (i = 0; i < num; i++) 2246 if (msgs[i].flags & I2C_M_RD) 2247 trace_i2c_read(adap, &msgs[i], i); 2248 else 2249 trace_i2c_write(adap, &msgs[i], i); 2250 } 2251 2252 /* Retry automatically on arbitration loss */ 2253 orig_jiffies = jiffies; 2254 for (ret = 0, try = 0; try <= adap->retries; try++) { 2255 if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic) 2256 ret = adap->algo->master_xfer_atomic(adap, msgs, num); 2257 else 2258 ret = adap->algo->master_xfer(adap, msgs, num); 2259 2260 if (ret != -EAGAIN) 2261 break; 2262 if (time_after(jiffies, orig_jiffies + adap->timeout)) 2263 break; 2264 } 2265 2266 if (static_branch_unlikely(&i2c_trace_msg_key)) { 2267 int i; 2268 for (i = 0; i < ret; i++) 2269 if (msgs[i].flags & I2C_M_RD) 2270 trace_i2c_reply(adap, &msgs[i], i); 2271 trace_i2c_result(adap, num, ret); 2272 } 2273 2274 return ret; 2275 } 2276 EXPORT_SYMBOL(__i2c_transfer); 2277 2278 /** 2279 * i2c_transfer - execute a single or combined I2C message 2280 * @adap: Handle to I2C bus 2281 * @msgs: One or more messages to execute before STOP is issued to 2282 * terminate the operation; each message begins with a START. 2283 * @num: Number of messages to be executed. 2284 * 2285 * Returns negative errno, else the number of messages executed. 2286 * 2287 * Note that there is no requirement that each message be sent to 2288 * the same slave address, although that is the most common model. 2289 */ 2290 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 2291 { 2292 int ret; 2293 2294 /* REVISIT the fault reporting model here is weak: 2295 * 2296 * - When we get an error after receiving N bytes from a slave, 2297 * there is no way to report "N". 2298 * 2299 * - When we get a NAK after transmitting N bytes to a slave, 2300 * there is no way to report "N" ... or to let the master 2301 * continue executing the rest of this combined message, if 2302 * that's the appropriate response. 2303 * 2304 * - When for example "num" is two and we successfully complete 2305 * the first message but get an error part way through the 2306 * second, it's unclear whether that should be reported as 2307 * one (discarding status on the second message) or errno 2308 * (discarding status on the first one). 2309 */ 2310 ret = __i2c_lock_bus_helper(adap); 2311 if (ret) 2312 return ret; 2313 2314 ret = __i2c_transfer(adap, msgs, num); 2315 i2c_unlock_bus(adap, I2C_LOCK_SEGMENT); 2316 2317 return ret; 2318 } 2319 EXPORT_SYMBOL(i2c_transfer); 2320 2321 /** 2322 * i2c_transfer_buffer_flags - issue a single I2C message transferring data 2323 * to/from a buffer 2324 * @client: Handle to slave device 2325 * @buf: Where the data is stored 2326 * @count: How many bytes to transfer, must be less than 64k since msg.len is u16 2327 * @flags: The flags to be used for the message, e.g. I2C_M_RD for reads 2328 * 2329 * Returns negative errno, or else the number of bytes transferred. 2330 */ 2331 int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf, 2332 int count, u16 flags) 2333 { 2334 int ret; 2335 struct i2c_msg msg = { 2336 .addr = client->addr, 2337 .flags = flags | (client->flags & I2C_M_TEN), 2338 .len = count, 2339 .buf = buf, 2340 }; 2341 2342 ret = i2c_transfer(client->adapter, &msg, 1); 2343 2344 /* 2345 * If everything went ok (i.e. 1 msg transferred), return #bytes 2346 * transferred, else error code. 2347 */ 2348 return (ret == 1) ? count : ret; 2349 } 2350 EXPORT_SYMBOL(i2c_transfer_buffer_flags); 2351 2352 /** 2353 * i2c_get_device_id - get manufacturer, part id and die revision of a device 2354 * @client: The device to query 2355 * @id: The queried information 2356 * 2357 * Returns negative errno on error, zero on success. 2358 */ 2359 int i2c_get_device_id(const struct i2c_client *client, 2360 struct i2c_device_identity *id) 2361 { 2362 struct i2c_adapter *adap = client->adapter; 2363 union i2c_smbus_data raw_id; 2364 int ret; 2365 2366 if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) 2367 return -EOPNOTSUPP; 2368 2369 raw_id.block[0] = 3; 2370 ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0, 2371 I2C_SMBUS_READ, client->addr << 1, 2372 I2C_SMBUS_I2C_BLOCK_DATA, &raw_id); 2373 if (ret) 2374 return ret; 2375 2376 id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4); 2377 id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3); 2378 id->die_revision = raw_id.block[3] & 0x7; 2379 return 0; 2380 } 2381 EXPORT_SYMBOL_GPL(i2c_get_device_id); 2382 2383 /** 2384 * i2c_client_get_device_id - get the driver match table entry of a device 2385 * @client: the device to query. The device must be bound to a driver 2386 * 2387 * Returns a pointer to the matching entry if found, NULL otherwise. 2388 */ 2389 const struct i2c_device_id *i2c_client_get_device_id(const struct i2c_client *client) 2390 { 2391 const struct i2c_driver *drv = to_i2c_driver(client->dev.driver); 2392 2393 return i2c_match_id(drv->id_table, client); 2394 } 2395 EXPORT_SYMBOL_GPL(i2c_client_get_device_id); 2396 2397 /* ---------------------------------------------------- 2398 * the i2c address scanning function 2399 * Will not work for 10-bit addresses! 2400 * ---------------------------------------------------- 2401 */ 2402 2403 /* 2404 * Legacy default probe function, mostly relevant for SMBus. The default 2405 * probe method is a quick write, but it is known to corrupt the 24RF08 2406 * EEPROMs due to a state machine bug, and could also irreversibly 2407 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f, 2408 * we use a short byte read instead. Also, some bus drivers don't implement 2409 * quick write, so we fallback to a byte read in that case too. 2410 * On x86, there is another special case for FSC hardware monitoring chips, 2411 * which want regular byte reads (address 0x73.) Fortunately, these are the 2412 * only known chips using this I2C address on PC hardware. 2413 * Returns 1 if probe succeeded, 0 if not. 2414 */ 2415 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr) 2416 { 2417 int err; 2418 union i2c_smbus_data dummy; 2419 2420 #ifdef CONFIG_X86 2421 if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON) 2422 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA)) 2423 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, 2424 I2C_SMBUS_BYTE_DATA, &dummy); 2425 else 2426 #endif 2427 if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50) 2428 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK)) 2429 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0, 2430 I2C_SMBUS_QUICK, NULL); 2431 else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE)) 2432 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, 2433 I2C_SMBUS_BYTE, &dummy); 2434 else { 2435 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n", 2436 addr); 2437 err = -EOPNOTSUPP; 2438 } 2439 2440 return err >= 0; 2441 } 2442 2443 static int i2c_detect_address(struct i2c_client *temp_client, 2444 struct i2c_driver *driver) 2445 { 2446 struct i2c_board_info info; 2447 struct i2c_adapter *adapter = temp_client->adapter; 2448 int addr = temp_client->addr; 2449 int err; 2450 2451 /* Make sure the address is valid */ 2452 err = i2c_check_7bit_addr_validity_strict(addr); 2453 if (err) { 2454 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n", 2455 addr); 2456 return err; 2457 } 2458 2459 /* Skip if already in use (7 bit, no need to encode flags) */ 2460 if (i2c_check_addr_busy(adapter, addr)) 2461 return 0; 2462 2463 /* Make sure there is something at this address */ 2464 if (!i2c_default_probe(adapter, addr)) 2465 return 0; 2466 2467 /* Finally call the custom detection function */ 2468 memset(&info, 0, sizeof(struct i2c_board_info)); 2469 info.addr = addr; 2470 err = driver->detect(temp_client, &info); 2471 if (err) { 2472 /* -ENODEV is returned if the detection fails. We catch it 2473 here as this isn't an error. */ 2474 return err == -ENODEV ? 0 : err; 2475 } 2476 2477 /* Consistency check */ 2478 if (info.type[0] == '\0') { 2479 dev_err(&adapter->dev, 2480 "%s detection function provided no name for 0x%x\n", 2481 driver->driver.name, addr); 2482 } else { 2483 struct i2c_client *client; 2484 2485 /* Detection succeeded, instantiate the device */ 2486 if (adapter->class & I2C_CLASS_DEPRECATED) 2487 dev_warn(&adapter->dev, 2488 "This adapter will soon drop class based instantiation of devices. " 2489 "Please make sure client 0x%02x gets instantiated by other means. " 2490 "Check 'Documentation/i2c/instantiating-devices.rst' for details.\n", 2491 info.addr); 2492 2493 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n", 2494 info.type, info.addr); 2495 client = i2c_new_client_device(adapter, &info); 2496 if (!IS_ERR(client)) 2497 list_add_tail(&client->detected, &driver->clients); 2498 else 2499 dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n", 2500 info.type, info.addr); 2501 } 2502 return 0; 2503 } 2504 2505 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver) 2506 { 2507 const unsigned short *address_list; 2508 struct i2c_client *temp_client; 2509 int i, err = 0; 2510 2511 address_list = driver->address_list; 2512 if (!driver->detect || !address_list) 2513 return 0; 2514 2515 /* Warn that the adapter lost class based instantiation */ 2516 if (adapter->class == I2C_CLASS_DEPRECATED) { 2517 dev_dbg(&adapter->dev, 2518 "This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. " 2519 "If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n", 2520 driver->driver.name); 2521 return 0; 2522 } 2523 2524 /* Stop here if the classes do not match */ 2525 if (!(adapter->class & driver->class)) 2526 return 0; 2527 2528 /* Set up a temporary client to help detect callback */ 2529 temp_client = kzalloc(sizeof(*temp_client), GFP_KERNEL); 2530 if (!temp_client) 2531 return -ENOMEM; 2532 2533 temp_client->adapter = adapter; 2534 2535 for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) { 2536 dev_dbg(&adapter->dev, 2537 "found normal entry for adapter %d, addr 0x%02x\n", 2538 i2c_adapter_id(adapter), address_list[i]); 2539 temp_client->addr = address_list[i]; 2540 err = i2c_detect_address(temp_client, driver); 2541 if (unlikely(err)) 2542 break; 2543 } 2544 2545 kfree(temp_client); 2546 2547 return err; 2548 } 2549 2550 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr) 2551 { 2552 return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0, 2553 I2C_SMBUS_QUICK, NULL) >= 0; 2554 } 2555 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read); 2556 2557 struct i2c_client * 2558 i2c_new_scanned_device(struct i2c_adapter *adap, 2559 struct i2c_board_info *info, 2560 unsigned short const *addr_list, 2561 int (*probe)(struct i2c_adapter *adap, unsigned short addr)) 2562 { 2563 int i; 2564 2565 if (!probe) 2566 probe = i2c_default_probe; 2567 2568 for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) { 2569 /* Check address validity */ 2570 if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) { 2571 dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n", 2572 addr_list[i]); 2573 continue; 2574 } 2575 2576 /* Check address availability (7 bit, no need to encode flags) */ 2577 if (i2c_check_addr_busy(adap, addr_list[i])) { 2578 dev_dbg(&adap->dev, 2579 "Address 0x%02x already in use, not probing\n", 2580 addr_list[i]); 2581 continue; 2582 } 2583 2584 /* Test address responsiveness */ 2585 if (probe(adap, addr_list[i])) 2586 break; 2587 } 2588 2589 if (addr_list[i] == I2C_CLIENT_END) { 2590 dev_dbg(&adap->dev, "Probing failed, no device found\n"); 2591 return ERR_PTR(-ENODEV); 2592 } 2593 2594 info->addr = addr_list[i]; 2595 return i2c_new_client_device(adap, info); 2596 } 2597 EXPORT_SYMBOL_GPL(i2c_new_scanned_device); 2598 2599 struct i2c_adapter *i2c_get_adapter(int nr) 2600 { 2601 struct i2c_adapter *adapter; 2602 2603 mutex_lock(&core_lock); 2604 adapter = idr_find(&i2c_adapter_idr, nr); 2605 if (!adapter) 2606 goto exit; 2607 2608 if (try_module_get(adapter->owner)) 2609 get_device(&adapter->dev); 2610 else 2611 adapter = NULL; 2612 2613 exit: 2614 mutex_unlock(&core_lock); 2615 return adapter; 2616 } 2617 EXPORT_SYMBOL(i2c_get_adapter); 2618 2619 void i2c_put_adapter(struct i2c_adapter *adap) 2620 { 2621 if (!adap) 2622 return; 2623 2624 module_put(adap->owner); 2625 /* Should be last, otherwise we risk use-after-free with 'adap' */ 2626 put_device(&adap->dev); 2627 } 2628 EXPORT_SYMBOL(i2c_put_adapter); 2629 2630 /** 2631 * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg 2632 * @msg: the message to be checked 2633 * @threshold: the minimum number of bytes for which using DMA makes sense. 2634 * Should at least be 1. 2635 * 2636 * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO. 2637 * Or a valid pointer to be used with DMA. After use, release it by 2638 * calling i2c_put_dma_safe_msg_buf(). 2639 * 2640 * This function must only be called from process context! 2641 */ 2642 u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold) 2643 { 2644 /* also skip 0-length msgs for bogus thresholds of 0 */ 2645 if (!threshold) 2646 pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n", 2647 msg->addr); 2648 if (msg->len < threshold || msg->len == 0) 2649 return NULL; 2650 2651 if (msg->flags & I2C_M_DMA_SAFE) 2652 return msg->buf; 2653 2654 pr_debug("using bounce buffer for addr=0x%02x, len=%d\n", 2655 msg->addr, msg->len); 2656 2657 if (msg->flags & I2C_M_RD) 2658 return kzalloc(msg->len, GFP_KERNEL); 2659 else 2660 return kmemdup(msg->buf, msg->len, GFP_KERNEL); 2661 } 2662 EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf); 2663 2664 /** 2665 * i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg 2666 * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL. 2667 * @msg: the message which the buffer corresponds to 2668 * @xferred: bool saying if the message was transferred 2669 */ 2670 void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred) 2671 { 2672 if (!buf || buf == msg->buf) 2673 return; 2674 2675 if (xferred && msg->flags & I2C_M_RD) 2676 memcpy(msg->buf, buf, msg->len); 2677 2678 kfree(buf); 2679 } 2680 EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf); 2681 2682 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>"); 2683 MODULE_DESCRIPTION("I2C-Bus main module"); 2684 MODULE_LICENSE("GPL"); 2685