drivers/i2c/i2c-core-base.c

   1 /*
   2  * Linux I2C core
   3  *
   4  * Copyright (C) 1995-99 Simon G. Vogl
   5  *   With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
   6  *   Mux support by Rodolfo Giometti <giometti@enneenne.com> and
   7  *   Michael Lawnick <michael.lawnick.ext@nsn.com>
   8  *
   9  * Copyright (C) 2013-2017 Wolfram Sang <wsa@the-dreams.de>
  10  *
  11  * This program is free software; you can redistribute it and/or modify it
  12  * under the terms of the GNU General Public License as published by the Free
  13  * Software Foundation; either version 2 of the License, or (at your option)
  14  * any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful, but WITHOUT
  17  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  18  * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
  19  */
  20
  21 #define pr_fmt(fmt) "i2c-core: " fmt
  22
  23 #include <dt-bindings/i2c/i2c.h>
  24 #include <linux/acpi.h>
  25 #include <linux/clk/clk-conf.h>
  26 #include <linux/completion.h>
  27 #include <linux/delay.h>
  28 #include <linux/err.h>
  29 #include <linux/errno.h>
  30 #include <linux/gpio.h>
  31 #include <linux/i2c.h>
  32 #include <linux/idr.h>
  33 #include <linux/init.h>
  34 #include <linux/irqflags.h>
  35 #include <linux/jump_label.h>
  36 #include <linux/kernel.h>
  37 #include <linux/module.h>
  38 #include <linux/mutex.h>
  39 #include <linux/of_device.h>
  40 #include <linux/of.h>
  41 #include <linux/of_irq.h>
  42 #include <linux/pm_domain.h>
  43 #include <linux/pm_runtime.h>
  44 #include <linux/pm_wakeirq.h>
  45 #include <linux/property.h>
  46 #include <linux/rwsem.h>
  47 #include <linux/slab.h>
  48
  49 #include "i2c-core.h"
  50
  51 #define CREATE_TRACE_POINTS
  52 #include <trace/events/i2c.h>
  53
  54 #define I2C_ADDR_OFFSET_TEN_BIT 0xa000
  55 #define I2C_ADDR_OFFSET_SLAVE   0x1000
  56
  57 #define I2C_ADDR_7BITS_MAX      0x77
  58 #define I2C_ADDR_7BITS_COUNT    (I2C_ADDR_7BITS_MAX + 1)
  59
  60 /*
  61  * core_lock protects i2c_adapter_idr, and guarantees that device detection,
  62  * deletion of detected devices, and attach_adapter calls are serialized
  63  */
  64 static DEFINE_MUTEX(core_lock);
  65 static DEFINE_IDR(i2c_adapter_idr);
  66
  67 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
  68
  69 static struct static_key i2c_trace_msg = STATIC_KEY_INIT_FALSE;
  70 static bool is_registered;
  71
  72 int i2c_transfer_trace_reg(void)
  73 {
  74         static_key_slow_inc(&i2c_trace_msg);
  75         return 0;
  76 }
  77
  78 void i2c_transfer_trace_unreg(void)
  79 {
  80         static_key_slow_dec(&i2c_trace_msg);
  81 }
  82
  83 const struct i2c_device_id *i2c_match_id(const struct i2c_device_id *id,
  84                                                 const struct i2c_client *client)
  85 {
  86         if (!(id && client))
  87                 return NULL;
  88
  89         while (id->name[0]) {
  90                 if (strcmp(client->name, id->name) == 0)
  91                         return id;
  92                 id++;
  93         }
  94         return NULL;
  95 }
  96 EXPORT_SYMBOL_GPL(i2c_match_id);
  97
  98 static int i2c_device_match(struct device *dev, struct device_driver *drv)
  99 {
 100         struct i2c_client       *client = i2c_verify_client(dev);
 101         struct i2c_driver       *driver;
 102
 103
 104         /* Attempt an OF style match */
 105         if (i2c_of_match_device(drv->of_match_table, client))
 106                 return 1;
 107
 108         /* Then ACPI style match */
 109         if (acpi_driver_match_device(dev, drv))
 110                 return 1;
 111
 112         driver = to_i2c_driver(drv);
 113
 114         /* Finally an I2C match */
 115         if (i2c_match_id(driver->id_table, client))
 116                 return 1;
 117
 118         return 0;
 119 }
 120
 121 static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
 122 {
 123         struct i2c_client *client = to_i2c_client(dev);
 124         int rc;
 125
 126         rc = acpi_device_uevent_modalias(dev, env);
 127         if (rc != -ENODEV)
 128                 return rc;
 129
 130         return add_uevent_var(env, "MODALIAS=%s%s", I2C_MODULE_PREFIX, client->name);
 131 }
 132
 133 /* i2c bus recovery routines */
 134 static int get_scl_gpio_value(struct i2c_adapter *adap)
 135 {
 136         return gpio_get_value(adap->bus_recovery_info->scl_gpio);
 137 }
 138
 139 static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
 140 {
 141         gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
 142 }
 143
 144 static int get_sda_gpio_value(struct i2c_adapter *adap)
 145 {
 146         return gpio_get_value(adap->bus_recovery_info->sda_gpio);
 147 }
 148
 149 static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap)
 150 {
 151         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
 152         struct device *dev = &adap->dev;
 153         int ret = 0;
 154
 155         ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
 156                         GPIOF_OUT_INIT_HIGH, "i2c-scl");
 157         if (ret) {
 158                 dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio);
 159                 return ret;
 160         }
 161
 162         if (bri->get_sda) {
 163                 if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) {
 164                         /* work without SDA polling */
 165                         dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA polling\n",
 166                                         bri->sda_gpio);
 167                         bri->get_sda = NULL;
 168                 }
 169         }
 170
 171         return ret;
 172 }
 173
 174 static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap)
 175 {
 176         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
 177
 178         if (bri->get_sda)
 179                 gpio_free(bri->sda_gpio);
 180
 181         gpio_free(bri->scl_gpio);
 182 }
 183
 184 /*
 185  * We are generating clock pulses. ndelay() determines durating of clk pulses.
 186  * We will generate clock with rate 100 KHz and so duration of both clock levels
 187  * is: delay in ns = (10^6 / 100) / 2
 188  */
 189 #define RECOVERY_NDELAY         5000
 190 #define RECOVERY_CLK_CNT        9
 191
 192 static int i2c_generic_recovery(struct i2c_adapter *adap)
 193 {
 194         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
 195         int i = 0, val = 1, ret = 0;
 196
 197         if (bri->prepare_recovery)
 198                 bri->prepare_recovery(adap);
 199
 200         bri->set_scl(adap, val);
 201         ndelay(RECOVERY_NDELAY);
 202
 203         /*
 204          * By this time SCL is high, as we need to give 9 falling-rising edges
 205          */
 206         while (i++ < RECOVERY_CLK_CNT * 2) {
 207                 if (val) {
 208                         /* Break if SDA is high */
 209                         if (bri->get_sda && bri->get_sda(adap))
 210                                         break;
 211                         /* SCL shouldn't be low here */
 212                         if (!bri->get_scl(adap)) {
 213                                 dev_err(&adap->dev,
 214                                         "SCL is stuck low, exit recovery\n");
 215                                 ret = -EBUSY;
 216                                 break;
 217                         }
 218                 }
 219
 220                 val = !val;
 221                 bri->set_scl(adap, val);
 222                 ndelay(RECOVERY_NDELAY);
 223         }
 224
 225         if (bri->unprepare_recovery)
 226                 bri->unprepare_recovery(adap);
 227
 228         return ret;
 229 }
 230
 231 int i2c_generic_scl_recovery(struct i2c_adapter *adap)
 232 {
 233         return i2c_generic_recovery(adap);
 234 }
 235 EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
 236
 237 int i2c_generic_gpio_recovery(struct i2c_adapter *adap)
 238 {
 239         int ret;
 240
 241         ret = i2c_get_gpios_for_recovery(adap);
 242         if (ret)
 243                 return ret;
 244
 245         ret = i2c_generic_recovery(adap);
 246         i2c_put_gpios_for_recovery(adap);
 247
 248         return ret;
 249 }
 250 EXPORT_SYMBOL_GPL(i2c_generic_gpio_recovery);
 251
 252 int i2c_recover_bus(struct i2c_adapter *adap)
 253 {
 254         if (!adap->bus_recovery_info)
 255                 return -EOPNOTSUPP;
 256
 257         dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
 258         return adap->bus_recovery_info->recover_bus(adap);
 259 }
 260 EXPORT_SYMBOL_GPL(i2c_recover_bus);
 261
 262 static void i2c_init_recovery(struct i2c_adapter *adap)
 263 {
 264         struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
 265         char *err_str;
 266
 267         if (!bri)
 268                 return;
 269
 270         if (!bri->recover_bus) {
 271                 err_str = "no recover_bus() found";
 272                 goto err;
 273         }
 274
 275         /* Generic GPIO recovery */
 276         if (bri->recover_bus == i2c_generic_gpio_recovery) {
 277                 if (!gpio_is_valid(bri->scl_gpio)) {
 278                         err_str = "invalid SCL gpio";
 279                         goto err;
 280                 }
 281
 282                 if (gpio_is_valid(bri->sda_gpio))
 283                         bri->get_sda = get_sda_gpio_value;
 284                 else
 285                         bri->get_sda = NULL;
 286
 287                 bri->get_scl = get_scl_gpio_value;
 288                 bri->set_scl = set_scl_gpio_value;
 289         } else if (bri->recover_bus == i2c_generic_scl_recovery) {
 290                 /* Generic SCL recovery */
 291                 if (!bri->set_scl || !bri->get_scl) {
 292                         err_str = "no {get|set}_scl() found";
 293                         goto err;
 294                 }
 295         }
 296
 297         return;
 298  err:
 299         dev_err(&adap->dev, "Not using recovery: %s\n", err_str);
 300         adap->bus_recovery_info = NULL;
 301 }
 302
 303 static int i2c_smbus_host_notify_to_irq(const struct i2c_client *client)
 304 {
 305         struct i2c_adapter *adap = client->adapter;
 306         unsigned int irq;
 307
 308         if (!adap->host_notify_domain)
 309                 return -ENXIO;
 310
 311         if (client->flags & I2C_CLIENT_TEN)
 312                 return -EINVAL;
 313
 314         irq = irq_find_mapping(adap->host_notify_domain, client->addr);
 315         if (!irq)
 316                 irq = irq_create_mapping(adap->host_notify_domain,
 317                                          client->addr);
 318
 319         return irq > 0 ? irq : -ENXIO;
 320 }
 321
 322 static int i2c_device_probe(struct device *dev)
 323 {
 324         struct i2c_client       *client = i2c_verify_client(dev);
 325         struct i2c_driver       *driver;
 326         int status;
 327
 328         if (!client)
 329                 return 0;
 330
 331         driver = to_i2c_driver(dev->driver);
 332
 333         if (!client->irq && !driver->disable_i2c_core_irq_mapping) {
 334                 int irq = -ENOENT;
 335
 336                 if (client->flags & I2C_CLIENT_HOST_NOTIFY) {
 337                         dev_dbg(dev, "Using Host Notify IRQ\n");
 338                         irq = i2c_smbus_host_notify_to_irq(client);
 339                 } else if (dev->of_node) {
 340                         irq = of_irq_get_byname(dev->of_node, "irq");
 341                         if (irq == -EINVAL || irq == -ENODATA)
 342                                 irq = of_irq_get(dev->of_node, 0);
 343                 } else if (ACPI_COMPANION(dev)) {
 344                         irq = acpi_dev_gpio_irq_get(ACPI_COMPANION(dev), 0);
 345                 }
 346                 if (irq == -EPROBE_DEFER)
 347                         return irq;
 348
 349                 if (irq < 0)
 350                         irq = 0;
 351
 352                 client->irq = irq;
 353         }
 354
 355         /*
 356          * An I2C ID table is not mandatory, if and only if, a suitable Device
 357          * Tree match table entry is supplied for the probing device.
 358          */
 359         if (!driver->id_table &&
 360             !i2c_acpi_match_device(dev->driver->acpi_match_table, client) &&
 361             !i2c_of_match_device(dev->driver->of_match_table, client))
 362                 return -ENODEV;
 363
 364         if (client->flags & I2C_CLIENT_WAKE) {
 365                 int wakeirq = -ENOENT;
 366
 367                 if (dev->of_node) {
 368                         wakeirq = of_irq_get_byname(dev->of_node, "wakeup");
 369                         if (wakeirq == -EPROBE_DEFER)
 370                                 return wakeirq;
 371                 }
 372
 373                 device_init_wakeup(&client->dev, true);
 374
 375                 if (wakeirq > 0 && wakeirq != client->irq)
 376                         status = dev_pm_set_dedicated_wake_irq(dev, wakeirq);
 377                 else if (client->irq > 0)
 378                         status = dev_pm_set_wake_irq(dev, client->irq);
 379                 else
 380                         status = 0;
 381
 382                 if (status)
 383                         dev_warn(&client->dev, "failed to set up wakeup irq\n");
 384         }
 385
 386         dev_dbg(dev, "probe\n");
 387
 388         status = of_clk_set_defaults(dev->of_node, false);
 389         if (status < 0)
 390                 goto err_clear_wakeup_irq;
 391
 392         status = dev_pm_domain_attach(&client->dev, true);
 393         if (status == -EPROBE_DEFER)
 394                 goto err_clear_wakeup_irq;
 395
 396         /*
 397          * When there are no more users of probe(),
 398          * rename probe_new to probe.
 399          */
 400         if (driver->probe_new)
 401                 status = driver->probe_new(client);
 402         else if (driver->probe)
 403                 status = driver->probe(client,
 404                                        i2c_match_id(driver->id_table, client));
 405         else
 406                 status = -EINVAL;
 407
 408         if (status)
 409                 goto err_detach_pm_domain;
 410
 411         return 0;
 412
 413 err_detach_pm_domain:
 414         dev_pm_domain_detach(&client->dev, true);
 415 err_clear_wakeup_irq:
 416         dev_pm_clear_wake_irq(&client->dev);
 417         device_init_wakeup(&client->dev, false);
 418         return status;
 419 }
 420
 421 static int i2c_device_remove(struct device *dev)
 422 {
 423         struct i2c_client       *client = i2c_verify_client(dev);
 424         struct i2c_driver       *driver;
 425         int status = 0;
 426
 427         if (!client || !dev->driver)
 428                 return 0;
 429
 430         driver = to_i2c_driver(dev->driver);
 431         if (driver->remove) {
 432                 dev_dbg(dev, "remove\n");
 433                 status = driver->remove(client);
 434         }
 435
 436         dev_pm_domain_detach(&client->dev, true);
 437
 438         dev_pm_clear_wake_irq(&client->dev);
 439         device_init_wakeup(&client->dev, false);
 440
 441         return status;
 442 }
 443
 444 static void i2c_device_shutdown(struct device *dev)
 445 {
 446         struct i2c_client *client = i2c_verify_client(dev);
 447         struct i2c_driver *driver;
 448
 449         if (!client || !dev->driver)
 450                 return;
 451         driver = to_i2c_driver(dev->driver);
 452         if (driver->shutdown)
 453                 driver->shutdown(client);
 454 }
 455
 456 static void i2c_client_dev_release(struct device *dev)
 457 {
 458         kfree(to_i2c_client(dev));
 459 }
 460
 461 static ssize_t
 462 show_name(struct device *dev, struct device_attribute *attr, char *buf)
 463 {
 464         return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
 465                        to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
 466 }
 467 static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 468
 469 static ssize_t
 470 show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
 471 {
 472         struct i2c_client *client = to_i2c_client(dev);
 473         int len;
 474
 475         len = acpi_device_modalias(dev, buf, PAGE_SIZE -1);
 476         if (len != -ENODEV)
 477                 return len;
 478
 479         return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
 480 }
 481 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
 482
 483 static struct attribute *i2c_dev_attrs[] = {
 484         &dev_attr_name.attr,
 485         /* modalias helps coldplug:  modprobe $(cat .../modalias) */
 486         &dev_attr_modalias.attr,
 487         NULL
 488 };
 489 ATTRIBUTE_GROUPS(i2c_dev);
 490
 491 struct bus_type i2c_bus_type = {
 492         .name           = "i2c",
 493         .match          = i2c_device_match,
 494         .probe          = i2c_device_probe,
 495         .remove         = i2c_device_remove,
 496         .shutdown       = i2c_device_shutdown,
 497 };
 498 EXPORT_SYMBOL_GPL(i2c_bus_type);
 499
 500 struct device_type i2c_client_type = {
 501         .groups         = i2c_dev_groups,
 502         .uevent         = i2c_device_uevent,
 503         .release        = i2c_client_dev_release,
 504 };
 505 EXPORT_SYMBOL_GPL(i2c_client_type);
 506
 507
 508 /**
 509  * i2c_verify_client - return parameter as i2c_client, or NULL
 510  * @dev: device, probably from some driver model iterator
 511  *
 512  * When traversing the driver model tree, perhaps using driver model
 513  * iterators like @device_for_each_child(), you can't assume very much
 514  * about the nodes you find.  Use this function to avoid oopses caused
 515  * by wrongly treating some non-I2C device as an i2c_client.
 516  */
 517 struct i2c_client *i2c_verify_client(struct device *dev)
 518 {
 519         return (dev->type == &i2c_client_type)
 520                         ? to_i2c_client(dev)
 521                         : NULL;
 522 }
 523 EXPORT_SYMBOL(i2c_verify_client);
 524
 525
 526 /* Return a unique address which takes the flags of the client into account */
 527 static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
 528 {
 529         unsigned short addr = client->addr;
 530
 531         /* For some client flags, add an arbitrary offset to avoid collisions */
 532         if (client->flags & I2C_CLIENT_TEN)
 533                 addr |= I2C_ADDR_OFFSET_TEN_BIT;
 534
 535         if (client->flags & I2C_CLIENT_SLAVE)
 536                 addr |= I2C_ADDR_OFFSET_SLAVE;
 537
 538         return addr;
 539 }
 540
 541 /* This is a permissive address validity check, I2C address map constraints
 542  * are purposely not enforced, except for the general call address. */
 543 int i2c_check_addr_validity(unsigned addr, unsigned short flags)
 544 {
 545         if (flags & I2C_CLIENT_TEN) {
 546                 /* 10-bit address, all values are valid */
 547                 if (addr > 0x3ff)
 548                         return -EINVAL;
 549         } else {
 550                 /* 7-bit address, reject the general call address */
 551                 if (addr == 0x00 || addr > 0x7f)
 552                         return -EINVAL;
 553         }
 554         return 0;
 555 }
 556
 557 /* And this is a strict address validity check, used when probing. If a
 558  * device uses a reserved address, then it shouldn't be probed. 7-bit
 559  * addressing is assumed, 10-bit address devices are rare and should be
 560  * explicitly enumerated. */
 561 int i2c_check_7bit_addr_validity_strict(unsigned short addr)
 562 {
 563         /*
 564          * Reserved addresses per I2C specification:
 565          *  0x00       General call address / START byte
 566          *  0x01       CBUS address
 567          *  0x02       Reserved for different bus format
 568          *  0x03       Reserved for future purposes
 569          *  0x04-0x07  Hs-mode master code
 570          *  0x78-0x7b  10-bit slave addressing
 571          *  0x7c-0x7f  Reserved for future purposes
 572          */
 573         if (addr < 0x08 || addr > 0x77)
 574                 return -EINVAL;
 575         return 0;
 576 }
 577
 578 static int __i2c_check_addr_busy(struct device *dev, void *addrp)
 579 {
 580         struct i2c_client       *client = i2c_verify_client(dev);
 581         int                     addr = *(int *)addrp;
 582
 583         if (client && i2c_encode_flags_to_addr(client) == addr)
 584                 return -EBUSY;
 585         return 0;
 586 }
 587
 588 /* walk up mux tree */
 589 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
 590 {
 591         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 592         int result;
 593
 594         result = device_for_each_child(&adapter->dev, &addr,
 595                                         __i2c_check_addr_busy);
 596
 597         if (!result && parent)
 598                 result = i2c_check_mux_parents(parent, addr);
 599
 600         return result;
 601 }
 602
 603 /* recurse down mux tree */
 604 static int i2c_check_mux_children(struct device *dev, void *addrp)
 605 {
 606         int result;
 607
 608         if (dev->type == &i2c_adapter_type)
 609                 result = device_for_each_child(dev, addrp,
 610                                                 i2c_check_mux_children);
 611         else
 612                 result = __i2c_check_addr_busy(dev, addrp);
 613
 614         return result;
 615 }
 616
 617 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
 618 {
 619         struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 620         int result = 0;
 621
 622         if (parent)
 623                 result = i2c_check_mux_parents(parent, addr);
 624
 625         if (!result)
 626                 result = device_for_each_child(&adapter->dev, &addr,
 627                                                 i2c_check_mux_children);
 628
 629         return result;
 630 }
 631
 632 /**
 633  * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
 634  * @adapter: Target I2C bus segment
 635  * @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
 636  *      locks only this branch in the adapter tree
 637  */
 638 static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
 639                                  unsigned int flags)
 640 {
 641         rt_mutex_lock(&adapter->bus_lock);
 642 }
 643
 644 /**
 645  * i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
 646  * @adapter: Target I2C bus segment
 647  * @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
 648  *      trylocks only this branch in the adapter tree
 649  */
 650 static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
 651                                    unsigned int flags)
 652 {
 653         return rt_mutex_trylock(&adapter->bus_lock);
 654 }
 655
 656 /**
 657  * i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
 658  * @adapter: Target I2C bus segment
 659  * @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
 660  *      unlocks only this branch in the adapter tree
 661  */
 662 static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
 663                                    unsigned int flags)
 664 {
 665         rt_mutex_unlock(&adapter->bus_lock);
 666 }
 667
 668 static void i2c_dev_set_name(struct i2c_adapter *adap,
 669                              struct i2c_client *client)
 670 {
 671         struct acpi_device *adev = ACPI_COMPANION(&client->dev);
 672
 673         if (adev) {
 674                 dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
 675                 return;
 676         }
 677
 678         dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
 679                      i2c_encode_flags_to_addr(client));
 680 }
 681
 682 static int i2c_dev_irq_from_resources(const struct resource *resources,
 683                                       unsigned int num_resources)
 684 {
 685         struct irq_data *irqd;
 686         int i;
 687
 688         for (i = 0; i < num_resources; i++) {
 689                 const struct resource *r = &resources[i];
 690
 691                 if (resource_type(r) != IORESOURCE_IRQ)
 692                         continue;
 693
 694                 if (r->flags & IORESOURCE_BITS) {
 695                         irqd = irq_get_irq_data(r->start);
 696                         if (!irqd)
 697                                 break;
 698
 699                         irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
 700                 }
 701
 702                 return r->start;
 703         }
 704
 705         return 0;
 706 }
 707
 708 /**
 709  * i2c_new_device - instantiate an i2c device
 710  * @adap: the adapter managing the device
 711  * @info: describes one I2C device; bus_num is ignored
 712  * Context: can sleep
 713  *
 714  * Create an i2c device. Binding is handled through driver model
 715  * probe()/remove() methods.  A driver may be bound to this device when we
 716  * return from this function, or any later moment (e.g. maybe hotplugging will
 717  * load the driver module).  This call is not appropriate for use by mainboard
 718  * initialization logic, which usually runs during an arch_initcall() long
 719  * before any i2c_adapter could exist.
 720  *
 721  * This returns the new i2c client, which may be saved for later use with
 722  * i2c_unregister_device(); or NULL to indicate an error.
 723  */
 724 struct i2c_client *
 725 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
 726 {
 727         struct i2c_client       *client;
 728         int                     status;
 729
 730         client = kzalloc(sizeof *client, GFP_KERNEL);
 731         if (!client)
 732                 return NULL;
 733
 734         client->adapter = adap;
 735
 736         client->dev.platform_data = info->platform_data;
 737
 738         if (info->archdata)
 739                 client->dev.archdata = *info->archdata;
 740
 741         client->flags = info->flags;
 742         client->addr = info->addr;
 743
 744         client->irq = info->irq;
 745         if (!client->irq)
 746                 client->irq = i2c_dev_irq_from_resources(info->resources,
 747                                                          info->num_resources);
 748
 749         strlcpy(client->name, info->type, sizeof(client->name));
 750
 751         status = i2c_check_addr_validity(client->addr, client->flags);
 752         if (status) {
 753                 dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
 754                         client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
 755                 goto out_err_silent;
 756         }
 757
 758         /* Check for address business */
 759         status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
 760         if (status)
 761                 goto out_err;
 762
 763         client->dev.parent = &client->adapter->dev;
 764         client->dev.bus = &i2c_bus_type;
 765         client->dev.type = &i2c_client_type;
 766         client->dev.of_node = info->of_node;
 767         client->dev.fwnode = info->fwnode;
 768
 769         i2c_dev_set_name(adap, client);
 770
 771         if (info->properties) {
 772                 status = device_add_properties(&client->dev, info->properties);
 773                 if (status) {
 774                         dev_err(&adap->dev,
 775                                 "Failed to add properties to client %s: %d\n",
 776                                 client->name, status);
 777                         goto out_err;
 778                 }
 779         }
 780
 781         status = device_register(&client->dev);
 782         if (status)
 783                 goto out_free_props;
 784
 785         dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
 786                 client->name, dev_name(&client->dev));
 787
 788         return client;
 789
 790 out_free_props:
 791         if (info->properties)
 792                 device_remove_properties(&client->dev);
 793 out_err:
 794         dev_err(&adap->dev,
 795                 "Failed to register i2c client %s at 0x%02x (%d)\n",
 796                 client->name, client->addr, status);
 797 out_err_silent:
 798         kfree(client);
 799         return NULL;
 800 }
 801 EXPORT_SYMBOL_GPL(i2c_new_device);
 802
 803
 804 /**
 805  * i2c_unregister_device - reverse effect of i2c_new_device()
 806  * @client: value returned from i2c_new_device()
 807  * Context: can sleep
 808  */
 809 void i2c_unregister_device(struct i2c_client *client)
 810 {
 811         if (client->dev.of_node)
 812                 of_node_clear_flag(client->dev.of_node, OF_POPULATED);
 813         if (ACPI_COMPANION(&client->dev))
 814                 acpi_device_clear_enumerated(ACPI_COMPANION(&client->dev));
 815         device_unregister(&client->dev);
 816 }
 817 EXPORT_SYMBOL_GPL(i2c_unregister_device);
 818
 819
 820 static const struct i2c_device_id dummy_id[] = {
 821         { "dummy", 0 },
 822         { },
 823 };
 824
 825 static int dummy_probe(struct i2c_client *client,
 826                        const struct i2c_device_id *id)
 827 {
 828         return 0;
 829 }
 830
 831 static int dummy_remove(struct i2c_client *client)
 832 {
 833         return 0;
 834 }
 835
 836 static struct i2c_driver dummy_driver = {
 837         .driver.name    = "dummy",
 838         .probe          = dummy_probe,
 839         .remove         = dummy_remove,
 840         .id_table       = dummy_id,
 841 };
 842
 843 /**
 844  * i2c_new_dummy - return a new i2c device bound to a dummy driver
 845  * @adapter: the adapter managing the device
 846  * @address: seven bit address to be used
 847  * Context: can sleep
 848  *
 849  * This returns an I2C client bound to the "dummy" driver, intended for use
 850  * with devices that consume multiple addresses.  Examples of such chips
 851  * include various EEPROMS (like 24c04 and 24c08 models).
 852  *
 853  * These dummy devices have two main uses.  First, most I2C and SMBus calls
 854  * except i2c_transfer() need a client handle; the dummy will be that handle.
 855  * And second, this prevents the specified address from being bound to a
 856  * different driver.
 857  *
 858  * This returns the new i2c client, which should be saved for later use with
 859  * i2c_unregister_device(); or NULL to indicate an error.
 860  */
 861 struct i2c_client *i2c_new_dummy(struct i2c_adapter *adapter, u16 address)
 862 {
 863         struct i2c_board_info info = {
 864                 I2C_BOARD_INFO("dummy", address),
 865         };
 866
 867         return i2c_new_device(adapter, &info);
 868 }
 869 EXPORT_SYMBOL_GPL(i2c_new_dummy);
 870
 871 /**
 872  * i2c_new_secondary_device - Helper to get the instantiated secondary address
 873  * and create the associated device
 874  * @client: Handle to the primary client
 875  * @name: Handle to specify which secondary address to get
 876  * @default_addr: Used as a fallback if no secondary address was specified
 877  * Context: can sleep
 878  *
 879  * I2C clients can be composed of multiple I2C slaves bound together in a single
 880  * component. The I2C client driver then binds to the master I2C slave and needs
 881  * to create I2C dummy clients to communicate with all the other slaves.
 882  *
 883  * This function creates and returns an I2C dummy client whose I2C address is
 884  * retrieved from the platform firmware based on the given slave name. If no
 885  * address is specified by the firmware default_addr is used.
 886  *
 887  * On DT-based platforms the address is retrieved from the "reg" property entry
 888  * cell whose "reg-names" value matches the slave name.
 889  *
 890  * This returns the new i2c client, which should be saved for later use with
 891  * i2c_unregister_device(); or NULL to indicate an error.
 892  */
 893 struct i2c_client *i2c_new_secondary_device(struct i2c_client *client,
 894                                                 const char *name,
 895                                                 u16 default_addr)
 896 {
 897         struct device_node *np = client->dev.of_node;
 898         u32 addr = default_addr;
 899         int i;
 900
 901         if (np) {
 902                 i = of_property_match_string(np, "reg-names", name);
 903                 if (i >= 0)
 904                         of_property_read_u32_index(np, "reg", i, &addr);
 905         }
 906
 907         dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
 908         return i2c_new_dummy(client->adapter, addr);
 909 }
 910 EXPORT_SYMBOL_GPL(i2c_new_secondary_device);
 911
 912 /* ------------------------------------------------------------------------- */
 913
 914 /* I2C bus adapters -- one roots each I2C or SMBUS segment */
 915
 916 static void i2c_adapter_dev_release(struct device *dev)
 917 {
 918         struct i2c_adapter *adap = to_i2c_adapter(dev);
 919         complete(&adap->dev_released);
 920 }
 921
 922 unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
 923 {
 924         unsigned int depth = 0;
 925
 926         while ((adapter = i2c_parent_is_i2c_adapter(adapter)))
 927                 depth++;
 928
 929         WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
 930                   "adapter depth exceeds lockdep subclass limit\n");
 931
 932         return depth;
 933 }
 934 EXPORT_SYMBOL_GPL(i2c_adapter_depth);
 935
 936 /*
 937  * Let users instantiate I2C devices through sysfs. This can be used when
 938  * platform initialization code doesn't contain the proper data for
 939  * whatever reason. Also useful for drivers that do device detection and
 940  * detection fails, either because the device uses an unexpected address,
 941  * or this is a compatible device with different ID register values.
 942  *
 943  * Parameter checking may look overzealous, but we really don't want
 944  * the user to provide incorrect parameters.
 945  */
 946 static ssize_t
 947 i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
 948                      const char *buf, size_t count)
 949 {
 950         struct i2c_adapter *adap = to_i2c_adapter(dev);
 951         struct i2c_board_info info;
 952         struct i2c_client *client;
 953         char *blank, end;
 954         int res;
 955
 956         memset(&info, 0, sizeof(struct i2c_board_info));
 957
 958         blank = strchr(buf, ' ');
 959         if (!blank) {
 960                 dev_err(dev, "%s: Missing parameters\n", "new_device");
 961                 return -EINVAL;
 962         }
 963         if (blank - buf > I2C_NAME_SIZE - 1) {
 964                 dev_err(dev, "%s: Invalid device name\n", "new_device");
 965                 return -EINVAL;
 966         }
 967         memcpy(info.type, buf, blank - buf);
 968
 969         /* Parse remaining parameters, reject extra parameters */
 970         res = sscanf(++blank, "%hi%c", &info.addr, &end);
 971         if (res < 1) {
 972                 dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
 973                 return -EINVAL;
 974         }
 975         if (res > 1  && end != '\n') {
 976                 dev_err(dev, "%s: Extra parameters\n", "new_device");
 977                 return -EINVAL;
 978         }
 979
 980         if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
 981                 info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
 982                 info.flags |= I2C_CLIENT_TEN;
 983         }
 984
 985         if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
 986                 info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
 987                 info.flags |= I2C_CLIENT_SLAVE;
 988         }
 989
 990         client = i2c_new_device(adap, &info);
 991         if (!client)
 992                 return -EINVAL;
 993
 994         /* Keep track of the added device */
 995         mutex_lock(&adap->userspace_clients_lock);
 996         list_add_tail(&client->detected, &adap->userspace_clients);
 997         mutex_unlock(&adap->userspace_clients_lock);
 998         dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
 999                  info.type, info.addr);
1000
1001         return count;
1002 }
1003 static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
1004
1005 /*
1006  * And of course let the users delete the devices they instantiated, if
1007  * they got it wrong. This interface can only be used to delete devices
1008  * instantiated by i2c_sysfs_new_device above. This guarantees that we
1009  * don't delete devices to which some kernel code still has references.
1010  *
1011  * Parameter checking may look overzealous, but we really don't want
1012  * the user to delete the wrong device.
1013  */
1014 static ssize_t
1015 i2c_sysfs_delete_device(struct device *dev, struct device_attribute *attr,
1016                         const char *buf, size_t count)
1017 {
1018         struct i2c_adapter *adap = to_i2c_adapter(dev);
1019         struct i2c_client *client, *next;
1020         unsigned short addr;
1021         char end;
1022         int res;
1023
1024         /* Parse parameters, reject extra parameters */
1025         res = sscanf(buf, "%hi%c", &addr, &end);
1026         if (res < 1) {
1027                 dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1028                 return -EINVAL;
1029         }
1030         if (res > 1  && end != '\n') {
1031                 dev_err(dev, "%s: Extra parameters\n", "delete_device");
1032                 return -EINVAL;
1033         }
1034
1035         /* Make sure the device was added through sysfs */
1036         res = -ENOENT;
1037         mutex_lock_nested(&adap->userspace_clients_lock,
1038                           i2c_adapter_depth(adap));
1039         list_for_each_entry_safe(client, next, &adap->userspace_clients,
1040                                  detected) {
1041                 if (i2c_encode_flags_to_addr(client) == addr) {
1042                         dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1043                                  "delete_device", client->name, client->addr);
1044
1045                         list_del(&client->detected);
1046                         i2c_unregister_device(client);
1047                         res = count;
1048                         break;
1049                 }
1050         }
1051         mutex_unlock(&adap->userspace_clients_lock);
1052
1053         if (res < 0)
1054                 dev_err(dev, "%s: Can't find device in list\n",
1055                         "delete_device");
1056         return res;
1057 }
1058 static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1059                                    i2c_sysfs_delete_device);
1060
1061 static struct attribute *i2c_adapter_attrs[] = {
1062         &dev_attr_name.attr,
1063         &dev_attr_new_device.attr,
1064         &dev_attr_delete_device.attr,
1065         NULL
1066 };
1067 ATTRIBUTE_GROUPS(i2c_adapter);
1068
1069 struct device_type i2c_adapter_type = {
1070         .groups         = i2c_adapter_groups,
1071         .release        = i2c_adapter_dev_release,
1072 };
1073 EXPORT_SYMBOL_GPL(i2c_adapter_type);
1074
1075 /**
1076  * i2c_verify_adapter - return parameter as i2c_adapter or NULL
1077  * @dev: device, probably from some driver model iterator
1078  *
1079  * When traversing the driver model tree, perhaps using driver model
1080  * iterators like @device_for_each_child(), you can't assume very much
1081  * about the nodes you find.  Use this function to avoid oopses caused
1082  * by wrongly treating some non-I2C device as an i2c_adapter.
1083  */
1084 struct i2c_adapter *i2c_verify_adapter(struct device *dev)
1085 {
1086         return (dev->type == &i2c_adapter_type)
1087                         ? to_i2c_adapter(dev)
1088                         : NULL;
1089 }
1090 EXPORT_SYMBOL(i2c_verify_adapter);
1091
1092 #ifdef CONFIG_I2C_COMPAT
1093 static struct class_compat *i2c_adapter_compat_class;
1094 #endif
1095
1096 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1097 {
1098         struct i2c_devinfo      *devinfo;
1099
1100         down_read(&__i2c_board_lock);
1101         list_for_each_entry(devinfo, &__i2c_board_list, list) {
1102                 if (devinfo->busnum == adapter->nr
1103                                 && !i2c_new_device(adapter,
1104                                                 &devinfo->board_info))
1105                         dev_err(&adapter->dev,
1106                                 "Can't create device at 0x%02x\n",
1107                                 devinfo->board_info.addr);
1108         }
1109         up_read(&__i2c_board_lock);
1110 }
1111
1112 static int i2c_do_add_adapter(struct i2c_driver *driver,
1113                               struct i2c_adapter *adap)
1114 {
1115         /* Detect supported devices on that bus, and instantiate them */
1116         i2c_detect(adap, driver);
1117
1118         /* Let legacy drivers scan this bus for matching devices */
1119         if (driver->attach_adapter) {
1120                 dev_warn(&adap->dev, "%s: attach_adapter method is deprecated\n",
1121                          driver->driver.name);
1122                 dev_warn(&adap->dev,
1123                          "Please use another way to instantiate your i2c_client\n");
1124                 /* We ignore the return code; if it fails, too bad */
1125                 driver->attach_adapter(adap);
1126         }
1127         return 0;
1128 }
1129
1130 static int __process_new_adapter(struct device_driver *d, void *data)
1131 {
1132         return i2c_do_add_adapter(to_i2c_driver(d), data);
1133 }
1134
1135 static const struct i2c_lock_operations i2c_adapter_lock_ops = {
1136         .lock_bus =    i2c_adapter_lock_bus,
1137         .trylock_bus = i2c_adapter_trylock_bus,
1138         .unlock_bus =  i2c_adapter_unlock_bus,
1139 };
1140
1141 static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
1142 {
1143         struct irq_domain *domain = adap->host_notify_domain;
1144         irq_hw_number_t hwirq;
1145
1146         if (!domain)
1147                 return;
1148
1149         for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
1150                 irq_dispose_mapping(irq_find_mapping(domain, hwirq));
1151
1152         irq_domain_remove(domain);
1153         adap->host_notify_domain = NULL;
1154 }
1155
1156 static int i2c_host_notify_irq_map(struct irq_domain *h,
1157                                           unsigned int virq,
1158                                           irq_hw_number_t hw_irq_num)
1159 {
1160         irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
1161
1162         return 0;
1163 }
1164
1165 static const struct irq_domain_ops i2c_host_notify_irq_ops = {
1166         .map = i2c_host_notify_irq_map,
1167 };
1168
1169 static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
1170 {
1171         struct irq_domain *domain;
1172
1173         if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
1174                 return 0;
1175
1176         domain = irq_domain_create_linear(adap->dev.fwnode,
1177                                           I2C_ADDR_7BITS_COUNT,
1178                                           &i2c_host_notify_irq_ops, adap);
1179         if (!domain)
1180                 return -ENOMEM;
1181
1182         adap->host_notify_domain = domain;
1183
1184         return 0;
1185 }
1186
1187 /**
1188  * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
1189  * I2C client.
1190  * @adap: the adapter
1191  * @addr: the I2C address of the notifying device
1192  * Context: can't sleep
1193  *
1194  * Helper function to be called from an I2C bus driver's interrupt
1195  * handler. It will schedule the Host Notify IRQ.
1196  */
1197 int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
1198 {
1199         int irq;
1200
1201         if (!adap)
1202                 return -EINVAL;
1203
1204         irq = irq_find_mapping(adap->host_notify_domain, addr);
1205         if (irq <= 0)
1206                 return -ENXIO;
1207
1208         generic_handle_irq(irq);
1209
1210         return 0;
1211 }
1212 EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
1213
1214 static int i2c_register_adapter(struct i2c_adapter *adap)
1215 {
1216         int res = -EINVAL;
1217
1218         /* Can't register until after driver model init */
1219         if (WARN_ON(!is_registered)) {
1220                 res = -EAGAIN;
1221                 goto out_list;
1222         }
1223
1224         /* Sanity checks */
1225         if (WARN(!adap->name[0], "i2c adapter has no name"))
1226                 goto out_list;
1227
1228         if (!adap->algo) {
1229                 pr_err("adapter '%s': no algo supplied!\n", adap->name);
1230                 goto out_list;
1231         }
1232
1233         if (!adap->lock_ops)
1234                 adap->lock_ops = &i2c_adapter_lock_ops;
1235
1236         rt_mutex_init(&adap->bus_lock);
1237         rt_mutex_init(&adap->mux_lock);
1238         mutex_init(&adap->userspace_clients_lock);
1239         INIT_LIST_HEAD(&adap->userspace_clients);
1240
1241         /* Set default timeout to 1 second if not already set */
1242         if (adap->timeout == 0)
1243                 adap->timeout = HZ;
1244
1245         /* register soft irqs for Host Notify */
1246         res = i2c_setup_host_notify_irq_domain(adap);
1247         if (res) {
1248                 pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
1249                        adap->name, res);
1250                 goto out_list;
1251         }
1252
1253         dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1254         adap->dev.bus = &i2c_bus_type;
1255         adap->dev.type = &i2c_adapter_type;
1256         res = device_register(&adap->dev);
1257         if (res) {
1258                 pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
1259                 goto out_list;
1260         }
1261
1262         dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1263
1264         pm_runtime_no_callbacks(&adap->dev);
1265         pm_suspend_ignore_children(&adap->dev, true);
1266         pm_runtime_enable(&adap->dev);
1267
1268 #ifdef CONFIG_I2C_COMPAT
1269         res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
1270                                        adap->dev.parent);
1271         if (res)
1272                 dev_warn(&adap->dev,
1273                          "Failed to create compatibility class link\n");
1274 #endif
1275
1276         i2c_init_recovery(adap);
1277
1278         /* create pre-declared device nodes */
1279         of_i2c_register_devices(adap);
1280         i2c_acpi_register_devices(adap);
1281         i2c_acpi_install_space_handler(adap);
1282
1283         if (adap->nr < __i2c_first_dynamic_bus_num)
1284                 i2c_scan_static_board_info(adap);
1285
1286         /* Notify drivers */
1287         mutex_lock(&core_lock);
1288         bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1289         mutex_unlock(&core_lock);
1290
1291         return 0;
1292
1293 out_list:
1294         mutex_lock(&core_lock);
1295         idr_remove(&i2c_adapter_idr, adap->nr);
1296         mutex_unlock(&core_lock);
1297         return res;
1298 }
1299
1300 /**
1301  * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1302  * @adap: the adapter to register (with adap->nr initialized)
1303  * Context: can sleep
1304  *
1305  * See i2c_add_numbered_adapter() for details.
1306  */
1307 static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1308 {
1309         int id;
1310
1311         mutex_lock(&core_lock);
1312         id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL);
1313         mutex_unlock(&core_lock);
1314         if (WARN(id < 0, "couldn't get idr"))
1315                 return id == -ENOSPC ? -EBUSY : id;
1316
1317         return i2c_register_adapter(adap);
1318 }
1319
1320 /**
1321  * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1322  * @adapter: the adapter to add
1323  * Context: can sleep
1324  *
1325  * This routine is used to declare an I2C adapter when its bus number
1326  * doesn't matter or when its bus number is specified by an dt alias.
1327  * Examples of bases when the bus number doesn't matter: I2C adapters
1328  * dynamically added by USB links or PCI plugin cards.
1329  *
1330  * When this returns zero, a new bus number was allocated and stored
1331  * in adap->nr, and the specified adapter became available for clients.
1332  * Otherwise, a negative errno value is returned.
1333  */
1334 int i2c_add_adapter(struct i2c_adapter *adapter)
1335 {
1336         struct device *dev = &adapter->dev;
1337         int id;
1338
1339         if (dev->of_node) {
1340                 id = of_alias_get_id(dev->of_node, "i2c");
1341                 if (id >= 0) {
1342                         adapter->nr = id;
1343                         return __i2c_add_numbered_adapter(adapter);
1344                 }
1345         }
1346
1347         mutex_lock(&core_lock);
1348         id = idr_alloc(&i2c_adapter_idr, adapter,
1349                        __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1350         mutex_unlock(&core_lock);
1351         if (WARN(id < 0, "couldn't get idr"))
1352                 return id;
1353
1354         adapter->nr = id;
1355
1356         return i2c_register_adapter(adapter);
1357 }
1358 EXPORT_SYMBOL(i2c_add_adapter);
1359
1360 /**
1361  * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1362  * @adap: the adapter to register (with adap->nr initialized)
1363  * Context: can sleep
1364  *
1365  * This routine is used to declare an I2C adapter when its bus number
1366  * matters.  For example, use it for I2C adapters from system-on-chip CPUs,
1367  * or otherwise built in to the system's mainboard, and where i2c_board_info
1368  * is used to properly configure I2C devices.
1369  *
1370  * If the requested bus number is set to -1, then this function will behave
1371  * identically to i2c_add_adapter, and will dynamically assign a bus number.
1372  *
1373  * If no devices have pre-been declared for this bus, then be sure to
1374  * register the adapter before any dynamically allocated ones.  Otherwise
1375  * the required bus ID may not be available.
1376  *
1377  * When this returns zero, the specified adapter became available for
1378  * clients using the bus number provided in adap->nr.  Also, the table
1379  * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1380  * and the appropriate driver model device nodes are created.  Otherwise, a
1381  * negative errno value is returned.
1382  */
1383 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1384 {
1385         if (adap->nr == -1) /* -1 means dynamically assign bus id */
1386                 return i2c_add_adapter(adap);
1387
1388         return __i2c_add_numbered_adapter(adap);
1389 }
1390 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1391
1392 static void i2c_do_del_adapter(struct i2c_driver *driver,
1393                               struct i2c_adapter *adapter)
1394 {
1395         struct i2c_client *client, *_n;
1396
1397         /* Remove the devices we created ourselves as the result of hardware
1398          * probing (using a driver's detect method) */
1399         list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1400                 if (client->adapter == adapter) {
1401                         dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1402                                 client->name, client->addr);
1403                         list_del(&client->detected);
1404                         i2c_unregister_device(client);
1405                 }
1406         }
1407 }
1408
1409 static int __unregister_client(struct device *dev, void *dummy)
1410 {
1411         struct i2c_client *client = i2c_verify_client(dev);
1412         if (client && strcmp(client->name, "dummy"))
1413                 i2c_unregister_device(client);
1414         return 0;
1415 }
1416
1417 static int __unregister_dummy(struct device *dev, void *dummy)
1418 {
1419         struct i2c_client *client = i2c_verify_client(dev);
1420         if (client)
1421                 i2c_unregister_device(client);
1422         return 0;
1423 }
1424
1425 static int __process_removed_adapter(struct device_driver *d, void *data)
1426 {
1427         i2c_do_del_adapter(to_i2c_driver(d), data);
1428         return 0;
1429 }
1430
1431 /**
1432  * i2c_del_adapter - unregister I2C adapter
1433  * @adap: the adapter being unregistered
1434  * Context: can sleep
1435  *
1436  * This unregisters an I2C adapter which was previously registered
1437  * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1438  */
1439 void i2c_del_adapter(struct i2c_adapter *adap)
1440 {
1441         struct i2c_adapter *found;
1442         struct i2c_client *client, *next;
1443
1444         /* First make sure that this adapter was ever added */
1445         mutex_lock(&core_lock);
1446         found = idr_find(&i2c_adapter_idr, adap->nr);
1447         mutex_unlock(&core_lock);
1448         if (found != adap) {
1449                 pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
1450                 return;
1451         }
1452
1453         i2c_acpi_remove_space_handler(adap);
1454         /* Tell drivers about this removal */
1455         mutex_lock(&core_lock);
1456         bus_for_each_drv(&i2c_bus_type, NULL, adap,
1457                                __process_removed_adapter);
1458         mutex_unlock(&core_lock);
1459
1460         /* Remove devices instantiated from sysfs */
1461         mutex_lock_nested(&adap->userspace_clients_lock,
1462                           i2c_adapter_depth(adap));
1463         list_for_each_entry_safe(client, next, &adap->userspace_clients,
1464                                  detected) {
1465                 dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1466                         client->addr);
1467                 list_del(&client->detected);
1468                 i2c_unregister_device(client);
1469         }
1470         mutex_unlock(&adap->userspace_clients_lock);
1471
1472         /* Detach any active clients. This can't fail, thus we do not
1473          * check the returned value. This is a two-pass process, because
1474          * we can't remove the dummy devices during the first pass: they
1475          * could have been instantiated by real devices wishing to clean
1476          * them up properly, so we give them a chance to do that first. */
1477         device_for_each_child(&adap->dev, NULL, __unregister_client);
1478         device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1479
1480 #ifdef CONFIG_I2C_COMPAT
1481         class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
1482                                  adap->dev.parent);
1483 #endif
1484
1485         /* device name is gone after device_unregister */
1486         dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1487
1488         pm_runtime_disable(&adap->dev);
1489
1490         i2c_host_notify_irq_teardown(adap);
1491
1492         /* wait until all references to the device are gone
1493          *
1494          * FIXME: This is old code and should ideally be replaced by an
1495          * alternative which results in decoupling the lifetime of the struct
1496          * device from the i2c_adapter, like spi or netdev do. Any solution
1497          * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1498          */
1499         init_completion(&adap->dev_released);
1500         device_unregister(&adap->dev);
1501         wait_for_completion(&adap->dev_released);
1502
1503         /* free bus id */
1504         mutex_lock(&core_lock);
1505         idr_remove(&i2c_adapter_idr, adap->nr);
1506         mutex_unlock(&core_lock);
1507
1508         /* Clear the device structure in case this adapter is ever going to be
1509            added again */
1510         memset(&adap->dev, 0, sizeof(adap->dev));
1511 }
1512 EXPORT_SYMBOL(i2c_del_adapter);
1513
1514 /**
1515  * i2c_parse_fw_timings - get I2C related timing parameters from firmware
1516  * @dev: The device to scan for I2C timing properties
1517  * @t: the i2c_timings struct to be filled with values
1518  * @use_defaults: bool to use sane defaults derived from the I2C specification
1519  *                when properties are not found, otherwise use 0
1520  *
1521  * Scan the device for the generic I2C properties describing timing parameters
1522  * for the signal and fill the given struct with the results. If a property was
1523  * not found and use_defaults was true, then maximum timings are assumed which
1524  * are derived from the I2C specification. If use_defaults is not used, the
1525  * results will be 0, so drivers can apply their own defaults later. The latter
1526  * is mainly intended for avoiding regressions of existing drivers which want
1527  * to switch to this function. New drivers almost always should use the defaults.
1528  */
1529
1530 void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults)
1531 {
1532         int ret;
1533
1534         memset(t, 0, sizeof(*t));
1535
1536         ret = device_property_read_u32(dev, "clock-frequency", &t->bus_freq_hz);
1537         if (ret && use_defaults)
1538                 t->bus_freq_hz = 100000;
1539
1540         ret = device_property_read_u32(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns);
1541         if (ret && use_defaults) {
1542                 if (t->bus_freq_hz <= 100000)
1543                         t->scl_rise_ns = 1000;
1544                 else if (t->bus_freq_hz <= 400000)
1545                         t->scl_rise_ns = 300;
1546                 else
1547                         t->scl_rise_ns = 120;
1548         }
1549
1550         ret = device_property_read_u32(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns);
1551         if (ret && use_defaults) {
1552                 if (t->bus_freq_hz <= 400000)
1553                         t->scl_fall_ns = 300;
1554                 else
1555                         t->scl_fall_ns = 120;
1556         }
1557
1558         device_property_read_u32(dev, "i2c-scl-internal-delay-ns", &t->scl_int_delay_ns);
1559
1560         ret = device_property_read_u32(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns);
1561         if (ret && use_defaults)
1562                 t->sda_fall_ns = t->scl_fall_ns;
1563 }
1564 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1565
1566 /* ------------------------------------------------------------------------- */
1567
1568 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *))
1569 {
1570         int res;
1571
1572         mutex_lock(&core_lock);
1573         res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1574         mutex_unlock(&core_lock);
1575
1576         return res;
1577 }
1578 EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1579
1580 static int __process_new_driver(struct device *dev, void *data)
1581 {
1582         if (dev->type != &i2c_adapter_type)
1583                 return 0;
1584         return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1585 }
1586
1587 /*
1588  * An i2c_driver is used with one or more i2c_client (device) nodes to access
1589  * i2c slave chips, on a bus instance associated with some i2c_adapter.
1590  */
1591
1592 int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
1593 {
1594         int res;
1595
1596         /* Can't register until after driver model init */
1597         if (WARN_ON(!is_registered))
1598                 return -EAGAIN;
1599
1600         /* add the driver to the list of i2c drivers in the driver core */
1601         driver->driver.owner = owner;
1602         driver->driver.bus = &i2c_bus_type;
1603         INIT_LIST_HEAD(&driver->clients);
1604
1605         /* When registration returns, the driver core
1606          * will have called probe() for all matching-but-unbound devices.
1607          */
1608         res = driver_register(&driver->driver);
1609         if (res)
1610                 return res;
1611
1612         pr_debug("driver [%s] registered\n", driver->driver.name);
1613
1614         /* Walk the adapters that are already present */
1615         i2c_for_each_dev(driver, __process_new_driver);
1616
1617         return 0;
1618 }
1619 EXPORT_SYMBOL(i2c_register_driver);
1620
1621 static int __process_removed_driver(struct device *dev, void *data)
1622 {
1623         if (dev->type == &i2c_adapter_type)
1624                 i2c_do_del_adapter(data, to_i2c_adapter(dev));
1625         return 0;
1626 }
1627
1628 /**
1629  * i2c_del_driver - unregister I2C driver
1630  * @driver: the driver being unregistered
1631  * Context: can sleep
1632  */
1633 void i2c_del_driver(struct i2c_driver *driver)
1634 {
1635         i2c_for_each_dev(driver, __process_removed_driver);
1636
1637         driver_unregister(&driver->driver);
1638         pr_debug("driver [%s] unregistered\n", driver->driver.name);
1639 }
1640 EXPORT_SYMBOL(i2c_del_driver);
1641
1642 /* ------------------------------------------------------------------------- */
1643
1644 /**
1645  * i2c_use_client - increments the reference count of the i2c client structure
1646  * @client: the client being referenced
1647  *
1648  * Each live reference to a client should be refcounted. The driver model does
1649  * that automatically as part of driver binding, so that most drivers don't
1650  * need to do this explicitly: they hold a reference until they're unbound
1651  * from the device.
1652  *
1653  * A pointer to the client with the incremented reference counter is returned.
1654  */
1655 struct i2c_client *i2c_use_client(struct i2c_client *client)
1656 {
1657         if (client && get_device(&client->dev))
1658                 return client;
1659         return NULL;
1660 }
1661 EXPORT_SYMBOL(i2c_use_client);
1662
1663 /**
1664  * i2c_release_client - release a use of the i2c client structure
1665  * @client: the client being no longer referenced
1666  *
1667  * Must be called when a user of a client is finished with it.
1668  */
1669 void i2c_release_client(struct i2c_client *client)
1670 {
1671         if (client)
1672                 put_device(&client->dev);
1673 }
1674 EXPORT_SYMBOL(i2c_release_client);
1675
1676 struct i2c_cmd_arg {
1677         unsigned        cmd;
1678         void            *arg;
1679 };
1680
1681 static int i2c_cmd(struct device *dev, void *_arg)
1682 {
1683         struct i2c_client       *client = i2c_verify_client(dev);
1684         struct i2c_cmd_arg      *arg = _arg;
1685         struct i2c_driver       *driver;
1686
1687         if (!client || !client->dev.driver)
1688                 return 0;
1689
1690         driver = to_i2c_driver(client->dev.driver);
1691         if (driver->command)
1692                 driver->command(client, arg->cmd, arg->arg);
1693         return 0;
1694 }
1695
1696 void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
1697 {
1698         struct i2c_cmd_arg      cmd_arg;
1699
1700         cmd_arg.cmd = cmd;
1701         cmd_arg.arg = arg;
1702         device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
1703 }
1704 EXPORT_SYMBOL(i2c_clients_command);
1705
1706 static int __init i2c_init(void)
1707 {
1708         int retval;
1709
1710         retval = of_alias_get_highest_id("i2c");
1711
1712         down_write(&__i2c_board_lock);
1713         if (retval >= __i2c_first_dynamic_bus_num)
1714                 __i2c_first_dynamic_bus_num = retval + 1;
1715         up_write(&__i2c_board_lock);
1716
1717         retval = bus_register(&i2c_bus_type);
1718         if (retval)
1719                 return retval;
1720
1721         is_registered = true;
1722
1723 #ifdef CONFIG_I2C_COMPAT
1724         i2c_adapter_compat_class = class_compat_register("i2c-adapter");
1725         if (!i2c_adapter_compat_class) {
1726                 retval = -ENOMEM;
1727                 goto bus_err;
1728         }
1729 #endif
1730         retval = i2c_add_driver(&dummy_driver);
1731         if (retval)
1732                 goto class_err;
1733
1734         if (IS_ENABLED(CONFIG_OF_DYNAMIC))
1735                 WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
1736         if (IS_ENABLED(CONFIG_ACPI))
1737                 WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
1738
1739         return 0;
1740
1741 class_err:
1742 #ifdef CONFIG_I2C_COMPAT
1743         class_compat_unregister(i2c_adapter_compat_class);
1744 bus_err:
1745 #endif
1746         is_registered = false;
1747         bus_unregister(&i2c_bus_type);
1748         return retval;
1749 }
1750
1751 static void __exit i2c_exit(void)
1752 {
1753         if (IS_ENABLED(CONFIG_ACPI))
1754                 WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
1755         if (IS_ENABLED(CONFIG_OF_DYNAMIC))
1756                 WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
1757         i2c_del_driver(&dummy_driver);
1758 #ifdef CONFIG_I2C_COMPAT
1759         class_compat_unregister(i2c_adapter_compat_class);
1760 #endif
1761         bus_unregister(&i2c_bus_type);
1762         tracepoint_synchronize_unregister();
1763 }
1764
1765 /* We must initialize early, because some subsystems register i2c drivers
1766  * in subsys_initcall() code, but are linked (and initialized) before i2c.
1767  */
1768 postcore_initcall(i2c_init);
1769 module_exit(i2c_exit);
1770
1771 /* ----------------------------------------------------
1772  * the functional interface to the i2c busses.
1773  * ----------------------------------------------------
1774  */
1775
1776 /* Check if val is exceeding the quirk IFF quirk is non 0 */
1777 #define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
1778
1779 static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
1780 {
1781         dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
1782                             err_msg, msg->addr, msg->len,
1783                             msg->flags & I2C_M_RD ? "read" : "write");
1784         return -EOPNOTSUPP;
1785 }
1786
1787 static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1788 {
1789         const struct i2c_adapter_quirks *q = adap->quirks;
1790         int max_num = q->max_num_msgs, i;
1791         bool do_len_check = true;
1792
1793         if (q->flags & I2C_AQ_COMB) {
1794                 max_num = 2;
1795
1796                 /* special checks for combined messages */
1797                 if (num == 2) {
1798                         if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
1799                                 return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
1800
1801                         if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
1802                                 return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
1803
1804                         if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
1805                                 return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
1806
1807                         if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
1808                                 return i2c_quirk_error(adap, &msgs[0], "msg too long");
1809
1810                         if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
1811                                 return i2c_quirk_error(adap, &msgs[1], "msg too long");
1812
1813                         do_len_check = false;
1814                 }
1815         }
1816
1817         if (i2c_quirk_exceeded(num, max_num))
1818                 return i2c_quirk_error(adap, &msgs[0], "too many messages");
1819
1820         for (i = 0; i < num; i++) {
1821                 u16 len = msgs[i].len;
1822
1823                 if (msgs[i].flags & I2C_M_RD) {
1824                         if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
1825                                 return i2c_quirk_error(adap, &msgs[i], "msg too long");
1826                 } else {
1827                         if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
1828                                 return i2c_quirk_error(adap, &msgs[i], "msg too long");
1829                 }
1830         }
1831
1832         return 0;
1833 }
1834
1835 /**
1836  * __i2c_transfer - unlocked flavor of i2c_transfer
1837  * @adap: Handle to I2C bus
1838  * @msgs: One or more messages to execute before STOP is issued to
1839  *      terminate the operation; each message begins with a START.
1840  * @num: Number of messages to be executed.
1841  *
1842  * Returns negative errno, else the number of messages executed.
1843  *
1844  * Adapter lock must be held when calling this function. No debug logging
1845  * takes place. adap->algo->master_xfer existence isn't checked.
1846  */
1847 int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1848 {
1849         unsigned long orig_jiffies;
1850         int ret, try;
1851
1852         if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
1853                 return -EOPNOTSUPP;
1854
1855         /* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
1856          * enabled.  This is an efficient way of keeping the for-loop from
1857          * being executed when not needed.
1858          */
1859         if (static_key_false(&i2c_trace_msg)) {
1860                 int i;
1861                 for (i = 0; i < num; i++)
1862                         if (msgs[i].flags & I2C_M_RD)
1863                                 trace_i2c_read(adap, &msgs[i], i);
1864                         else
1865                                 trace_i2c_write(adap, &msgs[i], i);
1866         }
1867
1868         /* Retry automatically on arbitration loss */
1869         orig_jiffies = jiffies;
1870         for (ret = 0, try = 0; try <= adap->retries; try++) {
1871                 ret = adap->algo->master_xfer(adap, msgs, num);
1872                 if (ret != -EAGAIN)
1873                         break;
1874                 if (time_after(jiffies, orig_jiffies + adap->timeout))
1875                         break;
1876         }
1877
1878         if (static_key_false(&i2c_trace_msg)) {
1879                 int i;
1880                 for (i = 0; i < ret; i++)
1881                         if (msgs[i].flags & I2C_M_RD)
1882                                 trace_i2c_reply(adap, &msgs[i], i);
1883                 trace_i2c_result(adap, i, ret);
1884         }
1885
1886         return ret;
1887 }
1888 EXPORT_SYMBOL(__i2c_transfer);
1889
1890 /**
1891  * i2c_transfer - execute a single or combined I2C message
1892  * @adap: Handle to I2C bus
1893  * @msgs: One or more messages to execute before STOP is issued to
1894  *      terminate the operation; each message begins with a START.
1895  * @num: Number of messages to be executed.
1896  *
1897  * Returns negative errno, else the number of messages executed.
1898  *
1899  * Note that there is no requirement that each message be sent to
1900  * the same slave address, although that is the most common model.
1901  */
1902 int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
1903 {
1904         int ret;
1905
1906         /* REVISIT the fault reporting model here is weak:
1907          *
1908          *  - When we get an error after receiving N bytes from a slave,
1909          *    there is no way to report "N".
1910          *
1911          *  - When we get a NAK after transmitting N bytes to a slave,
1912          *    there is no way to report "N" ... or to let the master
1913          *    continue executing the rest of this combined message, if
1914          *    that's the appropriate response.
1915          *
1916          *  - When for example "num" is two and we successfully complete
1917          *    the first message but get an error part way through the
1918          *    second, it's unclear whether that should be reported as
1919          *    one (discarding status on the second message) or errno
1920          *    (discarding status on the first one).
1921          */
1922
1923         if (adap->algo->master_xfer) {
1924 #ifdef DEBUG
1925                 for (ret = 0; ret < num; ret++) {
1926                         dev_dbg(&adap->dev,
1927                                 "master_xfer[%d] %c, addr=0x%02x, len=%d%s\n",
1928                                 ret, (msgs[ret].flags & I2C_M_RD) ? 'R' : 'W',
1929                                 msgs[ret].addr, msgs[ret].len,
1930                                 (msgs[ret].flags & I2C_M_RECV_LEN) ? "+" : "");
1931                 }
1932 #endif
1933
1934                 if (in_atomic() || irqs_disabled()) {
1935                         ret = i2c_trylock_bus(adap, I2C_LOCK_SEGMENT);
1936                         if (!ret)
1937                                 /* I2C activity is ongoing. */
1938                                 return -EAGAIN;
1939                 } else {
1940                         i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
1941                 }
1942
1943                 ret = __i2c_transfer(adap, msgs, num);
1944                 i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
1945
1946                 return ret;
1947         } else {
1948                 dev_dbg(&adap->dev, "I2C level transfers not supported\n");
1949                 return -EOPNOTSUPP;
1950         }
1951 }
1952 EXPORT_SYMBOL(i2c_transfer);
1953
1954 /**
1955  * i2c_master_send - issue a single I2C message in master transmit mode
1956  * @client: Handle to slave device
1957  * @buf: Data that will be written to the slave
1958  * @count: How many bytes to write, must be less than 64k since msg.len is u16
1959  *
1960  * Returns negative errno, or else the number of bytes written.
1961  */
1962 int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
1963 {
1964         int ret;
1965         struct i2c_adapter *adap = client->adapter;
1966         struct i2c_msg msg;
1967
1968         msg.addr = client->addr;
1969         msg.flags = client->flags & I2C_M_TEN;
1970         msg.len = count;
1971         msg.buf = (char *)buf;
1972
1973         ret = i2c_transfer(adap, &msg, 1);
1974
1975         /*
1976          * If everything went ok (i.e. 1 msg transmitted), return #bytes
1977          * transmitted, else error code.
1978          */
1979         return (ret == 1) ? count : ret;
1980 }
1981 EXPORT_SYMBOL(i2c_master_send);
1982
1983 /**
1984  * i2c_master_recv - issue a single I2C message in master receive mode
1985  * @client: Handle to slave device
1986  * @buf: Where to store data read from slave
1987  * @count: How many bytes to read, must be less than 64k since msg.len is u16
1988  *
1989  * Returns negative errno, or else the number of bytes read.
1990  */
1991 int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
1992 {
1993         struct i2c_adapter *adap = client->adapter;
1994         struct i2c_msg msg;
1995         int ret;
1996
1997         msg.addr = client->addr;
1998         msg.flags = client->flags & I2C_M_TEN;
1999         msg.flags |= I2C_M_RD;
2000         msg.len = count;
2001         msg.buf = buf;
2002
2003         ret = i2c_transfer(adap, &msg, 1);
2004
2005         /*
2006          * If everything went ok (i.e. 1 msg received), return #bytes received,
2007          * else error code.
2008          */
2009         return (ret == 1) ? count : ret;
2010 }
2011 EXPORT_SYMBOL(i2c_master_recv);
2012
2013 /* ----------------------------------------------------
2014  * the i2c address scanning function
2015  * Will not work for 10-bit addresses!
2016  * ----------------------------------------------------
2017  */
2018
2019 /*
2020  * Legacy default probe function, mostly relevant for SMBus. The default
2021  * probe method is a quick write, but it is known to corrupt the 24RF08
2022  * EEPROMs due to a state machine bug, and could also irreversibly
2023  * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2024  * we use a short byte read instead. Also, some bus drivers don't implement
2025  * quick write, so we fallback to a byte read in that case too.
2026  * On x86, there is another special case for FSC hardware monitoring chips,
2027  * which want regular byte reads (address 0x73.) Fortunately, these are the
2028  * only known chips using this I2C address on PC hardware.
2029  * Returns 1 if probe succeeded, 0 if not.
2030  */
2031 static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
2032 {
2033         int err;
2034         union i2c_smbus_data dummy;
2035
2036 #ifdef CONFIG_X86
2037         if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
2038          && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2039                 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2040                                      I2C_SMBUS_BYTE_DATA, &dummy);
2041         else
2042 #endif
2043         if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
2044          && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2045                 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
2046                                      I2C_SMBUS_QUICK, NULL);
2047         else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2048                 err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2049                                      I2C_SMBUS_BYTE, &dummy);
2050         else {
2051                 dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2052                          addr);
2053                 err = -EOPNOTSUPP;
2054         }
2055
2056         return err >= 0;
2057 }
2058
2059 static int i2c_detect_address(struct i2c_client *temp_client,
2060                               struct i2c_driver *driver)
2061 {
2062         struct i2c_board_info info;
2063         struct i2c_adapter *adapter = temp_client->adapter;
2064         int addr = temp_client->addr;
2065         int err;
2066
2067         /* Make sure the address is valid */
2068         err = i2c_check_7bit_addr_validity_strict(addr);
2069         if (err) {
2070                 dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2071                          addr);
2072                 return err;
2073         }
2074
2075         /* Skip if already in use (7 bit, no need to encode flags) */
2076         if (i2c_check_addr_busy(adapter, addr))
2077                 return 0;
2078
2079         /* Make sure there is something at this address */
2080         if (!i2c_default_probe(adapter, addr))
2081                 return 0;
2082
2083         /* Finally call the custom detection function */
2084         memset(&info, 0, sizeof(struct i2c_board_info));
2085         info.addr = addr;
2086         err = driver->detect(temp_client, &info);
2087         if (err) {
2088                 /* -ENODEV is returned if the detection fails. We catch it
2089                    here as this isn't an error. */
2090                 return err == -ENODEV ? 0 : err;
2091         }
2092
2093         /* Consistency check */
2094         if (info.type[0] == '\0') {
2095                 dev_err(&adapter->dev,
2096                         "%s detection function provided no name for 0x%x\n",
2097                         driver->driver.name, addr);
2098         } else {
2099                 struct i2c_client *client;
2100
2101                 /* Detection succeeded, instantiate the device */
2102                 if (adapter->class & I2C_CLASS_DEPRECATED)
2103                         dev_warn(&adapter->dev,
2104                                 "This adapter will soon drop class based instantiation of devices. "
2105                                 "Please make sure client 0x%02x gets instantiated by other means. "
2106                                 "Check 'Documentation/i2c/instantiating-devices' for details.\n",
2107                                 info.addr);
2108
2109                 dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2110                         info.type, info.addr);
2111                 client = i2c_new_device(adapter, &info);
2112                 if (client)
2113                         list_add_tail(&client->detected, &driver->clients);
2114                 else
2115                         dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2116                                 info.type, info.addr);
2117         }
2118         return 0;
2119 }
2120
2121 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
2122 {
2123         const unsigned short *address_list;
2124         struct i2c_client *temp_client;
2125         int i, err = 0;
2126         int adap_id = i2c_adapter_id(adapter);
2127
2128         address_list = driver->address_list;
2129         if (!driver->detect || !address_list)
2130                 return 0;
2131
2132         /* Warn that the adapter lost class based instantiation */
2133         if (adapter->class == I2C_CLASS_DEPRECATED) {
2134                 dev_dbg(&adapter->dev,
2135                         "This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
2136                         "If you need it, check 'Documentation/i2c/instantiating-devices' for alternatives.\n",
2137                         driver->driver.name);
2138                 return 0;
2139         }
2140
2141         /* Stop here if the classes do not match */
2142         if (!(adapter->class & driver->class))
2143                 return 0;
2144
2145         /* Set up a temporary client to help detect callback */
2146         temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
2147         if (!temp_client)
2148                 return -ENOMEM;
2149         temp_client->adapter = adapter;
2150
2151         for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
2152                 dev_dbg(&adapter->dev,
2153                         "found normal entry for adapter %d, addr 0x%02x\n",
2154                         adap_id, address_list[i]);
2155                 temp_client->addr = address_list[i];
2156                 err = i2c_detect_address(temp_client, driver);
2157                 if (unlikely(err))
2158                         break;
2159         }
2160
2161         kfree(temp_client);
2162         return err;
2163 }
2164
2165 int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
2166 {
2167         return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2168                               I2C_SMBUS_QUICK, NULL) >= 0;
2169 }
2170 EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2171
2172 struct i2c_client *
2173 i2c_new_probed_device(struct i2c_adapter *adap,
2174                       struct i2c_board_info *info,
2175                       unsigned short const *addr_list,
2176                       int (*probe)(struct i2c_adapter *, unsigned short addr))
2177 {
2178         int i;
2179
2180         if (!probe)
2181                 probe = i2c_default_probe;
2182
2183         for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
2184                 /* Check address validity */
2185                 if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) {
2186                         dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
2187                                  addr_list[i]);
2188                         continue;
2189                 }
2190
2191                 /* Check address availability (7 bit, no need to encode flags) */
2192                 if (i2c_check_addr_busy(adap, addr_list[i])) {
2193                         dev_dbg(&adap->dev,
2194                                 "Address 0x%02x already in use, not probing\n",
2195                                 addr_list[i]);
2196                         continue;
2197                 }
2198
2199                 /* Test address responsiveness */
2200                 if (probe(adap, addr_list[i]))
2201                         break;
2202         }
2203
2204         if (addr_list[i] == I2C_CLIENT_END) {
2205                 dev_dbg(&adap->dev, "Probing failed, no device found\n");
2206                 return NULL;
2207         }
2208
2209         info->addr = addr_list[i];
2210         return i2c_new_device(adap, info);
2211 }
2212 EXPORT_SYMBOL_GPL(i2c_new_probed_device);
2213
2214 struct i2c_adapter *i2c_get_adapter(int nr)
2215 {
2216         struct i2c_adapter *adapter;
2217
2218         mutex_lock(&core_lock);
2219         adapter = idr_find(&i2c_adapter_idr, nr);
2220         if (!adapter)
2221                 goto exit;
2222
2223         if (try_module_get(adapter->owner))
2224                 get_device(&adapter->dev);
2225         else
2226                 adapter = NULL;
2227
2228  exit:
2229         mutex_unlock(&core_lock);
2230         return adapter;
2231 }
2232 EXPORT_SYMBOL(i2c_get_adapter);
2233
2234 void i2c_put_adapter(struct i2c_adapter *adap)
2235 {
2236         if (!adap)
2237                 return;
2238
2239         put_device(&adap->dev);
2240         module_put(adap->owner);
2241 }
2242 EXPORT_SYMBOL(i2c_put_adapter);
2243
2244 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2245 MODULE_DESCRIPTION("I2C-Bus main module");
2246 MODULE_LICENSE("GPL");