i2c-core-base.c

   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 */
  63static DEFINE_MUTEX(core_lock);
  64static DEFINE_IDR(i2c_adapter_idr);
  65
  66static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
  67
  68static DEFINE_STATIC_KEY_FALSE(i2c_trace_msg_key);
  69static bool is_registered;
  70
  71static struct dentry *i2c_debugfs_root;
  72
  73int i2c_transfer_trace_reg(void)
  74{
  75	static_branch_inc(&i2c_trace_msg_key);
  76	return 0;
  77}
  78
  79void i2c_transfer_trace_unreg(void)
  80{
  81	static_branch_dec(&i2c_trace_msg_key);
  82}
  83
  84const 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}
 103EXPORT_SYMBOL_GPL(i2c_freq_mode_string);
 104
 105const 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}
 118EXPORT_SYMBOL_GPL(i2c_match_id);
 119
 120const 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}
 137EXPORT_SYMBOL(i2c_get_match_data);
 138
 139static 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
 162static 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 */
 179static int get_scl_gpio_value(struct i2c_adapter *adap)
 180{
 181	return gpiod_get_value_cansleep(adap->bus_recovery_info->scl_gpiod);
 182}
 183
 184static 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
 189static int get_sda_gpio_value(struct i2c_adapter *adap)
 190{
 191	return gpiod_get_value_cansleep(adap->bus_recovery_info->sda_gpiod);
 192}
 193
 194static 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
 199static 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
 223int 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}
 292EXPORT_SYMBOL_GPL(i2c_generic_scl_recovery);
 293
 294int 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}
 302EXPORT_SYMBOL_GPL(i2c_recover_bus);
 303
 304static 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
 351static 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
 411cleanup_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
 419static 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
 425static 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
 475static 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
 491static 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, PD_FLAG_DETACH_POWER_OFF |
 577				      (do_power_on ? PD_FLAG_ATTACH_POWER_ON : 0));
 578	if (status)
 579		goto err_clear_wakeup_irq;
 580
 581	client->devres_group_id = devres_open_group(&client->dev, NULL,
 582						    GFP_KERNEL);
 583	if (!client->devres_group_id) {
 584		status = -ENOMEM;
 585		goto err_clear_wakeup_irq;
 586	}
 587
 588	client->debugfs = debugfs_create_dir(dev_name(&client->dev),
 589					     client->adapter->debugfs);
 590
 591	if (driver->probe)
 592		status = driver->probe(client);
 593	else
 594		status = -EINVAL;
 595
 596	/*
 597	 * Note that we are not closing the devres group opened above so
 598	 * even resources that were attached to the device after probe is
 599	 * run are released when i2c_device_remove() is executed. This is
 600	 * needed as some drivers would allocate additional resources,
 601	 * for example when updating firmware.
 602	 */
 603
 604	if (status)
 605		goto err_release_driver_resources;
 606
 607	return 0;
 608
 609err_release_driver_resources:
 610	debugfs_remove_recursive(client->debugfs);
 611	devres_release_group(&client->dev, client->devres_group_id);
 612err_clear_wakeup_irq:
 613	dev_pm_clear_wake_irq(&client->dev);
 614	device_init_wakeup(&client->dev, false);
 615put_sync_adapter:
 616	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
 617		pm_runtime_put_sync(&client->adapter->dev);
 618
 619	return status;
 620}
 621
 622static void i2c_device_remove(struct device *dev)
 623{
 624	struct i2c_client	*client = to_i2c_client(dev);
 625	struct i2c_driver	*driver;
 626
 627	driver = to_i2c_driver(dev->driver);
 628	if (driver->remove) {
 629		dev_dbg(dev, "remove\n");
 630
 631		driver->remove(client);
 632	}
 633
 634	debugfs_remove_recursive(client->debugfs);
 635
 636	devres_release_group(&client->dev, client->devres_group_id);
 637
 638	dev_pm_clear_wake_irq(&client->dev);
 639	device_init_wakeup(&client->dev, false);
 640
 641	client->irq = 0;
 642	if (client->flags & I2C_CLIENT_HOST_NOTIFY)
 643		pm_runtime_put(&client->adapter->dev);
 644}
 645
 646static void i2c_device_shutdown(struct device *dev)
 647{
 648	struct i2c_client *client = i2c_verify_client(dev);
 649	struct i2c_driver *driver;
 650
 651	if (!client || !dev->driver)
 652		return;
 653	driver = to_i2c_driver(dev->driver);
 654	if (driver->shutdown)
 655		driver->shutdown(client);
 656	else if (client->irq > 0)
 657		disable_irq(client->irq);
 658}
 659
 660static void i2c_client_dev_release(struct device *dev)
 661{
 662	kfree(to_i2c_client(dev));
 663}
 664
 665static ssize_t
 666name_show(struct device *dev, struct device_attribute *attr, char *buf)
 667{
 668	return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
 669		       to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
 670}
 671static DEVICE_ATTR_RO(name);
 672
 673static ssize_t
 674modalias_show(struct device *dev, struct device_attribute *attr, char *buf)
 675{
 676	struct i2c_client *client = to_i2c_client(dev);
 677	int len;
 678
 679	len = of_device_modalias(dev, buf, PAGE_SIZE);
 680	if (len != -ENODEV)
 681		return len;
 682
 683	len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
 684	if (len != -ENODEV)
 685		return len;
 686
 687	return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
 688}
 689static DEVICE_ATTR_RO(modalias);
 690
 691static struct attribute *i2c_dev_attrs[] = {
 692	&dev_attr_name.attr,
 693	/* modalias helps coldplug:  modprobe $(cat .../modalias) */
 694	&dev_attr_modalias.attr,
 695	NULL
 696};
 697ATTRIBUTE_GROUPS(i2c_dev);
 698
 699const struct bus_type i2c_bus_type = {
 700	.name		= "i2c",
 701	.match		= i2c_device_match,
 702	.probe		= i2c_device_probe,
 703	.remove		= i2c_device_remove,
 704	.shutdown	= i2c_device_shutdown,
 705};
 706EXPORT_SYMBOL_GPL(i2c_bus_type);
 707
 708const struct device_type i2c_client_type = {
 709	.groups		= i2c_dev_groups,
 710	.uevent		= i2c_device_uevent,
 711	.release	= i2c_client_dev_release,
 712};
 713EXPORT_SYMBOL_GPL(i2c_client_type);
 714
 715
 716/**
 717 * i2c_verify_client - return parameter as i2c_client, or NULL
 718 * @dev: device, probably from some driver model iterator
 719 *
 720 * When traversing the driver model tree, perhaps using driver model
 721 * iterators like @device_for_each_child(), you can't assume very much
 722 * about the nodes you find.  Use this function to avoid oopses caused
 723 * by wrongly treating some non-I2C device as an i2c_client.
 724 */
 725struct i2c_client *i2c_verify_client(struct device *dev)
 726{
 727	return (dev->type == &i2c_client_type)
 728			? to_i2c_client(dev)
 729			: NULL;
 730}
 731EXPORT_SYMBOL(i2c_verify_client);
 732
 733
 734/* Return a unique address which takes the flags of the client into account */
 735static unsigned short i2c_encode_flags_to_addr(struct i2c_client *client)
 736{
 737	unsigned short addr = client->addr;
 738
 739	/* For some client flags, add an arbitrary offset to avoid collisions */
 740	if (client->flags & I2C_CLIENT_TEN)
 741		addr |= I2C_ADDR_OFFSET_TEN_BIT;
 742
 743	if (client->flags & I2C_CLIENT_SLAVE)
 744		addr |= I2C_ADDR_OFFSET_SLAVE;
 745
 746	return addr;
 747}
 748
 749/* This is a permissive address validity check, I2C address map constraints
 750 * are purposely not enforced, except for the general call address. */
 751static int i2c_check_addr_validity(unsigned int addr, unsigned short flags)
 752{
 753	if (flags & I2C_CLIENT_TEN) {
 754		/* 10-bit address, all values are valid */
 755		if (addr > 0x3ff)
 756			return -EINVAL;
 757	} else {
 758		/* 7-bit address, reject the general call address */
 759		if (addr == 0x00 || addr > 0x7f)
 760			return -EINVAL;
 761	}
 762	return 0;
 763}
 764
 765/* And this is a strict address validity check, used when probing. If a
 766 * device uses a reserved address, then it shouldn't be probed. 7-bit
 767 * addressing is assumed, 10-bit address devices are rare and should be
 768 * explicitly enumerated. */
 769int i2c_check_7bit_addr_validity_strict(unsigned short addr)
 770{
 771	/*
 772	 * Reserved addresses per I2C specification:
 773	 *  0x00       General call address / START byte
 774	 *  0x01       CBUS address
 775	 *  0x02       Reserved for different bus format
 776	 *  0x03       Reserved for future purposes
 777	 *  0x04-0x07  Hs-mode master code
 778	 *  0x78-0x7b  10-bit slave addressing
 779	 *  0x7c-0x7f  Reserved for future purposes
 780	 */
 781	if (addr < 0x08 || addr > 0x77)
 782		return -EINVAL;
 783	return 0;
 784}
 785
 786static int __i2c_check_addr_busy(struct device *dev, void *addrp)
 787{
 788	struct i2c_client	*client = i2c_verify_client(dev);
 789	int			addr = *(int *)addrp;
 790
 791	if (client && i2c_encode_flags_to_addr(client) == addr)
 792		return -EBUSY;
 793	return 0;
 794}
 795
 796/* walk up mux tree */
 797static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
 798{
 799	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 800	int result;
 801
 802	result = device_for_each_child(&adapter->dev, &addr,
 803					__i2c_check_addr_busy);
 804
 805	if (!result && parent)
 806		result = i2c_check_mux_parents(parent, addr);
 807
 808	return result;
 809}
 810
 811/* recurse down mux tree */
 812static int i2c_check_mux_children(struct device *dev, void *addrp)
 813{
 814	int result;
 815
 816	if (dev->type == &i2c_adapter_type)
 817		result = device_for_each_child(dev, addrp,
 818						i2c_check_mux_children);
 819	else
 820		result = __i2c_check_addr_busy(dev, addrp);
 821
 822	return result;
 823}
 824
 825static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
 826{
 827	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 828	int result = 0;
 829
 830	if (parent)
 831		result = i2c_check_mux_parents(parent, addr);
 832
 833	if (!result)
 834		result = device_for_each_child(&adapter->dev, &addr,
 835						i2c_check_mux_children);
 836
 837	return result;
 838}
 839
 840/**
 841 * i2c_adapter_lock_bus - Get exclusive access to an I2C bus segment
 842 * @adapter: Target I2C bus segment
 843 * @flags: I2C_LOCK_ROOT_ADAPTER locks the root i2c adapter, I2C_LOCK_SEGMENT
 844 *	locks only this branch in the adapter tree
 845 */
 846static void i2c_adapter_lock_bus(struct i2c_adapter *adapter,
 847				 unsigned int flags)
 848{
 849	rt_mutex_lock_nested(&adapter->bus_lock, i2c_adapter_depth(adapter));
 850}
 851
 852/**
 853 * i2c_adapter_trylock_bus - Try to get exclusive access to an I2C bus segment
 854 * @adapter: Target I2C bus segment
 855 * @flags: I2C_LOCK_ROOT_ADAPTER trylocks the root i2c adapter, I2C_LOCK_SEGMENT
 856 *	trylocks only this branch in the adapter tree
 857 */
 858static int i2c_adapter_trylock_bus(struct i2c_adapter *adapter,
 859				   unsigned int flags)
 860{
 861	return rt_mutex_trylock(&adapter->bus_lock);
 862}
 863
 864/**
 865 * i2c_adapter_unlock_bus - Release exclusive access to an I2C bus segment
 866 * @adapter: Target I2C bus segment
 867 * @flags: I2C_LOCK_ROOT_ADAPTER unlocks the root i2c adapter, I2C_LOCK_SEGMENT
 868 *	unlocks only this branch in the adapter tree
 869 */
 870static void i2c_adapter_unlock_bus(struct i2c_adapter *adapter,
 871				   unsigned int flags)
 872{
 873	rt_mutex_unlock(&adapter->bus_lock);
 874}
 875
 876static void i2c_dev_set_name(struct i2c_adapter *adap,
 877			     struct i2c_client *client,
 878			     struct i2c_board_info const *info)
 879{
 880	struct acpi_device *adev = ACPI_COMPANION(&client->dev);
 881
 882	if (info && info->dev_name) {
 883		dev_set_name(&client->dev, "i2c-%s", info->dev_name);
 884		return;
 885	}
 886
 887	if (adev) {
 888		dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
 889		return;
 890	}
 891
 892	dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
 893		     i2c_encode_flags_to_addr(client));
 894}
 895
 896int i2c_dev_irq_from_resources(const struct resource *resources,
 897			       unsigned int num_resources)
 898{
 899	struct irq_data *irqd;
 900	int i;
 901
 902	for (i = 0; i < num_resources; i++) {
 903		const struct resource *r = &resources[i];
 904
 905		if (resource_type(r) != IORESOURCE_IRQ)
 906			continue;
 907
 908		if (r->flags & IORESOURCE_BITS) {
 909			irqd = irq_get_irq_data(r->start);
 910			if (!irqd)
 911				break;
 912
 913			irqd_set_trigger_type(irqd, r->flags & IORESOURCE_BITS);
 914		}
 915
 916		return r->start;
 917	}
 918
 919	return 0;
 920}
 921
 922/*
 923 * Serialize device instantiation in case it can be instantiated explicitly
 924 * and by auto-detection
 925 */
 926static int i2c_lock_addr(struct i2c_adapter *adap, unsigned short addr,
 927			 unsigned short flags)
 928{
 929	if (!(flags & I2C_CLIENT_TEN) &&
 930	    test_and_set_bit(addr, adap->addrs_in_instantiation))
 931		return -EBUSY;
 932
 933	return 0;
 934}
 935
 936static void i2c_unlock_addr(struct i2c_adapter *adap, unsigned short addr,
 937			    unsigned short flags)
 938{
 939	if (!(flags & I2C_CLIENT_TEN))
 940		clear_bit(addr, adap->addrs_in_instantiation);
 941}
 942
 943/**
 944 * i2c_new_client_device - instantiate an i2c device
 945 * @adap: the adapter managing the device
 946 * @info: describes one I2C device; bus_num is ignored
 947 * Context: can sleep
 948 *
 949 * Create an i2c device. Binding is handled through driver model
 950 * probe()/remove() methods.  A driver may be bound to this device when we
 951 * return from this function, or any later moment (e.g. maybe hotplugging will
 952 * load the driver module).  This call is not appropriate for use by mainboard
 953 * initialization logic, which usually runs during an arch_initcall() long
 954 * before any i2c_adapter could exist.
 955 *
 956 * This returns the new i2c client, which may be saved for later use with
 957 * i2c_unregister_device(); or an ERR_PTR to describe the error.
 958 */
 959struct i2c_client *
 960i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
 961{
 962	struct fwnode_handle *fwnode = info->fwnode;
 963	struct i2c_client *client;
 964	bool need_put = false;
 965	int status;
 966
 967	client = kzalloc(sizeof *client, GFP_KERNEL);
 968	if (!client)
 969		return ERR_PTR(-ENOMEM);
 970
 971	client->adapter = adap;
 972
 973	client->dev.platform_data = info->platform_data;
 974	client->flags = info->flags;
 975	client->addr = info->addr;
 976
 977	client->init_irq = info->irq;
 978	if (!client->init_irq)
 979		client->init_irq = i2c_dev_irq_from_resources(info->resources,
 980							 info->num_resources);
 981
 982	strscpy(client->name, info->type, sizeof(client->name));
 983
 984	status = i2c_check_addr_validity(client->addr, client->flags);
 985	if (status) {
 986		dev_err(&adap->dev, "Invalid %d-bit I2C address 0x%02hx\n",
 987			client->flags & I2C_CLIENT_TEN ? 10 : 7, client->addr);
 988		goto out_err_silent;
 989	}
 990
 991	status = i2c_lock_addr(adap, client->addr, client->flags);
 992	if (status)
 993		goto out_err_silent;
 994
 995	/* Check for address business */
 996	status = i2c_check_addr_busy(adap, i2c_encode_flags_to_addr(client));
 997	if (status)
 998		goto out_err;
 999
1000	client->dev.parent = &client->adapter->dev;
1001	client->dev.bus = &i2c_bus_type;
1002	client->dev.type = &i2c_client_type;
1003
1004	device_enable_async_suspend(&client->dev);
1005
1006	device_set_node(&client->dev, fwnode_handle_get(fwnode));
1007
1008	if (info->swnode) {
1009		status = device_add_software_node(&client->dev, info->swnode);
1010		if (status) {
1011			dev_err(&adap->dev,
1012				"Failed to add software node to client %s: %d\n",
1013				client->name, status);
1014			goto out_err_put_fwnode;
1015		}
1016	}
1017
1018	i2c_dev_set_name(adap, client, info);
1019	status = device_register(&client->dev);
1020	if (status)
1021		goto out_remove_swnode;
1022
1023	dev_dbg(&adap->dev, "client [%s] registered with bus id %s\n",
1024		client->name, dev_name(&client->dev));
1025
1026	i2c_unlock_addr(adap, client->addr, client->flags);
1027
1028	return client;
1029
1030out_remove_swnode:
1031	device_remove_software_node(&client->dev);
1032	need_put = true;
1033out_err_put_fwnode:
1034	fwnode_handle_put(fwnode);
1035out_err:
1036	dev_err(&adap->dev,
1037		"Failed to register i2c client %s at 0x%02x (%d)\n",
1038		client->name, client->addr, status);
1039	i2c_unlock_addr(adap, client->addr, client->flags);
1040out_err_silent:
1041	if (need_put)
1042		put_device(&client->dev);
1043	else
1044		kfree(client);
1045	return ERR_PTR(status);
1046}
1047EXPORT_SYMBOL_GPL(i2c_new_client_device);
1048
1049/**
1050 * i2c_unregister_device - reverse effect of i2c_new_*_device()
1051 * @client: value returned from i2c_new_*_device()
1052 * Context: can sleep
1053 */
1054void i2c_unregister_device(struct i2c_client *client)
1055{
1056	struct fwnode_handle *fwnode;
1057
1058	if (IS_ERR_OR_NULL(client))
1059		return;
1060
1061	fwnode = dev_fwnode(&client->dev);
1062	if (is_of_node(fwnode))
1063		of_node_clear_flag(to_of_node(fwnode), OF_POPULATED);
1064	else if (is_acpi_device_node(fwnode))
1065		acpi_device_clear_enumerated(to_acpi_device_node(fwnode));
1066
1067	/*
1068	 * If the primary fwnode is a software node it is free-ed by
1069	 * device_remove_software_node() below, avoid double-free.
1070	 */
1071	if (!is_software_node(fwnode))
1072		fwnode_handle_put(fwnode);
1073
1074	device_remove_software_node(&client->dev);
1075	device_unregister(&client->dev);
1076}
1077EXPORT_SYMBOL_GPL(i2c_unregister_device);
1078
1079/**
1080 * i2c_find_device_by_fwnode() - find an i2c_client for the fwnode
1081 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_client
1082 *
1083 * Look up and return the &struct i2c_client corresponding to the @fwnode.
1084 * If no client can be found, or @fwnode is NULL, this returns NULL.
1085 *
1086 * The user must call put_device(&client->dev) once done with the i2c client.
1087 */
1088struct i2c_client *i2c_find_device_by_fwnode(struct fwnode_handle *fwnode)
1089{
1090	struct i2c_client *client;
1091	struct device *dev;
1092
1093	if (!fwnode)
1094		return NULL;
1095
1096	dev = bus_find_device_by_fwnode(&i2c_bus_type, fwnode);
1097	if (!dev)
1098		return NULL;
1099
1100	client = i2c_verify_client(dev);
1101	if (!client)
1102		put_device(dev);
1103
1104	return client;
1105}
1106EXPORT_SYMBOL(i2c_find_device_by_fwnode);
1107
1108
1109static const struct i2c_device_id dummy_id[] = {
1110	{ "dummy", },
1111	{ "smbus_host_notify", },
1112	{ }
1113};
1114
1115static int dummy_probe(struct i2c_client *client)
1116{
1117	return 0;
1118}
1119
1120static struct i2c_driver dummy_driver = {
1121	.driver.name	= "dummy",
1122	.probe		= dummy_probe,
1123	.id_table	= dummy_id,
1124};
1125
1126/**
1127 * i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1128 * @adapter: the adapter managing the device
1129 * @address: seven bit address to be used
1130 * Context: can sleep
1131 *
1132 * This returns an I2C client bound to the "dummy" driver, intended for use
1133 * with devices that consume multiple addresses.  Examples of such chips
1134 * include various EEPROMS (like 24c04 and 24c08 models).
1135 *
1136 * These dummy devices have two main uses.  First, most I2C and SMBus calls
1137 * except i2c_transfer() need a client handle; the dummy will be that handle.
1138 * And second, this prevents the specified address from being bound to a
1139 * different driver.
1140 *
1141 * This returns the new i2c client, which should be saved for later use with
1142 * i2c_unregister_device(); or an ERR_PTR to describe the error.
1143 */
1144struct i2c_client *i2c_new_dummy_device(struct i2c_adapter *adapter, u16 address)
1145{
1146	struct i2c_board_info info = {
1147		I2C_BOARD_INFO("dummy", address),
1148	};
1149
1150	return i2c_new_client_device(adapter, &info);
1151}
1152EXPORT_SYMBOL_GPL(i2c_new_dummy_device);
1153
1154static void devm_i2c_release_dummy(void *client)
1155{
1156	i2c_unregister_device(client);
1157}
1158
1159/**
1160 * devm_i2c_new_dummy_device - return a new i2c device bound to a dummy driver
1161 * @dev: device the managed resource is bound to
1162 * @adapter: the adapter managing the device
1163 * @address: seven bit address to be used
1164 * Context: can sleep
1165 *
1166 * This is the device-managed version of @i2c_new_dummy_device. It returns the
1167 * new i2c client or an ERR_PTR in case of an error.
1168 */
1169struct i2c_client *devm_i2c_new_dummy_device(struct device *dev,
1170					     struct i2c_adapter *adapter,
1171					     u16 address)
1172{
1173	struct i2c_client *client;
1174	int ret;
1175
1176	client = i2c_new_dummy_device(adapter, address);
1177	if (IS_ERR(client))
1178		return client;
1179
1180	ret = devm_add_action_or_reset(dev, devm_i2c_release_dummy, client);
1181	if (ret)
1182		return ERR_PTR(ret);
1183
1184	return client;
1185}
1186EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
1187
1188/**
1189 * i2c_new_ancillary_device - Helper to get the instantiated secondary address
1190 * and create the associated device
1191 * @client: Handle to the primary client
1192 * @name: Handle to specify which secondary address to get
1193 * @default_addr: Used as a fallback if no secondary address was specified
1194 * Context: can sleep
1195 *
1196 * I2C clients can be composed of multiple I2C slaves bound together in a single
1197 * component. The I2C client driver then binds to the master I2C slave and needs
1198 * to create I2C dummy clients to communicate with all the other slaves.
1199 *
1200 * This function creates and returns an I2C dummy client whose I2C address is
1201 * retrieved from the platform firmware based on the given slave name. If no
1202 * address is specified by the firmware default_addr is used.
1203 *
1204 * On DT-based platforms the address is retrieved from the "reg" property entry
1205 * cell whose "reg-names" value matches the slave name.
1206 *
1207 * This returns the new i2c client, which should be saved for later use with
1208 * i2c_unregister_device(); or an ERR_PTR to describe the error.
1209 */
1210struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client,
1211						const char *name,
1212						u16 default_addr)
1213{
1214	struct device_node *np = client->dev.of_node;
1215	u32 addr = default_addr;
1216	int i;
1217
1218	i = of_property_match_string(np, "reg-names", name);
1219	if (i >= 0)
1220		of_property_read_u32_index(np, "reg", i, &addr);
1221
1222	dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
1223	return i2c_new_dummy_device(client->adapter, addr);
1224}
1225EXPORT_SYMBOL_GPL(i2c_new_ancillary_device);
1226
1227/* ------------------------------------------------------------------------- */
1228
1229/* I2C bus adapters -- one roots each I2C or SMBUS segment */
1230
1231static void i2c_adapter_dev_release(struct device *dev)
1232{
1233	struct i2c_adapter *adap = to_i2c_adapter(dev);
1234	complete(&adap->dev_released);
1235}
1236
1237unsigned int i2c_adapter_depth(struct i2c_adapter *adapter)
1238{
1239	unsigned int depth = 0;
1240	struct device *parent;
1241
1242	for (parent = adapter->dev.parent; parent; parent = parent->parent)
1243		if (parent->type == &i2c_adapter_type)
1244			depth++;
1245
1246	WARN_ONCE(depth >= MAX_LOCKDEP_SUBCLASSES,
1247		  "adapter depth exceeds lockdep subclass limit\n");
1248
1249	return depth;
1250}
1251EXPORT_SYMBOL_GPL(i2c_adapter_depth);
1252
1253/*
1254 * Let users instantiate I2C devices through sysfs. This can be used when
1255 * platform initialization code doesn't contain the proper data for
1256 * whatever reason. Also useful for drivers that do device detection and
1257 * detection fails, either because the device uses an unexpected address,
1258 * or this is a compatible device with different ID register values.
1259 *
1260 * Parameter checking may look overzealous, but we really don't want
1261 * the user to provide incorrect parameters.
1262 */
1263static ssize_t
1264new_device_store(struct device *dev, struct device_attribute *attr,
1265		 const char *buf, size_t count)
1266{
1267	struct i2c_adapter *adap = to_i2c_adapter(dev);
1268	struct i2c_board_info info;
1269	struct i2c_client *client;
1270	char *blank, end;
1271	int res;
1272
1273	memset(&info, 0, sizeof(struct i2c_board_info));
1274
1275	blank = strchr(buf, ' ');
1276	if (!blank) {
1277		dev_err(dev, "%s: Missing parameters\n", "new_device");
1278		return -EINVAL;
1279	}
1280	if (blank - buf > I2C_NAME_SIZE - 1) {
1281		dev_err(dev, "%s: Invalid device name\n", "new_device");
1282		return -EINVAL;
1283	}
1284	memcpy(info.type, buf, blank - buf);
1285
1286	/* Parse remaining parameters, reject extra parameters */
1287	res = sscanf(++blank, "%hi%c", &info.addr, &end);
1288	if (res < 1) {
1289		dev_err(dev, "%s: Can't parse I2C address\n", "new_device");
1290		return -EINVAL;
1291	}
1292	if (res > 1  && end != '\n') {
1293		dev_err(dev, "%s: Extra parameters\n", "new_device");
1294		return -EINVAL;
1295	}
1296
1297	if ((info.addr & I2C_ADDR_OFFSET_TEN_BIT) == I2C_ADDR_OFFSET_TEN_BIT) {
1298		info.addr &= ~I2C_ADDR_OFFSET_TEN_BIT;
1299		info.flags |= I2C_CLIENT_TEN;
1300	}
1301
1302	if (info.addr & I2C_ADDR_OFFSET_SLAVE) {
1303		info.addr &= ~I2C_ADDR_OFFSET_SLAVE;
1304		info.flags |= I2C_CLIENT_SLAVE;
1305	}
1306
1307	client = i2c_new_client_device(adap, &info);
1308	if (IS_ERR(client))
1309		return PTR_ERR(client);
1310
1311	/* Keep track of the added device */
1312	mutex_lock(&adap->userspace_clients_lock);
1313	list_add_tail(&client->detected, &adap->userspace_clients);
1314	mutex_unlock(&adap->userspace_clients_lock);
1315	dev_info(dev, "%s: Instantiated device %s at 0x%02hx\n", "new_device",
1316		 info.type, info.addr);
1317
1318	return count;
1319}
1320static DEVICE_ATTR_WO(new_device);
1321
1322/*
1323 * And of course let the users delete the devices they instantiated, if
1324 * they got it wrong. This interface can only be used to delete devices
1325 * instantiated by i2c_sysfs_new_device above. This guarantees that we
1326 * don't delete devices to which some kernel code still has references.
1327 *
1328 * Parameter checking may look overzealous, but we really don't want
1329 * the user to delete the wrong device.
1330 */
1331static ssize_t
1332delete_device_store(struct device *dev, struct device_attribute *attr,
1333		    const char *buf, size_t count)
1334{
1335	struct i2c_adapter *adap = to_i2c_adapter(dev);
1336	struct i2c_client *client, *next;
1337	unsigned short addr;
1338	char end;
1339	int res;
1340
1341	/* Parse parameters, reject extra parameters */
1342	res = sscanf(buf, "%hi%c", &addr, &end);
1343	if (res < 1) {
1344		dev_err(dev, "%s: Can't parse I2C address\n", "delete_device");
1345		return -EINVAL;
1346	}
1347	if (res > 1  && end != '\n') {
1348		dev_err(dev, "%s: Extra parameters\n", "delete_device");
1349		return -EINVAL;
1350	}
1351
1352	/* Make sure the device was added through sysfs */
1353	res = -ENOENT;
1354	mutex_lock_nested(&adap->userspace_clients_lock,
1355			  i2c_adapter_depth(adap));
1356	list_for_each_entry_safe(client, next, &adap->userspace_clients,
1357				 detected) {
1358		if (i2c_encode_flags_to_addr(client) == addr) {
1359			dev_info(dev, "%s: Deleting device %s at 0x%02hx\n",
1360				 "delete_device", client->name, client->addr);
1361
1362			list_del(&client->detected);
1363			i2c_unregister_device(client);
1364			res = count;
1365			break;
1366		}
1367	}
1368	mutex_unlock(&adap->userspace_clients_lock);
1369
1370	if (res < 0)
1371		dev_err(dev, "%s: Can't find device in list\n",
1372			"delete_device");
1373	return res;
1374}
1375static DEVICE_ATTR_IGNORE_LOCKDEP(delete_device, S_IWUSR, NULL,
1376				  delete_device_store);
1377
1378static struct attribute *i2c_adapter_attrs[] = {
1379	&dev_attr_name.attr,
1380	&dev_attr_new_device.attr,
1381	&dev_attr_delete_device.attr,
1382	NULL
1383};
1384ATTRIBUTE_GROUPS(i2c_adapter);
1385
1386const struct device_type i2c_adapter_type = {
1387	.groups		= i2c_adapter_groups,
1388	.release	= i2c_adapter_dev_release,
1389};
1390EXPORT_SYMBOL_GPL(i2c_adapter_type);
1391
1392/**
1393 * i2c_verify_adapter - return parameter as i2c_adapter or NULL
1394 * @dev: device, probably from some driver model iterator
1395 *
1396 * When traversing the driver model tree, perhaps using driver model
1397 * iterators like @device_for_each_child(), you can't assume very much
1398 * about the nodes you find.  Use this function to avoid oopses caused
1399 * by wrongly treating some non-I2C device as an i2c_adapter.
1400 */
1401struct i2c_adapter *i2c_verify_adapter(struct device *dev)
1402{
1403	return (dev->type == &i2c_adapter_type)
1404			? to_i2c_adapter(dev)
1405			: NULL;
1406}
1407EXPORT_SYMBOL(i2c_verify_adapter);
1408
1409static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
1410{
1411	struct i2c_devinfo	*devinfo;
1412
1413	down_read(&__i2c_board_lock);
1414	list_for_each_entry(devinfo, &__i2c_board_list, list) {
1415		if (devinfo->busnum == adapter->nr &&
1416		    IS_ERR(i2c_new_client_device(adapter, &devinfo->board_info)))
1417			dev_err(&adapter->dev,
1418				"Can't create device at 0x%02x\n",
1419				devinfo->board_info.addr);
1420	}
1421	up_read(&__i2c_board_lock);
1422}
1423
1424static int i2c_do_add_adapter(struct i2c_driver *driver,
1425			      struct i2c_adapter *adap)
1426{
1427	/* Detect supported devices on that bus, and instantiate them */
1428	i2c_detect(adap, driver);
1429
1430	return 0;
1431}
1432
1433static int __process_new_adapter(struct device_driver *d, void *data)
1434{
1435	return i2c_do_add_adapter(to_i2c_driver(d), data);
1436}
1437
1438static const struct i2c_lock_operations i2c_adapter_lock_ops = {
1439	.lock_bus =    i2c_adapter_lock_bus,
1440	.trylock_bus = i2c_adapter_trylock_bus,
1441	.unlock_bus =  i2c_adapter_unlock_bus,
1442};
1443
1444static void i2c_host_notify_irq_teardown(struct i2c_adapter *adap)
1445{
1446	struct irq_domain *domain = adap->host_notify_domain;
1447	irq_hw_number_t hwirq;
1448
1449	if (!domain)
1450		return;
1451
1452	for (hwirq = 0 ; hwirq < I2C_ADDR_7BITS_COUNT ; hwirq++)
1453		irq_dispose_mapping(irq_find_mapping(domain, hwirq));
1454
1455	irq_domain_remove(domain);
1456	adap->host_notify_domain = NULL;
1457}
1458
1459static int i2c_host_notify_irq_map(struct irq_domain *h,
1460					  unsigned int virq,
1461					  irq_hw_number_t hw_irq_num)
1462{
1463	irq_set_chip_and_handler(virq, &dummy_irq_chip, handle_simple_irq);
1464
1465	return 0;
1466}
1467
1468static const struct irq_domain_ops i2c_host_notify_irq_ops = {
1469	.map = i2c_host_notify_irq_map,
1470};
1471
1472static int i2c_setup_host_notify_irq_domain(struct i2c_adapter *adap)
1473{
1474	struct irq_domain *domain;
1475
1476	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
1477		return 0;
1478
1479	domain = irq_domain_create_linear(adap->dev.parent->fwnode,
1480					  I2C_ADDR_7BITS_COUNT,
1481					  &i2c_host_notify_irq_ops, adap);
1482	if (!domain)
1483		return -ENOMEM;
1484
1485	adap->host_notify_domain = domain;
1486
1487	return 0;
1488}
1489
1490/**
1491 * i2c_handle_smbus_host_notify - Forward a Host Notify event to the correct
1492 * I2C client.
1493 * @adap: the adapter
1494 * @addr: the I2C address of the notifying device
1495 * Context: can't sleep
1496 *
1497 * Helper function to be called from an I2C bus driver's interrupt
1498 * handler. It will schedule the Host Notify IRQ.
1499 */
1500int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
1501{
1502	int irq;
1503
1504	if (!adap)
1505		return -EINVAL;
1506
1507	dev_dbg(&adap->dev, "Detected HostNotify from address 0x%02x", addr);
1508
1509	irq = irq_find_mapping(adap->host_notify_domain, addr);
1510	if (irq <= 0)
1511		return -ENXIO;
1512
1513	generic_handle_irq_safe(irq);
1514
1515	return 0;
1516}
1517EXPORT_SYMBOL_GPL(i2c_handle_smbus_host_notify);
1518
1519static int i2c_register_adapter(struct i2c_adapter *adap)
1520{
1521	int res = -EINVAL;
1522
1523	/* Can't register until after driver model init */
1524	if (WARN_ON(!is_registered)) {
1525		res = -EAGAIN;
1526		goto out_list;
1527	}
1528
1529	/* Sanity checks */
1530	if (WARN(!adap->name[0], "i2c adapter has no name"))
1531		goto out_list;
1532
1533	if (!adap->algo) {
1534		pr_err("adapter '%s': no algo supplied!\n", adap->name);
1535		goto out_list;
1536	}
1537
1538	if (!adap->lock_ops)
1539		adap->lock_ops = &i2c_adapter_lock_ops;
1540
1541	adap->locked_flags = 0;
1542	rt_mutex_init(&adap->bus_lock);
1543	rt_mutex_init(&adap->mux_lock);
1544	mutex_init(&adap->userspace_clients_lock);
1545	INIT_LIST_HEAD(&adap->userspace_clients);
1546
1547	/* Set default timeout to 1 second if not already set */
1548	if (adap->timeout == 0)
1549		adap->timeout = HZ;
1550
1551	/* register soft irqs for Host Notify */
1552	res = i2c_setup_host_notify_irq_domain(adap);
1553	if (res) {
1554		pr_err("adapter '%s': can't create Host Notify IRQs (%d)\n",
1555		       adap->name, res);
1556		goto out_list;
1557	}
1558
1559	dev_set_name(&adap->dev, "i2c-%d", adap->nr);
1560	adap->dev.bus = &i2c_bus_type;
1561	adap->dev.type = &i2c_adapter_type;
1562	device_initialize(&adap->dev);
1563
1564	/*
1565	 * This adapter can be used as a parent immediately after device_add(),
1566	 * setup runtime-pm (especially ignore-children) before hand.
1567	 */
1568	device_enable_async_suspend(&adap->dev);
1569	pm_runtime_no_callbacks(&adap->dev);
1570	pm_suspend_ignore_children(&adap->dev, true);
1571	pm_runtime_enable(&adap->dev);
1572
1573	res = device_add(&adap->dev);
1574	if (res) {
1575		pr_err("adapter '%s': can't register device (%d)\n", adap->name, res);
1576		put_device(&adap->dev);
1577		goto out_list;
1578	}
1579
1580	adap->debugfs = debugfs_create_dir(dev_name(&adap->dev), i2c_debugfs_root);
1581
1582	res = i2c_setup_smbus_alert(adap);
1583	if (res)
1584		goto out_reg;
1585
1586	res = i2c_init_recovery(adap);
1587	if (res == -EPROBE_DEFER)
1588		goto out_reg;
1589
1590	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
1591
1592	/* create pre-declared device nodes */
1593	of_i2c_register_devices(adap);
1594	i2c_acpi_install_space_handler(adap);
1595	i2c_acpi_register_devices(adap);
1596
1597	if (adap->nr < __i2c_first_dynamic_bus_num)
1598		i2c_scan_static_board_info(adap);
1599
1600	/* Notify drivers */
1601	mutex_lock(&core_lock);
1602	bus_for_each_drv(&i2c_bus_type, NULL, adap, __process_new_adapter);
1603	mutex_unlock(&core_lock);
1604
1605	return 0;
1606
1607out_reg:
1608	debugfs_remove_recursive(adap->debugfs);
1609	init_completion(&adap->dev_released);
1610	device_unregister(&adap->dev);
1611	wait_for_completion(&adap->dev_released);
1612out_list:
1613	mutex_lock(&core_lock);
1614	idr_remove(&i2c_adapter_idr, adap->nr);
1615	mutex_unlock(&core_lock);
1616	return res;
1617}
1618
1619/**
1620 * __i2c_add_numbered_adapter - i2c_add_numbered_adapter where nr is never -1
1621 * @adap: the adapter to register (with adap->nr initialized)
1622 * Context: can sleep
1623 *
1624 * See i2c_add_numbered_adapter() for details.
1625 */
1626static int __i2c_add_numbered_adapter(struct i2c_adapter *adap)
1627{
1628	int id;
1629
1630	mutex_lock(&core_lock);
1631	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1, GFP_KERNEL);
1632	mutex_unlock(&core_lock);
1633	if (WARN(id < 0, "couldn't get idr"))
1634		return id == -ENOSPC ? -EBUSY : id;
1635
1636	return i2c_register_adapter(adap);
1637}
1638
1639/**
1640 * i2c_add_adapter - declare i2c adapter, use dynamic bus number
1641 * @adapter: the adapter to add
1642 * Context: can sleep
1643 *
1644 * This routine is used to declare an I2C adapter when its bus number
1645 * doesn't matter or when its bus number is specified by an dt alias.
1646 * Examples of bases when the bus number doesn't matter: I2C adapters
1647 * dynamically added by USB links or PCI plugin cards.
1648 *
1649 * When this returns zero, a new bus number was allocated and stored
1650 * in adap->nr, and the specified adapter became available for clients.
1651 * Otherwise, a negative errno value is returned.
1652 */
1653int i2c_add_adapter(struct i2c_adapter *adapter)
1654{
1655	struct device *dev = &adapter->dev;
1656	int id;
1657
1658	id = of_alias_get_id(dev->of_node, "i2c");
1659	if (id >= 0) {
1660		adapter->nr = id;
1661		return __i2c_add_numbered_adapter(adapter);
1662	}
1663
1664	mutex_lock(&core_lock);
1665	id = idr_alloc(&i2c_adapter_idr, adapter,
1666		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
1667	mutex_unlock(&core_lock);
1668	if (WARN(id < 0, "couldn't get idr"))
1669		return id;
1670
1671	adapter->nr = id;
1672
1673	return i2c_register_adapter(adapter);
1674}
1675EXPORT_SYMBOL(i2c_add_adapter);
1676
1677/**
1678 * i2c_add_numbered_adapter - declare i2c adapter, use static bus number
1679 * @adap: the adapter to register (with adap->nr initialized)
1680 * Context: can sleep
1681 *
1682 * This routine is used to declare an I2C adapter when its bus number
1683 * matters.  For example, use it for I2C adapters from system-on-chip CPUs,
1684 * or otherwise built in to the system's mainboard, and where i2c_board_info
1685 * is used to properly configure I2C devices.
1686 *
1687 * If the requested bus number is set to -1, then this function will behave
1688 * identically to i2c_add_adapter, and will dynamically assign a bus number.
1689 *
1690 * If no devices have pre-been declared for this bus, then be sure to
1691 * register the adapter before any dynamically allocated ones.  Otherwise
1692 * the required bus ID may not be available.
1693 *
1694 * When this returns zero, the specified adapter became available for
1695 * clients using the bus number provided in adap->nr.  Also, the table
1696 * of I2C devices pre-declared using i2c_register_board_info() is scanned,
1697 * and the appropriate driver model device nodes are created.  Otherwise, a
1698 * negative errno value is returned.
1699 */
1700int i2c_add_numbered_adapter(struct i2c_adapter *adap)
1701{
1702	if (adap->nr == -1) /* -1 means dynamically assign bus id */
1703		return i2c_add_adapter(adap);
1704
1705	return __i2c_add_numbered_adapter(adap);
1706}
1707EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
1708
1709static void i2c_do_del_adapter(struct i2c_driver *driver,
1710			      struct i2c_adapter *adapter)
1711{
1712	struct i2c_client *client, *_n;
1713
1714	/* Remove the devices we created ourselves as the result of hardware
1715	 * probing (using a driver's detect method) */
1716	list_for_each_entry_safe(client, _n, &driver->clients, detected) {
1717		if (client->adapter == adapter) {
1718			dev_dbg(&adapter->dev, "Removing %s at 0x%x\n",
1719				client->name, client->addr);
1720			list_del(&client->detected);
1721			i2c_unregister_device(client);
1722		}
1723	}
1724}
1725
1726static int __unregister_client(struct device *dev, void *dummy)
1727{
1728	struct i2c_client *client = i2c_verify_client(dev);
1729	if (client && strcmp(client->name, "dummy"))
1730		i2c_unregister_device(client);
1731	return 0;
1732}
1733
1734static int __unregister_dummy(struct device *dev, void *dummy)
1735{
1736	struct i2c_client *client = i2c_verify_client(dev);
1737	i2c_unregister_device(client);
1738	return 0;
1739}
1740
1741static int __process_removed_adapter(struct device_driver *d, void *data)
1742{
1743	i2c_do_del_adapter(to_i2c_driver(d), data);
1744	return 0;
1745}
1746
1747/**
1748 * i2c_del_adapter - unregister I2C adapter
1749 * @adap: the adapter being unregistered
1750 * Context: can sleep
1751 *
1752 * This unregisters an I2C adapter which was previously registered
1753 * by @i2c_add_adapter or @i2c_add_numbered_adapter.
1754 */
1755void i2c_del_adapter(struct i2c_adapter *adap)
1756{
1757	struct i2c_adapter *found;
1758	struct i2c_client *client, *next;
1759
1760	/* First make sure that this adapter was ever added */
1761	mutex_lock(&core_lock);
1762	found = idr_find(&i2c_adapter_idr, adap->nr);
1763	mutex_unlock(&core_lock);
1764	if (found != adap) {
1765		pr_debug("attempting to delete unregistered adapter [%s]\n", adap->name);
1766		return;
1767	}
1768
1769	i2c_acpi_remove_space_handler(adap);
1770	/* Tell drivers about this removal */
1771	mutex_lock(&core_lock);
1772	bus_for_each_drv(&i2c_bus_type, NULL, adap,
1773			       __process_removed_adapter);
1774	mutex_unlock(&core_lock);
1775
1776	/* Remove devices instantiated from sysfs */
1777	mutex_lock_nested(&adap->userspace_clients_lock,
1778			  i2c_adapter_depth(adap));
1779	list_for_each_entry_safe(client, next, &adap->userspace_clients,
1780				 detected) {
1781		dev_dbg(&adap->dev, "Removing %s at 0x%x\n", client->name,
1782			client->addr);
1783		list_del(&client->detected);
1784		i2c_unregister_device(client);
1785	}
1786	mutex_unlock(&adap->userspace_clients_lock);
1787
1788	/* Detach any active clients. This can't fail, thus we do not
1789	 * check the returned value. This is a two-pass process, because
1790	 * we can't remove the dummy devices during the first pass: they
1791	 * could have been instantiated by real devices wishing to clean
1792	 * them up properly, so we give them a chance to do that first. */
1793	device_for_each_child(&adap->dev, NULL, __unregister_client);
1794	device_for_each_child(&adap->dev, NULL, __unregister_dummy);
1795
1796	/* device name is gone after device_unregister */
1797	dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
1798
1799	pm_runtime_disable(&adap->dev);
1800
1801	i2c_host_notify_irq_teardown(adap);
1802
1803	debugfs_remove_recursive(adap->debugfs);
1804
1805	/* wait until all references to the device are gone
1806	 *
1807	 * FIXME: This is old code and should ideally be replaced by an
1808	 * alternative which results in decoupling the lifetime of the struct
1809	 * device from the i2c_adapter, like spi or netdev do. Any solution
1810	 * should be thoroughly tested with DEBUG_KOBJECT_RELEASE enabled!
1811	 */
1812	init_completion(&adap->dev_released);
1813	device_unregister(&adap->dev);
1814	wait_for_completion(&adap->dev_released);
1815
1816	/* free bus id */
1817	mutex_lock(&core_lock);
1818	idr_remove(&i2c_adapter_idr, adap->nr);
1819	mutex_unlock(&core_lock);
1820
1821	/* Clear the device structure in case this adapter is ever going to be
1822	   added again */
1823	memset(&adap->dev, 0, sizeof(adap->dev));
1824}
1825EXPORT_SYMBOL(i2c_del_adapter);
1826
1827static void devm_i2c_del_adapter(void *adapter)
1828{
1829	i2c_del_adapter(adapter);
1830}
1831
1832/**
1833 * devm_i2c_add_adapter - device-managed variant of i2c_add_adapter()
1834 * @dev: managing device for adding this I2C adapter
1835 * @adapter: the adapter to add
1836 * Context: can sleep
1837 *
1838 * Add adapter with dynamic bus number, same with i2c_add_adapter()
1839 * but the adapter will be auto deleted on driver detach.
1840 */
1841int devm_i2c_add_adapter(struct device *dev, struct i2c_adapter *adapter)
1842{
1843	int ret;
1844
1845	ret = i2c_add_adapter(adapter);
1846	if (ret)
1847		return ret;
1848
1849	return devm_add_action_or_reset(dev, devm_i2c_del_adapter, adapter);
1850}
1851EXPORT_SYMBOL_GPL(devm_i2c_add_adapter);
1852
1853static int i2c_dev_or_parent_fwnode_match(struct device *dev, const void *data)
1854{
1855	if (dev_fwnode(dev) == data)
1856		return 1;
1857
1858	if (dev->parent && dev_fwnode(dev->parent) == data)
1859		return 1;
1860
1861	return 0;
1862}
1863
1864/**
1865 * i2c_find_adapter_by_fwnode() - find an i2c_adapter for the fwnode
1866 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter
1867 *
1868 * Look up and return the &struct i2c_adapter corresponding to the @fwnode.
1869 * If no adapter can be found, or @fwnode is NULL, this returns NULL.
1870 *
1871 * The user must call put_device(&adapter->dev) once done with the i2c adapter.
1872 */
1873struct i2c_adapter *i2c_find_adapter_by_fwnode(struct fwnode_handle *fwnode)
1874{
1875	struct i2c_adapter *adapter;
1876	struct device *dev;
1877
1878	if (!fwnode)
1879		return NULL;
1880
1881	dev = bus_find_device(&i2c_bus_type, NULL, fwnode,
1882			      i2c_dev_or_parent_fwnode_match);
1883	if (!dev)
1884		return NULL;
1885
1886	adapter = i2c_verify_adapter(dev);
1887	if (!adapter)
1888		put_device(dev);
1889
1890	return adapter;
1891}
1892EXPORT_SYMBOL(i2c_find_adapter_by_fwnode);
1893
1894/**
1895 * i2c_get_adapter_by_fwnode() - find an i2c_adapter for the fwnode
1896 * @fwnode: &struct fwnode_handle corresponding to the &struct i2c_adapter
1897 *
1898 * Look up and return the &struct i2c_adapter corresponding to the @fwnode,
1899 * and increment the adapter module's use count. If no adapter can be found,
1900 * or @fwnode is NULL, this returns NULL.
1901 *
1902 * The user must call i2c_put_adapter(adapter) once done with the i2c adapter.
1903 * Note that this is different from i2c_find_adapter_by_node().
1904 */
1905struct i2c_adapter *i2c_get_adapter_by_fwnode(struct fwnode_handle *fwnode)
1906{
1907	struct i2c_adapter *adapter;
1908
1909	adapter = i2c_find_adapter_by_fwnode(fwnode);
1910	if (!adapter)
1911		return NULL;
1912
1913	if (!try_module_get(adapter->owner)) {
1914		put_device(&adapter->dev);
1915		adapter = NULL;
1916	}
1917
1918	return adapter;
1919}
1920EXPORT_SYMBOL(i2c_get_adapter_by_fwnode);
1921
1922static void i2c_parse_timing(struct device *dev, char *prop_name, u32 *cur_val_p,
1923			    u32 def_val, bool use_def)
1924{
1925	int ret;
1926
1927	ret = device_property_read_u32(dev, prop_name, cur_val_p);
1928	if (ret && use_def)
1929		*cur_val_p = def_val;
1930
1931	dev_dbg(dev, "%s: %u\n", prop_name, *cur_val_p);
1932}
1933
1934/**
1935 * i2c_parse_fw_timings - get I2C related timing parameters from firmware
1936 * @dev: The device to scan for I2C timing properties
1937 * @t: the i2c_timings struct to be filled with values
1938 * @use_defaults: bool to use sane defaults derived from the I2C specification
1939 *		  when properties are not found, otherwise don't update
1940 *
1941 * Scan the device for the generic I2C properties describing timing parameters
1942 * for the signal and fill the given struct with the results. If a property was
1943 * not found and use_defaults was true, then maximum timings are assumed which
1944 * are derived from the I2C specification. If use_defaults is not used, the
1945 * results will be as before, so drivers can apply their own defaults before
1946 * calling this helper. The latter is mainly intended for avoiding regressions
1947 * of existing drivers which want to switch to this function. New drivers
1948 * almost always should use the defaults.
1949 */
1950void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_defaults)
1951{
1952	bool u = use_defaults;
1953	u32 d;
1954
1955	i2c_parse_timing(dev, "clock-frequency", &t->bus_freq_hz,
1956			 I2C_MAX_STANDARD_MODE_FREQ, u);
1957
1958	d = t->bus_freq_hz <= I2C_MAX_STANDARD_MODE_FREQ ? 1000 :
1959	    t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120;
1960	i2c_parse_timing(dev, "i2c-scl-rising-time-ns", &t->scl_rise_ns, d, u);
1961
1962	d = t->bus_freq_hz <= I2C_MAX_FAST_MODE_FREQ ? 300 : 120;
1963	i2c_parse_timing(dev, "i2c-scl-falling-time-ns", &t->scl_fall_ns, d, u);
1964
1965	i2c_parse_timing(dev, "i2c-scl-internal-delay-ns",
1966			 &t->scl_int_delay_ns, 0, u);
1967	i2c_parse_timing(dev, "i2c-sda-falling-time-ns", &t->sda_fall_ns,
1968			 t->scl_fall_ns, u);
1969	i2c_parse_timing(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns, 0, u);
1970	i2c_parse_timing(dev, "i2c-digital-filter-width-ns",
1971			 &t->digital_filter_width_ns, 0, u);
1972	i2c_parse_timing(dev, "i2c-analog-filter-cutoff-frequency",
1973			 &t->analog_filter_cutoff_freq_hz, 0, u);
1974}
1975EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
1976
1977/* ------------------------------------------------------------------------- */
1978
1979int i2c_for_each_dev(void *data, int (*fn)(struct device *dev, void *data))
1980{
1981	int res;
1982
1983	mutex_lock(&core_lock);
1984	res = bus_for_each_dev(&i2c_bus_type, NULL, data, fn);
1985	mutex_unlock(&core_lock);
1986
1987	return res;
1988}
1989EXPORT_SYMBOL_GPL(i2c_for_each_dev);
1990
1991static int __process_new_driver(struct device *dev, void *data)
1992{
1993	if (dev->type != &i2c_adapter_type)
1994		return 0;
1995	return i2c_do_add_adapter(data, to_i2c_adapter(dev));
1996}
1997
1998/*
1999 * An i2c_driver is used with one or more i2c_client (device) nodes to access
2000 * i2c slave chips, on a bus instance associated with some i2c_adapter.
2001 */
2002
2003int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
2004{
2005	int res;
2006
2007	/* Can't register until after driver model init */
2008	if (WARN_ON(!is_registered))
2009		return -EAGAIN;
2010
2011	/* add the driver to the list of i2c drivers in the driver core */
2012	driver->driver.owner = owner;
2013	driver->driver.bus = &i2c_bus_type;
2014	INIT_LIST_HEAD(&driver->clients);
2015
2016	/* When registration returns, the driver core
2017	 * will have called probe() for all matching-but-unbound devices.
2018	 */
2019	res = driver_register(&driver->driver);
2020	if (res)
2021		return res;
2022
2023	pr_debug("driver [%s] registered\n", driver->driver.name);
2024
2025	/* Walk the adapters that are already present */
2026	i2c_for_each_dev(driver, __process_new_driver);
2027
2028	return 0;
2029}
2030EXPORT_SYMBOL(i2c_register_driver);
2031
2032static int __process_removed_driver(struct device *dev, void *data)
2033{
2034	if (dev->type == &i2c_adapter_type)
2035		i2c_do_del_adapter(data, to_i2c_adapter(dev));
2036	return 0;
2037}
2038
2039/**
2040 * i2c_del_driver - unregister I2C driver
2041 * @driver: the driver being unregistered
2042 * Context: can sleep
2043 */
2044void i2c_del_driver(struct i2c_driver *driver)
2045{
2046	i2c_for_each_dev(driver, __process_removed_driver);
2047
2048	driver_unregister(&driver->driver);
2049	pr_debug("driver [%s] unregistered\n", driver->driver.name);
2050}
2051EXPORT_SYMBOL(i2c_del_driver);
2052
2053/* ------------------------------------------------------------------------- */
2054
2055struct i2c_cmd_arg {
2056	unsigned	cmd;
2057	void		*arg;
2058};
2059
2060static int i2c_cmd(struct device *dev, void *_arg)
2061{
2062	struct i2c_client	*client = i2c_verify_client(dev);
2063	struct i2c_cmd_arg	*arg = _arg;
2064	struct i2c_driver	*driver;
2065
2066	if (!client || !client->dev.driver)
2067		return 0;
2068
2069	driver = to_i2c_driver(client->dev.driver);
2070	if (driver->command)
2071		driver->command(client, arg->cmd, arg->arg);
2072	return 0;
2073}
2074
2075void i2c_clients_command(struct i2c_adapter *adap, unsigned int cmd, void *arg)
2076{
2077	struct i2c_cmd_arg	cmd_arg;
2078
2079	cmd_arg.cmd = cmd;
2080	cmd_arg.arg = arg;
2081	device_for_each_child(&adap->dev, &cmd_arg, i2c_cmd);
2082}
2083EXPORT_SYMBOL(i2c_clients_command);
2084
2085static int __init i2c_init(void)
2086{
2087	int retval;
2088
2089	retval = of_alias_get_highest_id("i2c");
2090
2091	down_write(&__i2c_board_lock);
2092	if (retval >= __i2c_first_dynamic_bus_num)
2093		__i2c_first_dynamic_bus_num = retval + 1;
2094	up_write(&__i2c_board_lock);
2095
2096	retval = bus_register(&i2c_bus_type);
2097	if (retval)
2098		return retval;
2099
2100	is_registered = true;
2101
2102	i2c_debugfs_root = debugfs_create_dir("i2c", NULL);
2103
2104	retval = i2c_add_driver(&dummy_driver);
2105	if (retval)
2106		goto class_err;
2107
2108	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2109		WARN_ON(of_reconfig_notifier_register(&i2c_of_notifier));
2110	if (IS_ENABLED(CONFIG_ACPI))
2111		WARN_ON(acpi_reconfig_notifier_register(&i2c_acpi_notifier));
2112
2113	return 0;
2114
2115class_err:
2116	is_registered = false;
2117	bus_unregister(&i2c_bus_type);
2118	return retval;
2119}
2120
2121static void __exit i2c_exit(void)
2122{
2123	if (IS_ENABLED(CONFIG_ACPI))
2124		WARN_ON(acpi_reconfig_notifier_unregister(&i2c_acpi_notifier));
2125	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2126		WARN_ON(of_reconfig_notifier_unregister(&i2c_of_notifier));
2127	i2c_del_driver(&dummy_driver);
2128	debugfs_remove_recursive(i2c_debugfs_root);
2129	bus_unregister(&i2c_bus_type);
2130	tracepoint_synchronize_unregister();
2131}
2132
2133/* We must initialize early, because some subsystems register i2c drivers
2134 * in subsys_initcall() code, but are linked (and initialized) before i2c.
2135 */
2136postcore_initcall(i2c_init);
2137module_exit(i2c_exit);
2138
2139/* ----------------------------------------------------
2140 * the functional interface to the i2c busses.
2141 * ----------------------------------------------------
2142 */
2143
2144/* Check if val is exceeding the quirk IFF quirk is non 0 */
2145#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
2146
2147static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
2148{
2149	dev_err_ratelimited(&adap->dev, "adapter quirk: %s (addr 0x%04x, size %u, %s)\n",
2150			    err_msg, msg->addr, msg->len,
2151			    str_read_write(msg->flags & I2C_M_RD));
2152	return -EOPNOTSUPP;
2153}
2154
2155static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2156{
2157	const struct i2c_adapter_quirks *q = adap->quirks;
2158	int max_num = q->max_num_msgs, i;
2159	bool do_len_check = true;
2160
2161	if (q->flags & I2C_AQ_COMB) {
2162		max_num = 2;
2163
2164		/* special checks for combined messages */
2165		if (num == 2) {
2166			if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
2167				return i2c_quirk_error(adap, &msgs[0], "1st comb msg must be write");
2168
2169			if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
2170				return i2c_quirk_error(adap, &msgs[1], "2nd comb msg must be read");
2171
2172			if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
2173				return i2c_quirk_error(adap, &msgs[0], "comb msg only to same addr");
2174
2175			if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
2176				return i2c_quirk_error(adap, &msgs[0], "msg too long");
2177
2178			if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
2179				return i2c_quirk_error(adap, &msgs[1], "msg too long");
2180
2181			do_len_check = false;
2182		}
2183	}
2184
2185	if (i2c_quirk_exceeded(num, max_num))
2186		return i2c_quirk_error(adap, &msgs[0], "too many messages");
2187
2188	for (i = 0; i < num; i++) {
2189		u16 len = msgs[i].len;
2190
2191		if (msgs[i].flags & I2C_M_RD) {
2192			if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
2193				return i2c_quirk_error(adap, &msgs[i], "msg too long");
2194
2195			if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0)
2196				return i2c_quirk_error(adap, &msgs[i], "no zero length");
2197		} else {
2198			if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
2199				return i2c_quirk_error(adap, &msgs[i], "msg too long");
2200
2201			if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0)
2202				return i2c_quirk_error(adap, &msgs[i], "no zero length");
2203		}
2204	}
2205
2206	return 0;
2207}
2208
2209/**
2210 * __i2c_transfer - unlocked flavor of i2c_transfer
2211 * @adap: Handle to I2C bus
2212 * @msgs: One or more messages to execute before STOP is issued to
2213 *	terminate the operation; each message begins with a START.
2214 * @num: Number of messages to be executed.
2215 *
2216 * Returns negative errno, else the number of messages executed.
2217 *
2218 * Adapter lock must be held when calling this function. No debug logging
2219 * takes place.
2220 */
2221int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2222{
2223	unsigned long orig_jiffies;
2224	int ret, try;
2225
2226	if (!adap->algo->master_xfer) {
2227		dev_dbg(&adap->dev, "I2C level transfers not supported\n");
2228		return -EOPNOTSUPP;
2229	}
2230
2231	if (WARN_ON(!msgs || num < 1))
2232		return -EINVAL;
2233
2234	ret = __i2c_check_suspended(adap);
2235	if (ret)
2236		return ret;
2237
2238	if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
2239		return -EOPNOTSUPP;
2240
2241	/*
2242	 * i2c_trace_msg_key gets enabled when tracepoint i2c_transfer gets
2243	 * enabled.  This is an efficient way of keeping the for-loop from
2244	 * being executed when not needed.
2245	 */
2246	if (static_branch_unlikely(&i2c_trace_msg_key)) {
2247		int i;
2248		for (i = 0; i < num; i++)
2249			if (msgs[i].flags & I2C_M_RD)
2250				trace_i2c_read(adap, &msgs[i], i);
2251			else
2252				trace_i2c_write(adap, &msgs[i], i);
2253	}
2254
2255	/* Retry automatically on arbitration loss */
2256	orig_jiffies = jiffies;
2257	for (ret = 0, try = 0; try <= adap->retries; try++) {
2258		if (i2c_in_atomic_xfer_mode() && adap->algo->master_xfer_atomic)
2259			ret = adap->algo->master_xfer_atomic(adap, msgs, num);
2260		else
2261			ret = adap->algo->master_xfer(adap, msgs, num);
2262
2263		if (ret != -EAGAIN)
2264			break;
2265		if (time_after(jiffies, orig_jiffies + adap->timeout))
2266			break;
2267	}
2268
2269	if (static_branch_unlikely(&i2c_trace_msg_key)) {
2270		int i;
2271		for (i = 0; i < ret; i++)
2272			if (msgs[i].flags & I2C_M_RD)
2273				trace_i2c_reply(adap, &msgs[i], i);
2274		trace_i2c_result(adap, num, ret);
2275	}
2276
2277	return ret;
2278}
2279EXPORT_SYMBOL(__i2c_transfer);
2280
2281/**
2282 * i2c_transfer - execute a single or combined I2C message
2283 * @adap: Handle to I2C bus
2284 * @msgs: One or more messages to execute before STOP is issued to
2285 *	terminate the operation; each message begins with a START.
2286 * @num: Number of messages to be executed.
2287 *
2288 * Returns negative errno, else the number of messages executed.
2289 *
2290 * Note that there is no requirement that each message be sent to
2291 * the same slave address, although that is the most common model.
2292 */
2293int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
2294{
2295	int ret;
2296
2297	/* REVISIT the fault reporting model here is weak:
2298	 *
2299	 *  - When we get an error after receiving N bytes from a slave,
2300	 *    there is no way to report "N".
2301	 *
2302	 *  - When we get a NAK after transmitting N bytes to a slave,
2303	 *    there is no way to report "N" ... or to let the master
2304	 *    continue executing the rest of this combined message, if
2305	 *    that's the appropriate response.
2306	 *
2307	 *  - When for example "num" is two and we successfully complete
2308	 *    the first message but get an error part way through the
2309	 *    second, it's unclear whether that should be reported as
2310	 *    one (discarding status on the second message) or errno
2311	 *    (discarding status on the first one).
2312	 */
2313	ret = __i2c_lock_bus_helper(adap);
2314	if (ret)
2315		return ret;
2316
2317	ret = __i2c_transfer(adap, msgs, num);
2318	i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
2319
2320	return ret;
2321}
2322EXPORT_SYMBOL(i2c_transfer);
2323
2324/**
2325 * i2c_transfer_buffer_flags - issue a single I2C message transferring data
2326 *			       to/from a buffer
2327 * @client: Handle to slave device
2328 * @buf: Where the data is stored
2329 * @count: How many bytes to transfer, must be less than 64k since msg.len is u16
2330 * @flags: The flags to be used for the message, e.g. I2C_M_RD for reads
2331 *
2332 * Returns negative errno, or else the number of bytes transferred.
2333 */
2334int i2c_transfer_buffer_flags(const struct i2c_client *client, char *buf,
2335			      int count, u16 flags)
2336{
2337	int ret;
2338	struct i2c_msg msg = {
2339		.addr = client->addr,
2340		.flags = flags | (client->flags & I2C_M_TEN),
2341		.len = count,
2342		.buf = buf,
2343	};
2344
2345	ret = i2c_transfer(client->adapter, &msg, 1);
2346
2347	/*
2348	 * If everything went ok (i.e. 1 msg transferred), return #bytes
2349	 * transferred, else error code.
2350	 */
2351	return (ret == 1) ? count : ret;
2352}
2353EXPORT_SYMBOL(i2c_transfer_buffer_flags);
2354
2355/**
2356 * i2c_get_device_id - get manufacturer, part id and die revision of a device
2357 * @client: The device to query
2358 * @id: The queried information
2359 *
2360 * Returns negative errno on error, zero on success.
2361 */
2362int i2c_get_device_id(const struct i2c_client *client,
2363		      struct i2c_device_identity *id)
2364{
2365	struct i2c_adapter *adap = client->adapter;
2366	union i2c_smbus_data raw_id;
2367	int ret;
2368
2369	if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
2370		return -EOPNOTSUPP;
2371
2372	raw_id.block[0] = 3;
2373	ret = i2c_smbus_xfer(adap, I2C_ADDR_DEVICE_ID, 0,
2374			     I2C_SMBUS_READ, client->addr << 1,
2375			     I2C_SMBUS_I2C_BLOCK_DATA, &raw_id);
2376	if (ret)
2377		return ret;
2378
2379	id->manufacturer_id = (raw_id.block[1] << 4) | (raw_id.block[2] >> 4);
2380	id->part_id = ((raw_id.block[2] & 0xf) << 5) | (raw_id.block[3] >> 3);
2381	id->die_revision = raw_id.block[3] & 0x7;
2382	return 0;
2383}
2384EXPORT_SYMBOL_GPL(i2c_get_device_id);
2385
2386/**
2387 * i2c_client_get_device_id - get the driver match table entry of a device
2388 * @client: the device to query. The device must be bound to a driver
2389 *
2390 * Returns a pointer to the matching entry if found, NULL otherwise.
2391 */
2392const struct i2c_device_id *i2c_client_get_device_id(const struct i2c_client *client)
2393{
2394	const struct i2c_driver *drv = to_i2c_driver(client->dev.driver);
2395
2396	return i2c_match_id(drv->id_table, client);
2397}
2398EXPORT_SYMBOL_GPL(i2c_client_get_device_id);
2399
2400/* ----------------------------------------------------
2401 * the i2c address scanning function
2402 * Will not work for 10-bit addresses!
2403 * ----------------------------------------------------
2404 */
2405
2406/*
2407 * Legacy default probe function, mostly relevant for SMBus. The default
2408 * probe method is a quick write, but it is known to corrupt the 24RF08
2409 * EEPROMs due to a state machine bug, and could also irreversibly
2410 * write-protect some EEPROMs, so for address ranges 0x30-0x37 and 0x50-0x5f,
2411 * we use a short byte read instead. Also, some bus drivers don't implement
2412 * quick write, so we fallback to a byte read in that case too.
2413 * On x86, there is another special case for FSC hardware monitoring chips,
2414 * which want regular byte reads (address 0x73.) Fortunately, these are the
2415 * only known chips using this I2C address on PC hardware.
2416 * Returns 1 if probe succeeded, 0 if not.
2417 */
2418static int i2c_default_probe(struct i2c_adapter *adap, unsigned short addr)
2419{
2420	int err;
2421	union i2c_smbus_data dummy;
2422
2423#ifdef CONFIG_X86
2424	if (addr == 0x73 && (adap->class & I2C_CLASS_HWMON)
2425	 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE_DATA))
2426		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2427				     I2C_SMBUS_BYTE_DATA, &dummy);
2428	else
2429#endif
2430	if (!((addr & ~0x07) == 0x30 || (addr & ~0x0f) == 0x50)
2431	 && i2c_check_functionality(adap, I2C_FUNC_SMBUS_QUICK))
2432		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_WRITE, 0,
2433				     I2C_SMBUS_QUICK, NULL);
2434	else if (i2c_check_functionality(adap, I2C_FUNC_SMBUS_READ_BYTE))
2435		err = i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2436				     I2C_SMBUS_BYTE, &dummy);
2437	else {
2438		dev_warn(&adap->dev, "No suitable probing method supported for address 0x%02X\n",
2439			 addr);
2440		err = -EOPNOTSUPP;
2441	}
2442
2443	return err >= 0;
2444}
2445
2446static int i2c_detect_address(struct i2c_client *temp_client,
2447			      struct i2c_driver *driver)
2448{
2449	struct i2c_board_info info;
2450	struct i2c_adapter *adapter = temp_client->adapter;
2451	int addr = temp_client->addr;
2452	int err;
2453
2454	/* Make sure the address is valid */
2455	err = i2c_check_7bit_addr_validity_strict(addr);
2456	if (err) {
2457		dev_warn(&adapter->dev, "Invalid probe address 0x%02x\n",
2458			 addr);
2459		return err;
2460	}
2461
2462	/* Skip if already in use (7 bit, no need to encode flags) */
2463	if (i2c_check_addr_busy(adapter, addr))
2464		return 0;
2465
2466	/* Make sure there is something at this address */
2467	if (!i2c_default_probe(adapter, addr))
2468		return 0;
2469
2470	/* Finally call the custom detection function */
2471	memset(&info, 0, sizeof(struct i2c_board_info));
2472	info.addr = addr;
2473	err = driver->detect(temp_client, &info);
2474	if (err) {
2475		/* -ENODEV is returned if the detection fails. We catch it
2476		   here as this isn't an error. */
2477		return err == -ENODEV ? 0 : err;
2478	}
2479
2480	/* Consistency check */
2481	if (info.type[0] == '\0') {
2482		dev_err(&adapter->dev,
2483			"%s detection function provided no name for 0x%x\n",
2484			driver->driver.name, addr);
2485	} else {
2486		struct i2c_client *client;
2487
2488		/* Detection succeeded, instantiate the device */
2489		if (adapter->class & I2C_CLASS_DEPRECATED)
2490			dev_warn(&adapter->dev,
2491				"This adapter will soon drop class based instantiation of devices. "
2492				"Please make sure client 0x%02x gets instantiated by other means. "
2493				"Check 'Documentation/i2c/instantiating-devices.rst' for details.\n",
2494				info.addr);
2495
2496		dev_dbg(&adapter->dev, "Creating %s at 0x%02x\n",
2497			info.type, info.addr);
2498		client = i2c_new_client_device(adapter, &info);
2499		if (!IS_ERR(client))
2500			list_add_tail(&client->detected, &driver->clients);
2501		else
2502			dev_err(&adapter->dev, "Failed creating %s at 0x%02x\n",
2503				info.type, info.addr);
2504	}
2505	return 0;
2506}
2507
2508static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
2509{
2510	const unsigned short *address_list;
2511	struct i2c_client *temp_client;
2512	int i, err = 0;
2513
2514	address_list = driver->address_list;
2515	if (!driver->detect || !address_list)
2516		return 0;
2517
2518	/* Warn that the adapter lost class based instantiation */
2519	if (adapter->class == I2C_CLASS_DEPRECATED) {
2520		dev_dbg(&adapter->dev,
2521			"This adapter dropped support for I2C classes and won't auto-detect %s devices anymore. "
2522			"If you need it, check 'Documentation/i2c/instantiating-devices.rst' for alternatives.\n",
2523			driver->driver.name);
2524		return 0;
2525	}
2526
2527	/* Stop here if the classes do not match */
2528	if (!(adapter->class & driver->class))
2529		return 0;
2530
2531	/* Set up a temporary client to help detect callback */
2532	temp_client = kzalloc(sizeof(*temp_client), GFP_KERNEL);
2533	if (!temp_client)
2534		return -ENOMEM;
2535
2536	temp_client->adapter = adapter;
2537
2538	for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
2539		dev_dbg(&adapter->dev,
2540			"found normal entry for adapter %d, addr 0x%02x\n",
2541			i2c_adapter_id(adapter), address_list[i]);
2542		temp_client->addr = address_list[i];
2543		err = i2c_detect_address(temp_client, driver);
2544		if (unlikely(err))
2545			break;
2546	}
2547
2548	kfree(temp_client);
2549
2550	return err;
2551}
2552
2553int i2c_probe_func_quick_read(struct i2c_adapter *adap, unsigned short addr)
2554{
2555	return i2c_smbus_xfer(adap, addr, 0, I2C_SMBUS_READ, 0,
2556			      I2C_SMBUS_QUICK, NULL) >= 0;
2557}
2558EXPORT_SYMBOL_GPL(i2c_probe_func_quick_read);
2559
2560struct i2c_client *
2561i2c_new_scanned_device(struct i2c_adapter *adap,
2562		       struct i2c_board_info *info,
2563		       unsigned short const *addr_list,
2564		       int (*probe)(struct i2c_adapter *adap, unsigned short addr))
2565{
2566	int i;
2567
2568	if (!probe)
2569		probe = i2c_default_probe;
2570
2571	for (i = 0; addr_list[i] != I2C_CLIENT_END; i++) {
2572		/* Check address validity */
2573		if (i2c_check_7bit_addr_validity_strict(addr_list[i]) < 0) {
2574			dev_warn(&adap->dev, "Invalid 7-bit address 0x%02x\n",
2575				 addr_list[i]);
2576			continue;
2577		}
2578
2579		/* Check address availability (7 bit, no need to encode flags) */
2580		if (i2c_check_addr_busy(adap, addr_list[i])) {
2581			dev_dbg(&adap->dev,
2582				"Address 0x%02x already in use, not probing\n",
2583				addr_list[i]);
2584			continue;
2585		}
2586
2587		/* Test address responsiveness */
2588		if (probe(adap, addr_list[i]))
2589			break;
2590	}
2591
2592	if (addr_list[i] == I2C_CLIENT_END) {
2593		dev_dbg(&adap->dev, "Probing failed, no device found\n");
2594		return ERR_PTR(-ENODEV);
2595	}
2596
2597	info->addr = addr_list[i];
2598	return i2c_new_client_device(adap, info);
2599}
2600EXPORT_SYMBOL_GPL(i2c_new_scanned_device);
2601
2602struct i2c_adapter *i2c_get_adapter(int nr)
2603{
2604	struct i2c_adapter *adapter;
2605
2606	mutex_lock(&core_lock);
2607	adapter = idr_find(&i2c_adapter_idr, nr);
2608	if (!adapter)
2609		goto exit;
2610
2611	if (try_module_get(adapter->owner))
2612		get_device(&adapter->dev);
2613	else
2614		adapter = NULL;
2615
2616 exit:
2617	mutex_unlock(&core_lock);
2618	return adapter;
2619}
2620EXPORT_SYMBOL(i2c_get_adapter);
2621
2622void i2c_put_adapter(struct i2c_adapter *adap)
2623{
2624	if (!adap)
2625		return;
2626
2627	module_put(adap->owner);
2628	/* Should be last, otherwise we risk use-after-free with 'adap' */
2629	put_device(&adap->dev);
2630}
2631EXPORT_SYMBOL(i2c_put_adapter);
2632
2633/**
2634 * i2c_get_dma_safe_msg_buf() - get a DMA safe buffer for the given i2c_msg
2635 * @msg: the message to be checked
2636 * @threshold: the minimum number of bytes for which using DMA makes sense.
2637 *	       Should at least be 1.
2638 *
2639 * Return: NULL if a DMA safe buffer was not obtained. Use msg->buf with PIO.
2640 *	   Or a valid pointer to be used with DMA. After use, release it by
2641 *	   calling i2c_put_dma_safe_msg_buf().
2642 *
2643 * This function must only be called from process context!
2644 */
2645u8 *i2c_get_dma_safe_msg_buf(struct i2c_msg *msg, unsigned int threshold)
2646{
2647	/* also skip 0-length msgs for bogus thresholds of 0 */
2648	if (!threshold)
2649		pr_debug("DMA buffer for addr=0x%02x with length 0 is bogus\n",
2650			 msg->addr);
2651	if (msg->len < threshold || msg->len == 0)
2652		return NULL;
2653
2654	if (msg->flags & I2C_M_DMA_SAFE)
2655		return msg->buf;
2656
2657	pr_debug("using bounce buffer for addr=0x%02x, len=%d\n",
2658		 msg->addr, msg->len);
2659
2660	if (msg->flags & I2C_M_RD)
2661		return kzalloc(msg->len, GFP_KERNEL);
2662	else
2663		return kmemdup(msg->buf, msg->len, GFP_KERNEL);
2664}
2665EXPORT_SYMBOL_GPL(i2c_get_dma_safe_msg_buf);
2666
2667/**
2668 * i2c_put_dma_safe_msg_buf - release DMA safe buffer and sync with i2c_msg
2669 * @buf: the buffer obtained from i2c_get_dma_safe_msg_buf(). May be NULL.
2670 * @msg: the message which the buffer corresponds to
2671 * @xferred: bool saying if the message was transferred
2672 */
2673void i2c_put_dma_safe_msg_buf(u8 *buf, struct i2c_msg *msg, bool xferred)
2674{
2675	if (!buf || buf == msg->buf)
2676		return;
2677
2678	if (xferred && msg->flags & I2C_M_RD)
2679		memcpy(msg->buf, buf, msg->len);
2680
2681	kfree(buf);
2682}
2683EXPORT_SYMBOL_GPL(i2c_put_dma_safe_msg_buf);
2684
2685MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
2686MODULE_DESCRIPTION("I2C-Bus main module");
2687MODULE_LICENSE("GPL");