include/linux/i2c.h

   1 /* ------------------------------------------------------------------------- */
   2 /*                                                                           */
   3 /* i2c.h - definitions for the i2c-bus interface                             */
   4 /*                                                                           */
   5 /* ------------------------------------------------------------------------- */
   6 /*   Copyright (C) 1995-2000 Simon G. Vogl
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
  21     MA 02110-1301 USA.                                                       */
  22 /* ------------------------------------------------------------------------- */
  23
  24 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
  25    Frodo Looijaard <frodol@dds.nl> */
  26 #ifndef _LINUX_I2C_H
  27 #define _LINUX_I2C_H
  28
  29 #include <linux/mod_devicetable.h>
  30 #include <linux/device.h>       /* for struct device */
  31 #include <linux/sched.h>        /* for completion */
  32 #include <linux/mutex.h>
  33 #include <linux/of.h>           /* for struct device_node */
  34 #include <linux/swab.h>         /* for swab16 */
  35 #include <uapi/linux/i2c.h>
  36
  37 extern struct bus_type i2c_bus_type;
  38 extern struct device_type i2c_adapter_type;
  39
  40 /* --- General options ------------------------------------------------ */
  41
  42 struct i2c_msg;
  43 struct i2c_algorithm;
  44 struct i2c_adapter;
  45 struct i2c_client;
  46 struct i2c_driver;
  47 union i2c_smbus_data;
  48 struct i2c_board_info;
  49 enum i2c_slave_event;
  50 typedef int (*i2c_slave_cb_t)(struct i2c_client *, enum i2c_slave_event, u8 *);
  51
  52 struct module;
  53
  54 #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
  55 /*
  56  * The master routines are the ones normally used to transmit data to devices
  57  * on a bus (or read from them). Apart from two basic transfer functions to
  58  * transmit one message at a time, a more complex version can be used to
  59  * transmit an arbitrary number of messages without interruption.
  60  * @count must be be less than 64k since msg.len is u16.
  61  */
  62 extern int i2c_master_send(const struct i2c_client *client, const char *buf,
  63                            int count);
  64 extern int i2c_master_recv(const struct i2c_client *client, char *buf,
  65                            int count);
  66
  67 /* Transfer num messages.
  68  */
  69 extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
  70                         int num);
  71 /* Unlocked flavor */
  72 extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
  73                           int num);
  74
  75 /* This is the very generalized SMBus access routine. You probably do not
  76    want to use this, though; one of the functions below may be much easier,
  77    and probably just as fast.
  78    Note that we use i2c_adapter here, because you do not need a specific
  79    smbus adapter to call this function. */
  80 extern s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
  81                           unsigned short flags, char read_write, u8 command,
  82                           int size, union i2c_smbus_data *data);
  83
  84 /* Now follow the 'nice' access routines. These also document the calling
  85    conventions of i2c_smbus_xfer. */
  86
  87 extern s32 i2c_smbus_read_byte(const struct i2c_client *client);
  88 extern s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value);
  89 extern s32 i2c_smbus_read_byte_data(const struct i2c_client *client,
  90                                     u8 command);
  91 extern s32 i2c_smbus_write_byte_data(const struct i2c_client *client,
  92                                      u8 command, u8 value);
  93 extern s32 i2c_smbus_read_word_data(const struct i2c_client *client,
  94                                     u8 command);
  95 extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,
  96                                      u8 command, u16 value);
  97
  98 static inline s32
  99 i2c_smbus_read_word_swapped(const struct i2c_client *client, u8 command)
 100 {
 101         s32 value = i2c_smbus_read_word_data(client, command);
 102
 103         return (value < 0) ? value : swab16(value);
 104 }
 105
 106 static inline s32
 107 i2c_smbus_write_word_swapped(const struct i2c_client *client,
 108                              u8 command, u16 value)
 109 {
 110         return i2c_smbus_write_word_data(client, command, swab16(value));
 111 }
 112
 113 /* Returns the number of read bytes */
 114 extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,
 115                                      u8 command, u8 *values);
 116 extern s32 i2c_smbus_write_block_data(const struct i2c_client *client,
 117                                       u8 command, u8 length, const u8 *values);
 118 /* Returns the number of read bytes */
 119 extern s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client,
 120                                          u8 command, u8 length, u8 *values);
 121 extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
 122                                           u8 command, u8 length,
 123                                           const u8 *values);
 124 #endif /* I2C */
 125
 126 /**
 127  * struct i2c_driver - represent an I2C device driver
 128  * @class: What kind of i2c device we instantiate (for detect)
 129  * @attach_adapter: Callback for bus addition (deprecated)
 130  * @probe: Callback for device binding
 131  * @remove: Callback for device unbinding
 132  * @shutdown: Callback for device shutdown
 133  * @suspend: Callback for device suspend
 134  * @resume: Callback for device resume
 135  * @alert: Alert callback, for example for the SMBus alert protocol
 136  * @command: Callback for bus-wide signaling (optional)
 137  * @driver: Device driver model driver
 138  * @id_table: List of I2C devices supported by this driver
 139  * @detect: Callback for device detection
 140  * @address_list: The I2C addresses to probe (for detect)
 141  * @clients: List of detected clients we created (for i2c-core use only)
 142  *
 143  * The driver.owner field should be set to the module owner of this driver.
 144  * The driver.name field should be set to the name of this driver.
 145  *
 146  * For automatic device detection, both @detect and @address_list must
 147  * be defined. @class should also be set, otherwise only devices forced
 148  * with module parameters will be created. The detect function must
 149  * fill at least the name field of the i2c_board_info structure it is
 150  * handed upon successful detection, and possibly also the flags field.
 151  *
 152  * If @detect is missing, the driver will still work fine for enumerated
 153  * devices. Detected devices simply won't be supported. This is expected
 154  * for the many I2C/SMBus devices which can't be detected reliably, and
 155  * the ones which can always be enumerated in practice.
 156  *
 157  * The i2c_client structure which is handed to the @detect callback is
 158  * not a real i2c_client. It is initialized just enough so that you can
 159  * call i2c_smbus_read_byte_data and friends on it. Don't do anything
 160  * else with it. In particular, calling dev_dbg and friends on it is
 161  * not allowed.
 162  */
 163 struct i2c_driver {
 164         unsigned int class;
 165
 166         /* Notifies the driver that a new bus has appeared. You should avoid
 167          * using this, it will be removed in a near future.
 168          */
 169         int (*attach_adapter)(struct i2c_adapter *) __deprecated;
 170
 171         /* Standard driver model interfaces */
 172         int (*probe)(struct i2c_client *, const struct i2c_device_id *);
 173         int (*remove)(struct i2c_client *);
 174
 175         /* driver model interfaces that don't relate to enumeration  */
 176         void (*shutdown)(struct i2c_client *);
 177         int (*suspend)(struct i2c_client *, pm_message_t mesg);
 178         int (*resume)(struct i2c_client *);
 179
 180         /* Alert callback, for example for the SMBus alert protocol.
 181          * The format and meaning of the data value depends on the protocol.
 182          * For the SMBus alert protocol, there is a single bit of data passed
 183          * as the alert response's low bit ("event flag").
 184          */
 185         void (*alert)(struct i2c_client *, unsigned int data);
 186
 187         /* a ioctl like command that can be used to perform specific functions
 188          * with the device.
 189          */
 190         int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);
 191
 192         struct device_driver driver;
 193         const struct i2c_device_id *id_table;
 194
 195         /* Device detection callback for automatic device creation */
 196         int (*detect)(struct i2c_client *, struct i2c_board_info *);
 197         const unsigned short *address_list;
 198         struct list_head clients;
 199 };
 200 #define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)
 201
 202 /**
 203  * struct i2c_client - represent an I2C slave device
 204  * @flags: I2C_CLIENT_TEN indicates the device uses a ten bit chip address;
 205  *      I2C_CLIENT_PEC indicates it uses SMBus Packet Error Checking
 206  * @addr: Address used on the I2C bus connected to the parent adapter.
 207  * @name: Indicates the type of the device, usually a chip name that's
 208  *      generic enough to hide second-sourcing and compatible revisions.
 209  * @adapter: manages the bus segment hosting this I2C device
 210  * @dev: Driver model device node for the slave.
 211  * @irq: indicates the IRQ generated by this device (if any)
 212  * @detected: member of an i2c_driver.clients list or i2c-core's
 213  *      userspace_devices list
 214  * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
 215  *      calls it to pass on slave events to the slave driver.
 216  *
 217  * An i2c_client identifies a single device (i.e. chip) connected to an
 218  * i2c bus. The behaviour exposed to Linux is defined by the driver
 219  * managing the device.
 220  */
 221 struct i2c_client {
 222         unsigned short flags;           /* div., see below              */
 223         unsigned short addr;            /* chip address - NOTE: 7bit    */
 224                                         /* addresses are stored in the  */
 225                                         /* _LOWER_ 7 bits               */
 226         char name[I2C_NAME_SIZE];
 227         struct i2c_adapter *adapter;    /* the adapter we sit on        */
 228         struct device dev;              /* the device structure         */
 229         int irq;                        /* irq issued by device         */
 230         struct list_head detected;
 231 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 232         i2c_slave_cb_t slave_cb;        /* callback for slave mode      */
 233 #endif
 234 };
 235 #define to_i2c_client(d) container_of(d, struct i2c_client, dev)
 236
 237 extern struct i2c_client *i2c_verify_client(struct device *dev);
 238 extern struct i2c_adapter *i2c_verify_adapter(struct device *dev);
 239
 240 static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
 241 {
 242         struct device * const dev = container_of(kobj, struct device, kobj);
 243         return to_i2c_client(dev);
 244 }
 245
 246 static inline void *i2c_get_clientdata(const struct i2c_client *dev)
 247 {
 248         return dev_get_drvdata(&dev->dev);
 249 }
 250
 251 static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
 252 {
 253         dev_set_drvdata(&dev->dev, data);
 254 }
 255
 256 /* I2C slave support */
 257
 258 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 259 enum i2c_slave_event {
 260         I2C_SLAVE_REQ_READ_START,
 261         I2C_SLAVE_REQ_READ_END,
 262         I2C_SLAVE_REQ_WRITE_START,
 263         I2C_SLAVE_REQ_WRITE_END,
 264         I2C_SLAVE_STOP,
 265 };
 266
 267 extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
 268 extern int i2c_slave_unregister(struct i2c_client *client);
 269
 270 static inline int i2c_slave_event(struct i2c_client *client,
 271                                   enum i2c_slave_event event, u8 *val)
 272 {
 273         return client->slave_cb(client, event, val);
 274 }
 275 #endif
 276
 277 /**
 278  * struct i2c_board_info - template for device creation
 279  * @type: chip type, to initialize i2c_client.name
 280  * @flags: to initialize i2c_client.flags
 281  * @addr: stored in i2c_client.addr
 282  * @platform_data: stored in i2c_client.dev.platform_data
 283  * @archdata: copied into i2c_client.dev.archdata
 284  * @of_node: pointer to OpenFirmware device node
 285  * @acpi_node: ACPI device node
 286  * @irq: stored in i2c_client.irq
 287  *
 288  * I2C doesn't actually support hardware probing, although controllers and
 289  * devices may be able to use I2C_SMBUS_QUICK to tell whether or not there's
 290  * a device at a given address.  Drivers commonly need more information than
 291  * that, such as chip type, configuration, associated IRQ, and so on.
 292  *
 293  * i2c_board_info is used to build tables of information listing I2C devices
 294  * that are present.  This information is used to grow the driver model tree.
 295  * For mainboards this is done statically using i2c_register_board_info();
 296  * bus numbers identify adapters that aren't yet available.  For add-on boards,
 297  * i2c_new_device() does this dynamically with the adapter already known.
 298  */
 299 struct i2c_board_info {
 300         char            type[I2C_NAME_SIZE];
 301         unsigned short  flags;
 302         unsigned short  addr;
 303         void            *platform_data;
 304         struct dev_archdata     *archdata;
 305         struct device_node *of_node;
 306         struct acpi_dev_node acpi_node;
 307         int             irq;
 308 };
 309
 310 /**
 311  * I2C_BOARD_INFO - macro used to list an i2c device and its address
 312  * @dev_type: identifies the device type
 313  * @dev_addr: the device's address on the bus.
 314  *
 315  * This macro initializes essential fields of a struct i2c_board_info,
 316  * declaring what has been provided on a particular board.  Optional
 317  * fields (such as associated irq, or device-specific platform_data)
 318  * are provided using conventional syntax.
 319  */
 320 #define I2C_BOARD_INFO(dev_type, dev_addr) \
 321         .type = dev_type, .addr = (dev_addr)
 322
 323
 324 #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
 325 /* Add-on boards should register/unregister their devices; e.g. a board
 326  * with integrated I2C, a config eeprom, sensors, and a codec that's
 327  * used in conjunction with the primary hardware.
 328  */
 329 extern struct i2c_client *
 330 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);
 331
 332 /* If you don't know the exact address of an I2C device, use this variant
 333  * instead, which can probe for device presence in a list of possible
 334  * addresses. The "probe" callback function is optional. If it is provided,
 335  * it must return 1 on successful probe, 0 otherwise. If it is not provided,
 336  * a default probing method is used.
 337  */
 338 extern struct i2c_client *
 339 i2c_new_probed_device(struct i2c_adapter *adap,
 340                       struct i2c_board_info *info,
 341                       unsigned short const *addr_list,
 342                       int (*probe)(struct i2c_adapter *, unsigned short addr));
 343
 344 /* Common custom probe functions */
 345 extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);
 346
 347 /* For devices that use several addresses, use i2c_new_dummy() to make
 348  * client handles for the extra addresses.
 349  */
 350 extern struct i2c_client *
 351 i2c_new_dummy(struct i2c_adapter *adap, u16 address);
 352
 353 extern void i2c_unregister_device(struct i2c_client *);
 354 #endif /* I2C */
 355
 356 /* Mainboard arch_initcall() code should register all its I2C devices.
 357  * This is done at arch_initcall time, before declaring any i2c adapters.
 358  * Modules for add-on boards must use other calls.
 359  */
 360 #ifdef CONFIG_I2C_BOARDINFO
 361 extern int
 362 i2c_register_board_info(int busnum, struct i2c_board_info const *info,
 363                         unsigned n);
 364 #else
 365 static inline int
 366 i2c_register_board_info(int busnum, struct i2c_board_info const *info,
 367                         unsigned n)
 368 {
 369         return 0;
 370 }
 371 #endif /* I2C_BOARDINFO */
 372
 373 /**
 374  * struct i2c_algorithm - represent I2C transfer method
 375  * @master_xfer: Issue a set of i2c transactions to the given I2C adapter
 376  *   defined by the msgs array, with num messages available to transfer via
 377  *   the adapter specified by adap.
 378  * @smbus_xfer: Issue smbus transactions to the given I2C adapter. If this
 379  *   is not present, then the bus layer will try and convert the SMBus calls
 380  *   into I2C transfers instead.
 381  * @functionality: Return the flags that this algorithm/adapter pair supports
 382  *   from the I2C_FUNC_* flags.
 383  * @reg_slave: Register given client to I2C slave mode of this adapter
 384  * @unreg_slave: Unregister given client from I2C slave mode of this adapter
 385  *
 386  * The following structs are for those who like to implement new bus drivers:
 387  * i2c_algorithm is the interface to a class of hardware solutions which can
 388  * be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584
 389  * to name two of the most common.
 390  *
 391  * The return codes from the @master_xfer field should indicate the type of
 392  * error code that occurred during the transfer, as documented in the kernel
 393  * Documentation file Documentation/i2c/fault-codes.
 394  */
 395 struct i2c_algorithm {
 396         /* If an adapter algorithm can't do I2C-level access, set master_xfer
 397            to NULL. If an adapter algorithm can do SMBus access, set
 398            smbus_xfer. If set to NULL, the SMBus protocol is simulated
 399            using common I2C messages */
 400         /* master_xfer should return the number of messages successfully
 401            processed, or a negative value on error */
 402         int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs,
 403                            int num);
 404         int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,
 405                            unsigned short flags, char read_write,
 406                            u8 command, int size, union i2c_smbus_data *data);
 407
 408         /* To determine what the adapter supports */
 409         u32 (*functionality) (struct i2c_adapter *);
 410
 411 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 412         int (*reg_slave)(struct i2c_client *client);
 413         int (*unreg_slave)(struct i2c_client *client);
 414 #endif
 415 };
 416
 417 /**
 418  * struct i2c_bus_recovery_info - I2C bus recovery information
 419  * @recover_bus: Recover routine. Either pass driver's recover_bus() routine, or
 420  *      i2c_generic_scl_recovery() or i2c_generic_gpio_recovery().
 421  * @get_scl: This gets current value of SCL line. Mandatory for generic SCL
 422  *      recovery. Used internally for generic GPIO recovery.
 423  * @set_scl: This sets/clears SCL line. Mandatory for generic SCL recovery. Used
 424  *      internally for generic GPIO recovery.
 425  * @get_sda: This gets current value of SDA line. Optional for generic SCL
 426  *      recovery. Used internally, if sda_gpio is a valid GPIO, for generic GPIO
 427  *      recovery.
 428  * @prepare_recovery: This will be called before starting recovery. Platform may
 429  *      configure padmux here for SDA/SCL line or something else they want.
 430  * @unprepare_recovery: This will be called after completing recovery. Platform
 431  *      may configure padmux here for SDA/SCL line or something else they want.
 432  * @scl_gpio: gpio number of the SCL line. Only required for GPIO recovery.
 433  * @sda_gpio: gpio number of the SDA line. Only required for GPIO recovery.
 434  */
 435 struct i2c_bus_recovery_info {
 436         int (*recover_bus)(struct i2c_adapter *);
 437
 438         int (*get_scl)(struct i2c_adapter *);
 439         void (*set_scl)(struct i2c_adapter *, int val);
 440         int (*get_sda)(struct i2c_adapter *);
 441
 442         void (*prepare_recovery)(struct i2c_bus_recovery_info *bri);
 443         void (*unprepare_recovery)(struct i2c_bus_recovery_info *bri);
 444
 445         /* gpio recovery */
 446         int scl_gpio;
 447         int sda_gpio;
 448 };
 449
 450 int i2c_recover_bus(struct i2c_adapter *adap);
 451
 452 /* Generic recovery routines */
 453 int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
 454 int i2c_generic_scl_recovery(struct i2c_adapter *adap);
 455
 456 /*
 457  * i2c_adapter is the structure used to identify a physical i2c bus along
 458  * with the access algorithms necessary to access it.
 459  */
 460 struct i2c_adapter {
 461         struct module *owner;
 462         unsigned int class;               /* classes to allow probing for */
 463         const struct i2c_algorithm *algo; /* the algorithm to access the bus */
 464         void *algo_data;
 465
 466         /* data fields that are valid for all devices   */
 467         struct rt_mutex bus_lock;
 468
 469         int timeout;                    /* in jiffies */
 470         int retries;
 471         struct device dev;              /* the adapter device */
 472
 473         int nr;
 474         char name[48];
 475         struct completion dev_released;
 476
 477         struct mutex userspace_clients_lock;
 478         struct list_head userspace_clients;
 479
 480         struct i2c_bus_recovery_info *bus_recovery_info;
 481 };
 482 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
 483
 484 static inline void *i2c_get_adapdata(const struct i2c_adapter *dev)
 485 {
 486         return dev_get_drvdata(&dev->dev);
 487 }
 488
 489 static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
 490 {
 491         dev_set_drvdata(&dev->dev, data);
 492 }
 493
 494 static inline struct i2c_adapter *
 495 i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
 496 {
 497 #if IS_ENABLED(CONFIG_I2C_MUX)
 498         struct device *parent = adapter->dev.parent;
 499
 500         if (parent != NULL && parent->type == &i2c_adapter_type)
 501                 return to_i2c_adapter(parent);
 502         else
 503 #endif
 504                 return NULL;
 505 }
 506
 507 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *));
 508
 509 /* Adapter locking functions, exported for shared pin cases */
 510 void i2c_lock_adapter(struct i2c_adapter *);
 511 void i2c_unlock_adapter(struct i2c_adapter *);
 512
 513 /*flags for the client struct: */
 514 #define I2C_CLIENT_PEC  0x04            /* Use Packet Error Checking */
 515 #define I2C_CLIENT_TEN  0x10            /* we have a ten bit chip address */
 516                                         /* Must equal I2C_M_TEN below */
 517 #define I2C_CLIENT_WAKE 0x80            /* for board_info; true iff can wake */
 518 #define I2C_CLIENT_SCCB 0x9000          /* Use Omnivision SCCB protocol */
 519                                         /* Must match I2C_M_STOP|IGNORE_NAK */
 520
 521 /* i2c adapter classes (bitmask) */
 522 #define I2C_CLASS_HWMON         (1<<0)  /* lm_sensors, ... */
 523 #define I2C_CLASS_DDC           (1<<3)  /* DDC bus on graphics adapters */
 524 #define I2C_CLASS_SPD           (1<<7)  /* Memory modules */
 525 #define I2C_CLASS_DEPRECATED    (1<<8)  /* Warn users that adapter will stop using classes */
 526
 527 /* Internal numbers to terminate lists */
 528 #define I2C_CLIENT_END          0xfffeU
 529
 530 /* Construct an I2C_CLIENT_END-terminated array of i2c addresses */
 531 #define I2C_ADDRS(addr, addrs...) \
 532         ((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })
 533
 534
 535 /* ----- functions exported by i2c.o */
 536
 537 /* administration...
 538  */
 539 #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
 540 extern int i2c_add_adapter(struct i2c_adapter *);
 541 extern void i2c_del_adapter(struct i2c_adapter *);
 542 extern int i2c_add_numbered_adapter(struct i2c_adapter *);
 543
 544 extern int i2c_register_driver(struct module *, struct i2c_driver *);
 545 extern void i2c_del_driver(struct i2c_driver *);
 546
 547 /* use a define to avoid include chaining to get THIS_MODULE */
 548 #define i2c_add_driver(driver) \
 549         i2c_register_driver(THIS_MODULE, driver)
 550
 551 extern struct i2c_client *i2c_use_client(struct i2c_client *client);
 552 extern void i2c_release_client(struct i2c_client *client);
 553
 554 /* call the i2c_client->command() of all attached clients with
 555  * the given arguments */
 556 extern void i2c_clients_command(struct i2c_adapter *adap,
 557                                 unsigned int cmd, void *arg);
 558
 559 extern struct i2c_adapter *i2c_get_adapter(int nr);
 560 extern void i2c_put_adapter(struct i2c_adapter *adap);
 561
 562
 563 /* Return the functionality mask */
 564 static inline u32 i2c_get_functionality(struct i2c_adapter *adap)
 565 {
 566         return adap->algo->functionality(adap);
 567 }
 568
 569 /* Return 1 if adapter supports everything we need, 0 if not. */
 570 static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)
 571 {
 572         return (func & i2c_get_functionality(adap)) == func;
 573 }
 574
 575 /* Return the adapter number for a specific adapter */
 576 static inline int i2c_adapter_id(struct i2c_adapter *adap)
 577 {
 578         return adap->nr;
 579 }
 580
 581 /**
 582  * module_i2c_driver() - Helper macro for registering a I2C driver
 583  * @__i2c_driver: i2c_driver struct
 584  *
 585  * Helper macro for I2C drivers which do not do anything special in module
 586  * init/exit. This eliminates a lot of boilerplate. Each module may only
 587  * use this macro once, and calling it replaces module_init() and module_exit()
 588  */
 589 #define module_i2c_driver(__i2c_driver) \
 590         module_driver(__i2c_driver, i2c_add_driver, \
 591                         i2c_del_driver)
 592
 593 #endif /* I2C */
 594
 595 #if IS_ENABLED(CONFIG_OF)
 596 /* must call put_device() when done with returned i2c_client device */
 597 extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
 598
 599 /* must call put_device() when done with returned i2c_adapter device */
 600 extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
 601
 602 #else
 603
 604 static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
 605 {
 606         return NULL;
 607 }
 608
 609 static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
 610 {
 611         return NULL;
 612 }
 613 #endif /* CONFIG_OF */
 614
 615 #endif /* _LINUX_I2C_H */