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         i2c_slave_cb_t slave_cb;        /* callback for slave mode      */
 232 };
 233 #define to_i2c_client(d) container_of(d, struct i2c_client, dev)
 234
 235 extern struct i2c_client *i2c_verify_client(struct device *dev);
 236 extern struct i2c_adapter *i2c_verify_adapter(struct device *dev);
 237
 238 static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
 239 {
 240         struct device * const dev = container_of(kobj, struct device, kobj);
 241         return to_i2c_client(dev);
 242 }
 243
 244 static inline void *i2c_get_clientdata(const struct i2c_client *dev)
 245 {
 246         return dev_get_drvdata(&dev->dev);
 247 }
 248
 249 static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
 250 {
 251         dev_set_drvdata(&dev->dev, data);
 252 }
 253
 254 /* I2C slave support */
 255
 256 enum i2c_slave_event {
 257         I2C_SLAVE_REQ_READ_START,
 258         I2C_SLAVE_REQ_READ_END,
 259         I2C_SLAVE_REQ_WRITE_START,
 260         I2C_SLAVE_REQ_WRITE_END,
 261         I2C_SLAVE_STOP,
 262 };
 263
 264 extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
 265 extern int i2c_slave_unregister(struct i2c_client *client);
 266
 267 static inline int i2c_slave_event(struct i2c_client *client,
 268                                   enum i2c_slave_event event, u8 *val)
 269 {
 270         return client->slave_cb(client, event, val);
 271 }
 272
 273 /**
 274  * struct i2c_board_info - template for device creation
 275  * @type: chip type, to initialize i2c_client.name
 276  * @flags: to initialize i2c_client.flags
 277  * @addr: stored in i2c_client.addr
 278  * @platform_data: stored in i2c_client.dev.platform_data
 279  * @archdata: copied into i2c_client.dev.archdata
 280  * @of_node: pointer to OpenFirmware device node
 281  * @acpi_node: ACPI device node
 282  * @irq: stored in i2c_client.irq
 283  *
 284  * I2C doesn't actually support hardware probing, although controllers and
 285  * devices may be able to use I2C_SMBUS_QUICK to tell whether or not there's
 286  * a device at a given address.  Drivers commonly need more information than
 287  * that, such as chip type, configuration, associated IRQ, and so on.
 288  *
 289  * i2c_board_info is used to build tables of information listing I2C devices
 290  * that are present.  This information is used to grow the driver model tree.
 291  * For mainboards this is done statically using i2c_register_board_info();
 292  * bus numbers identify adapters that aren't yet available.  For add-on boards,
 293  * i2c_new_device() does this dynamically with the adapter already known.
 294  */
 295 struct i2c_board_info {
 296         char            type[I2C_NAME_SIZE];
 297         unsigned short  flags;
 298         unsigned short  addr;
 299         void            *platform_data;
 300         struct dev_archdata     *archdata;
 301         struct device_node *of_node;
 302         struct acpi_dev_node acpi_node;
 303         int             irq;
 304 };
 305
 306 /**
 307  * I2C_BOARD_INFO - macro used to list an i2c device and its address
 308  * @dev_type: identifies the device type
 309  * @dev_addr: the device's address on the bus.
 310  *
 311  * This macro initializes essential fields of a struct i2c_board_info,
 312  * declaring what has been provided on a particular board.  Optional
 313  * fields (such as associated irq, or device-specific platform_data)
 314  * are provided using conventional syntax.
 315  */
 316 #define I2C_BOARD_INFO(dev_type, dev_addr) \
 317         .type = dev_type, .addr = (dev_addr)
 318
 319
 320 #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
 321 /* Add-on boards should register/unregister their devices; e.g. a board
 322  * with integrated I2C, a config eeprom, sensors, and a codec that's
 323  * used in conjunction with the primary hardware.
 324  */
 325 extern struct i2c_client *
 326 i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);
 327
 328 /* If you don't know the exact address of an I2C device, use this variant
 329  * instead, which can probe for device presence in a list of possible
 330  * addresses. The "probe" callback function is optional. If it is provided,
 331  * it must return 1 on successful probe, 0 otherwise. If it is not provided,
 332  * a default probing method is used.
 333  */
 334 extern struct i2c_client *
 335 i2c_new_probed_device(struct i2c_adapter *adap,
 336                       struct i2c_board_info *info,
 337                       unsigned short const *addr_list,
 338                       int (*probe)(struct i2c_adapter *, unsigned short addr));
 339
 340 /* Common custom probe functions */
 341 extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);
 342
 343 /* For devices that use several addresses, use i2c_new_dummy() to make
 344  * client handles for the extra addresses.
 345  */
 346 extern struct i2c_client *
 347 i2c_new_dummy(struct i2c_adapter *adap, u16 address);
 348
 349 extern void i2c_unregister_device(struct i2c_client *);
 350 #endif /* I2C */
 351
 352 /* Mainboard arch_initcall() code should register all its I2C devices.
 353  * This is done at arch_initcall time, before declaring any i2c adapters.
 354  * Modules for add-on boards must use other calls.
 355  */
 356 #ifdef CONFIG_I2C_BOARDINFO
 357 extern int
 358 i2c_register_board_info(int busnum, struct i2c_board_info const *info,
 359                         unsigned n);
 360 #else
 361 static inline int
 362 i2c_register_board_info(int busnum, struct i2c_board_info const *info,
 363                         unsigned n)
 364 {
 365         return 0;
 366 }
 367 #endif /* I2C_BOARDINFO */
 368
 369 /**
 370  * struct i2c_algorithm - represent I2C transfer method
 371  * @master_xfer: Issue a set of i2c transactions to the given I2C adapter
 372  *   defined by the msgs array, with num messages available to transfer via
 373  *   the adapter specified by adap.
 374  * @smbus_xfer: Issue smbus transactions to the given I2C adapter. If this
 375  *   is not present, then the bus layer will try and convert the SMBus calls
 376  *   into I2C transfers instead.
 377  * @functionality: Return the flags that this algorithm/adapter pair supports
 378  *   from the I2C_FUNC_* flags.
 379  * @reg_slave: Register given client to I2C slave mode of this adapter
 380  * @unreg_slave: Unregister given client from I2C slave mode of this adapter
 381  *
 382  * The following structs are for those who like to implement new bus drivers:
 383  * i2c_algorithm is the interface to a class of hardware solutions which can
 384  * be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584
 385  * to name two of the most common.
 386  *
 387  * The return codes from the @master_xfer field should indicate the type of
 388  * error code that occurred during the transfer, as documented in the kernel
 389  * Documentation file Documentation/i2c/fault-codes.
 390  */
 391 struct i2c_algorithm {
 392         /* If an adapter algorithm can't do I2C-level access, set master_xfer
 393            to NULL. If an adapter algorithm can do SMBus access, set
 394            smbus_xfer. If set to NULL, the SMBus protocol is simulated
 395            using common I2C messages */
 396         /* master_xfer should return the number of messages successfully
 397            processed, or a negative value on error */
 398         int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs,
 399                            int num);
 400         int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,
 401                            unsigned short flags, char read_write,
 402                            u8 command, int size, union i2c_smbus_data *data);
 403
 404         /* To determine what the adapter supports */
 405         u32 (*functionality) (struct i2c_adapter *);
 406
 407         int (*reg_slave)(struct i2c_client *client);
 408         int (*unreg_slave)(struct i2c_client *client);
 409 };
 410
 411 /**
 412  * struct i2c_bus_recovery_info - I2C bus recovery information
 413  * @recover_bus: Recover routine. Either pass driver's recover_bus() routine, or
 414  *      i2c_generic_scl_recovery() or i2c_generic_gpio_recovery().
 415  * @get_scl: This gets current value of SCL line. Mandatory for generic SCL
 416  *      recovery. Used internally for generic GPIO recovery.
 417  * @set_scl: This sets/clears SCL line. Mandatory for generic SCL recovery. Used
 418  *      internally for generic GPIO recovery.
 419  * @get_sda: This gets current value of SDA line. Optional for generic SCL
 420  *      recovery. Used internally, if sda_gpio is a valid GPIO, for generic GPIO
 421  *      recovery.
 422  * @prepare_recovery: This will be called before starting recovery. Platform may
 423  *      configure padmux here for SDA/SCL line or something else they want.
 424  * @unprepare_recovery: This will be called after completing recovery. Platform
 425  *      may configure padmux here for SDA/SCL line or something else they want.
 426  * @scl_gpio: gpio number of the SCL line. Only required for GPIO recovery.
 427  * @sda_gpio: gpio number of the SDA line. Only required for GPIO recovery.
 428  */
 429 struct i2c_bus_recovery_info {
 430         int (*recover_bus)(struct i2c_adapter *);
 431
 432         int (*get_scl)(struct i2c_adapter *);
 433         void (*set_scl)(struct i2c_adapter *, int val);
 434         int (*get_sda)(struct i2c_adapter *);
 435
 436         void (*prepare_recovery)(struct i2c_bus_recovery_info *bri);
 437         void (*unprepare_recovery)(struct i2c_bus_recovery_info *bri);
 438
 439         /* gpio recovery */
 440         int scl_gpio;
 441         int sda_gpio;
 442 };
 443
 444 int i2c_recover_bus(struct i2c_adapter *adap);
 445
 446 /* Generic recovery routines */
 447 int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
 448 int i2c_generic_scl_recovery(struct i2c_adapter *adap);
 449
 450 /*
 451  * i2c_adapter is the structure used to identify a physical i2c bus along
 452  * with the access algorithms necessary to access it.
 453  */
 454 struct i2c_adapter {
 455         struct module *owner;
 456         unsigned int class;               /* classes to allow probing for */
 457         const struct i2c_algorithm *algo; /* the algorithm to access the bus */
 458         void *algo_data;
 459
 460         /* data fields that are valid for all devices   */
 461         struct rt_mutex bus_lock;
 462
 463         int timeout;                    /* in jiffies */
 464         int retries;
 465         struct device dev;              /* the adapter device */
 466
 467         int nr;
 468         char name[48];
 469         struct completion dev_released;
 470
 471         struct mutex userspace_clients_lock;
 472         struct list_head userspace_clients;
 473
 474         struct i2c_bus_recovery_info *bus_recovery_info;
 475 };
 476 #define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)
 477
 478 static inline void *i2c_get_adapdata(const struct i2c_adapter *dev)
 479 {
 480         return dev_get_drvdata(&dev->dev);
 481 }
 482
 483 static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
 484 {
 485         dev_set_drvdata(&dev->dev, data);
 486 }
 487
 488 static inline struct i2c_adapter *
 489 i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
 490 {
 491 #if IS_ENABLED(CONFIG_I2C_MUX)
 492         struct device *parent = adapter->dev.parent;
 493
 494         if (parent != NULL && parent->type == &i2c_adapter_type)
 495                 return to_i2c_adapter(parent);
 496         else
 497 #endif
 498                 return NULL;
 499 }
 500
 501 int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *));
 502
 503 /* Adapter locking functions, exported for shared pin cases */
 504 void i2c_lock_adapter(struct i2c_adapter *);
 505 void i2c_unlock_adapter(struct i2c_adapter *);
 506
 507 /*flags for the client struct: */
 508 #define I2C_CLIENT_PEC  0x04            /* Use Packet Error Checking */
 509 #define I2C_CLIENT_TEN  0x10            /* we have a ten bit chip address */
 510                                         /* Must equal I2C_M_TEN below */
 511 #define I2C_CLIENT_WAKE 0x80            /* for board_info; true iff can wake */
 512 #define I2C_CLIENT_SCCB 0x9000          /* Use Omnivision SCCB protocol */
 513                                         /* Must match I2C_M_STOP|IGNORE_NAK */
 514
 515 /* i2c adapter classes (bitmask) */
 516 #define I2C_CLASS_HWMON         (1<<0)  /* lm_sensors, ... */
 517 #define I2C_CLASS_DDC           (1<<3)  /* DDC bus on graphics adapters */
 518 #define I2C_CLASS_SPD           (1<<7)  /* Memory modules */
 519 #define I2C_CLASS_DEPRECATED    (1<<8)  /* Warn users that adapter will stop using classes */
 520
 521 /* Internal numbers to terminate lists */
 522 #define I2C_CLIENT_END          0xfffeU
 523
 524 /* Construct an I2C_CLIENT_END-terminated array of i2c addresses */
 525 #define I2C_ADDRS(addr, addrs...) \
 526         ((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })
 527
 528
 529 /* ----- functions exported by i2c.o */
 530
 531 /* administration...
 532  */
 533 #if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
 534 extern int i2c_add_adapter(struct i2c_adapter *);
 535 extern void i2c_del_adapter(struct i2c_adapter *);
 536 extern int i2c_add_numbered_adapter(struct i2c_adapter *);
 537
 538 extern int i2c_register_driver(struct module *, struct i2c_driver *);
 539 extern void i2c_del_driver(struct i2c_driver *);
 540
 541 /* use a define to avoid include chaining to get THIS_MODULE */
 542 #define i2c_add_driver(driver) \
 543         i2c_register_driver(THIS_MODULE, driver)
 544
 545 extern struct i2c_client *i2c_use_client(struct i2c_client *client);
 546 extern void i2c_release_client(struct i2c_client *client);
 547
 548 /* call the i2c_client->command() of all attached clients with
 549  * the given arguments */
 550 extern void i2c_clients_command(struct i2c_adapter *adap,
 551                                 unsigned int cmd, void *arg);
 552
 553 extern struct i2c_adapter *i2c_get_adapter(int nr);
 554 extern void i2c_put_adapter(struct i2c_adapter *adap);
 555
 556
 557 /* Return the functionality mask */
 558 static inline u32 i2c_get_functionality(struct i2c_adapter *adap)
 559 {
 560         return adap->algo->functionality(adap);
 561 }
 562
 563 /* Return 1 if adapter supports everything we need, 0 if not. */
 564 static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)
 565 {
 566         return (func & i2c_get_functionality(adap)) == func;
 567 }
 568
 569 /* Return the adapter number for a specific adapter */
 570 static inline int i2c_adapter_id(struct i2c_adapter *adap)
 571 {
 572         return adap->nr;
 573 }
 574
 575 /**
 576  * module_i2c_driver() - Helper macro for registering a I2C driver
 577  * @__i2c_driver: i2c_driver struct
 578  *
 579  * Helper macro for I2C drivers which do not do anything special in module
 580  * init/exit. This eliminates a lot of boilerplate. Each module may only
 581  * use this macro once, and calling it replaces module_init() and module_exit()
 582  */
 583 #define module_i2c_driver(__i2c_driver) \
 584         module_driver(__i2c_driver, i2c_add_driver, \
 585                         i2c_del_driver)
 586
 587 #endif /* I2C */
 588
 589 #if IS_ENABLED(CONFIG_OF)
 590 /* must call put_device() when done with returned i2c_client device */
 591 extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);
 592
 593 /* must call put_device() when done with returned i2c_adapter device */
 594 extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);
 595
 596 #else
 597
 598 static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
 599 {
 600         return NULL;
 601 }
 602
 603 static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
 604 {
 605         return NULL;
 606 }
 607 #endif /* CONFIG_OF */
 608
 609 #endif /* _LINUX_I2C_H */