aboutsummaryrefslogtreecommitdiff
path: root/include/linux/i2c.h
blob: 768063baafbf5efe6c122a123b0c3f9bfe3bd050 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
/* ------------------------------------------------------------------------- */
/*									     */
/* i2c.h - definitions for the i2c-bus interface			     */
/*									     */
/* ------------------------------------------------------------------------- */
/*   Copyright (C) 1995-2000 Simon G. Vogl

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
    MA 02110-1301 USA.							     */
/* ------------------------------------------------------------------------- */

/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
   Frodo Looijaard <frodol@dds.nl> */
#ifndef _LINUX_I2C_H
#define _LINUX_I2C_H

#include <linux/mod_devicetable.h>
#include <linux/device.h>	/* for struct device */
#include <linux/sched.h>	/* for completion */
#include <linux/mutex.h>
#include <linux/of.h>		/* for struct device_node */
#include <linux/swab.h>		/* for swab16 */
#include <uapi/linux/i2c.h>

extern struct bus_type i2c_bus_type;
extern struct device_type i2c_adapter_type;

/* --- General options ------------------------------------------------	*/

struct i2c_msg;
struct i2c_algorithm;
struct i2c_adapter;
struct i2c_client;
struct i2c_driver;
union i2c_smbus_data;
struct i2c_board_info;
enum i2c_slave_event;
typedef int (*i2c_slave_cb_t)(struct i2c_client *, enum i2c_slave_event, u8 *);

struct module;

#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
/*
 * The master routines are the ones normally used to transmit data to devices
 * on a bus (or read from them). Apart from two basic transfer functions to
 * transmit one message at a time, a more complex version can be used to
 * transmit an arbitrary number of messages without interruption.
 * @count must be be less than 64k since msg.len is u16.
 */
extern int i2c_master_send(const struct i2c_client *client, const char *buf,
			   int count);
extern int i2c_master_recv(const struct i2c_client *client, char *buf,
			   int count);

/* Transfer num messages.
 */
extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
			int num);
/* Unlocked flavor */
extern int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
			  int num);

/* This is the very generalized SMBus access routine. You probably do not
   want to use this, though; one of the functions below may be much easier,
   and probably just as fast.
   Note that we use i2c_adapter here, because you do not need a specific
   smbus adapter to call this function. */
extern s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
			  unsigned short flags, char read_write, u8 command,
			  int size, union i2c_smbus_data *data);

/* Now follow the 'nice' access routines. These also document the calling
   conventions of i2c_smbus_xfer. */

extern s32 i2c_smbus_read_byte(const struct i2c_client *client);
extern s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value);
extern s32 i2c_smbus_read_byte_data(const struct i2c_client *client,
				    u8 command);
extern s32 i2c_smbus_write_byte_data(const struct i2c_client *client,
				     u8 command, u8 value);
extern s32 i2c_smbus_read_word_data(const struct i2c_client *client,
				    u8 command);
extern s32 i2c_smbus_write_word_data(const struct i2c_client *client,
				     u8 command, u16 value);

static inline s32
i2c_smbus_read_word_swapped(const struct i2c_client *client, u8 command)
{
	s32 value = i2c_smbus_read_word_data(client, command);

	return (value < 0) ? value : swab16(value);
}

static inline s32
i2c_smbus_write_word_swapped(const struct i2c_client *client,
			     u8 command, u16 value)
{
	return i2c_smbus_write_word_data(client, command, swab16(value));
}

/* Returns the number of read bytes */
extern s32 i2c_smbus_read_block_data(const struct i2c_client *client,
				     u8 command, u8 *values);
extern s32 i2c_smbus_write_block_data(const struct i2c_client *client,
				      u8 command, u8 length, const u8 *values);
/* Returns the number of read bytes */
extern s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client,
					 u8 command, u8 length, u8 *values);
extern s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client,
					  u8 command, u8 length,
					  const u8 *values);
extern s32
i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
					  u8 command, u8 length, u8 *values);
#endif /* I2C */

/**
 * struct i2c_driver - represent an I2C device driver
 * @class: What kind of i2c device we instantiate (for detect)
 * @attach_adapter: Callback for bus addition (deprecated)
 * @probe: Callback for device binding
 * @remove: Callback for device unbinding
 * @shutdown: Callback for device shutdown
 * @alert: Alert callback, for example for the SMBus alert protocol
 * @command: Callback for bus-wide signaling (optional)
 * @driver: Device driver model driver
 * @id_table: List of I2C devices supported by this driver
 * @detect: Callback for device detection
 * @address_list: The I2C addresses to probe (for detect)
 * @clients: List of detected clients we created (for i2c-core use only)
 *
 * The driver.owner field should be set to the module owner of this driver.
 * The driver.name field should be set to the name of this driver.
 *
 * For automatic device detection, both @detect and @address_list must
 * be defined. @class should also be set, otherwise only devices forced
 * with module parameters will be created. The detect function must
 * fill at least the name field of the i2c_board_info structure it is
 * handed upon successful detection, and possibly also the flags field.
 *
 * If @detect is missing, the driver will still work fine for enumerated
 * devices. Detected devices simply won't be supported. This is expected
 * for the many I2C/SMBus devices which can't be detected reliably, and
 * the ones which can always be enumerated in practice.
 *
 * The i2c_client structure which is handed to the @detect callback is
 * not a real i2c_client. It is initialized just enough so that you can
 * call i2c_smbus_read_byte_data and friends on it. Don't do anything
 * else with it. In particular, calling dev_dbg and friends on it is
 * not allowed.
 */
struct i2c_driver {
	unsigned int class;

	/* Notifies the driver that a new bus has appeared. You should avoid
	 * using this, it will be removed in a near future.
	 */
	int (*attach_adapter)(struct i2c_adapter *) __deprecated;

	/* Standard driver model interfaces */
	int (*probe)(struct i2c_client *, const struct i2c_device_id *);
	int (*remove)(struct i2c_client *);

	/* driver model interfaces that don't relate to enumeration  */
	void (*shutdown)(struct i2c_client *);

	/* Alert callback, for example for the SMBus alert protocol.
	 * The format and meaning of the data value depends on the protocol.
	 * For the SMBus alert protocol, there is a single bit of data passed
	 * as the alert response's low bit ("event flag").
	 */
	void (*alert)(struct i2c_client *, unsigned int data);

	/* a ioctl like command that can be used to perform specific functions
	 * with the device.
	 */
	int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);

	struct device_driver driver;
	const struct i2c_device_id *id_table;

	/* Device detection callback for automatic device creation */
	int (*detect)(struct i2c_client *, struct i2c_board_info *);
	const unsigned short *address_list;
	struct list_head clients;
};
#define to_i2c_driver(d) container_of(d, struct i2c_driver, driver)

/**
 * struct i2c_client - represent an I2C slave device
 * @flags: I2C_CLIENT_TEN indicates the device uses a ten bit chip address;
 *	I2C_CLIENT_PEC indicates it uses SMBus Packet Error Checking
 * @addr: Address used on the I2C bus connected to the parent adapter.
 * @name: Indicates the type of the device, usually a chip name that's
 *	generic enough to hide second-sourcing and compatible revisions.
 * @adapter: manages the bus segment hosting this I2C device
 * @dev: Driver model device node for the slave.
 * @irq: indicates the IRQ generated by this device (if any)
 * @detected: member of an i2c_driver.clients list or i2c-core's
 *	userspace_devices list
 * @slave_cb: Callback when I2C slave mode of an adapter is used. The adapter
 *	calls it to pass on slave events to the slave driver.
 *
 * An i2c_client identifies a single device (i.e. chip) connected to an
 * i2c bus. The behaviour exposed to Linux is defined by the driver
 * managing the device.
 */
struct i2c_client {
	unsigned short flags;		/* div., see below		*/
	unsigned short addr;		/* chip address - NOTE: 7bit	*/
					/* addresses are stored in the	*/
					/* _LOWER_ 7 bits		*/
	char name[I2C_NAME_SIZE];
	struct i2c_adapter *adapter;	/* the adapter we sit on	*/
	struct device dev;		/* the device structure		*/
	int irq;			/* irq issued by device		*/
	struct list_head detected;
#if IS_ENABLED(CONFIG_I2C_SLAVE)
	i2c_slave_cb_t slave_cb;	/* callback for slave mode	*/
#endif
};
#define to_i2c_client(d) container_of(d, struct i2c_client, dev)

extern struct i2c_client *i2c_verify_client(struct device *dev);
extern struct i2c_adapter *i2c_verify_adapter(struct device *dev);

static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
{
	struct device * const dev = container_of(kobj, struct device, kobj);
	return to_i2c_client(dev);
}

static inline void *i2c_get_clientdata(const struct i2c_client *dev)
{
	return dev_get_drvdata(&dev->dev);
}

static inline void i2c_set_clientdata(struct i2c_client *dev, void *data)
{
	dev_set_drvdata(&dev->dev, data);
}

/* I2C slave support */

#if IS_ENABLED(CONFIG_I2C_SLAVE)
enum i2c_slave_event {
	I2C_SLAVE_READ_REQUESTED,
	I2C_SLAVE_WRITE_REQUESTED,
	I2C_SLAVE_READ_PROCESSED,
	I2C_SLAVE_WRITE_RECEIVED,
	I2C_SLAVE_STOP,
};

extern int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
extern int i2c_slave_unregister(struct i2c_client *client);

static inline int i2c_slave_event(struct i2c_client *client,
				  enum i2c_slave_event event, u8 *val)
{
	return client->slave_cb(client, event, val);
}
#endif

/**
 * struct i2c_board_info - template for device creation
 * @type: chip type, to initialize i2c_client.name
 * @flags: to initialize i2c_client.flags
 * @addr: stored in i2c_client.addr
 * @platform_data: stored in i2c_client.dev.platform_data
 * @archdata: copied into i2c_client.dev.archdata
 * @of_node: pointer to OpenFirmware device node
 * @fwnode: device node supplied by the platform firmware
 * @irq: stored in i2c_client.irq
 *
 * I2C doesn't actually support hardware probing, although controllers and
 * devices may be able to use I2C_SMBUS_QUICK to tell whether or not there's
 * a device at a given address.  Drivers commonly need more information than
 * that, such as chip type, configuration, associated IRQ, and so on.
 *
 * i2c_board_info is used to build tables of information listing I2C devices
 * that are present.  This information is used to grow the driver model tree.
 * For mainboards this is done statically using i2c_register_board_info();
 * bus numbers identify adapters that aren't yet available.  For add-on boards,
 * i2c_new_device() does this dynamically with the adapter already known.
 */
struct i2c_board_info {
	char		type[I2C_NAME_SIZE];
	unsigned short	flags;
	unsigned short	addr;
	void		*platform_data;
	struct dev_archdata	*archdata;
	struct device_node *of_node;
	struct fwnode_handle *fwnode;
	int		irq;
};

/**
 * I2C_BOARD_INFO - macro used to list an i2c device and its address
 * @dev_type: identifies the device type
 * @dev_addr: the device's address on the bus.
 *
 * This macro initializes essential fields of a struct i2c_board_info,
 * declaring what has been provided on a particular board.  Optional
 * fields (such as associated irq, or device-specific platform_data)
 * are provided using conventional syntax.
 */
#define I2C_BOARD_INFO(dev_type, dev_addr) \
	.type = dev_type, .addr = (dev_addr)


#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
/* Add-on boards should register/unregister their devices; e.g. a board
 * with integrated I2C, a config eeprom, sensors, and a codec that's
 * used in conjunction with the primary hardware.
 */
extern struct i2c_client *
i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);

/* If you don't know the exact address of an I2C device, use this variant
 * instead, which can probe for device presence in a list of possible
 * addresses. The "probe" callback function is optional. If it is provided,
 * it must return 1 on successful probe, 0 otherwise. If it is not provided,
 * a default probing method is used.
 */
extern struct i2c_client *
i2c_new_probed_device(struct i2c_adapter *adap,
		      struct i2c_board_info *info,
		      unsigned short const *addr_list,
		      int (*probe)(struct i2c_adapter *, unsigned short addr));

/* Common custom probe functions */
extern int i2c_probe_func_quick_read(struct i2c_adapter *, unsigned short addr);

/* For devices that use several addresses, use i2c_new_dummy() to make
 * client handles for the extra addresses.
 */
extern struct i2c_client *
i2c_new_dummy(struct i2c_adapter *adap, u16 address);

extern void i2c_unregister_device(struct i2c_client *);
#endif /* I2C */

/* Mainboard arch_initcall() code should register all its I2C devices.
 * This is done at arch_initcall time, before declaring any i2c adapters.
 * Modules for add-on boards must use other calls.
 */
#ifdef CONFIG_I2C_BOARDINFO
extern int
i2c_register_board_info(int busnum, struct i2c_board_info const *info,
			unsigned n);
#else
static inline int
i2c_register_board_info(int busnum, struct i2c_board_info const *info,
			unsigned n)
{
	return 0;
}
#endif /* I2C_BOARDINFO */

/**
 * struct i2c_algorithm - represent I2C transfer method
 * @master_xfer: Issue a set of i2c transactions to the given I2C adapter
 *   defined by the msgs array, with num messages available to transfer via
 *   the adapter specified by adap.
 * @smbus_xfer: Issue smbus transactions to the given I2C adapter. If this
 *   is not present, then the bus layer will try and convert the SMBus calls
 *   into I2C transfers instead.
 * @functionality: Return the flags that this algorithm/adapter pair supports
 *   from the I2C_FUNC_* flags.
 * @reg_slave: Register given client to I2C slave mode of this adapter
 * @unreg_slave: Unregister given client from I2C slave mode of this adapter
 *
 * The following structs are for those who like to implement new bus drivers:
 * i2c_algorithm is the interface to a class of hardware solutions which can
 * be addressed using the same bus algorithms - i.e. bit-banging or the PCF8584
 * to name two of the most common.
 *
 * The return codes from the @master_xfer field should indicate the type of
 * error code that occurred during the transfer, as documented in the kernel
 * Documentation file Documentation/i2c/fault-codes.
 */
struct i2c_algorithm {
	/* If an adapter algorithm can't do I2C-level access, set master_xfer
	   to NULL. If an adapter algorithm can do SMBus access, set
	   smbus_xfer. If set to NULL, the SMBus protocol is simulated
	   using common I2C messages */
	/* master_xfer should return the number of messages successfully
	   processed, or a negative value on error */
	int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs,
			   int num);
	int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,
			   unsigned short flags, char read_write,
			   u8 command, int size, union i2c_smbus_data *data);

	/* To determine what the adapter supports */
	u32 (*functionality) (struct i2c_adapter *);

#if IS_ENABLED(CONFIG_I2C_SLAVE)
	int (*reg_slave)(struct i2c_client *client);
	int (*unreg_slave)(struct i2c_client *client);
#endif
};

/**
 * struct i2c_bus_recovery_info - I2C bus recovery information
 * @recover_bus: Recover routine. Either pass driver's recover_bus() routine, or
 *	i2c_generic_scl_recovery() or i2c_generic_gpio_recovery().
 * @get_scl: This gets current value of SCL line. Mandatory for generic SCL
 *      recovery. Used internally for generic GPIO recovery.
 * @set_scl: This sets/clears SCL line. Mandatory for generic SCL recovery. Used
 *      internally for generic GPIO recovery.
 * @get_sda: This gets current value of SDA line. Optional for generic SCL
 *      recovery. Used internally, if sda_gpio is a valid GPIO, for generic GPIO
 *      recovery.
 * @prepare_recovery: This will be called before starting recovery. Platform may
 *	configure padmux here for SDA/SCL line or something else they want.
 * @unprepare_recovery: This will be called after completing recovery. Platform
 *	may configure padmux here for SDA/SCL line or something else they want.
 * @scl_gpio: gpio number of the SCL line. Only required for GPIO recovery.
 * @sda_gpio: gpio number of the SDA line. Only required for GPIO recovery.
 */
struct i2c_bus_recovery_info {
	int (*recover_bus)(struct i2c_adapter *);

	int (*get_scl)(struct i2c_adapter *);
	void (*set_scl)(struct i2c_adapter *, int val);
	int (*get_sda)(struct i2c_adapter *);

	void (*prepare_recovery)(struct i2c_adapter *);
	void (*unprepare_recovery)(struct i2c_adapter *);

	/* gpio recovery */
	int scl_gpio;
	int sda_gpio;
};

int i2c_recover_bus(struct i2c_adapter *adap);

/* Generic recovery routines */
int i2c_generic_gpio_recovery(struct i2c_adapter *adap);
int i2c_generic_scl_recovery(struct i2c_adapter *adap);

/**
 * struct i2c_adapter_quirks - describe flaws of an i2c adapter
 * @flags: see I2C_AQ_* for possible flags and read below
 * @max_num_msgs: maximum number of messages per transfer
 * @max_write_len: maximum length of a write message
 * @max_read_len: maximum length of a read message
 * @max_comb_1st_msg_len: maximum length of the first msg in a combined message
 * @max_comb_2nd_msg_len: maximum length of the second msg in a combined message
 *
 * Note about combined messages: Some I2C controllers can only send one message
 * per transfer, plus something called combined message or write-then-read.
 * This is (usually) a small write message followed by a read message and
 * barely enough to access register based devices like EEPROMs. There is a flag
 * to support this mode. It implies max_num_msg = 2 and does the length checks
 * with max_comb_*_len because combined message mode usually has its own
 * limitations. Because of HW implementations, some controllers can actually do
 * write-then-anything or other variants. To support that, write-then-read has
 * been broken out into smaller bits like write-first and read-second which can
 * be combined as needed.
 */

struct i2c_adapter_quirks {
	u64 flags;
	int max_num_msgs;
	u16 max_write_len;
	u16 max_read_len;
	u16 max_comb_1st_msg_len;
	u16 max_comb_2nd_msg_len;
};

/* enforce max_num_msgs = 2 and use max_comb_*_len for length checks */
#define I2C_AQ_COMB			BIT(0)
/* first combined message must be write */
#define I2C_AQ_COMB_WRITE_FIRST		BIT(1)
/* second combined message must be read */
#define I2C_AQ_COMB_READ_SECOND		BIT(2)
/* both combined messages must have the same target address */
#define I2C_AQ_COMB_SAME_ADDR		BIT(3)
/* convenience macro for typical write-then read case */
#define I2C_AQ_COMB_WRITE_THEN_READ	(I2C_AQ_COMB | I2C_AQ_COMB_WRITE_FIRST | \
					 I2C_AQ_COMB_READ_SECOND | I2C_AQ_COMB_SAME_ADDR)

/*
 * i2c_adapter is the structure used to identify a physical i2c bus along
 * with the access algorithms necessary to access it.
 */
struct i2c_adapter {
	struct module *owner;
	unsigned int class;		  /* classes to allow probing for */
	const struct i2c_algorithm *algo; /* the algorithm to access the bus */
	void *algo_data;

	/* data fields that are valid for all devices	*/
	struct rt_mutex bus_lock;

	int timeout;			/* in jiffies */
	int retries;
	struct device dev;		/* the adapter device */

	int nr;
	char name[48];
	struct completion dev_released;

	struct mutex userspace_clients_lock;
	struct list_head userspace_clients;

	struct i2c_bus_recovery_info *bus_recovery_info;
	const struct i2c_adapter_quirks *quirks;
};
#define to_i2c_adapter(d) container_of(d, struct i2c_adapter, dev)

static inline void *i2c_get_adapdata(const struct i2c_adapter *dev)
{
	return dev_get_drvdata(&dev->dev);
}

static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
{
	dev_set_drvdata(&dev->dev, data);
}

static inline struct i2c_adapter *
i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
{
#if IS_ENABLED(CONFIG_I2C_MUX)
	struct device *parent = adapter->dev.parent;

	if (parent != NULL && parent->type == &i2c_adapter_type)
		return to_i2c_adapter(parent);
	else
#endif
		return NULL;
}

int i2c_for_each_dev(void *data, int (*fn)(struct device *, void *));

/* Adapter locking functions, exported for shared pin cases */
void i2c_lock_adapter(struct i2c_adapter *);
void i2c_unlock_adapter(struct i2c_adapter *);

/*flags for the client struct: */
#define I2C_CLIENT_PEC		0x04	/* Use Packet Error Checking */
#define I2C_CLIENT_TEN		0x10	/* we have a ten bit chip address */
					/* Must equal I2C_M_TEN below */
#define I2C_CLIENT_SLAVE	0x20	/* we are the slave */
#define I2C_CLIENT_WAKE		0x80	/* for board_info; true iff can wake */
#define I2C_CLIENT_SCCB		0x9000	/* Use Omnivision SCCB protocol */
					/* Must match I2C_M_STOP|IGNORE_NAK */

/* i2c adapter classes (bitmask) */
#define I2C_CLASS_HWMON		(1<<0)	/* lm_sensors, ... */
#define I2C_CLASS_DDC		(1<<3)	/* DDC bus on graphics adapters */
#define I2C_CLASS_SPD		(1<<7)	/* Memory modules */
#define I2C_CLASS_DEPRECATED	(1<<8)	/* Warn users that adapter will stop using classes */

/* Internal numbers to terminate lists */
#define I2C_CLIENT_END		0xfffeU

/* Construct an I2C_CLIENT_END-terminated array of i2c addresses */
#define I2C_ADDRS(addr, addrs...) \
	((const unsigned short []){ addr, ## addrs, I2C_CLIENT_END })


/* ----- functions exported by i2c.o */

/* administration...
 */
#if defined(CONFIG_I2C) || defined(CONFIG_I2C_MODULE)
extern int i2c_add_adapter(struct i2c_adapter *);
extern void i2c_del_adapter(struct i2c_adapter *);
extern int i2c_add_numbered_adapter(struct i2c_adapter *);

extern int i2c_register_driver(struct module *, struct i2c_driver *);
extern void i2c_del_driver(struct i2c_driver *);

/* use a define to avoid include chaining to get THIS_MODULE */
#define i2c_add_driver(driver) \
	i2c_register_driver(THIS_MODULE, driver)

extern struct i2c_client *i2c_use_client(struct i2c_client *client);
extern void i2c_release_client(struct i2c_client *client);

/* call the i2c_client->command() of all attached clients with
 * the given arguments */
extern void i2c_clients_command(struct i2c_adapter *adap,
				unsigned int cmd, void *arg);

extern struct i2c_adapter *i2c_get_adapter(int nr);
extern void i2c_put_adapter(struct i2c_adapter *adap);


/* Return the functionality mask */
static inline u32 i2c_get_functionality(struct i2c_adapter *adap)
{
	return adap->algo->functionality(adap);
}

/* Return 1 if adapter supports everything we need, 0 if not. */
static inline int i2c_check_functionality(struct i2c_adapter *adap, u32 func)
{
	return (func & i2c_get_functionality(adap)) == func;
}

/* Return the adapter number for a specific adapter */
static inline int i2c_adapter_id(struct i2c_adapter *adap)
{
	return adap->nr;
}

/**
 * module_i2c_driver() - Helper macro for registering a I2C driver
 * @__i2c_driver: i2c_driver struct
 *
 * Helper macro for I2C drivers which do not do anything special in module
 * init/exit. This eliminates a lot of boilerplate. Each module may only
 * use this macro once, and calling it replaces module_init() and module_exit()
 */
#define module_i2c_driver(__i2c_driver) \
	module_driver(__i2c_driver, i2c_add_driver, \
			i2c_del_driver)

#endif /* I2C */

#if IS_ENABLED(CONFIG_OF)
/* must call put_device() when done with returned i2c_client device */
extern struct i2c_client *of_find_i2c_device_by_node(struct device_node *node);

/* must call put_device() when done with returned i2c_adapter device */
extern struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node);

/* must call i2c_put_adapter() when done with returned i2c_adapter device */
struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node);
#else

static inline struct i2c_client *of_find_i2c_device_by_node(struct device_node *node)
{
	return NULL;
}

static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node *node)
{
	return NULL;
}

static inline struct i2c_adapter *of_get_i2c_adapter_by_node(struct device_node *node)
{
	return NULL;
}
#endif /* CONFIG_OF */

#endif /* _LINUX_I2C_H */