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1This is a small guide for those who want to write kernel drivers for I2C
2or SMBus devices.
3
4To set up a driver, you need to do several things. Some are optional, and
5some things can be done slightly or completely different. Use this as a
6guide, not as a rule book!
7
8
9General remarks
10===============
11
12Try to keep the kernel namespace as clean as possible. The best way to
13do this is to use a unique prefix for all global symbols. This is
14especially important for exported symbols, but it is a good idea to do
15it for non-exported symbols too. We will use the prefix `foo_' in this
16tutorial, and `FOO_' for preprocessor variables.
17
18
19The driver structure
20====================
21
22Usually, you will implement a single driver structure, and instantiate
23all clients from it. Remember, a driver structure contains general access
24routines, a client structure specific information like the actual I2C
25address.
26
27static struct i2c_driver foo_driver = {
28 .owner = THIS_MODULE,
29 .name = "Foo version 2.3 driver",
30 .flags = I2C_DF_NOTIFY,
31 .attach_adapter = &foo_attach_adapter,
32 .detach_client = &foo_detach_client,
33 .command = &foo_command /* may be NULL */
34}
35
36The name field must match the driver name, including the case. It must not
37contain spaces, and may be up to 31 characters long.
38
39Don't worry about the flags field; just put I2C_DF_NOTIFY into it. This
40means that your driver will be notified when new adapters are found.
41This is almost always what you want.
42
43All other fields are for call-back functions which will be explained
44below.
45
46
47Extra client data
48=================
49
50The client structure has a special `data' field that can point to any
51structure at all. You can use this to keep client-specific data. You
52do not always need this, but especially for `sensors' drivers, it can
53be very useful.
54
55An example structure is below.
56
57 struct foo_data {
58 struct i2c_client client;
59 struct semaphore lock; /* For ISA access in `sensors' drivers. */
60 int sysctl_id; /* To keep the /proc directory entry for
61 `sensors' drivers. */
62 enum chips type; /* To keep the chips type for `sensors' drivers. */
63
64 /* Because the i2c bus is slow, it is often useful to cache the read
65 information of a chip for some time (for example, 1 or 2 seconds).
66 It depends of course on the device whether this is really worthwhile
67 or even sensible. */
68 struct semaphore update_lock; /* When we are reading lots of information,
69 another process should not update the
70 below information */
71 char valid; /* != 0 if the following fields are valid. */
72 unsigned long last_updated; /* In jiffies */
73 /* Add the read information here too */
74 };
75
76
77Accessing the client
78====================
79
80Let's say we have a valid client structure. At some time, we will need
81to gather information from the client, or write new information to the
82client. How we will export this information to user-space is less
83important at this moment (perhaps we do not need to do this at all for
84some obscure clients). But we need generic reading and writing routines.
85
86I have found it useful to define foo_read and foo_write function for this.
87For some cases, it will be easier to call the i2c functions directly,
88but many chips have some kind of register-value idea that can easily
89be encapsulated. Also, some chips have both ISA and I2C interfaces, and
90it useful to abstract from this (only for `sensors' drivers).
91
92The below functions are simple examples, and should not be copied
93literally.
94
95 int foo_read_value(struct i2c_client *client, u8 reg)
96 {
97 if (reg < 0x10) /* byte-sized register */
98 return i2c_smbus_read_byte_data(client,reg);
99 else /* word-sized register */
100 return i2c_smbus_read_word_data(client,reg);
101 }
102
103 int foo_write_value(struct i2c_client *client, u8 reg, u16 value)
104 {
105 if (reg == 0x10) /* Impossible to write - driver error! */ {
106 return -1;
107 else if (reg < 0x10) /* byte-sized register */
108 return i2c_smbus_write_byte_data(client,reg,value);
109 else /* word-sized register */
110 return i2c_smbus_write_word_data(client,reg,value);
111 }
112
113For sensors code, you may have to cope with ISA registers too. Something
114like the below often works. Note the locking!
115
116 int foo_read_value(struct i2c_client *client, u8 reg)
117 {
118 int res;
119 if (i2c_is_isa_client(client)) {
120 down(&(((struct foo_data *) (client->data)) -> lock));
121 outb_p(reg,client->addr + FOO_ADDR_REG_OFFSET);
122 res = inb_p(client->addr + FOO_DATA_REG_OFFSET);
123 up(&(((struct foo_data *) (client->data)) -> lock));
124 return res;
125 } else
126 return i2c_smbus_read_byte_data(client,reg);
127 }
128
129Writing is done the same way.
130
131
132Probing and attaching
133=====================
134
135Most i2c devices can be present on several i2c addresses; for some this
136is determined in hardware (by soldering some chip pins to Vcc or Ground),
137for others this can be changed in software (by writing to specific client
138registers). Some devices are usually on a specific address, but not always;
139and some are even more tricky. So you will probably need to scan several
140i2c addresses for your clients, and do some sort of detection to see
141whether it is actually a device supported by your driver.
142
143To give the user a maximum of possibilities, some default module parameters
144are defined to help determine what addresses are scanned. Several macros
145are defined in i2c.h to help you support them, as well as a generic
146detection algorithm.
147
148You do not have to use this parameter interface; but don't try to use
149function i2c_probe() if you don't.
150
151NOTE: If you want to write a `sensors' driver, the interface is slightly
152 different! See below.
153
154
155
156Probing classes
157---------------
158
159All parameters are given as lists of unsigned 16-bit integers. Lists are
160terminated by I2C_CLIENT_END.
161The following lists are used internally:
162
163 normal_i2c: filled in by the module writer.
164 A list of I2C addresses which should normally be examined.
165 probe: insmod parameter.
166 A list of pairs. The first value is a bus number (-1 for any I2C bus),
167 the second is the address. These addresses are also probed, as if they
168 were in the 'normal' list.
169 ignore: insmod parameter.
170 A list of pairs. The first value is a bus number (-1 for any I2C bus),
171 the second is the I2C address. These addresses are never probed.
172 This parameter overrules the 'normal_i2c' list only.
173 force: insmod parameter.
174 A list of pairs. The first value is a bus number (-1 for any I2C bus),
175 the second is the I2C address. A device is blindly assumed to be on
176 the given address, no probing is done.
177
178Additionally, kind-specific force lists may optionally be defined if
179the driver supports several chip kinds. They are grouped in a
180NULL-terminated list of pointers named forces, those first element if the
181generic force list mentioned above. Each additional list correspond to an
182insmod parameter of the form force_<kind>.
183
184Fortunately, as a module writer, you just have to define the `normal_i2c'
185parameter. The complete declaration could look like this:
186
187 /* Scan 0x37, and 0x48 to 0x4f */
188 static unsigned short normal_i2c[] = { 0x37, 0x48, 0x49, 0x4a, 0x4b, 0x4c,
189 0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
190
191 /* Magic definition of all other variables and things */
192 I2C_CLIENT_INSMOD;
193 /* Or, if your driver supports, say, 2 kind of devices: */
194 I2C_CLIENT_INSMOD_2(foo, bar);
195
196If you use the multi-kind form, an enum will be defined for you:
197 enum chips { any_chip, foo, bar, ... }
198You can then (and certainly should) use it in the driver code.
199
200Note that you *have* to call the defined variable `normal_i2c',
201without any prefix!
202
203
204Attaching to an adapter
205-----------------------
206
207Whenever a new adapter is inserted, or for all adapters if the driver is
208being registered, the callback attach_adapter() is called. Now is the
209time to determine what devices are present on the adapter, and to register
210a client for each of them.
211
212The attach_adapter callback is really easy: we just call the generic
213detection function. This function will scan the bus for us, using the
214information as defined in the lists explained above. If a device is
215detected at a specific address, another callback is called.
216
217 int foo_attach_adapter(struct i2c_adapter *adapter)
218 {
219 return i2c_probe(adapter,&addr_data,&foo_detect_client);
220 }
221
222Remember, structure `addr_data' is defined by the macros explained above,
223so you do not have to define it yourself.
224
225The i2c_probe function will call the foo_detect_client
226function only for those i2c addresses that actually have a device on
227them (unless a `force' parameter was used). In addition, addresses that
228are already in use (by some other registered client) are skipped.
229
230
231The detect client function
232--------------------------
233
234The detect client function is called by i2c_probe. The `kind' parameter
235contains -1 for a probed detection, 0 for a forced detection, or a positive
236number for a forced detection with a chip type forced.
237
238Below, some things are only needed if this is a `sensors' driver. Those
239parts are between /* SENSORS ONLY START */ and /* SENSORS ONLY END */
240markers.
241
242Returning an error different from -ENODEV in a detect function will cause
243the detection to stop: other addresses and adapters won't be scanned.
244This should only be done on fatal or internal errors, such as a memory
245shortage or i2c_attach_client failing.
246
247For now, you can ignore the `flags' parameter. It is there for future use.
248
249 int foo_detect_client(struct i2c_adapter *adapter, int address,
250 unsigned short flags, int kind)
251 {
252 int err = 0;
253 int i;
254 struct i2c_client *new_client;
255 struct foo_data *data;
256 const char *client_name = ""; /* For non-`sensors' drivers, put the real
257 name here! */
258
259 /* Let's see whether this adapter can support what we need.
260 Please substitute the things you need here!
261 For `sensors' drivers, add `! is_isa &&' to the if statement */
262 if (!i2c_check_functionality(adapter,I2C_FUNC_SMBUS_WORD_DATA |
263 I2C_FUNC_SMBUS_WRITE_BYTE))
264 goto ERROR0;
265
266 /* SENSORS ONLY START */
267 const char *type_name = "";
268 int is_isa = i2c_is_isa_adapter(adapter);
269
270 /* Do this only if the chip can additionally be found on the ISA bus
271 (hybrid chip). */
272
273 if (is_isa) {
274
275 /* Discard immediately if this ISA range is already used */
276 /* FIXME: never use check_region(), only request_region() */
277 if (check_region(address,FOO_EXTENT))
278 goto ERROR0;
279
280 /* Probe whether there is anything on this address.
281 Some example code is below, but you will have to adapt this
282 for your own driver */
283
284 if (kind < 0) /* Only if no force parameter was used */ {
285 /* We may need long timeouts at least for some chips. */
286 #define REALLY_SLOW_IO
287 i = inb_p(address + 1);
288 if (inb_p(address + 2) != i)
289 goto ERROR0;
290 if (inb_p(address + 3) != i)
291 goto ERROR0;
292 if (inb_p(address + 7) != i)
293 goto ERROR0;
294 #undef REALLY_SLOW_IO
295
296 /* Let's just hope nothing breaks here */
297 i = inb_p(address + 5) & 0x7f;
298 outb_p(~i & 0x7f,address+5);
299 if ((inb_p(address + 5) & 0x7f) != (~i & 0x7f)) {
300 outb_p(i,address+5);
301 return 0;
302 }
303 }
304 }
305
306 /* SENSORS ONLY END */
307
308 /* OK. For now, we presume we have a valid client. We now create the
309 client structure, even though we cannot fill it completely yet.
310 But it allows us to access several i2c functions safely */
311
312 if (!(data = kzalloc(sizeof(struct foo_data), GFP_KERNEL))) {
313 err = -ENOMEM;
314 goto ERROR0;
315 }
316
317 new_client = &data->client;
318 i2c_set_clientdata(new_client, data);
319
320 new_client->addr = address;
321 new_client->adapter = adapter;
322 new_client->driver = &foo_driver;
323 new_client->flags = 0;
324
325 /* Now, we do the remaining detection. If no `force' parameter is used. */
326
327 /* First, the generic detection (if any), that is skipped if any force
328 parameter was used. */
329 if (kind < 0) {
330 /* The below is of course bogus */
331 if (foo_read(new_client,FOO_REG_GENERIC) != FOO_GENERIC_VALUE)
332 goto ERROR1;
333 }
334
335 /* SENSORS ONLY START */
336
337 /* Next, specific detection. This is especially important for `sensors'
338 devices. */
339
340 /* Determine the chip type. Not needed if a `force_CHIPTYPE' parameter
341 was used. */
342 if (kind <= 0) {
343 i = foo_read(new_client,FOO_REG_CHIPTYPE);
344 if (i == FOO_TYPE_1)
345 kind = chip1; /* As defined in the enum */
346 else if (i == FOO_TYPE_2)
347 kind = chip2;
348 else {
349 printk("foo: Ignoring 'force' parameter for unknown chip at "
350 "adapter %d, address 0x%02x\n",i2c_adapter_id(adapter),address);
351 goto ERROR1;
352 }
353 }
354
355 /* Now set the type and chip names */
356 if (kind == chip1) {
357 type_name = "chip1"; /* For /proc entry */
358 client_name = "CHIP 1";
359 } else if (kind == chip2) {
360 type_name = "chip2"; /* For /proc entry */
361 client_name = "CHIP 2";
362 }
363
364 /* Reserve the ISA region */
365 if (is_isa)
366 request_region(address,FOO_EXTENT,type_name);
367
368 /* SENSORS ONLY END */
369
370 /* Fill in the remaining client fields. */
371 strcpy(new_client->name,client_name);
372
373 /* SENSORS ONLY BEGIN */
374 data->type = kind;
375 /* SENSORS ONLY END */
376
377 data->valid = 0; /* Only if you use this field */
378 init_MUTEX(&data->update_lock); /* Only if you use this field */
379
380 /* Any other initializations in data must be done here too. */
381
382 /* Tell the i2c layer a new client has arrived */
383 if ((err = i2c_attach_client(new_client)))
384 goto ERROR3;
385
386 /* SENSORS ONLY BEGIN */
387 /* Register a new directory entry with module sensors. See below for
388 the `template' structure. */
389 if ((i = i2c_register_entry(new_client, type_name,
390 foo_dir_table_template,THIS_MODULE)) < 0) {
391 err = i;
392 goto ERROR4;
393 }
394 data->sysctl_id = i;
395
396 /* SENSORS ONLY END */
397
398 /* This function can write default values to the client registers, if
399 needed. */
400 foo_init_client(new_client);
401 return 0;
402
403 /* OK, this is not exactly good programming practice, usually. But it is
404 very code-efficient in this case. */
405
406 ERROR4:
407 i2c_detach_client(new_client);
408 ERROR3:
409 ERROR2:
410 /* SENSORS ONLY START */
411 if (is_isa)
412 release_region(address,FOO_EXTENT);
413 /* SENSORS ONLY END */
414 ERROR1:
415 kfree(new_client);
416 ERROR0:
417 return err;
418 }
419
420
421Removing the client
422===================
423
424The detach_client call back function is called when a client should be
425removed. It may actually fail, but only when panicking. This code is
426much simpler than the attachment code, fortunately!
427
428 int foo_detach_client(struct i2c_client *client)
429 {
430 int err,i;
431
432 /* SENSORS ONLY START */
433 /* Deregister with the `i2c-proc' module. */
434 i2c_deregister_entry(((struct lm78_data *)(client->data))->sysctl_id);
435 /* SENSORS ONLY END */
436
437 /* Try to detach the client from i2c space */
438 if ((err = i2c_detach_client(client)))
439 return err;
440
441 /* HYBRID SENSORS CHIP ONLY START */
442 if i2c_is_isa_client(client)
443 release_region(client->addr,LM78_EXTENT);
444 /* HYBRID SENSORS CHIP ONLY END */
445
446 kfree(data);
447 return 0;
448 }
449
450
451Initializing the module or kernel
452=================================
453
454When the kernel is booted, or when your foo driver module is inserted,
455you have to do some initializing. Fortunately, just attaching (registering)
456the driver module is usually enough.
457
458 /* Keep track of how far we got in the initialization process. If several
459 things have to initialized, and we fail halfway, only those things
460 have to be cleaned up! */
461 static int __initdata foo_initialized = 0;
462
463 static int __init foo_init(void)
464 {
465 int res;
466 printk("foo version %s (%s)\n",FOO_VERSION,FOO_DATE);
467
468 if ((res = i2c_add_driver(&foo_driver))) {
469 printk("foo: Driver registration failed, module not inserted.\n");
470 foo_cleanup();
471 return res;
472 }
473 foo_initialized ++;
474 return 0;
475 }
476
477 void foo_cleanup(void)
478 {
479 if (foo_initialized == 1) {
480 if ((res = i2c_del_driver(&foo_driver))) {
481 printk("foo: Driver registration failed, module not removed.\n");
482 return;
483 }
484 foo_initialized --;
485 }
486 }
487
488 /* Substitute your own name and email address */
489 MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>"
490 MODULE_DESCRIPTION("Driver for Barf Inc. Foo I2C devices");
491
492 module_init(foo_init);
493 module_exit(foo_cleanup);
494
495Note that some functions are marked by `__init', and some data structures
496by `__init_data'. Hose functions and structures can be removed after
497kernel booting (or module loading) is completed.
498
499Command function
500================
501
502A generic ioctl-like function call back is supported. You will seldom
503need this. You may even set it to NULL.
504
505 /* No commands defined */
506 int foo_command(struct i2c_client *client, unsigned int cmd, void *arg)
507 {
508 return 0;
509 }
510
511
512Sending and receiving
513=====================
514
515If you want to communicate with your device, there are several functions
516to do this. You can find all of them in i2c.h.
517
518If you can choose between plain i2c communication and SMBus level
519communication, please use the last. All adapters understand SMBus level
520commands, but only some of them understand plain i2c!
521
522
523Plain i2c communication
524-----------------------
525
526 extern int i2c_master_send(struct i2c_client *,const char* ,int);
527 extern int i2c_master_recv(struct i2c_client *,char* ,int);
528
529These routines read and write some bytes from/to a client. The client
530contains the i2c address, so you do not have to include it. The second
531parameter contains the bytes the read/write, the third the length of the
532buffer. Returned is the actual number of bytes read/written.
533
534 extern int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msg,
535 int num);
536
537This sends a series of messages. Each message can be a read or write,
538and they can be mixed in any way. The transactions are combined: no
539stop bit is sent between transaction. The i2c_msg structure contains
540for each message the client address, the number of bytes of the message
541and the message data itself.
542
543You can read the file `i2c-protocol' for more information about the
544actual i2c protocol.
545
546
547SMBus communication
548-------------------
549
550 extern s32 i2c_smbus_xfer (struct i2c_adapter * adapter, u16 addr,
551 unsigned short flags,
552 char read_write, u8 command, int size,
553 union i2c_smbus_data * data);
554
555 This is the generic SMBus function. All functions below are implemented
556 in terms of it. Never use this function directly!
557
558
559 extern s32 i2c_smbus_write_quick(struct i2c_client * client, u8 value);
560 extern s32 i2c_smbus_read_byte(struct i2c_client * client);
561 extern s32 i2c_smbus_write_byte(struct i2c_client * client, u8 value);
562 extern s32 i2c_smbus_read_byte_data(struct i2c_client * client, u8 command);
563 extern s32 i2c_smbus_write_byte_data(struct i2c_client * client,
564 u8 command, u8 value);
565 extern s32 i2c_smbus_read_word_data(struct i2c_client * client, u8 command);
566 extern s32 i2c_smbus_write_word_data(struct i2c_client * client,
567 u8 command, u16 value);
568 extern s32 i2c_smbus_write_block_data(struct i2c_client * client,
569 u8 command, u8 length,
570 u8 *values);
571 extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client * client,
572 u8 command, u8 *values);
573
574These ones were removed in Linux 2.6.10 because they had no users, but could
575be added back later if needed:
576
577 extern s32 i2c_smbus_read_block_data(struct i2c_client * client,
578 u8 command, u8 *values);
579 extern s32 i2c_smbus_write_i2c_block_data(struct i2c_client * client,
580 u8 command, u8 length,
581 u8 *values);
582 extern s32 i2c_smbus_process_call(struct i2c_client * client,
583 u8 command, u16 value);
584 extern s32 i2c_smbus_block_process_call(struct i2c_client *client,
585 u8 command, u8 length,
586 u8 *values)
587
588All these transactions return -1 on failure. The 'write' transactions
589return 0 on success; the 'read' transactions return the read value, except
590for read_block, which returns the number of values read. The block buffers
591need not be longer than 32 bytes.
592
593You can read the file `smbus-protocol' for more information about the
594actual SMBus protocol.
595
596
597General purpose routines
598========================
599
600Below all general purpose routines are listed, that were not mentioned
601before.
602
603 /* This call returns a unique low identifier for each registered adapter,
604 * or -1 if the adapter was not registered.
605 */
606 extern int i2c_adapter_id(struct i2c_adapter *adap);
607
608
609The sensors sysctl/proc interface
610=================================
611
612This section only applies if you write `sensors' drivers.
613
614Each sensors driver creates a directory in /proc/sys/dev/sensors for each
615registered client. The directory is called something like foo-i2c-4-65.
616The sensors module helps you to do this as easily as possible.
617
618The template
619------------
620
621You will need to define a ctl_table template. This template will automatically
622be copied to a newly allocated structure and filled in where necessary when
623you call sensors_register_entry.
624
625First, I will give an example definition.
626 static ctl_table foo_dir_table_template[] = {
627 { FOO_SYSCTL_FUNC1, "func1", NULL, 0, 0644, NULL, &i2c_proc_real,
628 &i2c_sysctl_real,NULL,&foo_func },
629 { FOO_SYSCTL_FUNC2, "func2", NULL, 0, 0644, NULL, &i2c_proc_real,
630 &i2c_sysctl_real,NULL,&foo_func },
631 { FOO_SYSCTL_DATA, "data", NULL, 0, 0644, NULL, &i2c_proc_real,
632 &i2c_sysctl_real,NULL,&foo_data },
633 { 0 }
634 };
635
636In the above example, three entries are defined. They can either be
637accessed through the /proc interface, in the /proc/sys/dev/sensors/*
638directories, as files named func1, func2 and data, or alternatively
639through the sysctl interface, in the appropriate table, with identifiers
640FOO_SYSCTL_FUNC1, FOO_SYSCTL_FUNC2 and FOO_SYSCTL_DATA.
641
642The third, sixth and ninth parameters should always be NULL, and the
643fourth should always be 0. The fifth is the mode of the /proc file;
6440644 is safe, as the file will be owned by root:root.
645
646The seventh and eighth parameters should be &i2c_proc_real and
647&i2c_sysctl_real if you want to export lists of reals (scaled
648integers). You can also use your own function for them, as usual.
649Finally, the last parameter is the call-back to gather the data
650(see below) if you use the *_proc_real functions.
651
652
653Gathering the data
654------------------
655
656The call back functions (foo_func and foo_data in the above example)
657can be called in several ways; the operation parameter determines
658what should be done:
659
660 * If operation == SENSORS_PROC_REAL_INFO, you must return the
661 magnitude (scaling) in nrels_mag;
662 * If operation == SENSORS_PROC_REAL_READ, you must read information
663 from the chip and return it in results. The number of integers
664 to display should be put in nrels_mag;
665 * If operation == SENSORS_PROC_REAL_WRITE, you must write the
666 supplied information to the chip. nrels_mag will contain the number
667 of integers, results the integers themselves.
668
669The *_proc_real functions will display the elements as reals for the
670/proc interface. If you set the magnitude to 2, and supply 345 for
671SENSORS_PROC_REAL_READ, it would display 3.45; and if the user would
672write 45.6 to the /proc file, it would be returned as 4560 for
673SENSORS_PROC_REAL_WRITE. A magnitude may even be negative!
674
675An example function:
676
677 /* FOO_FROM_REG and FOO_TO_REG translate between scaled values and
678 register values. Note the use of the read cache. */
679 void foo_in(struct i2c_client *client, int operation, int ctl_name,
680 int *nrels_mag, long *results)
681 {
682 struct foo_data *data = client->data;
683 int nr = ctl_name - FOO_SYSCTL_FUNC1; /* reduce to 0 upwards */
684
685 if (operation == SENSORS_PROC_REAL_INFO)
686 *nrels_mag = 2;
687 else if (operation == SENSORS_PROC_REAL_READ) {
688 /* Update the readings cache (if necessary) */
689 foo_update_client(client);
690 /* Get the readings from the cache */
691 results[0] = FOO_FROM_REG(data->foo_func_base[nr]);
692 results[1] = FOO_FROM_REG(data->foo_func_more[nr]);
693 results[2] = FOO_FROM_REG(data->foo_func_readonly[nr]);
694 *nrels_mag = 2;
695 } else if (operation == SENSORS_PROC_REAL_WRITE) {
696 if (*nrels_mag >= 1) {
697 /* Update the cache */
698 data->foo_base[nr] = FOO_TO_REG(results[0]);
699 /* Update the chip */
700 foo_write_value(client,FOO_REG_FUNC_BASE(nr),data->foo_base[nr]);
701 }
702 if (*nrels_mag >= 2) {
703 /* Update the cache */
704 data->foo_more[nr] = FOO_TO_REG(results[1]);
705 /* Update the chip */
706 foo_write_value(client,FOO_REG_FUNC_MORE(nr),data->foo_more[nr]);
707 }
708 }
709 }