1/*
2 * Linux I2C core SMBus and SMBus emulation code
3 *
4 * This file contains the SMBus functions which are always included in the I2C
5 * core because they can be emulated via I2C. SMBus specific extensions
6 * (e.g. smbalert) are handled in a seperate i2c-smbus module.
7 *
8 * All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
9 * SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
10 * Jean Delvare <jdelvare@suse.de>
11 *
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License as published by the Free
14 * Software Foundation; either version 2 of the License, or (at your option)
15 * any later version.
16 */
17#include <linux/device.h>
18#include <linux/err.h>
19#include <linux/i2c.h>
20#include <linux/i2c-smbus.h>
21#include <linux/slab.h>
22
23#define CREATE_TRACE_POINTS
24#include <trace/events/smbus.h>
25
26
27/* The SMBus parts */
28
29#define POLY (0x1070U << 3)
30static u8 crc8(u16 data)
31{
32 int i;
33
34 for (i = 0; i < 8; i++) {
35 if (data & 0x8000)
36 data = data ^ POLY;
37 data = data << 1;
38 }
39 return (u8)(data >> 8);
40}
41
42/* Incremental CRC8 over count bytes in the array pointed to by p */
43static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
44{
45 int i;
46
47 for (i = 0; i < count; i++)
48 crc = crc8((crc ^ p[i]) << 8);
49 return crc;
50}
51
52/* Assume a 7-bit address, which is reasonable for SMBus */
53static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
54{
55 /* The address will be sent first */
56 u8 addr = i2c_8bit_addr_from_msg(msg);
57 pec = i2c_smbus_pec(pec, &addr, 1);
58
59 /* The data buffer follows */
60 return i2c_smbus_pec(pec, msg->buf, msg->len);
61}
62
63/* Used for write only transactions */
64static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
65{
66 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
67 msg->len++;
68}
69
70/* Return <0 on CRC error
71 If there was a write before this read (most cases) we need to take the
72 partial CRC from the write part into account.
73 Note that this function does modify the message (we need to decrease the
74 message length to hide the CRC byte from the caller). */
75static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
76{
77 u8 rpec = msg->buf[--msg->len];
78 cpec = i2c_smbus_msg_pec(cpec, msg);
79
80 if (rpec != cpec) {
81 pr_debug("Bad PEC 0x%02x vs. 0x%02x\n",
82 rpec, cpec);
83 return -EBADMSG;
84 }
85 return 0;
86}
87
88/**
89 * i2c_smbus_read_byte - SMBus "receive byte" protocol
90 * @client: Handle to slave device
91 *
92 * This executes the SMBus "receive byte" protocol, returning negative errno
93 * else the byte received from the device.
94 */
95s32 i2c_smbus_read_byte(const struct i2c_client *client)
96{
97 union i2c_smbus_data data;
98 int status;
99
100 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
101 I2C_SMBUS_READ, 0,
102 I2C_SMBUS_BYTE, &data);
103 return (status < 0) ? status : data.byte;
104}
105EXPORT_SYMBOL(i2c_smbus_read_byte);
106
107/**
108 * i2c_smbus_write_byte - SMBus "send byte" protocol
109 * @client: Handle to slave device
110 * @value: Byte to be sent
111 *
112 * This executes the SMBus "send byte" protocol, returning negative errno
113 * else zero on success.
114 */
115s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
116{
117 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
118 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
119}
120EXPORT_SYMBOL(i2c_smbus_write_byte);
121
122/**
123 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
124 * @client: Handle to slave device
125 * @command: Byte interpreted by slave
126 *
127 * This executes the SMBus "read byte" protocol, returning negative errno
128 * else a data byte received from the device.
129 */
130s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
131{
132 union i2c_smbus_data data;
133 int status;
134
135 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
136 I2C_SMBUS_READ, command,
137 I2C_SMBUS_BYTE_DATA, &data);
138 return (status < 0) ? status : data.byte;
139}
140EXPORT_SYMBOL(i2c_smbus_read_byte_data);
141
142/**
143 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
144 * @client: Handle to slave device
145 * @command: Byte interpreted by slave
146 * @value: Byte being written
147 *
148 * This executes the SMBus "write byte" protocol, returning negative errno
149 * else zero on success.
150 */
151s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
152 u8 value)
153{
154 union i2c_smbus_data data;
155 data.byte = value;
156 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
157 I2C_SMBUS_WRITE, command,
158 I2C_SMBUS_BYTE_DATA, &data);
159}
160EXPORT_SYMBOL(i2c_smbus_write_byte_data);
161
162/**
163 * i2c_smbus_read_word_data - SMBus "read word" protocol
164 * @client: Handle to slave device
165 * @command: Byte interpreted by slave
166 *
167 * This executes the SMBus "read word" protocol, returning negative errno
168 * else a 16-bit unsigned "word" received from the device.
169 */
170s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
171{
172 union i2c_smbus_data data;
173 int status;
174
175 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
176 I2C_SMBUS_READ, command,
177 I2C_SMBUS_WORD_DATA, &data);
178 return (status < 0) ? status : data.word;
179}
180EXPORT_SYMBOL(i2c_smbus_read_word_data);
181
182/**
183 * i2c_smbus_write_word_data - SMBus "write word" protocol
184 * @client: Handle to slave device
185 * @command: Byte interpreted by slave
186 * @value: 16-bit "word" being written
187 *
188 * This executes the SMBus "write word" protocol, returning negative errno
189 * else zero on success.
190 */
191s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
192 u16 value)
193{
194 union i2c_smbus_data data;
195 data.word = value;
196 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
197 I2C_SMBUS_WRITE, command,
198 I2C_SMBUS_WORD_DATA, &data);
199}
200EXPORT_SYMBOL(i2c_smbus_write_word_data);
201
202/**
203 * i2c_smbus_read_block_data - SMBus "block read" protocol
204 * @client: Handle to slave device
205 * @command: Byte interpreted by slave
206 * @values: Byte array into which data will be read; big enough to hold
207 * the data returned by the slave. SMBus allows at most 32 bytes.
208 *
209 * This executes the SMBus "block read" protocol, returning negative errno
210 * else the number of data bytes in the slave's response.
211 *
212 * Note that using this function requires that the client's adapter support
213 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
214 * support this; its emulation through I2C messaging relies on a specific
215 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
216 */
217s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
218 u8 *values)
219{
220 union i2c_smbus_data data;
221 int status;
222
223 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
224 I2C_SMBUS_READ, command,
225 I2C_SMBUS_BLOCK_DATA, &data);
226 if (status)
227 return status;
228
229 memcpy(values, &data.block[1], data.block[0]);
230 return data.block[0];
231}
232EXPORT_SYMBOL(i2c_smbus_read_block_data);
233
234/**
235 * i2c_smbus_write_block_data - SMBus "block write" protocol
236 * @client: Handle to slave device
237 * @command: Byte interpreted by slave
238 * @length: Size of data block; SMBus allows at most 32 bytes
239 * @values: Byte array which will be written.
240 *
241 * This executes the SMBus "block write" protocol, returning negative errno
242 * else zero on success.
243 */
244s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
245 u8 length, const u8 *values)
246{
247 union i2c_smbus_data data;
248
249 if (length > I2C_SMBUS_BLOCK_MAX)
250 length = I2C_SMBUS_BLOCK_MAX;
251 data.block[0] = length;
252 memcpy(&data.block[1], values, length);
253 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
254 I2C_SMBUS_WRITE, command,
255 I2C_SMBUS_BLOCK_DATA, &data);
256}
257EXPORT_SYMBOL(i2c_smbus_write_block_data);
258
259/* Returns the number of read bytes */
260s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
261 u8 length, u8 *values)
262{
263 union i2c_smbus_data data;
264 int status;
265
266 if (length > I2C_SMBUS_BLOCK_MAX)
267 length = I2C_SMBUS_BLOCK_MAX;
268 data.block[0] = length;
269 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
270 I2C_SMBUS_READ, command,
271 I2C_SMBUS_I2C_BLOCK_DATA, &data);
272 if (status < 0)
273 return status;
274
275 memcpy(values, &data.block[1], data.block[0]);
276 return data.block[0];
277}
278EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
279
280s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
281 u8 length, const u8 *values)
282{
283 union i2c_smbus_data data;
284
285 if (length > I2C_SMBUS_BLOCK_MAX)
286 length = I2C_SMBUS_BLOCK_MAX;
287 data.block[0] = length;
288 memcpy(data.block + 1, values, length);
289 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
290 I2C_SMBUS_WRITE, command,
291 I2C_SMBUS_I2C_BLOCK_DATA, &data);
292}
293EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
294
295static void i2c_smbus_try_get_dmabuf(struct i2c_msg *msg, u8 init_val)
296{
297 bool is_read = msg->flags & I2C_M_RD;
298 unsigned char *dma_buf;
299
300 dma_buf = kzalloc(I2C_SMBUS_BLOCK_MAX + (is_read ? 2 : 3), GFP_KERNEL);
301 if (!dma_buf)
302 return;
303
304 msg->buf = dma_buf;
305 msg->flags |= I2C_M_DMA_SAFE;
306
307 if (init_val)
308 msg->buf[0] = init_val;
309}
310
311/*
312 * Simulate a SMBus command using the I2C protocol.
313 * No checking of parameters is done!
314 */
315static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
316 unsigned short flags,
317 char read_write, u8 command, int size,
318 union i2c_smbus_data *data)
319{
320 /*
321 * So we need to generate a series of msgs. In the case of writing, we
322 * need to use only one message; when reading, we need two. We
323 * initialize most things with sane defaults, to keep the code below
324 * somewhat simpler.
325 */
326 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
327 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
328 int num = read_write == I2C_SMBUS_READ ? 2 : 1;
329 int i;
330 u8 partial_pec = 0;
331 int status;
332 struct i2c_msg msg[2] = {
333 {
334 .addr = addr,
335 .flags = flags,
336 .len = 1,
337 .buf = msgbuf0,
338 }, {
339 .addr = addr,
340 .flags = flags | I2C_M_RD,
341 .len = 0,
342 .buf = msgbuf1,
343 },
344 };
345
346 msgbuf0[0] = command;
347 switch (size) {
348 case I2C_SMBUS_QUICK:
349 msg[0].len = 0;
350 /* Special case: The read/write field is used as data */
351 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
352 I2C_M_RD : 0);
353 num = 1;
354 break;
355 case I2C_SMBUS_BYTE:
356 if (read_write == I2C_SMBUS_READ) {
357 /* Special case: only a read! */
358 msg[0].flags = I2C_M_RD | flags;
359 num = 1;
360 }
361 break;
362 case I2C_SMBUS_BYTE_DATA:
363 if (read_write == I2C_SMBUS_READ)
364 msg[1].len = 1;
365 else {
366 msg[0].len = 2;
367 msgbuf0[1] = data->byte;
368 }
369 break;
370 case I2C_SMBUS_WORD_DATA:
371 if (read_write == I2C_SMBUS_READ)
372 msg[1].len = 2;
373 else {
374 msg[0].len = 3;
375 msgbuf0[1] = data->word & 0xff;
376 msgbuf0[2] = data->word >> 8;
377 }
378 break;
379 case I2C_SMBUS_PROC_CALL:
380 num = 2; /* Special case */
381 read_write = I2C_SMBUS_READ;
382 msg[0].len = 3;
383 msg[1].len = 2;
384 msgbuf0[1] = data->word & 0xff;
385 msgbuf0[2] = data->word >> 8;
386 break;
387 case I2C_SMBUS_BLOCK_DATA:
388 if (read_write == I2C_SMBUS_READ) {
389 msg[1].flags |= I2C_M_RECV_LEN;
390 msg[1].len = 1; /* block length will be added by
391 the underlying bus driver */
392 i2c_smbus_try_get_dmabuf(&msg[1], 0);
393 } else {
394 msg[0].len = data->block[0] + 2;
395 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
396 dev_err(&adapter->dev,
397 "Invalid block write size %d\n",
398 data->block[0]);
399 return -EINVAL;
400 }
401
402 i2c_smbus_try_get_dmabuf(&msg[0], command);
403 for (i = 1; i < msg[0].len; i++)
404 msg[0].buf[i] = data->block[i - 1];
405 }
406 break;
407 case I2C_SMBUS_BLOCK_PROC_CALL:
408 num = 2; /* Another special case */
409 read_write = I2C_SMBUS_READ;
410 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
411 dev_err(&adapter->dev,
412 "Invalid block write size %d\n",
413 data->block[0]);
414 return -EINVAL;
415 }
416
417 msg[0].len = data->block[0] + 2;
418 i2c_smbus_try_get_dmabuf(&msg[0], command);
419 for (i = 1; i < msg[0].len; i++)
420 msg[0].buf[i] = data->block[i - 1];
421
422 msg[1].flags |= I2C_M_RECV_LEN;
423 msg[1].len = 1; /* block length will be added by
424 the underlying bus driver */
425 i2c_smbus_try_get_dmabuf(&msg[1], 0);
426 break;
427 case I2C_SMBUS_I2C_BLOCK_DATA:
428 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
429 dev_err(&adapter->dev, "Invalid block %s size %d\n",
430 read_write == I2C_SMBUS_READ ? "read" : "write",
431 data->block[0]);
432 return -EINVAL;
433 }
434
435 if (read_write == I2C_SMBUS_READ) {
436 msg[1].len = data->block[0];
437 i2c_smbus_try_get_dmabuf(&msg[1], 0);
438 } else {
439 msg[0].len = data->block[0] + 1;
440
441 i2c_smbus_try_get_dmabuf(&msg[0], command);
442 for (i = 1; i <= data->block[0]; i++)
443 msg[0].buf[i] = data->block[i];
444 }
445 break;
446 default:
447 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
448 return -EOPNOTSUPP;
449 }
450
451 i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
452 && size != I2C_SMBUS_I2C_BLOCK_DATA);
453 if (i) {
454 /* Compute PEC if first message is a write */
455 if (!(msg[0].flags & I2C_M_RD)) {
456 if (num == 1) /* Write only */
457 i2c_smbus_add_pec(&msg[0]);
458 else /* Write followed by read */
459 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
460 }
461 /* Ask for PEC if last message is a read */
462 if (msg[num-1].flags & I2C_M_RD)
463 msg[num-1].len++;
464 }
465
466 status = __i2c_transfer(adapter, msg, num);
467 if (status < 0)
468 goto cleanup;
469 if (status != num) {
470 status = -EIO;
471 goto cleanup;
472 }
473 status = 0;
474
475 /* Check PEC if last message is a read */
476 if (i && (msg[num-1].flags & I2C_M_RD)) {
477 status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
478 if (status < 0)
479 goto cleanup;
480 }
481
482 if (read_write == I2C_SMBUS_READ)
483 switch (size) {
484 case I2C_SMBUS_BYTE:
485 data->byte = msgbuf0[0];
486 break;
487 case I2C_SMBUS_BYTE_DATA:
488 data->byte = msgbuf1[0];
489 break;
490 case I2C_SMBUS_WORD_DATA:
491 case I2C_SMBUS_PROC_CALL:
492 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
493 break;
494 case I2C_SMBUS_I2C_BLOCK_DATA:
495 for (i = 0; i < data->block[0]; i++)
496 data->block[i + 1] = msg[1].buf[i];
497 break;
498 case I2C_SMBUS_BLOCK_DATA:
499 case I2C_SMBUS_BLOCK_PROC_CALL:
500 for (i = 0; i < msg[1].buf[0] + 1; i++)
501 data->block[i] = msg[1].buf[i];
502 break;
503 }
504
505cleanup:
506 if (msg[0].flags & I2C_M_DMA_SAFE)
507 kfree(msg[0].buf);
508 if (msg[1].flags & I2C_M_DMA_SAFE)
509 kfree(msg[1].buf);
510
511 return status;
512}
513
514/**
515 * i2c_smbus_xfer - execute SMBus protocol operations
516 * @adapter: Handle to I2C bus
517 * @addr: Address of SMBus slave on that bus
518 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
519 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
520 * @command: Byte interpreted by slave, for protocols which use such bytes
521 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
522 * @data: Data to be read or written
523 *
524 * This executes an SMBus protocol operation, and returns a negative
525 * errno code else zero on success.
526 */
527s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
528 unsigned short flags, char read_write,
529 u8 command, int protocol, union i2c_smbus_data *data)
530{
531 s32 res;
532
533 i2c_lock_bus(adapter, I2C_LOCK_SEGMENT);
534 res = __i2c_smbus_xfer(adapter, addr, flags, read_write,
535 command, protocol, data);
536 i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT);
537
538 return res;
539}
540EXPORT_SYMBOL(i2c_smbus_xfer);
541
542s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
543 unsigned short flags, char read_write,
544 u8 command, int protocol, union i2c_smbus_data *data)
545{
546 unsigned long orig_jiffies;
547 int try;
548 s32 res;
549
550 /* If enabled, the following two tracepoints are conditional on
551 * read_write and protocol.
552 */
553 trace_smbus_write(adapter, addr, flags, read_write,
554 command, protocol, data);
555 trace_smbus_read(adapter, addr, flags, read_write,
556 command, protocol);
557
558 flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
559
560 if (adapter->algo->smbus_xfer) {
561 /* Retry automatically on arbitration loss */
562 orig_jiffies = jiffies;
563 for (res = 0, try = 0; try <= adapter->retries; try++) {
564 res = adapter->algo->smbus_xfer(adapter, addr, flags,
565 read_write, command,
566 protocol, data);
567 if (res != -EAGAIN)
568 break;
569 if (time_after(jiffies,
570 orig_jiffies + adapter->timeout))
571 break;
572 }
573
574 if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
575 goto trace;
576 /*
577 * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
578 * implement native support for the SMBus operation.
579 */
580 }
581
582 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
583 command, protocol, data);
584
585trace:
586 /* If enabled, the reply tracepoint is conditional on read_write. */
587 trace_smbus_reply(adapter, addr, flags, read_write,
588 command, protocol, data, res);
589 trace_smbus_result(adapter, addr, flags, read_write,
590 command, protocol, res);
591
592 return res;
593}
594EXPORT_SYMBOL(__i2c_smbus_xfer);
595
596/**
597 * i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate
598 * @client: Handle to slave device
599 * @command: Byte interpreted by slave
600 * @length: Size of data block; SMBus allows at most I2C_SMBUS_BLOCK_MAX bytes
601 * @values: Byte array into which data will be read; big enough to hold
602 * the data returned by the slave. SMBus allows at most
603 * I2C_SMBUS_BLOCK_MAX bytes.
604 *
605 * This executes the SMBus "block read" protocol if supported by the adapter.
606 * If block read is not supported, it emulates it using either word or byte
607 * read protocols depending on availability.
608 *
609 * The addresses of the I2C slave device that are accessed with this function
610 * must be mapped to a linear region, so that a block read will have the same
611 * effect as a byte read. Before using this function you must double-check
612 * if the I2C slave does support exchanging a block transfer with a byte
613 * transfer.
614 */
615s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
616 u8 command, u8 length, u8 *values)
617{
618 u8 i = 0;
619 int status;
620
621 if (length > I2C_SMBUS_BLOCK_MAX)
622 length = I2C_SMBUS_BLOCK_MAX;
623
624 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
625 return i2c_smbus_read_i2c_block_data(client, command, length, values);
626
627 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA))
628 return -EOPNOTSUPP;
629
630 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) {
631 while ((i + 2) <= length) {
632 status = i2c_smbus_read_word_data(client, command + i);
633 if (status < 0)
634 return status;
635 values[i] = status & 0xff;
636 values[i + 1] = status >> 8;
637 i += 2;
638 }
639 }
640
641 while (i < length) {
642 status = i2c_smbus_read_byte_data(client, command + i);
643 if (status < 0)
644 return status;
645 values[i] = status;
646 i++;
647 }
648
649 return i;
650}
651EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data_or_emulated);
652
653/**
654 * i2c_setup_smbus_alert - Setup SMBus alert support
655 * @adapter: the target adapter
656 * @setup: setup data for the SMBus alert handler
657 * Context: can sleep
658 *
659 * Setup handling of the SMBus alert protocol on a given I2C bus segment.
660 *
661 * Handling can be done either through our IRQ handler, or by the
662 * adapter (from its handler, periodic polling, or whatever).
663 *
664 * NOTE that if we manage the IRQ, we *MUST* know if it's level or
665 * edge triggered in order to hand it to the workqueue correctly.
666 * If triggering the alert seems to wedge the system, you probably
667 * should have said it's level triggered.
668 *
669 * This returns the ara client, which should be saved for later use with
670 * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
671 * to indicate an error.
672 */
673struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
674 struct i2c_smbus_alert_setup *setup)
675{
676 struct i2c_board_info ara_board_info = {
677 I2C_BOARD_INFO("smbus_alert", 0x0c),
678 .platform_data = setup,
679 };
680
681 return i2c_new_device(adapter, &ara_board_info);
682}
683EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
684
685#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF)
686int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter)
687{
688 struct i2c_client *client;
689 int irq;
690
691 irq = of_property_match_string(adapter->dev.of_node, "interrupt-names",
692 "smbus_alert");
693 if (irq == -EINVAL || irq == -ENODATA)
694 return 0;
695 else if (irq < 0)
696 return irq;
697
698 client = i2c_setup_smbus_alert(adapter, NULL);
699 if (!client)
700 return -ENODEV;
701
702 return 0;
703}
704EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert);
705#endif
706