1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Linux I2C core SMBus and SMBus emulation code
4 *
5 * This file contains the SMBus functions which are always included in the I2C
6 * core because they can be emulated via I2C. SMBus specific extensions
7 * (e.g. smbalert) are handled in a separate i2c-smbus module.
8 *
9 * All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
10 * SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
11 * Jean Delvare <jdelvare@suse.de>
12 */
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/i2c.h>
16 #include <linux/i2c-smbus.h>
17 #include <linux/property.h>
18 #include <linux/slab.h>
19
20 #include "i2c-core.h"
21
22 #define CREATE_TRACE_POINTS
23 #include <trace/events/smbus.h>
24
25
26 /* The SMBus parts */
27
28 #define POLY (0x1070U << 3)
crc8(u16 data)29 static u8 crc8(u16 data)
30 {
31 int i;
32
33 for (i = 0; i < 8; i++) {
34 if (data & 0x8000)
35 data = data ^ POLY;
36 data = data << 1;
37 }
38 return (u8)(data >> 8);
39 }
40
41 /**
42 * i2c_smbus_pec - Incremental CRC8 over the given input data array
43 * @crc: previous return crc8 value
44 * @p: pointer to data buffer.
45 * @count: number of bytes in data buffer.
46 *
47 * Incremental CRC8 over count bytes in the array pointed to by p
48 */
i2c_smbus_pec(u8 crc,u8 * p,size_t count)49 u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
50 {
51 int i;
52
53 for (i = 0; i < count; i++)
54 crc = crc8((crc ^ p[i]) << 8);
55 return crc;
56 }
57 EXPORT_SYMBOL(i2c_smbus_pec);
58
59 /* Assume a 7-bit address, which is reasonable for SMBus */
i2c_smbus_msg_pec(u8 pec,struct i2c_msg * msg)60 static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
61 {
62 /* The address will be sent first */
63 u8 addr = i2c_8bit_addr_from_msg(msg);
64 pec = i2c_smbus_pec(pec, &addr, 1);
65
66 /* The data buffer follows */
67 return i2c_smbus_pec(pec, msg->buf, msg->len);
68 }
69
70 /* Used for write only transactions */
i2c_smbus_add_pec(struct i2c_msg * msg)71 static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
72 {
73 msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
74 msg->len++;
75 }
76
77 /* Return <0 on CRC error
78 If there was a write before this read (most cases) we need to take the
79 partial CRC from the write part into account.
80 Note that this function does modify the message (we need to decrease the
81 message length to hide the CRC byte from the caller). */
i2c_smbus_check_pec(u8 cpec,struct i2c_msg * msg)82 static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
83 {
84 u8 rpec = msg->buf[--msg->len];
85 cpec = i2c_smbus_msg_pec(cpec, msg);
86
87 if (rpec != cpec) {
88 pr_debug("Bad PEC 0x%02x vs. 0x%02x\n",
89 rpec, cpec);
90 return -EBADMSG;
91 }
92 return 0;
93 }
94
95 /**
96 * i2c_smbus_read_byte - SMBus "receive byte" protocol
97 * @client: Handle to slave device
98 *
99 * This executes the SMBus "receive byte" protocol, returning negative errno
100 * else the byte received from the device.
101 */
i2c_smbus_read_byte(const struct i2c_client * client)102 s32 i2c_smbus_read_byte(const struct i2c_client *client)
103 {
104 union i2c_smbus_data data;
105 int status;
106
107 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
108 I2C_SMBUS_READ, 0,
109 I2C_SMBUS_BYTE, &data);
110 return (status < 0) ? status : data.byte;
111 }
112 EXPORT_SYMBOL(i2c_smbus_read_byte);
113
114 /**
115 * i2c_smbus_write_byte - SMBus "send byte" protocol
116 * @client: Handle to slave device
117 * @value: Byte to be sent
118 *
119 * This executes the SMBus "send byte" protocol, returning negative errno
120 * else zero on success.
121 */
i2c_smbus_write_byte(const struct i2c_client * client,u8 value)122 s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
123 {
124 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
125 I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
126 }
127 EXPORT_SYMBOL(i2c_smbus_write_byte);
128
129 /**
130 * i2c_smbus_read_byte_data - SMBus "read byte" protocol
131 * @client: Handle to slave device
132 * @command: Byte interpreted by slave
133 *
134 * This executes the SMBus "read byte" protocol, returning negative errno
135 * else a data byte received from the device.
136 */
i2c_smbus_read_byte_data(const struct i2c_client * client,u8 command)137 s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
138 {
139 union i2c_smbus_data data;
140 int status;
141
142 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
143 I2C_SMBUS_READ, command,
144 I2C_SMBUS_BYTE_DATA, &data);
145 return (status < 0) ? status : data.byte;
146 }
147 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
148
149 /**
150 * i2c_smbus_write_byte_data - SMBus "write byte" protocol
151 * @client: Handle to slave device
152 * @command: Byte interpreted by slave
153 * @value: Byte being written
154 *
155 * This executes the SMBus "write byte" protocol, returning negative errno
156 * else zero on success.
157 */
i2c_smbus_write_byte_data(const struct i2c_client * client,u8 command,u8 value)158 s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
159 u8 value)
160 {
161 union i2c_smbus_data data;
162 data.byte = value;
163 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
164 I2C_SMBUS_WRITE, command,
165 I2C_SMBUS_BYTE_DATA, &data);
166 }
167 EXPORT_SYMBOL(i2c_smbus_write_byte_data);
168
169 /**
170 * i2c_smbus_read_word_data - SMBus "read word" protocol
171 * @client: Handle to slave device
172 * @command: Byte interpreted by slave
173 *
174 * This executes the SMBus "read word" protocol, returning negative errno
175 * else a 16-bit unsigned "word" received from the device.
176 */
i2c_smbus_read_word_data(const struct i2c_client * client,u8 command)177 s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
178 {
179 union i2c_smbus_data data;
180 int status;
181
182 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
183 I2C_SMBUS_READ, command,
184 I2C_SMBUS_WORD_DATA, &data);
185 return (status < 0) ? status : data.word;
186 }
187 EXPORT_SYMBOL(i2c_smbus_read_word_data);
188
189 /**
190 * i2c_smbus_write_word_data - SMBus "write word" protocol
191 * @client: Handle to slave device
192 * @command: Byte interpreted by slave
193 * @value: 16-bit "word" being written
194 *
195 * This executes the SMBus "write word" protocol, returning negative errno
196 * else zero on success.
197 */
i2c_smbus_write_word_data(const struct i2c_client * client,u8 command,u16 value)198 s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
199 u16 value)
200 {
201 union i2c_smbus_data data;
202 data.word = value;
203 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
204 I2C_SMBUS_WRITE, command,
205 I2C_SMBUS_WORD_DATA, &data);
206 }
207 EXPORT_SYMBOL(i2c_smbus_write_word_data);
208
209 /**
210 * i2c_smbus_read_block_data - SMBus "block read" protocol
211 * @client: Handle to slave device
212 * @command: Byte interpreted by slave
213 * @values: Byte array into which data will be read; big enough to hold
214 * the data returned by the slave. SMBus allows at most 32 bytes.
215 *
216 * This executes the SMBus "block read" protocol, returning negative errno
217 * else the number of data bytes in the slave's response.
218 *
219 * Note that using this function requires that the client's adapter support
220 * the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
221 * support this; its emulation through I2C messaging relies on a specific
222 * mechanism (I2C_M_RECV_LEN) which may not be implemented.
223 */
i2c_smbus_read_block_data(const struct i2c_client * client,u8 command,u8 * values)224 s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
225 u8 *values)
226 {
227 union i2c_smbus_data data;
228 int status;
229
230 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
231 I2C_SMBUS_READ, command,
232 I2C_SMBUS_BLOCK_DATA, &data);
233 if (status)
234 return status;
235
236 memcpy(values, &data.block[1], data.block[0]);
237 return data.block[0];
238 }
239 EXPORT_SYMBOL(i2c_smbus_read_block_data);
240
241 /**
242 * i2c_smbus_write_block_data - SMBus "block write" protocol
243 * @client: Handle to slave device
244 * @command: Byte interpreted by slave
245 * @length: Size of data block; SMBus allows at most 32 bytes
246 * @values: Byte array which will be written.
247 *
248 * This executes the SMBus "block write" protocol, returning negative errno
249 * else zero on success.
250 */
i2c_smbus_write_block_data(const struct i2c_client * client,u8 command,u8 length,const u8 * values)251 s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
252 u8 length, const u8 *values)
253 {
254 union i2c_smbus_data data;
255
256 if (length > I2C_SMBUS_BLOCK_MAX)
257 length = I2C_SMBUS_BLOCK_MAX;
258 data.block[0] = length;
259 memcpy(&data.block[1], values, length);
260 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
261 I2C_SMBUS_WRITE, command,
262 I2C_SMBUS_BLOCK_DATA, &data);
263 }
264 EXPORT_SYMBOL(i2c_smbus_write_block_data);
265
266 /* Returns the number of read bytes */
i2c_smbus_read_i2c_block_data(const struct i2c_client * client,u8 command,u8 length,u8 * values)267 s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
268 u8 length, u8 *values)
269 {
270 union i2c_smbus_data data;
271 int status;
272
273 if (length > I2C_SMBUS_BLOCK_MAX)
274 length = I2C_SMBUS_BLOCK_MAX;
275 data.block[0] = length;
276 status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
277 I2C_SMBUS_READ, command,
278 I2C_SMBUS_I2C_BLOCK_DATA, &data);
279 if (status < 0)
280 return status;
281
282 memcpy(values, &data.block[1], data.block[0]);
283 return data.block[0];
284 }
285 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
286
i2c_smbus_write_i2c_block_data(const struct i2c_client * client,u8 command,u8 length,const u8 * values)287 s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
288 u8 length, const u8 *values)
289 {
290 union i2c_smbus_data data;
291
292 if (length > I2C_SMBUS_BLOCK_MAX)
293 length = I2C_SMBUS_BLOCK_MAX;
294 data.block[0] = length;
295 memcpy(data.block + 1, values, length);
296 return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
297 I2C_SMBUS_WRITE, command,
298 I2C_SMBUS_I2C_BLOCK_DATA, &data);
299 }
300 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
301
i2c_smbus_try_get_dmabuf(struct i2c_msg * msg,u8 init_val)302 static void i2c_smbus_try_get_dmabuf(struct i2c_msg *msg, u8 init_val)
303 {
304 bool is_read = msg->flags & I2C_M_RD;
305 unsigned char *dma_buf;
306
307 dma_buf = kzalloc(I2C_SMBUS_BLOCK_MAX + (is_read ? 2 : 3), GFP_KERNEL);
308 if (!dma_buf)
309 return;
310
311 msg->buf = dma_buf;
312 msg->flags |= I2C_M_DMA_SAFE;
313
314 if (init_val)
315 msg->buf[0] = init_val;
316 }
317
318 /*
319 * Simulate a SMBus command using the I2C protocol.
320 * No checking of parameters is done!
321 */
i2c_smbus_xfer_emulated(struct i2c_adapter * adapter,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)322 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
323 unsigned short flags,
324 char read_write, u8 command, int size,
325 union i2c_smbus_data *data)
326 {
327 /*
328 * So we need to generate a series of msgs. In the case of writing, we
329 * need to use only one message; when reading, we need two. We
330 * initialize most things with sane defaults, to keep the code below
331 * somewhat simpler.
332 */
333 unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
334 unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
335 int nmsgs = read_write == I2C_SMBUS_READ ? 2 : 1;
336 u8 partial_pec = 0;
337 int status;
338 struct i2c_msg msg[2] = {
339 {
340 .addr = addr,
341 .flags = flags,
342 .len = 1,
343 .buf = msgbuf0,
344 }, {
345 .addr = addr,
346 .flags = flags | I2C_M_RD,
347 .len = 0,
348 .buf = msgbuf1,
349 },
350 };
351 bool wants_pec = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
352 && size != I2C_SMBUS_I2C_BLOCK_DATA);
353
354 msgbuf0[0] = command;
355 switch (size) {
356 case I2C_SMBUS_QUICK:
357 msg[0].len = 0;
358 /* Special case: The read/write field is used as data */
359 msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
360 I2C_M_RD : 0);
361 nmsgs = 1;
362 break;
363 case I2C_SMBUS_BYTE:
364 if (read_write == I2C_SMBUS_READ) {
365 /* Special case: only a read! */
366 msg[0].flags = I2C_M_RD | flags;
367 nmsgs = 1;
368 }
369 break;
370 case I2C_SMBUS_BYTE_DATA:
371 if (read_write == I2C_SMBUS_READ)
372 msg[1].len = 1;
373 else {
374 msg[0].len = 2;
375 msgbuf0[1] = data->byte;
376 }
377 break;
378 case I2C_SMBUS_WORD_DATA:
379 if (read_write == I2C_SMBUS_READ)
380 msg[1].len = 2;
381 else {
382 msg[0].len = 3;
383 msgbuf0[1] = data->word & 0xff;
384 msgbuf0[2] = data->word >> 8;
385 }
386 break;
387 case I2C_SMBUS_PROC_CALL:
388 nmsgs = 2; /* Special case */
389 read_write = I2C_SMBUS_READ;
390 msg[0].len = 3;
391 msg[1].len = 2;
392 msgbuf0[1] = data->word & 0xff;
393 msgbuf0[2] = data->word >> 8;
394 break;
395 case I2C_SMBUS_BLOCK_DATA:
396 if (read_write == I2C_SMBUS_READ) {
397 msg[1].flags |= I2C_M_RECV_LEN;
398 msg[1].len = 1; /* block length will be added by
399 the underlying bus driver */
400 i2c_smbus_try_get_dmabuf(&msg[1], 0);
401 } else {
402 msg[0].len = data->block[0] + 2;
403 if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
404 dev_err(&adapter->dev,
405 "Invalid block write size %d\n",
406 data->block[0]);
407 return -EINVAL;
408 }
409
410 i2c_smbus_try_get_dmabuf(&msg[0], command);
411 memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
412 }
413 break;
414 case I2C_SMBUS_BLOCK_PROC_CALL:
415 nmsgs = 2; /* Another special case */
416 read_write = I2C_SMBUS_READ;
417 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
418 dev_err(&adapter->dev,
419 "Invalid block write size %d\n",
420 data->block[0]);
421 return -EINVAL;
422 }
423
424 msg[0].len = data->block[0] + 2;
425 i2c_smbus_try_get_dmabuf(&msg[0], command);
426 memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);
427
428 msg[1].flags |= I2C_M_RECV_LEN;
429 msg[1].len = 1; /* block length will be added by
430 the underlying bus driver */
431 i2c_smbus_try_get_dmabuf(&msg[1], 0);
432 break;
433 case I2C_SMBUS_I2C_BLOCK_DATA:
434 if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
435 dev_err(&adapter->dev, "Invalid block %s size %d\n",
436 read_write == I2C_SMBUS_READ ? "read" : "write",
437 data->block[0]);
438 return -EINVAL;
439 }
440
441 if (read_write == I2C_SMBUS_READ) {
442 msg[1].len = data->block[0];
443 i2c_smbus_try_get_dmabuf(&msg[1], 0);
444 } else {
445 msg[0].len = data->block[0] + 1;
446
447 i2c_smbus_try_get_dmabuf(&msg[0], command);
448 memcpy(msg[0].buf + 1, data->block + 1, data->block[0]);
449 }
450 break;
451 default:
452 dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
453 return -EOPNOTSUPP;
454 }
455
456 if (wants_pec) {
457 /* Compute PEC if first message is a write */
458 if (!(msg[0].flags & I2C_M_RD)) {
459 if (nmsgs == 1) /* Write only */
460 i2c_smbus_add_pec(&msg[0]);
461 else /* Write followed by read */
462 partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
463 }
464 /* Ask for PEC if last message is a read */
465 if (msg[nmsgs - 1].flags & I2C_M_RD)
466 msg[nmsgs - 1].len++;
467 }
468
469 status = __i2c_transfer(adapter, msg, nmsgs);
470 if (status < 0)
471 goto cleanup;
472 if (status != nmsgs) {
473 status = -EIO;
474 goto cleanup;
475 }
476 status = 0;
477
478 /* Check PEC if last message is a read */
479 if (wants_pec && (msg[nmsgs - 1].flags & I2C_M_RD)) {
480 status = i2c_smbus_check_pec(partial_pec, &msg[nmsgs - 1]);
481 if (status < 0)
482 goto cleanup;
483 }
484
485 if (read_write == I2C_SMBUS_READ)
486 switch (size) {
487 case I2C_SMBUS_BYTE:
488 data->byte = msgbuf0[0];
489 break;
490 case I2C_SMBUS_BYTE_DATA:
491 data->byte = msgbuf1[0];
492 break;
493 case I2C_SMBUS_WORD_DATA:
494 case I2C_SMBUS_PROC_CALL:
495 data->word = msgbuf1[0] | (msgbuf1[1] << 8);
496 break;
497 case I2C_SMBUS_I2C_BLOCK_DATA:
498 memcpy(data->block + 1, msg[1].buf, data->block[0]);
499 break;
500 case I2C_SMBUS_BLOCK_DATA:
501 case I2C_SMBUS_BLOCK_PROC_CALL:
502 if (msg[1].buf[0] > I2C_SMBUS_BLOCK_MAX) {
503 dev_err(&adapter->dev,
504 "Invalid block size returned: %d\n",
505 msg[1].buf[0]);
506 status = -EPROTO;
507 goto cleanup;
508 }
509 memcpy(data->block, msg[1].buf, msg[1].buf[0] + 1);
510 break;
511 }
512
513 cleanup:
514 if (msg[0].flags & I2C_M_DMA_SAFE)
515 kfree(msg[0].buf);
516 if (msg[1].flags & I2C_M_DMA_SAFE)
517 kfree(msg[1].buf);
518
519 return status;
520 }
521
522 /**
523 * i2c_smbus_xfer - execute SMBus protocol operations
524 * @adapter: Handle to I2C bus
525 * @addr: Address of SMBus slave on that bus
526 * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
527 * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
528 * @command: Byte interpreted by slave, for protocols which use such bytes
529 * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
530 * @data: Data to be read or written
531 *
532 * This executes an SMBus protocol operation, and returns a negative
533 * errno code else zero on success.
534 */
i2c_smbus_xfer(struct i2c_adapter * adapter,u16 addr,unsigned short flags,char read_write,u8 command,int protocol,union i2c_smbus_data * data)535 s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
536 unsigned short flags, char read_write,
537 u8 command, int protocol, union i2c_smbus_data *data)
538 {
539 s32 res;
540
541 res = __i2c_lock_bus_helper(adapter);
542 if (res)
543 return res;
544
545 res = __i2c_smbus_xfer(adapter, addr, flags, read_write,
546 command, protocol, data);
547 i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT);
548
549 return res;
550 }
551 EXPORT_SYMBOL(i2c_smbus_xfer);
552
__i2c_smbus_xfer(struct i2c_adapter * adapter,u16 addr,unsigned short flags,char read_write,u8 command,int protocol,union i2c_smbus_data * data)553 s32 __i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
554 unsigned short flags, char read_write,
555 u8 command, int protocol, union i2c_smbus_data *data)
556 {
557 int (*xfer_func)(struct i2c_adapter *adap, u16 addr,
558 unsigned short flags, char read_write,
559 u8 command, int size, union i2c_smbus_data *data);
560 unsigned long orig_jiffies;
561 int try;
562 s32 res;
563
564 res = __i2c_check_suspended(adapter);
565 if (res)
566 return res;
567
568 /* If enabled, the following two tracepoints are conditional on
569 * read_write and protocol.
570 */
571 trace_smbus_write(adapter, addr, flags, read_write,
572 command, protocol, data);
573 trace_smbus_read(adapter, addr, flags, read_write,
574 command, protocol);
575
576 flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
577
578 xfer_func = adapter->algo->smbus_xfer;
579 if (i2c_in_atomic_xfer_mode()) {
580 if (adapter->algo->smbus_xfer_atomic)
581 xfer_func = adapter->algo->smbus_xfer_atomic;
582 else if (adapter->algo->master_xfer_atomic)
583 xfer_func = NULL; /* fallback to I2C emulation */
584 }
585
586 if (xfer_func) {
587 /* Retry automatically on arbitration loss */
588 orig_jiffies = jiffies;
589 for (res = 0, try = 0; try <= adapter->retries; try++) {
590 res = xfer_func(adapter, addr, flags, read_write,
591 command, protocol, data);
592 if (res != -EAGAIN)
593 break;
594 if (time_after(jiffies,
595 orig_jiffies + adapter->timeout))
596 break;
597 }
598
599 if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
600 goto trace;
601 /*
602 * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
603 * implement native support for the SMBus operation.
604 */
605 }
606
607 res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
608 command, protocol, data);
609
610 trace:
611 /* If enabled, the reply tracepoint is conditional on read_write. */
612 trace_smbus_reply(adapter, addr, flags, read_write,
613 command, protocol, data, res);
614 trace_smbus_result(adapter, addr, flags, read_write,
615 command, protocol, res);
616
617 return res;
618 }
619 EXPORT_SYMBOL(__i2c_smbus_xfer);
620
621 /**
622 * i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate
623 * @client: Handle to slave device
624 * @command: Byte interpreted by slave
625 * @length: Size of data block; SMBus allows at most I2C_SMBUS_BLOCK_MAX bytes
626 * @values: Byte array into which data will be read; big enough to hold
627 * the data returned by the slave. SMBus allows at most
628 * I2C_SMBUS_BLOCK_MAX bytes.
629 *
630 * This executes the SMBus "block read" protocol if supported by the adapter.
631 * If block read is not supported, it emulates it using either word or byte
632 * read protocols depending on availability.
633 *
634 * The addresses of the I2C slave device that are accessed with this function
635 * must be mapped to a linear region, so that a block read will have the same
636 * effect as a byte read. Before using this function you must double-check
637 * if the I2C slave does support exchanging a block transfer with a byte
638 * transfer.
639 */
i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client * client,u8 command,u8 length,u8 * values)640 s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
641 u8 command, u8 length, u8 *values)
642 {
643 u8 i = 0;
644 int status;
645
646 if (length > I2C_SMBUS_BLOCK_MAX)
647 length = I2C_SMBUS_BLOCK_MAX;
648
649 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
650 return i2c_smbus_read_i2c_block_data(client, command, length, values);
651
652 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA))
653 return -EOPNOTSUPP;
654
655 if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) {
656 while ((i + 2) <= length) {
657 status = i2c_smbus_read_word_data(client, command + i);
658 if (status < 0)
659 return status;
660 values[i] = status & 0xff;
661 values[i + 1] = status >> 8;
662 i += 2;
663 }
664 }
665
666 while (i < length) {
667 status = i2c_smbus_read_byte_data(client, command + i);
668 if (status < 0)
669 return status;
670 values[i] = status;
671 i++;
672 }
673
674 return i;
675 }
676 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data_or_emulated);
677
678 /**
679 * i2c_new_smbus_alert_device - get ara client for SMBus alert support
680 * @adapter: the target adapter
681 * @setup: setup data for the SMBus alert handler
682 * Context: can sleep
683 *
684 * Setup handling of the SMBus alert protocol on a given I2C bus segment.
685 *
686 * Handling can be done either through our IRQ handler, or by the
687 * adapter (from its handler, periodic polling, or whatever).
688 *
689 * This returns the ara client, which should be saved for later use with
690 * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or an
691 * ERRPTR to indicate an error.
692 */
i2c_new_smbus_alert_device(struct i2c_adapter * adapter,struct i2c_smbus_alert_setup * setup)693 struct i2c_client *i2c_new_smbus_alert_device(struct i2c_adapter *adapter,
694 struct i2c_smbus_alert_setup *setup)
695 {
696 struct i2c_board_info ara_board_info = {
697 I2C_BOARD_INFO("smbus_alert", 0x0c),
698 .platform_data = setup,
699 };
700
701 return i2c_new_client_device(adapter, &ara_board_info);
702 }
703 EXPORT_SYMBOL_GPL(i2c_new_smbus_alert_device);
704
705 #if IS_ENABLED(CONFIG_I2C_SMBUS)
i2c_setup_smbus_alert(struct i2c_adapter * adapter)706 int i2c_setup_smbus_alert(struct i2c_adapter *adapter)
707 {
708 struct device *parent = adapter->dev.parent;
709 int irq;
710
711 /* Adapter instantiated without parent, skip the SMBus alert setup */
712 if (!parent)
713 return 0;
714
715 irq = device_property_match_string(parent, "interrupt-names", "smbus_alert");
716 if (irq == -EINVAL || irq == -ENODATA)
717 return 0;
718 else if (irq < 0)
719 return irq;
720
721 return PTR_ERR_OR_ZERO(i2c_new_smbus_alert_device(adapter, NULL));
722 }
723 #endif
724