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) |
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 | */ |
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(data: (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 */ |
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 */ |
71 | static inline void i2c_smbus_add_pec(struct i2c_msg *msg) |
72 | { |
73 | msg->buf[msg->len] = i2c_smbus_msg_pec(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). */ |
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(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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
108 | I2C_SMBUS_READ, command: 0, |
109 | I2C_SMBUS_BYTE, data: &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 | */ |
122 | s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value) |
123 | { |
124 | return i2c_smbus_xfer(adapter: client->adapter, addr: client->addr, flags: client->flags, |
125 | I2C_SMBUS_WRITE, command: 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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
143 | I2C_SMBUS_READ, command, |
144 | I2C_SMBUS_BYTE_DATA, 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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
164 | I2C_SMBUS_WRITE, command, |
165 | I2C_SMBUS_BYTE_DATA, 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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
183 | I2C_SMBUS_READ, command, |
184 | I2C_SMBUS_WORD_DATA, 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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
204 | I2C_SMBUS_WRITE, command, |
205 | I2C_SMBUS_WORD_DATA, 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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
231 | I2C_SMBUS_READ, command, |
232 | I2C_SMBUS_BLOCK_DATA, 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 | */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
261 | I2C_SMBUS_WRITE, command, |
262 | I2C_SMBUS_BLOCK_DATA, data: &data); |
263 | } |
264 | EXPORT_SYMBOL(i2c_smbus_write_block_data); |
265 | |
266 | /* Returns the number of read bytes */ |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
277 | I2C_SMBUS_READ, command, |
278 | I2C_SMBUS_I2C_BLOCK_DATA, 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 | |
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(adapter: client->adapter, addr: client->addr, flags: client->flags, |
297 | I2C_SMBUS_WRITE, command, |
298 | I2C_SMBUS_I2C_BLOCK_DATA, data: &data); |
299 | } |
300 | EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data); |
301 | |
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 | */ |
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: &msg[1], init_val: 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: &msg[0], init_val: 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: &msg[0], init_val: 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: &msg[1], init_val: 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: &msg[1], init_val: 0); |
444 | } else { |
445 | msg[0].len = data->block[0] + 1; |
446 | |
447 | i2c_smbus_try_get_dmabuf(msg: &msg[0], init_val: 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: &msg[0]); |
461 | else /* Write followed by read */ |
462 | partial_pec = i2c_smbus_msg_pec(pec: 0, msg: &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(adap: adapter, msgs: msg, num: 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(cpec: partial_pec, msg: &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(objp: msg[0].buf); |
516 | if (msg[1].flags & I2C_M_DMA_SAFE) |
517 | kfree(objp: 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 | */ |
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(adap: 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 | |
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(adap: 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(adap: adapter, addr, flags, read_write, |
572 | command, protocol, data); |
573 | trace_smbus_read(adap: 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, size: protocol, data); |
609 | |
610 | trace: |
611 | /* If enabled, the reply tracepoint is conditional on read_write. */ |
612 | trace_smbus_reply(adap: adapter, addr, flags, read_write, |
613 | command, protocol, data, res); |
614 | trace_smbus_result(adap: 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 | */ |
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(adap: 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(adap: client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) |
653 | return -EOPNOTSUPP; |
654 | |
655 | if (i2c_check_functionality(adap: 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 | */ |
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(adap: adapter, info: &ara_board_info); |
702 | } |
703 | EXPORT_SYMBOL_GPL(i2c_new_smbus_alert_device); |
704 | |
705 | #if IS_ENABLED(CONFIG_I2C_SMBUS) |
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(dev: parent, propname: "interrupt-names" , string: "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(ptr: i2c_new_smbus_alert_device(adapter, NULL)); |
722 | } |
723 | #endif |
724 | |