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22c78d1c WS |
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> | |
3c0a60be | 20 | #include <linux/i2c-smbus.h> |
8a77821e | 21 | #include <linux/slab.h> |
22c78d1c WS |
22 | |
23 | #define CREATE_TRACE_POINTS | |
24 | #include <trace/events/smbus.h> | |
25 | ||
26 | ||
27 | /* The SMBus parts */ | |
28 | ||
29 | #define POLY (0x1070U << 3) | |
30 | static 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 */ | |
43 | static 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 */ | |
53 | static 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 */ | |
64 | static 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). */ | |
75 | static 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 | */ | |
95 | s32 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 | } | |
105 | EXPORT_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 | */ | |
115 | s32 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 | } | |
120 | EXPORT_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 | */ | |
130 | s32 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 | } | |
140 | EXPORT_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 | */ | |
151 | s32 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 | } | |
160 | EXPORT_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 | */ | |
170 | s32 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 | } | |
180 | EXPORT_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 | */ | |
191 | s32 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 | } | |
200 | EXPORT_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 | */ | |
217 | s32 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 | } | |
232 | EXPORT_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 | */ | |
244 | s32 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 | } | |
257 | EXPORT_SYMBOL(i2c_smbus_write_block_data); | |
258 | ||
259 | /* Returns the number of read bytes */ | |
260 | s32 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 | } | |
278 | EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data); | |
279 | ||
280 | s32 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 | } | |
293 | EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data); | |
294 | ||
8a77821e WS |
295 | static 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 | ||
be5b9280 WS |
311 | /* |
312 | * Simulate a SMBus command using the I2C protocol. | |
313 | * No checking of parameters is done! | |
314 | */ | |
22c78d1c WS |
315 | static 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 | { | |
be5b9280 WS |
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 | */ | |
22c78d1c WS |
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 */ | |
8a77821e | 392 | i2c_smbus_try_get_dmabuf(&msg[1], 0); |
22c78d1c WS |
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 | } | |
8a77821e WS |
401 | |
402 | i2c_smbus_try_get_dmabuf(&msg[0], command); | |
22c78d1c | 403 | for (i = 1; i < msg[0].len; i++) |
8a77821e | 404 | msg[0].buf[i] = data->block[i - 1]; |
22c78d1c WS |
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 | } | |
8a77821e | 416 | |
22c78d1c | 417 | msg[0].len = data->block[0] + 2; |
8a77821e | 418 | i2c_smbus_try_get_dmabuf(&msg[0], command); |
22c78d1c | 419 | for (i = 1; i < msg[0].len; i++) |
8a77821e WS |
420 | msg[0].buf[i] = data->block[i - 1]; |
421 | ||
22c78d1c WS |
422 | msg[1].flags |= I2C_M_RECV_LEN; |
423 | msg[1].len = 1; /* block length will be added by | |
424 | the underlying bus driver */ | |
8a77821e | 425 | i2c_smbus_try_get_dmabuf(&msg[1], 0); |
22c78d1c WS |
426 | break; |
427 | case I2C_SMBUS_I2C_BLOCK_DATA: | |
89c6efa6 JC |
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 | ||
22c78d1c WS |
435 | if (read_write == I2C_SMBUS_READ) { |
436 | msg[1].len = data->block[0]; | |
8a77821e | 437 | i2c_smbus_try_get_dmabuf(&msg[1], 0); |
22c78d1c WS |
438 | } else { |
439 | msg[0].len = data->block[0] + 1; | |
8a77821e WS |
440 | |
441 | i2c_smbus_try_get_dmabuf(&msg[0], command); | |
22c78d1c | 442 | for (i = 1; i <= data->block[0]; i++) |
8a77821e | 443 | msg[0].buf[i] = data->block[i]; |
22c78d1c WS |
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 | return status; | |
469 | ||
470 | /* Check PEC if last message is a read */ | |
471 | if (i && (msg[num-1].flags & I2C_M_RD)) { | |
472 | status = i2c_smbus_check_pec(partial_pec, &msg[num-1]); | |
473 | if (status < 0) | |
474 | return status; | |
475 | } | |
476 | ||
477 | if (read_write == I2C_SMBUS_READ) | |
478 | switch (size) { | |
479 | case I2C_SMBUS_BYTE: | |
480 | data->byte = msgbuf0[0]; | |
481 | break; | |
482 | case I2C_SMBUS_BYTE_DATA: | |
483 | data->byte = msgbuf1[0]; | |
484 | break; | |
485 | case I2C_SMBUS_WORD_DATA: | |
486 | case I2C_SMBUS_PROC_CALL: | |
487 | data->word = msgbuf1[0] | (msgbuf1[1] << 8); | |
488 | break; | |
489 | case I2C_SMBUS_I2C_BLOCK_DATA: | |
490 | for (i = 0; i < data->block[0]; i++) | |
8a77821e | 491 | data->block[i + 1] = msg[1].buf[i]; |
22c78d1c WS |
492 | break; |
493 | case I2C_SMBUS_BLOCK_DATA: | |
494 | case I2C_SMBUS_BLOCK_PROC_CALL: | |
8a77821e WS |
495 | for (i = 0; i < msg[1].buf[0] + 1; i++) |
496 | data->block[i] = msg[1].buf[i]; | |
22c78d1c WS |
497 | break; |
498 | } | |
8a77821e WS |
499 | |
500 | if (msg[0].flags & I2C_M_DMA_SAFE) | |
501 | kfree(msg[0].buf); | |
502 | if (msg[1].flags & I2C_M_DMA_SAFE) | |
503 | kfree(msg[1].buf); | |
504 | ||
22c78d1c WS |
505 | return 0; |
506 | } | |
507 | ||
508 | /** | |
509 | * i2c_smbus_xfer - execute SMBus protocol operations | |
510 | * @adapter: Handle to I2C bus | |
511 | * @addr: Address of SMBus slave on that bus | |
512 | * @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC) | |
513 | * @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE | |
514 | * @command: Byte interpreted by slave, for protocols which use such bytes | |
515 | * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL | |
516 | * @data: Data to be read or written | |
517 | * | |
518 | * This executes an SMBus protocol operation, and returns a negative | |
519 | * errno code else zero on success. | |
520 | */ | |
521 | s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, | |
522 | char read_write, u8 command, int protocol, | |
523 | union i2c_smbus_data *data) | |
524 | { | |
525 | unsigned long orig_jiffies; | |
526 | int try; | |
527 | s32 res; | |
528 | ||
529 | /* If enabled, the following two tracepoints are conditional on | |
530 | * read_write and protocol. | |
531 | */ | |
532 | trace_smbus_write(adapter, addr, flags, read_write, | |
533 | command, protocol, data); | |
534 | trace_smbus_read(adapter, addr, flags, read_write, | |
535 | command, protocol); | |
536 | ||
537 | flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB; | |
538 | ||
539 | if (adapter->algo->smbus_xfer) { | |
540 | i2c_lock_bus(adapter, I2C_LOCK_SEGMENT); | |
541 | ||
542 | /* Retry automatically on arbitration loss */ | |
543 | orig_jiffies = jiffies; | |
544 | for (res = 0, try = 0; try <= adapter->retries; try++) { | |
545 | res = adapter->algo->smbus_xfer(adapter, addr, flags, | |
546 | read_write, command, | |
547 | protocol, data); | |
548 | if (res != -EAGAIN) | |
549 | break; | |
550 | if (time_after(jiffies, | |
551 | orig_jiffies + adapter->timeout)) | |
552 | break; | |
553 | } | |
554 | i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT); | |
555 | ||
556 | if (res != -EOPNOTSUPP || !adapter->algo->master_xfer) | |
557 | goto trace; | |
558 | /* | |
559 | * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't | |
560 | * implement native support for the SMBus operation. | |
561 | */ | |
562 | } | |
563 | ||
564 | res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, | |
565 | command, protocol, data); | |
566 | ||
567 | trace: | |
568 | /* If enabled, the reply tracepoint is conditional on read_write. */ | |
569 | trace_smbus_reply(adapter, addr, flags, read_write, | |
570 | command, protocol, data); | |
571 | trace_smbus_result(adapter, addr, flags, read_write, | |
572 | command, protocol, res); | |
573 | ||
574 | return res; | |
575 | } | |
576 | EXPORT_SYMBOL(i2c_smbus_xfer); | |
577 | ||
578 | /** | |
579 | * i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate | |
580 | * @client: Handle to slave device | |
581 | * @command: Byte interpreted by slave | |
582 | * @length: Size of data block; SMBus allows at most I2C_SMBUS_BLOCK_MAX bytes | |
583 | * @values: Byte array into which data will be read; big enough to hold | |
584 | * the data returned by the slave. SMBus allows at most | |
585 | * I2C_SMBUS_BLOCK_MAX bytes. | |
586 | * | |
587 | * This executes the SMBus "block read" protocol if supported by the adapter. | |
588 | * If block read is not supported, it emulates it using either word or byte | |
589 | * read protocols depending on availability. | |
590 | * | |
591 | * The addresses of the I2C slave device that are accessed with this function | |
592 | * must be mapped to a linear region, so that a block read will have the same | |
593 | * effect as a byte read. Before using this function you must double-check | |
594 | * if the I2C slave does support exchanging a block transfer with a byte | |
595 | * transfer. | |
596 | */ | |
597 | s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client, | |
598 | u8 command, u8 length, u8 *values) | |
599 | { | |
600 | u8 i = 0; | |
601 | int status; | |
602 | ||
603 | if (length > I2C_SMBUS_BLOCK_MAX) | |
604 | length = I2C_SMBUS_BLOCK_MAX; | |
605 | ||
606 | if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) | |
607 | return i2c_smbus_read_i2c_block_data(client, command, length, values); | |
608 | ||
609 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) | |
610 | return -EOPNOTSUPP; | |
611 | ||
612 | if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) { | |
613 | while ((i + 2) <= length) { | |
614 | status = i2c_smbus_read_word_data(client, command + i); | |
615 | if (status < 0) | |
616 | return status; | |
617 | values[i] = status & 0xff; | |
618 | values[i + 1] = status >> 8; | |
619 | i += 2; | |
620 | } | |
621 | } | |
622 | ||
623 | while (i < length) { | |
624 | status = i2c_smbus_read_byte_data(client, command + i); | |
625 | if (status < 0) | |
626 | return status; | |
627 | values[i] = status; | |
628 | i++; | |
629 | } | |
630 | ||
631 | return i; | |
632 | } | |
633 | EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data_or_emulated); | |
3c0a60be PR |
634 | |
635 | /** | |
636 | * i2c_setup_smbus_alert - Setup SMBus alert support | |
637 | * @adapter: the target adapter | |
638 | * @setup: setup data for the SMBus alert handler | |
639 | * Context: can sleep | |
640 | * | |
641 | * Setup handling of the SMBus alert protocol on a given I2C bus segment. | |
642 | * | |
643 | * Handling can be done either through our IRQ handler, or by the | |
644 | * adapter (from its handler, periodic polling, or whatever). | |
645 | * | |
646 | * NOTE that if we manage the IRQ, we *MUST* know if it's level or | |
647 | * edge triggered in order to hand it to the workqueue correctly. | |
648 | * If triggering the alert seems to wedge the system, you probably | |
649 | * should have said it's level triggered. | |
650 | * | |
651 | * This returns the ara client, which should be saved for later use with | |
652 | * i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL | |
653 | * to indicate an error. | |
654 | */ | |
655 | struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter, | |
656 | struct i2c_smbus_alert_setup *setup) | |
657 | { | |
658 | struct i2c_board_info ara_board_info = { | |
659 | I2C_BOARD_INFO("smbus_alert", 0x0c), | |
660 | .platform_data = setup, | |
661 | }; | |
662 | ||
663 | return i2c_new_device(adapter, &ara_board_info); | |
664 | } | |
665 | EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert); | |
69d17246 PR |
666 | |
667 | #if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF) | |
668 | int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter) | |
669 | { | |
670 | struct i2c_client *client; | |
671 | int irq; | |
672 | ||
673 | irq = of_property_match_string(adapter->dev.of_node, "interrupt-names", | |
674 | "smbus_alert"); | |
675 | if (irq == -EINVAL || irq == -ENODATA) | |
676 | return 0; | |
677 | else if (irq < 0) | |
678 | return irq; | |
679 | ||
680 | client = i2c_setup_smbus_alert(adapter, NULL); | |
681 | if (!client) | |
682 | return -ENODEV; | |
683 | ||
684 | return 0; | |
685 | } | |
686 | EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert); | |
687 | #endif |