1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * i2c-algo-bit.c: i2c driver algorithms for bit-shift adapters |
4 | * |
5 | * Copyright (C) 1995-2000 Simon G. Vogl |
6 | * |
7 | * With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki |
8 | * <kmalkki@cc.hut.fi> and Jean Delvare <jdelvare@suse.de> |
9 | */ |
10 | |
11 | #include <linux/kernel.h> |
12 | #include <linux/module.h> |
13 | #include <linux/delay.h> |
14 | #include <linux/errno.h> |
15 | #include <linux/sched.h> |
16 | #include <linux/i2c.h> |
17 | #include <linux/i2c-algo-bit.h> |
18 | |
19 | |
20 | /* ----- global defines ----------------------------------------------- */ |
21 | |
22 | #ifdef DEBUG |
23 | #define bit_dbg(level, dev, format, args...) \ |
24 | do { \ |
25 | if (i2c_debug >= level) \ |
26 | dev_dbg(dev, format, ##args); \ |
27 | } while (0) |
28 | #else |
29 | #define bit_dbg(level, dev, format, args...) \ |
30 | do {} while (0) |
31 | #endif /* DEBUG */ |
32 | |
33 | /* ----- global variables --------------------------------------------- */ |
34 | |
35 | static int bit_test; /* see if the line-setting functions work */ |
36 | module_param(bit_test, int, S_IRUGO); |
37 | MODULE_PARM_DESC(bit_test, "lines testing - 0 off; 1 report; 2 fail if stuck" ); |
38 | |
39 | #ifdef DEBUG |
40 | static int i2c_debug = 1; |
41 | module_param(i2c_debug, int, S_IRUGO | S_IWUSR); |
42 | MODULE_PARM_DESC(i2c_debug, |
43 | "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose" ); |
44 | #endif |
45 | |
46 | /* --- setting states on the bus with the right timing: --------------- */ |
47 | |
48 | #define setsda(adap, val) adap->setsda(adap->data, val) |
49 | #define setscl(adap, val) adap->setscl(adap->data, val) |
50 | #define getsda(adap) adap->getsda(adap->data) |
51 | #define getscl(adap) adap->getscl(adap->data) |
52 | |
53 | static inline void sdalo(struct i2c_algo_bit_data *adap) |
54 | { |
55 | setsda(adap, 0); |
56 | udelay((adap->udelay + 1) / 2); |
57 | } |
58 | |
59 | static inline void sdahi(struct i2c_algo_bit_data *adap) |
60 | { |
61 | setsda(adap, 1); |
62 | udelay((adap->udelay + 1) / 2); |
63 | } |
64 | |
65 | static inline void scllo(struct i2c_algo_bit_data *adap) |
66 | { |
67 | setscl(adap, 0); |
68 | udelay(adap->udelay / 2); |
69 | } |
70 | |
71 | /* |
72 | * Raise scl line, and do checking for delays. This is necessary for slower |
73 | * devices. |
74 | */ |
75 | static int sclhi(struct i2c_algo_bit_data *adap) |
76 | { |
77 | unsigned long start; |
78 | |
79 | setscl(adap, 1); |
80 | |
81 | /* Not all adapters have scl sense line... */ |
82 | if (!adap->getscl) |
83 | goto done; |
84 | |
85 | start = jiffies; |
86 | while (!getscl(adap)) { |
87 | /* This hw knows how to read the clock line, so we wait |
88 | * until it actually gets high. This is safer as some |
89 | * chips may hold it low ("clock stretching") while they |
90 | * are processing data internally. |
91 | */ |
92 | if (time_after(jiffies, start + adap->timeout)) { |
93 | /* Test one last time, as we may have been preempted |
94 | * between last check and timeout test. |
95 | */ |
96 | if (getscl(adap)) |
97 | break; |
98 | return -ETIMEDOUT; |
99 | } |
100 | cpu_relax(); |
101 | } |
102 | #ifdef DEBUG |
103 | if (jiffies != start && i2c_debug >= 3) |
104 | pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go high\n" , |
105 | jiffies - start); |
106 | #endif |
107 | |
108 | done: |
109 | udelay(adap->udelay); |
110 | return 0; |
111 | } |
112 | |
113 | |
114 | /* --- other auxiliary functions -------------------------------------- */ |
115 | static void i2c_start(struct i2c_algo_bit_data *adap) |
116 | { |
117 | /* assert: scl, sda are high */ |
118 | setsda(adap, 0); |
119 | udelay(adap->udelay); |
120 | scllo(adap); |
121 | } |
122 | |
123 | static void i2c_repstart(struct i2c_algo_bit_data *adap) |
124 | { |
125 | /* assert: scl is low */ |
126 | sdahi(adap); |
127 | sclhi(adap); |
128 | setsda(adap, 0); |
129 | udelay(adap->udelay); |
130 | scllo(adap); |
131 | } |
132 | |
133 | |
134 | static void i2c_stop(struct i2c_algo_bit_data *adap) |
135 | { |
136 | /* assert: scl is low */ |
137 | sdalo(adap); |
138 | sclhi(adap); |
139 | setsda(adap, 1); |
140 | udelay(adap->udelay); |
141 | } |
142 | |
143 | |
144 | |
145 | /* send a byte without start cond., look for arbitration, |
146 | check ackn. from slave */ |
147 | /* returns: |
148 | * 1 if the device acknowledged |
149 | * 0 if the device did not ack |
150 | * -ETIMEDOUT if an error occurred (while raising the scl line) |
151 | */ |
152 | static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c) |
153 | { |
154 | int i; |
155 | int sb; |
156 | int ack; |
157 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
158 | |
159 | /* assert: scl is low */ |
160 | for (i = 7; i >= 0; i--) { |
161 | sb = (c >> i) & 1; |
162 | setsda(adap, sb); |
163 | udelay((adap->udelay + 1) / 2); |
164 | if (sclhi(adap) < 0) { /* timed out */ |
165 | bit_dbg(1, &i2c_adap->dev, |
166 | "i2c_outb: 0x%02x, timeout at bit #%d\n" , |
167 | (int)c, i); |
168 | return -ETIMEDOUT; |
169 | } |
170 | /* FIXME do arbitration here: |
171 | * if (sb && !getsda(adap)) -> ouch! Get out of here. |
172 | * |
173 | * Report a unique code, so higher level code can retry |
174 | * the whole (combined) message and *NOT* issue STOP. |
175 | */ |
176 | scllo(adap); |
177 | } |
178 | sdahi(adap); |
179 | if (sclhi(adap) < 0) { /* timeout */ |
180 | bit_dbg(1, &i2c_adap->dev, |
181 | "i2c_outb: 0x%02x, timeout at ack\n" , (int)c); |
182 | return -ETIMEDOUT; |
183 | } |
184 | |
185 | /* read ack: SDA should be pulled down by slave, or it may |
186 | * NAK (usually to report problems with the data we wrote). |
187 | * Always report ACK if SDA is write-only. |
188 | */ |
189 | ack = !adap->getsda || !getsda(adap); /* ack: sda is pulled low -> success */ |
190 | bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n" , (int)c, |
191 | ack ? "A" : "NA" ); |
192 | |
193 | scllo(adap); |
194 | return ack; |
195 | /* assert: scl is low (sda undef) */ |
196 | } |
197 | |
198 | |
199 | static int i2c_inb(struct i2c_adapter *i2c_adap) |
200 | { |
201 | /* read byte via i2c port, without start/stop sequence */ |
202 | /* acknowledge is sent in i2c_read. */ |
203 | int i; |
204 | unsigned char indata = 0; |
205 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
206 | |
207 | /* assert: scl is low */ |
208 | sdahi(adap); |
209 | for (i = 0; i < 8; i++) { |
210 | if (sclhi(adap) < 0) { /* timeout */ |
211 | bit_dbg(1, &i2c_adap->dev, |
212 | "i2c_inb: timeout at bit #%d\n" , |
213 | 7 - i); |
214 | return -ETIMEDOUT; |
215 | } |
216 | indata *= 2; |
217 | if (getsda(adap)) |
218 | indata |= 0x01; |
219 | setscl(adap, 0); |
220 | udelay(i == 7 ? adap->udelay / 2 : adap->udelay); |
221 | } |
222 | /* assert: scl is low */ |
223 | return indata; |
224 | } |
225 | |
226 | /* |
227 | * Sanity check for the adapter hardware - check the reaction of |
228 | * the bus lines only if it seems to be idle. |
229 | */ |
230 | static int test_bus(struct i2c_adapter *i2c_adap) |
231 | { |
232 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
233 | const char *name = i2c_adap->name; |
234 | int scl, sda, ret; |
235 | |
236 | if (adap->pre_xfer) { |
237 | ret = adap->pre_xfer(i2c_adap); |
238 | if (ret < 0) |
239 | return -ENODEV; |
240 | } |
241 | |
242 | if (adap->getsda == NULL) |
243 | pr_info("%s: SDA is write-only, testing not possible\n" , name); |
244 | if (adap->getscl == NULL) |
245 | pr_info("%s: SCL is write-only, testing not possible\n" , name); |
246 | |
247 | sda = adap->getsda ? getsda(adap) : 1; |
248 | scl = adap->getscl ? getscl(adap) : 1; |
249 | if (!scl || !sda) { |
250 | pr_warn("%s: bus seems to be busy (scl=%d, sda=%d)\n" , name, scl, sda); |
251 | goto bailout; |
252 | } |
253 | |
254 | sdalo(adap); |
255 | if (adap->getsda && getsda(adap)) { |
256 | pr_warn("%s: SDA stuck high!\n" , name); |
257 | goto bailout; |
258 | } |
259 | if (adap->getscl && !getscl(adap)) { |
260 | pr_warn("%s: SCL unexpected low while pulling SDA low!\n" , name); |
261 | goto bailout; |
262 | } |
263 | |
264 | sdahi(adap); |
265 | if (adap->getsda && !getsda(adap)) { |
266 | pr_warn("%s: SDA stuck low!\n" , name); |
267 | goto bailout; |
268 | } |
269 | if (adap->getscl && !getscl(adap)) { |
270 | pr_warn("%s: SCL unexpected low while pulling SDA high!\n" , name); |
271 | goto bailout; |
272 | } |
273 | |
274 | scllo(adap); |
275 | if (adap->getscl && getscl(adap)) { |
276 | pr_warn("%s: SCL stuck high!\n" , name); |
277 | goto bailout; |
278 | } |
279 | if (adap->getsda && !getsda(adap)) { |
280 | pr_warn("%s: SDA unexpected low while pulling SCL low!\n" , name); |
281 | goto bailout; |
282 | } |
283 | |
284 | sclhi(adap); |
285 | if (adap->getscl && !getscl(adap)) { |
286 | pr_warn("%s: SCL stuck low!\n" , name); |
287 | goto bailout; |
288 | } |
289 | if (adap->getsda && !getsda(adap)) { |
290 | pr_warn("%s: SDA unexpected low while pulling SCL high!\n" , name); |
291 | goto bailout; |
292 | } |
293 | |
294 | if (adap->post_xfer) |
295 | adap->post_xfer(i2c_adap); |
296 | |
297 | pr_info("%s: Test OK\n" , name); |
298 | return 0; |
299 | bailout: |
300 | sdahi(adap); |
301 | sclhi(adap); |
302 | |
303 | if (adap->post_xfer) |
304 | adap->post_xfer(i2c_adap); |
305 | |
306 | return -ENODEV; |
307 | } |
308 | |
309 | /* ----- Utility functions |
310 | */ |
311 | |
312 | /* try_address tries to contact a chip for a number of |
313 | * times before it gives up. |
314 | * return values: |
315 | * 1 chip answered |
316 | * 0 chip did not answer |
317 | * -x transmission error |
318 | */ |
319 | static int try_address(struct i2c_adapter *i2c_adap, |
320 | unsigned char addr, int retries) |
321 | { |
322 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
323 | int i, ret = 0; |
324 | |
325 | for (i = 0; i <= retries; i++) { |
326 | ret = i2c_outb(i2c_adap, c: addr); |
327 | if (ret == 1 || i == retries) |
328 | break; |
329 | bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n" ); |
330 | i2c_stop(adap); |
331 | udelay(adap->udelay); |
332 | yield(); |
333 | bit_dbg(3, &i2c_adap->dev, "emitting start condition\n" ); |
334 | i2c_start(adap); |
335 | } |
336 | if (i && ret) |
337 | bit_dbg(1, &i2c_adap->dev, |
338 | "Used %d tries to %s client at 0x%02x: %s\n" , i + 1, |
339 | addr & 1 ? "read from" : "write to" , addr >> 1, |
340 | ret == 1 ? "success" : "failed, timeout?" ); |
341 | return ret; |
342 | } |
343 | |
344 | static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) |
345 | { |
346 | const unsigned char *temp = msg->buf; |
347 | int count = msg->len; |
348 | unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK; |
349 | int retval; |
350 | int wrcount = 0; |
351 | |
352 | while (count > 0) { |
353 | retval = i2c_outb(i2c_adap, c: *temp); |
354 | |
355 | /* OK/ACK; or ignored NAK */ |
356 | if ((retval > 0) || (nak_ok && (retval == 0))) { |
357 | count--; |
358 | temp++; |
359 | wrcount++; |
360 | |
361 | /* A slave NAKing the master means the slave didn't like |
362 | * something about the data it saw. For example, maybe |
363 | * the SMBus PEC was wrong. |
364 | */ |
365 | } else if (retval == 0) { |
366 | dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n" ); |
367 | return -EIO; |
368 | |
369 | /* Timeout; or (someday) lost arbitration |
370 | * |
371 | * FIXME Lost ARB implies retrying the transaction from |
372 | * the first message, after the "winning" master issues |
373 | * its STOP. As a rule, upper layer code has no reason |
374 | * to know or care about this ... it is *NOT* an error. |
375 | */ |
376 | } else { |
377 | dev_err(&i2c_adap->dev, "sendbytes: error %d\n" , |
378 | retval); |
379 | return retval; |
380 | } |
381 | } |
382 | return wrcount; |
383 | } |
384 | |
385 | static int acknak(struct i2c_adapter *i2c_adap, int is_ack) |
386 | { |
387 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
388 | |
389 | /* assert: sda is high */ |
390 | if (is_ack) /* send ack */ |
391 | setsda(adap, 0); |
392 | udelay((adap->udelay + 1) / 2); |
393 | if (sclhi(adap) < 0) { /* timeout */ |
394 | dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n" ); |
395 | return -ETIMEDOUT; |
396 | } |
397 | scllo(adap); |
398 | return 0; |
399 | } |
400 | |
401 | static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) |
402 | { |
403 | int inval; |
404 | int rdcount = 0; /* counts bytes read */ |
405 | unsigned char *temp = msg->buf; |
406 | int count = msg->len; |
407 | const unsigned flags = msg->flags; |
408 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
409 | |
410 | if (!adap->getsda) |
411 | return -EOPNOTSUPP; |
412 | |
413 | while (count > 0) { |
414 | inval = i2c_inb(i2c_adap); |
415 | if (inval >= 0) { |
416 | *temp = inval; |
417 | rdcount++; |
418 | } else { /* read timed out */ |
419 | break; |
420 | } |
421 | |
422 | temp++; |
423 | count--; |
424 | |
425 | /* Some SMBus transactions require that we receive the |
426 | transaction length as the first read byte. */ |
427 | if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) { |
428 | if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) { |
429 | if (!(flags & I2C_M_NO_RD_ACK)) |
430 | acknak(i2c_adap, is_ack: 0); |
431 | dev_err(&i2c_adap->dev, |
432 | "readbytes: invalid block length (%d)\n" , |
433 | inval); |
434 | return -EPROTO; |
435 | } |
436 | /* The original count value accounts for the extra |
437 | bytes, that is, either 1 for a regular transaction, |
438 | or 2 for a PEC transaction. */ |
439 | count += inval; |
440 | msg->len += inval; |
441 | } |
442 | |
443 | bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n" , |
444 | inval, |
445 | (flags & I2C_M_NO_RD_ACK) |
446 | ? "(no ack/nak)" |
447 | : (count ? "A" : "NA" )); |
448 | |
449 | if (!(flags & I2C_M_NO_RD_ACK)) { |
450 | inval = acknak(i2c_adap, is_ack: count); |
451 | if (inval < 0) |
452 | return inval; |
453 | } |
454 | } |
455 | return rdcount; |
456 | } |
457 | |
458 | /* doAddress initiates the transfer by generating the start condition (in |
459 | * try_address) and transmits the address in the necessary format to handle |
460 | * reads, writes as well as 10bit-addresses. |
461 | * returns: |
462 | * 0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set |
463 | * -x an error occurred (like: -ENXIO if the device did not answer, or |
464 | * -ETIMEDOUT, for example if the lines are stuck...) |
465 | */ |
466 | static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg) |
467 | { |
468 | unsigned short flags = msg->flags; |
469 | unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK; |
470 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
471 | |
472 | unsigned char addr; |
473 | int ret, retries; |
474 | |
475 | retries = nak_ok ? 0 : i2c_adap->retries; |
476 | |
477 | if (flags & I2C_M_TEN) { |
478 | /* a ten bit address */ |
479 | addr = 0xf0 | ((msg->addr >> 7) & 0x06); |
480 | bit_dbg(2, &i2c_adap->dev, "addr0: %d\n" , addr); |
481 | /* try extended address code...*/ |
482 | ret = try_address(i2c_adap, addr, retries); |
483 | if ((ret != 1) && !nak_ok) { |
484 | dev_err(&i2c_adap->dev, |
485 | "died at extended address code\n" ); |
486 | return -ENXIO; |
487 | } |
488 | /* the remaining 8 bit address */ |
489 | ret = i2c_outb(i2c_adap, c: msg->addr & 0xff); |
490 | if ((ret != 1) && !nak_ok) { |
491 | /* the chip did not ack / xmission error occurred */ |
492 | dev_err(&i2c_adap->dev, "died at 2nd address code\n" ); |
493 | return -ENXIO; |
494 | } |
495 | if (flags & I2C_M_RD) { |
496 | bit_dbg(3, &i2c_adap->dev, |
497 | "emitting repeated start condition\n" ); |
498 | i2c_repstart(adap); |
499 | /* okay, now switch into reading mode */ |
500 | addr |= 0x01; |
501 | ret = try_address(i2c_adap, addr, retries); |
502 | if ((ret != 1) && !nak_ok) { |
503 | dev_err(&i2c_adap->dev, |
504 | "died at repeated address code\n" ); |
505 | return -EIO; |
506 | } |
507 | } |
508 | } else { /* normal 7bit address */ |
509 | addr = i2c_8bit_addr_from_msg(msg); |
510 | if (flags & I2C_M_REV_DIR_ADDR) |
511 | addr ^= 1; |
512 | ret = try_address(i2c_adap, addr, retries); |
513 | if ((ret != 1) && !nak_ok) |
514 | return -ENXIO; |
515 | } |
516 | |
517 | return 0; |
518 | } |
519 | |
520 | static int bit_xfer(struct i2c_adapter *i2c_adap, |
521 | struct i2c_msg msgs[], int num) |
522 | { |
523 | struct i2c_msg *pmsg; |
524 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
525 | int i, ret; |
526 | unsigned short nak_ok; |
527 | |
528 | if (adap->pre_xfer) { |
529 | ret = adap->pre_xfer(i2c_adap); |
530 | if (ret < 0) |
531 | return ret; |
532 | } |
533 | |
534 | bit_dbg(3, &i2c_adap->dev, "emitting start condition\n" ); |
535 | i2c_start(adap); |
536 | for (i = 0; i < num; i++) { |
537 | pmsg = &msgs[i]; |
538 | nak_ok = pmsg->flags & I2C_M_IGNORE_NAK; |
539 | if (!(pmsg->flags & I2C_M_NOSTART)) { |
540 | if (i) { |
541 | if (msgs[i - 1].flags & I2C_M_STOP) { |
542 | bit_dbg(3, &i2c_adap->dev, |
543 | "emitting enforced stop/start condition\n" ); |
544 | i2c_stop(adap); |
545 | i2c_start(adap); |
546 | } else { |
547 | bit_dbg(3, &i2c_adap->dev, |
548 | "emitting repeated start condition\n" ); |
549 | i2c_repstart(adap); |
550 | } |
551 | } |
552 | ret = bit_doAddress(i2c_adap, msg: pmsg); |
553 | if ((ret != 0) && !nak_ok) { |
554 | bit_dbg(1, &i2c_adap->dev, |
555 | "NAK from device addr 0x%02x msg #%d\n" , |
556 | msgs[i].addr, i); |
557 | goto bailout; |
558 | } |
559 | } |
560 | if (pmsg->flags & I2C_M_RD) { |
561 | /* read bytes into buffer*/ |
562 | ret = readbytes(i2c_adap, msg: pmsg); |
563 | if (ret >= 1) |
564 | bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n" , |
565 | ret, ret == 1 ? "" : "s" ); |
566 | if (ret < pmsg->len) { |
567 | if (ret >= 0) |
568 | ret = -EIO; |
569 | goto bailout; |
570 | } |
571 | } else { |
572 | /* write bytes from buffer */ |
573 | ret = sendbytes(i2c_adap, msg: pmsg); |
574 | if (ret >= 1) |
575 | bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n" , |
576 | ret, ret == 1 ? "" : "s" ); |
577 | if (ret < pmsg->len) { |
578 | if (ret >= 0) |
579 | ret = -EIO; |
580 | goto bailout; |
581 | } |
582 | } |
583 | } |
584 | ret = i; |
585 | |
586 | bailout: |
587 | bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n" ); |
588 | i2c_stop(adap); |
589 | |
590 | if (adap->post_xfer) |
591 | adap->post_xfer(i2c_adap); |
592 | return ret; |
593 | } |
594 | |
595 | /* |
596 | * We print a warning when we are not flagged to support atomic transfers but |
597 | * will try anyhow. That's what the I2C core would do as well. Sadly, we can't |
598 | * modify the algorithm struct at probe time because this struct is exported |
599 | * 'const'. |
600 | */ |
601 | static int bit_xfer_atomic(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[], |
602 | int num) |
603 | { |
604 | struct i2c_algo_bit_data *adap = i2c_adap->algo_data; |
605 | |
606 | if (!adap->can_do_atomic) |
607 | dev_warn(&i2c_adap->dev, "not flagged for atomic transfers\n" ); |
608 | |
609 | return bit_xfer(i2c_adap, msgs, num); |
610 | } |
611 | |
612 | static u32 bit_func(struct i2c_adapter *adap) |
613 | { |
614 | return I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL_ALL | |
615 | I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING; |
616 | } |
617 | |
618 | |
619 | /* -----exported algorithm data: ------------------------------------- */ |
620 | |
621 | const struct i2c_algorithm i2c_bit_algo = { |
622 | .master_xfer = bit_xfer, |
623 | .master_xfer_atomic = bit_xfer_atomic, |
624 | .functionality = bit_func, |
625 | }; |
626 | EXPORT_SYMBOL(i2c_bit_algo); |
627 | |
628 | static const struct i2c_adapter_quirks i2c_bit_quirk_no_clk_stretch = { |
629 | .flags = I2C_AQ_NO_CLK_STRETCH, |
630 | }; |
631 | |
632 | /* |
633 | * registering functions to load algorithms at runtime |
634 | */ |
635 | static int __i2c_bit_add_bus(struct i2c_adapter *adap, |
636 | int (*add_adapter)(struct i2c_adapter *)) |
637 | { |
638 | struct i2c_algo_bit_data *bit_adap = adap->algo_data; |
639 | int ret; |
640 | |
641 | if (bit_test) { |
642 | ret = test_bus(i2c_adap: adap); |
643 | if (bit_test >= 2 && ret < 0) |
644 | return -ENODEV; |
645 | } |
646 | |
647 | /* register new adapter to i2c module... */ |
648 | adap->algo = &i2c_bit_algo; |
649 | adap->retries = 3; |
650 | if (bit_adap->getscl == NULL) |
651 | adap->quirks = &i2c_bit_quirk_no_clk_stretch; |
652 | |
653 | /* |
654 | * We tried forcing SCL/SDA to an initial state here. But that caused a |
655 | * regression, sadly. Check Bugzilla #200045 for details. |
656 | */ |
657 | |
658 | ret = add_adapter(adap); |
659 | if (ret < 0) |
660 | return ret; |
661 | |
662 | if (bit_adap->getsda == NULL) |
663 | dev_warn(&adap->dev, "Not I2C compliant: can't read SDA\n" ); |
664 | |
665 | if (bit_adap->getscl == NULL) |
666 | dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n" ); |
667 | |
668 | if (bit_adap->getsda == NULL || bit_adap->getscl == NULL) |
669 | dev_warn(&adap->dev, "Bus may be unreliable\n" ); |
670 | |
671 | return 0; |
672 | } |
673 | |
674 | int i2c_bit_add_bus(struct i2c_adapter *adap) |
675 | { |
676 | return __i2c_bit_add_bus(adap, add_adapter: i2c_add_adapter); |
677 | } |
678 | EXPORT_SYMBOL(i2c_bit_add_bus); |
679 | |
680 | int i2c_bit_add_numbered_bus(struct i2c_adapter *adap) |
681 | { |
682 | return __i2c_bit_add_bus(adap, add_adapter: i2c_add_numbered_adapter); |
683 | } |
684 | EXPORT_SYMBOL(i2c_bit_add_numbered_bus); |
685 | |
686 | MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>" ); |
687 | MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm" ); |
688 | MODULE_LICENSE("GPL" ); |
689 | |