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24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/delay.h>
27#include <linux/slab.h>
28#include <linux/init.h>
29#include <linux/errno.h>
30#include <linux/sched.h>
31#include <linux/i2c.h>
32#include <linux/i2c-algo-bit.h>
33
34
35
36
37#ifdef DEBUG
38#define bit_dbg(level, dev, format, args...) \
39 do { \
40 if (i2c_debug >= level) \
41 dev_dbg(dev, format, ##args); \
42 } while (0)
43#else
44#define bit_dbg(level, dev, format, args...) \
45 do {} while (0)
46#endif
47
48
49
50static int bit_test;
51module_param(bit_test, bool, 0);
52MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
53
54#ifdef DEBUG
55static int i2c_debug = 1;
56module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
57MODULE_PARM_DESC(i2c_debug,
58 "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
59#endif
60
61
62
63#define setsda(adap, val) adap->setsda(adap->data, val)
64#define setscl(adap, val) adap->setscl(adap->data, val)
65#define getsda(adap) adap->getsda(adap->data)
66#define getscl(adap) adap->getscl(adap->data)
67
68static inline void sdalo(struct i2c_algo_bit_data *adap)
69{
70 setsda(adap, 0);
71 udelay((adap->udelay + 1) / 2);
72}
73
74static inline void sdahi(struct i2c_algo_bit_data *adap)
75{
76 setsda(adap, 1);
77 udelay((adap->udelay + 1) / 2);
78}
79
80static inline void scllo(struct i2c_algo_bit_data *adap)
81{
82 setscl(adap, 0);
83 udelay(adap->udelay / 2);
84}
85
86
87
88
89
90static int sclhi(struct i2c_algo_bit_data *adap)
91{
92 unsigned long start;
93
94 setscl(adap, 1);
95
96
97 if (!adap->getscl)
98 goto done;
99
100 start = jiffies;
101 while (!getscl(adap)) {
102
103
104
105
106
107 if (time_after(jiffies, start + adap->timeout))
108 return -ETIMEDOUT;
109 cond_resched();
110 }
111#ifdef DEBUG
112 if (jiffies != start && i2c_debug >= 3)
113 pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
114 "high\n", jiffies - start);
115#endif
116
117done:
118 udelay(adap->udelay);
119 return 0;
120}
121
122
123
124static void i2c_start(struct i2c_algo_bit_data *adap)
125{
126
127 setsda(adap, 0);
128 udelay(adap->udelay);
129 scllo(adap);
130}
131
132static void i2c_repstart(struct i2c_algo_bit_data *adap)
133{
134
135 sdahi(adap);
136 sclhi(adap);
137 setsda(adap, 0);
138 udelay(adap->udelay);
139 scllo(adap);
140}
141
142
143static void i2c_stop(struct i2c_algo_bit_data *adap)
144{
145
146 sdalo(adap);
147 sclhi(adap);
148 setsda(adap, 1);
149 udelay(adap->udelay);
150}
151
152
153
154
155
156
157
158
159
160
161static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
162{
163 int i;
164 int sb;
165 int ack;
166 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
167
168
169 for (i = 7; i >= 0; i--) {
170 sb = (c >> i) & 1;
171 setsda(adap, sb);
172 udelay((adap->udelay + 1) / 2);
173 if (sclhi(adap) < 0) {
174 bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
175 "timeout at bit #%d\n", (int)c, i);
176 return -ETIMEDOUT;
177 }
178
179
180
181
182
183
184 scllo(adap);
185 }
186 sdahi(adap);
187 if (sclhi(adap) < 0) {
188 bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
189 "timeout at ack\n", (int)c);
190 return -ETIMEDOUT;
191 }
192
193
194
195
196 ack = !getsda(adap);
197 bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
198 ack ? "A" : "NA");
199
200 scllo(adap);
201 return ack;
202
203}
204
205
206static int i2c_inb(struct i2c_adapter *i2c_adap)
207{
208
209
210 int i;
211 unsigned char indata = 0;
212 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
213
214
215 sdahi(adap);
216 for (i = 0; i < 8; i++) {
217 if (sclhi(adap) < 0) {
218 bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
219 "#%d\n", 7 - i);
220 return -ETIMEDOUT;
221 }
222 indata *= 2;
223 if (getsda(adap))
224 indata |= 0x01;
225 setscl(adap, 0);
226 udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
227 }
228
229 return indata;
230}
231
232
233
234
235
236static int test_bus(struct i2c_algo_bit_data *adap, char *name)
237{
238 int scl, sda;
239
240 if (adap->getscl == NULL)
241 pr_info("%s: Testing SDA only, SCL is not readable\n", name);
242
243 sda = getsda(adap);
244 scl = (adap->getscl == NULL) ? 1 : getscl(adap);
245 if (!scl || !sda) {
246 printk(KERN_WARNING "%s: bus seems to be busy\n", name);
247 goto bailout;
248 }
249
250 sdalo(adap);
251 sda = getsda(adap);
252 scl = (adap->getscl == NULL) ? 1 : getscl(adap);
253 if (sda) {
254 printk(KERN_WARNING "%s: SDA stuck high!\n", name);
255 goto bailout;
256 }
257 if (!scl) {
258 printk(KERN_WARNING "%s: SCL unexpected low "
259 "while pulling SDA low!\n", name);
260 goto bailout;
261 }
262
263 sdahi(adap);
264 sda = getsda(adap);
265 scl = (adap->getscl == NULL) ? 1 : getscl(adap);
266 if (!sda) {
267 printk(KERN_WARNING "%s: SDA stuck low!\n", name);
268 goto bailout;
269 }
270 if (!scl) {
271 printk(KERN_WARNING "%s: SCL unexpected low "
272 "while pulling SDA high!\n", name);
273 goto bailout;
274 }
275
276 scllo(adap);
277 sda = getsda(adap);
278 scl = (adap->getscl == NULL) ? 0 : getscl(adap);
279 if (scl) {
280 printk(KERN_WARNING "%s: SCL stuck high!\n", name);
281 goto bailout;
282 }
283 if (!sda) {
284 printk(KERN_WARNING "%s: SDA unexpected low "
285 "while pulling SCL low!\n", name);
286 goto bailout;
287 }
288
289 sclhi(adap);
290 sda = getsda(adap);
291 scl = (adap->getscl == NULL) ? 1 : getscl(adap);
292 if (!scl) {
293 printk(KERN_WARNING "%s: SCL stuck low!\n", name);
294 goto bailout;
295 }
296 if (!sda) {
297 printk(KERN_WARNING "%s: SDA unexpected low "
298 "while pulling SCL high!\n", name);
299 goto bailout;
300 }
301 pr_info("%s: Test OK\n", name);
302 return 0;
303bailout:
304 sdahi(adap);
305 sclhi(adap);
306 return -ENODEV;
307}
308
309
310
311
312
313
314
315
316
317
318
319static 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, 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, "Used %d tries to %s client at "
338 "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
344static 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, *temp);
354
355
356 if ((retval > 0) || (nak_ok && (retval == 0))) {
357 count--;
358 temp++;
359 wrcount++;
360
361
362
363
364
365 } else if (retval == 0) {
366 dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
367 return -EIO;
368
369
370
371
372
373
374
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
385static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
386{
387 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
388
389
390 if (is_ack)
391 setsda(adap, 0);
392 udelay((adap->udelay + 1) / 2);
393 if (sclhi(adap) < 0) {
394 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
395 return -ETIMEDOUT;
396 }
397 scllo(adap);
398 return 0;
399}
400
401static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
402{
403 int inval;
404 int rdcount = 0;
405 unsigned char *temp = msg->buf;
406 int count = msg->len;
407 const unsigned flags = msg->flags;
408
409 while (count > 0) {
410 inval = i2c_inb(i2c_adap);
411 if (inval >= 0) {
412 *temp = inval;
413 rdcount++;
414 } else {
415 break;
416 }
417
418 temp++;
419 count--;
420
421
422
423 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
424 if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
425 if (!(flags & I2C_M_NO_RD_ACK))
426 acknak(i2c_adap, 0);
427 dev_err(&i2c_adap->dev, "readbytes: invalid "
428 "block length (%d)\n", inval);
429 return -EREMOTEIO;
430 }
431
432
433
434 count += inval;
435 msg->len += inval;
436 }
437
438 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
439 inval,
440 (flags & I2C_M_NO_RD_ACK)
441 ? "(no ack/nak)"
442 : (count ? "A" : "NA"));
443
444 if (!(flags & I2C_M_NO_RD_ACK)) {
445 inval = acknak(i2c_adap, count);
446 if (inval < 0)
447 return inval;
448 }
449 }
450 return rdcount;
451}
452
453
454
455
456
457
458
459
460
461static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
462{
463 unsigned short flags = msg->flags;
464 unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
465 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
466
467 unsigned char addr;
468 int ret, retries;
469
470 retries = nak_ok ? 0 : i2c_adap->retries;
471
472 if (flags & I2C_M_TEN) {
473
474 addr = 0xf0 | ((msg->addr >> 7) & 0x03);
475 bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
476
477 ret = try_address(i2c_adap, addr, retries);
478 if ((ret != 1) && !nak_ok) {
479 dev_err(&i2c_adap->dev,
480 "died at extended address code\n");
481 return -EREMOTEIO;
482 }
483
484 ret = i2c_outb(i2c_adap, msg->addr & 0x7f);
485 if ((ret != 1) && !nak_ok) {
486
487 dev_err(&i2c_adap->dev, "died at 2nd address code\n");
488 return -EREMOTEIO;
489 }
490 if (flags & I2C_M_RD) {
491 bit_dbg(3, &i2c_adap->dev, "emitting repeated "
492 "start condition\n");
493 i2c_repstart(adap);
494
495 addr |= 0x01;
496 ret = try_address(i2c_adap, addr, retries);
497 if ((ret != 1) && !nak_ok) {
498 dev_err(&i2c_adap->dev,
499 "died at repeated address code\n");
500 return -EREMOTEIO;
501 }
502 }
503 } else {
504 addr = msg->addr << 1;
505 if (flags & I2C_M_RD)
506 addr |= 1;
507 if (flags & I2C_M_REV_DIR_ADDR)
508 addr ^= 1;
509 ret = try_address(i2c_adap, addr, retries);
510 if ((ret != 1) && !nak_ok)
511 return -ENXIO;
512 }
513
514 return 0;
515}
516
517static int bit_xfer(struct i2c_adapter *i2c_adap,
518 struct i2c_msg msgs[], int num)
519{
520 struct i2c_msg *pmsg;
521 struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
522 int i, ret;
523 unsigned short nak_ok;
524
525 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
526 i2c_start(adap);
527 for (i = 0; i < num; i++) {
528 pmsg = &msgs[i];
529 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
530 if (!(pmsg->flags & I2C_M_NOSTART)) {
531 if (i) {
532 bit_dbg(3, &i2c_adap->dev, "emitting "
533 "repeated start condition\n");
534 i2c_repstart(adap);
535 }
536 ret = bit_doAddress(i2c_adap, pmsg);
537 if ((ret != 0) && !nak_ok) {
538 bit_dbg(1, &i2c_adap->dev, "NAK from "
539 "device addr 0x%02x msg #%d\n",
540 msgs[i].addr, i);
541 goto bailout;
542 }
543 }
544 if (pmsg->flags & I2C_M_RD) {
545
546 ret = readbytes(i2c_adap, pmsg);
547 if (ret >= 1)
548 bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
549 ret, ret == 1 ? "" : "s");
550 if (ret < pmsg->len) {
551 if (ret >= 0)
552 ret = -EREMOTEIO;
553 goto bailout;
554 }
555 } else {
556
557 ret = sendbytes(i2c_adap, pmsg);
558 if (ret >= 1)
559 bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
560 ret, ret == 1 ? "" : "s");
561 if (ret < pmsg->len) {
562 if (ret >= 0)
563 ret = -EREMOTEIO;
564 goto bailout;
565 }
566 }
567 }
568 ret = i;
569
570bailout:
571 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
572 i2c_stop(adap);
573 return ret;
574}
575
576static u32 bit_func(struct i2c_adapter *adap)
577{
578 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
579 I2C_FUNC_SMBUS_READ_BLOCK_DATA |
580 I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
581 I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
582}
583
584
585
586
587static const struct i2c_algorithm i2c_bit_algo = {
588 .master_xfer = bit_xfer,
589 .functionality = bit_func,
590};
591
592
593
594
595static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
596{
597 struct i2c_algo_bit_data *bit_adap = adap->algo_data;
598
599 if (bit_test) {
600 int ret = test_bus(bit_adap, adap->name);
601 if (ret < 0)
602 return -ENODEV;
603 }
604
605
606 adap->algo = &i2c_bit_algo;
607 adap->retries = 3;
608
609 return 0;
610}
611
612int i2c_bit_add_bus(struct i2c_adapter *adap)
613{
614 int err;
615
616 err = i2c_bit_prepare_bus(adap);
617 if (err)
618 return err;
619
620 return i2c_add_adapter(adap);
621}
622EXPORT_SYMBOL(i2c_bit_add_bus);
623
624int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
625{
626 int err;
627
628 err = i2c_bit_prepare_bus(adap);
629 if (err)
630 return err;
631
632 return i2c_add_numbered_adapter(adap);
633}
634EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
635
636MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
637MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
638MODULE_LICENSE("GPL");
639