Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux
[~shefty/rdma-dev.git] / drivers / i2c / algos / i2c-algo-bit.c
1 /* -------------------------------------------------------------------------
2  * i2c-algo-bit.c i2c driver algorithms for bit-shift adapters
3  * -------------------------------------------------------------------------
4  *   Copyright (C) 1995-2000 Simon G. Vogl
5
6     This program is free software; you can redistribute it and/or modify
7     it under the terms of the GNU General Public License as published by
8     the Free Software Foundation; either version 2 of the License, or
9     (at your option) any later version.
10
11     This program is distributed in the hope that it will be useful,
12     but WITHOUT ANY WARRANTY; without even the implied warranty of
13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14     GNU General Public License for more details.
15
16     You should have received a copy of the GNU General Public License
17     along with this program; if not, write to the Free Software
18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  * ------------------------------------------------------------------------- */
20
21 /* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
22    <kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */
23
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/delay.h>
27 #include <linux/init.h>
28 #include <linux/errno.h>
29 #include <linux/sched.h>
30 #include <linux/i2c.h>
31 #include <linux/i2c-algo-bit.h>
32
33
34 /* ----- global defines ----------------------------------------------- */
35
36 #ifdef DEBUG
37 #define bit_dbg(level, dev, format, args...) \
38         do { \
39                 if (i2c_debug >= level) \
40                         dev_dbg(dev, format, ##args); \
41         } while (0)
42 #else
43 #define bit_dbg(level, dev, format, args...) \
44         do {} while (0)
45 #endif /* DEBUG */
46
47 /* ----- global variables --------------------------------------------- */
48
49 static int bit_test;    /* see if the line-setting functions work       */
50 module_param(bit_test, int, S_IRUGO);
51 MODULE_PARM_DESC(bit_test, "lines testing - 0 off; 1 report; 2 fail if stuck");
52
53 #ifdef DEBUG
54 static int i2c_debug = 1;
55 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
56 MODULE_PARM_DESC(i2c_debug,
57                  "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
58 #endif
59
60 /* --- setting states on the bus with the right timing: --------------- */
61
62 #define setsda(adap, val)       adap->setsda(adap->data, val)
63 #define setscl(adap, val)       adap->setscl(adap->data, val)
64 #define getsda(adap)            adap->getsda(adap->data)
65 #define getscl(adap)            adap->getscl(adap->data)
66
67 static inline void sdalo(struct i2c_algo_bit_data *adap)
68 {
69         setsda(adap, 0);
70         udelay((adap->udelay + 1) / 2);
71 }
72
73 static inline void sdahi(struct i2c_algo_bit_data *adap)
74 {
75         setsda(adap, 1);
76         udelay((adap->udelay + 1) / 2);
77 }
78
79 static inline void scllo(struct i2c_algo_bit_data *adap)
80 {
81         setscl(adap, 0);
82         udelay(adap->udelay / 2);
83 }
84
85 /*
86  * Raise scl line, and do checking for delays. This is necessary for slower
87  * devices.
88  */
89 static int sclhi(struct i2c_algo_bit_data *adap)
90 {
91         unsigned long start;
92
93         setscl(adap, 1);
94
95         /* Not all adapters have scl sense line... */
96         if (!adap->getscl)
97                 goto done;
98
99         start = jiffies;
100         while (!getscl(adap)) {
101                 /* This hw knows how to read the clock line, so we wait
102                  * until it actually gets high.  This is safer as some
103                  * chips may hold it low ("clock stretching") while they
104                  * are processing data internally.
105                  */
106                 if (time_after(jiffies, start + adap->timeout)) {
107                         /* Test one last time, as we may have been preempted
108                          * between last check and timeout test.
109                          */
110                         if (getscl(adap))
111                                 break;
112                         return -ETIMEDOUT;
113                 }
114                 cond_resched();
115         }
116 #ifdef DEBUG
117         if (jiffies != start && i2c_debug >= 3)
118                 pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
119                          "high\n", jiffies - start);
120 #endif
121
122 done:
123         udelay(adap->udelay);
124         return 0;
125 }
126
127
128 /* --- other auxiliary functions -------------------------------------- */
129 static void i2c_start(struct i2c_algo_bit_data *adap)
130 {
131         /* assert: scl, sda are high */
132         setsda(adap, 0);
133         udelay(adap->udelay);
134         scllo(adap);
135 }
136
137 static void i2c_repstart(struct i2c_algo_bit_data *adap)
138 {
139         /* assert: scl is low */
140         sdahi(adap);
141         sclhi(adap);
142         setsda(adap, 0);
143         udelay(adap->udelay);
144         scllo(adap);
145 }
146
147
148 static void i2c_stop(struct i2c_algo_bit_data *adap)
149 {
150         /* assert: scl is low */
151         sdalo(adap);
152         sclhi(adap);
153         setsda(adap, 1);
154         udelay(adap->udelay);
155 }
156
157
158
159 /* send a byte without start cond., look for arbitration,
160    check ackn. from slave */
161 /* returns:
162  * 1 if the device acknowledged
163  * 0 if the device did not ack
164  * -ETIMEDOUT if an error occurred (while raising the scl line)
165  */
166 static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
167 {
168         int i;
169         int sb;
170         int ack;
171         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
172
173         /* assert: scl is low */
174         for (i = 7; i >= 0; i--) {
175                 sb = (c >> i) & 1;
176                 setsda(adap, sb);
177                 udelay((adap->udelay + 1) / 2);
178                 if (sclhi(adap) < 0) { /* timed out */
179                         bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
180                                 "timeout at bit #%d\n", (int)c, i);
181                         return -ETIMEDOUT;
182                 }
183                 /* FIXME do arbitration here:
184                  * if (sb && !getsda(adap)) -> ouch! Get out of here.
185                  *
186                  * Report a unique code, so higher level code can retry
187                  * the whole (combined) message and *NOT* issue STOP.
188                  */
189                 scllo(adap);
190         }
191         sdahi(adap);
192         if (sclhi(adap) < 0) { /* timeout */
193                 bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
194                         "timeout at ack\n", (int)c);
195                 return -ETIMEDOUT;
196         }
197
198         /* read ack: SDA should be pulled down by slave, or it may
199          * NAK (usually to report problems with the data we wrote).
200          */
201         ack = !getsda(adap);    /* ack: sda is pulled low -> success */
202         bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
203                 ack ? "A" : "NA");
204
205         scllo(adap);
206         return ack;
207         /* assert: scl is low (sda undef) */
208 }
209
210
211 static int i2c_inb(struct i2c_adapter *i2c_adap)
212 {
213         /* read byte via i2c port, without start/stop sequence  */
214         /* acknowledge is sent in i2c_read.                     */
215         int i;
216         unsigned char indata = 0;
217         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
218
219         /* assert: scl is low */
220         sdahi(adap);
221         for (i = 0; i < 8; i++) {
222                 if (sclhi(adap) < 0) { /* timeout */
223                         bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
224                                 "#%d\n", 7 - i);
225                         return -ETIMEDOUT;
226                 }
227                 indata *= 2;
228                 if (getsda(adap))
229                         indata |= 0x01;
230                 setscl(adap, 0);
231                 udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
232         }
233         /* assert: scl is low */
234         return indata;
235 }
236
237 /*
238  * Sanity check for the adapter hardware - check the reaction of
239  * the bus lines only if it seems to be idle.
240  */
241 static int test_bus(struct i2c_adapter *i2c_adap)
242 {
243         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
244         const char *name = i2c_adap->name;
245         int scl, sda, ret;
246
247         if (adap->pre_xfer) {
248                 ret = adap->pre_xfer(i2c_adap);
249                 if (ret < 0)
250                         return -ENODEV;
251         }
252
253         if (adap->getscl == NULL)
254                 pr_info("%s: Testing SDA only, SCL is not readable\n", name);
255
256         sda = getsda(adap);
257         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
258         if (!scl || !sda) {
259                 printk(KERN_WARNING
260                        "%s: bus seems to be busy (scl=%d, sda=%d)\n",
261                        name, scl, sda);
262                 goto bailout;
263         }
264
265         sdalo(adap);
266         sda = getsda(adap);
267         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
268         if (sda) {
269                 printk(KERN_WARNING "%s: SDA stuck high!\n", name);
270                 goto bailout;
271         }
272         if (!scl) {
273                 printk(KERN_WARNING "%s: SCL unexpected low "
274                        "while pulling SDA low!\n", name);
275                 goto bailout;
276         }
277
278         sdahi(adap);
279         sda = getsda(adap);
280         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
281         if (!sda) {
282                 printk(KERN_WARNING "%s: SDA stuck low!\n", name);
283                 goto bailout;
284         }
285         if (!scl) {
286                 printk(KERN_WARNING "%s: SCL unexpected low "
287                        "while pulling SDA high!\n", name);
288                 goto bailout;
289         }
290
291         scllo(adap);
292         sda = getsda(adap);
293         scl = (adap->getscl == NULL) ? 0 : getscl(adap);
294         if (scl) {
295                 printk(KERN_WARNING "%s: SCL stuck high!\n", name);
296                 goto bailout;
297         }
298         if (!sda) {
299                 printk(KERN_WARNING "%s: SDA unexpected low "
300                        "while pulling SCL low!\n", name);
301                 goto bailout;
302         }
303
304         sclhi(adap);
305         sda = getsda(adap);
306         scl = (adap->getscl == NULL) ? 1 : getscl(adap);
307         if (!scl) {
308                 printk(KERN_WARNING "%s: SCL stuck low!\n", name);
309                 goto bailout;
310         }
311         if (!sda) {
312                 printk(KERN_WARNING "%s: SDA unexpected low "
313                        "while pulling SCL high!\n", name);
314                 goto bailout;
315         }
316
317         if (adap->post_xfer)
318                 adap->post_xfer(i2c_adap);
319
320         pr_info("%s: Test OK\n", name);
321         return 0;
322 bailout:
323         sdahi(adap);
324         sclhi(adap);
325
326         if (adap->post_xfer)
327                 adap->post_xfer(i2c_adap);
328
329         return -ENODEV;
330 }
331
332 /* ----- Utility functions
333  */
334
335 /* try_address tries to contact a chip for a number of
336  * times before it gives up.
337  * return values:
338  * 1 chip answered
339  * 0 chip did not answer
340  * -x transmission error
341  */
342 static int try_address(struct i2c_adapter *i2c_adap,
343                        unsigned char addr, int retries)
344 {
345         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
346         int i, ret = 0;
347
348         for (i = 0; i <= retries; i++) {
349                 ret = i2c_outb(i2c_adap, addr);
350                 if (ret == 1 || i == retries)
351                         break;
352                 bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
353                 i2c_stop(adap);
354                 udelay(adap->udelay);
355                 yield();
356                 bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
357                 i2c_start(adap);
358         }
359         if (i && ret)
360                 bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
361                         "0x%02x: %s\n", i + 1,
362                         addr & 1 ? "read from" : "write to", addr >> 1,
363                         ret == 1 ? "success" : "failed, timeout?");
364         return ret;
365 }
366
367 static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
368 {
369         const unsigned char *temp = msg->buf;
370         int count = msg->len;
371         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
372         int retval;
373         int wrcount = 0;
374
375         while (count > 0) {
376                 retval = i2c_outb(i2c_adap, *temp);
377
378                 /* OK/ACK; or ignored NAK */
379                 if ((retval > 0) || (nak_ok && (retval == 0))) {
380                         count--;
381                         temp++;
382                         wrcount++;
383
384                 /* A slave NAKing the master means the slave didn't like
385                  * something about the data it saw.  For example, maybe
386                  * the SMBus PEC was wrong.
387                  */
388                 } else if (retval == 0) {
389                         dev_err(&i2c_adap->dev, "sendbytes: NAK bailout.\n");
390                         return -EIO;
391
392                 /* Timeout; or (someday) lost arbitration
393                  *
394                  * FIXME Lost ARB implies retrying the transaction from
395                  * the first message, after the "winning" master issues
396                  * its STOP.  As a rule, upper layer code has no reason
397                  * to know or care about this ... it is *NOT* an error.
398                  */
399                 } else {
400                         dev_err(&i2c_adap->dev, "sendbytes: error %d\n",
401                                         retval);
402                         return retval;
403                 }
404         }
405         return wrcount;
406 }
407
408 static int acknak(struct i2c_adapter *i2c_adap, int is_ack)
409 {
410         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
411
412         /* assert: sda is high */
413         if (is_ack)             /* send ack */
414                 setsda(adap, 0);
415         udelay((adap->udelay + 1) / 2);
416         if (sclhi(adap) < 0) {  /* timeout */
417                 dev_err(&i2c_adap->dev, "readbytes: ack/nak timeout\n");
418                 return -ETIMEDOUT;
419         }
420         scllo(adap);
421         return 0;
422 }
423
424 static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
425 {
426         int inval;
427         int rdcount = 0;        /* counts bytes read */
428         unsigned char *temp = msg->buf;
429         int count = msg->len;
430         const unsigned flags = msg->flags;
431
432         while (count > 0) {
433                 inval = i2c_inb(i2c_adap);
434                 if (inval >= 0) {
435                         *temp = inval;
436                         rdcount++;
437                 } else {   /* read timed out */
438                         break;
439                 }
440
441                 temp++;
442                 count--;
443
444                 /* Some SMBus transactions require that we receive the
445                    transaction length as the first read byte. */
446                 if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {
447                         if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
448                                 if (!(flags & I2C_M_NO_RD_ACK))
449                                         acknak(i2c_adap, 0);
450                                 dev_err(&i2c_adap->dev, "readbytes: invalid "
451                                         "block length (%d)\n", inval);
452                                 return -EPROTO;
453                         }
454                         /* The original count value accounts for the extra
455                            bytes, that is, either 1 for a regular transaction,
456                            or 2 for a PEC transaction. */
457                         count += inval;
458                         msg->len += inval;
459                 }
460
461                 bit_dbg(2, &i2c_adap->dev, "readbytes: 0x%02x %s\n",
462                         inval,
463                         (flags & I2C_M_NO_RD_ACK)
464                                 ? "(no ack/nak)"
465                                 : (count ? "A" : "NA"));
466
467                 if (!(flags & I2C_M_NO_RD_ACK)) {
468                         inval = acknak(i2c_adap, count);
469                         if (inval < 0)
470                                 return inval;
471                 }
472         }
473         return rdcount;
474 }
475
476 /* doAddress initiates the transfer by generating the start condition (in
477  * try_address) and transmits the address in the necessary format to handle
478  * reads, writes as well as 10bit-addresses.
479  * returns:
480  *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
481  * -x an error occurred (like: -ENXIO if the device did not answer, or
482  *      -ETIMEDOUT, for example if the lines are stuck...)
483  */
484 static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
485 {
486         unsigned short flags = msg->flags;
487         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
488         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
489
490         unsigned char addr;
491         int ret, retries;
492
493         retries = nak_ok ? 0 : i2c_adap->retries;
494
495         if (flags & I2C_M_TEN) {
496                 /* a ten bit address */
497                 addr = 0xf0 | ((msg->addr >> 7) & 0x06);
498                 bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
499                 /* try extended address code...*/
500                 ret = try_address(i2c_adap, addr, retries);
501                 if ((ret != 1) && !nak_ok)  {
502                         dev_err(&i2c_adap->dev,
503                                 "died at extended address code\n");
504                         return -ENXIO;
505                 }
506                 /* the remaining 8 bit address */
507                 ret = i2c_outb(i2c_adap, msg->addr & 0xff);
508                 if ((ret != 1) && !nak_ok) {
509                         /* the chip did not ack / xmission error occurred */
510                         dev_err(&i2c_adap->dev, "died at 2nd address code\n");
511                         return -ENXIO;
512                 }
513                 if (flags & I2C_M_RD) {
514                         bit_dbg(3, &i2c_adap->dev, "emitting repeated "
515                                 "start condition\n");
516                         i2c_repstart(adap);
517                         /* okay, now switch into reading mode */
518                         addr |= 0x01;
519                         ret = try_address(i2c_adap, addr, retries);
520                         if ((ret != 1) && !nak_ok) {
521                                 dev_err(&i2c_adap->dev,
522                                         "died at repeated address code\n");
523                                 return -EIO;
524                         }
525                 }
526         } else {                /* normal 7bit address  */
527                 addr = msg->addr << 1;
528                 if (flags & I2C_M_RD)
529                         addr |= 1;
530                 if (flags & I2C_M_REV_DIR_ADDR)
531                         addr ^= 1;
532                 ret = try_address(i2c_adap, addr, retries);
533                 if ((ret != 1) && !nak_ok)
534                         return -ENXIO;
535         }
536
537         return 0;
538 }
539
540 static int bit_xfer(struct i2c_adapter *i2c_adap,
541                     struct i2c_msg msgs[], int num)
542 {
543         struct i2c_msg *pmsg;
544         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
545         int i, ret;
546         unsigned short nak_ok;
547
548         if (adap->pre_xfer) {
549                 ret = adap->pre_xfer(i2c_adap);
550                 if (ret < 0)
551                         return ret;
552         }
553
554         bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
555         i2c_start(adap);
556         for (i = 0; i < num; i++) {
557                 pmsg = &msgs[i];
558                 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
559                 if (!(pmsg->flags & I2C_M_NOSTART)) {
560                         if (i) {
561                                 bit_dbg(3, &i2c_adap->dev, "emitting "
562                                         "repeated start condition\n");
563                                 i2c_repstart(adap);
564                         }
565                         ret = bit_doAddress(i2c_adap, pmsg);
566                         if ((ret != 0) && !nak_ok) {
567                                 bit_dbg(1, &i2c_adap->dev, "NAK from "
568                                         "device addr 0x%02x msg #%d\n",
569                                         msgs[i].addr, i);
570                                 goto bailout;
571                         }
572                 }
573                 if (pmsg->flags & I2C_M_RD) {
574                         /* read bytes into buffer*/
575                         ret = readbytes(i2c_adap, pmsg);
576                         if (ret >= 1)
577                                 bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
578                                         ret, ret == 1 ? "" : "s");
579                         if (ret < pmsg->len) {
580                                 if (ret >= 0)
581                                         ret = -EIO;
582                                 goto bailout;
583                         }
584                 } else {
585                         /* write bytes from buffer */
586                         ret = sendbytes(i2c_adap, pmsg);
587                         if (ret >= 1)
588                                 bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
589                                         ret, ret == 1 ? "" : "s");
590                         if (ret < pmsg->len) {
591                                 if (ret >= 0)
592                                         ret = -EIO;
593                                 goto bailout;
594                         }
595                 }
596         }
597         ret = i;
598
599 bailout:
600         bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
601         i2c_stop(adap);
602
603         if (adap->post_xfer)
604                 adap->post_xfer(i2c_adap);
605         return ret;
606 }
607
608 static u32 bit_func(struct i2c_adapter *adap)
609 {
610         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
611                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
612                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
613                I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
614 }
615
616
617 /* -----exported algorithm data: -------------------------------------  */
618
619 const struct i2c_algorithm i2c_bit_algo = {
620         .master_xfer    = bit_xfer,
621         .functionality  = bit_func,
622 };
623 EXPORT_SYMBOL(i2c_bit_algo);
624
625 /*
626  * registering functions to load algorithms at runtime
627  */
628 static int __i2c_bit_add_bus(struct i2c_adapter *adap,
629                              int (*add_adapter)(struct i2c_adapter *))
630 {
631         struct i2c_algo_bit_data *bit_adap = adap->algo_data;
632         int ret;
633
634         if (bit_test) {
635                 ret = test_bus(adap);
636                 if (bit_test >= 2 && ret < 0)
637                         return -ENODEV;
638         }
639
640         /* register new adapter to i2c module... */
641         adap->algo = &i2c_bit_algo;
642         adap->retries = 3;
643
644         ret = add_adapter(adap);
645         if (ret < 0)
646                 return ret;
647
648         /* Complain if SCL can't be read */
649         if (bit_adap->getscl == NULL) {
650                 dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
651                 dev_warn(&adap->dev, "Bus may be unreliable\n");
652         }
653         return 0;
654 }
655
656 int i2c_bit_add_bus(struct i2c_adapter *adap)
657 {
658         return __i2c_bit_add_bus(adap, i2c_add_adapter);
659 }
660 EXPORT_SYMBOL(i2c_bit_add_bus);
661
662 int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
663 {
664         return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
665 }
666 EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
667
668 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
669 MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
670 MODULE_LICENSE("GPL");