MAINTAINER change for Connect Tech Inc
[linux-2.6.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/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 /* ----- global defines ----------------------------------------------- */
36 #define DEB(x) if (i2c_debug>=1) x;
37 #define DEB2(x) if (i2c_debug>=2) x;
38 #define DEBSTAT(x) if (i2c_debug>=3) x; /* print several statistical values*/
39 #define DEBPROTO(x) if (i2c_debug>=9) { x; }
40         /* debug the protocol by showing transferred bits */
41
42
43 /* ----- global variables --------------------------------------------- */
44
45 /* module parameters:
46  */
47 static int i2c_debug;
48 static int bit_test;    /* see if the line-setting functions work       */
49
50 /* --- setting states on the bus with the right timing: --------------- */
51
52 #define setsda(adap,val) adap->setsda(adap->data, val)
53 #define setscl(adap,val) adap->setscl(adap->data, val)
54 #define getsda(adap) adap->getsda(adap->data)
55 #define getscl(adap) adap->getscl(adap->data)
56
57 static inline void sdalo(struct i2c_algo_bit_data *adap)
58 {
59         setsda(adap,0);
60         udelay(adap->udelay);
61 }
62
63 static inline void sdahi(struct i2c_algo_bit_data *adap)
64 {
65         setsda(adap,1);
66         udelay(adap->udelay);
67 }
68
69 static inline void scllo(struct i2c_algo_bit_data *adap)
70 {
71         setscl(adap,0);
72         udelay(adap->udelay);
73 }
74
75 /*
76  * Raise scl line, and do checking for delays. This is necessary for slower
77  * devices.
78  */
79 static int sclhi(struct i2c_algo_bit_data *adap)
80 {
81         unsigned long start;
82
83         setscl(adap,1);
84
85         /* Not all adapters have scl sense line... */
86         if (!adap->getscl)
87                 goto done;
88
89         start=jiffies;
90         while (! getscl(adap) ) {       
91                 /* the hw knows how to read the clock line,
92                  * so we wait until it actually gets high.
93                  * This is safer as some chips may hold it low
94                  * while they are processing data internally. 
95                  */
96                 if (time_after_eq(jiffies, start+adap->timeout)) {
97                         return -ETIMEDOUT;
98                 }
99                 cond_resched();
100         }
101         DEBSTAT(printk(KERN_DEBUG "needed %ld jiffies\n", jiffies-start));
102
103 done:
104         udelay(adap->udelay);
105         return 0;
106
107
108
109 /* --- other auxiliary functions -------------------------------------- */
110 static void i2c_start(struct i2c_algo_bit_data *adap) 
111 {
112         /* assert: scl, sda are high */
113         DEBPROTO(printk("S "));
114         sdalo(adap);
115         scllo(adap);
116 }
117
118 static void i2c_repstart(struct i2c_algo_bit_data *adap) 
119 {
120         /* scl, sda may not be high */
121         DEBPROTO(printk(" Sr "));
122         setsda(adap,1);
123         sclhi(adap);
124         
125         sdalo(adap);
126         scllo(adap);
127 }
128
129
130 static void i2c_stop(struct i2c_algo_bit_data *adap) 
131 {
132         DEBPROTO(printk("P\n"));
133         /* assert: scl is low */
134         sdalo(adap);
135         sclhi(adap); 
136         sdahi(adap);
137 }
138
139
140
141 /* send a byte without start cond., look for arbitration, 
142    check ackn. from slave */
143 /* returns:
144  * 1 if the device acknowledged
145  * 0 if the device did not ack
146  * -ETIMEDOUT if an error occurred (while raising the scl line)
147  */
148 static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
149 {
150         int i;
151         int sb;
152         int ack;
153         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
154
155         /* assert: scl is low */
156         for ( i=7 ; i>=0 ; i-- ) {
157                 sb = c & ( 1 << i );
158                 setsda(adap,sb);
159                 udelay(adap->udelay);
160                 DEBPROTO(printk(KERN_DEBUG "%d",sb!=0));
161                 if (sclhi(adap)<0) { /* timed out */
162                         sdahi(adap); /* we don't want to block the net */
163                         DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at bit #%d\n", c&0xff, i));
164                         return -ETIMEDOUT;
165                 };
166                 /* do arbitration here: 
167                  * if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
168                  */
169                 setscl(adap, 0 );
170                 udelay(adap->udelay);
171         }
172         sdahi(adap);
173         if (sclhi(adap)<0){ /* timeout */
174             DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at ack\n", c&0xff));
175             return -ETIMEDOUT;
176         };
177         /* read ack: SDA should be pulled down by slave */
178         ack=getsda(adap);       /* ack: sda is pulled low ->success.     */
179         DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x , getsda() = %d\n", c & 0xff, ack));
180
181         DEBPROTO( printk(KERN_DEBUG "[%2.2x]",c&0xff) );
182         DEBPROTO(if (0==ack){ printk(KERN_DEBUG " A ");} else printk(KERN_DEBUG " NA ") );
183         scllo(adap);
184         return 0==ack;          /* return 1 if device acked      */
185         /* assert: scl is low (sda undef) */
186 }
187
188
189 static int i2c_inb(struct i2c_adapter *i2c_adap) 
190 {
191         /* read byte via i2c port, without start/stop sequence  */
192         /* acknowledge is sent in i2c_read.                     */
193         int i;
194         unsigned char indata=0;
195         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
196
197         /* assert: scl is low */
198         sdahi(adap);
199         for (i=0;i<8;i++) {
200                 if (sclhi(adap)<0) { /* timeout */
201                         DEB2(printk(KERN_DEBUG " i2c_inb: timeout at bit #%d\n", 7-i));
202                         return -ETIMEDOUT;
203                 };
204                 indata *= 2;
205                 if ( getsda(adap) ) 
206                         indata |= 0x01;
207                 scllo(adap);
208         }
209         /* assert: scl is low */
210         DEB2(printk(KERN_DEBUG "i2c_inb: 0x%02x\n", indata & 0xff));
211
212         DEBPROTO(printk(KERN_DEBUG " 0x%02x", indata & 0xff));
213         return (int) (indata & 0xff);
214 }
215
216 /*
217  * Sanity check for the adapter hardware - check the reaction of
218  * the bus lines only if it seems to be idle.
219  */
220 static int test_bus(struct i2c_algo_bit_data *adap, char* name) {
221         int scl,sda;
222
223         if (adap->getscl==NULL)
224                 printk(KERN_INFO "i2c-algo-bit.o: Testing SDA only, "
225                         "SCL is not readable.\n");
226
227         sda=getsda(adap);
228         scl=(adap->getscl==NULL?1:getscl(adap));
229         printk(KERN_DEBUG "i2c-algo-bit.o: (0) scl=%d, sda=%d\n",scl,sda);
230         if (!scl || !sda ) {
231                 printk(KERN_WARNING "i2c-algo-bit.o: %s seems to be busy.\n", name);
232                 goto bailout;
233         }
234
235         sdalo(adap);
236         sda=getsda(adap);
237         scl=(adap->getscl==NULL?1:getscl(adap));
238         printk(KERN_DEBUG "i2c-algo-bit.o: (1) scl=%d, sda=%d\n",scl,sda);
239         if ( 0 != sda ) {
240                 printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck high!\n");
241                 goto bailout;
242         }
243         if ( 0 == scl ) {
244                 printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low "
245                         "while pulling SDA low!\n");
246                 goto bailout;
247         }               
248
249         sdahi(adap);
250         sda=getsda(adap);
251         scl=(adap->getscl==NULL?1:getscl(adap));
252         printk(KERN_DEBUG "i2c-algo-bit.o: (2) scl=%d, sda=%d\n",scl,sda);
253         if ( 0 == sda ) {
254                 printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck low!\n");
255                 goto bailout;
256         }
257         if ( 0 == scl ) {
258                 printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low "
259                         "while pulling SDA high!\n");
260                 goto bailout;
261         }
262
263         scllo(adap);
264         sda=getsda(adap);
265         scl=(adap->getscl==NULL?0:getscl(adap));
266         printk(KERN_DEBUG "i2c-algo-bit.o: (3) scl=%d, sda=%d\n",scl,sda);
267         if ( 0 != scl ) {
268                 printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck high!\n");
269                 goto bailout;
270         }
271         if ( 0 == sda ) {
272                 printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low "
273                         "while pulling SCL low!\n");
274                 goto bailout;
275         }
276         
277         sclhi(adap);
278         sda=getsda(adap);
279         scl=(adap->getscl==NULL?1:getscl(adap));
280         printk(KERN_DEBUG "i2c-algo-bit.o: (4) scl=%d, sda=%d\n",scl,sda);
281         if ( 0 == scl ) {
282                 printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck low!\n");
283                 goto bailout;
284         }
285         if ( 0 == sda ) {
286                 printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low "
287                         "while pulling SCL high!\n");
288                 goto bailout;
289         }
290         printk(KERN_INFO "i2c-algo-bit.o: %s passed test.\n",name);
291         return 0;
292 bailout:
293         sdahi(adap);
294         sclhi(adap);
295         return -ENODEV;
296 }
297
298 /* ----- Utility functions
299  */
300
301 /* try_address tries to contact a chip for a number of
302  * times before it gives up.
303  * return values:
304  * 1 chip answered
305  * 0 chip did not answer
306  * -x transmission error
307  */
308 static int try_address(struct i2c_adapter *i2c_adap,
309                        unsigned char addr, int retries)
310 {
311         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
312         int i,ret = -1;
313         for (i=0;i<=retries;i++) {
314                 ret = i2c_outb(i2c_adap,addr);
315                 if (ret==1)
316                         break;  /* success! */
317                 i2c_stop(adap);
318                 udelay(5/*adap->udelay*/);
319                 if (i==retries)  /* no success */
320                         break;
321                 i2c_start(adap);
322                 udelay(adap->udelay);
323         }
324         DEB2(if (i)
325              printk(KERN_DEBUG "i2c-algo-bit.o: Used %d tries to %s client at 0x%02x : %s\n",
326                     i+1, addr & 1 ? "read" : "write", addr>>1,
327                     ret==1 ? "success" : ret==0 ? "no ack" : "failed, timeout?" )
328             );
329         return ret;
330 }
331
332 static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
333 {
334         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
335         char c;
336         const char *temp = msg->buf;
337         int count = msg->len;
338         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK; 
339         int retval;
340         int wrcount=0;
341
342         while (count > 0) {
343                 c = *temp;
344                 DEB2(dev_dbg(&i2c_adap->dev, "sendbytes: writing %2.2X\n", c&0xff));
345                 retval = i2c_outb(i2c_adap,c);
346                 if ((retval>0) || (nak_ok && (retval==0)))  { /* ok or ignored NAK */
347                         count--; 
348                         temp++;
349                         wrcount++;
350                 } else { /* arbitration or no acknowledge */
351                         dev_err(&i2c_adap->dev, "sendbytes: error - bailout.\n");
352                         i2c_stop(adap);
353                         return (retval<0)? retval : -EFAULT;
354                                 /* got a better one ?? */
355                 }
356         }
357         return wrcount;
358 }
359
360 static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
361 {
362         int inval;
363         int rdcount=0;          /* counts bytes read */
364         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
365         char *temp = msg->buf;
366         int count = msg->len;
367
368         while (count > 0) {
369                 inval = i2c_inb(i2c_adap);
370                 if (inval>=0) {
371                         *temp = inval;
372                         rdcount++;
373                 } else {   /* read timed out */
374                         printk(KERN_ERR "i2c-algo-bit.o: readbytes: i2c_inb timed out.\n");
375                         break;
376                 }
377
378                 temp++;
379                 count--;
380
381                 if (msg->flags & I2C_M_NO_RD_ACK)
382                         continue;
383
384                 if ( count > 0 ) {              /* send ack */
385                         sdalo(adap);
386                         DEBPROTO(printk(" Am "));
387                 } else {
388                         sdahi(adap);    /* neg. ack on last byte */
389                         DEBPROTO(printk(" NAm "));
390                 }
391                 if (sclhi(adap)<0) {    /* timeout */
392                         sdahi(adap);
393                         printk(KERN_ERR "i2c-algo-bit.o: readbytes: Timeout at ack\n");
394                         return -ETIMEDOUT;
395                 };
396                 scllo(adap);
397                 sdahi(adap);
398         }
399         return rdcount;
400 }
401
402 /* doAddress initiates the transfer by generating the start condition (in
403  * try_address) and transmits the address in the necessary format to handle
404  * reads, writes as well as 10bit-addresses.
405  * returns:
406  *  0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
407  * -x an error occurred (like: -EREMOTEIO if the device did not answer, or
408  *      -ETIMEDOUT, for example if the lines are stuck...) 
409  */
410 static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
411 {
412         unsigned short flags = msg->flags;
413         unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
414         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
415
416         unsigned char addr;
417         int ret, retries;
418
419         retries = nak_ok ? 0 : i2c_adap->retries;
420         
421         if ( (flags & I2C_M_TEN)  ) { 
422                 /* a ten bit address */
423                 addr = 0xf0 | (( msg->addr >> 7) & 0x03);
424                 DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
425                 /* try extended address code...*/
426                 ret = try_address(i2c_adap, addr, retries);
427                 if ((ret != 1) && !nak_ok)  {
428                         printk(KERN_ERR "died at extended address code.\n");
429                         return -EREMOTEIO;
430                 }
431                 /* the remaining 8 bit address */
432                 ret = i2c_outb(i2c_adap,msg->addr & 0x7f);
433                 if ((ret != 1) && !nak_ok) {
434                         /* the chip did not ack / xmission error occurred */
435                         printk(KERN_ERR "died at 2nd address code.\n");
436                         return -EREMOTEIO;
437                 }
438                 if ( flags & I2C_M_RD ) {
439                         i2c_repstart(adap);
440                         /* okay, now switch into reading mode */
441                         addr |= 0x01;
442                         ret = try_address(i2c_adap, addr, retries);
443                         if ((ret!=1) && !nak_ok) {
444                                 printk(KERN_ERR "died at extended address code.\n");
445                                 return -EREMOTEIO;
446                         }
447                 }
448         } else {                /* normal 7bit address  */
449                 addr = ( msg->addr << 1 );
450                 if (flags & I2C_M_RD )
451                         addr |= 1;
452                 if (flags & I2C_M_REV_DIR_ADDR )
453                         addr ^= 1;
454                 ret = try_address(i2c_adap, addr, retries);
455                 if ((ret!=1) && !nak_ok)
456                         return -EREMOTEIO;
457         }
458
459         return 0;
460 }
461
462 static int bit_xfer(struct i2c_adapter *i2c_adap,
463                     struct i2c_msg msgs[], int num)
464 {
465         struct i2c_msg *pmsg;
466         struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
467         
468         int i,ret;
469         unsigned short nak_ok;
470
471         i2c_start(adap);
472         for (i=0;i<num;i++) {
473                 pmsg = &msgs[i];
474                 nak_ok = pmsg->flags & I2C_M_IGNORE_NAK; 
475                 if (!(pmsg->flags & I2C_M_NOSTART)) {
476                         if (i) {
477                                 i2c_repstart(adap);
478                         }
479                         ret = bit_doAddress(i2c_adap, pmsg);
480                         if ((ret != 0) && !nak_ok) {
481                             DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: NAK from device addr %2.2x msg #%d\n"
482                                         ,msgs[i].addr,i));
483                             return (ret<0) ? ret : -EREMOTEIO;
484                         }
485                 }
486                 if (pmsg->flags & I2C_M_RD ) {
487                         /* read bytes into buffer*/
488                         ret = readbytes(i2c_adap, pmsg);
489                         DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: read %d bytes.\n",ret));
490                         if (ret < pmsg->len ) {
491                                 return (ret<0)? ret : -EREMOTEIO;
492                         }
493                 } else {
494                         /* write bytes from buffer */
495                         ret = sendbytes(i2c_adap, pmsg);
496                         DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: wrote %d bytes.\n",ret));
497                         if (ret < pmsg->len ) {
498                                 return (ret<0) ? ret : -EREMOTEIO;
499                         }
500                 }
501         }
502         i2c_stop(adap);
503         return num;
504 }
505
506 static u32 bit_func(struct i2c_adapter *adap)
507 {
508         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 
509                I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
510 }
511
512
513 /* -----exported algorithm data: -------------------------------------  */
514
515 static const struct i2c_algorithm i2c_bit_algo = {
516         .master_xfer    = bit_xfer,
517         .functionality  = bit_func,
518 };
519
520 /* 
521  * registering functions to load algorithms at runtime 
522  */
523 int i2c_bit_add_bus(struct i2c_adapter *adap)
524 {
525         struct i2c_algo_bit_data *bit_adap = adap->algo_data;
526
527         if (bit_test) {
528                 int ret = test_bus(bit_adap, adap->name);
529                 if (ret<0)
530                         return -ENODEV;
531         }
532
533         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
534
535         /* register new adapter to i2c module... */
536         adap->algo = &i2c_bit_algo;
537
538         adap->timeout = 100;    /* default values, should       */
539         adap->retries = 3;      /* be replaced by defines       */
540
541         return i2c_add_adapter(adap);
542 }
543 EXPORT_SYMBOL(i2c_bit_add_bus);
544
545 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
546 MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
547 MODULE_LICENSE("GPL");
548
549 module_param(bit_test, bool, 0);
550 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
551
552 MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
553 MODULE_PARM_DESC(i2c_debug,
554                  "debug level - 0 off; 1 normal; 2,3 more verbose; 9 bit-protocol");