aboutsummaryrefslogtreecommitdiff
path: root/drivers/i2c/algos/i2c-algo-pcf.c
blob: 5b24930adb5a7b9e23721f47aca79daa7b450d04 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
/* ------------------------------------------------------------------------- */
/* i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters		     */
/* ------------------------------------------------------------------------- */
/*   Copyright (C) 1995-1997 Simon G. Vogl
                   1998-2000 Hans Berglund

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.		     */
/* ------------------------------------------------------------------------- */

/* With some changes from Ky�sti M�lkki <kmalkki@cc.hut.fi> and 
   Frodo Looijaard <frodol@dds.nl> ,and also from Martin Bailey
   <mbailey@littlefeet-inc.com> */

/* Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
   messages, proper stop/repstart signaling during receive,
   added detect code */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-pcf.h>
#include "i2c-algo-pcf.h"


#define DEB2(x) if (i2c_debug>=2) x
#define DEB3(x) if (i2c_debug>=3) x /* print several statistical values*/
#define DEBPROTO(x) if (i2c_debug>=9) x;
 	/* debug the protocol by showing transferred bits */
#define DEF_TIMEOUT 16

/* module parameters:
 */
static int i2c_debug;

/* --- setting states on the bus with the right timing: ---------------	*/

#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
#define get_own(adap) adap->getown(adap->data)
#define get_clock(adap) adap->getclock(adap->data)
#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
#define i2c_inb(adap) adap->getpcf(adap->data, 0)

/* --- other auxiliary functions --------------------------------------	*/

static void i2c_start(struct i2c_algo_pcf_data *adap) 
{
	DEBPROTO(printk("S "));
	set_pcf(adap, 1, I2C_PCF_START);
}

static void i2c_repstart(struct i2c_algo_pcf_data *adap) 
{
	DEBPROTO(printk(" Sr "));
	set_pcf(adap, 1, I2C_PCF_REPSTART);
}


static void i2c_stop(struct i2c_algo_pcf_data *adap) 
{
	DEBPROTO(printk("P\n"));
	set_pcf(adap, 1, I2C_PCF_STOP);
}

static int wait_for_bb(struct i2c_algo_pcf_data *adap) {

	int timeout = DEF_TIMEOUT;
	int status;

	status = get_pcf(adap, 1);
#ifndef STUB_I2C
	while (timeout-- && !(status & I2C_PCF_BB)) {
		udelay(100); /* wait for 100 us */
		status = get_pcf(adap, 1);
	}
#endif
	if (timeout <= 0) {
		printk(KERN_ERR "Timeout waiting for Bus Busy\n");
	}
	
	return (timeout<=0);
}


static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) {

	int timeout = DEF_TIMEOUT;

	*status = get_pcf(adap, 1);
#ifndef STUB_I2C
	while (timeout-- && (*status & I2C_PCF_PIN)) {
		adap->waitforpin();
		*status = get_pcf(adap, 1);
	}
	if (*status & I2C_PCF_LAB) {
		DEB2(printk(KERN_INFO 
			"i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
			 *status));
		/* Cleanup from LAB-- reset and enable ESO.
		 * This resets the PCF8584; since we've lost the bus, no
		 * further attempts should be made by callers to clean up 
		 * (no i2c_stop() etc.)
		 */
		set_pcf(adap, 1, I2C_PCF_PIN);
		set_pcf(adap, 1, I2C_PCF_ESO);
		/* TODO: we should pause for a time period sufficient for any
		 * running I2C transaction to complete-- the arbitration
		 * logic won't work properly until the next START is seen.
		 */
		DEB2(printk(KERN_INFO 
			"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n", 
			get_pcf(adap,1)));
		return(-EINTR);
	}
#endif
	if (timeout <= 0)
		return(-1);
	else
		return(0);
}

/* 
 * This should perform the 'PCF8584 initialization sequence' as described
 * in the Philips IC12 data book (1995, Aug 29).
 * There should be a 30 clock cycle wait after reset, I assume this
 * has been fulfilled.
 * There should be a delay at the end equal to the longest I2C message
 * to synchronize the BB-bit (in multimaster systems). How long is
 * this? I assume 1 second is always long enough.
 *
 * vdovikin: added detect code for PCF8584
 */
static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
{
	unsigned char temp;

	DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n", get_pcf(adap, 1)));

	/* S1=0x80: S0 selected, serial interface off */
	set_pcf(adap, 1, I2C_PCF_PIN);
	/* check to see S1 now used as R/W ctrl -
	   PCF8584 does that when ESO is zero */
	if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
		return -ENXIO; /* definetly not PCF8584 */
	}

	/* load own address in S0, effective address is (own << 1)	*/
	i2c_outb(adap, get_own(adap));
	/* check it's really written */
	if ((temp = i2c_inb(adap)) != get_own(adap)) {
		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
		return -ENXIO;
	}

	/* S1=0xA0, next byte in S2					*/
	set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
	/* check to see S2 now selected */
	if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
		return -ENXIO;
	}

	/* load clock register S2					*/
	i2c_outb(adap, get_clock(adap));
	/* check it's really written, the only 5 lowest bits does matter */
	if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
		return -ENXIO;
	}

	/* Enable serial interface, idle, S0 selected			*/
	set_pcf(adap, 1, I2C_PCF_IDLE);

	/* check to see PCF is really idled and we can access status register */
	if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
		return -ENXIO;
	}
	
	printk(KERN_DEBUG "i2c-algo-pcf.o: deteted and initialized PCF8584.\n");

	return 0;
}


/* ----- Utility functions
 */

static inline int try_address(struct i2c_algo_pcf_data *adap,
		       unsigned char addr, int retries)
{
	int i, status, ret = -1;
	int wfp;
	for (i=0;i<retries;i++) {
		i2c_outb(adap, addr);
		i2c_start(adap);
		status = get_pcf(adap, 1);
		if ((wfp = wait_for_pin(adap, &status)) >= 0) {
			if ((status & I2C_PCF_LRB) == 0) { 
				i2c_stop(adap);
				break;	/* success! */
			}
		}
		if (wfp == -EINTR) {
			/* arbitration lost */
			udelay(adap->udelay);
			return -EINTR;
		}
		i2c_stop(adap);
		udelay(adap->udelay);
	}
	DEB2(if (i) printk(KERN_DEBUG "i2c-algo-pcf.o: needed %d retries for %d\n",i,
	                   addr));
	return ret;
}


static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
                         int count, int last)
{
	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
	int wrcount, status, timeout;
    
	for (wrcount=0; wrcount<count; ++wrcount) {
		DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
				buf[wrcount]&0xff));
		i2c_outb(adap, buf[wrcount]);
		timeout = wait_for_pin(adap, &status);
		if (timeout) {
			if (timeout == -EINTR) {
				/* arbitration lost */
				return -EINTR;
			}
			i2c_stop(adap);
			dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
			return -EREMOTEIO; /* got a better one ?? */
		}
#ifndef STUB_I2C
		if (status & I2C_PCF_LRB) {
			i2c_stop(adap);
			dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
			return -EREMOTEIO; /* got a better one ?? */
		}
#endif
	}
	if (last) {
		i2c_stop(adap);
	}
	else {
		i2c_repstart(adap);
	}

	return (wrcount);
}


static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
                         int count, int last)
{
	int i, status;
	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
	int wfp;

	/* increment number of bytes to read by one -- read dummy byte */
	for (i = 0; i <= count; i++) {

		if ((wfp = wait_for_pin(adap, &status))) {
			if (wfp == -EINTR) {
				/* arbitration lost */
				return -EINTR;
			}
			i2c_stop(adap);
			dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
			return (-1);
		}

#ifndef STUB_I2C
		if ((status & I2C_PCF_LRB) && (i != count)) {
			i2c_stop(adap);
			dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
			return (-1);
		}
#endif
		
		if (i == count - 1) {
			set_pcf(adap, 1, I2C_PCF_ESO);
		} else 
		if (i == count) {
			if (last) {
				i2c_stop(adap);
			} else {
				i2c_repstart(adap);
			}
		};

		if (i) {
			buf[i - 1] = i2c_inb(adap);
		} else {
			i2c_inb(adap); /* dummy read */
		}
	}

	return (i - 1);
}


static inline int pcf_doAddress(struct i2c_algo_pcf_data *adap,
                                struct i2c_msg *msg, int retries) 
{
	unsigned short flags = msg->flags;
	unsigned char addr;
	int ret;
	if ( (flags & I2C_M_TEN)  ) { 
		/* a ten bit address */
		addr = 0xf0 | (( msg->addr >> 7) & 0x03);
		DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
		/* try extended address code...*/
		ret = try_address(adap, addr, retries);
		if (ret!=1) {
			printk(KERN_ERR "died at extended address code.\n");
			return -EREMOTEIO;
		}
		/* the remaining 8 bit address */
		i2c_outb(adap,msg->addr & 0x7f);
/* Status check comes here */
		if (ret != 1) {
			printk(KERN_ERR "died at 2nd address code.\n");
			return -EREMOTEIO;
		}
		if ( flags & I2C_M_RD ) {
			i2c_repstart(adap);
			/* okay, now switch into reading mode */
			addr |= 0x01;
			ret = try_address(adap, addr, retries);
			if (ret!=1) {
				printk(KERN_ERR "died at extended address code.\n");
				return -EREMOTEIO;
			}
		}
	} else {		/* normal 7bit address	*/
		addr = ( msg->addr << 1 );
		if (flags & I2C_M_RD )
			addr |= 1;
		if (flags & I2C_M_REV_DIR_ADDR )
			addr ^= 1;
		i2c_outb(adap, addr);
	}
	return 0;
}

static int pcf_xfer(struct i2c_adapter *i2c_adap,
		    struct i2c_msg *msgs, 
		    int num)
{
	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
	struct i2c_msg *pmsg;
	int i;
	int ret=0, timeout, status;
    

	/* Check for bus busy */
	timeout = wait_for_bb(adap);
	if (timeout) {
		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
		            "Timeout waiting for BB in pcf_xfer\n");)
		return -EIO;
	}
	
	for (i = 0;ret >= 0 && i < num; i++) {
		pmsg = &msgs[i];

		DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
		     pmsg->flags & I2C_M_RD ? "read" : "write",
                     pmsg->len, pmsg->addr, i + 1, num);)
    
		ret = pcf_doAddress(adap, pmsg, i2c_adap->retries);

		/* Send START */
		if (i == 0) {
			i2c_start(adap); 
		}
    
		/* Wait for PIN (pending interrupt NOT) */
		timeout = wait_for_pin(adap, &status);
		if (timeout) {
			if (timeout == -EINTR) {
				/* arbitration lost */
				return (-EINTR);
			}
			i2c_stop(adap);
			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
				    "for PIN(1) in pcf_xfer\n");)
			return (-EREMOTEIO);
		}
    
#ifndef STUB_I2C
		/* Check LRB (last rcvd bit - slave ack) */
		if (status & I2C_PCF_LRB) {
			i2c_stop(adap);
			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
			return (-EREMOTEIO);
		}
#endif
    
		DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
			    i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
    
		/* Read */
		if (pmsg->flags & I2C_M_RD) {
			/* read bytes into buffer*/
			ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
                                            (i + 1 == num));
        
			if (ret != pmsg->len) {
				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
					    "only read %d bytes.\n",ret));
			} else {
				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
			}
		} else { /* Write */
			ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
                                            (i + 1 == num));
        
			if (ret != pmsg->len) {
				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
					    "only wrote %d bytes.\n",ret));
			} else {
				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
			}
		}
	}

	return (i);
}

static u32 pcf_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 
	       I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING; 
}

/* -----exported algorithm data: -------------------------------------	*/

static struct i2c_algorithm pcf_algo = {
	.master_xfer	= pcf_xfer,
	.functionality	= pcf_func,
};

/* 
 * registering functions to load algorithms at runtime 
 */
int i2c_pcf_add_bus(struct i2c_adapter *adap)
{
	struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
	int rval;

	DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));

	/* register new adapter to i2c module... */
	adap->algo = &pcf_algo;

	adap->timeout = 100;		/* default values, should	*/
	adap->retries = 3;		/* be replaced by defines	*/

	if ((rval = pcf_init_8584(pcf_adap)))
		return rval;

	rval = i2c_add_adapter(adap);

	return rval;
}


int i2c_pcf_del_bus(struct i2c_adapter *adap)
{
	return i2c_del_adapter(adap);
}

EXPORT_SYMBOL(i2c_pcf_add_bus);
EXPORT_SYMBOL(i2c_pcf_del_bus);

MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
MODULE_LICENSE("GPL");

module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(i2c_debug,
        "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");