xref: /openbmc/linux/drivers/i2c/algos/i2c-algo-pcf.c (revision 9ac8d3fb)
1 /* ------------------------------------------------------------------------- */
2 /* i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters		     */
3 /* ------------------------------------------------------------------------- */
4 /*   Copyright (C) 1995-1997 Simon G. Vogl
5                    1998-2000 Hans Berglund
6 
7     This program is free software; you can redistribute it and/or modify
8     it under the terms of the GNU General Public License as published by
9     the Free Software Foundation; either version 2 of the License, or
10     (at your option) any later version.
11 
12     This program is distributed in the hope that it will be useful,
13     but WITHOUT ANY WARRANTY; without even the implied warranty of
14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15     GNU General Public License for more details.
16 
17     You should have received a copy of the GNU General Public License
18     along with this program; if not, write to the Free Software
19     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.		     */
20 /* ------------------------------------------------------------------------- */
21 
22 /* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
23    Frodo Looijaard <frodol@dds.nl> ,and also from Martin Bailey
24    <mbailey@littlefeet-inc.com> */
25 
26 /* Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
27    messages, proper stop/repstart signaling during receive,
28    added detect code */
29 
30 #include <linux/kernel.h>
31 #include <linux/module.h>
32 #include <linux/delay.h>
33 #include <linux/slab.h>
34 #include <linux/init.h>
35 #include <linux/errno.h>
36 #include <linux/i2c.h>
37 #include <linux/i2c-algo-pcf.h>
38 #include "i2c-algo-pcf.h"
39 
40 
41 #define DEB2(x) if (i2c_debug>=2) x
42 #define DEB3(x) if (i2c_debug>=3) x /* print several statistical values*/
43 #define DEBPROTO(x) if (i2c_debug>=9) x;
44  	/* debug the protocol by showing transferred bits */
45 #define DEF_TIMEOUT 16
46 
47 /* module parameters:
48  */
49 static int i2c_debug;
50 
51 /* --- setting states on the bus with the right timing: ---------------	*/
52 
53 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
54 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
55 #define get_own(adap) adap->getown(adap->data)
56 #define get_clock(adap) adap->getclock(adap->data)
57 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
58 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
59 
60 /* --- other auxiliary functions --------------------------------------	*/
61 
62 static void i2c_start(struct i2c_algo_pcf_data *adap)
63 {
64 	DEBPROTO(printk("S "));
65 	set_pcf(adap, 1, I2C_PCF_START);
66 }
67 
68 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
69 {
70 	DEBPROTO(printk(" Sr "));
71 	set_pcf(adap, 1, I2C_PCF_REPSTART);
72 }
73 
74 
75 static void i2c_stop(struct i2c_algo_pcf_data *adap)
76 {
77 	DEBPROTO(printk("P\n"));
78 	set_pcf(adap, 1, I2C_PCF_STOP);
79 }
80 
81 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
82 {
83 	DEB2(printk(KERN_INFO
84 		"i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
85 		 *status));
86 
87 	/* Cleanup from LAB -- reset and enable ESO.
88 	 * This resets the PCF8584; since we've lost the bus, no
89 	 * further attempts should be made by callers to clean up
90 	 * (no i2c_stop() etc.)
91 	 */
92 	set_pcf(adap, 1, I2C_PCF_PIN);
93 	set_pcf(adap, 1, I2C_PCF_ESO);
94 
95 	/* We pause for a time period sufficient for any running
96 	 * I2C transaction to complete -- the arbitration logic won't
97 	 * work properly until the next START is seen.
98 	 * It is assumed the bus driver or client has set a proper value.
99 	 *
100 	 * REVISIT: should probably use msleep instead of mdelay if we
101 	 * know we can sleep.
102 	 */
103 	if (adap->lab_mdelay)
104 		mdelay(adap->lab_mdelay);
105 
106 	DEB2(printk(KERN_INFO
107 		"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
108 		get_pcf(adap, 1)));
109 }
110 
111 static int wait_for_bb(struct i2c_algo_pcf_data *adap) {
112 
113 	int timeout = DEF_TIMEOUT;
114 	int status;
115 
116 	status = get_pcf(adap, 1);
117 #ifndef STUB_I2C
118 	while (timeout-- && !(status & I2C_PCF_BB)) {
119 		udelay(100); /* wait for 100 us */
120 		status = get_pcf(adap, 1);
121 	}
122 #endif
123 	if (timeout <= 0) {
124 		printk(KERN_ERR "Timeout waiting for Bus Busy\n");
125 	}
126 
127 	return (timeout<=0);
128 }
129 
130 
131 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) {
132 
133 	int timeout = DEF_TIMEOUT;
134 
135 	*status = get_pcf(adap, 1);
136 #ifndef STUB_I2C
137 	while (timeout-- && (*status & I2C_PCF_PIN)) {
138 		adap->waitforpin(adap->data);
139 		*status = get_pcf(adap, 1);
140 	}
141 	if (*status & I2C_PCF_LAB) {
142 		handle_lab(adap, status);
143 		return(-EINTR);
144 	}
145 #endif
146 	if (timeout <= 0)
147 		return(-1);
148 	else
149 		return(0);
150 }
151 
152 /*
153  * This should perform the 'PCF8584 initialization sequence' as described
154  * in the Philips IC12 data book (1995, Aug 29).
155  * There should be a 30 clock cycle wait after reset, I assume this
156  * has been fulfilled.
157  * There should be a delay at the end equal to the longest I2C message
158  * to synchronize the BB-bit (in multimaster systems). How long is
159  * this? I assume 1 second is always long enough.
160  *
161  * vdovikin: added detect code for PCF8584
162  */
163 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
164 {
165 	unsigned char temp;
166 
167 	DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n", get_pcf(adap, 1)));
168 
169 	/* S1=0x80: S0 selected, serial interface off */
170 	set_pcf(adap, 1, I2C_PCF_PIN);
171 	/* check to see S1 now used as R/W ctrl -
172 	   PCF8584 does that when ESO is zero */
173 	if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
174 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
175 		return -ENXIO; /* definetly not PCF8584 */
176 	}
177 
178 	/* load own address in S0, effective address is (own << 1)	*/
179 	i2c_outb(adap, get_own(adap));
180 	/* check it's really written */
181 	if ((temp = i2c_inb(adap)) != get_own(adap)) {
182 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
183 		return -ENXIO;
184 	}
185 
186 	/* S1=0xA0, next byte in S2					*/
187 	set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
188 	/* check to see S2 now selected */
189 	if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
190 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
191 		return -ENXIO;
192 	}
193 
194 	/* load clock register S2					*/
195 	i2c_outb(adap, get_clock(adap));
196 	/* check it's really written, the only 5 lowest bits does matter */
197 	if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
198 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
199 		return -ENXIO;
200 	}
201 
202 	/* Enable serial interface, idle, S0 selected			*/
203 	set_pcf(adap, 1, I2C_PCF_IDLE);
204 
205 	/* check to see PCF is really idled and we can access status register */
206 	if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
207 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
208 		return -ENXIO;
209 	}
210 
211 	printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
212 
213 	return 0;
214 }
215 
216 
217 /* ----- Utility functions
218  */
219 
220 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
221                          int count, int last)
222 {
223 	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
224 	int wrcount, status, timeout;
225 
226 	for (wrcount=0; wrcount<count; ++wrcount) {
227 		DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
228 				buf[wrcount]&0xff));
229 		i2c_outb(adap, buf[wrcount]);
230 		timeout = wait_for_pin(adap, &status);
231 		if (timeout) {
232 			if (timeout == -EINTR) {
233 				/* arbitration lost */
234 				return -EINTR;
235 			}
236 			i2c_stop(adap);
237 			dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
238 			return -EREMOTEIO; /* got a better one ?? */
239 		}
240 #ifndef STUB_I2C
241 		if (status & I2C_PCF_LRB) {
242 			i2c_stop(adap);
243 			dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
244 			return -EREMOTEIO; /* got a better one ?? */
245 		}
246 #endif
247 	}
248 	if (last) {
249 		i2c_stop(adap);
250 	}
251 	else {
252 		i2c_repstart(adap);
253 	}
254 
255 	return (wrcount);
256 }
257 
258 
259 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
260                          int count, int last)
261 {
262 	int i, status;
263 	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
264 	int wfp;
265 
266 	/* increment number of bytes to read by one -- read dummy byte */
267 	for (i = 0; i <= count; i++) {
268 
269 		if ((wfp = wait_for_pin(adap, &status))) {
270 			if (wfp == -EINTR) {
271 				/* arbitration lost */
272 				return -EINTR;
273 			}
274 			i2c_stop(adap);
275 			dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
276 			return (-1);
277 		}
278 
279 #ifndef STUB_I2C
280 		if ((status & I2C_PCF_LRB) && (i != count)) {
281 			i2c_stop(adap);
282 			dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
283 			return (-1);
284 		}
285 #endif
286 
287 		if (i == count - 1) {
288 			set_pcf(adap, 1, I2C_PCF_ESO);
289 		} else
290 		if (i == count) {
291 			if (last) {
292 				i2c_stop(adap);
293 			} else {
294 				i2c_repstart(adap);
295 			}
296 		};
297 
298 		if (i) {
299 			buf[i - 1] = i2c_inb(adap);
300 		} else {
301 			i2c_inb(adap); /* dummy read */
302 		}
303 	}
304 
305 	return (i - 1);
306 }
307 
308 
309 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
310 			 struct i2c_msg *msg)
311 {
312 	unsigned short flags = msg->flags;
313 	unsigned char addr;
314 
315 	addr = msg->addr << 1;
316 	if (flags & I2C_M_RD)
317 		addr |= 1;
318 	if (flags & I2C_M_REV_DIR_ADDR)
319 		addr ^= 1;
320 	i2c_outb(adap, addr);
321 
322 	return 0;
323 }
324 
325 static int pcf_xfer(struct i2c_adapter *i2c_adap,
326 		    struct i2c_msg *msgs,
327 		    int num)
328 {
329 	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
330 	struct i2c_msg *pmsg;
331 	int i;
332 	int ret=0, timeout, status;
333 
334 	if (adap->xfer_begin)
335 		adap->xfer_begin(adap->data);
336 
337 	/* Check for bus busy */
338 	timeout = wait_for_bb(adap);
339 	if (timeout) {
340 		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
341 		            "Timeout waiting for BB in pcf_xfer\n");)
342 		i = -EIO;
343 		goto out;
344 	}
345 
346 	for (i = 0;ret >= 0 && i < num; i++) {
347 		pmsg = &msgs[i];
348 
349 		DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
350 		     pmsg->flags & I2C_M_RD ? "read" : "write",
351                      pmsg->len, pmsg->addr, i + 1, num);)
352 
353 		ret = pcf_doAddress(adap, pmsg);
354 
355 		/* Send START */
356 		if (i == 0) {
357 			i2c_start(adap);
358 		}
359 
360 		/* Wait for PIN (pending interrupt NOT) */
361 		timeout = wait_for_pin(adap, &status);
362 		if (timeout) {
363 			if (timeout == -EINTR) {
364 				/* arbitration lost */
365 				i = -EINTR;
366 				goto out;
367 			}
368 			i2c_stop(adap);
369 			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
370 				    "for PIN(1) in pcf_xfer\n");)
371 			i = -EREMOTEIO;
372 			goto out;
373 		}
374 
375 #ifndef STUB_I2C
376 		/* Check LRB (last rcvd bit - slave ack) */
377 		if (status & I2C_PCF_LRB) {
378 			i2c_stop(adap);
379 			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
380 			i = -EREMOTEIO;
381 			goto out;
382 		}
383 #endif
384 
385 		DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
386 			    i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
387 
388 		/* Read */
389 		if (pmsg->flags & I2C_M_RD) {
390 			/* read bytes into buffer*/
391 			ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
392                                             (i + 1 == num));
393 
394 			if (ret != pmsg->len) {
395 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
396 					    "only read %d bytes.\n",ret));
397 			} else {
398 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
399 			}
400 		} else { /* Write */
401 			ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
402                                             (i + 1 == num));
403 
404 			if (ret != pmsg->len) {
405 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
406 					    "only wrote %d bytes.\n",ret));
407 			} else {
408 				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
409 			}
410 		}
411 	}
412 
413 out:
414 	if (adap->xfer_end)
415 		adap->xfer_end(adap->data);
416 	return (i);
417 }
418 
419 static u32 pcf_func(struct i2c_adapter *adap)
420 {
421 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
422 	       I2C_FUNC_PROTOCOL_MANGLING;
423 }
424 
425 /* -----exported algorithm data: -------------------------------------	*/
426 
427 static const struct i2c_algorithm pcf_algo = {
428 	.master_xfer	= pcf_xfer,
429 	.functionality	= pcf_func,
430 };
431 
432 /*
433  * registering functions to load algorithms at runtime
434  */
435 int i2c_pcf_add_bus(struct i2c_adapter *adap)
436 {
437 	struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
438 	int rval;
439 
440 	DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
441 
442 	/* register new adapter to i2c module... */
443 	adap->algo = &pcf_algo;
444 	adap->timeout = 100;
445 
446 	if ((rval = pcf_init_8584(pcf_adap)))
447 		return rval;
448 
449 	rval = i2c_add_adapter(adap);
450 
451 	return rval;
452 }
453 EXPORT_SYMBOL(i2c_pcf_add_bus);
454 
455 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
456 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
457 MODULE_LICENSE("GPL");
458 
459 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
460 MODULE_PARM_DESC(i2c_debug,
461         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
462