1 /*
2 * i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
3 * Copyright (C) 2004 Arcom Control Systems
4 * Copyright (C) 2008 Pengutronix
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
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/delay.h>
21 #include <linux/jiffies.h>
22 #include <linux/errno.h>
23 #include <linux/i2c.h>
24 #include <linux/i2c-algo-pca.h>
25
26 #define DEB1(fmt, args...) do { if (i2c_debug >= 1) \
27 printk(KERN_DEBUG fmt, ## args); } while (0)
28 #define DEB2(fmt, args...) do { if (i2c_debug >= 2) \
29 printk(KERN_DEBUG fmt, ## args); } while (0)
30 #define DEB3(fmt, args...) do { if (i2c_debug >= 3) \
31 printk(KERN_DEBUG fmt, ## args); } while (0)
32
33 static int i2c_debug;
34
35 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
36 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
37
38 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
39 #define pca_clock(adap) adap->i2c_clock
40 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
41 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
42 #define pca_wait(adap) adap->wait_for_completion(adap->data)
43
pca_reset(struct i2c_algo_pca_data * adap)44 static void pca_reset(struct i2c_algo_pca_data *adap)
45 {
46 if (adap->chip == I2C_PCA_CHIP_9665) {
47 /* Ignore the reset function from the module,
48 * we can use the parallel bus reset.
49 */
50 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
51 pca_outw(adap, I2C_PCA_IND, 0xA5);
52 pca_outw(adap, I2C_PCA_IND, 0x5A);
53
54 /*
55 * After a reset we need to re-apply any configuration
56 * (calculated in pca_init) to get the bus in a working state.
57 */
58 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE);
59 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode);
60 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
61 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow);
62 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
63 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi);
64
65 pca_set_con(adap, I2C_PCA_CON_ENSIO);
66 } else {
67 adap->reset_chip(adap->data);
68 pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq);
69 }
70 }
71
72 /*
73 * Generate a start condition on the i2c bus.
74 *
75 * returns after the start condition has occurred
76 */
pca_start(struct i2c_algo_pca_data * adap)77 static int pca_start(struct i2c_algo_pca_data *adap)
78 {
79 int sta = pca_get_con(adap);
80 DEB2("=== START\n");
81 sta |= I2C_PCA_CON_STA;
82 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
83 pca_set_con(adap, sta);
84 return pca_wait(adap);
85 }
86
87 /*
88 * Generate a repeated start condition on the i2c bus
89 *
90 * return after the repeated start condition has occurred
91 */
pca_repeated_start(struct i2c_algo_pca_data * adap)92 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
93 {
94 int sta = pca_get_con(adap);
95 DEB2("=== REPEATED START\n");
96 sta |= I2C_PCA_CON_STA;
97 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
98 pca_set_con(adap, sta);
99 return pca_wait(adap);
100 }
101
102 /*
103 * Generate a stop condition on the i2c bus
104 *
105 * returns after the stop condition has been generated
106 *
107 * STOPs do not generate an interrupt or set the SI flag, since the
108 * part returns the idle state (0xf8). Hence we don't need to
109 * pca_wait here.
110 */
pca_stop(struct i2c_algo_pca_data * adap)111 static void pca_stop(struct i2c_algo_pca_data *adap)
112 {
113 int sta = pca_get_con(adap);
114 DEB2("=== STOP\n");
115 sta |= I2C_PCA_CON_STO;
116 sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
117 pca_set_con(adap, sta);
118 }
119
120 /*
121 * Send the slave address and R/W bit
122 *
123 * returns after the address has been sent
124 */
pca_address(struct i2c_algo_pca_data * adap,struct i2c_msg * msg)125 static int pca_address(struct i2c_algo_pca_data *adap,
126 struct i2c_msg *msg)
127 {
128 int sta = pca_get_con(adap);
129 int addr = i2c_8bit_addr_from_msg(msg);
130
131 DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
132 msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
133
134 pca_outw(adap, I2C_PCA_DAT, addr);
135
136 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
137 pca_set_con(adap, sta);
138
139 return pca_wait(adap);
140 }
141
142 /*
143 * Transmit a byte.
144 *
145 * Returns after the byte has been transmitted
146 */
pca_tx_byte(struct i2c_algo_pca_data * adap,__u8 b)147 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
148 __u8 b)
149 {
150 int sta = pca_get_con(adap);
151 DEB2("=== WRITE %#04x\n", b);
152 pca_outw(adap, I2C_PCA_DAT, b);
153
154 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
155 pca_set_con(adap, sta);
156
157 return pca_wait(adap);
158 }
159
160 /*
161 * Receive a byte
162 *
163 * returns immediately.
164 */
pca_rx_byte(struct i2c_algo_pca_data * adap,__u8 * b,int ack)165 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
166 __u8 *b, int ack)
167 {
168 *b = pca_inw(adap, I2C_PCA_DAT);
169 DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
170 }
171
172 /*
173 * Setup ACK or NACK for next received byte and wait for it to arrive.
174 *
175 * Returns after next byte has arrived.
176 */
pca_rx_ack(struct i2c_algo_pca_data * adap,int ack)177 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
178 int ack)
179 {
180 int sta = pca_get_con(adap);
181
182 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
183
184 if (ack)
185 sta |= I2C_PCA_CON_AA;
186
187 pca_set_con(adap, sta);
188 return pca_wait(adap);
189 }
190
pca_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)191 static int pca_xfer(struct i2c_adapter *i2c_adap,
192 struct i2c_msg *msgs,
193 int num)
194 {
195 struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
196 struct i2c_msg *msg = NULL;
197 int curmsg;
198 int numbytes = 0;
199 int state;
200 int ret;
201 int completed = 1;
202 unsigned long timeout = jiffies + i2c_adap->timeout;
203
204 while ((state = pca_status(adap)) != 0xf8) {
205 if (time_before(jiffies, timeout)) {
206 msleep(10);
207 } else {
208 dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
209 "%#04x\n", state);
210 return -EBUSY;
211 }
212 }
213
214 DEB1("{{{ XFER %d messages\n", num);
215
216 if (i2c_debug >= 2) {
217 for (curmsg = 0; curmsg < num; curmsg++) {
218 int addr, i;
219 msg = &msgs[curmsg];
220
221 addr = (0x7f & msg->addr) ;
222
223 if (msg->flags & I2C_M_RD)
224 printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
225 curmsg, msg->len, addr, (addr << 1) | 1);
226 else {
227 printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s",
228 curmsg, msg->len, addr, addr << 1,
229 msg->len == 0 ? "" : ", ");
230 for (i = 0; i < msg->len; i++)
231 printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
232 printk("]\n");
233 }
234 }
235 }
236
237 curmsg = 0;
238 ret = -EIO;
239 while (curmsg < num) {
240 state = pca_status(adap);
241
242 DEB3("STATE is 0x%02x\n", state);
243 msg = &msgs[curmsg];
244
245 switch (state) {
246 case 0xf8: /* On reset or stop the bus is idle */
247 completed = pca_start(adap);
248 break;
249
250 case 0x08: /* A START condition has been transmitted */
251 case 0x10: /* A repeated start condition has been transmitted */
252 completed = pca_address(adap, msg);
253 break;
254
255 case 0x18: /* SLA+W has been transmitted; ACK has been received */
256 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
257 if (numbytes < msg->len) {
258 completed = pca_tx_byte(adap,
259 msg->buf[numbytes]);
260 numbytes++;
261 break;
262 }
263 curmsg++; numbytes = 0;
264 if (curmsg == num)
265 pca_stop(adap);
266 else
267 completed = pca_repeated_start(adap);
268 break;
269
270 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
271 DEB2("NOT ACK received after SLA+W\n");
272 pca_stop(adap);
273 ret = -ENXIO;
274 goto out;
275
276 case 0x40: /* SLA+R has been transmitted; ACK has been received */
277 completed = pca_rx_ack(adap, msg->len > 1);
278 break;
279
280 case 0x50: /* Data bytes has been received; ACK has been returned */
281 if (numbytes < msg->len) {
282 pca_rx_byte(adap, &msg->buf[numbytes], 1);
283 numbytes++;
284 completed = pca_rx_ack(adap,
285 numbytes < msg->len - 1);
286 break;
287 }
288 curmsg++; numbytes = 0;
289 if (curmsg == num)
290 pca_stop(adap);
291 else
292 completed = pca_repeated_start(adap);
293 break;
294
295 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
296 DEB2("NOT ACK received after SLA+R\n");
297 pca_stop(adap);
298 ret = -ENXIO;
299 goto out;
300
301 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
302 DEB2("NOT ACK received after data byte\n");
303 pca_stop(adap);
304 goto out;
305
306 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
307 DEB2("Arbitration lost\n");
308 /*
309 * The PCA9564 data sheet (2006-09-01) says "A
310 * START condition will be transmitted when the
311 * bus becomes free (STOP or SCL and SDA high)"
312 * when the STA bit is set (p. 11).
313 *
314 * In case this won't work, try pca_reset()
315 * instead.
316 */
317 pca_start(adap);
318 goto out;
319
320 case 0x58: /* Data byte has been received; NOT ACK has been returned */
321 if (numbytes == msg->len - 1) {
322 pca_rx_byte(adap, &msg->buf[numbytes], 0);
323 curmsg++; numbytes = 0;
324 if (curmsg == num)
325 pca_stop(adap);
326 else
327 completed = pca_repeated_start(adap);
328 } else {
329 DEB2("NOT ACK sent after data byte received. "
330 "Not final byte. numbytes %d. len %d\n",
331 numbytes, msg->len);
332 pca_stop(adap);
333 goto out;
334 }
335 break;
336 case 0x70: /* Bus error - SDA stuck low */
337 DEB2("BUS ERROR - SDA Stuck low\n");
338 pca_reset(adap);
339 goto out;
340 case 0x78: /* Bus error - SCL stuck low (PCA9665) */
341 case 0x90: /* Bus error - SCL stuck low (PCA9564) */
342 DEB2("BUS ERROR - SCL Stuck low\n");
343 pca_reset(adap);
344 goto out;
345 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
346 DEB2("BUS ERROR - Illegal START or STOP\n");
347 pca_reset(adap);
348 goto out;
349 default:
350 dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
351 break;
352 }
353
354 if (!completed)
355 goto out;
356 }
357
358 ret = curmsg;
359 out:
360 DEB1("}}} transferred %d/%d messages. "
361 "status is %#04x. control is %#04x\n",
362 curmsg, num, pca_status(adap),
363 pca_get_con(adap));
364 return ret;
365 }
366
pca_func(struct i2c_adapter * adap)367 static u32 pca_func(struct i2c_adapter *adap)
368 {
369 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
370 }
371
372 static const struct i2c_algorithm pca_algo = {
373 .master_xfer = pca_xfer,
374 .functionality = pca_func,
375 };
376
pca_probe_chip(struct i2c_adapter * adap)377 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
378 {
379 struct i2c_algo_pca_data *pca_data = adap->algo_data;
380 /* The trick here is to check if there is an indirect register
381 * available. If there is one, we will read the value we first
382 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
383 * we wrote on I2C_PCA_ADR
384 */
385 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
386 pca_outw(pca_data, I2C_PCA_IND, 0xAA);
387 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
388 pca_outw(pca_data, I2C_PCA_IND, 0x00);
389 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
390 if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
391 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
392 pca_data->chip = I2C_PCA_CHIP_9665;
393 } else {
394 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
395 pca_data->chip = I2C_PCA_CHIP_9564;
396 }
397 return pca_data->chip;
398 }
399
pca_init(struct i2c_adapter * adap)400 static int pca_init(struct i2c_adapter *adap)
401 {
402 struct i2c_algo_pca_data *pca_data = adap->algo_data;
403
404 adap->algo = &pca_algo;
405
406 if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
407 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
408 int clock;
409
410 if (pca_data->i2c_clock > 7) {
411 switch (pca_data->i2c_clock) {
412 case 330000:
413 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
414 break;
415 case 288000:
416 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
417 break;
418 case 217000:
419 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
420 break;
421 case 146000:
422 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
423 break;
424 case 88000:
425 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
426 break;
427 case 59000:
428 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
429 break;
430 case 44000:
431 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
432 break;
433 case 36000:
434 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
435 break;
436 default:
437 printk(KERN_WARNING
438 "%s: Invalid I2C clock speed selected."
439 " Using default 59kHz.\n", adap->name);
440 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
441 }
442 } else {
443 printk(KERN_WARNING "%s: "
444 "Choosing the clock frequency based on "
445 "index is deprecated."
446 " Use the nominal frequency.\n", adap->name);
447 }
448
449 clock = pca_clock(pca_data);
450 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
451 adap->name, freqs[clock]);
452
453 /* Store settings as these will be needed when the PCA chip is reset */
454 pca_data->bus_settings.clock_freq = clock;
455
456 pca_reset(pca_data);
457 } else {
458 int clock;
459 int mode;
460 int tlow, thi;
461 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
462 int min_tlow, min_thi;
463 /* These values are the maximum raise and fall values allowed
464 * by the I2C operation mode (Standard, Fast or Fast+)
465 * They are used (added) below to calculate the clock dividers
466 * of PCA9665. Note that they are slightly different of the
467 * real maximum, to allow the change on mode exactly on the
468 * maximum clock rate for each mode
469 */
470 int raise_fall_time;
471
472 if (pca_data->i2c_clock > 1265800) {
473 printk(KERN_WARNING "%s: I2C clock speed too high."
474 " Using 1265.8kHz.\n", adap->name);
475 pca_data->i2c_clock = 1265800;
476 }
477
478 if (pca_data->i2c_clock < 60300) {
479 printk(KERN_WARNING "%s: I2C clock speed too low."
480 " Using 60.3kHz.\n", adap->name);
481 pca_data->i2c_clock = 60300;
482 }
483
484 /* To avoid integer overflow, use clock/100 for calculations */
485 clock = pca_clock(pca_data) / 100;
486
487 if (pca_data->i2c_clock > 1000000) {
488 mode = I2C_PCA_MODE_TURBO;
489 min_tlow = 14;
490 min_thi = 5;
491 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
492 } else if (pca_data->i2c_clock > 400000) {
493 mode = I2C_PCA_MODE_FASTP;
494 min_tlow = 17;
495 min_thi = 9;
496 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
497 } else if (pca_data->i2c_clock > 100000) {
498 mode = I2C_PCA_MODE_FAST;
499 min_tlow = 44;
500 min_thi = 20;
501 raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
502 } else {
503 mode = I2C_PCA_MODE_STD;
504 min_tlow = 157;
505 min_thi = 134;
506 raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
507 }
508
509 /* The minimum clock that respects the thi/tlow = 134/157 is
510 * 64800 Hz. Below that, we have to fix the tlow to 255 and
511 * calculate the thi factor.
512 */
513 if (clock < 648) {
514 tlow = 255;
515 thi = 1000000 - clock * raise_fall_time;
516 thi /= (I2C_PCA_OSC_PER * clock) - tlow;
517 } else {
518 tlow = (1000000 - clock * raise_fall_time) * min_tlow;
519 tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
520 thi = tlow * min_thi / min_tlow;
521 }
522
523 /* Store settings as these will be needed when the PCA chip is reset */
524 pca_data->bus_settings.mode = mode;
525 pca_data->bus_settings.tlow = tlow;
526 pca_data->bus_settings.thi = thi;
527
528 pca_reset(pca_data);
529
530 printk(KERN_INFO
531 "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
532 }
533 udelay(500); /* 500 us for oscillator to stabilise */
534
535 return 0;
536 }
537
538 /*
539 * registering functions to load algorithms at runtime
540 */
i2c_pca_add_bus(struct i2c_adapter * adap)541 int i2c_pca_add_bus(struct i2c_adapter *adap)
542 {
543 int rval;
544
545 rval = pca_init(adap);
546 if (rval)
547 return rval;
548
549 return i2c_add_adapter(adap);
550 }
551 EXPORT_SYMBOL(i2c_pca_add_bus);
552
i2c_pca_add_numbered_bus(struct i2c_adapter * adap)553 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
554 {
555 int rval;
556
557 rval = pca_init(adap);
558 if (rval)
559 return rval;
560
561 return i2c_add_numbered_adapter(adap);
562 }
563 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
564
565 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
566 "Wolfram Sang <w.sang@pengutronix.de>");
567 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
568 MODULE_LICENSE("GPL");
569
570 module_param(i2c_debug, int, 0);
571