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 } else {
54 adap->reset_chip(adap->data);
55 }
56 }
57
58 /*
59 * Generate a start condition on the i2c bus.
60 *
61 * returns after the start condition has occurred
62 */
pca_start(struct i2c_algo_pca_data * adap)63 static int pca_start(struct i2c_algo_pca_data *adap)
64 {
65 int sta = pca_get_con(adap);
66 DEB2("=== START\n");
67 sta |= I2C_PCA_CON_STA;
68 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
69 pca_set_con(adap, sta);
70 return pca_wait(adap);
71 }
72
73 /*
74 * Generate a repeated start condition on the i2c bus
75 *
76 * return after the repeated start condition has occurred
77 */
pca_repeated_start(struct i2c_algo_pca_data * adap)78 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
79 {
80 int sta = pca_get_con(adap);
81 DEB2("=== REPEATED START\n");
82 sta |= I2C_PCA_CON_STA;
83 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
84 pca_set_con(adap, sta);
85 return pca_wait(adap);
86 }
87
88 /*
89 * Generate a stop condition on the i2c bus
90 *
91 * returns after the stop condition has been generated
92 *
93 * STOPs do not generate an interrupt or set the SI flag, since the
94 * part returns the idle state (0xf8). Hence we don't need to
95 * pca_wait here.
96 */
pca_stop(struct i2c_algo_pca_data * adap)97 static void pca_stop(struct i2c_algo_pca_data *adap)
98 {
99 int sta = pca_get_con(adap);
100 DEB2("=== STOP\n");
101 sta |= I2C_PCA_CON_STO;
102 sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
103 pca_set_con(adap, sta);
104 }
105
106 /*
107 * Send the slave address and R/W bit
108 *
109 * returns after the address has been sent
110 */
pca_address(struct i2c_algo_pca_data * adap,struct i2c_msg * msg)111 static int pca_address(struct i2c_algo_pca_data *adap,
112 struct i2c_msg *msg)
113 {
114 int sta = pca_get_con(adap);
115 int addr = i2c_8bit_addr_from_msg(msg);
116
117 DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
118 msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
119
120 pca_outw(adap, I2C_PCA_DAT, addr);
121
122 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
123 pca_set_con(adap, sta);
124
125 return pca_wait(adap);
126 }
127
128 /*
129 * Transmit a byte.
130 *
131 * Returns after the byte has been transmitted
132 */
pca_tx_byte(struct i2c_algo_pca_data * adap,__u8 b)133 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
134 __u8 b)
135 {
136 int sta = pca_get_con(adap);
137 DEB2("=== WRITE %#04x\n", b);
138 pca_outw(adap, I2C_PCA_DAT, b);
139
140 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
141 pca_set_con(adap, sta);
142
143 return pca_wait(adap);
144 }
145
146 /*
147 * Receive a byte
148 *
149 * returns immediately.
150 */
pca_rx_byte(struct i2c_algo_pca_data * adap,__u8 * b,int ack)151 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
152 __u8 *b, int ack)
153 {
154 *b = pca_inw(adap, I2C_PCA_DAT);
155 DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
156 }
157
158 /*
159 * Setup ACK or NACK for next received byte and wait for it to arrive.
160 *
161 * Returns after next byte has arrived.
162 */
pca_rx_ack(struct i2c_algo_pca_data * adap,int ack)163 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
164 int ack)
165 {
166 int sta = pca_get_con(adap);
167
168 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
169
170 if (ack)
171 sta |= I2C_PCA_CON_AA;
172
173 pca_set_con(adap, sta);
174 return pca_wait(adap);
175 }
176
pca_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)177 static int pca_xfer(struct i2c_adapter *i2c_adap,
178 struct i2c_msg *msgs,
179 int num)
180 {
181 struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
182 struct i2c_msg *msg = NULL;
183 int curmsg;
184 int numbytes = 0;
185 int state;
186 int ret;
187 int completed = 1;
188 unsigned long timeout = jiffies + i2c_adap->timeout;
189
190 while ((state = pca_status(adap)) != 0xf8) {
191 if (time_before(jiffies, timeout)) {
192 msleep(10);
193 } else {
194 dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
195 "%#04x\n", state);
196 return -EBUSY;
197 }
198 }
199
200 DEB1("{{{ XFER %d messages\n", num);
201
202 if (i2c_debug >= 2) {
203 for (curmsg = 0; curmsg < num; curmsg++) {
204 int addr, i;
205 msg = &msgs[curmsg];
206
207 addr = (0x7f & msg->addr) ;
208
209 if (msg->flags & I2C_M_RD)
210 printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
211 curmsg, msg->len, addr, (addr << 1) | 1);
212 else {
213 printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s",
214 curmsg, msg->len, addr, addr << 1,
215 msg->len == 0 ? "" : ", ");
216 for (i = 0; i < msg->len; i++)
217 printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
218 printk("]\n");
219 }
220 }
221 }
222
223 curmsg = 0;
224 ret = -EIO;
225 while (curmsg < num) {
226 state = pca_status(adap);
227
228 DEB3("STATE is 0x%02x\n", state);
229 msg = &msgs[curmsg];
230
231 switch (state) {
232 case 0xf8: /* On reset or stop the bus is idle */
233 completed = pca_start(adap);
234 break;
235
236 case 0x08: /* A START condition has been transmitted */
237 case 0x10: /* A repeated start condition has been transmitted */
238 completed = pca_address(adap, msg);
239 break;
240
241 case 0x18: /* SLA+W has been transmitted; ACK has been received */
242 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
243 if (numbytes < msg->len) {
244 completed = pca_tx_byte(adap,
245 msg->buf[numbytes]);
246 numbytes++;
247 break;
248 }
249 curmsg++; numbytes = 0;
250 if (curmsg == num)
251 pca_stop(adap);
252 else
253 completed = pca_repeated_start(adap);
254 break;
255
256 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
257 DEB2("NOT ACK received after SLA+W\n");
258 pca_stop(adap);
259 ret = -ENXIO;
260 goto out;
261
262 case 0x40: /* SLA+R has been transmitted; ACK has been received */
263 completed = pca_rx_ack(adap, msg->len > 1);
264 break;
265
266 case 0x50: /* Data bytes has been received; ACK has been returned */
267 if (numbytes < msg->len) {
268 pca_rx_byte(adap, &msg->buf[numbytes], 1);
269 numbytes++;
270 completed = pca_rx_ack(adap,
271 numbytes < msg->len - 1);
272 break;
273 }
274 curmsg++; numbytes = 0;
275 if (curmsg == num)
276 pca_stop(adap);
277 else
278 completed = pca_repeated_start(adap);
279 break;
280
281 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
282 DEB2("NOT ACK received after SLA+R\n");
283 pca_stop(adap);
284 ret = -ENXIO;
285 goto out;
286
287 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
288 DEB2("NOT ACK received after data byte\n");
289 pca_stop(adap);
290 goto out;
291
292 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
293 DEB2("Arbitration lost\n");
294 /*
295 * The PCA9564 data sheet (2006-09-01) says "A
296 * START condition will be transmitted when the
297 * bus becomes free (STOP or SCL and SDA high)"
298 * when the STA bit is set (p. 11).
299 *
300 * In case this won't work, try pca_reset()
301 * instead.
302 */
303 pca_start(adap);
304 goto out;
305
306 case 0x58: /* Data byte has been received; NOT ACK has been returned */
307 if (numbytes == msg->len - 1) {
308 pca_rx_byte(adap, &msg->buf[numbytes], 0);
309 curmsg++; numbytes = 0;
310 if (curmsg == num)
311 pca_stop(adap);
312 else
313 completed = pca_repeated_start(adap);
314 } else {
315 DEB2("NOT ACK sent after data byte received. "
316 "Not final byte. numbytes %d. len %d\n",
317 numbytes, msg->len);
318 pca_stop(adap);
319 goto out;
320 }
321 break;
322 case 0x70: /* Bus error - SDA stuck low */
323 DEB2("BUS ERROR - SDA Stuck low\n");
324 pca_reset(adap);
325 goto out;
326 case 0x90: /* Bus error - SCL stuck low */
327 DEB2("BUS ERROR - SCL Stuck low\n");
328 pca_reset(adap);
329 goto out;
330 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
331 DEB2("BUS ERROR - Illegal START or STOP\n");
332 pca_reset(adap);
333 goto out;
334 default:
335 dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
336 break;
337 }
338
339 if (!completed)
340 goto out;
341 }
342
343 ret = curmsg;
344 out:
345 DEB1("}}} transferred %d/%d messages. "
346 "status is %#04x. control is %#04x\n",
347 curmsg, num, pca_status(adap),
348 pca_get_con(adap));
349 return ret;
350 }
351
pca_func(struct i2c_adapter * adap)352 static u32 pca_func(struct i2c_adapter *adap)
353 {
354 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
355 }
356
357 static const struct i2c_algorithm pca_algo = {
358 .master_xfer = pca_xfer,
359 .functionality = pca_func,
360 };
361
pca_probe_chip(struct i2c_adapter * adap)362 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
363 {
364 struct i2c_algo_pca_data *pca_data = adap->algo_data;
365 /* The trick here is to check if there is an indirect register
366 * available. If there is one, we will read the value we first
367 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
368 * we wrote on I2C_PCA_ADR
369 */
370 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
371 pca_outw(pca_data, I2C_PCA_IND, 0xAA);
372 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
373 pca_outw(pca_data, I2C_PCA_IND, 0x00);
374 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
375 if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
376 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
377 pca_data->chip = I2C_PCA_CHIP_9665;
378 } else {
379 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
380 pca_data->chip = I2C_PCA_CHIP_9564;
381 }
382 return pca_data->chip;
383 }
384
pca_init(struct i2c_adapter * adap)385 static int pca_init(struct i2c_adapter *adap)
386 {
387 struct i2c_algo_pca_data *pca_data = adap->algo_data;
388
389 adap->algo = &pca_algo;
390
391 if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
392 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
393 int clock;
394
395 if (pca_data->i2c_clock > 7) {
396 switch (pca_data->i2c_clock) {
397 case 330000:
398 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
399 break;
400 case 288000:
401 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
402 break;
403 case 217000:
404 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
405 break;
406 case 146000:
407 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
408 break;
409 case 88000:
410 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
411 break;
412 case 59000:
413 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
414 break;
415 case 44000:
416 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
417 break;
418 case 36000:
419 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
420 break;
421 default:
422 printk(KERN_WARNING
423 "%s: Invalid I2C clock speed selected."
424 " Using default 59kHz.\n", adap->name);
425 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
426 }
427 } else {
428 printk(KERN_WARNING "%s: "
429 "Choosing the clock frequency based on "
430 "index is deprecated."
431 " Use the nominal frequency.\n", adap->name);
432 }
433
434 pca_reset(pca_data);
435
436 clock = pca_clock(pca_data);
437 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
438 adap->name, freqs[clock]);
439
440 pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
441 } else {
442 int clock;
443 int mode;
444 int tlow, thi;
445 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
446 int min_tlow, min_thi;
447 /* These values are the maximum raise and fall values allowed
448 * by the I2C operation mode (Standard, Fast or Fast+)
449 * They are used (added) below to calculate the clock dividers
450 * of PCA9665. Note that they are slightly different of the
451 * real maximum, to allow the change on mode exactly on the
452 * maximum clock rate for each mode
453 */
454 int raise_fall_time;
455
456 if (pca_data->i2c_clock > 1265800) {
457 printk(KERN_WARNING "%s: I2C clock speed too high."
458 " Using 1265.8kHz.\n", adap->name);
459 pca_data->i2c_clock = 1265800;
460 }
461
462 if (pca_data->i2c_clock < 60300) {
463 printk(KERN_WARNING "%s: I2C clock speed too low."
464 " Using 60.3kHz.\n", adap->name);
465 pca_data->i2c_clock = 60300;
466 }
467
468 /* To avoid integer overflow, use clock/100 for calculations */
469 clock = pca_clock(pca_data) / 100;
470
471 if (pca_data->i2c_clock > 1000000) {
472 mode = I2C_PCA_MODE_TURBO;
473 min_tlow = 14;
474 min_thi = 5;
475 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
476 } else if (pca_data->i2c_clock > 400000) {
477 mode = I2C_PCA_MODE_FASTP;
478 min_tlow = 17;
479 min_thi = 9;
480 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
481 } else if (pca_data->i2c_clock > 100000) {
482 mode = I2C_PCA_MODE_FAST;
483 min_tlow = 44;
484 min_thi = 20;
485 raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
486 } else {
487 mode = I2C_PCA_MODE_STD;
488 min_tlow = 157;
489 min_thi = 134;
490 raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
491 }
492
493 /* The minimum clock that respects the thi/tlow = 134/157 is
494 * 64800 Hz. Below that, we have to fix the tlow to 255 and
495 * calculate the thi factor.
496 */
497 if (clock < 648) {
498 tlow = 255;
499 thi = 1000000 - clock * raise_fall_time;
500 thi /= (I2C_PCA_OSC_PER * clock) - tlow;
501 } else {
502 tlow = (1000000 - clock * raise_fall_time) * min_tlow;
503 tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
504 thi = tlow * min_thi / min_tlow;
505 }
506
507 pca_reset(pca_data);
508
509 printk(KERN_INFO
510 "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
511
512 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
513 pca_outw(pca_data, I2C_PCA_IND, mode);
514 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
515 pca_outw(pca_data, I2C_PCA_IND, tlow);
516 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
517 pca_outw(pca_data, I2C_PCA_IND, thi);
518
519 pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
520 }
521 udelay(500); /* 500 us for oscillator to stabilise */
522
523 return 0;
524 }
525
526 /*
527 * registering functions to load algorithms at runtime
528 */
i2c_pca_add_bus(struct i2c_adapter * adap)529 int i2c_pca_add_bus(struct i2c_adapter *adap)
530 {
531 int rval;
532
533 rval = pca_init(adap);
534 if (rval)
535 return rval;
536
537 return i2c_add_adapter(adap);
538 }
539 EXPORT_SYMBOL(i2c_pca_add_bus);
540
i2c_pca_add_numbered_bus(struct i2c_adapter * adap)541 int i2c_pca_add_numbered_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_numbered_adapter(adap);
550 }
551 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
552
553 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
554 "Wolfram Sang <w.sang@pengutronix.de>");
555 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
556 MODULE_LICENSE("GPL");
557
558 module_param(i2c_debug, int, 0);
559
