1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
4 * Copyright (C) 2004 Arcom Control Systems
5 * Copyright (C) 2008 Pengutronix
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/delay.h>
12 #include <linux/jiffies.h>
13 #include <linux/errno.h>
14 #include <linux/i2c.h>
15 #include <linux/i2c-algo-pca.h>
16
17 #define DEB1(fmt, args...) do { if (i2c_debug >= 1) \
18 printk(KERN_DEBUG fmt, ## args); } while (0)
19 #define DEB2(fmt, args...) do { if (i2c_debug >= 2) \
20 printk(KERN_DEBUG fmt, ## args); } while (0)
21 #define DEB3(fmt, args...) do { if (i2c_debug >= 3) \
22 printk(KERN_DEBUG fmt, ## args); } while (0)
23
24 static int i2c_debug;
25
26 #define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
27 #define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
28
29 #define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
30 #define pca_clock(adap) adap->i2c_clock
31 #define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
32 #define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
33 #define pca_wait(adap) adap->wait_for_completion(adap->data)
34
pca_reset(struct i2c_algo_pca_data * adap)35 static void pca_reset(struct i2c_algo_pca_data *adap)
36 {
37 if (adap->chip == I2C_PCA_CHIP_9665) {
38 /* Ignore the reset function from the module,
39 * we can use the parallel bus reset.
40 */
41 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
42 pca_outw(adap, I2C_PCA_IND, 0xA5);
43 pca_outw(adap, I2C_PCA_IND, 0x5A);
44
45 /*
46 * After a reset we need to re-apply any configuration
47 * (calculated in pca_init) to get the bus in a working state.
48 */
49 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE);
50 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode);
51 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
52 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow);
53 pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
54 pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi);
55
56 pca_set_con(adap, I2C_PCA_CON_ENSIO);
57 } else {
58 adap->reset_chip(adap->data);
59 pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq);
60 }
61 }
62
63 /*
64 * Generate a start condition on the i2c bus.
65 *
66 * returns after the start condition has occurred
67 */
pca_start(struct i2c_algo_pca_data * adap)68 static int pca_start(struct i2c_algo_pca_data *adap)
69 {
70 int sta = pca_get_con(adap);
71 DEB2("=== START\n");
72 sta |= I2C_PCA_CON_STA;
73 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
74 pca_set_con(adap, sta);
75 return pca_wait(adap);
76 }
77
78 /*
79 * Generate a repeated start condition on the i2c bus
80 *
81 * return after the repeated start condition has occurred
82 */
pca_repeated_start(struct i2c_algo_pca_data * adap)83 static int pca_repeated_start(struct i2c_algo_pca_data *adap)
84 {
85 int sta = pca_get_con(adap);
86 DEB2("=== REPEATED START\n");
87 sta |= I2C_PCA_CON_STA;
88 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
89 pca_set_con(adap, sta);
90 return pca_wait(adap);
91 }
92
93 /*
94 * Generate a stop condition on the i2c bus
95 *
96 * returns after the stop condition has been generated
97 *
98 * STOPs do not generate an interrupt or set the SI flag, since the
99 * part returns the idle state (0xf8). Hence we don't need to
100 * pca_wait here.
101 */
pca_stop(struct i2c_algo_pca_data * adap)102 static void pca_stop(struct i2c_algo_pca_data *adap)
103 {
104 int sta = pca_get_con(adap);
105 DEB2("=== STOP\n");
106 sta |= I2C_PCA_CON_STO;
107 sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
108 pca_set_con(adap, sta);
109 }
110
111 /*
112 * Send the slave address and R/W bit
113 *
114 * returns after the address has been sent
115 */
pca_address(struct i2c_algo_pca_data * adap,struct i2c_msg * msg)116 static int pca_address(struct i2c_algo_pca_data *adap,
117 struct i2c_msg *msg)
118 {
119 int sta = pca_get_con(adap);
120 int addr = i2c_8bit_addr_from_msg(msg);
121
122 DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
123 msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
124
125 pca_outw(adap, I2C_PCA_DAT, addr);
126
127 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
128 pca_set_con(adap, sta);
129
130 return pca_wait(adap);
131 }
132
133 /*
134 * Transmit a byte.
135 *
136 * Returns after the byte has been transmitted
137 */
pca_tx_byte(struct i2c_algo_pca_data * adap,__u8 b)138 static int pca_tx_byte(struct i2c_algo_pca_data *adap,
139 __u8 b)
140 {
141 int sta = pca_get_con(adap);
142 DEB2("=== WRITE %#04x\n", b);
143 pca_outw(adap, I2C_PCA_DAT, b);
144
145 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
146 pca_set_con(adap, sta);
147
148 return pca_wait(adap);
149 }
150
151 /*
152 * Receive a byte
153 *
154 * returns immediately.
155 */
pca_rx_byte(struct i2c_algo_pca_data * adap,__u8 * b,int ack)156 static void pca_rx_byte(struct i2c_algo_pca_data *adap,
157 __u8 *b, int ack)
158 {
159 *b = pca_inw(adap, I2C_PCA_DAT);
160 DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
161 }
162
163 /*
164 * Setup ACK or NACK for next received byte and wait for it to arrive.
165 *
166 * Returns after next byte has arrived.
167 */
pca_rx_ack(struct i2c_algo_pca_data * adap,int ack)168 static int pca_rx_ack(struct i2c_algo_pca_data *adap,
169 int ack)
170 {
171 int sta = pca_get_con(adap);
172
173 sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
174
175 if (ack)
176 sta |= I2C_PCA_CON_AA;
177
178 pca_set_con(adap, sta);
179 return pca_wait(adap);
180 }
181
pca_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)182 static int pca_xfer(struct i2c_adapter *i2c_adap,
183 struct i2c_msg *msgs,
184 int num)
185 {
186 struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
187 struct i2c_msg *msg = NULL;
188 int curmsg;
189 int numbytes = 0;
190 int state;
191 int ret;
192 int completed = 1;
193 unsigned long timeout = jiffies + i2c_adap->timeout;
194
195 while ((state = pca_status(adap)) != 0xf8) {
196 if (time_before(jiffies, timeout)) {
197 msleep(10);
198 } else {
199 dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
200 "%#04x\n", state);
201 return -EBUSY;
202 }
203 }
204
205 DEB1("{{{ XFER %d messages\n", num);
206
207 if (i2c_debug >= 2) {
208 for (curmsg = 0; curmsg < num; curmsg++) {
209 int addr, i;
210 msg = &msgs[curmsg];
211
212 addr = (0x7f & msg->addr) ;
213
214 if (msg->flags & I2C_M_RD)
215 printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
216 curmsg, msg->len, addr, (addr << 1) | 1);
217 else {
218 printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s",
219 curmsg, msg->len, addr, addr << 1,
220 msg->len == 0 ? "" : ", ");
221 for (i = 0; i < msg->len; i++)
222 printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
223 printk("]\n");
224 }
225 }
226 }
227
228 curmsg = 0;
229 ret = -EIO;
230 while (curmsg < num) {
231 state = pca_status(adap);
232
233 DEB3("STATE is 0x%02x\n", state);
234 msg = &msgs[curmsg];
235
236 switch (state) {
237 case 0xf8: /* On reset or stop the bus is idle */
238 completed = pca_start(adap);
239 break;
240
241 case 0x08: /* A START condition has been transmitted */
242 case 0x10: /* A repeated start condition has been transmitted */
243 completed = pca_address(adap, msg);
244 break;
245
246 case 0x18: /* SLA+W has been transmitted; ACK has been received */
247 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
248 if (numbytes < msg->len) {
249 completed = pca_tx_byte(adap,
250 msg->buf[numbytes]);
251 numbytes++;
252 break;
253 }
254 curmsg++; numbytes = 0;
255 if (curmsg == num)
256 pca_stop(adap);
257 else
258 completed = pca_repeated_start(adap);
259 break;
260
261 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
262 DEB2("NOT ACK received after SLA+W\n");
263 pca_stop(adap);
264 ret = -ENXIO;
265 goto out;
266
267 case 0x40: /* SLA+R has been transmitted; ACK has been received */
268 completed = pca_rx_ack(adap, msg->len > 1);
269 break;
270
271 case 0x50: /* Data bytes has been received; ACK has been returned */
272 if (numbytes < msg->len) {
273 pca_rx_byte(adap, &msg->buf[numbytes], 1);
274 numbytes++;
275 completed = pca_rx_ack(adap,
276 numbytes < msg->len - 1);
277 break;
278 }
279 curmsg++; numbytes = 0;
280 if (curmsg == num)
281 pca_stop(adap);
282 else
283 completed = pca_repeated_start(adap);
284 break;
285
286 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
287 DEB2("NOT ACK received after SLA+R\n");
288 pca_stop(adap);
289 ret = -ENXIO;
290 goto out;
291
292 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
293 DEB2("NOT ACK received after data byte\n");
294 pca_stop(adap);
295 goto out;
296
297 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
298 DEB2("Arbitration lost\n");
299 /*
300 * The PCA9564 data sheet (2006-09-01) says "A
301 * START condition will be transmitted when the
302 * bus becomes free (STOP or SCL and SDA high)"
303 * when the STA bit is set (p. 11).
304 *
305 * In case this won't work, try pca_reset()
306 * instead.
307 */
308 pca_start(adap);
309 goto out;
310
311 case 0x58: /* Data byte has been received; NOT ACK has been returned */
312 if (numbytes == msg->len - 1) {
313 pca_rx_byte(adap, &msg->buf[numbytes], 0);
314 curmsg++; numbytes = 0;
315 if (curmsg == num)
316 pca_stop(adap);
317 else
318 completed = pca_repeated_start(adap);
319 } else {
320 DEB2("NOT ACK sent after data byte received. "
321 "Not final byte. numbytes %d. len %d\n",
322 numbytes, msg->len);
323 pca_stop(adap);
324 goto out;
325 }
326 break;
327 case 0x70: /* Bus error - SDA stuck low */
328 DEB2("BUS ERROR - SDA Stuck low\n");
329 pca_reset(adap);
330 goto out;
331 case 0x78: /* Bus error - SCL stuck low (PCA9665) */
332 case 0x90: /* Bus error - SCL stuck low (PCA9564) */
333 DEB2("BUS ERROR - SCL Stuck low\n");
334 pca_reset(adap);
335 goto out;
336 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
337 DEB2("BUS ERROR - Illegal START or STOP\n");
338 pca_reset(adap);
339 goto out;
340 default:
341 dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
342 break;
343 }
344
345 if (!completed)
346 goto out;
347 }
348
349 ret = curmsg;
350 out:
351 DEB1("}}} transferred %d/%d messages. "
352 "status is %#04x. control is %#04x\n",
353 curmsg, num, pca_status(adap),
354 pca_get_con(adap));
355 return ret;
356 }
357
pca_func(struct i2c_adapter * adap)358 static u32 pca_func(struct i2c_adapter *adap)
359 {
360 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
361 }
362
363 static const struct i2c_algorithm pca_algo = {
364 .master_xfer = pca_xfer,
365 .functionality = pca_func,
366 };
367
pca_probe_chip(struct i2c_adapter * adap)368 static unsigned int pca_probe_chip(struct i2c_adapter *adap)
369 {
370 struct i2c_algo_pca_data *pca_data = adap->algo_data;
371 /* The trick here is to check if there is an indirect register
372 * available. If there is one, we will read the value we first
373 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
374 * we wrote on I2C_PCA_ADR
375 */
376 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
377 pca_outw(pca_data, I2C_PCA_IND, 0xAA);
378 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
379 pca_outw(pca_data, I2C_PCA_IND, 0x00);
380 pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
381 if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
382 printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
383 pca_data->chip = I2C_PCA_CHIP_9665;
384 } else {
385 printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
386 pca_data->chip = I2C_PCA_CHIP_9564;
387 }
388 return pca_data->chip;
389 }
390
pca_init(struct i2c_adapter * adap)391 static int pca_init(struct i2c_adapter *adap)
392 {
393 struct i2c_algo_pca_data *pca_data = adap->algo_data;
394
395 adap->algo = &pca_algo;
396
397 if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
398 static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
399 int clock;
400
401 if (pca_data->i2c_clock > 7) {
402 switch (pca_data->i2c_clock) {
403 case 330000:
404 pca_data->i2c_clock = I2C_PCA_CON_330kHz;
405 break;
406 case 288000:
407 pca_data->i2c_clock = I2C_PCA_CON_288kHz;
408 break;
409 case 217000:
410 pca_data->i2c_clock = I2C_PCA_CON_217kHz;
411 break;
412 case 146000:
413 pca_data->i2c_clock = I2C_PCA_CON_146kHz;
414 break;
415 case 88000:
416 pca_data->i2c_clock = I2C_PCA_CON_88kHz;
417 break;
418 case 59000:
419 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
420 break;
421 case 44000:
422 pca_data->i2c_clock = I2C_PCA_CON_44kHz;
423 break;
424 case 36000:
425 pca_data->i2c_clock = I2C_PCA_CON_36kHz;
426 break;
427 default:
428 printk(KERN_WARNING
429 "%s: Invalid I2C clock speed selected."
430 " Using default 59kHz.\n", adap->name);
431 pca_data->i2c_clock = I2C_PCA_CON_59kHz;
432 }
433 } else {
434 printk(KERN_WARNING "%s: "
435 "Choosing the clock frequency based on "
436 "index is deprecated."
437 " Use the nominal frequency.\n", adap->name);
438 }
439
440 clock = pca_clock(pca_data);
441 printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
442 adap->name, freqs[clock]);
443
444 /* Store settings as these will be needed when the PCA chip is reset */
445 pca_data->bus_settings.clock_freq = clock;
446
447 pca_reset(pca_data);
448 } else {
449 int clock;
450 int mode;
451 int tlow, thi;
452 /* Values can be found on PCA9665 datasheet section 7.3.2.6 */
453 int min_tlow, min_thi;
454 /* These values are the maximum raise and fall values allowed
455 * by the I2C operation mode (Standard, Fast or Fast+)
456 * They are used (added) below to calculate the clock dividers
457 * of PCA9665. Note that they are slightly different of the
458 * real maximum, to allow the change on mode exactly on the
459 * maximum clock rate for each mode
460 */
461 int raise_fall_time;
462
463 if (pca_data->i2c_clock > 1265800) {
464 printk(KERN_WARNING "%s: I2C clock speed too high."
465 " Using 1265.8kHz.\n", adap->name);
466 pca_data->i2c_clock = 1265800;
467 }
468
469 if (pca_data->i2c_clock < 60300) {
470 printk(KERN_WARNING "%s: I2C clock speed too low."
471 " Using 60.3kHz.\n", adap->name);
472 pca_data->i2c_clock = 60300;
473 }
474
475 /* To avoid integer overflow, use clock/100 for calculations */
476 clock = pca_clock(pca_data) / 100;
477
478 if (pca_data->i2c_clock > I2C_MAX_FAST_MODE_PLUS_FREQ) {
479 mode = I2C_PCA_MODE_TURBO;
480 min_tlow = 14;
481 min_thi = 5;
482 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
483 } else if (pca_data->i2c_clock > I2C_MAX_FAST_MODE_FREQ) {
484 mode = I2C_PCA_MODE_FASTP;
485 min_tlow = 17;
486 min_thi = 9;
487 raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
488 } else if (pca_data->i2c_clock > I2C_MAX_STANDARD_MODE_FREQ) {
489 mode = I2C_PCA_MODE_FAST;
490 min_tlow = 44;
491 min_thi = 20;
492 raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
493 } else {
494 mode = I2C_PCA_MODE_STD;
495 min_tlow = 157;
496 min_thi = 134;
497 raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
498 }
499
500 /* The minimum clock that respects the thi/tlow = 134/157 is
501 * 64800 Hz. Below that, we have to fix the tlow to 255 and
502 * calculate the thi factor.
503 */
504 if (clock < 648) {
505 tlow = 255;
506 thi = 1000000 - clock * raise_fall_time;
507 thi /= (I2C_PCA_OSC_PER * clock) - tlow;
508 } else {
509 tlow = (1000000 - clock * raise_fall_time) * min_tlow;
510 tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
511 thi = tlow * min_thi / min_tlow;
512 }
513
514 /* Store settings as these will be needed when the PCA chip is reset */
515 pca_data->bus_settings.mode = mode;
516 pca_data->bus_settings.tlow = tlow;
517 pca_data->bus_settings.thi = thi;
518
519 pca_reset(pca_data);
520
521 printk(KERN_INFO
522 "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
523 }
524 udelay(500); /* 500 us for oscillator to stabilise */
525
526 return 0;
527 }
528
529 /*
530 * registering functions to load algorithms at runtime
531 */
i2c_pca_add_bus(struct i2c_adapter * adap)532 int i2c_pca_add_bus(struct i2c_adapter *adap)
533 {
534 int rval;
535
536 rval = pca_init(adap);
537 if (rval)
538 return rval;
539
540 return i2c_add_adapter(adap);
541 }
542 EXPORT_SYMBOL(i2c_pca_add_bus);
543
i2c_pca_add_numbered_bus(struct i2c_adapter * adap)544 int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
545 {
546 int rval;
547
548 rval = pca_init(adap);
549 if (rval)
550 return rval;
551
552 return i2c_add_numbered_adapter(adap);
553 }
554 EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
555
556 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
557 MODULE_AUTHOR("Wolfram Sang <kernel@pengutronix.de>");
558 MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
559 MODULE_LICENSE("GPL");
560
561 module_param(i2c_debug, int, 0);
562