1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
4 *
5 * Copyright (C) 1995-1997 Simon G. Vogl
6 * 1998-2000 Hans Berglund
7 *
8 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
9 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
10 * <mbailey@littlefeet-inc.com>
11 *
12 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
13 * messages, proper stop/repstart signaling during receive, added detect code
14 */
15
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/delay.h>
19 #include <linux/errno.h>
20 #include <linux/i2c.h>
21 #include <linux/i2c-algo-pcf.h>
22 #include <linux/string_choices.h>
23 #include "i2c-algo-pcf.h"
24
25
26 #define DEB2(x) if (i2c_debug >= 2) x
27 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
28 #define DEBPROTO(x) if (i2c_debug >= 9) x;
29 /* debug the protocol by showing transferred bits */
30 #define DEF_TIMEOUT 16
31
32 /*
33 * module parameters:
34 */
35 static int i2c_debug;
36
37 /* setting states on the bus with the right timing: */
38
39 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
40 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
41 #define get_own(adap) adap->getown(adap->data)
42 #define get_clock(adap) adap->getclock(adap->data)
43 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
44 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
45
46 /* other auxiliary functions */
47
i2c_start(struct i2c_algo_pcf_data * adap)48 static void i2c_start(struct i2c_algo_pcf_data *adap)
49 {
50 DEBPROTO(printk(KERN_DEBUG "S "));
51 set_pcf(adap, 1, I2C_PCF_START);
52 }
53
i2c_repstart(struct i2c_algo_pcf_data * adap)54 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
55 {
56 DEBPROTO(printk(" Sr "));
57 set_pcf(adap, 1, I2C_PCF_REPSTART);
58 }
59
i2c_stop(struct i2c_algo_pcf_data * adap)60 static void i2c_stop(struct i2c_algo_pcf_data *adap)
61 {
62 DEBPROTO(printk("P\n"));
63 set_pcf(adap, 1, I2C_PCF_STOP);
64 }
65
handle_lab(struct i2c_algo_pcf_data * adap,const int * status)66 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
67 {
68 DEB2(printk(KERN_INFO
69 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
70 *status));
71 /*
72 * Cleanup from LAB -- reset and enable ESO.
73 * This resets the PCF8584; since we've lost the bus, no
74 * further attempts should be made by callers to clean up
75 * (no i2c_stop() etc.)
76 */
77 set_pcf(adap, 1, I2C_PCF_PIN);
78 set_pcf(adap, 1, I2C_PCF_ESO);
79 /*
80 * We pause for a time period sufficient for any running
81 * I2C transaction to complete -- the arbitration logic won't
82 * work properly until the next START is seen.
83 * It is assumed the bus driver or client has set a proper value.
84 *
85 * REVISIT: should probably use msleep instead of mdelay if we
86 * know we can sleep.
87 */
88 if (adap->lab_mdelay)
89 mdelay(adap->lab_mdelay);
90
91 DEB2(printk(KERN_INFO
92 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
93 get_pcf(adap, 1)));
94 }
95
wait_for_bb(struct i2c_algo_pcf_data * adap)96 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
97 {
98
99 int timeout = DEF_TIMEOUT;
100 int status;
101
102 status = get_pcf(adap, 1);
103
104 while (!(status & I2C_PCF_BB) && --timeout) {
105 udelay(100); /* wait for 100 us */
106 status = get_pcf(adap, 1);
107 }
108
109 if (timeout == 0) {
110 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
111 return -ETIMEDOUT;
112 }
113
114 return 0;
115 }
116
wait_for_pin(struct i2c_algo_pcf_data * adap,int * status)117 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
118 {
119
120 int timeout = DEF_TIMEOUT;
121
122 *status = get_pcf(adap, 1);
123
124 while ((*status & I2C_PCF_PIN) && --timeout) {
125 adap->waitforpin(adap->data);
126 *status = get_pcf(adap, 1);
127 }
128 if (*status & I2C_PCF_LAB) {
129 handle_lab(adap, status);
130 return -EINTR;
131 }
132
133 if (timeout == 0)
134 return -ETIMEDOUT;
135
136 return 0;
137 }
138
139 /*
140 * This should perform the 'PCF8584 initialization sequence' as described
141 * in the Philips IC12 data book (1995, Aug 29).
142 * There should be a 30 clock cycle wait after reset, I assume this
143 * has been fulfilled.
144 * There should be a delay at the end equal to the longest I2C message
145 * to synchronize the BB-bit (in multimaster systems). How long is
146 * this? I assume 1 second is always long enough.
147 *
148 * vdovikin: added detect code for PCF8584
149 */
pcf_init_8584(struct i2c_algo_pcf_data * adap)150 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
151 {
152 unsigned char temp;
153
154 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
155 get_pcf(adap, 1)));
156
157 /* S1=0x80: S0 selected, serial interface off */
158 set_pcf(adap, 1, I2C_PCF_PIN);
159 /*
160 * check to see S1 now used as R/W ctrl -
161 * PCF8584 does that when ESO is zero
162 */
163 if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
164 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
165 return -ENXIO; /* definitely not PCF8584 */
166 }
167
168 /* load own address in S0, effective address is (own << 1) */
169 i2c_outb(adap, get_own(adap));
170 /* check it's really written */
171 if ((temp = i2c_inb(adap)) != get_own(adap)) {
172 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
173 return -ENXIO;
174 }
175
176 /* S1=0xA0, next byte in S2 */
177 set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
178 /* check to see S2 now selected */
179 if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
180 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
181 return -ENXIO;
182 }
183
184 /* load clock register S2 */
185 i2c_outb(adap, get_clock(adap));
186 /* check it's really written, the only 5 lowest bits does matter */
187 if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
188 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
189 return -ENXIO;
190 }
191
192 /* Enable serial interface, idle, S0 selected */
193 set_pcf(adap, 1, I2C_PCF_IDLE);
194
195 /* check to see PCF is really idled and we can access status register */
196 if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
197 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
198 return -ENXIO;
199 }
200
201 printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
202
203 return 0;
204 }
205
pcf_sendbytes(struct i2c_adapter * i2c_adap,const char * buf,int count,int last)206 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
207 int count, int last)
208 {
209 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
210 int wrcount, status, timeout;
211
212 for (wrcount=0; wrcount<count; ++wrcount) {
213 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
214 buf[wrcount] & 0xff));
215 i2c_outb(adap, buf[wrcount]);
216 timeout = wait_for_pin(adap, &status);
217 if (timeout) {
218 if (timeout == -EINTR)
219 return -EINTR; /* arbitration lost */
220
221 i2c_stop(adap);
222 dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
223 return -EREMOTEIO; /* got a better one ?? */
224 }
225 if (status & I2C_PCF_LRB) {
226 i2c_stop(adap);
227 dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
228 return -EREMOTEIO; /* got a better one ?? */
229 }
230 }
231 if (last)
232 i2c_stop(adap);
233 else
234 i2c_repstart(adap);
235
236 return wrcount;
237 }
238
pcf_readbytes(struct i2c_adapter * i2c_adap,char * buf,int count,int last)239 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
240 int count, int last)
241 {
242 int i, status;
243 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
244 int wfp;
245
246 /* increment number of bytes to read by one -- read dummy byte */
247 for (i = 0; i <= count; i++) {
248
249 if ((wfp = wait_for_pin(adap, &status))) {
250 if (wfp == -EINTR)
251 return -EINTR; /* arbitration lost */
252
253 i2c_stop(adap);
254 dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
255 return -1;
256 }
257
258 if ((status & I2C_PCF_LRB) && (i != count)) {
259 i2c_stop(adap);
260 dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
261 return -1;
262 }
263
264 if (i == count - 1) {
265 set_pcf(adap, 1, I2C_PCF_ESO);
266 } else if (i == count) {
267 if (last)
268 i2c_stop(adap);
269 else
270 i2c_repstart(adap);
271 }
272
273 if (i)
274 buf[i - 1] = i2c_inb(adap);
275 else
276 i2c_inb(adap); /* dummy read */
277 }
278
279 return i - 1;
280 }
281
282
pcf_doAddress(struct i2c_algo_pcf_data * adap,struct i2c_msg * msg)283 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
284 struct i2c_msg *msg)
285 {
286 unsigned char addr = i2c_8bit_addr_from_msg(msg);
287
288 if (msg->flags & I2C_M_REV_DIR_ADDR)
289 addr ^= 1;
290 i2c_outb(adap, addr);
291
292 return 0;
293 }
294
pcf_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)295 static int pcf_xfer(struct i2c_adapter *i2c_adap,
296 struct i2c_msg *msgs,
297 int num)
298 {
299 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
300 struct i2c_msg *pmsg;
301 int i;
302 int ret=0, timeout, status;
303
304 if (adap->xfer_begin)
305 adap->xfer_begin(adap->data);
306
307 /* Check for bus busy */
308 timeout = wait_for_bb(adap);
309 if (timeout) {
310 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
311 "Timeout waiting for BB in pcf_xfer\n");)
312 i = -EIO;
313 goto out;
314 }
315
316 for (i = 0;ret >= 0 && i < num; i++) {
317 pmsg = &msgs[i];
318
319 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
320 str_read_write(pmsg->flags & I2C_M_RD),
321 pmsg->len, pmsg->addr, i + 1, num);)
322
323 ret = pcf_doAddress(adap, pmsg);
324
325 /* Send START */
326 if (i == 0)
327 i2c_start(adap);
328
329 /* Wait for PIN (pending interrupt NOT) */
330 timeout = wait_for_pin(adap, &status);
331 if (timeout) {
332 if (timeout == -EINTR) {
333 /* arbitration lost */
334 i = -EINTR;
335 goto out;
336 }
337 i2c_stop(adap);
338 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
339 "for PIN(1) in pcf_xfer\n");)
340 i = -EREMOTEIO;
341 goto out;
342 }
343
344 /* Check LRB (last rcvd bit - slave ack) */
345 if (status & I2C_PCF_LRB) {
346 i2c_stop(adap);
347 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
348 i = -EREMOTEIO;
349 goto out;
350 }
351
352 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
353 i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
354
355 if (pmsg->flags & I2C_M_RD) {
356 ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
357 (i + 1 == num));
358
359 if (ret != pmsg->len) {
360 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
361 "only read %d bytes.\n",ret));
362 } else {
363 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
364 }
365 } else {
366 ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
367 (i + 1 == num));
368
369 if (ret != pmsg->len) {
370 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
371 "only wrote %d bytes.\n",ret));
372 } else {
373 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
374 }
375 }
376 }
377
378 out:
379 if (adap->xfer_end)
380 adap->xfer_end(adap->data);
381 return i;
382 }
383
pcf_func(struct i2c_adapter * adap)384 static u32 pcf_func(struct i2c_adapter *adap)
385 {
386 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
387 I2C_FUNC_PROTOCOL_MANGLING;
388 }
389
390 /* exported algorithm data: */
391 static const struct i2c_algorithm pcf_algo = {
392 .xfer = pcf_xfer,
393 .functionality = pcf_func,
394 };
395
396 /*
397 * registering functions to load algorithms at runtime
398 */
i2c_pcf_add_bus(struct i2c_adapter * adap)399 int i2c_pcf_add_bus(struct i2c_adapter *adap)
400 {
401 struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
402 int rval;
403
404 DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
405
406 /* register new adapter to i2c module... */
407 adap->algo = &pcf_algo;
408
409 if ((rval = pcf_init_8584(pcf_adap)))
410 return rval;
411
412 rval = i2c_add_adapter(adap);
413
414 return rval;
415 }
416 EXPORT_SYMBOL(i2c_pcf_add_bus);
417
418 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
419 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
420 MODULE_LICENSE("GPL");
421
422 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
423 MODULE_PARM_DESC(i2c_debug,
424 "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
425