treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
[sfrench/cifs-2.6.git] / drivers / i2c / algos / i2c-algo-pcf.c
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 "i2c-algo-pcf.h"
23
24
25 #define DEB2(x) if (i2c_debug >= 2) x
26 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
27 #define DEBPROTO(x) if (i2c_debug >= 9) x;
28         /* debug the protocol by showing transferred bits */
29 #define DEF_TIMEOUT 16
30
31 /*
32  * module parameters:
33  */
34 static int i2c_debug;
35
36 /* setting states on the bus with the right timing: */
37
38 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
39 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
40 #define get_own(adap) adap->getown(adap->data)
41 #define get_clock(adap) adap->getclock(adap->data)
42 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
43 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
44
45 /* other auxiliary functions */
46
47 static void i2c_start(struct i2c_algo_pcf_data *adap)
48 {
49         DEBPROTO(printk(KERN_DEBUG "S "));
50         set_pcf(adap, 1, I2C_PCF_START);
51 }
52
53 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
54 {
55         DEBPROTO(printk(" Sr "));
56         set_pcf(adap, 1, I2C_PCF_REPSTART);
57 }
58
59 static void i2c_stop(struct i2c_algo_pcf_data *adap)
60 {
61         DEBPROTO(printk("P\n"));
62         set_pcf(adap, 1, I2C_PCF_STOP);
63 }
64
65 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
66 {
67         DEB2(printk(KERN_INFO
68                 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
69                 *status));
70         /*
71          * Cleanup from LAB -- reset and enable ESO.
72          * This resets the PCF8584; since we've lost the bus, no
73          * further attempts should be made by callers to clean up
74          * (no i2c_stop() etc.)
75          */
76         set_pcf(adap, 1, I2C_PCF_PIN);
77         set_pcf(adap, 1, I2C_PCF_ESO);
78         /*
79          * We pause for a time period sufficient for any running
80          * I2C transaction to complete -- the arbitration logic won't
81          * work properly until the next START is seen.
82          * It is assumed the bus driver or client has set a proper value.
83          *
84          * REVISIT: should probably use msleep instead of mdelay if we
85          * know we can sleep.
86          */
87         if (adap->lab_mdelay)
88                 mdelay(adap->lab_mdelay);
89
90         DEB2(printk(KERN_INFO
91                 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
92                 get_pcf(adap, 1)));
93 }
94
95 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
96 {
97
98         int timeout = DEF_TIMEOUT;
99         int status;
100
101         status = get_pcf(adap, 1);
102
103         while (!(status & I2C_PCF_BB) && --timeout) {
104                 udelay(100); /* wait for 100 us */
105                 status = get_pcf(adap, 1);
106         }
107
108         if (timeout == 0) {
109                 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
110                 return -ETIMEDOUT;
111         }
112
113         return 0;
114 }
115
116 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
117 {
118
119         int timeout = DEF_TIMEOUT;
120
121         *status = get_pcf(adap, 1);
122
123         while ((*status & I2C_PCF_PIN) && --timeout) {
124                 adap->waitforpin(adap->data);
125                 *status = get_pcf(adap, 1);
126         }
127         if (*status & I2C_PCF_LAB) {
128                 handle_lab(adap, status);
129                 return -EINTR;
130         }
131
132         if (timeout == 0)
133                 return -ETIMEDOUT;
134
135         return 0;
136 }
137
138 /*
139  * This should perform the 'PCF8584 initialization sequence' as described
140  * in the Philips IC12 data book (1995, Aug 29).
141  * There should be a 30 clock cycle wait after reset, I assume this
142  * has been fulfilled.
143  * There should be a delay at the end equal to the longest I2C message
144  * to synchronize the BB-bit (in multimaster systems). How long is
145  * this? I assume 1 second is always long enough.
146  *
147  * vdovikin: added detect code for PCF8584
148  */
149 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
150 {
151         unsigned char temp;
152
153         DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
154                                 get_pcf(adap, 1)));
155
156         /* S1=0x80: S0 selected, serial interface off */
157         set_pcf(adap, 1, I2C_PCF_PIN);
158         /*
159          * check to see S1 now used as R/W ctrl -
160          * PCF8584 does that when ESO is zero
161          */
162         if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
163                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
164                 return -ENXIO; /* definitely not PCF8584 */
165         }
166
167         /* load own address in S0, effective address is (own << 1) */
168         i2c_outb(adap, get_own(adap));
169         /* check it's really written */
170         if ((temp = i2c_inb(adap)) != get_own(adap)) {
171                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
172                 return -ENXIO;
173         }
174
175         /* S1=0xA0, next byte in S2 */
176         set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
177         /* check to see S2 now selected */
178         if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
179                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
180                 return -ENXIO;
181         }
182
183         /* load clock register S2 */
184         i2c_outb(adap, get_clock(adap));
185         /* check it's really written, the only 5 lowest bits does matter */
186         if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
187                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
188                 return -ENXIO;
189         }
190
191         /* Enable serial interface, idle, S0 selected */
192         set_pcf(adap, 1, I2C_PCF_IDLE);
193
194         /* check to see PCF is really idled and we can access status register */
195         if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
196                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
197                 return -ENXIO;
198         }
199
200         printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
201
202         return 0;
203 }
204
205 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
206                          int count, int last)
207 {
208         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
209         int wrcount, status, timeout;
210
211         for (wrcount=0; wrcount<count; ++wrcount) {
212                 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
213                                 buf[wrcount] & 0xff));
214                 i2c_outb(adap, buf[wrcount]);
215                 timeout = wait_for_pin(adap, &status);
216                 if (timeout) {
217                         if (timeout == -EINTR)
218                                 return -EINTR; /* arbitration lost */
219
220                         i2c_stop(adap);
221                         dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
222                         return -EREMOTEIO; /* got a better one ?? */
223                 }
224                 if (status & I2C_PCF_LRB) {
225                         i2c_stop(adap);
226                         dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
227                         return -EREMOTEIO; /* got a better one ?? */
228                 }
229         }
230         if (last)
231                 i2c_stop(adap);
232         else
233                 i2c_repstart(adap);
234
235         return wrcount;
236 }
237
238 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
239                          int count, int last)
240 {
241         int i, status;
242         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
243         int wfp;
244
245         /* increment number of bytes to read by one -- read dummy byte */
246         for (i = 0; i <= count; i++) {
247
248                 if ((wfp = wait_for_pin(adap, &status))) {
249                         if (wfp == -EINTR)
250                                 return -EINTR; /* arbitration lost */
251
252                         i2c_stop(adap);
253                         dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
254                         return -1;
255                 }
256
257                 if ((status & I2C_PCF_LRB) && (i != count)) {
258                         i2c_stop(adap);
259                         dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
260                         return -1;
261                 }
262
263                 if (i == count - 1) {
264                         set_pcf(adap, 1, I2C_PCF_ESO);
265                 } else if (i == count) {
266                         if (last)
267                                 i2c_stop(adap);
268                         else
269                                 i2c_repstart(adap);
270                 }
271
272                 if (i)
273                         buf[i - 1] = i2c_inb(adap);
274                 else
275                         i2c_inb(adap); /* dummy read */
276         }
277
278         return i - 1;
279 }
280
281
282 static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
283                          struct i2c_msg *msg)
284 {
285         unsigned char addr = i2c_8bit_addr_from_msg(msg);
286
287         if (msg->flags & I2C_M_REV_DIR_ADDR)
288                 addr ^= 1;
289         i2c_outb(adap, addr);
290
291         return 0;
292 }
293
294 static int pcf_xfer(struct i2c_adapter *i2c_adap,
295                     struct i2c_msg *msgs,
296                     int num)
297 {
298         struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
299         struct i2c_msg *pmsg;
300         int i;
301         int ret=0, timeout, status;
302
303         if (adap->xfer_begin)
304                 adap->xfer_begin(adap->data);
305
306         /* Check for bus busy */
307         timeout = wait_for_bb(adap);
308         if (timeout) {
309                 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
310                             "Timeout waiting for BB in pcf_xfer\n");)
311                 i = -EIO;
312                 goto out;
313         }
314
315         for (i = 0;ret >= 0 && i < num; i++) {
316                 pmsg = &msgs[i];
317
318                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
319                      pmsg->flags & I2C_M_RD ? "read" : "write",
320                      pmsg->len, pmsg->addr, i + 1, num);)
321
322                 ret = pcf_doAddress(adap, pmsg);
323
324                 /* Send START */
325                 if (i == 0)
326                         i2c_start(adap);
327
328                 /* Wait for PIN (pending interrupt NOT) */
329                 timeout = wait_for_pin(adap, &status);
330                 if (timeout) {
331                         if (timeout == -EINTR) {
332                                 /* arbitration lost */
333                                 i = -EINTR;
334                                 goto out;
335                         }
336                         i2c_stop(adap);
337                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
338                                     "for PIN(1) in pcf_xfer\n");)
339                         i = -EREMOTEIO;
340                         goto out;
341                 }
342
343                 /* Check LRB (last rcvd bit - slave ack) */
344                 if (status & I2C_PCF_LRB) {
345                         i2c_stop(adap);
346                         DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
347                         i = -EREMOTEIO;
348                         goto out;
349                 }
350
351                 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
352                             i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
353
354                 if (pmsg->flags & I2C_M_RD) {
355                         ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
356                                             (i + 1 == num));
357
358                         if (ret != pmsg->len) {
359                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
360                                             "only read %d bytes.\n",ret));
361                         } else {
362                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
363                         }
364                 } else {
365                         ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
366                                             (i + 1 == num));
367
368                         if (ret != pmsg->len) {
369                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
370                                             "only wrote %d bytes.\n",ret));
371                         } else {
372                                 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
373                         }
374                 }
375         }
376
377 out:
378         if (adap->xfer_end)
379                 adap->xfer_end(adap->data);
380         return i;
381 }
382
383 static u32 pcf_func(struct i2c_adapter *adap)
384 {
385         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
386                I2C_FUNC_PROTOCOL_MANGLING;
387 }
388
389 /* exported algorithm data: */
390 static const struct i2c_algorithm pcf_algo = {
391         .master_xfer    = pcf_xfer,
392         .functionality  = pcf_func,
393 };
394
395 /*
396  * registering functions to load algorithms at runtime
397  */
398 int i2c_pcf_add_bus(struct i2c_adapter *adap)
399 {
400         struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
401         int rval;
402
403         DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
404
405         /* register new adapter to i2c module... */
406         adap->algo = &pcf_algo;
407
408         if ((rval = pcf_init_8584(pcf_adap)))
409                 return rval;
410
411         rval = i2c_add_adapter(adap);
412
413         return rval;
414 }
415 EXPORT_SYMBOL(i2c_pcf_add_bus);
416
417 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
418 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
419 MODULE_LICENSE("GPL");
420
421 module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
422 MODULE_PARM_DESC(i2c_debug,
423         "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");