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 
i2c_start(struct i2c_algo_pcf_data * adap)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 
i2c_repstart(struct i2c_algo_pcf_data * adap)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 
i2c_stop(struct i2c_algo_pcf_data * adap)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 
handle_lab(struct i2c_algo_pcf_data * adap,const int * status)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 
wait_for_bb(struct i2c_algo_pcf_data * adap)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 
wait_for_pin(struct i2c_algo_pcf_data * adap,int * status)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  */
pcf_init_8584(struct i2c_algo_pcf_data * adap)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 
pcf_sendbytes(struct i2c_adapter * i2c_adap,const char * buf,int count,int last)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 
pcf_readbytes(struct i2c_adapter * i2c_adap,char * buf,int count,int last)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 
pcf_doAddress(struct i2c_algo_pcf_data * adap,struct i2c_msg * msg)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 
pcf_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)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 
pcf_func(struct i2c_adapter * adap)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  */
i2c_pcf_add_bus(struct i2c_adapter * adap)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");
424