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 Ky��sti M��lkki <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 */
34static 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
47static 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
53static void i2c_repstart(struct i2c_algo_pcf_data *adap)
54{
55	DEBPROTO(printk(" Sr "));
56	set_pcf(adap, 1, I2C_PCF_REPSTART);
57}
58
59static 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
65static 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
95static 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
116static 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 */
149static 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
205static 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
238static 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
282static 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
294static 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
377out:
378	if (adap->xfer_end)
379		adap->xfer_end(adap->data);
380	return i;
381}
382
383static 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: */
390static 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 */
398int 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}
415EXPORT_SYMBOL(i2c_pcf_add_bus);
416
417MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
418MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
419MODULE_LICENSE("GPL");
420
421module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
422MODULE_PARM_DESC(i2c_debug,
423	"debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
424