1/*
2 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
3 *
4 *   Copyright (C) 1995-1997 Simon G. Vogl
5 *		   1998-2000 Hans Berglund
6 *
7 *  This program is free software; you can redistribute it and/or modify
8 *  it under the terms of the GNU General Public License as published by
9 *  the Free Software Foundation; either version 2 of the License, or
10 *  (at your option) any later version.
11 *
12 *  This program is distributed in the hope that it will be useful,
13 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
14 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 *  GNU General Public License for more details.
16 *
17 *  You should have received a copy of the GNU General Public License
18 *  along with this program; if not, write to the Free Software
19 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
20 *  MA 02110-1301 USA.
21 *
22 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
23 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
24 * <mbailey@littlefeet-inc.com>
25 *
26 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
27 * messages, proper stop/repstart signaling during receive, added detect code
28 */
29
30#include <linux/kernel.h>
31#include <linux/module.h>
32#include <linux/delay.h>
33#include <linux/init.h>
34#include <linux/errno.h>
35#include <linux/i2c.h>
36#include <linux/i2c-algo-pcf.h>
37#include "i2c-algo-pcf.h"
38
39
40#define DEB2(x) if (i2c_debug >= 2) x
41#define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */
42#define DEBPROTO(x) if (i2c_debug >= 9) x;
43	/* debug the protocol by showing transferred bits */
44#define DEF_TIMEOUT 16
45
46/*
47 * module parameters:
48 */
49static int i2c_debug;
50
51/* setting states on the bus with the right timing: */
52
53#define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
54#define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
55#define get_own(adap) adap->getown(adap->data)
56#define get_clock(adap) adap->getclock(adap->data)
57#define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
58#define i2c_inb(adap) adap->getpcf(adap->data, 0)
59
60/* other auxiliary functions */
61
62static void i2c_start(struct i2c_algo_pcf_data *adap)
63{
64	DEBPROTO(printk(KERN_DEBUG "S "));
65	set_pcf(adap, 1, I2C_PCF_START);
66}
67
68static void i2c_repstart(struct i2c_algo_pcf_data *adap)
69{
70	DEBPROTO(printk(" Sr "));
71	set_pcf(adap, 1, I2C_PCF_REPSTART);
72}
73
74static void i2c_stop(struct i2c_algo_pcf_data *adap)
75{
76	DEBPROTO(printk("P\n"));
77	set_pcf(adap, 1, I2C_PCF_STOP);
78}
79
80static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
81{
82	DEB2(printk(KERN_INFO
83		"i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n",
84		*status));
85	/*
86	 * Cleanup from LAB -- reset and enable ESO.
87	 * This resets the PCF8584; since we've lost the bus, no
88	 * further attempts should be made by callers to clean up
89	 * (no i2c_stop() etc.)
90	 */
91	set_pcf(adap, 1, I2C_PCF_PIN);
92	set_pcf(adap, 1, I2C_PCF_ESO);
93	/*
94	 * We pause for a time period sufficient for any running
95	 * I2C transaction to complete -- the arbitration logic won't
96	 * work properly until the next START is seen.
97	 * It is assumed the bus driver or client has set a proper value.
98	 *
99	 * REVISIT: should probably use msleep instead of mdelay if we
100	 * know we can sleep.
101	 */
102	if (adap->lab_mdelay)
103		mdelay(adap->lab_mdelay);
104
105	DEB2(printk(KERN_INFO
106		"i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n",
107		get_pcf(adap, 1)));
108}
109
110static int wait_for_bb(struct i2c_algo_pcf_data *adap)
111{
112
113	int timeout = DEF_TIMEOUT;
114	int status;
115
116	status = get_pcf(adap, 1);
117
118	while (!(status & I2C_PCF_BB) && --timeout) {
119		udelay(100); /* wait for 100 us */
120		status = get_pcf(adap, 1);
121	}
122
123	if (timeout == 0) {
124		printk(KERN_ERR "Timeout waiting for Bus Busy\n");
125		return -ETIMEDOUT;
126	}
127
128	return 0;
129}
130
131static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
132{
133
134	int timeout = DEF_TIMEOUT;
135
136	*status = get_pcf(adap, 1);
137
138	while ((*status & I2C_PCF_PIN) && --timeout) {
139		adap->waitforpin(adap->data);
140		*status = get_pcf(adap, 1);
141	}
142	if (*status & I2C_PCF_LAB) {
143		handle_lab(adap, status);
144		return -EINTR;
145	}
146
147	if (timeout == 0)
148		return -ETIMEDOUT;
149
150	return 0;
151}
152
153/*
154 * This should perform the 'PCF8584 initialization sequence' as described
155 * in the Philips IC12 data book (1995, Aug 29).
156 * There should be a 30 clock cycle wait after reset, I assume this
157 * has been fulfilled.
158 * There should be a delay at the end equal to the longest I2C message
159 * to synchronize the BB-bit (in multimaster systems). How long is
160 * this? I assume 1 second is always long enough.
161 *
162 * vdovikin: added detect code for PCF8584
163 */
164static int pcf_init_8584 (struct i2c_algo_pcf_data *adap)
165{
166	unsigned char temp;
167
168	DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n",
169				get_pcf(adap, 1)));
170
171	/* S1=0x80: S0 selected, serial interface off */
172	set_pcf(adap, 1, I2C_PCF_PIN);
173	/*
174	 * check to see S1 now used as R/W ctrl -
175	 * PCF8584 does that when ESO is zero
176	 */
177	if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) {
178		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp));
179		return -ENXIO; /* definitely not PCF8584 */
180	}
181
182	/* load own address in S0, effective address is (own << 1) */
183	i2c_outb(adap, get_own(adap));
184	/* check it's really written */
185	if ((temp = i2c_inb(adap)) != get_own(adap)) {
186		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp));
187		return -ENXIO;
188	}
189
190	/* S1=0xA0, next byte in S2 */
191	set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
192	/* check to see S2 now selected */
193	if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) {
194		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp));
195		return -ENXIO;
196	}
197
198	/* load clock register S2 */
199	i2c_outb(adap, get_clock(adap));
200	/* check it's really written, the only 5 lowest bits does matter */
201	if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) {
202		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp));
203		return -ENXIO;
204	}
205
206	/* Enable serial interface, idle, S0 selected */
207	set_pcf(adap, 1, I2C_PCF_IDLE);
208
209	/* check to see PCF is really idled and we can access status register */
210	if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) {
211		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp));
212		return -ENXIO;
213	}
214
215	printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
216
217	return 0;
218}
219
220static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
221			 int count, int last)
222{
223	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
224	int wrcount, status, timeout;
225
226	for (wrcount=0; wrcount<count; ++wrcount) {
227		DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n",
228				buf[wrcount] & 0xff));
229		i2c_outb(adap, buf[wrcount]);
230		timeout = wait_for_pin(adap, &status);
231		if (timeout) {
232			if (timeout == -EINTR)
233				return -EINTR; /* arbitration lost */
234
235			i2c_stop(adap);
236			dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
237			return -EREMOTEIO; /* got a better one ?? */
238		}
239		if (status & I2C_PCF_LRB) {
240			i2c_stop(adap);
241			dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
242			return -EREMOTEIO; /* got a better one ?? */
243		}
244	}
245	if (last)
246		i2c_stop(adap);
247	else
248		i2c_repstart(adap);
249
250	return wrcount;
251}
252
253static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
254			 int count, int last)
255{
256	int i, status;
257	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
258	int wfp;
259
260	/* increment number of bytes to read by one -- read dummy byte */
261	for (i = 0; i <= count; i++) {
262
263		if ((wfp = wait_for_pin(adap, &status))) {
264			if (wfp == -EINTR)
265				return -EINTR; /* arbitration lost */
266
267			i2c_stop(adap);
268			dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
269			return -1;
270		}
271
272		if ((status & I2C_PCF_LRB) && (i != count)) {
273			i2c_stop(adap);
274			dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
275			return -1;
276		}
277
278		if (i == count - 1) {
279			set_pcf(adap, 1, I2C_PCF_ESO);
280		} else if (i == count) {
281			if (last)
282				i2c_stop(adap);
283			else
284				i2c_repstart(adap);
285		}
286
287		if (i)
288			buf[i - 1] = i2c_inb(adap);
289		else
290			i2c_inb(adap); /* dummy read */
291	}
292
293	return i - 1;
294}
295
296
297static int pcf_doAddress(struct i2c_algo_pcf_data *adap,
298			 struct i2c_msg *msg)
299{
300	unsigned short flags = msg->flags;
301	unsigned char addr;
302
303	addr = msg->addr << 1;
304	if (flags & I2C_M_RD)
305		addr |= 1;
306	if (flags & I2C_M_REV_DIR_ADDR)
307		addr ^= 1;
308	i2c_outb(adap, addr);
309
310	return 0;
311}
312
313static int pcf_xfer(struct i2c_adapter *i2c_adap,
314		    struct i2c_msg *msgs,
315		    int num)
316{
317	struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
318	struct i2c_msg *pmsg;
319	int i;
320	int ret=0, timeout, status;
321
322	if (adap->xfer_begin)
323		adap->xfer_begin(adap->data);
324
325	/* Check for bus busy */
326	timeout = wait_for_bb(adap);
327	if (timeout) {
328		DEB2(printk(KERN_ERR "i2c-algo-pcf.o: "
329			    "Timeout waiting for BB in pcf_xfer\n");)
330		i = -EIO;
331		goto out;
332	}
333
334	for (i = 0;ret >= 0 && i < num; i++) {
335		pmsg = &msgs[i];
336
337		DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n",
338		     pmsg->flags & I2C_M_RD ? "read" : "write",
339		     pmsg->len, pmsg->addr, i + 1, num);)
340
341		ret = pcf_doAddress(adap, pmsg);
342
343		/* Send START */
344		if (i == 0)
345			i2c_start(adap);
346
347		/* Wait for PIN (pending interrupt NOT) */
348		timeout = wait_for_pin(adap, &status);
349		if (timeout) {
350			if (timeout == -EINTR) {
351				/* arbitration lost */
352				i = -EINTR;
353				goto out;
354			}
355			i2c_stop(adap);
356			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting "
357				    "for PIN(1) in pcf_xfer\n");)
358			i = -EREMOTEIO;
359			goto out;
360		}
361
362		/* Check LRB (last rcvd bit - slave ack) */
363		if (status & I2C_PCF_LRB) {
364			i2c_stop(adap);
365			DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");)
366			i = -EREMOTEIO;
367			goto out;
368		}
369
370		DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n",
371			    i, msgs[i].addr, msgs[i].flags, msgs[i].len);)
372
373		if (pmsg->flags & I2C_M_RD) {
374			ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
375					    (i + 1 == num));
376
377			if (ret != pmsg->len) {
378				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
379					    "only read %d bytes.\n",ret));
380			} else {
381				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret));
382			}
383		} else {
384			ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
385					    (i + 1 == num));
386
387			if (ret != pmsg->len) {
388				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: "
389					    "only wrote %d bytes.\n",ret));
390			} else {
391				DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret));
392			}
393		}
394	}
395
396out:
397	if (adap->xfer_end)
398		adap->xfer_end(adap->data);
399	return i;
400}
401
402static u32 pcf_func(struct i2c_adapter *adap)
403{
404	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
405	       I2C_FUNC_PROTOCOL_MANGLING;
406}
407
408/* exported algorithm data: */
409static const struct i2c_algorithm pcf_algo = {
410	.master_xfer	= pcf_xfer,
411	.functionality	= pcf_func,
412};
413
414/*
415 * registering functions to load algorithms at runtime
416 */
417int i2c_pcf_add_bus(struct i2c_adapter *adap)
418{
419	struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
420	int rval;
421
422	DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
423
424	/* register new adapter to i2c module... */
425	adap->algo = &pcf_algo;
426
427	if ((rval = pcf_init_8584(pcf_adap)))
428		return rval;
429
430	rval = i2c_add_adapter(adap);
431
432	return rval;
433}
434EXPORT_SYMBOL(i2c_pcf_add_bus);
435
436MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
437MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
438MODULE_LICENSE("GPL");
439
440module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
441MODULE_PARM_DESC(i2c_debug,
442	"debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol");
443