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