1/*
2 *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
3 *    Copyright (C) 2004 Arcom Control Systems
4 *    Copyright (C) 2008 Pengutronix
5 *
6 *  This program is free software; you can redistribute it and/or modify
7 *  it under the terms of the GNU General Public License as published by
8 *  the Free Software Foundation; either version 2 of the License, or
9 *  (at your option) any later version.
10 *
11 *  This program is distributed in the hope that it will be useful,
12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 *  GNU General Public License for more details.
15 */
16
17#include <linux/kernel.h>
18#include <linux/module.h>
19#include <linux/moduleparam.h>
20#include <linux/delay.h>
21#include <linux/jiffies.h>
22#include <linux/errno.h>
23#include <linux/i2c.h>
24#include <linux/i2c-algo-pca.h>
25
26#define DEB1(fmt, args...) do { if (i2c_debug >= 1)			\
27				 printk(KERN_DEBUG fmt, ## args); } while (0)
28#define DEB2(fmt, args...) do { if (i2c_debug >= 2)			\
29				 printk(KERN_DEBUG fmt, ## args); } while (0)
30#define DEB3(fmt, args...) do { if (i2c_debug >= 3)			\
31				 printk(KERN_DEBUG fmt, ## args); } while (0)
32
33static int i2c_debug;
34
35#define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
36#define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
37
38#define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
39#define pca_clock(adap) adap->i2c_clock
40#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
41#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
42#define pca_wait(adap) adap->wait_for_completion(adap->data)
43
44static void pca_reset(struct i2c_algo_pca_data *adap)
45{
46	if (adap->chip == I2C_PCA_CHIP_9665) {
47		/* Ignore the reset function from the module,
48		 * we can use the parallel bus reset.
49		 */
50		pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
51		pca_outw(adap, I2C_PCA_IND, 0xA5);
52		pca_outw(adap, I2C_PCA_IND, 0x5A);
53	} else {
54		adap->reset_chip(adap->data);
55	}
56}
57
58/*
59 * Generate a start condition on the i2c bus.
60 *
61 * returns after the start condition has occurred
62 */
63static int pca_start(struct i2c_algo_pca_data *adap)
64{
65	int sta = pca_get_con(adap);
66	DEB2("=== START\n");
67	sta |= I2C_PCA_CON_STA;
68	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
69	pca_set_con(adap, sta);
70	return pca_wait(adap);
71}
72
73/*
74 * Generate a repeated start condition on the i2c bus
75 *
76 * return after the repeated start condition has occurred
77 */
78static int pca_repeated_start(struct i2c_algo_pca_data *adap)
79{
80	int sta = pca_get_con(adap);
81	DEB2("=== REPEATED START\n");
82	sta |= I2C_PCA_CON_STA;
83	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
84	pca_set_con(adap, sta);
85	return pca_wait(adap);
86}
87
88/*
89 * Generate a stop condition on the i2c bus
90 *
91 * returns after the stop condition has been generated
92 *
93 * STOPs do not generate an interrupt or set the SI flag, since the
94 * part returns the idle state (0xf8). Hence we don't need to
95 * pca_wait here.
96 */
97static void pca_stop(struct i2c_algo_pca_data *adap)
98{
99	int sta = pca_get_con(adap);
100	DEB2("=== STOP\n");
101	sta |= I2C_PCA_CON_STO;
102	sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
103	pca_set_con(adap, sta);
104}
105
106/*
107 * Send the slave address and R/W bit
108 *
109 * returns after the address has been sent
110 */
111static int pca_address(struct i2c_algo_pca_data *adap,
112		       struct i2c_msg *msg)
113{
114	int sta = pca_get_con(adap);
115	int addr;
116
117	addr = ((0x7f & msg->addr) << 1);
118	if (msg->flags & I2C_M_RD)
119		addr |= 1;
120	DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
121	     msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
122
123	pca_outw(adap, I2C_PCA_DAT, addr);
124
125	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
126	pca_set_con(adap, sta);
127
128	return pca_wait(adap);
129}
130
131/*
132 * Transmit a byte.
133 *
134 * Returns after the byte has been transmitted
135 */
136static int pca_tx_byte(struct i2c_algo_pca_data *adap,
137		       __u8 b)
138{
139	int sta = pca_get_con(adap);
140	DEB2("=== WRITE %#04x\n", b);
141	pca_outw(adap, I2C_PCA_DAT, b);
142
143	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
144	pca_set_con(adap, sta);
145
146	return pca_wait(adap);
147}
148
149/*
150 * Receive a byte
151 *
152 * returns immediately.
153 */
154static void pca_rx_byte(struct i2c_algo_pca_data *adap,
155			__u8 *b, int ack)
156{
157	*b = pca_inw(adap, I2C_PCA_DAT);
158	DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
159}
160
161/*
162 * Setup ACK or NACK for next received byte and wait for it to arrive.
163 *
164 * Returns after next byte has arrived.
165 */
166static int pca_rx_ack(struct i2c_algo_pca_data *adap,
167		      int ack)
168{
169	int sta = pca_get_con(adap);
170
171	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
172
173	if (ack)
174		sta |= I2C_PCA_CON_AA;
175
176	pca_set_con(adap, sta);
177	return pca_wait(adap);
178}
179
180static int pca_xfer(struct i2c_adapter *i2c_adap,
181		    struct i2c_msg *msgs,
182		    int num)
183{
184	struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
185	struct i2c_msg *msg = NULL;
186	int curmsg;
187	int numbytes = 0;
188	int state;
189	int ret;
190	int completed = 1;
191	unsigned long timeout = jiffies + i2c_adap->timeout;
192
193	while ((state = pca_status(adap)) != 0xf8) {
194		if (time_before(jiffies, timeout)) {
195			msleep(10);
196		} else {
197			dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
198				"%#04x\n", state);
199			return -EBUSY;
200		}
201	}
202
203	DEB1("{{{ XFER %d messages\n", num);
204
205	if (i2c_debug >= 2) {
206		for (curmsg = 0; curmsg < num; curmsg++) {
207			int addr, i;
208			msg = &msgs[curmsg];
209
210			addr = (0x7f & msg->addr) ;
211
212			if (msg->flags & I2C_M_RD)
213				printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
214				       curmsg, msg->len, addr, (addr << 1) | 1);
215			else {
216				printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
217				       curmsg, msg->len, addr, addr << 1,
218				       msg->len == 0 ? "" : ", ");
219				for (i = 0; i < msg->len; i++)
220					printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
221				printk("]\n");
222			}
223		}
224	}
225
226	curmsg = 0;
227	ret = -EIO;
228	while (curmsg < num) {
229		state = pca_status(adap);
230
231		DEB3("STATE is 0x%02x\n", state);
232		msg = &msgs[curmsg];
233
234		switch (state) {
235		case 0xf8: /* On reset or stop the bus is idle */
236			completed = pca_start(adap);
237			break;
238
239		case 0x08: /* A START condition has been transmitted */
240		case 0x10: /* A repeated start condition has been transmitted */
241			completed = pca_address(adap, msg);
242			break;
243
244		case 0x18: /* SLA+W has been transmitted; ACK has been received */
245		case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
246			if (numbytes < msg->len) {
247				completed = pca_tx_byte(adap,
248							msg->buf[numbytes]);
249				numbytes++;
250				break;
251			}
252			curmsg++; numbytes = 0;
253			if (curmsg == num)
254				pca_stop(adap);
255			else
256				completed = pca_repeated_start(adap);
257			break;
258
259		case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
260			DEB2("NOT ACK received after SLA+W\n");
261			pca_stop(adap);
262			ret = -ENXIO;
263			goto out;
264
265		case 0x40: /* SLA+R has been transmitted; ACK has been received */
266			completed = pca_rx_ack(adap, msg->len > 1);
267			break;
268
269		case 0x50: /* Data bytes has been received; ACK has been returned */
270			if (numbytes < msg->len) {
271				pca_rx_byte(adap, &msg->buf[numbytes], 1);
272				numbytes++;
273				completed = pca_rx_ack(adap,
274						       numbytes < msg->len - 1);
275				break;
276			}
277			curmsg++; numbytes = 0;
278			if (curmsg == num)
279				pca_stop(adap);
280			else
281				completed = pca_repeated_start(adap);
282			break;
283
284		case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
285			DEB2("NOT ACK received after SLA+R\n");
286			pca_stop(adap);
287			ret = -ENXIO;
288			goto out;
289
290		case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
291			DEB2("NOT ACK received after data byte\n");
292			pca_stop(adap);
293			goto out;
294
295		case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
296			DEB2("Arbitration lost\n");
297			/*
298			 * The PCA9564 data sheet (2006-09-01) says "A
299			 * START condition will be transmitted when the
300			 * bus becomes free (STOP or SCL and SDA high)"
301			 * when the STA bit is set (p. 11).
302			 *
303			 * In case this won't work, try pca_reset()
304			 * instead.
305			 */
306			pca_start(adap);
307			goto out;
308
309		case 0x58: /* Data byte has been received; NOT ACK has been returned */
310			if (numbytes == msg->len - 1) {
311				pca_rx_byte(adap, &msg->buf[numbytes], 0);
312				curmsg++; numbytes = 0;
313				if (curmsg == num)
314					pca_stop(adap);
315				else
316					completed = pca_repeated_start(adap);
317			} else {
318				DEB2("NOT ACK sent after data byte received. "
319				     "Not final byte. numbytes %d. len %d\n",
320				     numbytes, msg->len);
321				pca_stop(adap);
322				goto out;
323			}
324			break;
325		case 0x70: /* Bus error - SDA stuck low */
326			DEB2("BUS ERROR - SDA Stuck low\n");
327			pca_reset(adap);
328			goto out;
329		case 0x90: /* Bus error - SCL stuck low */
330			DEB2("BUS ERROR - SCL Stuck low\n");
331			pca_reset(adap);
332			goto out;
333		case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
334			DEB2("BUS ERROR - Illegal START or STOP\n");
335			pca_reset(adap);
336			goto out;
337		default:
338			dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
339			break;
340		}
341
342		if (!completed)
343			goto out;
344	}
345
346	ret = curmsg;
347 out:
348	DEB1("}}} transferred %d/%d messages. "
349	     "status is %#04x. control is %#04x\n",
350	     curmsg, num, pca_status(adap),
351	     pca_get_con(adap));
352	return ret;
353}
354
355static u32 pca_func(struct i2c_adapter *adap)
356{
357	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
358}
359
360static const struct i2c_algorithm pca_algo = {
361	.master_xfer	= pca_xfer,
362	.functionality	= pca_func,
363};
364
365static unsigned int pca_probe_chip(struct i2c_adapter *adap)
366{
367	struct i2c_algo_pca_data *pca_data = adap->algo_data;
368	/* The trick here is to check if there is an indirect register
369	 * available. If there is one, we will read the value we first
370	 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
371	 * we wrote on I2C_PCA_ADR
372	 */
373	pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
374	pca_outw(pca_data, I2C_PCA_IND, 0xAA);
375	pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
376	pca_outw(pca_data, I2C_PCA_IND, 0x00);
377	pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
378	if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
379		printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
380		pca_data->chip = I2C_PCA_CHIP_9665;
381	} else {
382		printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
383		pca_data->chip = I2C_PCA_CHIP_9564;
384	}
385	return pca_data->chip;
386}
387
388static int pca_init(struct i2c_adapter *adap)
389{
390	struct i2c_algo_pca_data *pca_data = adap->algo_data;
391
392	adap->algo = &pca_algo;
393
394	if (pca_probe_chip(adap) == I2C_PCA_CHIP_9564) {
395		static int freqs[] = {330, 288, 217, 146, 88, 59, 44, 36};
396		int clock;
397
398		if (pca_data->i2c_clock > 7) {
399			switch (pca_data->i2c_clock) {
400			case 330000:
401				pca_data->i2c_clock = I2C_PCA_CON_330kHz;
402				break;
403			case 288000:
404				pca_data->i2c_clock = I2C_PCA_CON_288kHz;
405				break;
406			case 217000:
407				pca_data->i2c_clock = I2C_PCA_CON_217kHz;
408				break;
409			case 146000:
410				pca_data->i2c_clock = I2C_PCA_CON_146kHz;
411				break;
412			case 88000:
413				pca_data->i2c_clock = I2C_PCA_CON_88kHz;
414				break;
415			case 59000:
416				pca_data->i2c_clock = I2C_PCA_CON_59kHz;
417				break;
418			case 44000:
419				pca_data->i2c_clock = I2C_PCA_CON_44kHz;
420				break;
421			case 36000:
422				pca_data->i2c_clock = I2C_PCA_CON_36kHz;
423				break;
424			default:
425				printk(KERN_WARNING
426					"%s: Invalid I2C clock speed selected."
427					" Using default 59kHz.\n", adap->name);
428			pca_data->i2c_clock = I2C_PCA_CON_59kHz;
429			}
430		} else {
431			printk(KERN_WARNING "%s: "
432				"Choosing the clock frequency based on "
433				"index is deprecated."
434				" Use the nominal frequency.\n", adap->name);
435		}
436
437		pca_reset(pca_data);
438
439		clock = pca_clock(pca_data);
440		printk(KERN_INFO "%s: Clock frequency is %dkHz\n",
441		     adap->name, freqs[clock]);
442
443		pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock);
444	} else {
445		int clock;
446		int mode;
447		int tlow, thi;
448		/* Values can be found on PCA9665 datasheet section 7.3.2.6 */
449		int min_tlow, min_thi;
450		/* These values are the maximum raise and fall values allowed
451		 * by the I2C operation mode (Standard, Fast or Fast+)
452		 * They are used (added) below to calculate the clock dividers
453		 * of PCA9665. Note that they are slightly different of the
454		 * real maximum, to allow the change on mode exactly on the
455		 * maximum clock rate for each mode
456		 */
457		int raise_fall_time;
458
459		if (pca_data->i2c_clock > 1265800) {
460			printk(KERN_WARNING "%s: I2C clock speed too high."
461				" Using 1265.8kHz.\n", adap->name);
462			pca_data->i2c_clock = 1265800;
463		}
464
465		if (pca_data->i2c_clock < 60300) {
466			printk(KERN_WARNING "%s: I2C clock speed too low."
467				" Using 60.3kHz.\n", adap->name);
468			pca_data->i2c_clock = 60300;
469		}
470
471		/* To avoid integer overflow, use clock/100 for calculations */
472		clock = pca_clock(pca_data) / 100;
473
474		if (pca_data->i2c_clock > 1000000) {
475			mode = I2C_PCA_MODE_TURBO;
476			min_tlow = 14;
477			min_thi  = 5;
478			raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
479		} else if (pca_data->i2c_clock > 400000) {
480			mode = I2C_PCA_MODE_FASTP;
481			min_tlow = 17;
482			min_thi  = 9;
483			raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
484		} else if (pca_data->i2c_clock > 100000) {
485			mode = I2C_PCA_MODE_FAST;
486			min_tlow = 44;
487			min_thi  = 20;
488			raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
489		} else {
490			mode = I2C_PCA_MODE_STD;
491			min_tlow = 157;
492			min_thi  = 134;
493			raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
494		}
495
496		/* The minimum clock that respects the thi/tlow = 134/157 is
497		 * 64800 Hz. Below that, we have to fix the tlow to 255 and
498		 * calculate the thi factor.
499		 */
500		if (clock < 648) {
501			tlow = 255;
502			thi = 1000000 - clock * raise_fall_time;
503			thi /= (I2C_PCA_OSC_PER * clock) - tlow;
504		} else {
505			tlow = (1000000 - clock * raise_fall_time) * min_tlow;
506			tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
507			thi = tlow * min_thi / min_tlow;
508		}
509
510		pca_reset(pca_data);
511
512		printk(KERN_INFO
513		     "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
514
515		pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
516		pca_outw(pca_data, I2C_PCA_IND, mode);
517		pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
518		pca_outw(pca_data, I2C_PCA_IND, tlow);
519		pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
520		pca_outw(pca_data, I2C_PCA_IND, thi);
521
522		pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
523	}
524	udelay(500); /* 500 us for oscilator to stabilise */
525
526	return 0;
527}
528
529/*
530 * registering functions to load algorithms at runtime
531 */
532int i2c_pca_add_bus(struct i2c_adapter *adap)
533{
534	int rval;
535
536	rval = pca_init(adap);
537	if (rval)
538		return rval;
539
540	return i2c_add_adapter(adap);
541}
542EXPORT_SYMBOL(i2c_pca_add_bus);
543
544int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
545{
546	int rval;
547
548	rval = pca_init(adap);
549	if (rval)
550		return rval;
551
552	return i2c_add_numbered_adapter(adap);
553}
554EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
555
556MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
557	"Wolfram Sang <w.sang@pengutronix.de>");
558MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
559MODULE_LICENSE("GPL");
560
561module_param(i2c_debug, int, 0);
562