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 *  You should have received a copy of the GNU General Public License
17 *  along with this program; if not, write to the Free Software
18 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
19 *  MA 02110-1301 USA.
20 */
21
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/moduleparam.h>
25#include <linux/delay.h>
26#include <linux/jiffies.h>
27#include <linux/init.h>
28#include <linux/errno.h>
29#include <linux/i2c.h>
30#include <linux/i2c-algo-pca.h>
31
32#define DEB1(fmt, args...) do { if (i2c_debug >= 1)			\
33				 printk(KERN_DEBUG fmt, ## args); } while (0)
34#define DEB2(fmt, args...) do { if (i2c_debug >= 2)			\
35				 printk(KERN_DEBUG fmt, ## args); } while (0)
36#define DEB3(fmt, args...) do { if (i2c_debug >= 3)			\
37				 printk(KERN_DEBUG fmt, ## args); } while (0)
38
39static int i2c_debug;
40
41#define pca_outw(adap, reg, val) adap->write_byte(adap->data, reg, val)
42#define pca_inw(adap, reg) adap->read_byte(adap->data, reg)
43
44#define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
45#define pca_clock(adap) adap->i2c_clock
46#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
47#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
48#define pca_wait(adap) adap->wait_for_completion(adap->data)
49#define pca_reset(adap) adap->reset_chip(adap->data)
50
51static void pca9665_reset(void *pd)
52{
53	struct i2c_algo_pca_data *adap = pd;
54	pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET);
55	pca_outw(adap, I2C_PCA_IND, 0xA5);
56	pca_outw(adap, I2C_PCA_IND, 0x5A);
57}
58
59/*
60 * Generate a start condition on the i2c bus.
61 *
62 * returns after the start condition has occurred
63 */
64static int pca_start(struct i2c_algo_pca_data *adap)
65{
66	int sta = pca_get_con(adap);
67	DEB2("=== START\n");
68	sta |= I2C_PCA_CON_STA;
69	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
70	pca_set_con(adap, sta);
71	return pca_wait(adap);
72}
73
74/*
75 * Generate a repeated start condition on the i2c bus
76 *
77 * return after the repeated start condition has occurred
78 */
79static int pca_repeated_start(struct i2c_algo_pca_data *adap)
80{
81	int sta = pca_get_con(adap);
82	DEB2("=== REPEATED START\n");
83	sta |= I2C_PCA_CON_STA;
84	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
85	pca_set_con(adap, sta);
86	return pca_wait(adap);
87}
88
89/*
90 * Generate a stop condition on the i2c bus
91 *
92 * returns after the stop condition has been generated
93 *
94 * STOPs do not generate an interrupt or set the SI flag, since the
95 * part returns the idle state (0xf8). Hence we don't need to
96 * pca_wait here.
97 */
98static void pca_stop(struct i2c_algo_pca_data *adap)
99{
100	int sta = pca_get_con(adap);
101	DEB2("=== STOP\n");
102	sta |= I2C_PCA_CON_STO;
103	sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
104	pca_set_con(adap, sta);
105}
106
107/*
108 * Send the slave address and R/W bit
109 *
110 * returns after the address has been sent
111 */
112static int pca_address(struct i2c_algo_pca_data *adap,
113		       struct i2c_msg *msg)
114{
115	int sta = pca_get_con(adap);
116	int addr;
117
118	addr = ((0x7f & msg->addr) << 1);
119	if (msg->flags & I2C_M_RD)
120		addr |= 1;
121	DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
122	     msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
123
124	pca_outw(adap, I2C_PCA_DAT, addr);
125
126	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
127	pca_set_con(adap, sta);
128
129	return pca_wait(adap);
130}
131
132/*
133 * Transmit a byte.
134 *
135 * Returns after the byte has been transmitted
136 */
137static int pca_tx_byte(struct i2c_algo_pca_data *adap,
138		       __u8 b)
139{
140	int sta = pca_get_con(adap);
141	DEB2("=== WRITE %#04x\n", b);
142	pca_outw(adap, I2C_PCA_DAT, b);
143
144	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
145	pca_set_con(adap, sta);
146
147	return pca_wait(adap);
148}
149
150/*
151 * Receive a byte
152 *
153 * returns immediately.
154 */
155static void pca_rx_byte(struct i2c_algo_pca_data *adap,
156			__u8 *b, int ack)
157{
158	*b = pca_inw(adap, I2C_PCA_DAT);
159	DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
160}
161
162/*
163 * Setup ACK or NACK for next received byte and wait for it to arrive.
164 *
165 * Returns after next byte has arrived.
166 */
167static int pca_rx_ack(struct i2c_algo_pca_data *adap,
168		      int ack)
169{
170	int sta = pca_get_con(adap);
171
172	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
173
174	if (ack)
175		sta |= I2C_PCA_CON_AA;
176
177	pca_set_con(adap, sta);
178	return pca_wait(adap);
179}
180
181static int pca_xfer(struct i2c_adapter *i2c_adap,
182		    struct i2c_msg *msgs,
183		    int num)
184{
185	struct i2c_algo_pca_data *adap = i2c_adap->algo_data;
186	struct i2c_msg *msg = NULL;
187	int curmsg;
188	int numbytes = 0;
189	int state;
190	int ret;
191	int completed = 1;
192	unsigned long timeout = jiffies + i2c_adap->timeout;
193
194	while ((state = pca_status(adap)) != 0xf8) {
195		if (time_before(jiffies, timeout)) {
196			msleep(10);
197		} else {
198			dev_dbg(&i2c_adap->dev, "bus is not idle. status is "
199				"%#04x\n", state);
200			return -EBUSY;
201		}
202	}
203
204	DEB1("{{{ XFER %d messages\n", num);
205
206	if (i2c_debug >= 2) {
207		for (curmsg = 0; curmsg < num; curmsg++) {
208			int addr, i;
209			msg = &msgs[curmsg];
210
211			addr = (0x7f & msg->addr) ;
212
213			if (msg->flags & I2C_M_RD)
214				printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
215				       curmsg, msg->len, addr, (addr << 1) | 1);
216			else {
217				printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
218				       curmsg, msg->len, addr, addr << 1,
219				       msg->len == 0 ? "" : ", ");
220				for (i = 0; i < msg->len; i++)
221					printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
222				printk("]\n");
223			}
224		}
225	}
226
227	curmsg = 0;
228	ret = -EIO;
229	while (curmsg < num) {
230		state = pca_status(adap);
231
232		DEB3("STATE is 0x%02x\n", state);
233		msg = &msgs[curmsg];
234
235		switch (state) {
236		case 0xf8: /* On reset or stop the bus is idle */
237			completed = pca_start(adap);
238			break;
239
240		case 0x08: /* A START condition has been transmitted */
241		case 0x10: /* A repeated start condition has been transmitted */
242			completed = pca_address(adap, msg);
243			break;
244
245		case 0x18: /* SLA+W has been transmitted; ACK has been received */
246		case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
247			if (numbytes < msg->len) {
248				completed = pca_tx_byte(adap,
249							msg->buf[numbytes]);
250				numbytes++;
251				break;
252			}
253			curmsg++; numbytes = 0;
254			if (curmsg == num)
255				pca_stop(adap);
256			else
257				completed = pca_repeated_start(adap);
258			break;
259
260		case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
261			DEB2("NOT ACK received after SLA+W\n");
262			pca_stop(adap);
263			ret = -ENXIO;
264			goto out;
265
266		case 0x40: /* SLA+R has been transmitted; ACK has been received */
267			completed = pca_rx_ack(adap, msg->len > 1);
268			break;
269
270		case 0x50: /* Data bytes has been received; ACK has been returned */
271			if (numbytes < msg->len) {
272				pca_rx_byte(adap, &msg->buf[numbytes], 1);
273				numbytes++;
274				completed = pca_rx_ack(adap,
275						       numbytes < msg->len - 1);
276				break;
277			}
278			curmsg++; numbytes = 0;
279			if (curmsg == num)
280				pca_stop(adap);
281			else
282				completed = pca_repeated_start(adap);
283			break;
284
285		case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
286			DEB2("NOT ACK received after SLA+R\n");
287			pca_stop(adap);
288			ret = -ENXIO;
289			goto out;
290
291		case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
292			DEB2("NOT ACK received after data byte\n");
293			pca_stop(adap);
294			goto out;
295
296		case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
297			DEB2("Arbitration lost\n");
298			/*
299			 * The PCA9564 data sheet (2006-09-01) says "A
300			 * START condition will be transmitted when the
301			 * bus becomes free (STOP or SCL and SDA high)"
302			 * when the STA bit is set (p. 11).
303			 *
304			 * In case this won't work, try pca_reset()
305			 * instead.
306			 */
307			pca_start(adap);
308			goto out;
309
310		case 0x58: /* Data byte has been received; NOT ACK has been returned */
311			if (numbytes == msg->len - 1) {
312				pca_rx_byte(adap, &msg->buf[numbytes], 0);
313				curmsg++; numbytes = 0;
314				if (curmsg == num)
315					pca_stop(adap);
316				else
317					completed = pca_repeated_start(adap);
318			} else {
319				DEB2("NOT ACK sent after data byte received. "
320				     "Not final byte. numbytes %d. len %d\n",
321				     numbytes, msg->len);
322				pca_stop(adap);
323				goto out;
324			}
325			break;
326		case 0x70: /* Bus error - SDA stuck low */
327			DEB2("BUS ERROR - SDA Stuck low\n");
328			pca_reset(adap);
329			goto out;
330		case 0x90: /* Bus error - SCL stuck low */
331			DEB2("BUS ERROR - SCL Stuck low\n");
332			pca_reset(adap);
333			goto out;
334		case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
335			DEB2("BUS ERROR - Illegal START or STOP\n");
336			pca_reset(adap);
337			goto out;
338		default:
339			dev_err(&i2c_adap->dev, "unhandled SIO state 0x%02x\n", state);
340			break;
341		}
342
343		if (!completed)
344			goto out;
345	}
346
347	ret = curmsg;
348 out:
349	DEB1("}}} transferred %d/%d messages. "
350	     "status is %#04x. control is %#04x\n",
351	     curmsg, num, pca_status(adap),
352	     pca_get_con(adap));
353	return ret;
354}
355
356static u32 pca_func(struct i2c_adapter *adap)
357{
358	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
359}
360
361static const struct i2c_algorithm pca_algo = {
362	.master_xfer	= pca_xfer,
363	.functionality	= pca_func,
364};
365
366static unsigned int pca_probe_chip(struct i2c_adapter *adap)
367{
368	struct i2c_algo_pca_data *pca_data = adap->algo_data;
369	/* The trick here is to check if there is an indirect register
370	 * available. If there is one, we will read the value we first
371	 * wrote on I2C_PCA_IADR. Otherwise, we will read the last value
372	 * we wrote on I2C_PCA_ADR
373	 */
374	pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
375	pca_outw(pca_data, I2C_PCA_IND, 0xAA);
376	pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ITO);
377	pca_outw(pca_data, I2C_PCA_IND, 0x00);
378	pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IADR);
379	if (pca_inw(pca_data, I2C_PCA_IND) == 0xAA) {
380		printk(KERN_INFO "%s: PCA9665 detected.\n", adap->name);
381		return I2C_PCA_CHIP_9665;
382	} else {
383		printk(KERN_INFO "%s: PCA9564 detected.\n", adap->name);
384		return I2C_PCA_CHIP_9564;
385	}
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		/* Ignore the reset function from the module,
460		 * we can use the parallel bus reset
461		 */
462		pca_data->reset_chip = pca9665_reset;
463
464		if (pca_data->i2c_clock > 1265800) {
465			printk(KERN_WARNING "%s: I2C clock speed too high."
466				" Using 1265.8kHz.\n", adap->name);
467			pca_data->i2c_clock = 1265800;
468		}
469
470		if (pca_data->i2c_clock < 60300) {
471			printk(KERN_WARNING "%s: I2C clock speed too low."
472				" Using 60.3kHz.\n", adap->name);
473			pca_data->i2c_clock = 60300;
474		}
475
476		/* To avoid integer overflow, use clock/100 for calculations */
477		clock = pca_clock(pca_data) / 100;
478
479		if (pca_data->i2c_clock > 10000) {
480			mode = I2C_PCA_MODE_TURBO;
481			min_tlow = 14;
482			min_thi  = 5;
483			raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
484		} else if (pca_data->i2c_clock > 4000) {
485			mode = I2C_PCA_MODE_FASTP;
486			min_tlow = 17;
487			min_thi  = 9;
488			raise_fall_time = 22; /* Raise 11e-8s, Fall 11e-8s */
489		} else if (pca_data->i2c_clock > 1000) {
490			mode = I2C_PCA_MODE_FAST;
491			min_tlow = 44;
492			min_thi  = 20;
493			raise_fall_time = 58; /* Raise 29e-8s, Fall 29e-8s */
494		} else {
495			mode = I2C_PCA_MODE_STD;
496			min_tlow = 157;
497			min_thi  = 134;
498			raise_fall_time = 127; /* Raise 29e-8s, Fall 98e-8s */
499		}
500
501		/* The minimum clock that respects the thi/tlow = 134/157 is
502		 * 64800 Hz. Below that, we have to fix the tlow to 255 and
503		 * calculate the thi factor.
504		 */
505		if (clock < 648) {
506			tlow = 255;
507			thi = 1000000 - clock * raise_fall_time;
508			thi /= (I2C_PCA_OSC_PER * clock) - tlow;
509		} else {
510			tlow = (1000000 - clock * raise_fall_time) * min_tlow;
511			tlow /= I2C_PCA_OSC_PER * clock * (min_thi + min_tlow);
512			thi = tlow * min_thi / min_tlow;
513		}
514
515		pca_reset(pca_data);
516
517		printk(KERN_INFO
518		     "%s: Clock frequency is %dHz\n", adap->name, clock * 100);
519
520		pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE);
521		pca_outw(pca_data, I2C_PCA_IND, mode);
522		pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL);
523		pca_outw(pca_data, I2C_PCA_IND, tlow);
524		pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH);
525		pca_outw(pca_data, I2C_PCA_IND, thi);
526
527		pca_set_con(pca_data, I2C_PCA_CON_ENSIO);
528	}
529	udelay(500); /* 500 us for oscilator to stabilise */
530
531	return 0;
532}
533
534/*
535 * registering functions to load algorithms at runtime
536 */
537int i2c_pca_add_bus(struct i2c_adapter *adap)
538{
539	int rval;
540
541	rval = pca_init(adap);
542	if (rval)
543		return rval;
544
545	return i2c_add_adapter(adap);
546}
547EXPORT_SYMBOL(i2c_pca_add_bus);
548
549int i2c_pca_add_numbered_bus(struct i2c_adapter *adap)
550{
551	int rval;
552
553	rval = pca_init(adap);
554	if (rval)
555		return rval;
556
557	return i2c_add_numbered_adapter(adap);
558}
559EXPORT_SYMBOL(i2c_pca_add_numbered_bus);
560
561MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>, "
562	"Wolfram Sang <w.sang@pengutronix.de>");
563MODULE_DESCRIPTION("I2C-Bus PCA9564/PCA9665 algorithm");
564MODULE_LICENSE("GPL");
565
566module_param(i2c_debug, int, 0);
567