1/*
2 *  i2c-algo-pca.c i2c driver algorithms for PCA9564 adapters
3 *    Copyright (C) 2004 Arcom Control Systems
4 *
5 *  This program is free software; you can redistribute it and/or modify
6 *  it under the terms of the GNU General Public License as published by
7 *  the Free Software Foundation; either version 2 of the License, or
8 *  (at your option) any later version.
9 *
10 *  This program is distributed in the hope that it will be useful,
11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 *  GNU General Public License for more details.
14 *
15 *  You should have received a copy of the GNU General Public License
16 *  along with this program; if not, write to the Free Software
17 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 */
19
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/moduleparam.h>
23#include <linux/delay.h>
24#include <linux/slab.h>
25#include <linux/init.h>
26#include <linux/errno.h>
27#include <linux/i2c.h>
28#include <linux/i2c-algo-pca.h>
29#include "i2c-algo-pca.h"
30
31#define DRIVER "i2c-algo-pca"
32
33#define DEB1(fmt, args...) do { if (i2c_debug>=1) printk(fmt, ## args); } while(0)
34#define DEB2(fmt, args...) do { if (i2c_debug>=2) printk(fmt, ## args); } while(0)
35#define DEB3(fmt, args...) do { if (i2c_debug>=3) printk(fmt, ## args); } while(0)
36
37static int i2c_debug;
38
39#define pca_outw(adap, reg, val) adap->write_byte(adap, reg, val)
40#define pca_inw(adap, reg) adap->read_byte(adap, reg)
41
42#define pca_status(adap) pca_inw(adap, I2C_PCA_STA)
43#define pca_clock(adap) adap->get_clock(adap)
44#define pca_own(adap) adap->get_own(adap)
45#define pca_set_con(adap, val) pca_outw(adap, I2C_PCA_CON, val)
46#define pca_get_con(adap) pca_inw(adap, I2C_PCA_CON)
47#define pca_wait(adap) adap->wait_for_interrupt(adap)
48
49/*
50 * Generate a start condition on the i2c bus.
51 *
52 * returns after the start condition has occurred
53 */
54static void pca_start(struct i2c_algo_pca_data *adap)
55{
56	int sta = pca_get_con(adap);
57	DEB2("=== START\n");
58	sta |= I2C_PCA_CON_STA;
59	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
60	pca_set_con(adap, sta);
61	pca_wait(adap);
62}
63
64/*
65 * Generate a repeated start condition on the i2c bus
66 *
67 * return after the repeated start condition has occurred
68 */
69static void pca_repeated_start(struct i2c_algo_pca_data *adap)
70{
71	int sta = pca_get_con(adap);
72	DEB2("=== REPEATED START\n");
73	sta |= I2C_PCA_CON_STA;
74	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_SI);
75	pca_set_con(adap, sta);
76	pca_wait(adap);
77}
78
79/*
80 * Generate a stop condition on the i2c bus
81 *
82 * returns after the stop condition has been generated
83 *
84 * STOPs do not generate an interrupt or set the SI flag, since the
85 * part returns the idle state (0xf8). Hence we don't need to
86 * pca_wait here.
87 */
88static void pca_stop(struct i2c_algo_pca_data *adap)
89{
90	int sta = pca_get_con(adap);
91	DEB2("=== STOP\n");
92	sta |= I2C_PCA_CON_STO;
93	sta &= ~(I2C_PCA_CON_STA|I2C_PCA_CON_SI);
94	pca_set_con(adap, sta);
95}
96
97/*
98 * Send the slave address and R/W bit
99 *
100 * returns after the address has been sent
101 */
102static void pca_address(struct i2c_algo_pca_data *adap,
103			struct i2c_msg *msg)
104{
105	int sta = pca_get_con(adap);
106	int addr;
107
108	addr = ( (0x7f & msg->addr) << 1 );
109	if (msg->flags & I2C_M_RD )
110		addr |= 1;
111	DEB2("=== SLAVE ADDRESS %#04x+%c=%#04x\n",
112	     msg->addr, msg->flags & I2C_M_RD ? 'R' : 'W', addr);
113
114	pca_outw(adap, I2C_PCA_DAT, addr);
115
116	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
117	pca_set_con(adap, sta);
118
119	pca_wait(adap);
120}
121
122/*
123 * Transmit a byte.
124 *
125 * Returns after the byte has been transmitted
126 */
127static void pca_tx_byte(struct i2c_algo_pca_data *adap,
128			__u8 b)
129{
130	int sta = pca_get_con(adap);
131	DEB2("=== WRITE %#04x\n", b);
132	pca_outw(adap, I2C_PCA_DAT, b);
133
134	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI);
135	pca_set_con(adap, sta);
136
137	pca_wait(adap);
138}
139
140/*
141 * Receive a byte
142 *
143 * returns immediately.
144 */
145static void pca_rx_byte(struct i2c_algo_pca_data *adap,
146			__u8 *b, int ack)
147{
148	*b = pca_inw(adap, I2C_PCA_DAT);
149	DEB2("=== READ %#04x %s\n", *b, ack ? "ACK" : "NACK");
150}
151
152/*
153 * Setup ACK or NACK for next received byte and wait for it to arrive.
154 *
155 * Returns after next byte has arrived.
156 */
157static void pca_rx_ack(struct i2c_algo_pca_data *adap,
158		       int ack)
159{
160	int sta = pca_get_con(adap);
161
162	sta &= ~(I2C_PCA_CON_STO|I2C_PCA_CON_STA|I2C_PCA_CON_SI|I2C_PCA_CON_AA);
163
164	if ( ack )
165		sta |= I2C_PCA_CON_AA;
166
167	pca_set_con(adap, sta);
168	pca_wait(adap);
169}
170
171/*
172 * Reset the i2c bus / SIO
173 */
174static void pca_reset(struct i2c_algo_pca_data *adap)
175{
176	/* apparently only an external reset will do it. not a lot can be done */
177	printk(KERN_ERR DRIVER ": Haven't figured out how to do a reset yet\n");
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 timeout = 100;
191
192	while ((state = pca_status(adap)) != 0xf8 && timeout--) {
193		msleep(10);
194	}
195	if (state != 0xf8) {
196		dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state);
197		return -EIO;
198	}
199
200	DEB1("{{{ XFER %d messages\n", num);
201
202	if (i2c_debug>=2) {
203		for (curmsg = 0; curmsg < num; curmsg++) {
204			int addr, i;
205			msg = &msgs[curmsg];
206
207			addr = (0x7f & msg->addr) ;
208
209			if (msg->flags & I2C_M_RD )
210				printk(KERN_INFO "    [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
211				       curmsg, msg->len, addr, (addr<<1) | 1);
212			else {
213				printk(KERN_INFO "    [%02d] WR %d bytes to %#02x [%#02x%s",
214				       curmsg, msg->len, addr, addr<<1,
215				       msg->len == 0 ? "" : ", ");
216				for(i=0; i < msg->len; i++)
217					printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
218				printk("]\n");
219			}
220		}
221	}
222
223	curmsg = 0;
224	ret = -EREMOTEIO;
225	while (curmsg < num) {
226		state = pca_status(adap);
227
228		DEB3("STATE is 0x%02x\n", state);
229		msg = &msgs[curmsg];
230
231		switch (state) {
232		case 0xf8: /* On reset or stop the bus is idle */
233			pca_start(adap);
234			break;
235
236		case 0x08: /* A START condition has been transmitted */
237		case 0x10: /* A repeated start condition has been transmitted */
238			pca_address(adap, msg);
239			break;
240
241		case 0x18: /* SLA+W has been transmitted; ACK has been received */
242		case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
243			if (numbytes < msg->len) {
244				pca_tx_byte(adap, msg->buf[numbytes]);
245				numbytes++;
246				break;
247			}
248			curmsg++; numbytes = 0;
249			if (curmsg == num)
250				pca_stop(adap);
251			else
252				pca_repeated_start(adap);
253			break;
254
255		case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
256			DEB2("NOT ACK received after SLA+W\n");
257			pca_stop(adap);
258			goto out;
259
260		case 0x40: /* SLA+R has been transmitted; ACK has been received */
261			pca_rx_ack(adap, msg->len > 1);
262			break;
263
264		case 0x50: /* Data bytes has been received; ACK has been returned */
265			if (numbytes < msg->len) {
266				pca_rx_byte(adap, &msg->buf[numbytes], 1);
267				numbytes++;
268				pca_rx_ack(adap, numbytes < msg->len - 1);
269				break;
270			}
271			curmsg++; numbytes = 0;
272			if (curmsg == num)
273				pca_stop(adap);
274			else
275				pca_repeated_start(adap);
276			break;
277
278		case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
279			DEB2("NOT ACK received after SLA+R\n");
280			pca_stop(adap);
281			goto out;
282
283		case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
284			DEB2("NOT ACK received after data byte\n");
285			goto out;
286
287		case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
288			DEB2("Arbitration lost\n");
289			goto out;
290
291		case 0x58: /* Data byte has been received; NOT ACK has been returned */
292			if ( numbytes == msg->len - 1 ) {
293				pca_rx_byte(adap, &msg->buf[numbytes], 0);
294				curmsg++; numbytes = 0;
295				if (curmsg == num)
296					pca_stop(adap);
297				else
298					pca_repeated_start(adap);
299			} else {
300				DEB2("NOT ACK sent after data byte received. "
301				     "Not final byte. numbytes %d. len %d\n",
302				     numbytes, msg->len);
303				pca_stop(adap);
304				goto out;
305			}
306			break;
307		case 0x70: /* Bus error - SDA stuck low */
308			DEB2("BUS ERROR - SDA Stuck low\n");
309			pca_reset(adap);
310			goto out;
311		case 0x90: /* Bus error - SCL stuck low */
312			DEB2("BUS ERROR - SCL Stuck low\n");
313			pca_reset(adap);
314			goto out;
315		case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
316			DEB2("BUS ERROR - Illegal START or STOP\n");
317			pca_reset(adap);
318			goto out;
319		default:
320			printk(KERN_ERR DRIVER ": unhandled SIO state 0x%02x\n", state);
321			break;
322		}
323
324	}
325
326	ret = curmsg;
327 out:
328	DEB1(KERN_CRIT "}}} transfered %d/%d messages. "
329	     "status is %#04x. control is %#04x\n",
330	     curmsg, num, pca_status(adap),
331	     pca_get_con(adap));
332	return ret;
333}
334
335static u32 pca_func(struct i2c_adapter *adap)
336{
337        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
338}
339
340static int pca_init(struct i2c_algo_pca_data *adap)
341{
342	static int freqs[] = {330,288,217,146,88,59,44,36};
343	int own, clock;
344
345	own = pca_own(adap);
346	clock = pca_clock(adap);
347	DEB1(KERN_INFO DRIVER ": own address is %#04x\n", own);
348	DEB1(KERN_INFO DRIVER ": clock freqeuncy is %dkHz\n", freqs[clock]);
349
350	pca_outw(adap, I2C_PCA_ADR, own << 1);
351
352	pca_set_con(adap, I2C_PCA_CON_ENSIO | clock);
353	udelay(500); /* 500 �s for oscilator to stabilise */
354
355	return 0;
356}
357
358static const struct i2c_algorithm pca_algo = {
359	.master_xfer	= pca_xfer,
360	.functionality	= pca_func,
361};
362
363/*
364 * registering functions to load algorithms at runtime
365 */
366int i2c_pca_add_bus(struct i2c_adapter *adap)
367{
368	struct i2c_algo_pca_data *pca_adap = adap->algo_data;
369	int rval;
370
371	/* register new adapter to i2c module... */
372	adap->algo = &pca_algo;
373
374	adap->timeout = 100;		/* default values, should	*/
375	adap->retries = 3;		/* be replaced by defines	*/
376
377	if ((rval = pca_init(pca_adap)))
378		return rval;
379
380	rval = i2c_add_adapter(adap);
381
382	return rval;
383}
384EXPORT_SYMBOL(i2c_pca_add_bus);
385
386MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
387MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm");
388MODULE_LICENSE("GPL");
389
390module_param(i2c_debug, int, 0);
391