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
37 static int i2c_debug=0;
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 occured
53 */
54 static 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 occured
68 */
69 static 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 the idle state (0xf8). Hence we don't need to
86 * pca_wait here.
87 */
88 static 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 */
102 static 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 */
127 static 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 */
145 static 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 */
157 static 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 */
174 static 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
180 static 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
190 state = pca_status(adap);
191 if ( state != 0xF8 ) {
192 dev_dbg(&i2c_adap->dev, "bus is not idle. status is %#04x\n", state );
193 /* FIXME: what to do. Force stop ? */
194 return -EREMOTEIO;
195 }
196
197 DEB1("{{{ XFER %d messages\n", num);
198
199 if (i2c_debug>=2) {
200 for (curmsg = 0; curmsg < num; curmsg++) {
201 int addr, i;
202 msg = &msgs[curmsg];
203
204 addr = (0x7f & msg->addr) ;
205
206 if (msg->flags & I2C_M_RD )
207 printk(KERN_INFO " [%02d] RD %d bytes from %#02x [%#02x, ...]\n",
208 curmsg, msg->len, addr, (addr<<1) | 1);
209 else {
210 printk(KERN_INFO " [%02d] WR %d bytes to %#02x [%#02x%s",
211 curmsg, msg->len, addr, addr<<1,
212 msg->len == 0 ? "" : ", ");
213 for(i=0; i < msg->len; i++)
214 printk("%#04x%s", msg->buf[i], i == msg->len - 1 ? "" : ", ");
215 printk("]\n");
216 }
217 }
218 }
219
220 curmsg = 0;
221 while (curmsg < num) {
222 state = pca_status(adap);
223
224 DEB3("STATE is 0x%02x\n", state);
225 msg = &msgs[curmsg];
226
227 switch (state) {
228 case 0xf8: /* On reset or stop the bus is idle */
229 pca_start(adap);
230 break;
231
232 case 0x08: /* A START condition has been transmitted */
233 case 0x10: /* A repeated start condition has been transmitted */
234 pca_address(adap, msg);
235 break;
236
237 case 0x18: /* SLA+W has been transmitted; ACK has been received */
238 case 0x28: /* Data byte in I2CDAT has been transmitted; ACK has been received */
239 if (numbytes < msg->len) {
240 pca_tx_byte(adap, msg->buf[numbytes]);
241 numbytes++;
242 break;
243 }
244 curmsg++; numbytes = 0;
245 if (curmsg == num)
246 pca_stop(adap);
247 else
248 pca_repeated_start(adap);
249 break;
250
251 case 0x20: /* SLA+W has been transmitted; NOT ACK has been received */
252 DEB2("NOT ACK received after SLA+W\n");
253 pca_stop(adap);
254 return -EREMOTEIO;
255
256 case 0x40: /* SLA+R has been transmitted; ACK has been received */
257 pca_rx_ack(adap, msg->len > 1);
258 break;
259
260 case 0x50: /* Data bytes has been received; ACK has been returned */
261 if (numbytes < msg->len) {
262 pca_rx_byte(adap, &msg->buf[numbytes], 1);
263 numbytes++;
264 pca_rx_ack(adap, numbytes < msg->len - 1);
265 break;
266 }
267 curmsg++; numbytes = 0;
268 if (curmsg == num)
269 pca_stop(adap);
270 else
271 pca_repeated_start(adap);
272 break;
273
274 case 0x48: /* SLA+R has been transmitted; NOT ACK has been received */
275 DEB2("NOT ACK received after SLA+R\n");
276 pca_stop(adap);
277 return -EREMOTEIO;
278
279 case 0x30: /* Data byte in I2CDAT has been transmitted; NOT ACK has been received */
280 DEB2("NOT ACK received after data byte\n");
281 return -EREMOTEIO;
282
283 case 0x38: /* Arbitration lost during SLA+W, SLA+R or data bytes */
284 DEB2("Arbitration lost\n");
285 return -EREMOTEIO;
286
287 case 0x58: /* Data byte has been received; NOT ACK has been returned */
288 if ( numbytes == msg->len - 1 ) {
289 pca_rx_byte(adap, &msg->buf[numbytes], 0);
290 curmsg++; numbytes = 0;
291 if (curmsg == num)
292 pca_stop(adap);
293 else
294 pca_repeated_start(adap);
295 } else {
296 DEB2("NOT ACK sent after data byte received. "
297 "Not final byte. numbytes %d. len %d\n",
298 numbytes, msg->len);
299 pca_stop(adap);
300 return -EREMOTEIO;
301 }
302 break;
303 case 0x70: /* Bus error - SDA stuck low */
304 DEB2("BUS ERROR - SDA Stuck low\n");
305 pca_reset(adap);
306 return -EREMOTEIO;
307 case 0x90: /* Bus error - SCL stuck low */
308 DEB2("BUS ERROR - SCL Stuck low\n");
309 pca_reset(adap);
310 return -EREMOTEIO;
311 case 0x00: /* Bus error during master or slave mode due to illegal START or STOP condition */
312 DEB2("BUS ERROR - Illegal START or STOP\n");
313 pca_reset(adap);
314 return -EREMOTEIO;
315 default:
316 printk(KERN_ERR DRIVER ": unhandled SIO state 0x%02x\n", state);
317 break;
318 }
319
320 }
321
322 DEB1(KERN_CRIT "}}} transfered %d messages. "
323 "status is %#04x. control is %#04x\n",
324 num, pca_status(adap),
325 pca_get_con(adap));
326 return curmsg;
327 }
328
329 static u32 pca_func(struct i2c_adapter *adap)
330 {
331 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
332 }
333
334 static int pca_init(struct i2c_algo_pca_data *adap)
335 {
336 static int freqs[] = {330,288,217,146,88,59,44,36};
337 int own, clock;
338
339 own = pca_own(adap);
340 clock = pca_clock(adap);
341 DEB1(KERN_INFO DRIVER ": own address is %#04x\n", own);
342 DEB1(KERN_INFO DRIVER ": clock freqeuncy is %dkHz\n", freqs[clock]);
343
344 pca_outw(adap, I2C_PCA_ADR, own << 1);
345
346 pca_set_con(adap, I2C_PCA_CON_ENSIO | clock);
347 udelay(500); /* 500 µs for oscilator to stabilise */
348
349 return 0;
350 }
351
352 static struct i2c_algorithm pca_algo = {
353 .name = "PCA9564 algorithm",
354 .id = I2C_ALGO_PCA,
355 .master_xfer = pca_xfer,
356 .functionality = pca_func,
357 };
358
359 /*
360 * registering functions to load algorithms at runtime
361 */
362 int i2c_pca_add_bus(struct i2c_adapter *adap)
363 {
364 struct i2c_algo_pca_data *pca_adap = adap->algo_data;
365 int rval;
366
367 /* register new adapter to i2c module... */
368
369 adap->id |= pca_algo.id;
370 adap->algo = &pca_algo;
371
372 adap->timeout = 100; /* default values, should */
373 adap->retries = 3; /* be replaced by defines */
374
375 rval = pca_init(pca_adap);
376
377 if (!rval)
378 i2c_add_adapter(adap);
379
380 return rval;
381 }
382
383 int i2c_pca_del_bus(struct i2c_adapter *adap)
384 {
385 return i2c_del_adapter(adap);
386 }
387
388 EXPORT_SYMBOL(i2c_pca_add_bus);
389 EXPORT_SYMBOL(i2c_pca_del_bus);
390
391 MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
392 MODULE_DESCRIPTION("I2C-Bus PCA9564 algorithm");
393 MODULE_LICENSE("GPL");
394
395 module_param(i2c_debug, int, 0);
396
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