1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters
4 *
5 * Copyright (C) 1995-1997 Simon G. Vogl
6 * 1998-2000 Hans Berglund
7 *
8 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and
9 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey
10 * <mbailey@littlefeet-inc.com>
11 *
12 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple
13 * messages, proper stop/repstart signaling during receive, added detect code
14 */
15
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/delay.h>
19 #include <linux/errno.h>
20 #include <linux/i2c.h>
21 #include <linux/i2c-algo-pcf.h>
22 #include <linux/string_choices.h>
23 #include "i2c-algo-pcf.h"
24
25
26 #define DEF_TIMEOUT 16
27
28 /* setting states on the bus with the right timing: */
29
30 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val)
31 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl)
32 #define get_own(adap) adap->getown(adap->data)
33 #define get_clock(adap) adap->getclock(adap->data)
34 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val)
35 #define i2c_inb(adap) adap->getpcf(adap->data, 0)
36
37 /* other auxiliary functions */
38
i2c_start(struct i2c_algo_pcf_data * adap)39 static void i2c_start(struct i2c_algo_pcf_data *adap)
40 {
41 set_pcf(adap, 1, I2C_PCF_START);
42 }
43
i2c_repstart(struct i2c_algo_pcf_data * adap)44 static void i2c_repstart(struct i2c_algo_pcf_data *adap)
45 {
46 set_pcf(adap, 1, I2C_PCF_REPSTART);
47 }
48
i2c_stop(struct i2c_algo_pcf_data * adap)49 static void i2c_stop(struct i2c_algo_pcf_data *adap)
50 {
51 set_pcf(adap, 1, I2C_PCF_STOP);
52 }
53
handle_lab(struct i2c_algo_pcf_data * adap,const int * status)54 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status)
55 {
56 /*
57 * Cleanup from LAB -- reset and enable ESO.
58 * This resets the PCF8584; since we've lost the bus, no
59 * further attempts should be made by callers to clean up
60 * (no i2c_stop() etc.)
61 */
62 set_pcf(adap, 1, I2C_PCF_PIN);
63 set_pcf(adap, 1, I2C_PCF_ESO);
64 /*
65 * We pause for a time period sufficient for any running
66 * I2C transaction to complete -- the arbitration logic won't
67 * work properly until the next START is seen.
68 * It is assumed the bus driver or client has set a proper value.
69 *
70 * REVISIT: should probably use msleep instead of mdelay if we
71 * know we can sleep.
72 */
73 if (adap->lab_mdelay)
74 mdelay(adap->lab_mdelay);
75
76 }
77
wait_for_bb(struct i2c_algo_pcf_data * adap)78 static int wait_for_bb(struct i2c_algo_pcf_data *adap)
79 {
80
81 int timeout = DEF_TIMEOUT;
82 int status;
83
84 status = get_pcf(adap, 1);
85
86 while (!(status & I2C_PCF_BB) && --timeout) {
87 udelay(100); /* wait for 100 us */
88 status = get_pcf(adap, 1);
89 }
90
91 if (timeout == 0) {
92 printk(KERN_ERR "Timeout waiting for Bus Busy\n");
93 return -ETIMEDOUT;
94 }
95
96 return 0;
97 }
98
wait_for_pin(struct i2c_algo_pcf_data * adap,int * status)99 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status)
100 {
101
102 int timeout = DEF_TIMEOUT;
103
104 *status = get_pcf(adap, 1);
105
106 while ((*status & I2C_PCF_PIN) && --timeout) {
107 adap->waitforpin(adap->data);
108 *status = get_pcf(adap, 1);
109 }
110 if (*status & I2C_PCF_LAB) {
111 handle_lab(adap, status);
112 return -EINTR;
113 }
114
115 if (timeout == 0)
116 return -ETIMEDOUT;
117
118 return 0;
119 }
120
121 /*
122 * This should perform the 'PCF8584 initialization sequence' as described
123 * in the Philips IC12 data book (1995, Aug 29).
124 * There should be a 30 clock cycle wait after reset, I assume this
125 * has been fulfilled.
126 * There should be a delay at the end equal to the longest I2C message
127 * to synchronize the BB-bit (in multimaster systems). How long is
128 * this? I assume 1 second is always long enough.
129 *
130 * vdovikin: added detect code for PCF8584
131 */
pcf_init_8584(struct i2c_algo_pcf_data * adap)132 static int pcf_init_8584(struct i2c_algo_pcf_data *adap)
133 {
134 unsigned char temp;
135
136 /* S1=0x80: S0 selected, serial interface off */
137 set_pcf(adap, 1, I2C_PCF_PIN);
138 /*
139 * check to see S1 now used as R/W ctrl -
140 * PCF8584 does that when ESO is zero
141 */
142 temp = get_pcf(adap, 1);
143 if ((temp & 0x7f) != 0)
144 return -ENXIO; /* definitely not PCF8584 */
145
146 /* load own address in S0, effective address is (own << 1) */
147 i2c_outb(adap, get_own(adap));
148 /* check it's really written */
149 temp = i2c_inb(adap);
150 if (temp != get_own(adap))
151 return -ENXIO;
152
153 /* S1=0xA0, next byte in S2 */
154 set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1);
155 /* check to see S2 now selected */
156 temp = get_pcf(adap, 1);
157 if ((temp & 0x7f) != I2C_PCF_ES1)
158 return -ENXIO;
159
160 /* load clock register S2 */
161 i2c_outb(adap, get_clock(adap));
162 /* check it's really written, the only 5 lowest bits does matter */
163 temp = i2c_inb(adap);
164 if ((temp & 0x1f) != get_clock(adap))
165 return -ENXIO;
166
167 /* Enable serial interface, idle, S0 selected */
168 set_pcf(adap, 1, I2C_PCF_IDLE);
169
170 /* check to see PCF is really idled and we can access status register */
171 temp = get_pcf(adap, 1);
172 if (temp != (I2C_PCF_PIN | I2C_PCF_BB))
173 return -ENXIO;
174
175 printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n");
176
177 return 0;
178 }
179
pcf_sendbytes(struct i2c_adapter * i2c_adap,const char * buf,int count,int last)180 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf,
181 int count, int last)
182 {
183 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
184 int wrcount, status, timeout;
185
186 for (wrcount = 0; wrcount < count; ++wrcount) {
187 i2c_outb(adap, buf[wrcount]);
188 timeout = wait_for_pin(adap, &status);
189 if (timeout) {
190 if (timeout == -EINTR)
191 return -EINTR; /* arbitration lost */
192
193 i2c_stop(adap);
194 dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n");
195 return -EREMOTEIO; /* got a better one ?? */
196 }
197 if (status & I2C_PCF_LRB) {
198 i2c_stop(adap);
199 dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n");
200 return -EREMOTEIO; /* got a better one ?? */
201 }
202 }
203 if (last)
204 i2c_stop(adap);
205 else
206 i2c_repstart(adap);
207
208 return wrcount;
209 }
210
pcf_readbytes(struct i2c_adapter * i2c_adap,char * buf,int count,int last)211 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf,
212 int count, int last)
213 {
214 int i, status;
215 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
216 int wfp;
217
218 /* increment number of bytes to read by one -- read dummy byte */
219 for (i = 0; i <= count; i++) {
220
221 wfp = wait_for_pin(adap, &status);
222 if (wfp) {
223 if (wfp == -EINTR)
224 return -EINTR; /* arbitration lost */
225
226 i2c_stop(adap);
227 dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n");
228 return -1;
229 }
230
231 if ((status & I2C_PCF_LRB) && (i != count)) {
232 i2c_stop(adap);
233 dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n");
234 return -1;
235 }
236
237 if (i == count - 1) {
238 set_pcf(adap, 1, I2C_PCF_ESO);
239 } else if (i == count) {
240 if (last)
241 i2c_stop(adap);
242 else
243 i2c_repstart(adap);
244 }
245
246 if (i)
247 buf[i - 1] = i2c_inb(adap);
248 else
249 i2c_inb(adap); /* dummy read */
250 }
251
252 return i - 1;
253 }
254
255
pcf_send_address(struct i2c_algo_pcf_data * adap,struct i2c_msg * msg)256 static void pcf_send_address(struct i2c_algo_pcf_data *adap,
257 struct i2c_msg *msg)
258 {
259 unsigned char addr = i2c_8bit_addr_from_msg(msg);
260
261 if (msg->flags & I2C_M_REV_DIR_ADDR)
262 addr ^= 1;
263 i2c_outb(adap, addr);
264 }
265
pcf_xfer(struct i2c_adapter * i2c_adap,struct i2c_msg * msgs,int num)266 static int pcf_xfer(struct i2c_adapter *i2c_adap,
267 struct i2c_msg *msgs,
268 int num)
269 {
270 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data;
271 struct i2c_msg *pmsg;
272 int i;
273 int timeout, status;
274
275 if (adap->xfer_begin)
276 adap->xfer_begin(adap->data);
277
278 /* Check for bus busy */
279 timeout = wait_for_bb(adap);
280 if (timeout) {
281 i = -EIO;
282 goto out;
283 }
284
285 for (i = 0; i < num; i++) {
286 int ret;
287
288 pmsg = &msgs[i];
289 pcf_send_address(adap, pmsg);
290
291 /* Send START */
292 if (i == 0)
293 i2c_start(adap);
294
295 /* Wait for PIN (pending interrupt NOT) */
296 timeout = wait_for_pin(adap, &status);
297 if (timeout) {
298 if (timeout == -EINTR) {
299 /* arbitration lost */
300 i = -EINTR;
301 goto out;
302 }
303 i2c_stop(adap);
304 i = -EREMOTEIO;
305 goto out;
306 }
307
308 /* Check LRB (last rcvd bit - slave ack) */
309 if (status & I2C_PCF_LRB) {
310 i2c_stop(adap);
311 i = -EREMOTEIO;
312 goto out;
313 }
314
315
316 if (pmsg->flags & I2C_M_RD) {
317 ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len,
318 (i + 1 == num));
319 } else {
320 ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len,
321 (i + 1 == num));
322 }
323
324 if (ret < 0)
325 goto out;
326 }
327
328 out:
329 if (adap->xfer_end)
330 adap->xfer_end(adap->data);
331 return i;
332 }
333
pcf_func(struct i2c_adapter * adap)334 static u32 pcf_func(struct i2c_adapter *adap)
335 {
336 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
337 I2C_FUNC_PROTOCOL_MANGLING;
338 }
339
340 /* exported algorithm data: */
341 static const struct i2c_algorithm pcf_algo = {
342 .xfer = pcf_xfer,
343 .functionality = pcf_func,
344 };
345
346 /*
347 * registering functions to load algorithms at runtime
348 */
i2c_pcf_add_bus(struct i2c_adapter * adap)349 int i2c_pcf_add_bus(struct i2c_adapter *adap)
350 {
351 struct i2c_algo_pcf_data *pcf_adap = adap->algo_data;
352 int rval;
353
354 /* register new adapter to i2c module... */
355 adap->algo = &pcf_algo;
356
357 rval = pcf_init_8584(pcf_adap);
358 if (rval)
359 return rval;
360
361 rval = i2c_add_adapter(adap);
362
363 return rval;
364 }
365 EXPORT_SYMBOL(i2c_pcf_add_bus);
366
367 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>");
368 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm");
369 MODULE_LICENSE("GPL");
370