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 "i2c-algo-pcf.h" |
23 | |
24 | |
25 | #define DEB2(x) if (i2c_debug >= 2) x |
26 | #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */ |
27 | #define DEBPROTO(x) if (i2c_debug >= 9) x; |
28 | /* debug the protocol by showing transferred bits */ |
29 | #define DEF_TIMEOUT 16 |
30 | |
31 | /* |
32 | * module parameters: |
33 | */ |
34 | static int i2c_debug; |
35 | |
36 | /* setting states on the bus with the right timing: */ |
37 | |
38 | #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val) |
39 | #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl) |
40 | #define get_own(adap) adap->getown(adap->data) |
41 | #define get_clock(adap) adap->getclock(adap->data) |
42 | #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val) |
43 | #define i2c_inb(adap) adap->getpcf(adap->data, 0) |
44 | |
45 | /* other auxiliary functions */ |
46 | |
47 | static void i2c_start(struct i2c_algo_pcf_data *adap) |
48 | { |
49 | DEBPROTO(printk(KERN_DEBUG "S " )); |
50 | set_pcf(adap, 1, I2C_PCF_START); |
51 | } |
52 | |
53 | static void i2c_repstart(struct i2c_algo_pcf_data *adap) |
54 | { |
55 | DEBPROTO(printk(" Sr " )); |
56 | set_pcf(adap, 1, I2C_PCF_REPSTART); |
57 | } |
58 | |
59 | static void i2c_stop(struct i2c_algo_pcf_data *adap) |
60 | { |
61 | DEBPROTO(printk("P\n" )); |
62 | set_pcf(adap, 1, I2C_PCF_STOP); |
63 | } |
64 | |
65 | static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status) |
66 | { |
67 | DEB2(printk(KERN_INFO |
68 | "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n" , |
69 | *status)); |
70 | /* |
71 | * Cleanup from LAB -- reset and enable ESO. |
72 | * This resets the PCF8584; since we've lost the bus, no |
73 | * further attempts should be made by callers to clean up |
74 | * (no i2c_stop() etc.) |
75 | */ |
76 | set_pcf(adap, 1, I2C_PCF_PIN); |
77 | set_pcf(adap, 1, I2C_PCF_ESO); |
78 | /* |
79 | * We pause for a time period sufficient for any running |
80 | * I2C transaction to complete -- the arbitration logic won't |
81 | * work properly until the next START is seen. |
82 | * It is assumed the bus driver or client has set a proper value. |
83 | * |
84 | * REVISIT: should probably use msleep instead of mdelay if we |
85 | * know we can sleep. |
86 | */ |
87 | if (adap->lab_mdelay) |
88 | mdelay(adap->lab_mdelay); |
89 | |
90 | DEB2(printk(KERN_INFO |
91 | "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n" , |
92 | get_pcf(adap, 1))); |
93 | } |
94 | |
95 | static int wait_for_bb(struct i2c_algo_pcf_data *adap) |
96 | { |
97 | |
98 | int timeout = DEF_TIMEOUT; |
99 | int status; |
100 | |
101 | status = get_pcf(adap, 1); |
102 | |
103 | while (!(status & I2C_PCF_BB) && --timeout) { |
104 | udelay(100); /* wait for 100 us */ |
105 | status = get_pcf(adap, 1); |
106 | } |
107 | |
108 | if (timeout == 0) { |
109 | printk(KERN_ERR "Timeout waiting for Bus Busy\n" ); |
110 | return -ETIMEDOUT; |
111 | } |
112 | |
113 | return 0; |
114 | } |
115 | |
116 | static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) |
117 | { |
118 | |
119 | int timeout = DEF_TIMEOUT; |
120 | |
121 | *status = get_pcf(adap, 1); |
122 | |
123 | while ((*status & I2C_PCF_PIN) && --timeout) { |
124 | adap->waitforpin(adap->data); |
125 | *status = get_pcf(adap, 1); |
126 | } |
127 | if (*status & I2C_PCF_LAB) { |
128 | handle_lab(adap, status); |
129 | return -EINTR; |
130 | } |
131 | |
132 | if (timeout == 0) |
133 | return -ETIMEDOUT; |
134 | |
135 | return 0; |
136 | } |
137 | |
138 | /* |
139 | * This should perform the 'PCF8584 initialization sequence' as described |
140 | * in the Philips IC12 data book (1995, Aug 29). |
141 | * There should be a 30 clock cycle wait after reset, I assume this |
142 | * has been fulfilled. |
143 | * There should be a delay at the end equal to the longest I2C message |
144 | * to synchronize the BB-bit (in multimaster systems). How long is |
145 | * this? I assume 1 second is always long enough. |
146 | * |
147 | * vdovikin: added detect code for PCF8584 |
148 | */ |
149 | static int pcf_init_8584 (struct i2c_algo_pcf_data *adap) |
150 | { |
151 | unsigned char temp; |
152 | |
153 | DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n" , |
154 | get_pcf(adap, 1))); |
155 | |
156 | /* S1=0x80: S0 selected, serial interface off */ |
157 | set_pcf(adap, 1, I2C_PCF_PIN); |
158 | /* |
159 | * check to see S1 now used as R/W ctrl - |
160 | * PCF8584 does that when ESO is zero |
161 | */ |
162 | if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) { |
163 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n" , temp)); |
164 | return -ENXIO; /* definitely not PCF8584 */ |
165 | } |
166 | |
167 | /* load own address in S0, effective address is (own << 1) */ |
168 | i2c_outb(adap, get_own(adap)); |
169 | /* check it's really written */ |
170 | if ((temp = i2c_inb(adap)) != get_own(adap)) { |
171 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n" , temp)); |
172 | return -ENXIO; |
173 | } |
174 | |
175 | /* S1=0xA0, next byte in S2 */ |
176 | set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1); |
177 | /* check to see S2 now selected */ |
178 | if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) { |
179 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n" , temp)); |
180 | return -ENXIO; |
181 | } |
182 | |
183 | /* load clock register S2 */ |
184 | i2c_outb(adap, get_clock(adap)); |
185 | /* check it's really written, the only 5 lowest bits does matter */ |
186 | if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) { |
187 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n" , temp)); |
188 | return -ENXIO; |
189 | } |
190 | |
191 | /* Enable serial interface, idle, S0 selected */ |
192 | set_pcf(adap, 1, I2C_PCF_IDLE); |
193 | |
194 | /* check to see PCF is really idled and we can access status register */ |
195 | if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) { |
196 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n" , temp)); |
197 | return -ENXIO; |
198 | } |
199 | |
200 | printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n" ); |
201 | |
202 | return 0; |
203 | } |
204 | |
205 | static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf, |
206 | int count, int last) |
207 | { |
208 | struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; |
209 | int wrcount, status, timeout; |
210 | |
211 | for (wrcount=0; wrcount<count; ++wrcount) { |
212 | DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n" , |
213 | buf[wrcount] & 0xff)); |
214 | i2c_outb(adap, buf[wrcount]); |
215 | timeout = wait_for_pin(adap, status: &status); |
216 | if (timeout) { |
217 | if (timeout == -EINTR) |
218 | return -EINTR; /* arbitration lost */ |
219 | |
220 | i2c_stop(adap); |
221 | dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n" ); |
222 | return -EREMOTEIO; /* got a better one ?? */ |
223 | } |
224 | if (status & I2C_PCF_LRB) { |
225 | i2c_stop(adap); |
226 | dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n" ); |
227 | return -EREMOTEIO; /* got a better one ?? */ |
228 | } |
229 | } |
230 | if (last) |
231 | i2c_stop(adap); |
232 | else |
233 | i2c_repstart(adap); |
234 | |
235 | return wrcount; |
236 | } |
237 | |
238 | static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf, |
239 | int count, int last) |
240 | { |
241 | int i, status; |
242 | struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; |
243 | int wfp; |
244 | |
245 | /* increment number of bytes to read by one -- read dummy byte */ |
246 | for (i = 0; i <= count; i++) { |
247 | |
248 | if ((wfp = wait_for_pin(adap, status: &status))) { |
249 | if (wfp == -EINTR) |
250 | return -EINTR; /* arbitration lost */ |
251 | |
252 | i2c_stop(adap); |
253 | dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n" ); |
254 | return -1; |
255 | } |
256 | |
257 | if ((status & I2C_PCF_LRB) && (i != count)) { |
258 | i2c_stop(adap); |
259 | dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n" ); |
260 | return -1; |
261 | } |
262 | |
263 | if (i == count - 1) { |
264 | set_pcf(adap, 1, I2C_PCF_ESO); |
265 | } else if (i == count) { |
266 | if (last) |
267 | i2c_stop(adap); |
268 | else |
269 | i2c_repstart(adap); |
270 | } |
271 | |
272 | if (i) |
273 | buf[i - 1] = i2c_inb(adap); |
274 | else |
275 | i2c_inb(adap); /* dummy read */ |
276 | } |
277 | |
278 | return i - 1; |
279 | } |
280 | |
281 | |
282 | static int pcf_doAddress(struct i2c_algo_pcf_data *adap, |
283 | struct i2c_msg *msg) |
284 | { |
285 | unsigned char addr = i2c_8bit_addr_from_msg(msg); |
286 | |
287 | if (msg->flags & I2C_M_REV_DIR_ADDR) |
288 | addr ^= 1; |
289 | i2c_outb(adap, addr); |
290 | |
291 | return 0; |
292 | } |
293 | |
294 | static int pcf_xfer(struct i2c_adapter *i2c_adap, |
295 | struct i2c_msg *msgs, |
296 | int num) |
297 | { |
298 | struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; |
299 | struct i2c_msg *pmsg; |
300 | int i; |
301 | int ret=0, timeout, status; |
302 | |
303 | if (adap->xfer_begin) |
304 | adap->xfer_begin(adap->data); |
305 | |
306 | /* Check for bus busy */ |
307 | timeout = wait_for_bb(adap); |
308 | if (timeout) { |
309 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: " |
310 | "Timeout waiting for BB in pcf_xfer\n" );) |
311 | i = -EIO; |
312 | goto out; |
313 | } |
314 | |
315 | for (i = 0;ret >= 0 && i < num; i++) { |
316 | pmsg = &msgs[i]; |
317 | |
318 | DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n" , |
319 | pmsg->flags & I2C_M_RD ? "read" : "write" , |
320 | pmsg->len, pmsg->addr, i + 1, num);) |
321 | |
322 | ret = pcf_doAddress(adap, msg: pmsg); |
323 | |
324 | /* Send START */ |
325 | if (i == 0) |
326 | i2c_start(adap); |
327 | |
328 | /* Wait for PIN (pending interrupt NOT) */ |
329 | timeout = wait_for_pin(adap, status: &status); |
330 | if (timeout) { |
331 | if (timeout == -EINTR) { |
332 | /* arbitration lost */ |
333 | i = -EINTR; |
334 | goto out; |
335 | } |
336 | i2c_stop(adap); |
337 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting " |
338 | "for PIN(1) in pcf_xfer\n" );) |
339 | i = -EREMOTEIO; |
340 | goto out; |
341 | } |
342 | |
343 | /* Check LRB (last rcvd bit - slave ack) */ |
344 | if (status & I2C_PCF_LRB) { |
345 | i2c_stop(adap); |
346 | DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n" );) |
347 | i = -EREMOTEIO; |
348 | goto out; |
349 | } |
350 | |
351 | DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n" , |
352 | i, msgs[i].addr, msgs[i].flags, msgs[i].len);) |
353 | |
354 | if (pmsg->flags & I2C_M_RD) { |
355 | ret = pcf_readbytes(i2c_adap, buf: pmsg->buf, count: pmsg->len, |
356 | last: (i + 1 == num)); |
357 | |
358 | if (ret != pmsg->len) { |
359 | DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: " |
360 | "only read %d bytes.\n" ,ret)); |
361 | } else { |
362 | DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n" ,ret)); |
363 | } |
364 | } else { |
365 | ret = pcf_sendbytes(i2c_adap, buf: pmsg->buf, count: pmsg->len, |
366 | last: (i + 1 == num)); |
367 | |
368 | if (ret != pmsg->len) { |
369 | DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: " |
370 | "only wrote %d bytes.\n" ,ret)); |
371 | } else { |
372 | DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n" ,ret)); |
373 | } |
374 | } |
375 | } |
376 | |
377 | out: |
378 | if (adap->xfer_end) |
379 | adap->xfer_end(adap->data); |
380 | return i; |
381 | } |
382 | |
383 | static u32 pcf_func(struct i2c_adapter *adap) |
384 | { |
385 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | |
386 | I2C_FUNC_PROTOCOL_MANGLING; |
387 | } |
388 | |
389 | /* exported algorithm data: */ |
390 | static const struct i2c_algorithm pcf_algo = { |
391 | .master_xfer = pcf_xfer, |
392 | .functionality = pcf_func, |
393 | }; |
394 | |
395 | /* |
396 | * registering functions to load algorithms at runtime |
397 | */ |
398 | int i2c_pcf_add_bus(struct i2c_adapter *adap) |
399 | { |
400 | struct i2c_algo_pcf_data *pcf_adap = adap->algo_data; |
401 | int rval; |
402 | |
403 | DEB2(dev_dbg(&adap->dev, "hw routines registered.\n" )); |
404 | |
405 | /* register new adapter to i2c module... */ |
406 | adap->algo = &pcf_algo; |
407 | |
408 | if ((rval = pcf_init_8584(adap: pcf_adap))) |
409 | return rval; |
410 | |
411 | rval = i2c_add_adapter(adap); |
412 | |
413 | return rval; |
414 | } |
415 | EXPORT_SYMBOL(i2c_pcf_add_bus); |
416 | |
417 | MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>" ); |
418 | MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm" ); |
419 | MODULE_LICENSE("GPL" ); |
420 | |
421 | module_param(i2c_debug, int, S_IRUGO | S_IWUSR); |
422 | MODULE_PARM_DESC(i2c_debug, |
423 | "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol" ); |
424 | |