1 /* 2 * i2c-algo-pcf.c i2c driver algorithms for PCF8584 adapters 3 * 4 * Copyright (C) 1995-1997 Simon G. Vogl 5 * 1998-2000 Hans Berglund 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and 18 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey 19 * <mbailey@littlefeet-inc.com> 20 * 21 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple 22 * messages, proper stop/repstart signaling during receive, added detect code 23 */ 24 25 #include <linux/kernel.h> 26 #include <linux/module.h> 27 #include <linux/delay.h> 28 #include <linux/errno.h> 29 #include <linux/i2c.h> 30 #include <linux/i2c-algo-pcf.h> 31 #include "i2c-algo-pcf.h" 32 33 34 #define DEB2(x) if (i2c_debug >= 2) x 35 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */ 36 #define DEBPROTO(x) if (i2c_debug >= 9) x; 37 /* debug the protocol by showing transferred bits */ 38 #define DEF_TIMEOUT 16 39 40 /* 41 * module parameters: 42 */ 43 static int i2c_debug; 44 45 /* setting states on the bus with the right timing: */ 46 47 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val) 48 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl) 49 #define get_own(adap) adap->getown(adap->data) 50 #define get_clock(adap) adap->getclock(adap->data) 51 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val) 52 #define i2c_inb(adap) adap->getpcf(adap->data, 0) 53 54 /* other auxiliary functions */ 55 56 static void i2c_start(struct i2c_algo_pcf_data *adap) 57 { 58 DEBPROTO(printk(KERN_DEBUG "S ")); 59 set_pcf(adap, 1, I2C_PCF_START); 60 } 61 62 static void i2c_repstart(struct i2c_algo_pcf_data *adap) 63 { 64 DEBPROTO(printk(" Sr ")); 65 set_pcf(adap, 1, I2C_PCF_REPSTART); 66 } 67 68 static void i2c_stop(struct i2c_algo_pcf_data *adap) 69 { 70 DEBPROTO(printk("P\n")); 71 set_pcf(adap, 1, I2C_PCF_STOP); 72 } 73 74 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status) 75 { 76 DEB2(printk(KERN_INFO 77 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n", 78 *status)); 79 /* 80 * Cleanup from LAB -- reset and enable ESO. 81 * This resets the PCF8584; since we've lost the bus, no 82 * further attempts should be made by callers to clean up 83 * (no i2c_stop() etc.) 84 */ 85 set_pcf(adap, 1, I2C_PCF_PIN); 86 set_pcf(adap, 1, I2C_PCF_ESO); 87 /* 88 * We pause for a time period sufficient for any running 89 * I2C transaction to complete -- the arbitration logic won't 90 * work properly until the next START is seen. 91 * It is assumed the bus driver or client has set a proper value. 92 * 93 * REVISIT: should probably use msleep instead of mdelay if we 94 * know we can sleep. 95 */ 96 if (adap->lab_mdelay) 97 mdelay(adap->lab_mdelay); 98 99 DEB2(printk(KERN_INFO 100 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n", 101 get_pcf(adap, 1))); 102 } 103 104 static int wait_for_bb(struct i2c_algo_pcf_data *adap) 105 { 106 107 int timeout = DEF_TIMEOUT; 108 int status; 109 110 status = get_pcf(adap, 1); 111 112 while (!(status & I2C_PCF_BB) && --timeout) { 113 udelay(100); /* wait for 100 us */ 114 status = get_pcf(adap, 1); 115 } 116 117 if (timeout == 0) { 118 printk(KERN_ERR "Timeout waiting for Bus Busy\n"); 119 return -ETIMEDOUT; 120 } 121 122 return 0; 123 } 124 125 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) 126 { 127 128 int timeout = DEF_TIMEOUT; 129 130 *status = get_pcf(adap, 1); 131 132 while ((*status & I2C_PCF_PIN) && --timeout) { 133 adap->waitforpin(adap->data); 134 *status = get_pcf(adap, 1); 135 } 136 if (*status & I2C_PCF_LAB) { 137 handle_lab(adap, status); 138 return -EINTR; 139 } 140 141 if (timeout == 0) 142 return -ETIMEDOUT; 143 144 return 0; 145 } 146 147 /* 148 * This should perform the 'PCF8584 initialization sequence' as described 149 * in the Philips IC12 data book (1995, Aug 29). 150 * There should be a 30 clock cycle wait after reset, I assume this 151 * has been fulfilled. 152 * There should be a delay at the end equal to the longest I2C message 153 * to synchronize the BB-bit (in multimaster systems). How long is 154 * this? I assume 1 second is always long enough. 155 * 156 * vdovikin: added detect code for PCF8584 157 */ 158 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap) 159 { 160 unsigned char temp; 161 162 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n", 163 get_pcf(adap, 1))); 164 165 /* S1=0x80: S0 selected, serial interface off */ 166 set_pcf(adap, 1, I2C_PCF_PIN); 167 /* 168 * check to see S1 now used as R/W ctrl - 169 * PCF8584 does that when ESO is zero 170 */ 171 if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) { 172 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp)); 173 return -ENXIO; /* definitely not PCF8584 */ 174 } 175 176 /* load own address in S0, effective address is (own << 1) */ 177 i2c_outb(adap, get_own(adap)); 178 /* check it's really written */ 179 if ((temp = i2c_inb(adap)) != get_own(adap)) { 180 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp)); 181 return -ENXIO; 182 } 183 184 /* S1=0xA0, next byte in S2 */ 185 set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1); 186 /* check to see S2 now selected */ 187 if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) { 188 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp)); 189 return -ENXIO; 190 } 191 192 /* load clock register S2 */ 193 i2c_outb(adap, get_clock(adap)); 194 /* check it's really written, the only 5 lowest bits does matter */ 195 if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) { 196 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp)); 197 return -ENXIO; 198 } 199 200 /* Enable serial interface, idle, S0 selected */ 201 set_pcf(adap, 1, I2C_PCF_IDLE); 202 203 /* check to see PCF is really idled and we can access status register */ 204 if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) { 205 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp)); 206 return -ENXIO; 207 } 208 209 printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n"); 210 211 return 0; 212 } 213 214 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf, 215 int count, int last) 216 { 217 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; 218 int wrcount, status, timeout; 219 220 for (wrcount=0; wrcount<count; ++wrcount) { 221 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n", 222 buf[wrcount] & 0xff)); 223 i2c_outb(adap, buf[wrcount]); 224 timeout = wait_for_pin(adap, &status); 225 if (timeout) { 226 if (timeout == -EINTR) 227 return -EINTR; /* arbitration lost */ 228 229 i2c_stop(adap); 230 dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n"); 231 return -EREMOTEIO; /* got a better one ?? */ 232 } 233 if (status & I2C_PCF_LRB) { 234 i2c_stop(adap); 235 dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n"); 236 return -EREMOTEIO; /* got a better one ?? */ 237 } 238 } 239 if (last) 240 i2c_stop(adap); 241 else 242 i2c_repstart(adap); 243 244 return wrcount; 245 } 246 247 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf, 248 int count, int last) 249 { 250 int i, status; 251 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; 252 int wfp; 253 254 /* increment number of bytes to read by one -- read dummy byte */ 255 for (i = 0; i <= count; i++) { 256 257 if ((wfp = wait_for_pin(adap, &status))) { 258 if (wfp == -EINTR) 259 return -EINTR; /* arbitration lost */ 260 261 i2c_stop(adap); 262 dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n"); 263 return -1; 264 } 265 266 if ((status & I2C_PCF_LRB) && (i != count)) { 267 i2c_stop(adap); 268 dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n"); 269 return -1; 270 } 271 272 if (i == count - 1) { 273 set_pcf(adap, 1, I2C_PCF_ESO); 274 } else if (i == count) { 275 if (last) 276 i2c_stop(adap); 277 else 278 i2c_repstart(adap); 279 } 280 281 if (i) 282 buf[i - 1] = i2c_inb(adap); 283 else 284 i2c_inb(adap); /* dummy read */ 285 } 286 287 return i - 1; 288 } 289 290 291 static int pcf_doAddress(struct i2c_algo_pcf_data *adap, 292 struct i2c_msg *msg) 293 { 294 unsigned char addr = i2c_8bit_addr_from_msg(msg); 295 296 if (msg->flags & I2C_M_REV_DIR_ADDR) 297 addr ^= 1; 298 i2c_outb(adap, addr); 299 300 return 0; 301 } 302 303 static int pcf_xfer(struct i2c_adapter *i2c_adap, 304 struct i2c_msg *msgs, 305 int num) 306 { 307 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; 308 struct i2c_msg *pmsg; 309 int i; 310 int ret=0, timeout, status; 311 312 if (adap->xfer_begin) 313 adap->xfer_begin(adap->data); 314 315 /* Check for bus busy */ 316 timeout = wait_for_bb(adap); 317 if (timeout) { 318 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: " 319 "Timeout waiting for BB in pcf_xfer\n");) 320 i = -EIO; 321 goto out; 322 } 323 324 for (i = 0;ret >= 0 && i < num; i++) { 325 pmsg = &msgs[i]; 326 327 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n", 328 pmsg->flags & I2C_M_RD ? "read" : "write", 329 pmsg->len, pmsg->addr, i + 1, num);) 330 331 ret = pcf_doAddress(adap, pmsg); 332 333 /* Send START */ 334 if (i == 0) 335 i2c_start(adap); 336 337 /* Wait for PIN (pending interrupt NOT) */ 338 timeout = wait_for_pin(adap, &status); 339 if (timeout) { 340 if (timeout == -EINTR) { 341 /* arbitration lost */ 342 i = -EINTR; 343 goto out; 344 } 345 i2c_stop(adap); 346 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting " 347 "for PIN(1) in pcf_xfer\n");) 348 i = -EREMOTEIO; 349 goto out; 350 } 351 352 /* Check LRB (last rcvd bit - slave ack) */ 353 if (status & I2C_PCF_LRB) { 354 i2c_stop(adap); 355 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");) 356 i = -EREMOTEIO; 357 goto out; 358 } 359 360 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n", 361 i, msgs[i].addr, msgs[i].flags, msgs[i].len);) 362 363 if (pmsg->flags & I2C_M_RD) { 364 ret = pcf_readbytes(i2c_adap, pmsg->buf, pmsg->len, 365 (i + 1 == num)); 366 367 if (ret != pmsg->len) { 368 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: " 369 "only read %d bytes.\n",ret)); 370 } else { 371 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret)); 372 } 373 } else { 374 ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len, 375 (i + 1 == num)); 376 377 if (ret != pmsg->len) { 378 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: " 379 "only wrote %d bytes.\n",ret)); 380 } else { 381 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret)); 382 } 383 } 384 } 385 386 out: 387 if (adap->xfer_end) 388 adap->xfer_end(adap->data); 389 return i; 390 } 391 392 static u32 pcf_func(struct i2c_adapter *adap) 393 { 394 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 395 I2C_FUNC_PROTOCOL_MANGLING; 396 } 397 398 /* exported algorithm data: */ 399 static const struct i2c_algorithm pcf_algo = { 400 .master_xfer = pcf_xfer, 401 .functionality = pcf_func, 402 }; 403 404 /* 405 * registering functions to load algorithms at runtime 406 */ 407 int i2c_pcf_add_bus(struct i2c_adapter *adap) 408 { 409 struct i2c_algo_pcf_data *pcf_adap = adap->algo_data; 410 int rval; 411 412 DEB2(dev_dbg(&adap->dev, "hw routines registered.\n")); 413 414 /* register new adapter to i2c module... */ 415 adap->algo = &pcf_algo; 416 417 if ((rval = pcf_init_8584(pcf_adap))) 418 return rval; 419 420 rval = i2c_add_adapter(adap); 421 422 return rval; 423 } 424 EXPORT_SYMBOL(i2c_pcf_add_bus); 425 426 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>"); 427 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm"); 428 MODULE_LICENSE("GPL"); 429 430 module_param(i2c_debug, int, S_IRUGO | S_IWUSR); 431 MODULE_PARM_DESC(i2c_debug, 432 "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol"); 433