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 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, 20 * MA 02110-1301 USA. 21 * 22 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and 23 * Frodo Looijaard <frodol@dds.nl>, and also from Martin Bailey 24 * <mbailey@littlefeet-inc.com> 25 * 26 * Partially rewriten by Oleg I. Vdovikin <vdovikin@jscc.ru> to handle multiple 27 * messages, proper stop/repstart signaling during receive, added detect code 28 */ 29 30 #include <linux/kernel.h> 31 #include <linux/module.h> 32 #include <linux/delay.h> 33 #include <linux/init.h> 34 #include <linux/errno.h> 35 #include <linux/i2c.h> 36 #include <linux/i2c-algo-pcf.h> 37 #include "i2c-algo-pcf.h" 38 39 40 #define DEB2(x) if (i2c_debug >= 2) x 41 #define DEB3(x) if (i2c_debug >= 3) x /* print several statistical values */ 42 #define DEBPROTO(x) if (i2c_debug >= 9) x; 43 /* debug the protocol by showing transferred bits */ 44 #define DEF_TIMEOUT 16 45 46 /* 47 * module parameters: 48 */ 49 static int i2c_debug; 50 51 /* setting states on the bus with the right timing: */ 52 53 #define set_pcf(adap, ctl, val) adap->setpcf(adap->data, ctl, val) 54 #define get_pcf(adap, ctl) adap->getpcf(adap->data, ctl) 55 #define get_own(adap) adap->getown(adap->data) 56 #define get_clock(adap) adap->getclock(adap->data) 57 #define i2c_outb(adap, val) adap->setpcf(adap->data, 0, val) 58 #define i2c_inb(adap) adap->getpcf(adap->data, 0) 59 60 /* other auxiliary functions */ 61 62 static void i2c_start(struct i2c_algo_pcf_data *adap) 63 { 64 DEBPROTO(printk(KERN_DEBUG "S ")); 65 set_pcf(adap, 1, I2C_PCF_START); 66 } 67 68 static void i2c_repstart(struct i2c_algo_pcf_data *adap) 69 { 70 DEBPROTO(printk(" Sr ")); 71 set_pcf(adap, 1, I2C_PCF_REPSTART); 72 } 73 74 static void i2c_stop(struct i2c_algo_pcf_data *adap) 75 { 76 DEBPROTO(printk("P\n")); 77 set_pcf(adap, 1, I2C_PCF_STOP); 78 } 79 80 static void handle_lab(struct i2c_algo_pcf_data *adap, const int *status) 81 { 82 DEB2(printk(KERN_INFO 83 "i2c-algo-pcf.o: lost arbitration (CSR 0x%02x)\n", 84 *status)); 85 /* 86 * Cleanup from LAB -- reset and enable ESO. 87 * This resets the PCF8584; since we've lost the bus, no 88 * further attempts should be made by callers to clean up 89 * (no i2c_stop() etc.) 90 */ 91 set_pcf(adap, 1, I2C_PCF_PIN); 92 set_pcf(adap, 1, I2C_PCF_ESO); 93 /* 94 * We pause for a time period sufficient for any running 95 * I2C transaction to complete -- the arbitration logic won't 96 * work properly until the next START is seen. 97 * It is assumed the bus driver or client has set a proper value. 98 * 99 * REVISIT: should probably use msleep instead of mdelay if we 100 * know we can sleep. 101 */ 102 if (adap->lab_mdelay) 103 mdelay(adap->lab_mdelay); 104 105 DEB2(printk(KERN_INFO 106 "i2c-algo-pcf.o: reset LAB condition (CSR 0x%02x)\n", 107 get_pcf(adap, 1))); 108 } 109 110 static int wait_for_bb(struct i2c_algo_pcf_data *adap) 111 { 112 113 int timeout = DEF_TIMEOUT; 114 int status; 115 116 status = get_pcf(adap, 1); 117 118 while (!(status & I2C_PCF_BB) && --timeout) { 119 udelay(100); /* wait for 100 us */ 120 status = get_pcf(adap, 1); 121 } 122 123 if (timeout == 0) { 124 printk(KERN_ERR "Timeout waiting for Bus Busy\n"); 125 return -ETIMEDOUT; 126 } 127 128 return 0; 129 } 130 131 static int wait_for_pin(struct i2c_algo_pcf_data *adap, int *status) 132 { 133 134 int timeout = DEF_TIMEOUT; 135 136 *status = get_pcf(adap, 1); 137 138 while ((*status & I2C_PCF_PIN) && --timeout) { 139 adap->waitforpin(adap->data); 140 *status = get_pcf(adap, 1); 141 } 142 if (*status & I2C_PCF_LAB) { 143 handle_lab(adap, status); 144 return -EINTR; 145 } 146 147 if (timeout == 0) 148 return -ETIMEDOUT; 149 150 return 0; 151 } 152 153 /* 154 * This should perform the 'PCF8584 initialization sequence' as described 155 * in the Philips IC12 data book (1995, Aug 29). 156 * There should be a 30 clock cycle wait after reset, I assume this 157 * has been fulfilled. 158 * There should be a delay at the end equal to the longest I2C message 159 * to synchronize the BB-bit (in multimaster systems). How long is 160 * this? I assume 1 second is always long enough. 161 * 162 * vdovikin: added detect code for PCF8584 163 */ 164 static int pcf_init_8584 (struct i2c_algo_pcf_data *adap) 165 { 166 unsigned char temp; 167 168 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: PCF state 0x%02x\n", 169 get_pcf(adap, 1))); 170 171 /* S1=0x80: S0 selected, serial interface off */ 172 set_pcf(adap, 1, I2C_PCF_PIN); 173 /* 174 * check to see S1 now used as R/W ctrl - 175 * PCF8584 does that when ESO is zero 176 */ 177 if (((temp = get_pcf(adap, 1)) & 0x7f) != (0)) { 178 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S0 (0x%02x).\n", temp)); 179 return -ENXIO; /* definitely not PCF8584 */ 180 } 181 182 /* load own address in S0, effective address is (own << 1) */ 183 i2c_outb(adap, get_own(adap)); 184 /* check it's really written */ 185 if ((temp = i2c_inb(adap)) != get_own(adap)) { 186 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S0 (0x%02x).\n", temp)); 187 return -ENXIO; 188 } 189 190 /* S1=0xA0, next byte in S2 */ 191 set_pcf(adap, 1, I2C_PCF_PIN | I2C_PCF_ES1); 192 /* check to see S2 now selected */ 193 if (((temp = get_pcf(adap, 1)) & 0x7f) != I2C_PCF_ES1) { 194 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S2 (0x%02x).\n", temp)); 195 return -ENXIO; 196 } 197 198 /* load clock register S2 */ 199 i2c_outb(adap, get_clock(adap)); 200 /* check it's really written, the only 5 lowest bits does matter */ 201 if (((temp = i2c_inb(adap)) & 0x1f) != get_clock(adap)) { 202 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't set S2 (0x%02x).\n", temp)); 203 return -ENXIO; 204 } 205 206 /* Enable serial interface, idle, S0 selected */ 207 set_pcf(adap, 1, I2C_PCF_IDLE); 208 209 /* check to see PCF is really idled and we can access status register */ 210 if ((temp = get_pcf(adap, 1)) != (I2C_PCF_PIN | I2C_PCF_BB)) { 211 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: PCF detection failed -- can't select S1` (0x%02x).\n", temp)); 212 return -ENXIO; 213 } 214 215 printk(KERN_DEBUG "i2c-algo-pcf.o: detected and initialized PCF8584.\n"); 216 217 return 0; 218 } 219 220 static int pcf_sendbytes(struct i2c_adapter *i2c_adap, const char *buf, 221 int count, int last) 222 { 223 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; 224 int wrcount, status, timeout; 225 226 for (wrcount=0; wrcount<count; ++wrcount) { 227 DEB2(dev_dbg(&i2c_adap->dev, "i2c_write: writing %2.2X\n", 228 buf[wrcount] & 0xff)); 229 i2c_outb(adap, buf[wrcount]); 230 timeout = wait_for_pin(adap, &status); 231 if (timeout) { 232 if (timeout == -EINTR) 233 return -EINTR; /* arbitration lost */ 234 235 i2c_stop(adap); 236 dev_err(&i2c_adap->dev, "i2c_write: error - timeout.\n"); 237 return -EREMOTEIO; /* got a better one ?? */ 238 } 239 if (status & I2C_PCF_LRB) { 240 i2c_stop(adap); 241 dev_err(&i2c_adap->dev, "i2c_write: error - no ack.\n"); 242 return -EREMOTEIO; /* got a better one ?? */ 243 } 244 } 245 if (last) 246 i2c_stop(adap); 247 else 248 i2c_repstart(adap); 249 250 return wrcount; 251 } 252 253 static int pcf_readbytes(struct i2c_adapter *i2c_adap, char *buf, 254 int count, int last) 255 { 256 int i, status; 257 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; 258 int wfp; 259 260 /* increment number of bytes to read by one -- read dummy byte */ 261 for (i = 0; i <= count; i++) { 262 263 if ((wfp = wait_for_pin(adap, &status))) { 264 if (wfp == -EINTR) 265 return -EINTR; /* arbitration lost */ 266 267 i2c_stop(adap); 268 dev_err(&i2c_adap->dev, "pcf_readbytes timed out.\n"); 269 return -1; 270 } 271 272 if ((status & I2C_PCF_LRB) && (i != count)) { 273 i2c_stop(adap); 274 dev_err(&i2c_adap->dev, "i2c_read: i2c_inb, No ack.\n"); 275 return -1; 276 } 277 278 if (i == count - 1) { 279 set_pcf(adap, 1, I2C_PCF_ESO); 280 } else if (i == count) { 281 if (last) 282 i2c_stop(adap); 283 else 284 i2c_repstart(adap); 285 } 286 287 if (i) 288 buf[i - 1] = i2c_inb(adap); 289 else 290 i2c_inb(adap); /* dummy read */ 291 } 292 293 return i - 1; 294 } 295 296 297 static int pcf_doAddress(struct i2c_algo_pcf_data *adap, 298 struct i2c_msg *msg) 299 { 300 unsigned short flags = msg->flags; 301 unsigned char addr; 302 303 addr = msg->addr << 1; 304 if (flags & I2C_M_RD) 305 addr |= 1; 306 if (flags & I2C_M_REV_DIR_ADDR) 307 addr ^= 1; 308 i2c_outb(adap, addr); 309 310 return 0; 311 } 312 313 static int pcf_xfer(struct i2c_adapter *i2c_adap, 314 struct i2c_msg *msgs, 315 int num) 316 { 317 struct i2c_algo_pcf_data *adap = i2c_adap->algo_data; 318 struct i2c_msg *pmsg; 319 int i; 320 int ret=0, timeout, status; 321 322 if (adap->xfer_begin) 323 adap->xfer_begin(adap->data); 324 325 /* Check for bus busy */ 326 timeout = wait_for_bb(adap); 327 if (timeout) { 328 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: " 329 "Timeout waiting for BB in pcf_xfer\n");) 330 i = -EIO; 331 goto out; 332 } 333 334 for (i = 0;ret >= 0 && i < num; i++) { 335 pmsg = &msgs[i]; 336 337 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: Doing %s %d bytes to 0x%02x - %d of %d messages\n", 338 pmsg->flags & I2C_M_RD ? "read" : "write", 339 pmsg->len, pmsg->addr, i + 1, num);) 340 341 ret = pcf_doAddress(adap, pmsg); 342 343 /* Send START */ 344 if (i == 0) 345 i2c_start(adap); 346 347 /* Wait for PIN (pending interrupt NOT) */ 348 timeout = wait_for_pin(adap, &status); 349 if (timeout) { 350 if (timeout == -EINTR) { 351 /* arbitration lost */ 352 i = -EINTR; 353 goto out; 354 } 355 i2c_stop(adap); 356 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: Timeout waiting " 357 "for PIN(1) in pcf_xfer\n");) 358 i = -EREMOTEIO; 359 goto out; 360 } 361 362 /* Check LRB (last rcvd bit - slave ack) */ 363 if (status & I2C_PCF_LRB) { 364 i2c_stop(adap); 365 DEB2(printk(KERN_ERR "i2c-algo-pcf.o: No LRB(1) in pcf_xfer\n");) 366 i = -EREMOTEIO; 367 goto out; 368 } 369 370 DEB3(printk(KERN_DEBUG "i2c-algo-pcf.o: Msg %d, addr=0x%x, flags=0x%x, len=%d\n", 371 i, msgs[i].addr, msgs[i].flags, msgs[i].len);) 372 373 if (pmsg->flags & I2C_M_RD) { 374 ret = pcf_readbytes(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 read %d bytes.\n",ret)); 380 } else { 381 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: read %d bytes.\n",ret)); 382 } 383 } else { 384 ret = pcf_sendbytes(i2c_adap, pmsg->buf, pmsg->len, 385 (i + 1 == num)); 386 387 if (ret != pmsg->len) { 388 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: fail: " 389 "only wrote %d bytes.\n",ret)); 390 } else { 391 DEB2(printk(KERN_DEBUG "i2c-algo-pcf.o: wrote %d bytes.\n",ret)); 392 } 393 } 394 } 395 396 out: 397 if (adap->xfer_end) 398 adap->xfer_end(adap->data); 399 return i; 400 } 401 402 static u32 pcf_func(struct i2c_adapter *adap) 403 { 404 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 405 I2C_FUNC_PROTOCOL_MANGLING; 406 } 407 408 /* exported algorithm data: */ 409 static const struct i2c_algorithm pcf_algo = { 410 .master_xfer = pcf_xfer, 411 .functionality = pcf_func, 412 }; 413 414 /* 415 * registering functions to load algorithms at runtime 416 */ 417 int i2c_pcf_add_bus(struct i2c_adapter *adap) 418 { 419 struct i2c_algo_pcf_data *pcf_adap = adap->algo_data; 420 int rval; 421 422 DEB2(dev_dbg(&adap->dev, "hw routines registered.\n")); 423 424 /* register new adapter to i2c module... */ 425 adap->algo = &pcf_algo; 426 427 if ((rval = pcf_init_8584(pcf_adap))) 428 return rval; 429 430 rval = i2c_add_adapter(adap); 431 432 return rval; 433 } 434 EXPORT_SYMBOL(i2c_pcf_add_bus); 435 436 MODULE_AUTHOR("Hans Berglund <hb@spacetec.no>"); 437 MODULE_DESCRIPTION("I2C-Bus PCF8584 algorithm"); 438 MODULE_LICENSE("GPL"); 439 440 module_param(i2c_debug, int, S_IRUGO | S_IWUSR); 441 MODULE_PARM_DESC(i2c_debug, 442 "debug level - 0 off; 1 normal; 2,3 more verbose; 9 pcf-protocol"); 443