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); 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))) { 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, 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); 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, pmsg->buf, pmsg->len, 356 (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, pmsg->buf, pmsg->len, 366 (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(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