1 /** 2 * ds2482.c - provides i2c to w1-master bridge(s) 3 * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com> 4 * 5 * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim). 6 * It is a I2C to 1-wire bridge. 7 * There are two variations: -100 and -800, which have 1 or 8 1-wire ports. 8 * The complete datasheet can be obtained from MAXIM's website at: 9 * http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382 10 * 11 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License as published by 13 * the Free Software Foundation; version 2 of the License. 14 */ 15 16 #include <linux/module.h> 17 #include <linux/init.h> 18 #include <linux/slab.h> 19 #include <linux/i2c.h> 20 #include <linux/delay.h> 21 #include <asm/delay.h> 22 23 #include "../w1.h" 24 #include "../w1_int.h" 25 26 /** 27 * The DS2482 registers - there are 3 registers that are addressed by a read 28 * pointer. The read pointer is set by the last command executed. 29 * 30 * To read the data, issue a register read for any address 31 */ 32 #define DS2482_CMD_RESET 0xF0 /* No param */ 33 #define DS2482_CMD_SET_READ_PTR 0xE1 /* Param: DS2482_PTR_CODE_xxx */ 34 #define DS2482_CMD_CHANNEL_SELECT 0xC3 /* Param: Channel byte - DS2482-800 only */ 35 #define DS2482_CMD_WRITE_CONFIG 0xD2 /* Param: Config byte */ 36 #define DS2482_CMD_1WIRE_RESET 0xB4 /* Param: None */ 37 #define DS2482_CMD_1WIRE_SINGLE_BIT 0x87 /* Param: Bit byte (bit7) */ 38 #define DS2482_CMD_1WIRE_WRITE_BYTE 0xA5 /* Param: Data byte */ 39 #define DS2482_CMD_1WIRE_READ_BYTE 0x96 /* Param: None */ 40 /* Note to read the byte, Set the ReadPtr to Data then read (any addr) */ 41 #define DS2482_CMD_1WIRE_TRIPLET 0x78 /* Param: Dir byte (bit7) */ 42 43 /* Values for DS2482_CMD_SET_READ_PTR */ 44 #define DS2482_PTR_CODE_STATUS 0xF0 45 #define DS2482_PTR_CODE_DATA 0xE1 46 #define DS2482_PTR_CODE_CHANNEL 0xD2 /* DS2482-800 only */ 47 #define DS2482_PTR_CODE_CONFIG 0xC3 48 49 /** 50 * Configure Register bit definitions 51 * The top 4 bits always read 0. 52 * To write, the top nibble must be the 1's compl. of the low nibble. 53 */ 54 #define DS2482_REG_CFG_1WS 0x08 /* 1-wire speed */ 55 #define DS2482_REG_CFG_SPU 0x04 /* strong pull-up */ 56 #define DS2482_REG_CFG_PPM 0x02 /* presence pulse masking */ 57 #define DS2482_REG_CFG_APU 0x01 /* active pull-up */ 58 59 60 /** 61 * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only). 62 * To set the channel, write the value at the index of the channel. 63 * Read and compare against the corresponding value to verify the change. 64 */ 65 static const u8 ds2482_chan_wr[8] = 66 { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 }; 67 static const u8 ds2482_chan_rd[8] = 68 { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 }; 69 70 71 /** 72 * Status Register bit definitions (read only) 73 */ 74 #define DS2482_REG_STS_DIR 0x80 75 #define DS2482_REG_STS_TSB 0x40 76 #define DS2482_REG_STS_SBR 0x20 77 #define DS2482_REG_STS_RST 0x10 78 #define DS2482_REG_STS_LL 0x08 79 #define DS2482_REG_STS_SD 0x04 80 #define DS2482_REG_STS_PPD 0x02 81 #define DS2482_REG_STS_1WB 0x01 82 83 84 static int ds2482_probe(struct i2c_client *client, 85 const struct i2c_device_id *id); 86 static int ds2482_remove(struct i2c_client *client); 87 88 89 /** 90 * Driver data (common to all clients) 91 */ 92 static const struct i2c_device_id ds2482_id[] = { 93 { "ds2482", 0 }, 94 { } 95 }; 96 MODULE_DEVICE_TABLE(i2c, ds2482_id); 97 98 static struct i2c_driver ds2482_driver = { 99 .driver = { 100 .name = "ds2482", 101 }, 102 .probe = ds2482_probe, 103 .remove = ds2482_remove, 104 .id_table = ds2482_id, 105 }; 106 107 /* 108 * Client data (each client gets its own) 109 */ 110 111 struct ds2482_data; 112 113 struct ds2482_w1_chan { 114 struct ds2482_data *pdev; 115 u8 channel; 116 struct w1_bus_master w1_bm; 117 }; 118 119 struct ds2482_data { 120 struct i2c_client *client; 121 struct mutex access_lock; 122 123 /* 1-wire interface(s) */ 124 int w1_count; /* 1 or 8 */ 125 struct ds2482_w1_chan w1_ch[8]; 126 127 /* per-device values */ 128 u8 channel; 129 u8 read_prt; /* see DS2482_PTR_CODE_xxx */ 130 u8 reg_config; 131 }; 132 133 134 /** 135 * Helper to calculate values for configuration register 136 * @param conf the raw config value 137 * @return the value w/ complements that can be written to register 138 */ 139 static inline u8 ds2482_calculate_config(u8 conf) 140 { 141 return conf | ((~conf & 0x0f) << 4); 142 } 143 144 145 /** 146 * Sets the read pointer. 147 * @param pdev The ds2482 client pointer 148 * @param read_ptr see DS2482_PTR_CODE_xxx above 149 * @return -1 on failure, 0 on success 150 */ 151 static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr) 152 { 153 if (pdev->read_prt != read_ptr) { 154 if (i2c_smbus_write_byte_data(pdev->client, 155 DS2482_CMD_SET_READ_PTR, 156 read_ptr) < 0) 157 return -1; 158 159 pdev->read_prt = read_ptr; 160 } 161 return 0; 162 } 163 164 /** 165 * Sends a command without a parameter 166 * @param pdev The ds2482 client pointer 167 * @param cmd DS2482_CMD_RESET, 168 * DS2482_CMD_1WIRE_RESET, 169 * DS2482_CMD_1WIRE_READ_BYTE 170 * @return -1 on failure, 0 on success 171 */ 172 static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd) 173 { 174 if (i2c_smbus_write_byte(pdev->client, cmd) < 0) 175 return -1; 176 177 pdev->read_prt = DS2482_PTR_CODE_STATUS; 178 return 0; 179 } 180 181 /** 182 * Sends a command with a parameter 183 * @param pdev The ds2482 client pointer 184 * @param cmd DS2482_CMD_WRITE_CONFIG, 185 * DS2482_CMD_1WIRE_SINGLE_BIT, 186 * DS2482_CMD_1WIRE_WRITE_BYTE, 187 * DS2482_CMD_1WIRE_TRIPLET 188 * @param byte The data to send 189 * @return -1 on failure, 0 on success 190 */ 191 static inline int ds2482_send_cmd_data(struct ds2482_data *pdev, 192 u8 cmd, u8 byte) 193 { 194 if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0) 195 return -1; 196 197 /* all cmds leave in STATUS, except CONFIG */ 198 pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ? 199 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG; 200 return 0; 201 } 202 203 204 /* 205 * 1-Wire interface code 206 */ 207 208 #define DS2482_WAIT_IDLE_TIMEOUT 100 209 210 /** 211 * Waits until the 1-wire interface is idle (not busy) 212 * 213 * @param pdev Pointer to the device structure 214 * @return the last value read from status or -1 (failure) 215 */ 216 static int ds2482_wait_1wire_idle(struct ds2482_data *pdev) 217 { 218 int temp = -1; 219 int retries = 0; 220 221 if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) { 222 do { 223 temp = i2c_smbus_read_byte(pdev->client); 224 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) && 225 (++retries < DS2482_WAIT_IDLE_TIMEOUT)); 226 } 227 228 if (retries >= DS2482_WAIT_IDLE_TIMEOUT) 229 pr_err("%s: timeout on channel %d\n", 230 __func__, pdev->channel); 231 232 return temp; 233 } 234 235 /** 236 * Selects a w1 channel. 237 * The 1-wire interface must be idle before calling this function. 238 * 239 * @param pdev The ds2482 client pointer 240 * @param channel 0-7 241 * @return -1 (failure) or 0 (success) 242 */ 243 static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel) 244 { 245 if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT, 246 ds2482_chan_wr[channel]) < 0) 247 return -1; 248 249 pdev->read_prt = DS2482_PTR_CODE_CHANNEL; 250 pdev->channel = -1; 251 if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) { 252 pdev->channel = channel; 253 return 0; 254 } 255 return -1; 256 } 257 258 259 /** 260 * Performs the touch-bit function, which writes a 0 or 1 and reads the level. 261 * 262 * @param data The ds2482 channel pointer 263 * @param bit The level to write: 0 or non-zero 264 * @return The level read: 0 or 1 265 */ 266 static u8 ds2482_w1_touch_bit(void *data, u8 bit) 267 { 268 struct ds2482_w1_chan *pchan = data; 269 struct ds2482_data *pdev = pchan->pdev; 270 int status = -1; 271 272 mutex_lock(&pdev->access_lock); 273 274 /* Select the channel */ 275 ds2482_wait_1wire_idle(pdev); 276 if (pdev->w1_count > 1) 277 ds2482_set_channel(pdev, pchan->channel); 278 279 /* Send the touch command, wait until 1WB == 0, return the status */ 280 if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT, 281 bit ? 0xFF : 0)) 282 status = ds2482_wait_1wire_idle(pdev); 283 284 mutex_unlock(&pdev->access_lock); 285 286 return (status & DS2482_REG_STS_SBR) ? 1 : 0; 287 } 288 289 /** 290 * Performs the triplet function, which reads two bits and writes a bit. 291 * The bit written is determined by the two reads: 292 * 00 => dbit, 01 => 0, 10 => 1 293 * 294 * @param data The ds2482 channel pointer 295 * @param dbit The direction to choose if both branches are valid 296 * @return b0=read1 b1=read2 b3=bit written 297 */ 298 static u8 ds2482_w1_triplet(void *data, u8 dbit) 299 { 300 struct ds2482_w1_chan *pchan = data; 301 struct ds2482_data *pdev = pchan->pdev; 302 int status = (3 << 5); 303 304 mutex_lock(&pdev->access_lock); 305 306 /* Select the channel */ 307 ds2482_wait_1wire_idle(pdev); 308 if (pdev->w1_count > 1) 309 ds2482_set_channel(pdev, pchan->channel); 310 311 /* Send the triplet command, wait until 1WB == 0, return the status */ 312 if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET, 313 dbit ? 0xFF : 0)) 314 status = ds2482_wait_1wire_idle(pdev); 315 316 mutex_unlock(&pdev->access_lock); 317 318 /* Decode the status */ 319 return (status >> 5); 320 } 321 322 /** 323 * Performs the write byte function. 324 * 325 * @param data The ds2482 channel pointer 326 * @param byte The value to write 327 */ 328 static void ds2482_w1_write_byte(void *data, u8 byte) 329 { 330 struct ds2482_w1_chan *pchan = data; 331 struct ds2482_data *pdev = pchan->pdev; 332 333 mutex_lock(&pdev->access_lock); 334 335 /* Select the channel */ 336 ds2482_wait_1wire_idle(pdev); 337 if (pdev->w1_count > 1) 338 ds2482_set_channel(pdev, pchan->channel); 339 340 /* Send the write byte command */ 341 ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte); 342 343 mutex_unlock(&pdev->access_lock); 344 } 345 346 /** 347 * Performs the read byte function. 348 * 349 * @param data The ds2482 channel pointer 350 * @return The value read 351 */ 352 static u8 ds2482_w1_read_byte(void *data) 353 { 354 struct ds2482_w1_chan *pchan = data; 355 struct ds2482_data *pdev = pchan->pdev; 356 int result; 357 358 mutex_lock(&pdev->access_lock); 359 360 /* Select the channel */ 361 ds2482_wait_1wire_idle(pdev); 362 if (pdev->w1_count > 1) 363 ds2482_set_channel(pdev, pchan->channel); 364 365 /* Send the read byte command */ 366 ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE); 367 368 /* Wait until 1WB == 0 */ 369 ds2482_wait_1wire_idle(pdev); 370 371 /* Select the data register */ 372 ds2482_select_register(pdev, DS2482_PTR_CODE_DATA); 373 374 /* Read the data byte */ 375 result = i2c_smbus_read_byte(pdev->client); 376 377 mutex_unlock(&pdev->access_lock); 378 379 return result; 380 } 381 382 383 /** 384 * Sends a reset on the 1-wire interface 385 * 386 * @param data The ds2482 channel pointer 387 * @return 0=Device present, 1=No device present or error 388 */ 389 static u8 ds2482_w1_reset_bus(void *data) 390 { 391 struct ds2482_w1_chan *pchan = data; 392 struct ds2482_data *pdev = pchan->pdev; 393 int err; 394 u8 retval = 1; 395 396 mutex_lock(&pdev->access_lock); 397 398 /* Select the channel */ 399 ds2482_wait_1wire_idle(pdev); 400 if (pdev->w1_count > 1) 401 ds2482_set_channel(pdev, pchan->channel); 402 403 /* Send the reset command */ 404 err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET); 405 if (err >= 0) { 406 /* Wait until the reset is complete */ 407 err = ds2482_wait_1wire_idle(pdev); 408 retval = !(err & DS2482_REG_STS_PPD); 409 410 /* If the chip did reset since detect, re-config it */ 411 if (err & DS2482_REG_STS_RST) 412 ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG, 413 ds2482_calculate_config(0x00)); 414 } 415 416 mutex_unlock(&pdev->access_lock); 417 418 return retval; 419 } 420 421 static u8 ds2482_w1_set_pullup(void *data, int delay) 422 { 423 struct ds2482_w1_chan *pchan = data; 424 struct ds2482_data *pdev = pchan->pdev; 425 u8 retval = 1; 426 427 /* if delay is non-zero activate the pullup, 428 * the strong pullup will be automatically deactivated 429 * by the master, so do not explicitly deactive it 430 */ 431 if (delay) { 432 /* both waits are crucial, otherwise devices might not be 433 * powered long enough, causing e.g. a w1_therm sensor to 434 * provide wrong conversion results 435 */ 436 ds2482_wait_1wire_idle(pdev); 437 /* note: it seems like both SPU and APU have to be set! */ 438 retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG, 439 ds2482_calculate_config(DS2482_REG_CFG_SPU | 440 DS2482_REG_CFG_APU)); 441 ds2482_wait_1wire_idle(pdev); 442 } 443 444 return retval; 445 } 446 447 448 static int ds2482_probe(struct i2c_client *client, 449 const struct i2c_device_id *id) 450 { 451 struct ds2482_data *data; 452 int err = -ENODEV; 453 int temp1; 454 int idx; 455 456 if (!i2c_check_functionality(client->adapter, 457 I2C_FUNC_SMBUS_WRITE_BYTE_DATA | 458 I2C_FUNC_SMBUS_BYTE)) 459 return -ENODEV; 460 461 if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) { 462 err = -ENOMEM; 463 goto exit; 464 } 465 466 data->client = client; 467 i2c_set_clientdata(client, data); 468 469 /* Reset the device (sets the read_ptr to status) */ 470 if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) { 471 dev_warn(&client->dev, "DS2482 reset failed.\n"); 472 goto exit_free; 473 } 474 475 /* Sleep at least 525ns to allow the reset to complete */ 476 ndelay(525); 477 478 /* Read the status byte - only reset bit and line should be set */ 479 temp1 = i2c_smbus_read_byte(client); 480 if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) { 481 dev_warn(&client->dev, "DS2482 reset status " 482 "0x%02X - not a DS2482\n", temp1); 483 goto exit_free; 484 } 485 486 /* Detect the 8-port version */ 487 data->w1_count = 1; 488 if (ds2482_set_channel(data, 7) == 0) 489 data->w1_count = 8; 490 491 /* Set all config items to 0 (off) */ 492 ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 493 ds2482_calculate_config(0x00)); 494 495 mutex_init(&data->access_lock); 496 497 /* Register 1-wire interface(s) */ 498 for (idx = 0; idx < data->w1_count; idx++) { 499 data->w1_ch[idx].pdev = data; 500 data->w1_ch[idx].channel = idx; 501 502 /* Populate all the w1 bus master stuff */ 503 data->w1_ch[idx].w1_bm.data = &data->w1_ch[idx]; 504 data->w1_ch[idx].w1_bm.read_byte = ds2482_w1_read_byte; 505 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte; 506 data->w1_ch[idx].w1_bm.touch_bit = ds2482_w1_touch_bit; 507 data->w1_ch[idx].w1_bm.triplet = ds2482_w1_triplet; 508 data->w1_ch[idx].w1_bm.reset_bus = ds2482_w1_reset_bus; 509 data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup; 510 511 err = w1_add_master_device(&data->w1_ch[idx].w1_bm); 512 if (err) { 513 data->w1_ch[idx].pdev = NULL; 514 goto exit_w1_remove; 515 } 516 } 517 518 return 0; 519 520 exit_w1_remove: 521 for (idx = 0; idx < data->w1_count; idx++) { 522 if (data->w1_ch[idx].pdev != NULL) 523 w1_remove_master_device(&data->w1_ch[idx].w1_bm); 524 } 525 exit_free: 526 kfree(data); 527 exit: 528 return err; 529 } 530 531 static int ds2482_remove(struct i2c_client *client) 532 { 533 struct ds2482_data *data = i2c_get_clientdata(client); 534 int idx; 535 536 /* Unregister the 1-wire bridge(s) */ 537 for (idx = 0; idx < data->w1_count; idx++) { 538 if (data->w1_ch[idx].pdev != NULL) 539 w1_remove_master_device(&data->w1_ch[idx].w1_bm); 540 } 541 542 /* Free the memory */ 543 kfree(data); 544 return 0; 545 } 546 547 module_i2c_driver(ds2482_driver); 548 549 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>"); 550 MODULE_DESCRIPTION("DS2482 driver"); 551 MODULE_LICENSE("GPL"); 552