drivers/w1/masters/ds2482.c

   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
  97 static struct i2c_driver ds2482_driver = {
  98         .driver = {
  99                 .owner  = THIS_MODULE,
 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                 printk(KERN_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");