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 MODULE_DEVICE_TABLE(i2c, ds2482_id);
  97
  98 static struct i2c_driver ds2482_driver = {
  99         .driver = {
 100                 .owner  = THIS_MODULE,
 101                 .name   = "ds2482",
 102         },
 103         .probe          = ds2482_probe,
 104         .remove         = ds2482_remove,
 105         .id_table       = ds2482_id,
 106 };
 107
 108 /*
 109  * Client data (each client gets its own)
 110  */
 111
 112 struct ds2482_data;
 113
 114 struct ds2482_w1_chan {
 115         struct ds2482_data      *pdev;
 116         u8                      channel;
 117         struct w1_bus_master    w1_bm;
 118 };
 119
 120 struct ds2482_data {
 121         struct i2c_client       *client;
 122         struct mutex            access_lock;
 123
 124         /* 1-wire interface(s) */
 125         int                     w1_count;       /* 1 or 8 */
 126         struct ds2482_w1_chan   w1_ch[8];
 127
 128         /* per-device values */
 129         u8                      channel;
 130         u8                      read_prt;       /* see DS2482_PTR_CODE_xxx */
 131         u8                      reg_config;
 132 };
 133
 134
 135 /**
 136  * Helper to calculate values for configuration register
 137  * @param conf the raw config value
 138  * @return the value w/ complements that can be written to register
 139  */
 140 static inline u8 ds2482_calculate_config(u8 conf)
 141 {
 142         return conf | ((~conf & 0x0f) << 4);
 143 }
 144
 145
 146 /**
 147  * Sets the read pointer.
 148  * @param pdev          The ds2482 client pointer
 149  * @param read_ptr      see DS2482_PTR_CODE_xxx above
 150  * @return -1 on failure, 0 on success
 151  */
 152 static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
 153 {
 154         if (pdev->read_prt != read_ptr) {
 155                 if (i2c_smbus_write_byte_data(pdev->client,
 156                                               DS2482_CMD_SET_READ_PTR,
 157                                               read_ptr) < 0)
 158                         return -1;
 159
 160                 pdev->read_prt = read_ptr;
 161         }
 162         return 0;
 163 }
 164
 165 /**
 166  * Sends a command without a parameter
 167  * @param pdev  The ds2482 client pointer
 168  * @param cmd   DS2482_CMD_RESET,
 169  *              DS2482_CMD_1WIRE_RESET,
 170  *              DS2482_CMD_1WIRE_READ_BYTE
 171  * @return -1 on failure, 0 on success
 172  */
 173 static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
 174 {
 175         if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
 176                 return -1;
 177
 178         pdev->read_prt = DS2482_PTR_CODE_STATUS;
 179         return 0;
 180 }
 181
 182 /**
 183  * Sends a command with a parameter
 184  * @param pdev  The ds2482 client pointer
 185  * @param cmd   DS2482_CMD_WRITE_CONFIG,
 186  *              DS2482_CMD_1WIRE_SINGLE_BIT,
 187  *              DS2482_CMD_1WIRE_WRITE_BYTE,
 188  *              DS2482_CMD_1WIRE_TRIPLET
 189  * @param byte  The data to send
 190  * @return -1 on failure, 0 on success
 191  */
 192 static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
 193                                        u8 cmd, u8 byte)
 194 {
 195         if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
 196                 return -1;
 197
 198         /* all cmds leave in STATUS, except CONFIG */
 199         pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
 200                          DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
 201         return 0;
 202 }
 203
 204
 205 /*
 206  * 1-Wire interface code
 207  */
 208
 209 #define DS2482_WAIT_IDLE_TIMEOUT        100
 210
 211 /**
 212  * Waits until the 1-wire interface is idle (not busy)
 213  *
 214  * @param pdev Pointer to the device structure
 215  * @return the last value read from status or -1 (failure)
 216  */
 217 static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
 218 {
 219         int temp = -1;
 220         int retries = 0;
 221
 222         if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
 223                 do {
 224                         temp = i2c_smbus_read_byte(pdev->client);
 225                 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
 226                          (++retries < DS2482_WAIT_IDLE_TIMEOUT));
 227         }
 228
 229         if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
 230                 pr_err("%s: timeout on channel %d\n",
 231                        __func__, pdev->channel);
 232
 233         return temp;
 234 }
 235
 236 /**
 237  * Selects a w1 channel.
 238  * The 1-wire interface must be idle before calling this function.
 239  *
 240  * @param pdev          The ds2482 client pointer
 241  * @param channel       0-7
 242  * @return              -1 (failure) or 0 (success)
 243  */
 244 static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
 245 {
 246         if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
 247                                       ds2482_chan_wr[channel]) < 0)
 248                 return -1;
 249
 250         pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
 251         pdev->channel = -1;
 252         if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
 253                 pdev->channel = channel;
 254                 return 0;
 255         }
 256         return -1;
 257 }
 258
 259
 260 /**
 261  * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
 262  *
 263  * @param data  The ds2482 channel pointer
 264  * @param bit   The level to write: 0 or non-zero
 265  * @return      The level read: 0 or 1
 266  */
 267 static u8 ds2482_w1_touch_bit(void *data, u8 bit)
 268 {
 269         struct ds2482_w1_chan *pchan = data;
 270         struct ds2482_data    *pdev = pchan->pdev;
 271         int status = -1;
 272
 273         mutex_lock(&pdev->access_lock);
 274
 275         /* Select the channel */
 276         ds2482_wait_1wire_idle(pdev);
 277         if (pdev->w1_count > 1)
 278                 ds2482_set_channel(pdev, pchan->channel);
 279
 280         /* Send the touch command, wait until 1WB == 0, return the status */
 281         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
 282                                   bit ? 0xFF : 0))
 283                 status = ds2482_wait_1wire_idle(pdev);
 284
 285         mutex_unlock(&pdev->access_lock);
 286
 287         return (status & DS2482_REG_STS_SBR) ? 1 : 0;
 288 }
 289
 290 /**
 291  * Performs the triplet function, which reads two bits and writes a bit.
 292  * The bit written is determined by the two reads:
 293  *   00 => dbit, 01 => 0, 10 => 1
 294  *
 295  * @param data  The ds2482 channel pointer
 296  * @param dbit  The direction to choose if both branches are valid
 297  * @return      b0=read1 b1=read2 b3=bit written
 298  */
 299 static u8 ds2482_w1_triplet(void *data, u8 dbit)
 300 {
 301         struct ds2482_w1_chan *pchan = data;
 302         struct ds2482_data    *pdev = pchan->pdev;
 303         int status = (3 << 5);
 304
 305         mutex_lock(&pdev->access_lock);
 306
 307         /* Select the channel */
 308         ds2482_wait_1wire_idle(pdev);
 309         if (pdev->w1_count > 1)
 310                 ds2482_set_channel(pdev, pchan->channel);
 311
 312         /* Send the triplet command, wait until 1WB == 0, return the status */
 313         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
 314                                   dbit ? 0xFF : 0))
 315                 status = ds2482_wait_1wire_idle(pdev);
 316
 317         mutex_unlock(&pdev->access_lock);
 318
 319         /* Decode the status */
 320         return (status >> 5);
 321 }
 322
 323 /**
 324  * Performs the write byte function.
 325  *
 326  * @param data  The ds2482 channel pointer
 327  * @param byte  The value to write
 328  */
 329 static void ds2482_w1_write_byte(void *data, u8 byte)
 330 {
 331         struct ds2482_w1_chan *pchan = data;
 332         struct ds2482_data    *pdev = pchan->pdev;
 333
 334         mutex_lock(&pdev->access_lock);
 335
 336         /* Select the channel */
 337         ds2482_wait_1wire_idle(pdev);
 338         if (pdev->w1_count > 1)
 339                 ds2482_set_channel(pdev, pchan->channel);
 340
 341         /* Send the write byte command */
 342         ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
 343
 344         mutex_unlock(&pdev->access_lock);
 345 }
 346
 347 /**
 348  * Performs the read byte function.
 349  *
 350  * @param data  The ds2482 channel pointer
 351  * @return      The value read
 352  */
 353 static u8 ds2482_w1_read_byte(void *data)
 354 {
 355         struct ds2482_w1_chan *pchan = data;
 356         struct ds2482_data    *pdev = pchan->pdev;
 357         int result;
 358
 359         mutex_lock(&pdev->access_lock);
 360
 361         /* Select the channel */
 362         ds2482_wait_1wire_idle(pdev);
 363         if (pdev->w1_count > 1)
 364                 ds2482_set_channel(pdev, pchan->channel);
 365
 366         /* Send the read byte command */
 367         ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
 368
 369         /* Wait until 1WB == 0 */
 370         ds2482_wait_1wire_idle(pdev);
 371
 372         /* Select the data register */
 373         ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
 374
 375         /* Read the data byte */
 376         result = i2c_smbus_read_byte(pdev->client);
 377
 378         mutex_unlock(&pdev->access_lock);
 379
 380         return result;
 381 }
 382
 383
 384 /**
 385  * Sends a reset on the 1-wire interface
 386  *
 387  * @param data  The ds2482 channel pointer
 388  * @return      0=Device present, 1=No device present or error
 389  */
 390 static u8 ds2482_w1_reset_bus(void *data)
 391 {
 392         struct ds2482_w1_chan *pchan = data;
 393         struct ds2482_data    *pdev = pchan->pdev;
 394         int err;
 395         u8 retval = 1;
 396
 397         mutex_lock(&pdev->access_lock);
 398
 399         /* Select the channel */
 400         ds2482_wait_1wire_idle(pdev);
 401         if (pdev->w1_count > 1)
 402                 ds2482_set_channel(pdev, pchan->channel);
 403
 404         /* Send the reset command */
 405         err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
 406         if (err >= 0) {
 407                 /* Wait until the reset is complete */
 408                 err = ds2482_wait_1wire_idle(pdev);
 409                 retval = !(err & DS2482_REG_STS_PPD);
 410
 411                 /* If the chip did reset since detect, re-config it */
 412                 if (err & DS2482_REG_STS_RST)
 413                         ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 414                                              ds2482_calculate_config(0x00));
 415         }
 416
 417         mutex_unlock(&pdev->access_lock);
 418
 419         return retval;
 420 }
 421
 422 static u8 ds2482_w1_set_pullup(void *data, int delay)
 423 {
 424         struct ds2482_w1_chan *pchan = data;
 425         struct ds2482_data    *pdev = pchan->pdev;
 426         u8 retval = 1;
 427
 428         /* if delay is non-zero activate the pullup,
 429          * the strong pullup will be automatically deactivated
 430          * by the master, so do not explicitly deactive it
 431          */
 432         if (delay) {
 433                 /* both waits are crucial, otherwise devices might not be
 434                  * powered long enough, causing e.g. a w1_therm sensor to
 435                  * provide wrong conversion results
 436                  */
 437                 ds2482_wait_1wire_idle(pdev);
 438                 /* note: it seems like both SPU and APU have to be set! */
 439                 retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 440                         ds2482_calculate_config(DS2482_REG_CFG_SPU |
 441                                                 DS2482_REG_CFG_APU));
 442                 ds2482_wait_1wire_idle(pdev);
 443         }
 444
 445         return retval;
 446 }
 447
 448
 449 static int ds2482_probe(struct i2c_client *client,
 450                         const struct i2c_device_id *id)
 451 {
 452         struct ds2482_data *data;
 453         int err = -ENODEV;
 454         int temp1;
 455         int idx;
 456
 457         if (!i2c_check_functionality(client->adapter,
 458                                      I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
 459                                      I2C_FUNC_SMBUS_BYTE))
 460                 return -ENODEV;
 461
 462         if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
 463                 err = -ENOMEM;
 464                 goto exit;
 465         }
 466
 467         data->client = client;
 468         i2c_set_clientdata(client, data);
 469
 470         /* Reset the device (sets the read_ptr to status) */
 471         if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
 472                 dev_warn(&client->dev, "DS2482 reset failed.\n");
 473                 goto exit_free;
 474         }
 475
 476         /* Sleep at least 525ns to allow the reset to complete */
 477         ndelay(525);
 478
 479         /* Read the status byte - only reset bit and line should be set */
 480         temp1 = i2c_smbus_read_byte(client);
 481         if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
 482                 dev_warn(&client->dev, "DS2482 reset status "
 483                          "0x%02X - not a DS2482\n", temp1);
 484                 goto exit_free;
 485         }
 486
 487         /* Detect the 8-port version */
 488         data->w1_count = 1;
 489         if (ds2482_set_channel(data, 7) == 0)
 490                 data->w1_count = 8;
 491
 492         /* Set all config items to 0 (off) */
 493         ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
 494                 ds2482_calculate_config(0x00));
 495
 496         mutex_init(&data->access_lock);
 497
 498         /* Register 1-wire interface(s) */
 499         for (idx = 0; idx < data->w1_count; idx++) {
 500                 data->w1_ch[idx].pdev = data;
 501                 data->w1_ch[idx].channel = idx;
 502
 503                 /* Populate all the w1 bus master stuff */
 504                 data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
 505                 data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
 506                 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
 507                 data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
 508                 data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
 509                 data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
 510                 data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
 511
 512                 err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
 513                 if (err) {
 514                         data->w1_ch[idx].pdev = NULL;
 515                         goto exit_w1_remove;
 516                 }
 517         }
 518
 519         return 0;
 520
 521 exit_w1_remove:
 522         for (idx = 0; idx < data->w1_count; idx++) {
 523                 if (data->w1_ch[idx].pdev != NULL)
 524                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 525         }
 526 exit_free:
 527         kfree(data);
 528 exit:
 529         return err;
 530 }
 531
 532 static int ds2482_remove(struct i2c_client *client)
 533 {
 534         struct ds2482_data   *data = i2c_get_clientdata(client);
 535         int idx;
 536
 537         /* Unregister the 1-wire bridge(s) */
 538         for (idx = 0; idx < data->w1_count; idx++) {
 539                 if (data->w1_ch[idx].pdev != NULL)
 540                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 541         }
 542
 543         /* Free the memory */
 544         kfree(data);
 545         return 0;
 546 }
 547
 548 module_i2c_driver(ds2482_driver);
 549
 550 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
 551 MODULE_DESCRIPTION("DS2482 driver");
 552 MODULE_LICENSE("GPL");