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
  55 #define DS2482_REG_CFG_SPU              0x04
  56 #define DS2482_REG_CFG_PPM              0x02
  57 #define DS2482_REG_CFG_APU              0x01
  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  * Sets the read pointer.
 136  * @param pdev          The ds2482 client pointer
 137  * @param read_ptr      see DS2482_PTR_CODE_xxx above
 138  * @return -1 on failure, 0 on success
 139  */
 140 static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
 141 {
 142         if (pdev->read_prt != read_ptr) {
 143                 if (i2c_smbus_write_byte_data(pdev->client,
 144                                               DS2482_CMD_SET_READ_PTR,
 145                                               read_ptr) < 0)
 146                         return -1;
 147
 148                 pdev->read_prt = read_ptr;
 149         }
 150         return 0;
 151 }
 152
 153 /**
 154  * Sends a command without a parameter
 155  * @param pdev  The ds2482 client pointer
 156  * @param cmd   DS2482_CMD_RESET,
 157  *              DS2482_CMD_1WIRE_RESET,
 158  *              DS2482_CMD_1WIRE_READ_BYTE
 159  * @return -1 on failure, 0 on success
 160  */
 161 static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
 162 {
 163         if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
 164                 return -1;
 165
 166         pdev->read_prt = DS2482_PTR_CODE_STATUS;
 167         return 0;
 168 }
 169
 170 /**
 171  * Sends a command with a parameter
 172  * @param pdev  The ds2482 client pointer
 173  * @param cmd   DS2482_CMD_WRITE_CONFIG,
 174  *              DS2482_CMD_1WIRE_SINGLE_BIT,
 175  *              DS2482_CMD_1WIRE_WRITE_BYTE,
 176  *              DS2482_CMD_1WIRE_TRIPLET
 177  * @param byte  The data to send
 178  * @return -1 on failure, 0 on success
 179  */
 180 static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
 181                                        u8 cmd, u8 byte)
 182 {
 183         if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
 184                 return -1;
 185
 186         /* all cmds leave in STATUS, except CONFIG */
 187         pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
 188                          DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
 189         return 0;
 190 }
 191
 192
 193 /*
 194  * 1-Wire interface code
 195  */
 196
 197 #define DS2482_WAIT_IDLE_TIMEOUT        100
 198
 199 /**
 200  * Waits until the 1-wire interface is idle (not busy)
 201  *
 202  * @param pdev Pointer to the device structure
 203  * @return the last value read from status or -1 (failure)
 204  */
 205 static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
 206 {
 207         int temp = -1;
 208         int retries = 0;
 209
 210         if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
 211                 do {
 212                         temp = i2c_smbus_read_byte(pdev->client);
 213                 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
 214                          (++retries < DS2482_WAIT_IDLE_TIMEOUT));
 215         }
 216
 217         if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
 218                 printk(KERN_ERR "%s: timeout on channel %d\n",
 219                        __func__, pdev->channel);
 220
 221         return temp;
 222 }
 223
 224 /**
 225  * Selects a w1 channel.
 226  * The 1-wire interface must be idle before calling this function.
 227  *
 228  * @param pdev          The ds2482 client pointer
 229  * @param channel       0-7
 230  * @return              -1 (failure) or 0 (success)
 231  */
 232 static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
 233 {
 234         if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
 235                                       ds2482_chan_wr[channel]) < 0)
 236                 return -1;
 237
 238         pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
 239         pdev->channel = -1;
 240         if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
 241                 pdev->channel = channel;
 242                 return 0;
 243         }
 244         return -1;
 245 }
 246
 247
 248 /**
 249  * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
 250  *
 251  * @param data  The ds2482 channel pointer
 252  * @param bit   The level to write: 0 or non-zero
 253  * @return      The level read: 0 or 1
 254  */
 255 static u8 ds2482_w1_touch_bit(void *data, u8 bit)
 256 {
 257         struct ds2482_w1_chan *pchan = data;
 258         struct ds2482_data    *pdev = pchan->pdev;
 259         int status = -1;
 260
 261         mutex_lock(&pdev->access_lock);
 262
 263         /* Select the channel */
 264         ds2482_wait_1wire_idle(pdev);
 265         if (pdev->w1_count > 1)
 266                 ds2482_set_channel(pdev, pchan->channel);
 267
 268         /* Send the touch command, wait until 1WB == 0, return the status */
 269         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
 270                                   bit ? 0xFF : 0))
 271                 status = ds2482_wait_1wire_idle(pdev);
 272
 273         mutex_unlock(&pdev->access_lock);
 274
 275         return (status & DS2482_REG_STS_SBR) ? 1 : 0;
 276 }
 277
 278 /**
 279  * Performs the triplet function, which reads two bits and writes a bit.
 280  * The bit written is determined by the two reads:
 281  *   00 => dbit, 01 => 0, 10 => 1
 282  *
 283  * @param data  The ds2482 channel pointer
 284  * @param dbit  The direction to choose if both branches are valid
 285  * @return      b0=read1 b1=read2 b3=bit written
 286  */
 287 static u8 ds2482_w1_triplet(void *data, u8 dbit)
 288 {
 289         struct ds2482_w1_chan *pchan = data;
 290         struct ds2482_data    *pdev = pchan->pdev;
 291         int status = (3 << 5);
 292
 293         mutex_lock(&pdev->access_lock);
 294
 295         /* Select the channel */
 296         ds2482_wait_1wire_idle(pdev);
 297         if (pdev->w1_count > 1)
 298                 ds2482_set_channel(pdev, pchan->channel);
 299
 300         /* Send the triplet command, wait until 1WB == 0, return the status */
 301         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
 302                                   dbit ? 0xFF : 0))
 303                 status = ds2482_wait_1wire_idle(pdev);
 304
 305         mutex_unlock(&pdev->access_lock);
 306
 307         /* Decode the status */
 308         return (status >> 5);
 309 }
 310
 311 /**
 312  * Performs the write byte function.
 313  *
 314  * @param data  The ds2482 channel pointer
 315  * @param byte  The value to write
 316  */
 317 static void ds2482_w1_write_byte(void *data, u8 byte)
 318 {
 319         struct ds2482_w1_chan *pchan = data;
 320         struct ds2482_data    *pdev = pchan->pdev;
 321
 322         mutex_lock(&pdev->access_lock);
 323
 324         /* Select the channel */
 325         ds2482_wait_1wire_idle(pdev);
 326         if (pdev->w1_count > 1)
 327                 ds2482_set_channel(pdev, pchan->channel);
 328
 329         /* Send the write byte command */
 330         ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
 331
 332         mutex_unlock(&pdev->access_lock);
 333 }
 334
 335 /**
 336  * Performs the read byte function.
 337  *
 338  * @param data  The ds2482 channel pointer
 339  * @return      The value read
 340  */
 341 static u8 ds2482_w1_read_byte(void *data)
 342 {
 343         struct ds2482_w1_chan *pchan = data;
 344         struct ds2482_data    *pdev = pchan->pdev;
 345         int result;
 346
 347         mutex_lock(&pdev->access_lock);
 348
 349         /* Select the channel */
 350         ds2482_wait_1wire_idle(pdev);
 351         if (pdev->w1_count > 1)
 352                 ds2482_set_channel(pdev, pchan->channel);
 353
 354         /* Send the read byte command */
 355         ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
 356
 357         /* Wait until 1WB == 0 */
 358         ds2482_wait_1wire_idle(pdev);
 359
 360         /* Select the data register */
 361         ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
 362
 363         /* Read the data byte */
 364         result = i2c_smbus_read_byte(pdev->client);
 365
 366         mutex_unlock(&pdev->access_lock);
 367
 368         return result;
 369 }
 370
 371
 372 /**
 373  * Sends a reset on the 1-wire interface
 374  *
 375  * @param data  The ds2482 channel pointer
 376  * @return      0=Device present, 1=No device present or error
 377  */
 378 static u8 ds2482_w1_reset_bus(void *data)
 379 {
 380         struct ds2482_w1_chan *pchan = data;
 381         struct ds2482_data    *pdev = pchan->pdev;
 382         int err;
 383         u8 retval = 1;
 384
 385         mutex_lock(&pdev->access_lock);
 386
 387         /* Select the channel */
 388         ds2482_wait_1wire_idle(pdev);
 389         if (pdev->w1_count > 1)
 390                 ds2482_set_channel(pdev, pchan->channel);
 391
 392         /* Send the reset command */
 393         err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
 394         if (err >= 0) {
 395                 /* Wait until the reset is complete */
 396                 err = ds2482_wait_1wire_idle(pdev);
 397                 retval = !(err & DS2482_REG_STS_PPD);
 398
 399                 /* If the chip did reset since detect, re-config it */
 400                 if (err & DS2482_REG_STS_RST)
 401                         ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 402                                              0xF0);
 403         }
 404
 405         mutex_unlock(&pdev->access_lock);
 406
 407         return retval;
 408 }
 409
 410
 411 static int ds2482_probe(struct i2c_client *client,
 412                         const struct i2c_device_id *id)
 413 {
 414         struct ds2482_data *data;
 415         int err = -ENODEV;
 416         int temp1;
 417         int idx;
 418
 419         if (!i2c_check_functionality(client->adapter,
 420                                      I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
 421                                      I2C_FUNC_SMBUS_BYTE))
 422                 return -ENODEV;
 423
 424         if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
 425                 err = -ENOMEM;
 426                 goto exit;
 427         }
 428
 429         data->client = client;
 430         i2c_set_clientdata(client, data);
 431
 432         /* Reset the device (sets the read_ptr to status) */
 433         if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
 434                 dev_warn(&client->dev, "DS2482 reset failed.\n");
 435                 goto exit_free;
 436         }
 437
 438         /* Sleep at least 525ns to allow the reset to complete */
 439         ndelay(525);
 440
 441         /* Read the status byte - only reset bit and line should be set */
 442         temp1 = i2c_smbus_read_byte(client);
 443         if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
 444                 dev_warn(&client->dev, "DS2482 reset status "
 445                          "0x%02X - not a DS2482\n", temp1);
 446                 goto exit_free;
 447         }
 448
 449         /* Detect the 8-port version */
 450         data->w1_count = 1;
 451         if (ds2482_set_channel(data, 7) == 0)
 452                 data->w1_count = 8;
 453
 454         /* Set all config items to 0 (off) */
 455         ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 0xF0);
 456
 457         mutex_init(&data->access_lock);
 458
 459         /* Register 1-wire interface(s) */
 460         for (idx = 0; idx < data->w1_count; idx++) {
 461                 data->w1_ch[idx].pdev = data;
 462                 data->w1_ch[idx].channel = idx;
 463
 464                 /* Populate all the w1 bus master stuff */
 465                 data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
 466                 data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
 467                 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
 468                 data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
 469                 data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
 470                 data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
 471
 472                 err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
 473                 if (err) {
 474                         data->w1_ch[idx].pdev = NULL;
 475                         goto exit_w1_remove;
 476                 }
 477         }
 478
 479         return 0;
 480
 481 exit_w1_remove:
 482         for (idx = 0; idx < data->w1_count; idx++) {
 483                 if (data->w1_ch[idx].pdev != NULL)
 484                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 485         }
 486 exit_free:
 487         kfree(data);
 488 exit:
 489         return err;
 490 }
 491
 492 static int ds2482_remove(struct i2c_client *client)
 493 {
 494         struct ds2482_data   *data = i2c_get_clientdata(client);
 495         int idx;
 496
 497         /* Unregister the 1-wire bridge(s) */
 498         for (idx = 0; idx < data->w1_count; idx++) {
 499                 if (data->w1_ch[idx].pdev != NULL)
 500                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 501         }
 502
 503         /* Free the memory */
 504         kfree(data);
 505         return 0;
 506 }
 507
 508 module_i2c_driver(ds2482_driver);
 509
 510 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
 511 MODULE_DESCRIPTION("DS2482 driver");
 512 MODULE_LICENSE("GPL");