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 <linux/gpio.h>
  22 #include <linux/platform_data/ds2482.h>
  23 #include <asm/delay.h>
  24
  25 #include "../w1.h"
  26 #include "../w1_int.h"
  27
  28 /**
  29  * The DS2482 registers - there are 3 registers that are addressed by a read
  30  * pointer. The read pointer is set by the last command executed.
  31  *
  32  * To read the data, issue a register read for any address
  33  */
  34 #define DS2482_CMD_RESET                0xF0    /* No param */
  35 #define DS2482_CMD_SET_READ_PTR         0xE1    /* Param: DS2482_PTR_CODE_xxx */
  36 #define DS2482_CMD_CHANNEL_SELECT       0xC3    /* Param: Channel byte - DS2482-800 only */
  37 #define DS2482_CMD_WRITE_CONFIG         0xD2    /* Param: Config byte */
  38 #define DS2482_CMD_1WIRE_RESET          0xB4    /* Param: None */
  39 #define DS2482_CMD_1WIRE_SINGLE_BIT     0x87    /* Param: Bit byte (bit7) */
  40 #define DS2482_CMD_1WIRE_WRITE_BYTE     0xA5    /* Param: Data byte */
  41 #define DS2482_CMD_1WIRE_READ_BYTE      0x96    /* Param: None */
  42 /* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
  43 #define DS2482_CMD_1WIRE_TRIPLET        0x78    /* Param: Dir byte (bit7) */
  44
  45 /* Values for DS2482_CMD_SET_READ_PTR */
  46 #define DS2482_PTR_CODE_STATUS          0xF0
  47 #define DS2482_PTR_CODE_DATA            0xE1
  48 #define DS2482_PTR_CODE_CHANNEL         0xD2    /* DS2482-800 only */
  49 #define DS2482_PTR_CODE_CONFIG          0xC3
  50
  51 /**
  52  * Configure Register bit definitions
  53  * The top 4 bits always read 0.
  54  * To write, the top nibble must be the 1's compl. of the low nibble.
  55  */
  56 #define DS2482_REG_CFG_1WS              0x08    /* 1-wire speed */
  57 #define DS2482_REG_CFG_SPU              0x04    /* strong pull-up */
  58 #define DS2482_REG_CFG_PPM              0x02    /* presence pulse masking */
  59 #define DS2482_REG_CFG_APU              0x01    /* active pull-up */
  60
  61
  62 /**
  63  * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
  64  * To set the channel, write the value at the index of the channel.
  65  * Read and compare against the corresponding value to verify the change.
  66  */
  67 static const u8 ds2482_chan_wr[8] =
  68         { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
  69 static const u8 ds2482_chan_rd[8] =
  70         { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
  71
  72
  73 /**
  74  * Status Register bit definitions (read only)
  75  */
  76 #define DS2482_REG_STS_DIR              0x80
  77 #define DS2482_REG_STS_TSB              0x40
  78 #define DS2482_REG_STS_SBR              0x20
  79 #define DS2482_REG_STS_RST              0x10
  80 #define DS2482_REG_STS_LL               0x08
  81 #define DS2482_REG_STS_SD               0x04
  82 #define DS2482_REG_STS_PPD              0x02
  83 #define DS2482_REG_STS_1WB              0x01
  84
  85
  86 static int ds2482_probe(struct i2c_client *client,
  87                         const struct i2c_device_id *id);
  88 static int ds2482_remove(struct i2c_client *client);
  89 static int ds2482_suspend(struct device *dev);
  90 static int ds2482_resume(struct device *dev);
  91
  92 /**
  93  * Driver data (common to all clients)
  94  */
  95 static const struct i2c_device_id ds2482_id[] = {
  96         { "ds2482", 0 },
  97         { }
  98 };
  99
 100 static const struct dev_pm_ops ds2482_pm_ops = {
 101         .suspend = ds2482_suspend,
 102         .resume = ds2482_resume,
 103 };
 104
 105 static struct i2c_driver ds2482_driver = {
 106         .driver = {
 107                 .owner  = THIS_MODULE,
 108                 .name   = "ds2482",
 109                 .pm = &ds2482_pm_ops,
 110         },
 111         .probe          = ds2482_probe,
 112         .remove         = ds2482_remove,
 113         .id_table       = ds2482_id,
 114 };
 115
 116 /*
 117  * Client data (each client gets its own)
 118  */
 119
 120 struct ds2482_data;
 121
 122 struct ds2482_w1_chan {
 123         struct ds2482_data      *pdev;
 124         u8                      channel;
 125         struct w1_bus_master    w1_bm;
 126 };
 127
 128 struct ds2482_data {
 129         struct i2c_client       *client;
 130         struct mutex            access_lock;
 131         int                     slpz_gpio;
 132
 133         /* 1-wire interface(s) */
 134         int                     w1_count;       /* 1 or 8 */
 135         struct ds2482_w1_chan   w1_ch[8];
 136
 137         /* per-device values */
 138         u8                      channel;
 139         u8                      read_prt;       /* see DS2482_PTR_CODE_xxx */
 140         u8                      reg_config;
 141 };
 142
 143
 144 /**
 145  * Helper to calculate values for configuration register
 146  * @param conf the raw config value
 147  * @return the value w/ complements that can be written to register
 148  */
 149 static inline u8 ds2482_calculate_config(u8 conf)
 150 {
 151         return conf | ((~conf & 0x0f) << 4);
 152 }
 153
 154
 155 /**
 156  * Sets the read pointer.
 157  * @param pdev          The ds2482 client pointer
 158  * @param read_ptr      see DS2482_PTR_CODE_xxx above
 159  * @return -1 on failure, 0 on success
 160  */
 161 static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
 162 {
 163         if (pdev->read_prt != read_ptr) {
 164                 if (i2c_smbus_write_byte_data(pdev->client,
 165                                               DS2482_CMD_SET_READ_PTR,
 166                                               read_ptr) < 0)
 167                         return -1;
 168
 169                 pdev->read_prt = read_ptr;
 170         }
 171         return 0;
 172 }
 173
 174 /**
 175  * Sends a command without a parameter
 176  * @param pdev  The ds2482 client pointer
 177  * @param cmd   DS2482_CMD_RESET,
 178  *              DS2482_CMD_1WIRE_RESET,
 179  *              DS2482_CMD_1WIRE_READ_BYTE
 180  * @return -1 on failure, 0 on success
 181  */
 182 static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
 183 {
 184         if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
 185                 return -1;
 186
 187         pdev->read_prt = DS2482_PTR_CODE_STATUS;
 188         return 0;
 189 }
 190
 191 /**
 192  * Sends a command with a parameter
 193  * @param pdev  The ds2482 client pointer
 194  * @param cmd   DS2482_CMD_WRITE_CONFIG,
 195  *              DS2482_CMD_1WIRE_SINGLE_BIT,
 196  *              DS2482_CMD_1WIRE_WRITE_BYTE,
 197  *              DS2482_CMD_1WIRE_TRIPLET
 198  * @param byte  The data to send
 199  * @return -1 on failure, 0 on success
 200  */
 201 static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
 202                                        u8 cmd, u8 byte)
 203 {
 204         if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
 205                 return -1;
 206
 207         /* all cmds leave in STATUS, except CONFIG */
 208         pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
 209                          DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
 210         return 0;
 211 }
 212
 213
 214 /*
 215  * 1-Wire interface code
 216  */
 217
 218 #define DS2482_WAIT_IDLE_TIMEOUT        100
 219
 220 /**
 221  * Waits until the 1-wire interface is idle (not busy)
 222  *
 223  * @param pdev Pointer to the device structure
 224  * @return the last value read from status or -1 (failure)
 225  */
 226 static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
 227 {
 228         int temp = -1;
 229         int retries = 0;
 230
 231         if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
 232                 do {
 233                         temp = i2c_smbus_read_byte(pdev->client);
 234                 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
 235                          (++retries < DS2482_WAIT_IDLE_TIMEOUT));
 236         }
 237
 238         if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
 239                 printk(KERN_ERR "%s: timeout on channel %d\n",
 240                        __func__, pdev->channel);
 241
 242         return temp;
 243 }
 244
 245 /**
 246  * Selects a w1 channel.
 247  * The 1-wire interface must be idle before calling this function.
 248  *
 249  * @param pdev          The ds2482 client pointer
 250  * @param channel       0-7
 251  * @return              -1 (failure) or 0 (success)
 252  */
 253 static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
 254 {
 255         if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
 256                                       ds2482_chan_wr[channel]) < 0)
 257                 return -1;
 258
 259         pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
 260         pdev->channel = -1;
 261         if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
 262                 pdev->channel = channel;
 263                 return 0;
 264         }
 265         return -1;
 266 }
 267
 268
 269 /**
 270  * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
 271  *
 272  * @param data  The ds2482 channel pointer
 273  * @param bit   The level to write: 0 or non-zero
 274  * @return      The level read: 0 or 1
 275  */
 276 static u8 ds2482_w1_touch_bit(void *data, u8 bit)
 277 {
 278         struct ds2482_w1_chan *pchan = data;
 279         struct ds2482_data    *pdev = pchan->pdev;
 280         int status = -1;
 281
 282         mutex_lock(&pdev->access_lock);
 283
 284         /* Select the channel */
 285         ds2482_wait_1wire_idle(pdev);
 286         if (pdev->w1_count > 1)
 287                 ds2482_set_channel(pdev, pchan->channel);
 288
 289         /* Send the touch command, wait until 1WB == 0, return the status */
 290         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
 291                                   bit ? 0xFF : 0))
 292                 status = ds2482_wait_1wire_idle(pdev);
 293
 294         mutex_unlock(&pdev->access_lock);
 295
 296         return (status & DS2482_REG_STS_SBR) ? 1 : 0;
 297 }
 298
 299 /**
 300  * Performs the triplet function, which reads two bits and writes a bit.
 301  * The bit written is determined by the two reads:
 302  *   00 => dbit, 01 => 0, 10 => 1
 303  *
 304  * @param data  The ds2482 channel pointer
 305  * @param dbit  The direction to choose if both branches are valid
 306  * @return      b0=read1 b1=read2 b3=bit written
 307  */
 308 static u8 ds2482_w1_triplet(void *data, u8 dbit)
 309 {
 310         struct ds2482_w1_chan *pchan = data;
 311         struct ds2482_data    *pdev = pchan->pdev;
 312         int status = (3 << 5);
 313
 314         mutex_lock(&pdev->access_lock);
 315
 316         /* Select the channel */
 317         ds2482_wait_1wire_idle(pdev);
 318         if (pdev->w1_count > 1)
 319                 ds2482_set_channel(pdev, pchan->channel);
 320
 321         /* Send the triplet command, wait until 1WB == 0, return the status */
 322         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
 323                                   dbit ? 0xFF : 0))
 324                 status = ds2482_wait_1wire_idle(pdev);
 325
 326         mutex_unlock(&pdev->access_lock);
 327
 328         /* Decode the status */
 329         return (status >> 5);
 330 }
 331
 332 /**
 333  * Performs the write byte function.
 334  *
 335  * @param data  The ds2482 channel pointer
 336  * @param byte  The value to write
 337  */
 338 static void ds2482_w1_write_byte(void *data, u8 byte)
 339 {
 340         struct ds2482_w1_chan *pchan = data;
 341         struct ds2482_data    *pdev = pchan->pdev;
 342
 343         mutex_lock(&pdev->access_lock);
 344
 345         /* Select the channel */
 346         ds2482_wait_1wire_idle(pdev);
 347         if (pdev->w1_count > 1)
 348                 ds2482_set_channel(pdev, pchan->channel);
 349
 350         /* Send the write byte command */
 351         ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
 352
 353         mutex_unlock(&pdev->access_lock);
 354 }
 355
 356 /**
 357  * Performs the read byte function.
 358  *
 359  * @param data  The ds2482 channel pointer
 360  * @return      The value read
 361  */
 362 static u8 ds2482_w1_read_byte(void *data)
 363 {
 364         struct ds2482_w1_chan *pchan = data;
 365         struct ds2482_data    *pdev = pchan->pdev;
 366         int result;
 367
 368         mutex_lock(&pdev->access_lock);
 369
 370         /* Select the channel */
 371         ds2482_wait_1wire_idle(pdev);
 372         if (pdev->w1_count > 1)
 373                 ds2482_set_channel(pdev, pchan->channel);
 374
 375         /* Send the read byte command */
 376         ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
 377
 378         /* Wait until 1WB == 0 */
 379         ds2482_wait_1wire_idle(pdev);
 380
 381         /* Select the data register */
 382         ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
 383
 384         /* Read the data byte */
 385         result = i2c_smbus_read_byte(pdev->client);
 386
 387         mutex_unlock(&pdev->access_lock);
 388
 389         return result;
 390 }
 391
 392
 393 /**
 394  * Sends a reset on the 1-wire interface
 395  *
 396  * @param data  The ds2482 channel pointer
 397  * @return      0=Device present, 1=No device present or error
 398  */
 399 static u8 ds2482_w1_reset_bus(void *data)
 400 {
 401         struct ds2482_w1_chan *pchan = data;
 402         struct ds2482_data    *pdev = pchan->pdev;
 403         int err;
 404         u8 retval = 1;
 405
 406         mutex_lock(&pdev->access_lock);
 407
 408         /* Select the channel */
 409         ds2482_wait_1wire_idle(pdev);
 410         if (pdev->w1_count > 1)
 411                 ds2482_set_channel(pdev, pchan->channel);
 412
 413         /* Send the reset command */
 414         err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
 415         if (err >= 0) {
 416                 /* Wait until the reset is complete */
 417                 err = ds2482_wait_1wire_idle(pdev);
 418                 retval = !(err & DS2482_REG_STS_PPD);
 419
 420                 /* If the chip did reset since detect, re-config it */
 421                 if (err & DS2482_REG_STS_RST)
 422                         ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 423                                              ds2482_calculate_config(0x00));
 424         }
 425
 426         mutex_unlock(&pdev->access_lock);
 427
 428         return retval;
 429 }
 430
 431 static u8 ds2482_w1_set_pullup(void *data, int delay)
 432 {
 433         struct ds2482_w1_chan *pchan = data;
 434         struct ds2482_data    *pdev = pchan->pdev;
 435         u8 retval = 1;
 436
 437         /* if delay is non-zero activate the pullup,
 438          * the strong pullup will be automatically deactivated
 439          * by the master, so do not explicitly deactive it
 440          */
 441         if (delay) {
 442                 /* both waits are crucial, otherwise devices might not be
 443                  * powered long enough, causing e.g. a w1_therm sensor to
 444                  * provide wrong conversion results
 445                  */
 446                 ds2482_wait_1wire_idle(pdev);
 447                 /* note: it seems like both SPU and APU have to be set! */
 448                 retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 449                         ds2482_calculate_config(DS2482_REG_CFG_SPU |
 450                                                 DS2482_REG_CFG_APU));
 451                 ds2482_wait_1wire_idle(pdev);
 452         }
 453
 454         return retval;
 455 }
 456
 457 static int ds2482_suspend(struct device *dev)
 458 {
 459         struct i2c_client *client = to_i2c_client(dev);
 460         struct ds2482_data *data = i2c_get_clientdata(client);
 461
 462         if (data->slpz_gpio >= 0)
 463                 gpio_set_value(data->slpz_gpio, 0);
 464         return 0;
 465 }
 466
 467 static int ds2482_resume(struct device *dev)
 468 {
 469         struct i2c_client *client = to_i2c_client(dev);
 470         struct ds2482_data *data = i2c_get_clientdata(client);
 471
 472         if (data->slpz_gpio >= 0)
 473                 gpio_set_value(data->slpz_gpio, 1);
 474         return 0;
 475 }
 476
 477 static int ds2482_probe(struct i2c_client *client,
 478                         const struct i2c_device_id *id)
 479 {
 480         struct ds2482_data *data;
 481         struct ds2482_platform_data *pdata;
 482         int err = -ENODEV;
 483         int temp1;
 484         int idx;
 485
 486         if (!i2c_check_functionality(client->adapter,
 487                                      I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
 488                                      I2C_FUNC_SMBUS_BYTE))
 489                 return -ENODEV;
 490
 491         if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
 492                 err = -ENOMEM;
 493                 goto exit;
 494         }
 495
 496         data->client = client;
 497         i2c_set_clientdata(client, data);
 498
 499         /* Reset the device (sets the read_ptr to status) */
 500         if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
 501                 dev_warn(&client->dev, "DS2482 reset failed.\n");
 502                 goto exit_free;
 503         }
 504
 505         /* Sleep at least 525ns to allow the reset to complete */
 506         ndelay(525);
 507
 508         /* Read the status byte - only reset bit and line should be set */
 509         temp1 = i2c_smbus_read_byte(client);
 510         if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
 511                 dev_warn(&client->dev, "DS2482 reset status "
 512                          "0x%02X - not a DS2482\n", temp1);
 513                 goto exit_free;
 514         }
 515
 516         /* Detect the 8-port version */
 517         data->w1_count = 1;
 518         if (ds2482_set_channel(data, 7) == 0)
 519                 data->w1_count = 8;
 520
 521         /* Set all config items to 0 (off) */
 522         ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
 523                 ds2482_calculate_config(0x00));
 524
 525         mutex_init(&data->access_lock);
 526
 527         /* Register 1-wire interface(s) */
 528         for (idx = 0; idx < data->w1_count; idx++) {
 529                 data->w1_ch[idx].pdev = data;
 530                 data->w1_ch[idx].channel = idx;
 531
 532                 /* Populate all the w1 bus master stuff */
 533                 data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
 534                 data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
 535                 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
 536                 data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
 537                 data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
 538                 data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
 539                 data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
 540
 541                 err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
 542                 if (err) {
 543                         data->w1_ch[idx].pdev = NULL;
 544                         goto exit_w1_remove;
 545                 }
 546         }
 547
 548         pdata = client->dev.platform_data;
 549         data->slpz_gpio = pdata ? pdata->slpz_gpio : -1;
 550
 551         if (data->slpz_gpio >= 0) {
 552                 err = gpio_request_one(data->slpz_gpio, GPIOF_OUT_INIT_HIGH,
 553                                        "ds2482.slpz");
 554                 if (err < 0)
 555                         goto exit_w1_remove;
 556         }
 557
 558         return 0;
 559
 560 exit_w1_remove:
 561         for (idx = 0; idx < data->w1_count; idx++) {
 562                 if (data->w1_ch[idx].pdev != NULL)
 563                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 564         }
 565 exit_free:
 566         kfree(data);
 567 exit:
 568         return err;
 569 }
 570
 571 static int ds2482_remove(struct i2c_client *client)
 572 {
 573         struct ds2482_data   *data = i2c_get_clientdata(client);
 574         int idx;
 575
 576         /* Unregister the 1-wire bridge(s) */
 577         for (idx = 0; idx < data->w1_count; idx++) {
 578                 if (data->w1_ch[idx].pdev != NULL)
 579                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 580         }
 581
 582         if (data->slpz_gpio >= 0) {
 583                 gpio_set_value(data->slpz_gpio, 0);
 584                 gpio_free(data->slpz_gpio);
 585         }
 586
 587         /* Free the memory */
 588         kfree(data);
 589         return 0;
 590 }
 591
 592 module_i2c_driver(ds2482_driver);
 593
 594 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
 595 MODULE_DESCRIPTION("DS2482 driver");
 596 MODULE_LICENSE("GPL");