drivers/w1/masters/ds2482.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
ds2482_calculate_config
ds2482_select_register
ds2482_send_cmd
ds2482_send_cmd_data
ds2482_wait_1wire_idle
ds2482_set_channel
ds2482_w1_touch_bit
ds2482_w1_triplet
ds2482_w1_write_byte
ds2482_w1_read_byte
ds2482_w1_reset_bus
ds2482_w1_set_pullup
ds2482_probe
ds2482_remove
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /**
   3  * ds2482.c - provides i2c to w1-master bridge(s)
   4  * Copyright (C) 2005  Ben Gardner <bgardner@wabtec.com>
   5  *
   6  * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).
   7  * It is a I2C to 1-wire bridge.
   8  * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
   9  * The complete datasheet can be obtained from MAXIM's website at:
  10  *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
  11  */
  12 
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/slab.h>
  16 #include <linux/i2c.h>
  17 #include <linux/delay.h>
  18 #include <asm/delay.h>
  19 
  20 #include <linux/w1.h>
  21 
  22 /**
  23  * Allow the active pullup to be disabled, default is enabled.
  24  *
  25  * Note from the DS2482 datasheet:
  26  * The APU bit controls whether an active pullup (controlled slew-rate
  27  * transistor) or a passive pullup (Rwpu resistor) will be used to drive
  28  * a 1-Wire line from low to high. When APU = 0, active pullup is disabled
  29  * (resistor mode). Active Pullup should always be selected unless there is
  30  * only a single slave on the 1-Wire line.
  31  */
  32 static int ds2482_active_pullup = 1;
  33 module_param_named(active_pullup, ds2482_active_pullup, int, 0644);
  34 MODULE_PARM_DESC(active_pullup, "Active pullup (apply to all buses): " \
  35                                 "0-disable, 1-enable (default)");
  36 
  37 /* extra configurations - e.g. 1WS */
  38 static int extra_config;
  39 module_param(extra_config, int, S_IRUGO | S_IWUSR);
  40 MODULE_PARM_DESC(extra_config, "Extra Configuration settings 1=APU,2=PPM,3=SPU,8=1WS");
  41 
  42 /**
  43  * The DS2482 registers - there are 3 registers that are addressed by a read
  44  * pointer. The read pointer is set by the last command executed.
  45  *
  46  * To read the data, issue a register read for any address
  47  */
  48 #define DS2482_CMD_RESET                0xF0    /* No param */
  49 #define DS2482_CMD_SET_READ_PTR         0xE1    /* Param: DS2482_PTR_CODE_xxx */
  50 #define DS2482_CMD_CHANNEL_SELECT       0xC3    /* Param: Channel byte - DS2482-800 only */
  51 #define DS2482_CMD_WRITE_CONFIG         0xD2    /* Param: Config byte */
  52 #define DS2482_CMD_1WIRE_RESET          0xB4    /* Param: None */
  53 #define DS2482_CMD_1WIRE_SINGLE_BIT     0x87    /* Param: Bit byte (bit7) */
  54 #define DS2482_CMD_1WIRE_WRITE_BYTE     0xA5    /* Param: Data byte */
  55 #define DS2482_CMD_1WIRE_READ_BYTE      0x96    /* Param: None */
  56 /* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
  57 #define DS2482_CMD_1WIRE_TRIPLET        0x78    /* Param: Dir byte (bit7) */
  58 
  59 /* Values for DS2482_CMD_SET_READ_PTR */
  60 #define DS2482_PTR_CODE_STATUS          0xF0
  61 #define DS2482_PTR_CODE_DATA            0xE1
  62 #define DS2482_PTR_CODE_CHANNEL         0xD2    /* DS2482-800 only */
  63 #define DS2482_PTR_CODE_CONFIG          0xC3
  64 
  65 /**
  66  * Configure Register bit definitions
  67  * The top 4 bits always read 0.
  68  * To write, the top nibble must be the 1's compl. of the low nibble.
  69  */
  70 #define DS2482_REG_CFG_1WS              0x08    /* 1-wire speed */
  71 #define DS2482_REG_CFG_SPU              0x04    /* strong pull-up */
  72 #define DS2482_REG_CFG_PPM              0x02    /* presence pulse masking */
  73 #define DS2482_REG_CFG_APU              0x01    /* active pull-up */
  74 
  75 
  76 /**
  77  * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
  78  * To set the channel, write the value at the index of the channel.
  79  * Read and compare against the corresponding value to verify the change.
  80  */
  81 static const u8 ds2482_chan_wr[8] =
  82         { 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
  83 static const u8 ds2482_chan_rd[8] =
  84         { 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
  85 
  86 
  87 /**
  88  * Status Register bit definitions (read only)
  89  */
  90 #define DS2482_REG_STS_DIR              0x80
  91 #define DS2482_REG_STS_TSB              0x40
  92 #define DS2482_REG_STS_SBR              0x20
  93 #define DS2482_REG_STS_RST              0x10
  94 #define DS2482_REG_STS_LL               0x08
  95 #define DS2482_REG_STS_SD               0x04
  96 #define DS2482_REG_STS_PPD              0x02
  97 #define DS2482_REG_STS_1WB              0x01
  98 
  99 /*
 100  * Client data (each client gets its own)
 101  */
 102 
 103 struct ds2482_data;
 104 
 105 struct ds2482_w1_chan {
 106         struct ds2482_data      *pdev;
 107         u8                      channel;
 108         struct w1_bus_master    w1_bm;
 109 };
 110 
 111 struct ds2482_data {
 112         struct i2c_client       *client;
 113         struct mutex            access_lock;
 114 
 115         /* 1-wire interface(s) */
 116         int                     w1_count;       /* 1 or 8 */
 117         struct ds2482_w1_chan   w1_ch[8];
 118 
 119         /* per-device values */
 120         u8                      channel;
 121         u8                      read_prt;       /* see DS2482_PTR_CODE_xxx */
 122         u8                      reg_config;
 123 };
 124 
 125 
 126 /**
 127  * Helper to calculate values for configuration register
 128  * @param conf the raw config value
 129  * @return the value w/ complements that can be written to register
 130  */
 131 static inline u8 ds2482_calculate_config(u8 conf)
 132 {
 133         conf |= extra_config;
 134 
 135         if (ds2482_active_pullup)
 136                 conf |= DS2482_REG_CFG_APU;
 137 
 138         return conf | ((~conf & 0x0f) << 4);
 139 }
 140 
 141 
 142 /**
 143  * Sets the read pointer.
 144  * @param pdev          The ds2482 client pointer
 145  * @param read_ptr      see DS2482_PTR_CODE_xxx above
 146  * @return -1 on failure, 0 on success
 147  */
 148 static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
 149 {
 150         if (pdev->read_prt != read_ptr) {
 151                 if (i2c_smbus_write_byte_data(pdev->client,
 152                                               DS2482_CMD_SET_READ_PTR,
 153                                               read_ptr) < 0)
 154                         return -1;
 155 
 156                 pdev->read_prt = read_ptr;
 157         }
 158         return 0;
 159 }
 160 
 161 /**
 162  * Sends a command without a parameter
 163  * @param pdev  The ds2482 client pointer
 164  * @param cmd   DS2482_CMD_RESET,
 165  *              DS2482_CMD_1WIRE_RESET,
 166  *              DS2482_CMD_1WIRE_READ_BYTE
 167  * @return -1 on failure, 0 on success
 168  */
 169 static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
 170 {
 171         if (i2c_smbus_write_byte(pdev->client, cmd) < 0)
 172                 return -1;
 173 
 174         pdev->read_prt = DS2482_PTR_CODE_STATUS;
 175         return 0;
 176 }
 177 
 178 /**
 179  * Sends a command with a parameter
 180  * @param pdev  The ds2482 client pointer
 181  * @param cmd   DS2482_CMD_WRITE_CONFIG,
 182  *              DS2482_CMD_1WIRE_SINGLE_BIT,
 183  *              DS2482_CMD_1WIRE_WRITE_BYTE,
 184  *              DS2482_CMD_1WIRE_TRIPLET
 185  * @param byte  The data to send
 186  * @return -1 on failure, 0 on success
 187  */
 188 static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
 189                                        u8 cmd, u8 byte)
 190 {
 191         if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)
 192                 return -1;
 193 
 194         /* all cmds leave in STATUS, except CONFIG */
 195         pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
 196                          DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
 197         return 0;
 198 }
 199 
 200 
 201 /*
 202  * 1-Wire interface code
 203  */
 204 
 205 #define DS2482_WAIT_IDLE_TIMEOUT        100
 206 
 207 /**
 208  * Waits until the 1-wire interface is idle (not busy)
 209  *
 210  * @param pdev Pointer to the device structure
 211  * @return the last value read from status or -1 (failure)
 212  */
 213 static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
 214 {
 215         int temp = -1;
 216         int retries = 0;
 217 
 218         if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
 219                 do {
 220                         temp = i2c_smbus_read_byte(pdev->client);
 221                 } while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
 222                          (++retries < DS2482_WAIT_IDLE_TIMEOUT));
 223         }
 224 
 225         if (retries >= DS2482_WAIT_IDLE_TIMEOUT)
 226                 pr_err("%s: timeout on channel %d\n",
 227                        __func__, pdev->channel);
 228 
 229         return temp;
 230 }
 231 
 232 /**
 233  * Selects a w1 channel.
 234  * The 1-wire interface must be idle before calling this function.
 235  *
 236  * @param pdev          The ds2482 client pointer
 237  * @param channel       0-7
 238  * @return              -1 (failure) or 0 (success)
 239  */
 240 static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
 241 {
 242         if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,
 243                                       ds2482_chan_wr[channel]) < 0)
 244                 return -1;
 245 
 246         pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
 247         pdev->channel = -1;
 248         if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {
 249                 pdev->channel = channel;
 250                 return 0;
 251         }
 252         return -1;
 253 }
 254 
 255 
 256 /**
 257  * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
 258  *
 259  * @param data  The ds2482 channel pointer
 260  * @param bit   The level to write: 0 or non-zero
 261  * @return      The level read: 0 or 1
 262  */
 263 static u8 ds2482_w1_touch_bit(void *data, u8 bit)
 264 {
 265         struct ds2482_w1_chan *pchan = data;
 266         struct ds2482_data    *pdev = pchan->pdev;
 267         int status = -1;
 268 
 269         mutex_lock(&pdev->access_lock);
 270 
 271         /* Select the channel */
 272         ds2482_wait_1wire_idle(pdev);
 273         if (pdev->w1_count > 1)
 274                 ds2482_set_channel(pdev, pchan->channel);
 275 
 276         /* Send the touch command, wait until 1WB == 0, return the status */
 277         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
 278                                   bit ? 0xFF : 0))
 279                 status = ds2482_wait_1wire_idle(pdev);
 280 
 281         mutex_unlock(&pdev->access_lock);
 282 
 283         return (status & DS2482_REG_STS_SBR) ? 1 : 0;
 284 }
 285 
 286 /**
 287  * Performs the triplet function, which reads two bits and writes a bit.
 288  * The bit written is determined by the two reads:
 289  *   00 => dbit, 01 => 0, 10 => 1
 290  *
 291  * @param data  The ds2482 channel pointer
 292  * @param dbit  The direction to choose if both branches are valid
 293  * @return      b0=read1 b1=read2 b3=bit written
 294  */
 295 static u8 ds2482_w1_triplet(void *data, u8 dbit)
 296 {
 297         struct ds2482_w1_chan *pchan = data;
 298         struct ds2482_data    *pdev = pchan->pdev;
 299         int status = (3 << 5);
 300 
 301         mutex_lock(&pdev->access_lock);
 302 
 303         /* Select the channel */
 304         ds2482_wait_1wire_idle(pdev);
 305         if (pdev->w1_count > 1)
 306                 ds2482_set_channel(pdev, pchan->channel);
 307 
 308         /* Send the triplet command, wait until 1WB == 0, return the status */
 309         if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
 310                                   dbit ? 0xFF : 0))
 311                 status = ds2482_wait_1wire_idle(pdev);
 312 
 313         mutex_unlock(&pdev->access_lock);
 314 
 315         /* Decode the status */
 316         return (status >> 5);
 317 }
 318 
 319 /**
 320  * Performs the write byte function.
 321  *
 322  * @param data  The ds2482 channel pointer
 323  * @param byte  The value to write
 324  */
 325 static void ds2482_w1_write_byte(void *data, u8 byte)
 326 {
 327         struct ds2482_w1_chan *pchan = data;
 328         struct ds2482_data    *pdev = pchan->pdev;
 329 
 330         mutex_lock(&pdev->access_lock);
 331 
 332         /* Select the channel */
 333         ds2482_wait_1wire_idle(pdev);
 334         if (pdev->w1_count > 1)
 335                 ds2482_set_channel(pdev, pchan->channel);
 336 
 337         /* Send the write byte command */
 338         ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
 339 
 340         mutex_unlock(&pdev->access_lock);
 341 }
 342 
 343 /**
 344  * Performs the read byte function.
 345  *
 346  * @param data  The ds2482 channel pointer
 347  * @return      The value read
 348  */
 349 static u8 ds2482_w1_read_byte(void *data)
 350 {
 351         struct ds2482_w1_chan *pchan = data;
 352         struct ds2482_data    *pdev = pchan->pdev;
 353         int result;
 354 
 355         mutex_lock(&pdev->access_lock);
 356 
 357         /* Select the channel */
 358         ds2482_wait_1wire_idle(pdev);
 359         if (pdev->w1_count > 1)
 360                 ds2482_set_channel(pdev, pchan->channel);
 361 
 362         /* Send the read byte command */
 363         ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
 364 
 365         /* Wait until 1WB == 0 */
 366         ds2482_wait_1wire_idle(pdev);
 367 
 368         /* Select the data register */
 369         ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
 370 
 371         /* Read the data byte */
 372         result = i2c_smbus_read_byte(pdev->client);
 373 
 374         mutex_unlock(&pdev->access_lock);
 375 
 376         return result;
 377 }
 378 
 379 
 380 /**
 381  * Sends a reset on the 1-wire interface
 382  *
 383  * @param data  The ds2482 channel pointer
 384  * @return      0=Device present, 1=No device present or error
 385  */
 386 static u8 ds2482_w1_reset_bus(void *data)
 387 {
 388         struct ds2482_w1_chan *pchan = data;
 389         struct ds2482_data    *pdev = pchan->pdev;
 390         int err;
 391         u8 retval = 1;
 392 
 393         mutex_lock(&pdev->access_lock);
 394 
 395         /* Select the channel */
 396         ds2482_wait_1wire_idle(pdev);
 397         if (pdev->w1_count > 1)
 398                 ds2482_set_channel(pdev, pchan->channel);
 399 
 400         /* Send the reset command */
 401         err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
 402         if (err >= 0) {
 403                 /* Wait until the reset is complete */
 404                 err = ds2482_wait_1wire_idle(pdev);
 405                 retval = !(err & DS2482_REG_STS_PPD);
 406 
 407                 /* If the chip did reset since detect, re-config it */
 408                 if (err & DS2482_REG_STS_RST)
 409                         ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 410                                              ds2482_calculate_config(0x00));
 411         }
 412 
 413         mutex_unlock(&pdev->access_lock);
 414 
 415         return retval;
 416 }
 417 
 418 static u8 ds2482_w1_set_pullup(void *data, int delay)
 419 {
 420         struct ds2482_w1_chan *pchan = data;
 421         struct ds2482_data    *pdev = pchan->pdev;
 422         u8 retval = 1;
 423 
 424         /* if delay is non-zero activate the pullup,
 425          * the strong pullup will be automatically deactivated
 426          * by the master, so do not explicitly deactive it
 427          */
 428         if (delay) {
 429                 /* both waits are crucial, otherwise devices might not be
 430                  * powered long enough, causing e.g. a w1_therm sensor to
 431                  * provide wrong conversion results
 432                  */
 433                 ds2482_wait_1wire_idle(pdev);
 434                 /* note: it seems like both SPU and APU have to be set! */
 435                 retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
 436                         ds2482_calculate_config(DS2482_REG_CFG_SPU |
 437                                                 DS2482_REG_CFG_APU));
 438                 ds2482_wait_1wire_idle(pdev);
 439         }
 440 
 441         return retval;
 442 }
 443 
 444 
 445 static int ds2482_probe(struct i2c_client *client,
 446                         const struct i2c_device_id *id)
 447 {
 448         struct ds2482_data *data;
 449         int err = -ENODEV;
 450         int temp1;
 451         int idx;
 452 
 453         if (!i2c_check_functionality(client->adapter,
 454                                      I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
 455                                      I2C_FUNC_SMBUS_BYTE))
 456                 return -ENODEV;
 457 
 458         if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
 459                 err = -ENOMEM;
 460                 goto exit;
 461         }
 462 
 463         data->client = client;
 464         i2c_set_clientdata(client, data);
 465 
 466         /* Reset the device (sets the read_ptr to status) */
 467         if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
 468                 dev_warn(&client->dev, "DS2482 reset failed.\n");
 469                 goto exit_free;
 470         }
 471 
 472         /* Sleep at least 525ns to allow the reset to complete */
 473         ndelay(525);
 474 
 475         /* Read the status byte - only reset bit and line should be set */
 476         temp1 = i2c_smbus_read_byte(client);
 477         if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
 478                 dev_warn(&client->dev, "DS2482 reset status "
 479                          "0x%02X - not a DS2482\n", temp1);
 480                 goto exit_free;
 481         }
 482 
 483         /* Detect the 8-port version */
 484         data->w1_count = 1;
 485         if (ds2482_set_channel(data, 7) == 0)
 486                 data->w1_count = 8;
 487 
 488         /* Set all config items to 0 (off) */
 489         ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG,
 490                 ds2482_calculate_config(0x00));
 491 
 492         mutex_init(&data->access_lock);
 493 
 494         /* Register 1-wire interface(s) */
 495         for (idx = 0; idx < data->w1_count; idx++) {
 496                 data->w1_ch[idx].pdev = data;
 497                 data->w1_ch[idx].channel = idx;
 498 
 499                 /* Populate all the w1 bus master stuff */
 500                 data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
 501                 data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
 502                 data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
 503                 data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
 504                 data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
 505                 data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
 506                 data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
 507 
 508                 err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
 509                 if (err) {
 510                         data->w1_ch[idx].pdev = NULL;
 511                         goto exit_w1_remove;
 512                 }
 513         }
 514 
 515         return 0;
 516 
 517 exit_w1_remove:
 518         for (idx = 0; idx < data->w1_count; idx++) {
 519                 if (data->w1_ch[idx].pdev != NULL)
 520                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 521         }
 522 exit_free:
 523         kfree(data);
 524 exit:
 525         return err;
 526 }
 527 
 528 static int ds2482_remove(struct i2c_client *client)
 529 {
 530         struct ds2482_data   *data = i2c_get_clientdata(client);
 531         int idx;
 532 
 533         /* Unregister the 1-wire bridge(s) */
 534         for (idx = 0; idx < data->w1_count; idx++) {
 535                 if (data->w1_ch[idx].pdev != NULL)
 536                         w1_remove_master_device(&data->w1_ch[idx].w1_bm);
 537         }
 538 
 539         /* Free the memory */
 540         kfree(data);
 541         return 0;
 542 }
 543 
 544 /**
 545  * Driver data (common to all clients)
 546  */
 547 static const struct i2c_device_id ds2482_id[] = {
 548         { "ds2482", 0 },
 549         { }
 550 };
 551 MODULE_DEVICE_TABLE(i2c, ds2482_id);
 552 
 553 static struct i2c_driver ds2482_driver = {
 554         .driver = {
 555                 .name   = "ds2482",
 556         },
 557         .probe          = ds2482_probe,
 558         .remove         = ds2482_remove,
 559         .id_table       = ds2482_id,
 560 };
 561 module_i2c_driver(ds2482_driver);
 562 
 563 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
 564 MODULE_DESCRIPTION("DS2482 driver");
 565 
 566 MODULE_LICENSE("GPL");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/w1/masters/ds2482.c

DEFINITIONS
