drivers/iio/adc/max9611.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
max9611_read_single
max9611_read_csa_voltage
max9611_read_raw
max9611_shunt_resistor_show
max9611_init
max9611_probe
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * iio/adc/max9611.c
   4  *
   5  * Maxim max9611/max9612 high side current sense amplifier with
   6  * 12-bit ADC interface.
   7  *
   8  * Copyright (C) 2017 Jacopo Mondi
   9  */
  10 
  11 /*
  12  * This driver supports input common-mode voltage, current-sense
  13  * amplifier with programmable gains and die temperature reading from
  14  * Maxim max9611/max9612.
  15  *
  16  * Op-amp, analog comparator, and watchdog functionalities are not
  17  * supported by this driver.
  18  */
  19 
  20 #include <linux/delay.h>
  21 #include <linux/i2c.h>
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24 #include <linux/module.h>
  25 #include <linux/of_device.h>
  26 
  27 #define DRIVER_NAME                     "max9611"
  28 
  29 /* max9611 register addresses */
  30 #define MAX9611_REG_CSA_DATA            0x00
  31 #define MAX9611_REG_RS_DATA             0x02
  32 #define MAX9611_REG_TEMP_DATA           0x08
  33 #define MAX9611_REG_CTRL1               0x0a
  34 #define MAX9611_REG_CTRL2               0x0b
  35 
  36 /* max9611 REG1 mux configuration options */
  37 #define MAX9611_MUX_MASK                GENMASK(3, 0)
  38 #define MAX9611_MUX_SENSE_1x            0x00
  39 #define MAX9611_MUX_SENSE_4x            0x01
  40 #define MAX9611_MUX_SENSE_8x            0x02
  41 #define MAX9611_INPUT_VOLT              0x03
  42 #define MAX9611_MUX_TEMP                0x06
  43 
  44 /* max9611 voltage (both csa and input) helper macros */
  45 #define MAX9611_VOLTAGE_SHIFT           0x04
  46 #define MAX9611_VOLTAGE_RAW(_r)         ((_r) >> MAX9611_VOLTAGE_SHIFT)
  47 
  48 /*
  49  * max9611 current sense amplifier voltage output:
  50  * LSB and offset values depends on selected gain (1x, 4x, 8x)
  51  *
  52  * GAIN         LSB (nV)        OFFSET (LSB steps)
  53  * 1x           107500          1
  54  * 4x           26880           1
  55  * 8x           13440           3
  56  *
  57  * The complete formula to calculate current sense voltage is:
  58  *     (((adc_read >> 4) - offset) / ((1 / LSB) * 10^-3)
  59  */
  60 #define MAX9611_CSA_1X_LSB_nV           107500
  61 #define MAX9611_CSA_4X_LSB_nV           26880
  62 #define MAX9611_CSA_8X_LSB_nV           13440
  63 
  64 #define MAX9611_CSA_1X_OFFS_RAW         1
  65 #define MAX9611_CSA_4X_OFFS_RAW         1
  66 #define MAX9611_CSA_8X_OFFS_RAW         3
  67 
  68 /*
  69  * max9611 common input mode (CIM): LSB is 14mV, with 14mV offset at 25 C
  70  *
  71  * The complete formula to calculate input common voltage is:
  72  *     (((adc_read >> 4) * 1000) - offset) / (1 / 14 * 1000)
  73  */
  74 #define MAX9611_CIM_LSB_mV              14
  75 #define MAX9611_CIM_OFFSET_RAW          1
  76 
  77 /*
  78  * max9611 temperature reading: LSB is 480 milli degrees Celsius
  79  *
  80  * The complete formula to calculate temperature is:
  81  *     ((adc_read >> 7) * 1000) / (1 / 480 * 1000)
  82  */
  83 #define MAX9611_TEMP_MAX_POS            0x7f80
  84 #define MAX9611_TEMP_MAX_NEG            0xff80
  85 #define MAX9611_TEMP_MIN_NEG            0xd980
  86 #define MAX9611_TEMP_MASK               GENMASK(15, 7)
  87 #define MAX9611_TEMP_SHIFT              0x07
  88 #define MAX9611_TEMP_RAW(_r)            ((_r) >> MAX9611_TEMP_SHIFT)
  89 #define MAX9611_TEMP_SCALE_NUM          1000000
  90 #define MAX9611_TEMP_SCALE_DIV          2083
  91 
  92 /*
  93  * Conversion time is 2 ms (typically) at Ta=25 degreeC
  94  * No maximum value is known, so play it safe.
  95  */
  96 #define MAX9611_CONV_TIME_US_RANGE      3000, 3300
  97 
  98 struct max9611_dev {
  99         struct device *dev;
 100         struct i2c_client *i2c_client;
 101         struct mutex lock;
 102         unsigned int shunt_resistor_uohm;
 103 };
 104 
 105 enum max9611_conf_ids {
 106         CONF_SENSE_1x,
 107         CONF_SENSE_4x,
 108         CONF_SENSE_8x,
 109         CONF_IN_VOLT,
 110         CONF_TEMP,
 111 };
 112 
 113 /**
 114  * max9611_mux_conf - associate ADC mux configuration with register address
 115  *                    where data shall be read from
 116  */
 117 static const unsigned int max9611_mux_conf[][2] = {
 118         /* CONF_SENSE_1x */
 119         { MAX9611_MUX_SENSE_1x, MAX9611_REG_CSA_DATA },
 120         /* CONF_SENSE_4x */
 121         { MAX9611_MUX_SENSE_4x, MAX9611_REG_CSA_DATA },
 122         /* CONF_SENSE_8x */
 123         { MAX9611_MUX_SENSE_8x, MAX9611_REG_CSA_DATA },
 124         /* CONF_IN_VOLT */
 125         { MAX9611_INPUT_VOLT, MAX9611_REG_RS_DATA },
 126         /* CONF_TEMP */
 127         { MAX9611_MUX_TEMP, MAX9611_REG_TEMP_DATA },
 128 };
 129 
 130 enum max9611_csa_gain {
 131         CSA_GAIN_1x,
 132         CSA_GAIN_4x,
 133         CSA_GAIN_8x,
 134 };
 135 
 136 enum max9611_csa_gain_params {
 137         CSA_GAIN_LSB_nV,
 138         CSA_GAIN_OFFS_RAW,
 139 };
 140 
 141 /**
 142  * max9611_csa_gain_conf - associate gain multiplier with LSB and
 143  *                         offset values.
 144  *
 145  * Group together parameters associated with configurable gain
 146  * on current sense amplifier path to ADC interface.
 147  * Current sense read routine adjusts gain until it gets a meaningful
 148  * value; use this structure to retrieve the correct LSB and offset values.
 149  */
 150 static const unsigned int max9611_gain_conf[][2] = {
 151         { /* [0] CSA_GAIN_1x */
 152                 MAX9611_CSA_1X_LSB_nV,
 153                 MAX9611_CSA_1X_OFFS_RAW,
 154         },
 155         { /* [1] CSA_GAIN_4x */
 156                 MAX9611_CSA_4X_LSB_nV,
 157                 MAX9611_CSA_4X_OFFS_RAW,
 158         },
 159         { /* [2] CSA_GAIN_8x */
 160                 MAX9611_CSA_8X_LSB_nV,
 161                 MAX9611_CSA_8X_OFFS_RAW,
 162         },
 163 };
 164 
 165 enum max9611_chan_addrs {
 166         MAX9611_CHAN_VOLTAGE_INPUT,
 167         MAX9611_CHAN_VOLTAGE_SENSE,
 168         MAX9611_CHAN_TEMPERATURE,
 169         MAX9611_CHAN_CURRENT_LOAD,
 170         MAX9611_CHAN_POWER_LOAD,
 171 };
 172 
 173 static const struct iio_chan_spec max9611_channels[] = {
 174         {
 175           .type                 = IIO_TEMP,
 176           .info_mask_separate   = BIT(IIO_CHAN_INFO_RAW) |
 177                                   BIT(IIO_CHAN_INFO_SCALE),
 178           .address              = MAX9611_CHAN_TEMPERATURE,
 179         },
 180         {
 181           .type                 = IIO_VOLTAGE,
 182           .info_mask_separate   = BIT(IIO_CHAN_INFO_PROCESSED),
 183           .address              = MAX9611_CHAN_VOLTAGE_SENSE,
 184           .indexed              = 1,
 185           .channel              = 0,
 186         },
 187         {
 188           .type                 = IIO_VOLTAGE,
 189           .info_mask_separate   = BIT(IIO_CHAN_INFO_RAW)   |
 190                                   BIT(IIO_CHAN_INFO_SCALE) |
 191                                   BIT(IIO_CHAN_INFO_OFFSET),
 192           .address              = MAX9611_CHAN_VOLTAGE_INPUT,
 193           .indexed              = 1,
 194           .channel              = 1,
 195         },
 196         {
 197           .type                 = IIO_CURRENT,
 198           .info_mask_separate   = BIT(IIO_CHAN_INFO_PROCESSED),
 199           .address              = MAX9611_CHAN_CURRENT_LOAD,
 200         },
 201         {
 202           .type                 = IIO_POWER,
 203           .info_mask_separate   = BIT(IIO_CHAN_INFO_PROCESSED),
 204           .address              = MAX9611_CHAN_POWER_LOAD
 205         },
 206 };
 207 
 208 /**
 209  * max9611_read_single() - read a single value from ADC interface
 210  *
 211  * Data registers are 16 bit long, spread between two 8 bit registers
 212  * with consecutive addresses.
 213  * Configure ADC mux first, then read register at address "reg_addr".
 214  * The smbus_read_word routine asks for 16 bits and the ADC is kind enough
 215  * to return values from "reg_addr" and "reg_addr + 1" consecutively.
 216  * Data are transmitted with big-endian ordering: MSB arrives first.
 217  *
 218  * @max9611: max9611 device
 219  * @selector: index for mux and register configuration
 220  * @raw_val: the value returned from ADC
 221  */
 222 static int max9611_read_single(struct max9611_dev *max9611,
 223                                enum max9611_conf_ids selector,
 224                                u16 *raw_val)
 225 {
 226         int ret;
 227 
 228         u8 mux_conf = max9611_mux_conf[selector][0] & MAX9611_MUX_MASK;
 229         u8 reg_addr = max9611_mux_conf[selector][1];
 230 
 231         /*
 232          * Keep mutex lock held during read-write to avoid mux register
 233          * (CTRL1) re-configuration.
 234          */
 235         mutex_lock(&max9611->lock);
 236         ret = i2c_smbus_write_byte_data(max9611->i2c_client,
 237                                         MAX9611_REG_CTRL1, mux_conf);
 238         if (ret) {
 239                 dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
 240                         MAX9611_REG_CTRL1, mux_conf);
 241                 mutex_unlock(&max9611->lock);
 242                 return ret;
 243         }
 244 
 245         /* need a delay here to make register configuration stabilize. */
 246 
 247         usleep_range(MAX9611_CONV_TIME_US_RANGE);
 248 
 249         ret = i2c_smbus_read_word_swapped(max9611->i2c_client, reg_addr);
 250         if (ret < 0) {
 251                 dev_err(max9611->dev, "i2c read word from 0x%2x failed\n",
 252                         reg_addr);
 253                 mutex_unlock(&max9611->lock);
 254                 return ret;
 255         }
 256 
 257         *raw_val = ret;
 258         mutex_unlock(&max9611->lock);
 259 
 260         return 0;
 261 }
 262 
 263 /**
 264  * max9611_read_csa_voltage() - read current sense amplifier output voltage
 265  *
 266  * Current sense amplifier output voltage is read through a configurable
 267  * 1x, 4x or 8x gain.
 268  * Start with plain 1x gain, and adjust gain control properly until a
 269  * meaningful value is read from ADC output.
 270  *
 271  * @max9611: max9611 device
 272  * @adc_raw: raw value read from ADC output
 273  * @csa_gain: gain configuration option selector
 274  */
 275 static int max9611_read_csa_voltage(struct max9611_dev *max9611,
 276                                     u16 *adc_raw,
 277                                     enum max9611_csa_gain *csa_gain)
 278 {
 279         enum max9611_conf_ids gain_selectors[] = {
 280                 CONF_SENSE_1x,
 281                 CONF_SENSE_4x,
 282                 CONF_SENSE_8x
 283         };
 284         unsigned int i;
 285         int ret;
 286 
 287         for (i = 0; i < ARRAY_SIZE(gain_selectors); ++i) {
 288                 ret = max9611_read_single(max9611, gain_selectors[i], adc_raw);
 289                 if (ret)
 290                         return ret;
 291 
 292                 if (*adc_raw > 0) {
 293                         *csa_gain = (enum max9611_csa_gain)gain_selectors[i];
 294                         return 0;
 295                 }
 296         }
 297 
 298         return -EIO;
 299 }
 300 
 301 static int max9611_read_raw(struct iio_dev *indio_dev,
 302                             struct iio_chan_spec const *chan,
 303                             int *val, int *val2, long mask)
 304 {
 305         struct max9611_dev *dev = iio_priv(indio_dev);
 306         enum max9611_csa_gain gain_selector;
 307         const unsigned int *csa_gain;
 308         u16 adc_data;
 309         int ret;
 310 
 311         switch (mask) {
 312         case IIO_CHAN_INFO_RAW:
 313 
 314                 switch (chan->address) {
 315                 case MAX9611_CHAN_TEMPERATURE:
 316                         ret = max9611_read_single(dev, CONF_TEMP,
 317                                                   &adc_data);
 318                         if (ret)
 319                                 return -EINVAL;
 320 
 321                         *val = MAX9611_TEMP_RAW(adc_data);
 322                         return IIO_VAL_INT;
 323 
 324                 case MAX9611_CHAN_VOLTAGE_INPUT:
 325                         ret = max9611_read_single(dev, CONF_IN_VOLT,
 326                                                   &adc_data);
 327                         if (ret)
 328                                 return -EINVAL;
 329 
 330                         *val = MAX9611_VOLTAGE_RAW(adc_data);
 331                         return IIO_VAL_INT;
 332                 }
 333 
 334                 break;
 335 
 336         case IIO_CHAN_INFO_OFFSET:
 337                 /* MAX9611_CHAN_VOLTAGE_INPUT */
 338                 *val = MAX9611_CIM_OFFSET_RAW;
 339 
 340                 return IIO_VAL_INT;
 341 
 342         case IIO_CHAN_INFO_SCALE:
 343 
 344                 switch (chan->address) {
 345                 case MAX9611_CHAN_TEMPERATURE:
 346                         *val = MAX9611_TEMP_SCALE_NUM;
 347                         *val2 = MAX9611_TEMP_SCALE_DIV;
 348 
 349                         return IIO_VAL_FRACTIONAL;
 350 
 351                 case MAX9611_CHAN_VOLTAGE_INPUT:
 352                         *val = MAX9611_CIM_LSB_mV;
 353 
 354                         return IIO_VAL_INT;
 355                 }
 356 
 357                 break;
 358 
 359         case IIO_CHAN_INFO_PROCESSED:
 360 
 361                 switch (chan->address) {
 362                 case MAX9611_CHAN_VOLTAGE_SENSE:
 363                         /*
 364                          * processed (mV): (raw - offset) * LSB (nV) / 10^6
 365                          *
 366                          * Even if max9611 can output raw csa voltage readings,
 367                          * use a produced value as scale depends on gain.
 368                          */
 369                         ret = max9611_read_csa_voltage(dev, &adc_data,
 370                                                        &gain_selector);
 371                         if (ret)
 372                                 return -EINVAL;
 373 
 374                         csa_gain = max9611_gain_conf[gain_selector];
 375 
 376                         adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
 377                         *val = MAX9611_VOLTAGE_RAW(adc_data) *
 378                                csa_gain[CSA_GAIN_LSB_nV];
 379                         *val2 = 1000000;
 380 
 381                         return IIO_VAL_FRACTIONAL;
 382 
 383                 case MAX9611_CHAN_CURRENT_LOAD:
 384                         /* processed (mA): Vcsa (nV) / Rshunt (uOhm)  */
 385                         ret = max9611_read_csa_voltage(dev, &adc_data,
 386                                                        &gain_selector);
 387                         if (ret)
 388                                 return -EINVAL;
 389 
 390                         csa_gain = max9611_gain_conf[gain_selector];
 391 
 392                         adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
 393                         *val = MAX9611_VOLTAGE_RAW(adc_data) *
 394                                csa_gain[CSA_GAIN_LSB_nV];
 395                         *val2 = dev->shunt_resistor_uohm;
 396 
 397                         return IIO_VAL_FRACTIONAL;
 398 
 399                 case MAX9611_CHAN_POWER_LOAD:
 400                         /*
 401                          * processed (mW): Vin (mV) * Vcsa (uV) /
 402                          *                 Rshunt (uOhm)
 403                          */
 404                         ret = max9611_read_single(dev, CONF_IN_VOLT,
 405                                                   &adc_data);
 406                         if (ret)
 407                                 return -EINVAL;
 408 
 409                         adc_data -= MAX9611_CIM_OFFSET_RAW;
 410                         *val = MAX9611_VOLTAGE_RAW(adc_data) *
 411                                MAX9611_CIM_LSB_mV;
 412 
 413                         ret = max9611_read_csa_voltage(dev, &adc_data,
 414                                                        &gain_selector);
 415                         if (ret)
 416                                 return -EINVAL;
 417 
 418                         csa_gain = max9611_gain_conf[gain_selector];
 419 
 420                         /* divide by 10^3 here to avoid 32bit overflow */
 421                         adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
 422                         *val *= MAX9611_VOLTAGE_RAW(adc_data) *
 423                                 csa_gain[CSA_GAIN_LSB_nV] / 1000;
 424                         *val2 = dev->shunt_resistor_uohm;
 425 
 426                         return IIO_VAL_FRACTIONAL;
 427                 }
 428 
 429                 break;
 430         }
 431 
 432         return -EINVAL;
 433 }
 434 
 435 static ssize_t max9611_shunt_resistor_show(struct device *dev,
 436                                            struct device_attribute *attr,
 437                                            char *buf)
 438 {
 439         struct max9611_dev *max9611 = iio_priv(dev_to_iio_dev(dev));
 440         unsigned int i, r;
 441 
 442         i = max9611->shunt_resistor_uohm / 1000000;
 443         r = max9611->shunt_resistor_uohm % 1000000;
 444 
 445         return sprintf(buf, "%u.%06u\n", i, r);
 446 }
 447 
 448 static IIO_DEVICE_ATTR(in_power_shunt_resistor, 0444,
 449                        max9611_shunt_resistor_show, NULL, 0);
 450 static IIO_DEVICE_ATTR(in_current_shunt_resistor, 0444,
 451                        max9611_shunt_resistor_show, NULL, 0);
 452 
 453 static struct attribute *max9611_attributes[] = {
 454         &iio_dev_attr_in_power_shunt_resistor.dev_attr.attr,
 455         &iio_dev_attr_in_current_shunt_resistor.dev_attr.attr,
 456         NULL,
 457 };
 458 
 459 static const struct attribute_group max9611_attribute_group = {
 460         .attrs = max9611_attributes,
 461 };
 462 
 463 static const struct iio_info indio_info = {
 464         .read_raw       = max9611_read_raw,
 465         .attrs          = &max9611_attribute_group,
 466 };
 467 
 468 static int max9611_init(struct max9611_dev *max9611)
 469 {
 470         struct i2c_client *client = max9611->i2c_client;
 471         u16 regval;
 472         int ret;
 473 
 474         if (!i2c_check_functionality(client->adapter,
 475                                      I2C_FUNC_SMBUS_WRITE_BYTE  |
 476                                      I2C_FUNC_SMBUS_READ_WORD_DATA)) {
 477                 dev_err(max9611->dev,
 478                         "I2c adapter does not support smbus write_byte or read_word functionalities: aborting probe.\n");
 479                 return -EINVAL;
 480         }
 481 
 482         /* Make sure die temperature is in range to test communications. */
 483         ret = max9611_read_single(max9611, CONF_TEMP, &regval);
 484         if (ret)
 485                 return ret;
 486 
 487         regval &= MAX9611_TEMP_MASK;
 488 
 489         if ((regval > MAX9611_TEMP_MAX_POS &&
 490              regval < MAX9611_TEMP_MIN_NEG) ||
 491              regval > MAX9611_TEMP_MAX_NEG) {
 492                 dev_err(max9611->dev,
 493                         "Invalid value received from ADC 0x%4x: aborting\n",
 494                         regval);
 495                 return -EIO;
 496         }
 497 
 498         /* Mux shall be zeroed back before applying other configurations */
 499         ret = i2c_smbus_write_byte_data(max9611->i2c_client,
 500                                         MAX9611_REG_CTRL1, 0);
 501         if (ret) {
 502                 dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
 503                         MAX9611_REG_CTRL1, 0);
 504                 return ret;
 505         }
 506 
 507         ret = i2c_smbus_write_byte_data(max9611->i2c_client,
 508                                         MAX9611_REG_CTRL2, 0);
 509         if (ret) {
 510                 dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
 511                         MAX9611_REG_CTRL2, 0);
 512                 return ret;
 513         }
 514         usleep_range(MAX9611_CONV_TIME_US_RANGE);
 515 
 516         return 0;
 517 }
 518 
 519 static const struct of_device_id max9611_of_table[] = {
 520         {.compatible = "maxim,max9611", .data = "max9611"},
 521         {.compatible = "maxim,max9612", .data = "max9612"},
 522         { },
 523 };
 524 
 525 MODULE_DEVICE_TABLE(of, max9611_of_table);
 526 static int max9611_probe(struct i2c_client *client,
 527                          const struct i2c_device_id *id)
 528 {
 529         const char * const shunt_res_prop = "shunt-resistor-micro-ohms";
 530         const struct device_node *of_node = client->dev.of_node;
 531         const struct of_device_id *of_id =
 532                 of_match_device(max9611_of_table, &client->dev);
 533         struct max9611_dev *max9611;
 534         struct iio_dev *indio_dev;
 535         unsigned int of_shunt;
 536         int ret;
 537 
 538         indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max9611));
 539         if (!indio_dev)
 540                 return -ENOMEM;
 541 
 542         i2c_set_clientdata(client, indio_dev);
 543 
 544         max9611                 = iio_priv(indio_dev);
 545         max9611->dev            = &client->dev;
 546         max9611->i2c_client     = client;
 547         mutex_init(&max9611->lock);
 548 
 549         ret = of_property_read_u32(of_node, shunt_res_prop, &of_shunt);
 550         if (ret) {
 551                 dev_err(&client->dev,
 552                         "Missing %s property for %pOF node\n",
 553                         shunt_res_prop, of_node);
 554                 return ret;
 555         }
 556         max9611->shunt_resistor_uohm = of_shunt;
 557 
 558         ret = max9611_init(max9611);
 559         if (ret)
 560                 return ret;
 561 
 562         indio_dev->dev.parent   = &client->dev;
 563         indio_dev->dev.of_node  = client->dev.of_node;
 564         indio_dev->name         = of_id->data;
 565         indio_dev->modes        = INDIO_DIRECT_MODE;
 566         indio_dev->info         = &indio_info;
 567         indio_dev->channels     = max9611_channels;
 568         indio_dev->num_channels = ARRAY_SIZE(max9611_channels);
 569 
 570         return devm_iio_device_register(&client->dev, indio_dev);
 571 }
 572 
 573 static struct i2c_driver max9611_driver = {
 574         .driver = {
 575                    .name = DRIVER_NAME,
 576                    .of_match_table = max9611_of_table,
 577         },
 578         .probe = max9611_probe,
 579 };
 580 module_i2c_driver(max9611_driver);
 581 
 582 MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
 583 MODULE_DESCRIPTION("Maxim max9611/12 current sense amplifier with 12bit ADC");
 584 MODULE_LICENSE("GPL v2");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/iio/adc/max9611.c

DEFINITIONS
