drivers/hwmon/ltc4245.c

   1 /*
   2  * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
   3  *
   4  * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * This driver is based on the ds1621 and ina209 drivers.
  11  *
  12  * Datasheet:
  13  * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19 #include <linux/err.h>
  20 #include <linux/slab.h>
  21 #include <linux/i2c.h>
  22 #include <linux/hwmon.h>
  23 #include <linux/hwmon-sysfs.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/i2c/ltc4245.h>
  26
  27 /* Here are names of the chip's registers (a.k.a. commands) */
  28 enum ltc4245_cmd {
  29         LTC4245_STATUS                  = 0x00, /* readonly */
  30         LTC4245_ALERT                   = 0x01,
  31         LTC4245_CONTROL                 = 0x02,
  32         LTC4245_ON                      = 0x03,
  33         LTC4245_FAULT1                  = 0x04,
  34         LTC4245_FAULT2                  = 0x05,
  35         LTC4245_GPIO                    = 0x06,
  36         LTC4245_ADCADR                  = 0x07,
  37
  38         LTC4245_12VIN                   = 0x10,
  39         LTC4245_12VSENSE                = 0x11,
  40         LTC4245_12VOUT                  = 0x12,
  41         LTC4245_5VIN                    = 0x13,
  42         LTC4245_5VSENSE                 = 0x14,
  43         LTC4245_5VOUT                   = 0x15,
  44         LTC4245_3VIN                    = 0x16,
  45         LTC4245_3VSENSE                 = 0x17,
  46         LTC4245_3VOUT                   = 0x18,
  47         LTC4245_VEEIN                   = 0x19,
  48         LTC4245_VEESENSE                = 0x1a,
  49         LTC4245_VEEOUT                  = 0x1b,
  50         LTC4245_GPIOADC                 = 0x1c,
  51 };
  52
  53 struct ltc4245_data {
  54         struct i2c_client *client;
  55
  56         const struct attribute_group *groups[3];
  57
  58         struct mutex update_lock;
  59         bool valid;
  60         unsigned long last_updated; /* in jiffies */
  61
  62         /* Control registers */
  63         u8 cregs[0x08];
  64
  65         /* Voltage registers */
  66         u8 vregs[0x0d];
  67
  68         /* GPIO ADC registers */
  69         bool use_extra_gpios;
  70         int gpios[3];
  71 };
  72
  73 /*
  74  * Update the readings from the GPIO pins. If the driver has been configured to
  75  * sample all GPIO's as analog voltages, a round-robin sampling method is used.
  76  * Otherwise, only the configured GPIO pin is sampled.
  77  *
  78  * LOCKING: must hold data->update_lock
  79  */
  80 static void ltc4245_update_gpios(struct device *dev)
  81 {
  82         struct ltc4245_data *data = dev_get_drvdata(dev);
  83         struct i2c_client *client = data->client;
  84         u8 gpio_curr, gpio_next, gpio_reg;
  85         int i;
  86
  87         /* no extra gpio support, we're basically done */
  88         if (!data->use_extra_gpios) {
  89                 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
  90                 return;
  91         }
  92
  93         /*
  94          * If the last reading was too long ago, then we mark all old GPIO
  95          * readings as stale by setting them to -EAGAIN
  96          */
  97         if (time_after(jiffies, data->last_updated + 5 * HZ)) {
  98                 for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
  99                         data->gpios[i] = -EAGAIN;
 100         }
 101
 102         /*
 103          * Get the current GPIO pin
 104          *
 105          * The datasheet calls these GPIO[1-3], but we'll calculate the zero
 106          * based array index instead, and call them GPIO[0-2]. This is much
 107          * easier to think about.
 108          */
 109         gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
 110         if (gpio_curr > 0)
 111                 gpio_curr -= 1;
 112
 113         /* Read the GPIO voltage from the GPIOADC register */
 114         data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
 115
 116         /* Find the next GPIO pin to read */
 117         gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
 118
 119         /*
 120          * Calculate the correct setting for the GPIO register so it will
 121          * sample the next GPIO pin
 122          */
 123         gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
 124
 125         /* Update the GPIO register */
 126         i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
 127
 128         /* Update saved data */
 129         data->cregs[LTC4245_GPIO] = gpio_reg;
 130 }
 131
 132 static struct ltc4245_data *ltc4245_update_device(struct device *dev)
 133 {
 134         struct ltc4245_data *data = dev_get_drvdata(dev);
 135         struct i2c_client *client = data->client;
 136         s32 val;
 137         int i;
 138
 139         mutex_lock(&data->update_lock);
 140
 141         if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 142
 143                 /* Read control registers -- 0x00 to 0x07 */
 144                 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
 145                         val = i2c_smbus_read_byte_data(client, i);
 146                         if (unlikely(val < 0))
 147                                 data->cregs[i] = 0;
 148                         else
 149                                 data->cregs[i] = val;
 150                 }
 151
 152                 /* Read voltage registers -- 0x10 to 0x1c */
 153                 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
 154                         val = i2c_smbus_read_byte_data(client, i+0x10);
 155                         if (unlikely(val < 0))
 156                                 data->vregs[i] = 0;
 157                         else
 158                                 data->vregs[i] = val;
 159                 }
 160
 161                 /* Update GPIO readings */
 162                 ltc4245_update_gpios(dev);
 163
 164                 data->last_updated = jiffies;
 165                 data->valid = 1;
 166         }
 167
 168         mutex_unlock(&data->update_lock);
 169
 170         return data;
 171 }
 172
 173 /* Return the voltage from the given register in millivolts */
 174 static int ltc4245_get_voltage(struct device *dev, u8 reg)
 175 {
 176         struct ltc4245_data *data = ltc4245_update_device(dev);
 177         const u8 regval = data->vregs[reg - 0x10];
 178         u32 voltage = 0;
 179
 180         switch (reg) {
 181         case LTC4245_12VIN:
 182         case LTC4245_12VOUT:
 183                 voltage = regval * 55;
 184                 break;
 185         case LTC4245_5VIN:
 186         case LTC4245_5VOUT:
 187                 voltage = regval * 22;
 188                 break;
 189         case LTC4245_3VIN:
 190         case LTC4245_3VOUT:
 191                 voltage = regval * 15;
 192                 break;
 193         case LTC4245_VEEIN:
 194         case LTC4245_VEEOUT:
 195                 voltage = regval * -55;
 196                 break;
 197         case LTC4245_GPIOADC:
 198                 voltage = regval * 10;
 199                 break;
 200         default:
 201                 /* If we get here, the developer messed up */
 202                 WARN_ON_ONCE(1);
 203                 break;
 204         }
 205
 206         return voltage;
 207 }
 208
 209 /* Return the current in the given sense register in milliAmperes */
 210 static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
 211 {
 212         struct ltc4245_data *data = ltc4245_update_device(dev);
 213         const u8 regval = data->vregs[reg - 0x10];
 214         unsigned int voltage;
 215         unsigned int curr;
 216
 217         /*
 218          * The strange looking conversions that follow are fixed-point
 219          * math, since we cannot do floating point in the kernel.
 220          *
 221          * Step 1: convert sense register to microVolts
 222          * Step 2: convert voltage to milliAmperes
 223          *
 224          * If you play around with the V=IR equation, you come up with
 225          * the following: X uV / Y mOhm == Z mA
 226          *
 227          * With the resistors that are fractions of a milliOhm, we multiply
 228          * the voltage and resistance by 10, to shift the decimal point.
 229          * Now we can use the normal division operator again.
 230          */
 231
 232         switch (reg) {
 233         case LTC4245_12VSENSE:
 234                 voltage = regval * 250; /* voltage in uV */
 235                 curr = voltage / 50; /* sense resistor 50 mOhm */
 236                 break;
 237         case LTC4245_5VSENSE:
 238                 voltage = regval * 125; /* voltage in uV */
 239                 curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
 240                 break;
 241         case LTC4245_3VSENSE:
 242                 voltage = regval * 125; /* voltage in uV */
 243                 curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
 244                 break;
 245         case LTC4245_VEESENSE:
 246                 voltage = regval * 250; /* voltage in uV */
 247                 curr = voltage / 100; /* sense resistor 100 mOhm */
 248                 break;
 249         default:
 250                 /* If we get here, the developer messed up */
 251                 WARN_ON_ONCE(1);
 252                 curr = 0;
 253                 break;
 254         }
 255
 256         return curr;
 257 }
 258
 259 static ssize_t ltc4245_show_voltage(struct device *dev,
 260                                     struct device_attribute *da,
 261                                     char *buf)
 262 {
 263         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 264         const int voltage = ltc4245_get_voltage(dev, attr->index);
 265
 266         return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
 267 }
 268
 269 static ssize_t ltc4245_show_current(struct device *dev,
 270                                     struct device_attribute *da,
 271                                     char *buf)
 272 {
 273         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 274         const unsigned int curr = ltc4245_get_current(dev, attr->index);
 275
 276         return snprintf(buf, PAGE_SIZE, "%u\n", curr);
 277 }
 278
 279 static ssize_t ltc4245_show_power(struct device *dev,
 280                                   struct device_attribute *da,
 281                                   char *buf)
 282 {
 283         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 284         const unsigned int curr = ltc4245_get_current(dev, attr->index);
 285         const int output_voltage = ltc4245_get_voltage(dev, attr->index+1);
 286
 287         /* current in mA * voltage in mV == power in uW */
 288         const unsigned int power = abs(output_voltage * curr);
 289
 290         return snprintf(buf, PAGE_SIZE, "%u\n", power);
 291 }
 292
 293 static ssize_t ltc4245_show_alarm(struct device *dev,
 294                                           struct device_attribute *da,
 295                                           char *buf)
 296 {
 297         struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
 298         struct ltc4245_data *data = ltc4245_update_device(dev);
 299         const u8 reg = data->cregs[attr->index];
 300         const u32 mask = attr->nr;
 301
 302         return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
 303 }
 304
 305 static ssize_t ltc4245_show_gpio(struct device *dev,
 306                                  struct device_attribute *da,
 307                                  char *buf)
 308 {
 309         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 310         struct ltc4245_data *data = ltc4245_update_device(dev);
 311         int val = data->gpios[attr->index];
 312
 313         /* handle stale GPIO's */
 314         if (val < 0)
 315                 return val;
 316
 317         /* Convert to millivolts and print */
 318         return snprintf(buf, PAGE_SIZE, "%u\n", val * 10);
 319 }
 320
 321 /* Construct a sensor_device_attribute structure for each register */
 322
 323 /* Input voltages */
 324 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4245_show_voltage, NULL,
 325                           LTC4245_12VIN);
 326 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4245_show_voltage, NULL,
 327                           LTC4245_5VIN);
 328 static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ltc4245_show_voltage, NULL,
 329                           LTC4245_3VIN);
 330 static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ltc4245_show_voltage, NULL,
 331                           LTC4245_VEEIN);
 332
 333 /* Input undervoltage alarms */
 334 static SENSOR_DEVICE_ATTR_2(in1_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 335                             1 << 0, LTC4245_FAULT1);
 336 static SENSOR_DEVICE_ATTR_2(in2_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 337                             1 << 1, LTC4245_FAULT1);
 338 static SENSOR_DEVICE_ATTR_2(in3_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 339                             1 << 2, LTC4245_FAULT1);
 340 static SENSOR_DEVICE_ATTR_2(in4_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 341                             1 << 3, LTC4245_FAULT1);
 342
 343 /* Currents (via sense resistor) */
 344 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4245_show_current, NULL,
 345                           LTC4245_12VSENSE);
 346 static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc4245_show_current, NULL,
 347                           LTC4245_5VSENSE);
 348 static SENSOR_DEVICE_ATTR(curr3_input, S_IRUGO, ltc4245_show_current, NULL,
 349                           LTC4245_3VSENSE);
 350 static SENSOR_DEVICE_ATTR(curr4_input, S_IRUGO, ltc4245_show_current, NULL,
 351                           LTC4245_VEESENSE);
 352
 353 /* Overcurrent alarms */
 354 static SENSOR_DEVICE_ATTR_2(curr1_max_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 355                             1 << 4, LTC4245_FAULT1);
 356 static SENSOR_DEVICE_ATTR_2(curr2_max_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 357                             1 << 5, LTC4245_FAULT1);
 358 static SENSOR_DEVICE_ATTR_2(curr3_max_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 359                             1 << 6, LTC4245_FAULT1);
 360 static SENSOR_DEVICE_ATTR_2(curr4_max_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 361                             1 << 7, LTC4245_FAULT1);
 362
 363 /* Output voltages */
 364 static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ltc4245_show_voltage, NULL,
 365                           LTC4245_12VOUT);
 366 static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ltc4245_show_voltage, NULL,
 367                           LTC4245_5VOUT);
 368 static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ltc4245_show_voltage, NULL,
 369                           LTC4245_3VOUT);
 370 static SENSOR_DEVICE_ATTR(in8_input, S_IRUGO, ltc4245_show_voltage, NULL,
 371                           LTC4245_VEEOUT);
 372
 373 /* Power Bad alarms */
 374 static SENSOR_DEVICE_ATTR_2(in5_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 375                             1 << 0, LTC4245_FAULT2);
 376 static SENSOR_DEVICE_ATTR_2(in6_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 377                             1 << 1, LTC4245_FAULT2);
 378 static SENSOR_DEVICE_ATTR_2(in7_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 379                             1 << 2, LTC4245_FAULT2);
 380 static SENSOR_DEVICE_ATTR_2(in8_min_alarm, S_IRUGO, ltc4245_show_alarm, NULL,
 381                             1 << 3, LTC4245_FAULT2);
 382
 383 /* GPIO voltages */
 384 static SENSOR_DEVICE_ATTR(in9_input, S_IRUGO, ltc4245_show_gpio, NULL, 0);
 385 static SENSOR_DEVICE_ATTR(in10_input, S_IRUGO, ltc4245_show_gpio, NULL, 1);
 386 static SENSOR_DEVICE_ATTR(in11_input, S_IRUGO, ltc4245_show_gpio, NULL, 2);
 387
 388 /* Power Consumption (virtual) */
 389 static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc4245_show_power, NULL,
 390                           LTC4245_12VSENSE);
 391 static SENSOR_DEVICE_ATTR(power2_input, S_IRUGO, ltc4245_show_power, NULL,
 392                           LTC4245_5VSENSE);
 393 static SENSOR_DEVICE_ATTR(power3_input, S_IRUGO, ltc4245_show_power, NULL,
 394                           LTC4245_3VSENSE);
 395 static SENSOR_DEVICE_ATTR(power4_input, S_IRUGO, ltc4245_show_power, NULL,
 396                           LTC4245_VEESENSE);
 397
 398 /*
 399  * Finally, construct an array of pointers to members of the above objects,
 400  * as required for sysfs_create_group()
 401  */
 402 static struct attribute *ltc4245_std_attributes[] = {
 403         &sensor_dev_attr_in1_input.dev_attr.attr,
 404         &sensor_dev_attr_in2_input.dev_attr.attr,
 405         &sensor_dev_attr_in3_input.dev_attr.attr,
 406         &sensor_dev_attr_in4_input.dev_attr.attr,
 407
 408         &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 409         &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 410         &sensor_dev_attr_in3_min_alarm.dev_attr.attr,
 411         &sensor_dev_attr_in4_min_alarm.dev_attr.attr,
 412
 413         &sensor_dev_attr_curr1_input.dev_attr.attr,
 414         &sensor_dev_attr_curr2_input.dev_attr.attr,
 415         &sensor_dev_attr_curr3_input.dev_attr.attr,
 416         &sensor_dev_attr_curr4_input.dev_attr.attr,
 417
 418         &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
 419         &sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
 420         &sensor_dev_attr_curr3_max_alarm.dev_attr.attr,
 421         &sensor_dev_attr_curr4_max_alarm.dev_attr.attr,
 422
 423         &sensor_dev_attr_in5_input.dev_attr.attr,
 424         &sensor_dev_attr_in6_input.dev_attr.attr,
 425         &sensor_dev_attr_in7_input.dev_attr.attr,
 426         &sensor_dev_attr_in8_input.dev_attr.attr,
 427
 428         &sensor_dev_attr_in5_min_alarm.dev_attr.attr,
 429         &sensor_dev_attr_in6_min_alarm.dev_attr.attr,
 430         &sensor_dev_attr_in7_min_alarm.dev_attr.attr,
 431         &sensor_dev_attr_in8_min_alarm.dev_attr.attr,
 432
 433         &sensor_dev_attr_in9_input.dev_attr.attr,
 434
 435         &sensor_dev_attr_power1_input.dev_attr.attr,
 436         &sensor_dev_attr_power2_input.dev_attr.attr,
 437         &sensor_dev_attr_power3_input.dev_attr.attr,
 438         &sensor_dev_attr_power4_input.dev_attr.attr,
 439
 440         NULL,
 441 };
 442
 443 static struct attribute *ltc4245_gpio_attributes[] = {
 444         &sensor_dev_attr_in10_input.dev_attr.attr,
 445         &sensor_dev_attr_in11_input.dev_attr.attr,
 446         NULL,
 447 };
 448
 449 static const struct attribute_group ltc4245_std_group = {
 450         .attrs = ltc4245_std_attributes,
 451 };
 452
 453 static const struct attribute_group ltc4245_gpio_group = {
 454         .attrs = ltc4245_gpio_attributes,
 455 };
 456
 457 static void ltc4245_sysfs_add_groups(struct ltc4245_data *data)
 458 {
 459         /* standard sysfs attributes */
 460         data->groups[0] = &ltc4245_std_group;
 461
 462         /* if we're using the extra gpio support, register it's attributes */
 463         if (data->use_extra_gpios)
 464                 data->groups[1] = &ltc4245_gpio_group;
 465 }
 466
 467 static bool ltc4245_use_extra_gpios(struct i2c_client *client)
 468 {
 469         struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
 470         struct device_node *np = client->dev.of_node;
 471
 472         /* prefer platform data */
 473         if (pdata)
 474                 return pdata->use_extra_gpios;
 475
 476         /* fallback on OF */
 477         if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
 478                 return true;
 479
 480         return false;
 481 }
 482
 483 static int ltc4245_probe(struct i2c_client *client,
 484                          const struct i2c_device_id *id)
 485 {
 486         struct i2c_adapter *adapter = client->adapter;
 487         struct ltc4245_data *data;
 488         struct device *hwmon_dev;
 489
 490         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 491                 return -ENODEV;
 492
 493         data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 494         if (!data)
 495                 return -ENOMEM;
 496
 497         data->client = client;
 498         mutex_init(&data->update_lock);
 499         data->use_extra_gpios = ltc4245_use_extra_gpios(client);
 500
 501         /* Initialize the LTC4245 chip */
 502         i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
 503         i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
 504
 505         /* Add sysfs hooks */
 506         ltc4245_sysfs_add_groups(data);
 507
 508         hwmon_dev = devm_hwmon_device_register_with_groups(&client->dev,
 509                                                            client->name, data,
 510                                                            data->groups);
 511         return PTR_ERR_OR_ZERO(hwmon_dev);
 512 }
 513
 514 static const struct i2c_device_id ltc4245_id[] = {
 515         { "ltc4245", 0 },
 516         { }
 517 };
 518 MODULE_DEVICE_TABLE(i2c, ltc4245_id);
 519
 520 /* This is the driver that will be inserted */
 521 static struct i2c_driver ltc4245_driver = {
 522         .driver = {
 523                 .name   = "ltc4245",
 524         },
 525         .probe          = ltc4245_probe,
 526         .id_table       = ltc4245_id,
 527 };
 528
 529 module_i2c_driver(ltc4245_driver);
 530
 531 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 532 MODULE_DESCRIPTION("LTC4245 driver");
 533 MODULE_LICENSE("GPL");